Channeling 2016

25 Sept 2016, 00:00 → 30 Sept 2016, 18:05 Europe/Rome

FRANK ZIMMERMANN (CERN), Luigi Palumbo (ROMA1), Sultan Dabagov (LNF)

The 7^th International Conference "Charged & Neutral Particles Channeling Phenomena Channeling 2016" organized by the Italian National Institute for Nuclear Physics (INFN) and the European Organization for Nuclear Research (CERN) will be held in SIRMIONE-DESENZANO DEL GARDA (Italy) on September 25-30, 2016.

Slides ch2016-advance_program.pdf

Sunday, 25 September

Registration

Channeling Primer

Convener: Sultan Dabagov (LNF)

1 Opening

Speakers: FRANK ZIMMERMANN (CERN), Luigi Palumbo (ROMA1), Sultan Dabagov (LNF)

2 Greetings by Comune di Sirmione Del Garda

3 Greetings by President of INFN

President of INFN Prof. Fernando Ferroni will greet the participants of Channeling 2016

Speaker: Prof. Fernando Ferroni (ROMA1)

Slides ferroni_ch2016.pdf

4 ... From LHC to FCC ...

Lessons learned from LHC allow the definition of new strategies for future collider concepts

Speaker: FRANK ZIMMERMANN (CERN)

Slides zimmermann_Ch2016.pdf

5 Undulator and Free Electron Laser radiation for Fundamental Physics research

Free Electron Lasers are widely exploited in applications and are now very effective tools for different types of studies from Solid State Physics to Structural Biology. The reliability of these devices, the high spectral flux, the possibility of controlling the spectral purity and the time duration of the individual pulses makes them attractive in further fields of research, including fundamental problems regarding fundamental test in quantum electrodynamics and the search for dark matter as well. In this talk, we review some of these possibilities and discuss how FEL oscillators may provide the elements for integrated facilities allowing applied and fundamental research within the context of medium size laboratories.

Speaker: Giuseppe Dattoli (ENEA-Frascati)

Slides dattoli_ch2016.pdf

6 Channeling for Beams & Radiations. 50..40..30 Years History

Practically 50 years past since the phenomenology for charged particles channeling in crystals has been proposed by Lindhard. This pioneering work that provides correct description of charged particles motion in oriented crystals at small beam incident angle with respect to main crystallographic directions, resulting in either planar or axial channeling, was followed by many research papers, reviews and books with a number of brilliant ideas that became well known and even wide used in the world. Two of these ideas have been finalized in very attractive research branches till now capable proposing new collaborations and projects. One of them is known as a channeling radiation phenomenon, which was predicted quasi 40 years ago by Kumakhov, recognized as one of the most powerful electromagnetic radiation sources of gamma- and x-ray frequencies by light relativistic charged particles, to be called “crystal undulator”. Another strictly related subject of intense research started his history ~ 30 years ago from the construction of the first polycapillary lens at the Laboratory for electromagnetic interactions of the Kurchatov Institute. This technology, known as polycapillary optics, is based on channeling of neutral particles in hollow tubes, especially, on x-ray and neutron channeling in capillaries. This report will recollect most important discoveries, events and key steps of channeling physics done within various international collaborations.

Speakers: Prof. Joseph REMILLIEUX (Institut de Physique Nucléaire de Lyon), Prof. Sultan Dabagov (LNF)

Slides remillieux-dabagov_ch2016.pdf

7 NRNU “MEPhI”: from University Basics to Advanced Technologies

MEPhI was founded during World War II in 23 November, 1942 initially as Moscow Mechanical Institute of Ammunition by I.Stalin’s personal order. The main goal of its foundation was to collect brilliant minds together, train them and urgently start research in creation of nuclear weapon. Since the end of 50-th the main goal of Moscow Engineering Physics Institute is the people ware for developing of nuclear industry (research, engineering, technologies). National Research Nuclear University MEPhI was created as an educational and research holding for nuclear industry inside and outside of the Russian Federation. MEPhI is the Russian Nuclear Education Center. NRNU MEPhI has more than 40 educational programs and more than 30 directions of postgraduate education. NRNU MEPhI is nuclear, bio- and nanotechnologies university. The former structure is departments (Faculties): Department (faculty) of experimental and theoretical physics; Department (faculty) of physics and nuclear power systems; Department (faculty) of automatics and electronics; Department (faculty) of cybernetics and information security; Department (faculty) of management and economics of high technologies. The modern structure is institutes (SAU - Strategical Academic Units) (The main goal of the transformation faculty divisions into institutes is combined the basic departments on the base of one or more centers of excellence and the multidisciplinary approach): Institute of high energy physics; Institute of nuclear physics and technologies; Institute of nanotechnologies; Institute of nuclear medicine; Institute of cybernetics and information security; Institute of management and economics of high technologies; Institute of fundamental natural sciences. Modern NRNU MEPhI is Research & Educational Centers & Laboratories. (Nuclear reactor center, Radiation material science and radiation protection center, Physical protection, control and accounting of nuclear materials center, Radiation accelerator center, Neutrino Lab, Nuclear electronics center, Carbon fiber and carbon-composite material center, Superconductivity center, Nanosystems, nanomaterials and nanotechnologies center, Laser technological center, etc.) NRNU MEPhI participates in a large number of the international (collaborations) experiments (STAR, ATLAS, ALICE, PAMELA, ARINA, CORONAS-PHOTON etc.) MEPhI set an ambitious goal to become a global leader in education, science and innovations

Speaker: Prof. Nikolay Kalashnikov (National Research Nuclear University Mephi)

Slides kalshnikov-mephi_ch2016.pdf

8 Greetings by MSTU /Maykop/

Maykop State Technological University (RF, Adygheya, Maykop)

Speaker: Prof. Saida Kuizheva (Rector of MSTU)

Welcome Party

Convener: Francesca Casarin Calenda (LNF)

Monday, 26 September

S1.1: Channeling & Radiations in Crystals

Convener: Sultan Dabagov (LNF)

9 The phenomena of spin rotation and depolarization of high-energy particles in crystals at Hadron Collider (LHC) and Future Circular Collider (FCC) energies and the possibility to measure the anomalous magnetic moments of short-lived particles (charm and beauty baryons) and quadrupole moment of $\Omega$-hyperon

The phenomena of spin rotation and depolarization of high-energy particles in crystals in the range of high energies that will be available at Future Circular Collider (FCC) can be used to measure the anomalous magnetic moments of short-lived particles. We demonstrate that the phenomenon of particle spin depolarization in crystals provides a unique possibility of measuring the anomalous magnetic moment of negatively-charged particles (e.g., beauty baryons), for which the channeling effect is hampered due to far more rapid dechanneling as compared to that for positively-charged particles. It is noteworthy that strong fluctuating fields act on neutral particles moving at a small angle to the crystal axes (planes), too, leading to the depolarization of their spin, which fact can be used to measure the magnetic moment of neutral particles. It is shown that the estimated number of produced baryons that are captured into a bent crystal or undergo effective depolarization in a straight crystal grows as ~ $\gamma^{3/2}$ with increasing particle energy. Hence it may be concluded that, for example, the experimental measurement of magnetic moments of short-lived particles using the spin rotation effect is feasible at LHC and higher energies (for 7 TeV the running time required for measuring the magnetic moment of $\Lambda^{+}_{c}$ is 2-16 hours).

Speaker: Prof. Vladimir Baryshevsky (Belarusian state University, Institute for Nuclear Problems)

Slides baryshevsky_ch2016-inv.pdf

10 Correlations in thermal vibrations of crystal atoms. Effect on bremsstrahlung and dechanneling

Thermal vibrations of neighboring atoms are correlated : long wavelength phonons make them displace in the same direction. For channeled particle the correlated displacements make dechanneling faster. For channeled electrons or positrons, it increases the coherence of bremsstrahlung over consecutive atoms, making a kind of semi-coherent contribution to bremsstrahlung . These effects are studied in the binary collision approach. The validity of this approach is discussed in the light of quantum scattering theory.

Speaker: Mr Xavier Artru (Université de Lyon, CNRS/IN2P3, IPNL)

Slides artru_ch2016-1.pdf

11 Quantitative theory of channeling particle diffusion in transverse energy and direct evaluation of dechanneling length

A new diffusion equation is suggested to correctly describe the channeling particle diffusion in transverse energy, taking into consideration the contribution of both the fourth power of incoherent scattering angle to the transverse energy dispersion and the catastrophic dechanneling effect, caused by the large-angle single incoherent scattering. This equation is reduced to the Sturm-Liouville problem applied both to rigorously introduce and evaluate numerically with a one-percent precision the dechanneling length as well as the percentage of the channeling positively charged particles for the SPS, LHC and FCC energies. On the opposite, an application of this newly formulated diffusion theory to the case of negatively charged particles confirms our previous conclusion, made on the basis of both the experimental studies and Monte Carlo simulations, that an application of the dechanneling length concept is possible for them only after the consideration of both intensive particle dechanneling and rechanneling processes.

Speaker: Prof. Victor Tikhomirov (Institute for Nuclear Problems)

Slides Tikhomirov.pdf

12 Superposition of waves in interference field and channeling radiation

Spectral features of proton channeling radiation, revealed by the interference of two modes of circular waves with the same frequency and amplitude, are studied. The beam modulation is resolved using the realistic Monte Carlo simulation by taking into account the degree of spatial coherence and longitudinal coherence length, multiple scattering effect, electron energy loss, emission angles, and polarization factors. The resulting interference patterns are strongly affected by the superposition of circular waves that are associated to distinct wave phases difference, produced at different points transverse and longitudinal to the direction of particle propagation in crystal channel. The spherical wavefronts are induced by atomic vibrations considering individual lattice atoms as one dimensional harmonic oscillators or point sources, trough binary collision process. Our investigation shows that more robust stability of coherence of the beam of perfectly superposed waves in interference field, as well as controlled channeling radiation, could enable probing of time resolved processes with unprecedented resolution, since significant improvements of stability and reproducibility may be utilized for adequate bunching and modulation for coherent emission, when the modulated density of energetic particles approaches the wavelength of the channeling radiation.

Speaker: Dr Vesna Berec (Institute of Nuclear Sciences Vinca, University of Belgrade)

13 Quantum and classical effects in scattering of fast electrons by the atomic planes of ultrathin crystal

At motion of accelerated charged particle through crystal the phenomenon of plane channeling is possible, at which the particle performs oscillatory motion in the channel formed by crystal planes. In ultrathin crystals such regime fails to be established, and a problem appears on the properties of motion and scattering of particles in this case. For MeV electrons such a transitional motion regime takes place in the crystals less that 0.1 micron thick. Since last years, there exist accelerator experiments with such crystals [1,2]. In the present work we present the results of study of the scattering process of relativistic electrons in this case. The classical and quantum theories of such process are developed. The quantum study is based upon so-called spectral method [3-5] of finding of the electron wave function in the crystal. It is shown that for MeV electrons the quantum effects are substantial, that manifest themselves as sharp maxima in the angular distributions of scattered particles, being characterized by the crystal inverse grating vectors. As the particle energy increases up to GeV range the possibility of multiple rainbow scattering within the transitional range of crystal thicknesses appears, that reveals itself in quantum so far as in classical consideration. With the energy increase the quantum effects in scattering smoothly turn into the classical ones. The influence of the beam divergence that strongly affects the scattering picture, particularly the quantum one, is studied. The possibility of experimental observation of the considered effects is studied [6]. References 1. V. Guidi, A. Mazzolari, et al., Physical Review Letters 108 (2012) 014801. 2. M. Motapothula, Z.Y. Dang, et al., NIM B283 (2012) 29-34. 3. M.D. Feit, J.A. Fleck, A. Steiger. J. of Comp. Phys. 47 (1982) 412. 4. S.B. Dabagov, L.I. Ognev. NIM B30 (1988) 185. 5. A.V. Kozlov, N.F. Shul’ga, V.A. Cherkaskiy. Phys. Lett. A374 (2010) 4690. 6. S.N. Shul'ga, N.F. Shul'ga, S. Barsuk, I. Chaikovska, R. Chehab. arXiv:1512.040601v1 (2015).

Speaker: Dr Sergiy Shulga (National Science Center "Kharkiv Institute of Physics and Technology")

Slides shulga_ch2016.pdf

14 First observation of scattering of sub-GeV electrons in ultrathin Si crystal at planar alignment and relevance to crystal-assisted rainbow scattering

This work presents continuation of experimental and theoretical studies of the scattering of 255 MeV electrons by aligned crystals at SAGA-LS accelerator facility. In the previous series of experiments we studied the doughnut scattering (DS) [1], scattering at planar alignment (SPA) [2] and mirroring [3-5]. The advantage of these studies is the fixed electron beam energy and different crystal thicknesses which allows distinguish these types of scattering. The goal of the present paper is experimental and theoretical search for another type of scattering named rainbow scattering (RS). The RS is very specific type of scattering which in general appears in the scattering of the waves and particles (both classical and quantum), see e.g [6-7]. The earlier works on appearance of RS at ions channeling are reviewed (axially channeled 7-MeV and 2-MeV protons) in [8]. The very precise studies of crystal-assisted RS in the case of non-relativistic ions were performed by N. Neškovi´c et al, since Ref. [9]. In the classical theory of crystal rainbows the key aspect is an unusual dependence of the deflection angle on the impact parameter with a crystal axis. The RS for high-energy electrons (100 and 500 MeV) at axial alignment was theoretically considered in Ref. [10] using both classical and quantum approaches and Lindhard’s string potential. The theory predicted some contradictions between classical and quantum approaches. Recently, similar contradictions between classical and quantum theories of RS in the case of planar alignment and 4 – 50 MeV electrons were discussed in [11] but again using non-realistic planar channeling potential. At the moment, there is a lack of the experimental data on high-energy electrons RS in a crystal. Our experimental data on 255 MeV electrons scattering in an ultrathin 0.58 micrometer (111) Si crystal and extended computer simulations put some light on this problem. References 1. O. V. Bogdanov , Y. L. Pivovarov, Y. Takabayashi, T. A. Tukhfatullin, J. Phys.: Conf. Ser. 357 (2010) Article number 012030. 2. Y. Takabayashi, Yu.L. Pivovarov, T.A. Tukhfatullin, Phys. Lett. A 378 (2014) 1520. 3. Y. L. Pivovarov, T. A. Tukhfatullin, J. Phys.: Conf. Ser. 517 (2014) Article number 012028. 4. Y. Takabayashi, V. G. Bagrov, O. V. Bogdanov, Y. L. Pivovarov, T. A. Tukhfatullin, Nucl. Instr. Meth. B. 355 (2015) 188. 5. Y. Takabayashi, Yu.L. Pivovarov, T.A. Tukhfatullin, Phys. Lett. B 751 (2015) 453. 6. N.F. Mott, H.S. Massey. The Theory of Atomic Collisions. London, 1965. 7. R. Newton. Theory of the waves and particles scattering. McGraw-Hill Book Company, 1969 8. D.S.Gemmel. Channeling and related effects in the motion of charged particles through crystals. Rev. Mod. Phys. 46 (1974) 129. 9. L. Živkovi´c, S. Petrovi´c , S. Kossionides, N. Neškovi´c, Phys. Lett. A 286 (2001) 292. 10.A.I.Akhiezer N.F. Shulga. High Energy Electrodynamics in Matter. Gordon and Breach, London, 1995. 11 S.N. Shul'ga, N.F. Shul'ga, S. Barsuk, I. Chaikovska, R. Chehab, arXiv:1512.04601v1 [physics.acc-ph] 14 Dec 2015.

Speakers: Dr Timur Tukhfatullin (National Research Tomsk Polytechnic University), Dr Yuichi Takabayashi (SAGA Light Source)

Slides tukhfatullin_ch2016-1.pdf

15 Channeling and Quasi-characteristic Radiation of the Charged Particles in the Charged Axes of the Ionic Crystals with a Zinc Blende Structure

Peculiarities of channeling and quasi-characteristic radiation of the charged particles in the charged axes of the ionic crystals with a zinc blende structure were investigated

Speaker: Dr Nikolae Maksyuta (Taras Shevchenko Kiev National University, Kiev, Ukraine)

Slides maksyuta_ch2016.pdf

11:00 Coffee break

S1.2: Channeling & Radiations in Crystals

Convener: FRANK ZIMMERMANN (CERN)

16 Effects of spatial coherency in coherent polarization radiation (transition radiation, Cherenkov radiation, parametric X-radiation).

Processes of coherent radiation such as transition radiation, Cherenkov radiation, X-ray parametric radiation generated by «pancake-like» short electron bunches with any angle ψ between bunch axes and it’s velocity were investigated. There was shown that the angle of maximal radiation yield of transition radiation is determined by the tilt angle ψ for all cases even if such an angle is much higher than 1/γ (γ is the Lorentz-factor). The significant distortion of angular distributions is observed for Cherenkov radiation and X-ray parametric radiation also.

Speaker: Prof. Alexander Potylitsyn (Tomsk Polytechnic University)

Slides potylitsyn_ch2016-inv.pdf

17 Non-Dipolarity of Channeling Radiation at GeV Beam Energies

The concept to create a non-conventional intense positron source by application of channeling radiation (CR) generated in a crystalline target by electrons of energy of several GeV was proposed in [1] and experimentally proven later on [2]. In a hybrid-source setup, the generation of radiation in a single radiator crystal is separated from the successive conversion into e+e̶ - pairs in an amorphous target. The simulation of that part of radiation which is connected with the crystalline structure of the radiator presupposes to account for [3] • the realistic continuous potential of the crystal plane or axis considered • the contributions from CR and coherent bremsstrahlung (CB) • the process of dechanneling in thick crystals due to multiple scattering • the non-dipolarity of CR at energies higher than about 1 GeV [4] The latter circumstance is usually neglected in relevant calculations, although non-dipolarity changes the CR spectrum and intensity as well [4] and, therefore, should also influence the positron spectrum. At sufficiently high particle energy, the effect of non-dipolarity pronounces in a coupling of longitudinal and transverse motion of the channeled particles, when at lower energies the transverse motion is assumed to be independent from the longitudinal one and is governed by the continuous potential only. We present a classical method for calculation of CR in the non-dipole case. References 1. R. Chehab, F. Couchot, A. R. Nyaiesh et al., Proc. IEEE PAC’89, Chicago, IL, USA, 1989, p. 283. 2. T. Suwada, M. Satoh, K. Furukawa et al., Phys. Rev. Spec. Topics – Accelerators and Beams 10 (2007) 073501 (and Refs. therein) 3. B. Azadegan, S. A. Mahdipour and W Wagner, Journal of Physics: Conf. Series 517 (2014) 012039. 4. N. F. Shul’ga, L. É. Gendenshteĭn, I. I. Miroshnichenko et al., Sov. Phys. JETP 55(1) (1982) 30 (and Refs. therein)

Speaker: Dr Behnam Azadegan (Hakim Sabzevari University)

Slides azadegan_ch2016.pdf

18 On the influence of the PWO crystal structure on the CMS ECAL performance

It was predicted and observed in 1980-th [1-6] that both electron-positron pair production by gamma-quanta and gamma-quanta emission by electrons and positrons are strongly enhanced at the energies exceeding tens of GeV in oriented crystals. Crystals are widely used in the electromagnetic calorimeters, e.g. the electromagnetic calorimeter ECAL of Compact Muon Solenoid at LHC is made of PWO crystals. In spite of this, the influence of the crystal structure on the process of electron, positron and gamma-quanta energy measurement was neither analyzed, nor taken into consideration in the determination of both the measured energy value and resolution. We will report the first results of simulations of the electromagnetic shower development accelerated by the processes [1-6] in the PWO crystals manufactured for the ECAL CMS. Two samples from the PWO mass production batch have been investigated through the parallel X-ray beam diffraction of the Cu=0.154179 nm line on the Ultima IV diffractometer. Both of them clearly demonstrate the presence of the crystalline structure; however the quality of the latter differs considerably. To estimate the PWO crystal structure influence on the energy deposition, the GEANT4 simulation of electromagnetic shower development in a structureless PWO standard sample routinely implemented in GEANT4 was used as a benchmark. First, the characteristics of both pair production and gamma-quantum emission in the PWO crystal have been evaluated by the method [7,8] for various gamma-quantum and electron (positron) energies. The obtained pair production probabilities and electron (positron) energy loss lengths, increased due to the influence of the PWO crystal structure, have been introduced into the GEANT4 simulations through the increase of the corresponding values for the structureless PWO. These simulations demonstrates that the maximum of the energy deposition by the 100 GeV gamma-quantum is shifted by several radiation lengths while the deposited energy only weakly changes under the influence of the electromagnetic shower acceleration induced by the PWO crystal structure. Obtained results can be used to refine the methods of new particle mass measurements by Compact Muon Solenoid at LHC (CERN). References 1. V.G. Baryshevsky, V.V. Tikhomirov, Sov. J. Nucl. Phys. 36 (1982) 153; Sov. Phys. JETP 58 (1983) 135. 2. V.V. Tikhomirov, Vestn. Belorussk. Univ. Ser. 1, 3 (1983) 27 [in Russian]. 3. V.G. Baryshevsky, V.V. Tikhomirov, Sov. Phys. Uspekhi 32 (1989) 1013. 4. J.C. Kimball, N. Cue, Phys. Rep. 69 (1985) 125. 5. V.N. Baier, V.M. Katkov, V.M. Strakhovenko, Electromagnetic Processes at High Energies in Oriented Single Crystals (World Scientific, Singapore), 1998, 568 p. 6. A.I. Akhiezer, N.F. Shulga, High-Energy Electrodynamics in Matter (Gordon & Breach, New York), 1996, 400 p. 7. V. Guidi, L. Bandiera, V.V. Tikhomirov, Phys. Rev. A86 (2012) 042903. 8. L. Bandiera, E. Bagli, V. Guidi, A. Mazzolari, A. Berra, D. Lietti, M. Prest, E. Vallazza, D. De Salvador, V. Tikhomirov, Phys. Rev. Lett. 111 (2013) 255502.

Speaker: Prof. Alexander Lobko (Institute for Nuclear Problems, Belarusian State University)

Slides lobko_ch2016.pdf

19 Development of a compact laser-free accelerator-driven X-ray source based on channeling radiation

Channeling radiation produced from field-emitted electron bunches accelerated in a compact high-duty cycle accelerator could lead to the development of laser-free rugged X-ray sources [C. A. Brau, et al., Synchrotron Radiation News, 25, Issue 1 (2012)]. This type of source could have application in a variety of domains including in medical imaging and industry. In this paper we present our progress toward the design of such a compact accelerator including high-fidelity simulations of the electron source, its beam dynamics and the channeling radiation process.

Speaker: Philippe Piot (northern Illinois University & Fermilab)

Slides piot_ch2016-1.pdf

20 Induced Resonance Evolution of the channeling electron beam

Induced Resonance Evolution of the channeling electron beam V.V. Ambartsumov1, N.P. Kalashnikov1 1 National Research Nuclear University MEPhI (Moscow Engineering Physics Institute). e-mail: vazgen993@yandex.ru; kalash@mephi.ru Abstract. The motion of channeling particles in the accompanying coordinate system can be considered as one-dimensional oscillator (in the case of planar channeling) or as a two-dimensional atom (in the case of axial channeling) [1-5]. The transversal motion of the channeling particles is characterized by discrete spectrum. The occupation probability of the transversal motion levels depends on the entrance angle of charged particle relative to the crystallographic axis. Passing through the single crystal the charged channeling particle undergoes periodic impact of the lattice atoms [2,6,7] with the main frequency ω= γ v⁄(d,) where is the lattice constant, and γ=E⁄(mc^2 ) are the speed and the Lorentz-factor of the channeling particle [2]. If an external periodic action frequency coincides with the transition frequency of the channeling particles from one quantized state of transversal motion in another, then the resonant excitation of channeling particles is possible. This effect is analogous with the excitation of the atomic electrons by the periodic field of monochromatic electromagnetic waves [7-9]. The resonance conditions are discussed and the dependence of the occupation probability of the transversal motion levels of the channeling particles (electrons) upon the single crystal thickness is analyzed. References Lindhard J. Dansk. Vid. Selsk. Math.-Phys. Medd, 1965, v.34 Kalashnikov N.P. Coherent Interactions of Charged Particles in Single Crystals. (Scattering and Radiative Processes in Single Crystals). Harwood Academic Publishers. London and New York. 1988. Baryshevskii V.G. Channeling, Radiation and Reactions in Single Crystal at High Energies. Minsk. University. (in Russian). 1982. Vorobiev S.A. Channeling of Electron Beams. Energoatomizdat. Moscow (in Russian). 1984. Ryabov V.A. Channeling effect. Energoatomizdat. Moscow. (in Russian). 1994. Okorokov V.V. et.al., Phys. Lett., 1973. A43 3929. Ohtsuki Yoshi-Hiko. Charged Beam Interaction with Solids. Waseda University, Tokyo, Japan. Taylor and Francis Ltd. London and New York 1983. Flugge Siegfried. Practical Quantum Mechanics II. Springer-Verlag. Berlin-Heidelberg-New York. 1971. Landau L.D., Lifshitz E.M. (1977). Quantum Mechanics: Non-Relativistic Theory. v.3 (3-rd ed.). Pergamon Press. ISBN 978-0-08-020940-1.

Speaker: Prof. Nikolay Kalashnikov (National Research Nuclear University Mephi)

Slides kalashnikov-dab_ch2016.pdf

21 Model of the Indirect Compression of Targets under Conditions at an Energy of 1.5 MJ

The possibility of the analysis and interpretation of the reported experiments with the megajoule National Ignition Facility (NIF) laser on the compression of capsules in indirect-irradiation targets by means of the one-dimensional RADIAN program in the spherical geometry has been studied. The results of the simulations are in satisfactory agreement with the measurements and correspond to the range of the observed parameters. The one-dimensional simulation of the compression of the capsule can be useful in establishing the boundary behind which two-dimensional and three-dimensional simulation should be used.

Speaker: Dr Galina Vergunova (Lebedev Physical Institute)

Slides vergunova_ch2016.pdf

13:05 Lunch

S2.1: Channeling & Radiations in Various Fields

Convener: Prof. Alexander Potylitsyn (Tomsk Polytechnic University)

22 Proton and light ion deflection at medium energies with planar bent crystals

Simulations were performed to calculate beam deflection of planar-channeled protons and carbon ions by bent crystals, in the energy range of a few hundreds of MeV/u. With only weekly relativistic particles, deflection angles may reach 10° and above for particles surviving channeling conditions.

Speaker: Dr Denis Dauvergne (Institut de Physique Nucléaire de Lyon)

Slides dauvergne_ch2016.pdf

23 On the measurement of transition radiation characteristics in the prewave zone with the use of restricted parabolic mirror

The present work deals with the problem of transition radiation characteristics measurement in the prewave zone. We consider backward millimeter wavelength transition radiation generated by ultrarelativistic electron during its traversal of thin metallic plate in vacuum. In [1] it was shown that the use of large (much larger than effective transverse size L of electron’s coulomb field at considered wavelength) collecting parabolic mirror with the detector situated in its focal point enables complete elimination of the prewave zone effect for radiation characteristics (broadening of radiation angular distribution and frequency dependence of radiation spectral intensity) and allows obtaining the results which coincide with the ones obtained in the wave zone (which is very convenient since the wave zone may begin far beyond the boundaries of the laboratory). The increase of the electron energy, as well as the choice of larger radiation wavelengths, increases L, which can reach and even exceed the size of the mirror. In this case the conditions considered in [1] (infinitely large mirror) are violated. In the present work we investigate the applicability region of the results obtained in [1] and derive radiation distributions obtained with the use of mirror of arbitrary transverse size. It is shown that even in the case when the mirror size is several times as large as L the position of radiation angular distribution maximum can still be significantly shifted from its ‘wave zone’ position. As a special case a measurement with the use of a ‘point-like’ mirror, which allows defining radiation energy distribution over wave vector directions in a single point of space, is considered. 1) B.N. Kalinin, G.A. Naumenko, A.P. Potylitsyn et al., JETP Letters 84 (2006) 136.

Speaker: Sergii Trofymenko (Kharkov Institute of Physics and Technology)

Slides trofymenko_ch2016.pdf

24 Parametric X-ray radiation in the backward geometry under interaction of relativistic electrons with crystalline and polycrystalline structures

Parametric X-ray radiation generated by relativistic electrons in crystals and polycrystals with different quality of grain structures is studied experimentally. The obtained results are compared with the existing PXR theories for crystalline [1] and polycrystalline structures [2]. A deviation between the existing theories and measurements is observed for textured polycrystals which can be considered as a transition structure between crystals and polycrystals. Nevertheless, the comparison can be performed analysing different parameters such as the mosaic degree of the target, electron multiple scattering in the target and the divergence of the incidence beam of charged particles. The PXR was registered in the backward geometry during the interaction of a 7 MeV electron beam with tungsten, nickel, and molybdenum polycrystalline foils, and highly oriented pyrolytic graphite crystals. The orientation distributions of PXR yield, the PXR peak position and spectral width are analysed. The experimental results are in good agreement with a developed model based on the PXR kinematical theory [3]. References 1. V.G. Baryshevsky, I.D. Feranchuk. Parametric X-rays from ultrarelativistic electrons in a crystal : theory and possibilities of practical utilization, J.Phys.France. 44 (1983) 913-922,. 2. N.N. Nasonov. Collective effects in the polarization bremsstrahlung of relativistic electrons in condensed media, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms. 145 (1998) 19-24. 3. M.L. Ter-Mikaelian. High Energy Electromagnetic Processes in Condensed Media. (1972).

Speaker: Esteban Irribarra (Escuela Politécnica Nacional, Quito, Ecuador)

Slides irribarra_ch2016.pdf

25 Radiation of Non-relativistic Particle on a Conducting Sphere and a String of Spheres

One of the ways to describe diffraction and transition radiation (DR and TR) is the application of the boundary conditions to the solutions of Maxwell equations on the boundary of two media. It becomes evident that the boundary conditions could be satisfied only after addition to the solutions of Maxwell equations with the charge and current of the passing particle the solution of free Maxwell equations that correspond to the radiation field. The conditions on the boundary between vacuum and ideal conductor could be satisfied in some cases via introduction of one or more fictive charges along with the real charged particle; this approach to electrostatic problems is known as the method of images (see, e.g., [1]). Namely the method of images had been used in the pioneering paper [2] where TR on a metal plane had been predicted. The method of images had been used also in [3] for consideration of TR under passage of the particle through the center of the ideally conducting sphere. The radiation arising under motion of the particle with the arbitrary impact parameter to the center of the conducting sphere as well as along the axis of the periodic string of such spheres is considered in the present report. The spectral-angular density of the radiation is computed as well as the radiation spectrum integrated over the radiation directions. Note, particularly, that the spectrum od DR on the metal sphere possesses the maximum under $b\omega/v \approx 2.35$, where $b$ is the impact parameter, $\omega$ is the radiation frequency and $v$ is the incident particle's velocity. So, for the particle with $v=0.1 c$ moving by the sphere with radius $R=20$ nm under the impact parameter $b$ close to $R$ the radiation intensity maximum will lie in the visible domain. This research is partially supported by the grant of Russian Science Foundation (project 15-12-10019). \vspace{1em} \noindent {\bf References} {\footnotesize \noindent [1] J.D. Jackson, Classical Electrodynamics, Wiley, New York, 1999. \noindent [2] V.L. Ginzburg, I.M. Frank, J. Phys. USSR 9 (1945) 353. \noindent [3] G.A. Askaryan, JETP 29 (1955) 388 {\it (in Russian)}. }

Speaker: Prof. Vladislav Syshchenko (Belgorod State University)

Slides syshchenko_ch2016.pdf

26 Cherenkov Radiation from the Target with Predetermined Dielectric Properties, Produced Using 3D-Printer

Most targets from natural and industrial materials, used for Cerenkov radiation (ChR) generation have a refractive index in millimeter wavelength region n> 1.4. It is often a problem to output the radiation from such cylindrical or planar targets because the angle of incidence of ChR on the outer surface of target is greater than the angle of total internal reflection. In this report we present the solution of this problem by usage of 3D-printer for preparation of targets with predetermined dielectric properties. We demonstrate the output of ChR of relativistic electrons from the flat target with the refractive index n=1.29.

Speaker: Dr Gennady Naumenko (Tomsk Polytechnic University)

Slides naumenko_ch2016-1.pdf

27 Radiation from a Wakefield Dielectric Structure with Open End

In recent years, emission of terahertz (THz) electromagnetic waves attracts essential attention of researchers. Radiation in this frequency region can be used for variety of applications, for example, investigation of biology objects, beam diagnostics in accelerators, etc. One recent idea for producing efficient THz radiation consists in passing of specially prepared electron bunch through a wakefield dielectric structure [1]. We utilized several approaches to investigate radiation exiting the open end of such a structure [2,3]. In the present report, we consider the situation where semi-infinite cylindrical waveguide with uniform dielectric filling is placed into collinear infinite vacuum waveguide with larger radius, with dielectric part being excited by a single waveguide mode. We utilize rigorous approach based on mode-matching technique and modified residue-calculus technique [4]. In the issue, we obtain certain nonlinear infinite system which should be solved using iteration process. However, convenient zero-order approximation and asymptotic of the solution are dictated by Meixner’s edge condition, therefore simplifying considerably the numerical procedure. We develop numerical algorithm and obtain structure of reflected and transmitted modes for various frequencies and structure dimensions. We also perform 3D simulation of the described problem using CST code. Obtained results are in agreement within less than one percent accuracy. It is noticeable that our rigorous approach takes around 50 times smaller simulation time compared with CST, and this ratio can be further improved. We also consider more complicated cases of a vacuum channel in dielectric structure and excitation by a point moving charge. Moreover, we calculate radiation from considered structure into free space by supposing that the larger radius waveguide has an open end at some essential distance from the dielectric structure. We show that typically reflection from this end is weak, therefore radiation process can be considered separately on the basis of known mode structure and known rigorous formulas [6]. [1] S. Antipov et al., Appl. Phys. Lett., vol. 100, p. 132910, 2012. [2] S.N. Galyamin et al., Opt. Express, vol. 22, No. 8, p. 8902, 2014. [3] S.N. Galyamin, A.V. Tyukhtin, A.A. Grigoreva, and V.V. Vorobev, in Proc. IPAC’15, pp. 2578-2580. [4] R. Mittra and S. W. Lee, Analytical techniques in the theory of guided waves (Macmillan, 1971). [5] http://www.cst.com [6] L. Weinstein, The Theory of Diffraction and the Factorization Method (Golem Press, 1969). Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913).

Speaker: Dr Sergey Galyamin (Saint Petersburg State University)

Slides galyamin_ch2016.pdf

28 Photoelectric polarization and quantum-chemical data about electrochemical films formed in perchlorate alcohol solutions

The work is held to investigation of alcohol solvent role in the mechanism of electrochemical films formation on the transition metals. Photoelectric polarization data in situ allowed to find that structure and mechanism of the surface layer growth is determined by donor-acceptor interaction between d-metals surface states and dipoles of solvent. They are associated to neutral adsorption-electrochemical complex [MeOHR]0 on the surface of anode. The stoichiometry of films is defined by defects concentration in the crystal lattice formed phase. The states of the crystal field are contributing to the bonding. The results of quantum-chemical modeling of surface complex and anion in individual and coordinated state showed that anion ClO4- was a component of outer-sphere for surface complex.

Speaker: Prof. Angelina Popova (Maykop State Technological University)

Slides popova_ch2016.pdf

16:30 Coffee break

S2.2: Channeling & Radiations in Various Fields

Convener: Prof. Nikolai Shul'ga (Akhiezer Institute for Theoretical Physics of NSC KIPT)

29 Polarization radiation in periodic structures as instrument for hadrons identification in TeV energy range

Various cosmic ray experiments and experiments on modern and future accelerators face the challenge to identify particles with gamma-factors up to ~10^5. For example, widely used transition radiation detectors are good for separation of electrons from the hadron background up to hadron Lorentz-factors of about 500. For higher Lorentz-factor the contribution of transition radiation from hadrons becomes significant and almost reaches saturation at Lorentz-factors of about 3*10^3. The identification of charged particles of ultra-high energies, therefore, is an extremely difficult task and now there are no detectors capable of identifying the single charged particles with reliable efficiency in this range of Lorentz-factors. One of the examples where such type of detectors should play a crucial role is the study of hadron production within small angles at Large Hadron Collider (LHC). This experiment requires separation of protons, K-mesons and pi-mesons in the energy range of 1-6 TeV. Besides measurement of fundamental QCD processes defining particles production with low transverse momentum at LHC energies, these experiments are extremely important for Astroparticle Physics. Such experiments will allow to resolve ambiguities related to the models of particle production at energies up to 10^17 eV in the Universe, where the particle spectrum is observed to change significantly. In this report we discuss the ways to identify the charged particles with ultra-high energies proceeding from the properties of different types of polarization radiation in periodic structures. Resonant transition radiation, parametric x-ray radiation, Cherenkov x-ray radiation and others, as well as the ways of improving of conventional TR-based detectors are estimated from point of view their capability of identifying the charged particles with ultra-high energies. The theoretical consideration is added with Geant4 simulation results.

Speaker: Dr Alexey Tishchenko (National Research Nuclear University "MEPhI")

30 Smith-Purcell radiation from a cylindrical grating

We investigate the radiation from a charged particle rotating around a diffraction grating on a cylindrical surface. The grating consists metallic strips parallel to the cylinder axis. The expressions are derived for the electric and magnetic fields and for the angular density of the spectral-angular distribution of the radiation intensity. The angular density of the radiation intensity is decomposed into the pure synchrotron, Smith-Purcell and interference contributions. Depending on the parameters of the diffraction grating, the interference can enhance or suppress the radiation on a given harmonic. The behavior of the radiation intensity on large harmonics can be essentially different from that for a charge rotating in the vacuum or around a solid cylinder. Unlike to these limiting cases, for the geometry of diffraction grating the radiation intensity on higher harmonics does not vanish for small angles with respect to the cylinder axis. For given characteristics of the charge, by the choice of the parameters of the grating, one can have highly directional radiation directed near the normal to the plane of the charge rotation. With decreasing energy, the relative contribution of the synchrotron radiation decreases and the Smith-Purcell part is dominant.

Speaker: Prof. Aram Saharian (Institute of Applied Problems in Physics NAS RA)

Slides saharian_ch2016.pdf

31 Smith-Purcell radiation from 2D photon crystal

Charged particles moving in periodical structures produce different kinds of radiation, including parametric radiation and Smith-Purcell radiation (SPR), which are rather close in its nature, indeed. The latter is well investigated for different types of gratings like lamellar, eshelette, gratings made of strips, etc. Smith-Purcell radiation from photonic crystals has been studied less. As it was shown in the papers of K. Ohtaka et al. [1-4], in the case of photon crystals the SPR radiation spectrum contains very sharp lines which are inconsistent with the conventional Smith-Purcell dispersion relation. Though the experimental investigations and computer simulations of this phenomenon have been done already, the only theoretical consideration was published in [2], which, however, is also semi-numerical. In this work we report the theory of Smith-Purcell effect for 2D photon crystal. The theory is constructed from the first principles proceeding from Maxwell’s equations and microscopic characteristics of the objects the crystal made from. Two dimensionality “2D” is understood in both ways: photonic crystal is an arranged system of particles, disposed in the one layer (monolayer), with periodicity in two different directions. We consider the local field effects [5, 6] that are necessary for consideration of interaction of the particles. Also, we take into account the effect of conical diffraction in Smith-Purcell radiation [7], and discuss its main spectral and angular characteristics. We show that the effects mentioned are capable of crucial change of the conventional Smith-Purcell radiation properties. 1. S. Yamaguti, J. Inoue, O. Haeberle´, K. Ohtaka, Photonic crystals versus diffraction gratings in Smith-Purcell radiation, Phys. Rev. B 66, 195202 (2002). 2. T. Ochiai, K. Ohtaka, Relativistic electron energy loss and induced radiation emission in two-dimensional metallic photonic crystals. I. Formalism and surface plasmon polariton, Phys. Rev. B 69, 125106 (2004). 3. N. Horiuchi, T. Ochiai, J. Inoue, Y. Segawa, Y. Shibata, K. Ishi, Y. Kondo, M. Kanbe, H. Miyazaki, F. Hinode, S. Yamaguti, and K. Ohtaka, Exotic radiation from a photonic crystal excited by an ultrarelativistic electron beam, Phys. Rev. E 74, 056601 (2006). 4. T. Ochiai, Imitating the Cherenkov radiation in backward directions using one-dimensional photonic wires, Optics Express 18, 14165 (2010). 5. M.I. Ryazanov, A.A. Tishchenko, Clausius-Mossotti-Type relation for planar monolayers, JETP 103, 539 (2006). 6. M.I. Ryazanov, M.N. Strikhanov, A.A. Tishchenko, Local field effect in diffraction radiation from a periodical system of dielectric spheres, Nucl. Instr. and Meth. B 266, 3811 (2008). 7. D.Yu. Sergeeva, A.A. Tishchenko, M.N. Strikhanov, PR STAB 18, 052801 (2015).

Speaker: Ms Darya Sergeeva (National Research Nuclear University "MEPhI")

32 Parametric X-ray radiation in the backward geometry under interaction of relativistic electrons with crystals

Parametric X-ray radiation (PXR) appears during coherent scattering of the charged particle Coulomb field on the atomic structures. PXR was studied theoretically and experimentally in different geometries, in a wide range of charged particles energies and several crystalline targets (crystalline, polycrystalline and multilayer mirrors). Nevertheless, the backward geometry for the PXR observation represents a lacuna where both theoretical and experimental works need to be performed. The presented study is devoted to the PXR research in the backward geometry. The PXR is generated under interaction of a 7 MeV electron beam with highly oriented pyrolytic graphite (HOPG) crystals and a textured tungsten foil. HOPG crystals have mosaic angles 0.4°, 0.8° and 1.7°; the angular size of texture spread for the tungsten target is 5.4°. The PXR spectral peaks for four diffraction orders are observed and the corresponding orientation dependencies are measured for the HOPG crystals. Diffracted photons related to parametric X-ray radiation produced by relativistic electrons are detected below the low energy threshold for the X-ray diffraction mechanism in crystalline structures for the first time for the HOPG crystals and textured tungsten foil. The model developed for the studied process and its comparison with the experiments are presented in the work also. The developed experimental approach can be applied to separate the contributions of real and virtual photons to the total diffracted radiation generated during the interaction of relativistic charged particles with crystalline targets. The work was supported by a Program of the Ministry of Education and Science of the Russian Federation for higher education establishments, Project No. 3.2009.2014/K.

Speaker: Dr Alexander Kubankin (Belgorod National Research University)

Slides kubankin_ch2016.pdf

33 Radiation from a charge rotating inside a cylindrical grating

We investigate the spectral-angular distribution for the radiation emitted by a point charge rotating inside a cylindrical grating with conducting strips. Two types of the radiation processes are realized: synchrotron and Smith-Purcell radiations. Their relative contributions to the total radiation intensity are discussed in various asymptotic regions of the parameters describing the diffraction grating and for large harmonics. The region of the parameters is specified for which the interference effects between the synchrotron and Smith-Purcell radiation is essential.

Speaker: Ms Anna Kotanjyan (Yerevan State University)

Slides kotanjyan_ch2016.pdf

34 Cherenkov and parametric (quasi-Cherenkov) radiations produced by a relativistic charged particle moving through crystals built from metallic wires

The studies of quasi-Cherenkov radiation produced by a charged particle moving through crystal built from parallel metallic wires (wire media) have demonstrated that the intensity of radiation grows essentially when the wavelength becomes comparable with the wire radius (kR~1). Until recently, the interaction of electromagnetic waves with wire media was analyzed in the approximation of isotropic scattering of the electromagnetic wave by a single wire. However, in the range kR~1, electromagnetic wave scattering by a wire is anisotropic, i.e., the scattering amplitude depends on the scattering angle. In this report, we derive the equations that describe diffraction of electromagnetic waves and spontaneous emission of charged particles in wire media, and take into account the angular dependence of scattering amplitude. Numerical solutions of these equations show that the radiation intensity increases as the wire radius is increased and achieves its maximal value in the range kR~1. The case when this condition is fulfilled in the THz frequency range is considered in detail. The calculations show that the instantaneous power of Cherenkov and quasi-Cherenkov radiations from electron bunches in the crystal whose thickness is only 10~cm can be tens--hundreds megawatts, i.e., high enough to allow experimental observation as well as possible practical applications.

Speaker: Mr Evgeny Gurnevich (Research Institute for Nuclear Problems of Belarusian State University)

Slides gurnevich_ch2016.pdf

PS1: Poster Session

Convener: Andrea Liedl (LNF)

35 ABOVE-BARRIER REFLECTION AND DEGENERATE STATES OF ENERGY BAND SPECTRUM IN PLANAR CHANNELING OF ELECTRONS AND POSITRONS IN CRYSTALS

The motion of a charged particle in a one-dimensional periodic potential of the Kronig-Penney type is considered. The energy band structure, Bloch wave functions in coordinate and momentum representation are investigated in detail. Two sharply distinguished groups of states, i.e. below-barrier and above-barrier, are extracted and the role of both of them in the channeling of positively and negatively charged particles is explained. It is shown that only using a dispersion equation form one is able to obtain information on the symmetry properties of the Bloch wave functions at the edges of energy bands. An estimate of the corresponding regions of the edge coherence in the Brillouin zone is given. In the above-barrier case a nontrivial effect is found of parity interchange violation of the Bloch wave functions at the edges of energy bands, connected with the nullification of the reflection coefficient either from the single barrier or well. An oscillatory behavior of both allowed and forbidden band widths is revealed. The analytical results for different values of the parameters are illustrated by computer calculations. The behavior of Bloch wave reflection coefficients from potential barriers and wells for the nearest above barrier energy band as a function of quasi-momentum in the Brillouin zone is investigated for different energies of channeled electrons and positrons. The variation of above-barrier reflection coefficients for the whole energy spectrum at transition from one energy band to another for each fixed energy value of incident particles is also studied.

Speaker: Dr Erine Babakhanyan (National Research Laboratory after A.I. Alikhanian (Yerevan Physics Institute), Armenia)

36 Angular distributions of parametric X-ray radiation from a diamond crystal

When a relativistic charged particle is incident on a crystalline target, parametric X-ray radiation (PXR) is produced in the Bragg direction [1]. This radiation process can be regarded as diffraction of virtual photons associated with the incident particle. Recently, PXR has been studied as a new beam diagnostic method [2-5]. In such studies, measurements of PXR angular distributions are important. We have previously reported the results of such measurements for thin Si crystals [6,7]. The purpose of the present study is to extend this research to diamond crystals. Since diamond is resistant to radiation damage [8], it is a promising material for diagnosing the properties of intense beams. Diamond crystals are also interesting as targets for experiments on optical channeling radiation [9] and Cherenkov radiation [10] because they are optically transparent. The experiments were conducted using a 255-MeV electron beam from the injector linac at the SAGA Light Source (SAGA-LS) in Japan. As a target, a 50-micron-thick diamond crystal was employed. The target crystal was installed on a two-axis goniometer in a vacuum chamber. All experiments were performed using the Laue geometry and the observation angle was 32.2 deg. The Bragg energies were calculated to be 10.9 and 17.7 keV for C(111) and C(220), respectively. X-rays from the crystal were extracted into air through a 250-micron-thick beryllium window. An imaging plate (IP) was used as an X-ray detector [6], and was placed at a distance of 1 m from the crystal. Since IPs offer advantages such as a large detection area, a high spatial resolution, and very good intensity linearity, high-quality data on PXR angular distributions were successfully obtained. The measured PXR angular distributions were compared with those predicted theoretically and good agreement was obtained. The cause of the slight difference observed around the center position (Bragg direction) is also discussed. References 1. M.L. Ter-Mikaelian, High Energy Electromagnetic Processes in Condensed Media, Wiley-Interscience, New York, 1972. 2. Y. Takabayashi, Phys. Lett. A 376 (2012) 2408. 3. Y. Takabayashi, K. Sumitani, Phys. Lett. A 377 (2013) 2577. 4. A. Gogolev, A. Potylitsyn, G. Kube, J. Phys. Conf. Ser. 357 (2012) 012018. 5. G. Kube, C. Behrens, A.S. Gogolev, Yu.P. Popov, A.P. Potylitsyn, W. Lauth, S. Weisse, Proc. of IPAC2013, 2013, p. 491. 6. Y. Takabayashi, A.V. Shchagin, Nucl. Instr. Meth. B 278 (2012) 78. 7. Y. Takabayashi, K.B. Korotchenko, Yu.L. Pivovarov, T.A. Tukhfatullin, Nucl. Instr. Meth. B 315 (2013) 105. 8. R. Schwitters, The SLAC Coherent Bremsstrahlung Facility, SLAC-TN-70-32, 1970. 9. K.B. Korotchenko, Yu.L. Pivovarov, JETP Lett. 103 (2016) 87. 10. Y. Takabayashi, E.I. Fiks, Yu.L. Pivovarov, Phys. Lett. A 379 (2015) 1032.

Speaker: Dr Yuichi Takabayashi (SAGA Light Source)

37 Angular Momentum of Radiation from Relativistic Electrons Channeled in Si and W Crystals

Recently, the effect of mirroring of sub-GeV electrons by a thin Si half-wave crystal (HWC) was experimentally observed and explained by computer simulations [1]. The features of corresponding radiation spectra [2] at HWC channeling are described using the code BCM-1 [3]. This code was also used earlier in calculations of positrons yield using channeling radiation [4]. The first estimation of the orbital angular momentum (OAM) of the radiation from 350 MeV positrons at planar channeling in the thin HWC Si crystal is carried out in [5]. Here, using the developed code BCM-1, the dependence of OAM of the radiation from 155-255 MeV electrons from initial beam energy, angle of incidence and the type of the trajectory is described in detail. The energies of electron beams are chosen according to experimental setup of INFN-LNF (Italy) and SAGA-LS (Japan). The proposed scheme of the production of the radiation carrying OAM allows to generate the twisted photons with much higher energies compared to scheme using the undulator radiation [6]. References 1. T. A. Tukhfatullin, Yu. L Pivovarov, Y. Takabayashi, Phys. Lett. B 751 (2015) 453–457. 2. Y. Takabayashi, V. G. Bagrov, O. V. Bogdanov, Yu. L. Pivovarov, T. A. Tukhfatullin, Nucl. Instr. Meth. B 355 (2015) 188. 3. O.V. Bogdanov, E.I. Fiks, K.B. Korotchenko, Yu.L. Pivovarov, T.A. Tukhfatullin, J. of Phys.: Conf. Ser. 236 (2010) №1; doi:10.1088/1742-6596/236/1/012029. 4. S. V. Abdrashitov, O. V. Bogdanov, S. B. Dabagov, Yu. L. Pivovarov, T. A. Tukhfatullin, Nucl. Instr. Meth. B 309 (2013) 59-62; DOI 10.1016/j.nimb.2013.02. 020. 5. S. V. Abdrashitov, V. A. Bordovitsyn, Yu. L. Pivovarov, TSPU Bulletin 153 (2014) 9–12. 6. J. Bahrdt, K. Holldack, P. Kuske et al, Phys. Rev. Lett. 111 (2013) 034801.

Speaker: Mr Sergei Abdrashitov (National Research Tomsk Polytechnic University)

38 Axial Channeling at Low Energies: Thin structure of quantum states and electomagnetic radiation

It is well known [1-2] that the particle trajectory in a axial symmetric potential U(r), is defined by two-dimensional equation of motion with effective potential Ueff(r)=U(r) + Mz2/2mr2, where m is the particle mass and Mz is its conserved angular momentum. The transversal movement of electrons or positrons in axial channeling mode must be considered in quantum approach based on the Schrödinger equation, but with the realistic averaged atomic axis potentials this problem can be solved only by numerical calculations. In this report we propose a less strict but more easy-to-interpret approach, permitting to analytically consider the quantum characteristics of transversal motion of particles in axial channeling based on Bohr quantization conditions [2]: dUeff(r)/dr =0; Mz= ħn (n = 1, 2, 3,…), where ħ - is the Plank constant. We propose to use a convenient for analytical consideration and quite realistic model potentials for axial channeling parabolic Ue(r) = U0 (2r/d)2 (for positrons) or anti-parabolic Ue(r) = -U0 (1-2r/d)2 (for electrons) with effective depth U0 = kEB , where d equals to the lattice constant, EB= 13,6 eV is the Bohr energy and k is a dimensionless constant ( k ≥2), depending on the type and orientation of the crystal and calculated by means of optimal approximation to numerically calculated realistic potential [3-7] in its effective area. It is shown that at nonrelativistic energies the number of the allowed quantum states for electrons and positrons is limited. For example, in Si, there may be 1-2 states for electrons and 3-4 for positrons. The resonance criterion for capturing of particles into channeling regime in case when the transversal momentum of incident particle is equal to ħ•n (n = 1, 2,...) is introduced. The effect may be detected by observing the increased optical radiation yield at the certain discrete frequencies, corresponding to the distances between the transverse motion energy levels. References: 1. Ferretti Bruno. La Radici Classiche della Meccanica Quantica. Borighieri.Torino.1980.415p. 2. Fermi Enrico. Notes on Quantum Mechanics. A Course Given by E.Fermi at the University of Chicago. 1954. Feynman Richard P. Quantum Electrodynamics. A Lecture Note. W.A. Benjamin. Inc. New York. 1961 3. Lindhard J. Dansk.Vid. Selsk. Math.-Phys. Medd, 1965, v.34. 4. Baryshevskii V.G. Channeling, Radiation and Reactions in Single Crystal at High Energies. Minsk. University. (in Russian). 1982. 256 p. 5. Vorobiev S.A. Channeling of Electron beams. Energoatomizdat. Moscow. (in Russian). 1984.96 p. 6. Kalashnikov N.P. Coherent Interactions of Charged Particles in Single Crystals. (Scattering and Radiative Processes in Single Crystals). Harwood Academic Publishers. London-Paris-New York. 1988. 333p. 7. Ryabov V.A. Channeling Effect. Energoatomizdat. Moscow. (in Russian). 1994.240 p.

Speaker: Prof. Nikolay Kalashnikov (National Research Nuclear University Mephi)

39 Characteristics of radiation in "light" and in conventional undulators. Classical and quantum approaches.

As a rule, an intensity spectrum of undulator radiation (UR) is calculated in the classical approach even for electron energy larger than 10 GeV. Such a spectrum is determined by an electron trajectory in an undulator neglecting by radiation losses. Using the Planck's law, the UR photon spectrum can be calculated from the obtained intensity spectrum both for linear and nonlinear regimes. The electron radiation process in a field of strong electromagnetic wave is considered in the quantum electrodynamics frame (Compton scattering process or radiation in a "light" undulator). Comparison of results obtained by both approaches for the UR spectra generated by 250 GeV electrons in the undulator with the 11.5 mm period has been shown that they coincide with high accuracy. Characteristics of the collimated UR beam (spectrum and circular polarization) were simulated with taking into account the discrete process of photon emission along an electron trajectory in both kinds of undulators. Due to this reason spectral photon distributions as well as the polarization dependence on the photon energy are “smoothed” in comparison with expected one for a long undulator, which is considering for the ILC positron source [1].

Speaker: Prof. Alexander Potylitsyn (Tomsk Polytechnic University)

40 Coherent Parametric X-Radiation: Conditions of Observation

Parametric X-radiation (PXR) is generated by electrons of crystalline target when the projectiles (electrons) pass through the target. The radiation is amplified at the specific directions due to the periodicity of crystallographic structure, i.e. due to diffraction. One of the technical challenges in the commissioning and operation of modern accelerators is the measurement and diagnostics of beams. Transverse beam size diagnostics may be realized based on measurement of PXR angular distribution [1-3]. PXR generated by separate electrons of the beam is coherent at certain distribution of beam particles. As the result, the intensity of PXR could be significantly amplified. This kind of radiation is called Coherent PXR (CPXR). CPXR photon energies is order of keV and wavelength is less than 1 nm. Therefore, the use of CPXR to determine the length of extremely short bunch (order of attoseconds) was suggested. While incoherent PXR was already investigated in details theoretically and experimentally [4], coherent PXR (CPXR) was not observed up to now due to the lack of extremely short electron bunches. In the work the CPXR from single bunch as well as from the train of bunches is considered. The features of CPXR: amplification, suppression and fine structure - are analyzed. Conditions for CPXR generation and observation are discussed. The work was supported by the grant #3761 of Ministry of Education and Science of the Russian Federation within “Nauka” Program. References 1. A. Gogolev, A. Potylitsyn, G. Kube, Journal of Physics: Conference Series 357 (2012) 012018 2. Y. Takabayashi, Physics Letters A 376 (2012) 2408–2412 3. G. Kube, C Behrens, A.S. Gogolev, et al, IPAC 2013: Proceedings of the 4th International Particle Accelerator Conference (2013) 491-493. 4. A.P. Potylitsyn, Electromagnetic Radiation of Electrons in Periodic Structures, Springer, 2010.

Speakers: Prof. Alexander Potylitsyn (Tomsk Polytechnic University), Alexey Gogolev, Dr Anton Babaev (Tomsk Polytechnic University)

41 Coherent production electron - positron pairs in channeled state by photon

The solution of the Dirac equation for the electron (positron) in a continuous potential of the crystal axis taking into account the periodicity of the crystal in the direction of the axis was found [1]. In a present report using those wave functions we theoretical study the coherent photo-production of e +e- pairs by photons in the crystal taking into consideration the effect of channeling of created particles. Calculation shows that channeling of created particles result in a splitting of the coherent peak and changes its position. It is similar to combined effect in coherent bremsstrahlung from electrons and positrons [2-4]. For the first time combined effect in coherent bremsstrahlung from electrons was experimentally recorded in [2]. Theory of this effect was developed in [3] for planar channeled positrons [3] and for axially channeled electrons [4]. 1. H. A. Olsen and Yu.P. Kunashenko, Physical Review A, 56 (1997) 527. 2. K.Yu. Amosov, I.E. Vnukov, G.F. Naumenko, A.P. Potulitsin, V.P. Saruchev, JETP Lett. 55 (1992) 612. 3. Yu.P. Kunashenko, J. Phys: Conf. Ser. 517 (2014) 012029. 4. Yu.P. Kunashenko, Nucl. Instr. Meth. B 355 (2015) 110.

Speaker: Prof. Yuri Kunashenko (National Research Tomsk Polytechnic University; Tomsk State Pedagogical University)

42 Dependence of probability of close collisions of high-energy charged particles in a bent crystal from the orientation of the crystal

An investigation on the probability of close collisions of high-energy charged particles in a bent crystal was carried out. On the basis of analytical calculation and numerical simulation we analyzed the dependence of this probability from the orientation of the crystal with respect to the direction of fast charged particles motion. Comparison of the probability of close collisions was done for three main mechanisms of beam deflection in a bent crystal: planar channeling, volume reflection and stochastic deflection. Peculiarities of the dependence of the probability of close collisions from the orientation of the crystal were explained with a help of random string approximation.

Speaker: Prof. Nikolai Shul'ga (Akhiezer Institute for Theoretical Physics of NSC KIPT)

43 Developing Parallel Application on a Cluster of Personal Computers

Nanoclusters on surfaces are interesting for a wide range of chemical, magnetic, electronic and optical properties. Bimetallic particles can be produced displaying either core-shell structures or forming alloys with, eventually, a segregated surface. The possibilities of synthesis outside equilibrium conditions widely increase the range of possible cluster composition and structure. Such particles can be modelled at the atomic scale allowing detailed comparison with experiment. Such studies are facilitated either by depositing the clusters on surface or embedding them into a matrix. Deposited and embedded particles can be modelled on their turn, at the atomic scale. By accumulating them, it is possible to synthesised nanostructured layers with specific properties. Cluster assembled films are formed by deposition on a surface and such films could be modelled as well. Specifically, clusters on surfaces can be obtained by atomic deposition followed by thermal diffusion. This method applies for atomic species forming islands rather then wetting the surface. Such a method was used, for instance, to produce cobalt clusters on a silver surface. These clusters precipitate preferentially on pre-existing defects, or the atoms form defects at landing, themselves acting as sinks for cluster growth. It is well known from both experiment and modelling that clusters slowing down at supersonic velocities do not fragment upon impact. In particular, the question to know to which extent clusters retain their original characteristics needs an answer when the clusters are considered as possible building blocks for transferring their specific properties to the macroscopic scale. The final system is characterised by a limited penetration of the cluster into the substrate. For study of characteristics of low energy cluster beam deposition (LECBD) processes one of best methods is the computer simulation using Molecular Dynamics. However, in this case the calculation time is dramatically increased with increasing the number of atoms in the studied system. The parallelization of algorithm for simulation of LECBD characteristics results in considerable decreasing the calculation time. The parallelization strategy adopted is a multidimensional domain decomposition of the simulation box using a link cell method and a Verlet list method for each sub-domain independently. The program paradigm is based on explicit massage passing, and the standard Massage-Passing Interface (MPI) was chosen in order to achieve portability.

Speaker: Prof. Akbarali Rasulov (Ferghana Politehnical Institute)

44 Electron radiation due to reflection by the crystallographic planes of crystal.

Small-angle particle reflection at the channeling conditions appear when electron is reflected from the crystallographic planes of the crystal [1]. In this work proved existence of quantum resonances in a small-angle reflection of relativistic electrons by a crystal surface, if the crystallographic planes are parallel to a surface. Calculations were based on Kronig–Penney model of potential. We use the potential of crystallographic planes, based on Doyle-Turner model [2]. As a result, it was obtained that the reflection coefficient specifically depend on the angle of incidence with respect to the surface and relativistic factor of electrons and even shows the existence of the Darwin tables. It is well known that reflection of charged particle should be accompanied by electromagnetic radiation. In the present report we develop the theory of electron radiation at the small–angle reflection at channeling condition (RSARC). The spectral and angular properties of electron RSARC are studied. The polarization of electron RSARC is discussed. We also find approximation formula for electron RSARC that shows that intensity is proportional to the squared modulus of the reflection coefficient. References 1. V.G. Khlabutin, Yu.L. Pivovarov, S.A. Vorobyov, Phys. Lett. 97A (6) (1983) 249525 2. K.B. Korotchenko, Y.P. Kunashenko, Radiation Physics and Chemistry. Vol. 109 (2015) 83-88

Speaker: Prof. Yuri Kunashenko (National Research Tomsk Polytechnic University; Tomsk State Pedagogical University)

45 Experimental study of coherent interaction at high-energy in the presence of crystalline defects

The presence of structural defects in a crystal strongly affects the orientational coherent effects of high-energy charged particles. Indeed, the trajectories of charged particles may be abruptly modified by a dislocation or a stacking-fault, causing the particle to dechannel. Two strips, a bent SiGe strip and a bent lithium niobate strip, were exposed to a 400 GeV/c proton beam at the external linesof CERN Super Proton Synchrotron to study the dependence of coherent interactions on crystalline defects. In spite of low channeling efficiency, the volume reflection maintains a high deflection efficiency for both the crystals. In order to have an insight into the role of dislocations on channeling and volume reflection, computer simulation via DYNECHARM++ Monte Carlo code were worked out. The results of the simulations agree with experimental records, demonstrating that volume reflection is more robust than channeling in the presence of dislocations.

Speaker: Enrico Bagli (FE)

46 Flux Peaking of 7-12 keV Deuterons at Channelling in TiD2 Crystal and Enhancement of Neutrons Yield in d(d,n)3Hе Reaction

The energy dependence of the neutrons yield from d(d,n)3He reaction at deuterons energy 7÷12 KeV in the textured TiD2 target (the micro crystals are aligned mainly along <100> direction) was studied recently in [1] using pulsed plasma Hall accelerator with closed electron current (PHA). In Ref. [2] the authors investigated the neutron yield in the same reaction using textured CVD-Diamond and 30 KeV deuteron beam from HELIS accelerator with small angular and energy divergences. The authors of [1-2] suggested that the observed enhancement of neutron yield is connected both with the screening and channeling effects. To clarify the role of channeling in enhancement of neutrons yield in d(d,n)3He reaction in TiD2 crystal target, we present here the results of computer simulations. The deuterons trajectories in a TiD2 crystal are simulated using the computer code Basic Channeling with Mathematica™ (BCM-1) [3], which allows calculate angular and spatial distribution of channeled particles in a thin crystals, see e.g. [4]. The simple model to calculate the reaction yield revealed the remarkable orientation effect directly connected with flux-peaking of deuterons in a crystal. The comparison with experimental data [1] is performed. References 1. V.M. Bystritsky, Vit.M. Bystritskii, G.N. Dudkin, et. al., Nucl. Instr. and Meth. in Phys. Res. A 764 (2014) 42. 2. A.V. Bagulya, O.D. Dalkarov, M.A. Negodaev, Nucl. Instr. and Meth. in Phys. Res. B 355 (2015) 340. 3. O. V. Bogdanov, E. I. Fiks, K. B. Korotchenko, Yu. L. Pivovarov, T. A. Tukhfatullin, J. Phys.: Conf. Ser. (2010) art. No 012029. 4. Y. Takabayashi, Yu.L. Pivovarov, T.A. Tukhfatullin, Phys. Lett. B 751 (2015) 453.

Speakers: Dr Sergey Kuznetsov (Tomsk Polytechnic University), Dr Timur Tukhfatullin (National Research Tomsk Polytechnic University)

47 Influence of incoherent scattering on stochastic deflection of high-energy negative particle beams in bent crystals

An investigation on stochastic deflection of high-energy negatively charged particles in a bent crystal was carried out. On the basis of analytical calculation and numerical simulation it was shown that it exists a maximum angle at which most of the beam is deflected. The existence of a maximum, which is taken in the correspondence of the optimal radius of curvature, is a novelty with respect to the case of positively charged particles, for which the deflection angle can be freely increased by increasing the crystal length. This difference has to be ascribed to the stronger contribution of incoherent scattering affecting the dynamics of negative particles that move closer to atomic nuclei and electrons. We therefore identified the ideal parameters for the exploitation of axial confinement for negatively charged particle beam manipulation in future high-energy accelerators, e.g., ILC or muon colliders. The report is supported by the State Fund for Fundamental Research (project No F64/17-2016).

Speaker: Prof. Nikolai Shul'ga (Akhiezer Institute for Theoretical Physics of NSC KIPT)

48 Multicrystal Microundulator

Radiation of charged particles passing through a set of equidistant ridges on the surface of a single crystal is analyzed. The ridge thickness is a half of the particle trajectory period at channeling in a thick crystal. Passing through such set of half-wave crystals the particle can move on quasi-undulator trajectories [1]. Properties of radiation emitted by swift positrons from such “multicrystal microundulator” are calculated. Such structure can be created on crystal surface, as in [2]. References 1. S.Vorobiev, V.Kaplin, E.Rozum. Patent SU 876044 А. 1980. 2. V.Kaplin, S.Uglov, V. Zabaev, et al. NIM A 448 (2000) 66.

Speaker: Dr Julia Janz (Tomsk polytechnic university)

49 Orientation Effect in d(d,n)3Hе Reaction Initiated by 20 keV Deuterons at Channeling in Textured CVD – Diamond Target

In Ref. [1] the authors investigated the neutron yield in the d(d,n)3Hе reaction using textured CVD-Diamond and 20 keV deuteron beam from HELIS accelerator which delivers the deuteron beam with small angular and energy divergences. The authors of [1] suggested that the observed enhancement of neutron yield is connected both with the screening and channeling effects. To clarify the role of channeling in enhancement of neutrons yield in d(d,n)3He reaction in CVD-Diamond crystal target, we present here the results of computer simulations. The deuterons trajectories in a CVD microcrystal are simulated using the computer code Basic Channeling with Mathematica™ (BCM-1) [2], which allows calculate angular and spatial distribution of channeled particles in a thin crystals, see e.g. [3]. The simple model to calculate the reaction yield revealed the remarkable orientation effect directly connected with flux-peaking of deuterons in a crystal. The comparison with experimental data [1] is performed. References 1. A.V. Bagulya, O.D. Dalkarov, M.A. Negodaev, Nucl. Instr. and Meth. B 355 (2015) 340. 2. O. V. Bogdanov, E. I. Fiks, K. B. Korotchenko, Yu. L. Pivovarov, T. A. Tukhfatullin, J. Phys.: Conf. Ser. 236 (2010) Article number 012029. 3. Y. Takabayashi, Yu.L. Pivovarov, T.A. Tukhfatullin, Phys. Lett. B 751 (2015) 453.

Speaker: Dr Timur Tukhfatullin (National Research Tomsk Polytechnic University)

50 PXR: estimations for the maxima intensity and temperature dependence

The work is devoted to features of parametric X-ray radiation - PXR. On the base of the results obtained in [1] and [2] (and confirmed experimentally in [3]), it is noted that the dependence of maximum intensity on electrons energy for PXR and PXR at channeling (PXRC) is very different. The cause is in band structure of energy levels transverse motion. The relative difference between the intensities of the PXR and PXRC has sharp jumps. Such unusual kind of the theoretical dependence of the relative difference between PXR and PXRC means that even from the theoretical point of view the PXRC intensity measurements will necessarily have scattered values (in contrast to PXR) – for (110) Si – up to 5% Two approximate formulas were obtained for calculation of PXR intensity maximums. The errors of these formulas do not exceed 2.5 % and 1.2 % respectively. For Fourier-components of susceptibility χ0 and χgσ of Si crystal simple formulas are obtained by fitting of data from [4]. These formulas allow calculate χ0 and χgσ with sufficient precision for a wide range of frequencies. Using Debye theory we have took into account the temperature dependence of Fourier components of susceptibility what have led to a small change in PXR intensity. For the range of temperatures of the crystal from 100 K to 1000 K, the intensity variation will not exceed: 3% for T = 100 K and 10% for T = 1000 K. If we take into account change of PXR-photon energy (due to the change of the lattice constant with temperature), for the range of the crystal temperatures from 100 K to 700 K PXR intensity change is very noticeable ~ 86%. 1. R. Yabuki, H. Nitta, T. Ikeda, and Y. H. Ohtsuki, Phys.Rev. B 63, 174112 (2001). 2. K. B. Korotchenko, Y. L. Pivovarov, and Y. Takabayashi, JETP Letters (2012) 95(8) 433–437. 3. K. B. Korotchenko, Yu. L. Pivovarov, and Y. Takabayashi, Nucl. Instr. Meth. B 309 (2013) 25-29 4. S. Stepanov, X-Ray Server, Argonne National Laboratory, Available at http://x-server.gmca.aps.anl.gov

Speaker: Mr Yuri Eykhorn (National Research Tomsk Polytechnic University)

51 Quantum Dynamics of Positrons in the Channeling in Carbon Nanotubes

The positrons quantum channeling in carbon nanotubes by the numerical solution of the Schrödinger equation in the corresponding paraxial approximation is considered. The spatial redistribution of the positrons flux in the transverse plane during channeling in nanotubes is detected. Also the angular distribution of positrons passed through the nanotube is studied. This distribution is sensitive to the transverse structure of nanotubes or CNT bundles. The continuum interaction potential of the positron and nanotube is obtained as a sum of continuous potentials of individual atomic chains [1]. In general, such a potential for of CNTs does not have azimuthal symmetry. For the potential of the interaction between the positron and the carbon atom we use Doyle-Turner approximation. There are various methods for integration of time-dependent Schrodinger equation [2-4]. For the numerical integration of the Schrödinger equation we have considered the evolution operator splitting method based on the Trotter formula [5]. The initial positron beam is represented as a wide Gaussian wave packet in tranverse plane.The calculations on the grid are performed by the transition to the momentum representation using fast discrete Fourier transform algorithms. The wave function evolution was considered on a square computation domain on the transverse plane, large enough so that the interaction of the wave packet with the nanotube walls was going far away from the boundaries of the computation domain. In order to avoid the non-physical wave packet reflections at the grid boundaries an imaginary absorbing potential is introduced. References 1. N.K.Zhevhago, V.I.Glebov, Journal of Experimental and Theoretical Physics, 91, Issue 3 (2000) 504. 2. R.Kosloff, J.Phys. Chem. 92 (1988) 2087. 3. T.N.Truong, J.J.Tanner, P.Bala, J.A.McCammon, D.J.Kouri et al., J.Chem.Phys. 96, (1992) 2077. 4. M.Ćosić, S. Petrović, N. Nešković, Nucl. Instr. and Meth. in.Phys. Res. B323 (2014) 30. 5. H.F. Trotter, Proc. Amer. Math. Soc. 43 (1959) 545.

Speaker: Dr Anatoly Sabirov (Chuvash State University, Cheboksary, Russia)

52 Quantum effects for particles channeling in a bent crystal

Quantum mechanical theory for channeling of relativistic charged particles in the bent crystals is considered. Quantum effects of underbarrier tunneling are essential when the radius of the crystal channel curvature is close to its critical value. In this case the wave functions of the quasi-stationary states corresponding to the particles captured in a channel can be presented in the analytical form. The efficiency of channeling of the particles and their angular distribution at the exit crystal surface are calculated. Characteristic experimental parameters for observation of the quantum effects are estimated. It is shown that thin structure of angular distribution in the deflected beam should appear in the framework of the quantum-mechanical effects for the particles channeled by the bent crystal. Its characteristic form depends on the number of a particle localized states in the average potential of the planes. Experimental investigation of this phenomenon may demonstrate the quantum-size effects for high energy physics and may be useful for optimization of bent crystal parameters. In case, when a crystal curvature radius is near critical one, the quantum tunneling of the captured particles should be taken into account together with the classical de-channeling processes.

Speaker: Prof. Alexander Lobko (Institute for Nuclear Problems, Belarusian State University)

53 Raman Scattering of Photons by the Channeling Electrons

Raman Scattering of Photons by the Channeling Electrons Badreeva D.〖R.〗^1, Kalashnikov N.〖P.〗^1 1 National Research Nuclear University MEPhI, Moscow, Russia dinkulenok@yandex.ru; kalash@mephi.ru Abstract. The motion of channeling particles in the accompanying coordinate system can be considered as a two-dimensional atom in the case of axial channeling. The transversal motion of the channeling particles is characterized by discrete spectrum. The occupation probability of the transversal motion levels depends on the entrance angle of charged particle relative to the crystallographic axis [1-3]. In the scattering of a photon by the "quasi-bound" charged particle in the axial channeling mode, the frequencies which are a combination of the incident photon frequency ω_0and the frequency ω_if (ω_if is the transition frequency in transverse quantized motion of the channeling electron: ω =ω_0± ω_if, where ω_if=2Δε_if γ^2; where γ=E⁄(mc^2 ) is the Lorentz-factor of the channeling electron) would make appearance. In the report the criteria for choosing an adequate continuous potential of the crystallographic axis are discussed [4]. The dependence of the occupation probability of the transversal motion levels of the channeling particles (electron) upon the single crystal thickness is investigated [1-2]. The peculiarities of the Raman scattering spectrum of photons by electrons in the axial channeling regime are analyzed. The possibility of anti-Stocks lines in the Raman spectrum is considered. References 1. Lindhard J. Dansk. Vid. Selsk. Math.-Phys. Medd, 1965, v.34 2. Kalashnikov N.P. Coherent Interactions of Charged Particles in Single Crystals. (Scattering and Radiative Processes in Single Crystals). Harwood Academic Publishers. London and New York. 1988. 3. Ohtsuki Y.-H. Charged Beam Interaction with Solids. Waseda University, Tokyo, Japan. Taylor and Francis Ltd. London and New York. 1983. 4. Kalashnikov N.P., Krokhin O.N. Quantum Electronics. 2014. v.44 (№12). p.p.1109-1111.

Speaker: Prof. Nikolay Kalashnikov (National Research Nuclear University Mephi)

54 Resonance Interaction of the Laser Radiation with thin Structure of axial channeling particles energy levels

In the recent publication [1] the authors had considered the resonance interaction of the laser radiation with ultra-relativistic electrons in planar channeling regime. The idea of the effect was simple: even though the distances between energy levels of channeled electrons and the energies of laser photons may belong to different ranges the Doppler effect bring may help them to match each other when a laser beam is directed right in opposite direction than an electron beam. The same effect is possible also in axial channeling regime. But due to spin-orbital interaction there is also another possibility. The splitting of axial channeling energy levels due to spin-orbital interaction is not large (ΔE ~ 10-4eV ), but the Doppler effect may help the optical laser radiation to match with this splitting in case if the laser beam is directed in the same direction as the electron beam. The possibility and conditions under which it may be to observe this effect, which may result in reemitting of resonantly captured photons with higher energies (due to the Doppler effect) are considered. References: 1. Kalashnikov N.P., Olchak A.S., Khangulian E.V. Radiation from Channeling Electrons, Stimulated by Laser Beam. Nuclear Instruments and Methods. NIM B309, p.p. 67-69. 2013. ref. number NIMB59336

Speaker: Prof. Nikolay Kalashnikov (National Research Nuclear University Mephi)

55 Specific Features of Photonuclear Reactions Yield Induced by Channeling Radiation from Relativistic Electrons

The sub-GeV – several GeV electrons channeling radiation (CR) spectrum is characterized by a brilliant maximum at photon energies up to several MeV [1], depending on electron beam energy. This is enough to excite separate nuclear levels (tens or hundreds KeV) and to excite reaction on light Be and D nuclei and even may reach the region of giant dipole resonance (7-8 MeV) in more heavier nuclei in the downstream target. In this photon energy region the CR photon number exceeds by decades that of bremsstrahlung (BS) if the radiator thickness is the same. This can be an advantage to use CR instead of tradiational BS in studies of photonuclear reactions, as well as for generation of pulsed neutron beams at electron accelerators. Detailed calculations based on simulated CR spectra (simulation procedure is described in detail in [3-4]) reveal the non-trivial dependence of the CR- induced photonuclear reactions yield on the energy of incident electron beam as well as on electron beam alignment with respect to the crystal channeling planes. References [1] Baier V. N., Katkov V. M. and Strakhovenko V. M. Electromagnetic Processes at High Energies in Oriented Single Crystals. World Scientific, Singapore,1998 [2] Bogdanov O.V., Korotchenko K.B., Pivovarov Yu.L. J. Phys. B. 41 (2008) 055004– P.1-8. [3] Bogdanov O.V., Korotchenko K.B., Pivovarov Yu.L. and Tukhfatullin T.A. Nuclear Instruments & Methods in Physics Research B. – 2008.– V. 266.– P. 3858-386. [4] Abdrashitov S. V., Bogdanov O. V., Dabagov S. B. , Pivovarov Y. L. , Tukhfatullin T. A. Nuclear Instruments & Methods in Physics Research B. – 2013 - Vol. 309. – p. 59-62

Speaker: Dr Oleg Bogdanov (TPU&amp; TSU)

56 STIMULATED RESONANCE RADIATION OF CHANNELING PARTICLES

Stimulated Resonance Radiation of Channeling Particles 1,2,3 Dabagov S.B., 2 Kalashnikov N.P. 1 Laboratori Nazionale di Frascati, Istituto Nazionale di Fisica Nucleare, Italy. 2 National Research Nuclear University MEPhI (Moscow Engineering Physics Institute), Moscow, Russia. 3 RAS, P.N. Lebedev Physical Institute, Moscow, Russia Abstract. The motion of channeling particles in the accompanying coordinate system can be considered as an one-dimensional oscillator (in the case of planar channeling), or as a two-dimensional atom (in the case of axial channeling [1]). The transversal motion of the channeling particle is characterized by discrete spectrum. The occupation probability of transversal motion levels depends on the entrance angle of charged particle relative to the crystallographic axis [2-4]. Passing through the crystal charged channeling particle undergoes periodic action of the lattice atoms [5-7] with basic frequency ω= γ v/d, where d is the lattice constant, v and γ are the velocity and the Lorentz factor of the channeling particles [6]. If the frequency of an external periodic interference coincides with the frequency of the transition of the moving channeling particles from one quantized state of transversal motion in another, the resonant excitation of the channeling particles is possible, i.e. similar to the excitation of atomic electrons by the periodic field of monochromatic electromagnetic waves [8-9]. In the report the resonance conditions are discussed and the induced resonance radiation spectrum of channeled particles is analyzed. References 1. Baryshevskii V.G. Channeling, Radiation and Reactions in Single Crystal at High Energies. Minsk. University. (in Russian). 1982. 2. Vorobyov S. Channeling of electron beams. М.: Energoatomizdat. (in Russian). 1984. 3. Ryabov V. Channeling Effect. M.: Energoatomizdat. (in Russian). 1994. 4. Ohtsuki Y.-H. Charged beam interaction with solids. Taylor and Francis Ltd. London - New York 1983. 5. Ter-Mikaelyan M. High energy electromagnetic processes in condensed media. John Wiley and Sons,Inc., New York, 1972. 6. Kalashnikov N.P. Coherent Interactions of Charged Particles in Single Crystals. Harwood Academic Publishers. London-Paris-New York. 1988. 7. Ferretti B. Nuovo Cimento. 1950 v. 7. p. 1-17. Sulla bremsstrahlung nei cristalli. Nuovo Cimento. 1972. v. 7B. No. 2. p. 225-239. Multiple coherent bremsstrahlung of electrons in crystals. Nuovo Cimento. 1972. v. 9 B. p. 399-413. The reduction of the coherence area of high-energy electrons in passage through a crystal. 8. Berestetskii V. B., Lifshitz E. M., Pitaevskii L.P. Quantum Electrodynamics. Butterworth-Heinemann, 1982. 9. Akhiezer A.I., Shulga N.F. Electrodynamics in Matter at High Energies. Academic Publishers. Science. (in Russian). 1991.

Speakers: Prof. Nikolay Kalashnikov (National Research Nuclear University Mephi), Sultan Dabagov (LNF)

57 The formation of protonium atoms at channeling of antiprotons in a hydride lithium crystal

The formation of protonium atoms at channeling of antiprotons in a hydride lithium crystal is investigated

Speaker: Dr Nikolae Maksyuta (Taras Shevchenko National University of Kiev, Ukraine)

58 Z-dependence of PXR for light and heavy ions

As it was shown in [1], the radiation intensity of Parametric X-ray Radiation (PXR) for the different types of accelerated nuclei is proportional to Z2. I our work the same problem is solved for ions. However, in contrast to [1] to calculate PXR radiation intensity, we have used the formula, obtained from the dynamical theory [2] within the framework of multipath approach developed by Ohtsuki (see, for example, [3]). It had allowed us to show that for ions not only PXR-photon frequency, but in addition the shape of PXR angular distribution will change with three parameters: Z, N (number of neutrons in nucleus) and Ze (number of ion’s electrons). Consequently, the Fourier components of the dielectric susceptibility of the crystal will be changed as well. However, all of these features should formally be observed also for nuclei. But these changes are insignificant. The factor causing measurable changes of PXR radiation intensity for ions is the electron screening effect of nuclear charge. On the basis of Thomas-Fermi-Dirac theory we have received by numerical analysis that PXR radiation intensity for ions is proportional to Zo2+1/2Zo, where Zo = Z – Ze is the ion charge. 1. Yu. L. Pivovarov , Yu. P. Kunashenko, and S. A. Vorobiev, Radiation Effects, (1986) 100 51-59. 2. R. Yabuki, H. Nitta, T. Ikeda, and Y. H. Ohtsuki, Phys.Rev. B 63, 174112 (2001). 3. Y. H. Ohtsuki, Charged Beam Interaction with Solids (1983).

Speaker: Prof. Konstantin Korotchenko (TPU)

Tuesday, 27 September

S2.3: Channeling & Radiations in Various Fields

Convener: Prof. Hartmut Backe (Institute for Nuclear Physics)

59 Plans for X- and gamma-ray production at Fermilab Accelerator Technology & Science Facility

The Fermilab Accelerator Technology & Science (FAST) facility currently under commissioning couples a high-brightness electron source with a superconducting linear accelerator (linac) and compact storage ring. The infrastructure is expected to provide a testbed for Accelerator Science and Beam Physics. An active area of research regards the production of X-ray and gamma-ray radiation via respectively channeling and inverse Compton scattering. Wedding these radiation mechanisms to high-repetition-rate linac is expected to provide unprecedented radiation properties (e.g. flux, and brilliance). This talk details our experimental plans and current status together with discussing other research opportunities enabled at the FAST facility.

Speaker: Philippe Piot (Fermilab & Northern Illinois University)

Slides piot_ch2016-inv.pdf

60 Derivation of the classical radiation amplitude from stimulated emission

The classical amplitude of the radiation by a charged particle in non-uniform motion is usually derived from the Lienard-Wiechert retarded potential. It can be derived in a simpler way using the concept of classical simulated emission.

Speaker: Mr Xavier Artru (Université de Lyon, CNRS/IN2P3, IPNL)

Slides artru_ch2016-2.pdf

61 Types of Interference in Highly Non-Dipole Radiation Spectra

Generic structure of spectra of non-dipole radiation from ultra-relativistic electrons is discussed on two examples: 1. Radiation accompanying double hard scattering of an electron with a time interval T. 2. Passage of an electron through a domain of uniform magnetic field of finite length T. In both cases, we will assume that electron deflection angles are small compared to unity, but much greater than electron's Lorentz factor. It is demonstrated that under such conditions, there emerges an hierarchy of photon frequency scales, and the spectrum can be presented as a sum of terms (some of which split in two factors), depending on a single scale of omega, i.e., related with a particular type of a coherence length. As a whole, there can be distinguished three types of coherence length: ``free", deflection angle dependent, and transverse. The spectrum at double hard electron scattering involves two types of oscillations: collinear-collinear interference (from two ends of a ``semi-bare electron" state), and soft-collinear interference (between collinear radiation from one of the external electron lines and soft radiation from the adverse trajectory break). For the spectrum at electron passage through a finite magnet, there are only oscillations due to soft-collinear interference, since there is no straight ``semi-bare electron" segment. In the latter case, the spectrum can be divided into a synchrotron-like component proportional to the magnet length T, and boundary contributions independent of T. The separation into volume and boundary contributions, as well as the soft-collinear interference, should be present also for electron passage through other targets, such as thin crystals or an amorphous target of thickness T.

Speaker: Dr Micola Bondarenco (Kharkov Institute of Physics and Technology)

Slides bondarenco_ch2016.pdf

62 Towards the detection of strong field, Volkov resonances in electron-laser interactions

A theoretical and phenomenological consideration is given to higher order, strong field effects in electron/laser interactions. A consistent strong field theory is the Furry interaction picture of quantum field theory [1,2]. In this theory, fermions are embedded in the strong laser field and the Volkov wavefunction solutions that result, are exact with respect to the strong field [3,4]. When these Volkov fermions interact with individual photons from other sources, the transition probability is enhanced in a series of resonances when the kinematics allow the virtual fermion to go on-shell [5,6]. In order to move towards an experiment that detects these resonances, a simple analytical description of these Volkov resonances is required. Recent work allows a simple form for Volkov traces, using Fierz relations and strong field Ward identities. Volkov resonances are understood in terms of bound or excited strong field states that decay according to the strong field self-interaction of virtual fermions. When these insights are applied to the Furry picture, 2 vertex Compton scattering, a clear description of Volkov resonances results. All of this is reported on, including the experimental set-up required to detect these new, theoretically predicted, phenomena. References [1] S. Schweber. An introduction to Relativistic Quantum Field Theory, section 15g. [2] A. Hartin, EPJ C 71:1729, appendix A (2011) [3] D.M. Volkov, Z. Phys 94:250 (1935) [4] A. Hartin, Phys. Lett. B., 743:166 (2015) [5] V.P. Oleinik, Sov. Phys. JETP, 25(4):697 (1967) [6] V.P. Oleinik, Sov. Phys. JETP, 26(6):1132 (1968)

Speaker: Anthony Hartin (University of Hamburg)

Slides Hartin_Channeling2016_talk.pdf

63 Polarization Tensor of a Photon in an Electric Field

The propagation of a photon is investigating in a constant and uniform electric field at any photon energy. The investigation is based on the polarization operator of a photon in an electromagnetic field [1]. The imaginary part of the polarization tensor eigenvalues gives the partial contribution to the probability of electron-positron pair creation and defines the photon lifetime. The real part describes the dispersive properties of the space region with an electric field. At high energy, the standard quasiclassical approximation is valid. The corrections to this approximation are found. In the region of relatively low photon energies, where these corrections become significant, another approximation is used. This approach is valid at the energy of photon sufficient larger than the “vacuum” energy = eEℏ/mc in electric field. Note, the exponential factor is present in the expression for the probability at this energy, and the exponent is proportional to the ratio of the photon energy to the vacuum energy. In this case, we can talk about the birth of a pair by laser and electric fields in conjunction. When the photon energy is much less than the vacuum energy, the found probability describes the absorption of a soft photon by electron and positron created by an electric field on the formation length of process . Then, the probability under consideration gives the correction to the probability of pair creation by an electric field only. The crossing process is the radiation of a photon by electron and positron created by an electric field. The integral probability of the last process is connected with radiative corrections to the imaginary part of the vacuum loop in an electric field.

Speaker: Prof. Valeriy Katkov (Budker Institute of Nuclear Physics)

Slides katkov_ch2016.pdf

64 Kinetics of relativistic electrons passing through quasi-periodic fields

We report a novel method for evaluating the energy spectrum of electrons emitting hard x-rays and gamma-rays in undulators and Compton sources. The method takes into account the quantum nature of recoils undergone by the electrons emitting high energy photons. The method is susceptible to evaluate a spectrum of electrons for the whole range of the emission rates per electron-pass through the driving force, from much less than one emitted photon in average (Compton sources and short undulators) to many photons emitted (long undulators, relatively low-energy electrons). As is shown, in the former limiting case the spectrum of electrons reflects the spectrum of emitted radiation whereas it is close to the Gaussian shape in the latter case. Limitation of coherency for the sources of high-energy electromagnetic radiation caused by recoils from emitted photons is discussed.

Speaker: Dr Eugene Bulyak (NSC KIPT)

Slides bulyak_ch2016.pdf

65 Muon Beam Channeling in Laser Standing Wave

The problem of muon channeling in a standing wave lattice formed by electromagnetic waves is considered. Possible applications of this effect in accelerator physics are discussed. The charged particles motion in the field of standing electromagnetic wave can undergo the features similar to well-known phenomenon of particles channeling in crystals [1]. While a charged particle enters the field of electromagnetic standing wave at a small angle to the node (anti-node) surfaces its motion represents namely the oscillations between two neighboring surfaces similar to those that take place at crystal planar channeling. The work demonstrates that this effect could be used in accelerator physics for the beam shaping with certain properties. The advantage of particle channeling in a laser field is in the absence of inelastic scattering taking place in a solid matter. Especially, the use of the laser standing wave could be attractive for muon beams (for instance, beams of the neutrino factories projects [2]). The quality of muon beams still needs to be essentially improved. Channeling is one of the known techniques, which proposes efficient beam shaping, however, in the case of crystal channeling the particle scattering by both atoms and electrons of the solids could significantly worsen the beam characteristics. This work presents some results of our analysis for the muon beam channeling in the field of a laser standing wave. In the paper for the first time the evolution of a muon beam in the phase space has been evaluated aiming at the beam shaping feasibility. Various examples of the beam shaping are considered for top-flat as well as Gaussian laser pulses. References 1. S.B. Dabagov, A.V. Dik and E.N. Frolov, Phys. Rev. Special Topics – Accelerators and Beams 18, (2015) 064002. 2. M.S. Zisman, J. Phys.: Conf. Ser. 408 (2013) 012002.

Speaker: Dr Anton Babaev (Tomsk Polytechnic University)

Slides babaev_ch2016.pdf

11:00 Coffee break

S3.1: X-Rays/Neutrons/Atoms Channeling

Convener: Mr Evgenii Frolov (LPI RAS and NR TPU)

66 XRF Imaging Based on Polycapillary Optics

Kouichi Tsuji, Shota Aida, and Yuki Takimoto Graduate School of Engineering, Osaka City University (OCU), 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan A non-destructive elemental imaging is important for environmental, forensic, and material sciences. We will introduce a few approaches for x-ray elemental and chemical imaging in the laboratory at OCU. The drawback of the scanning type XRF imaging would be a long acquisition time. Thus, a projection type XRF imaging has been studied. In my laboratory, we have developed WD-XRF imaging spectrometer using WDS spectrometer, a straight polycapillary optics, and x-ray CCD camera [1,2]. The advantage of WD-XRS is a high energy-resolution, approximately 40 eV [2]. Recently, we applied this technique for observation of corrosion process of metals in the acid solution. In addition, we have studied full-field energy-dispersive type XRF (FF-ED-XRF) imaging spectrometer by taking useful advices from Dr. Romano [3]. In my presentation, the comparison of these XRF imaging techniques will be discussed. In all the cases, the straight type polycapillary optics play an important role for taking the XRF 1 : 1 images. References 1. K. Tsuji, T. Ohmori, M. Yamaguchi, Wavelength Dispersive X-ray Fluorescence Imaging, Anal. Chem., 83 (2011) 6389-6394. 2. K. Tsuji, et al., Spectrochim. Acta Part B, 113 (2015) 43-53. 3. F.P. Romano, C. Caliri, L. Cosentino, S. Gammino, L. Giuntini, D. Mascali, L. Neri, L. Pappalardo, F. Rizzo and F. Taccetti, Anal. Chem, 86, (2014) 10892-10899.

Speaker: Prof. Kouichi Tsuji (Osaka City University)

Slides tsuji_ch2016.pdf

67 2D-3D μXRF Elemental Mapping Reconstruction on Archeological Samples

"Rainbow X-Ray" (RXR) is a μXRF station at "XLab-Frascati", now open for users and optimized for any kind of analytical research field using X-ray sources. In collaboration with two archeological groups (site "Grotta Romanelli" - Late Pleis- tocene, and site "Gran Carro" - Iron Age) we are starting X-ray Fluorescence studies on local artifacts. The elemental analysis of these artifacts (in particular focalizing the analysis on the inclusions) allows us to understand the provenience of the raw materials: superficial (2D) and bulk (3D) micro-fluorescence mapping can provide useful informa- tions for the geologists in order to identify the possible artifacts origins. The results presented in this work are a part of a more wide anthropological/archeological study that is indispensable to understand the social and economical relations of these prehistorical communities.

Speaker: Dariush Hampai (LNF)

Slides hampai_ch2016.pdf

68 X-ray radiation for beam diagnostics

For many years, the optical transition radiation (OTR) was successfully applied for beam diagnostics. However, distortions of the OTR images appear at decreasing of the beam size and increasing of beam current because of diffraction and coherent effects. The influence of these effects can be suppressed using the radiation in the X-ray range. In the present paper, the possible application of a few kinds of X-ray radiation to observe the beam profile is analyzed. The fields of applicability of characteristic X-ray radiation, parametric X-ray radiation, and diffracted transition X-ray radiation are found and discussed.

Speaker: Dr Alexander Shchagin (Kharkov Institute of Physics and Tecknology)

Slides shchagin_ch2016-2.pdf

69 Focusing properties of X-ray radiation channeling at the exit of a MCP

Capillary optics is a basic X-ray technology capable to deliver a high flux density within a sub-micrometer spot. This compact optics could be easily used both to guide and to shape an intense X-ray beam within a small spot, a low divergence and with a high homogeneity. Arrays of curved tapered capillaries (polycapillary optics) can be used to focus, collimate, and filter x-ray radiation [1]. In addition to the established use of capillary optics to shape radiation in x-ray lithography, x-ray astronomy, crystal diffraction, x-ray fluorescence, neutron prompt gamma analysis, etc., the mode propagation of x rays in capillaries allows other unique applications, e.g., x-ray microscopy and focusing of coherent x-ray sources. We present here synchrotron radiation soft X-ray experiments performed in transmission with different values of curvature radius of thin Microchannel plates (MCPs), the optics formed by hollow micro capillaries [2]. MCPs, we characterized, are the arrays of 104-107 miniature hole microchannels oriented parallel to one another and characterized by spatial regular channels with hexagonal symmetry in the transverse cross-section. The channel matrix of MCPs is fabricated from silicon-lead glass and axes are normal to the MCP surface. In this study we measured both angular and energy distributions of X-ray radiation for two types of MCPs: one with diameter 3.4 µm, a pitch size of 4.2 µm and a thickness of ~0.27 mm and a second with a diameter of 10 μm and pitch size of 12 µm. The length to diameter ratio is about 80 for both. The Reflectometer, the end-station for XUV-Optics beamline recently made available at the BESSY synchrotron radiation facility, has a four circles goniometer: two for sample scans and two for the detector. A layout of this UHV-Reflectometer is showed in Ref. [3]. We measured the primary monochromatic radiation transmitted by MCPs, propagating through the microchannels of these devices. The monochromatic radiation travelling inside the microchannels of the MCP’s was detected by a pinhole photodiode with a circular window of 0.5 mm diameter, located at the distance of 310 mm from a sample, inside the Reflectometer. In particular, we have measured the soft X-ray transmission in the energy range around Si L and K edges (from ~100 to 1800 eV) to characterize the fine structures of angular distributions of the radiation at the exit of MCPs. We also calculated the transmission efficiency of MCPs (both flat and spherically-bent) at the fixed energy of the primary radiation (E=100, 450, 900, 1800 eV). Data at 1800 eV point out an efficiency of ~60% for the MCP with a microchannel diameter of 3.4 μm. Actually, the same value corresponds to the light transmission efficiency of a flat MCP. To focus a x-ray parallel beam a MCP device has to be bent with a spherical shape. We characterized a spherically-bent MCP with the radius of 50 mm and microchannel diameters of 10 µm. The spherical shape has been achieved by thermally bending these plates with a special metallic mandrel. Experimental data pointed out an optimal focus distance from the window of the detector to the surface of the spherical bended device of ~27.5 mm, roughly half of its spherical radius. According to these measurements the transmission efficiencies of a MCP at 100 eV ranges from 57% to 22% working with a slit from 100 μm to 1 mm, respectively. The transmission efficiencies of such spherically-bent MCPs are roughly the same also at 450, 900 and 1800 eV. References 1. C.A. MacDonald, Focusing polycapillary optics and their applications, X-Ray Optics Instrum. (2010) 867049 2. M.I. Mazuritskiy, S.B. Dabagov, A. Marcelli, A.M. Lerer and K. Dziedzic-Kocurek, J. Synchr. Rad. 23 (2016) 274-280 3. A.A. Sokolov, F. Eggenstein, A. Erko, et. al., An XUV Optics Beamline at BESSY II, Proc. SPIE Vol. 9206, 92060J-1, doi: 10.1117/12.2061778

Speaker: Augusto Marcelli (LNF)

Slides marcelli_ch2016.pdf

70 Characterization of Non-Gaussian beam profiles of polycapillary lenses

Polycapillary x-ray optics are a powerful tool to focus x-ray radiation in order to achieve small spot sizes of about ~10 µm. Especially the capability to focus radiation in a broad energy range (5-30 keV) shows polycapillary x-ray optics to be without an alternative for compact table-top EDXRF spectrometers. Since their invention in the early 1990s, a lot of developments were made and many characterization studies were carried out. A good qualitative and quantitative description of the beam profile is achieved in most cases by means of Gaussian intensity distribution functions. Severe deviations from this simple case can occur in the high energy regime of about ~20 keV, where photons can penetrate glass walls on straight paths creating a corona-like intensity distribution around the primary spot (‘halo-effect’). As a consequence, the radiation transmitted by the polycapillary optics consists of a focused and an unfocused part. In this work, the experimental characterization of the beam profile is carried out with a modified knife-edge method using thin pure element foils. Afterwards, a suitable Inverse Radon-transformation is performed to gain the 2D-Intensity distribution from the 1D-Integral line scans, which can then be used as a model function to calculate fluorescence intensities from small microstructures. Finally, a comparison between calculated and experimental intensities will be shown.

Speaker: Mr Marcel Bremekamp (Helmut Fischer GmbH Intitut fuer Elektronik und Messtechnik)

Slides bremekamp_ch2016.pdf

71 Simultaneous K-edge subtraction tomography for strontium tracer using parametric X-ray radiation

The X-ray source based on parametric X-ray radiation (PXR) has been regularly providing a coherent X-ray beam for application studies at Nihon University. Recently, three dimensional (3D) computed tomography (CT) is one of the most important applications of the PXR source. In particular, the methodology referred to as K-edge subtraction (KES) imaging is a typical application utilizing the energy selectivity of PXR. In order to demonstrate the applicability of PXR-KES, a simultaneous KES experiment for a sample containing strontium was performed using a PXR beam of the energy adjusted to the Sr K-edge 16.1keV. As the result, a 3D distribution of Sr was obtained from the subtraction between two tomographic images simultaneously acquired.

Speaker: Prof. Yasushi Hayakawa (Laboratory for Electron Beam Research and Application (LEBRA), Nihon University)

Slides hayakawa_ch2016.pdf

Lunch

S1.3: Channeling & Radiations in Crystals

Convener: Dr Robert CHEHAB (IPNL/IN2P3)

72 A review of transmission channeling experiments using focused MeV protons through thin crystals

This presentation will review work conducted at CIBA, at the National University of Singapore on MeV ion channeling analysis using a focused beam and the Interplay between ion optics and ion channeling to develop new modes of imaging, analysis and beam alignment. MeV ion channeling is well-established in using broad, unfocused beam in conjunction with analytical techniques such RBS to study crystal quality and lattice location. A nuclear microprobe brings additional flexibility to channeling studies in that it uses a system of quadrupole lenses for focus MeV beams to small spots on the wafer surface. Spots as small as 10 to 20 nm can be achieved. The focused beam can be displaced in position or angle using different modes of magnetic or electrostatic deflection. First, the focused beam can be scanned in position over the aligned wafer surface with the beam-crystal alignment preserved, allowing any form of crystal defect, such as dislocations, stacking faults, precipitates to be detected by the resultant localized dechanneling. Use of a transmission channeling through crystals which are thinned to around 20 microns allows one to detect the dechanneled beam fraction by its higher energy loss. Second, the focused beam can be deflected in angle around a fixed position on the wafer surface, allowing the beam-crystal alignment to be altered with high precision and angular images to be collected. In other work on proton beam deflection in a bent crystal lattice, graded epitaxial silicon-germanium layers wafers were grown on a silicon substrate. The off-normal lattice planes of the epilayer are gradually tilted, allowing beams to be steered. This process is now not limited by the cross-sectional surface area. Use of several such crystals in a volume reflection geometry allows charged particle beams which are distributed over large areas to be deflected using the multiple volume reflection effect. We have also recently developed a process to fabricate ultra-thin silicon (001) crystal membranes of a thickness of 55 nm with a very low surface roughness. These ultra-thin membranes allow the study of early stages of ion trajectories along axial channels with very high angular resolution owing to very low multiple scattering, so that any fine structure can be revealed. They have formed the basis of our recent high-resolution channeling measurements with MeV protons where an astonishing wealth of fine angular structure is revealed, such as within {111} planes where planar channeling within the narrow planes is resolved from that in the wider planes, channeling images comprising the superposition of difference axial potential wells and a study of the superfocusing effect.

Speaker: Prof. Mark Breese (National University of Singapore)

Slides breese_ch2016.pdf

73 X-Rays Monochromatic Radiation of the Bunch of Positrons Channeled in Nanotubes

The account of polarization of the nanotube medium imposes a limit on the energy of the bunch for the generation of channeling radiation of positrons. The larger the amplitude of the harmonic oscillation of the positron in nanotube, the greater the threshold value of the energy. When the energy of the bunch is equal to the upper threshold, all positrons of bunch contribute to the radiation. As a result, directional monochromatic and sufficiently intense radiations of soft X-ray photons are generated.

Speaker: Mr Koryun Gevorgyan (Yerevan State University)

Slides gevorgyan_ch2016.pdf

74 Diffracted transition radiation of a beam of relativistic electrons in a thin single-crystal plate

In the present work, diffracted transition radiation (DTR) of the beam of relativistic electron crossing a thin single-crystal plate. The expression for the DTR angular density has been derived for the case when the path of the electrons in the target considerably less than extinction length. For the first time the kinematic character of DTR of the beam of ultra-relativistic electrons crossing a thin single-crystal plate has been proved. The numerical calculation carried out shown a considerable influence of divergence of the beam on the angular density of DTR for high and super high energies of the electrons. The investigation has been carried out at the expense of grant of Russian Science Foundation (project №15-12-10019)

Speaker: Prof. Sergey Blazhevich (Belgorod State University)

Slides blazhevich_ch2016-1.pdf

75 Ratio of the contributions real and virtual photons diffraction in thin perfect crystals.

Yu. A. Goponov, S.A. Laktionova, M.A. Sidnin, I.E. Vnukov, Belgorod National Research University, 14 Studencheskaya str., 308007 Belgorod, Russia To evaluate the previously proposed method of calculating diffracted photon yields in thin perfect crystals [1], a comparison between calculated and experimental results [2-6] in the wide energy range of electrons and photons and the two implementing mechanisms of real photons emission generation: predominant contribution of the diffracted bremsstrahlung - experiments [2,3] and diffracted transition radiation – [4-6] was carried out. It is shown that the calculations according to the methodic [1] taking into account the experimental conditions describes the measurement results for thin crystals a rather well. Contribution of real photon diffraction is about 10-30% in the dependence from the crystal thickness. Experimental results for multi-crystal target in the experiment [6] where reported a significant excess of radiation yield in comparison with the calculation, taking into account the contribution of the diffraction of resonant transition radiation only, is analyzed. It is shown that the method [1] can’t explain the experiment result too. Possible contribution of both emission mechanisms: diffracted resonance transition radiation [6] and diffracted transition radiation [1] for the condition of the experiment [6] is discussed. The work is supported by the Ministry of Education and Science of the Russian Federation (the State assignment N 3.500.2014/K). References 1. S.A. Laktionova, O.O. Pligina, M.A. Sidnin, I.E. Vnukov // J. Phys. Conf. Ser. 517 (2014) 012020 2. D.I. Adeishvili et al. // DAN USSR, 1988, 298, P. 844. (in Russian) 3. A.V. Shchagin, V.I. Pristupa and N.A. Khizhnyak // NIM, 1995, B 99 P.277. 4. K.-H Brenzinger et al. //Z. Phys., 1997, A 358, P.107. 5. J. Freudenberger et al. // Phys. Rev. Let., 2000, 84, P.270 6. M.Yu. Andreyashkin et al. // JETP Lett., 1997, 65, P. 625

Speaker: Prof. Igor Vnukov (Belgorod sate university, Belgorod, Russia)

Slides vnukov_ch2016.pdf

76 Evolution of the Landau spectral peak produced by 50 GeV protons in Si detector with smoothly variable thickness

The ionization loss of relativistic protons moving in the depleted layer of Si detector is measured for different thicknesses of the depleted layer. The thickness of Si crystal of the detector was 300 µm, the thickness of the depleted layer was driven with applied high voltage from the detector power supply and was in the region 160–300 µm. The position and the width of the Landau spectral peak were measured as a dependence on the applied high voltage under normal orientation of the crystal to the proton beam axis. Additional measurements were performed for the maximal thickness of the depleted layer and different orientation angles of the crystal relative to the proton beam axis. The corresponding thicknesses of the depleted layer along the protons trajectory were in the range 300–1440 µm respectively to the orientation angles 0–78°. In both cases the evolution of the Landau spectral peak was observed. The experimental data are compared to results of calculations.

Speaker: Mr Ramazan Nazhmudinov (Belgorod National Research University)

Slides nazhmudinov_ch2016.pdf

77 SPONTANEOUS BREAKING OF SYMMETRY IN PROBLEM OF SPATIAL LOCALIZATION OF PARTICLE MOVING IN A SOLID

Early it was found the significant change in the size of the projectile’s wave packet correlation length during the initial short time after penetration in the volume of a solid. Because the correlation length becomes much less compared to the initial size of the packet, suppose that after the penetration in the solid the projectile appears in one of spatially localized states with the central mean point found in one of large number of positions predicted by the initial packet width. Such a spatially localized state can produce the polarization well that can capture the projectile in the same quantum-mechanical coupling state. In the present work the possibility of corresponding polarization phenomena are estimated and problems connected to this phenomenon are discussed.

Speaker: Dr Gennadiy Filippov (Cheboksary Polytechnic Institute)

Slides filippov_ch2016.pdf

78 PERSPECTIVE STUDY OF CHRMONIUM, EXOTICS AND BARYONS WITH CHARM AND STRANGENESS

The spectroscopy of charmonium-like states together with the spectroscopy of charmed and strange baryons is discussed. It is a good testing tool for the theories of strong interactions, including: QCD in both the perturbative and non-perturbative regimes, LQCD, potential models and phenomenological models [1, 2, 3]. An understanding of the baryon spectrum is one of the primary goals of non-perturbative QCD. In the nucleon sector, where most of the experimental information is available, the agreement with quark model predictions is astonishingly small, and the situation is even worse in the strange and charmed baryon sector. The experiments with antiproton-proton annihilation and proton-proton collisions are well suited for a comprehensive spectroscopy program, in particular, the spectroscopy of charmonuim-like states and flavour baryons. Charmed and strange baryons can be produced abundantly in both processes, and their properties can be studied in detail [1, 2, 3]. For this purpose an elaborated analysis of charmonium, charmed hybrid and tetraquark spectrum together with spectrum of charmed and strange baryons is given. The recent experimental data from different collaborations are analyzed. A special attention was given to the recently discovered XYZ-particles. The attempts of their possible interpretation are considered [4 - 7]. The results of physics simulation are obtained. Some of these states can be interpreted as higher-lying charmonium and tetraquarks with a hidden charm. It has been shown that charge/neutral tetraquarks must have their neutral/charged partners with mass values which differ by few MeV. This hypothesis coincides with that proposed by Maiani and Polosa [8]. Many heavy baryons with charm and strangeness are expected to exist. But much more data on different decay modes are needed before firmer conclusions can be made. These data can be derived directly from the experiments using a high quality antiproton beam with mo-mentum up to 15 GeV/c planned at FAIR and proton-proton collisions with momentum up to 26 GeV/c planned at NICA. References [1] W. Erni et al., arXiv:0903.3905v1 [hep-ex] (2009) 63. [2] N. Brambilla et al., European Physical Journal C 71:1534, (2011) 1. [3] J. Beringer et al., Review of Particle Physic, Physical. Review, D 86, (2012). [4] M.Yu. Barabanov, A.S. Vodopyanov, Physics of Particles and Nuclei Letters, V.8, N.10, (2011) 1069. [5] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen, Physics of Atomic Nuclei, V.77, N.1, (2014) 126. [6] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen , Physica Scripta, T 166 (2015) 014019. [7] M.Yu. Barabanov, A.S. Vodopyanov, S.L. Olsen, A.I. Zinchenko, Physics of Atomic Nuclei, V.79, N 1 (2016) 126. [8] L. Maiani, F. Piccinini, A.D. Polosa, V. Riquer, Phys. Rev. Lett. 99 (2007) 182003.

Speaker: Dr Mikhail Barabanov (Joint Institute for Nuclear Research)

Coffee break

S1.4: Channeling & Radiations in Crystals

Convener: Augusto Marcelli (LNF)

79 Coherent processes and channeling at high energy in thin crystals

At passing of charged high energy particles through crystal the phenomenon of channeling is possible, at which the particles move inside channels created by strings of crystal atoms or by crystal planes, by periodically deviating from the channel direction to small angles. In ultrathin crystals the phenomenon of channeling is absent, although there remains the possibility of manifestation of different coherent and interference effects at interaction of particles with crystal atoms [1]. In the present work some results are presented of the study of electromagnetic processes at high energies in the transitional region of thicknesses, between those at which the channeling is possible and those at which this phenomenon is absent. The quantum and classical theories of the scattering and radiation processes are presented, that are correct in the given range of crystal thicknesses, being based upon quasiclassical approximation of quantum electrodynamics and upon developing of numerical methods of analysis of the considered processes connected with operator and spectral methods of solution of wave equations [2-5]. The main attention is paid to the comparative analysis of quantum and classical characteristics of the processes of scattering and radiation as functions of crystal thickness and particle energy. References 1. A.I. Akhiezer, N.F. Shul’ga. High Energy Electrodynamics in Matter. Gordon & Breach, New York, 1996. 2. M.D. Feit, J.A. Fleck, A. Steiger. J. of Comp. Phys. 47 (1982) 412. 3. S.B. Dabagov, L.I. Ognev. NIM B30 (1988) 185. 4. A.V. Kozlov, N.F. Shul’ga, V.A. Cherkaskiy. Phys. Lett. A374 (2010) 4690. 5. N.F. Shul’ga, V.V. Syshchenko, A.I. Tarnovsky, A.Yu. Isupov. NIM B370 (2016) 1.

Speaker: Prof. Mykola Shul'ga (National Science Center "Kharkov Institute of Physics and Technology", 61108 Kharkov, Ukraine)

Slides shulga_ch2016-inv.pdf

80 Observation of independence of the nuclear de-channeling length on the particle charge sign

Under coherent interactions, particles undergo correlated collisions with the crystal lattice and their motion result in confinement in the fields of atomic planes, i.e. particle channeling. Other than coherently interacting with the lattice, particles also suffer incoherent interactions with individual nuclei and may leave their bounded motion, i.e., they de-channel. This latter is the main limiting factor for applications of coherent interactions in crystal-assisted particle steering. We experimentally investigated the nature of dechanneling of 120 GeV/c e− and e+ in a bent silicon crystal at H4-SPS external line at CERN. We found out that while channeling efficiency differs significantly for e− (4±2%) and e+ (53±2%), their nuclear dechanneling length is comparable, (0.7±0.1) mm for e− and (0.85±0.15) mm for e+. The experimental proof of the equality of the nuclear dechanneling length for positrons and electrons is interpreted in terms of similar dynamics undergone by the channeled particles in the field of nuclei no matter of their charge.

Speaker: Vincenzo Guidi (FE)

Slides guidi_ch2016.pdf

81 OPTIMIZATION OF AN HYBRID POSITRON SOURCE USING CHANNELING

The advantages of the hybrid positron source using channeling radiation, related to the yield, the converter heating and the Peak Energy Deposited Density (PEDD) in the converter , made it to be chosen as the baseline for CLIC. An optimization study concerning the positron converter –a granular target made of small tungsten spheres- has been worked out. The simulation results show that the energy deposition and the thermal shocks are considerably reduced. Applications to CLIC and ILC have been carried out. Tests have been performed in autumn 2015 at KEK. Both simulations and experimental results are reported.

Speaker: Dr Robert CHEHAB (LAL/IN2P3)

Slides chehab_ch2016.pdf

82 Textured polycrystal for increasing of positrons production

Now, positrons are produced in tungsten single-crystalline and amorphous targets, see, e.g., [1]. To regret, application of tungsten single-crystals is restricted because of a short dechanneling length of incident electrons. We propose to apply textured polycrystalline target for increasing of the positron production. The polycrystalline target can be produced as a set rolled tungsten foils and installed behind of a thin tungsten single-crystalline target. Application of textured polycrystalline target can increase the probability of the channeling of incident electrons and, hence, increase production of positrons. Channeling of electrons in textured (molybdenum) polycrystal recently has been observed in [2]. The research was supported by the Ministry of Education and Science of the Russian Federation, project 3.2009.2014/K. References [1]. X. Artru, I. Chaikovska, R. Chehab, M. Chevallier, O. Dadoun, K. Furukawa, H. Guler, T. Kamitani, F. Miyahara, M. Satoh, P. Sievers, T. Suwada, K. Umemori, A. Variola, Investigations on a hybrid positron source with a granular converter, NIM B 355 (2015) 60-64. [2] Y. Takabayashi, K. Ishiji, Observation of channeling effects for relativistic electrons in a polycrystal, NIM B 355 (2015) 53-56.

Speaker: Dr Alexander Shchagin (Kharkov Institute of Physics and Tecknology)

Slides shchagin_ch2016-1.ppt

83 Depth oscillations of electronuclear reactions caused by relativistic planar channelled electrons: quantum versus classical calculations

Depth oscillations of electronuclear reactions were observed in original experiment in [1]. The computer simulation of the depth oscillations effect of the electronuclear reactions yield was performed in [2] for 700 MeV electrons at <111> axial channelling in silicon crystal. In this work the oscillations effect is investigated for (220) planar channelled electrons in silicon crystal in the framework of quantum and classical theories using the modern computer code BCM-1.0 [3], which was successfully applied to explain recent experiments on relativistic electrons scattering in the crystals [4-5]. Within quantum approach the flux density was obtained using numerically calculated wave functions [6] of transverse states of channelled electrons. The convolution of the atomic thermal vibrations distribution function in the crystal with the flux density depending on the penetration depth is thus proportional to the electronuclear reaction yield. In the classical approach the flux density of electrons in a crystal is calculated using simulated trajectories of channeled electrons. Then this function also was convoluted with atomic thermal vibrations distribution function. Both approaches revealed the oscillations of the electronuclear reactions yield initiated by planar channeled electrons, depending on the beam energy and beam-crystal alignment. The comparison of quantum and classical calculations is performed. References 1. A.P. Antipenko, V.F. Boldyshev, V.I. Kasilov and other, DAN SSSR, 291 (1986) 589. 2. Yu.M. Filimonov, Yu.L. Pivovarov and S.A. Vorobiev, Nuclear Physics, 47 3 (1988) 894-895. 3. O.V. Bogdanov, E.I. Fiks, K.B. Korotchenko, Yu.L. Pivovarov and T.A. Tukhfatullin, Journal of Physics: Conference Series 236 (2010) art. No 012029. 4. Y. Takabayashi, Yu.L. Pivovarov, T.A. Tukhfatullin, Phys. Lett. A 378 (2014) 1520. 5. Y. Takabayashi, Yu.L. Pivovarov, T.A. Tukhfatullin, Phys. Lett. B 751 (2015) 453. 6. Yu.L. Eikhorn, K.B. Korotchenko, Yu.L. Pivovarov and T.A. Tukhfatullin, Journal of Physics: Conference Series, (2016), (in print)

Speaker: Mr Yuri Eykhorn (National Research Tomsk Polytechnic University)

84 The manifestation of the band structure in the photon emission spectrum of the fast above-barrier oriented particle

The calculation of the quasi-Bloch energy spectrum of the oriented fast charged particle entering the crystal at an angle substantially greater than the Lindhard angle is performed. It is shown that the band structure with the presence of allowed and forbidden bands completely preserved during the passage of fast charged particles high above the crystal potential. The processes of the photon generation by the quantum crystal-oriented particle entering into the crystal at an angle substantially greater than the Lindhard angle are considered. The probability of the photon excitation by the quantum above-barrier channeled particle is calculated. It is proved that all of the essential features of the above-barrier band structure manifest themselves as the components in the emission spectrum of the crystal-oriented fast charged particle.

Speaker: Dr Evgeny Mazur (NATIONAL RESEARCH NUCLEAR UNIVERSITY MEPHI)

Slides mazur_ch2016.pdf

PS2: Poster Session

Convener: Mr Luca Marchitto (Istituto Motori- Im)

85 About possibility of high energy electron beam parameters estimation by means of radiation from periodical structures

Yu. A. Goponov1, M.A. Sidnin1, K. Sumitani2, Y. Takabayashi2, I.E. Vnukov1 1) Belgorod National Research University, 14 Studencheskaya str., 308007 Belgorod, Russia 2) SAGA Light Source - 8-7 Yayoigaoka, Tosu, Saga 841-0005, Japan Recently, in connection with the design of the International Linear Collider [1] and Compact Linear International Collider [2] increased interest in new methods of determination of parameters of ultra-fast electrons beams (Ee >>10 GeV) with a transverse size of about several tens nm. Currently used methods of electron beams diagnostics based on the detection of radiation in the optical range stop working due to the coherent effects in radiation [3]. The transition to X-ray radiation with a shorter wavelength and oriented crystals [4] is hampered by the rapid degradation of the crystal structure due to the high density of particles on a target [5] and its destruction. The use of surface PXR [6] proposed in [5], is feasible only for Ee>200 GeV and greater because of small values of the radius of attenuation of the Coulomb field of the particle γλ, where γ is Lorentz-factor and λ is emission wavelength. Discussing the prospect of use for diagnostic purposes of radiation of electrons when they fly near the x-ray mirror, this will give the opportunity to work with a longer wavelength to obtain the desired values of γλ (about some hundred microns and greater) on already existing electron accelerators. Desirable X-ray mirror parameters and needful experimental equipment for proof-of-principle experiment at Mainz microtron and KEK-ATF accelerator are discussed. The work is supported by the Russian Science Foundation Grant (project N 15-12-10019). References 1. ILC Technical Design Report, 12 June 2013 // www.linearcollider.org/ILC/TDR 2. A Multi-TeV linear collider based on CLIC technology: CLIC Conceptual Design Report, edited by M. Aicheler et al. // CERN, 2012. 841 p. 3. H. Loos et al. // Proc. FEL’08, Gyeongju, Korea, August 2008. – THBAU01, – P. 485. 4. A. Gogolev et al. // J. Phys.: Conf. Ser. 357 (2011) 4. 5. Yu.A. Goponov et al. // NIM, 2016, A808, P. 71 6. A.I. Benediktovitch, I.D. Feranchuk // J. Phys. Conf. Ser. 236 (2010) 012015

Speaker: Prof. Igor Vnukov (Belgorod sate university, Belgorod, Russia)

86 Angular distribution of the radiation of an electron moving along the arc of a circle

The results of numerical analysis of angular distribution of the radiation of an electron moving on a plane along a circle arc are presented. The numerical values of global extremum of the sigma and pi-components of the linear polarization are determined. The analysis has shown that there are invariant directions where there is always the maximum (minimum) value of the radiation power.

Speaker: Prof. Vyacheslav Tlyachev (AdSU)

87 Angular Distributions and Spectra of VUV Radiation Generated by 5.7 MeV Electrons in Multilayer

Recently, in [1,2] radiation generated by the electron beam in a multilayer periodic structure was experimentally observed in the vacuum ultraviolet (VUV) range. The mechanism of this radiation is similar to the parametric X-ray radiation (PXR) of relativistic charged particles in crystals [3] This report presents the results of an experimental study of the angular distributions and spectra of VUV PXR generated by 5.7 MeV electrons in a Mo/Si multilayer structure. A series of angular distributions were measured for several values of grazing angle of electron beam incidence on the multilayer surface in the range of 30o-77o. The angular distributions were measured in the diffraction plane and at the angle qDy = 1/g with respect to this plane. The spectrum of PXR from multilayer target was tested by other multilayer mirror using the Bragg diffraction. The experimental results are compared with the simulation using the theory [4,5]. The present research was partially supported by the Ministry of Education and Science, the state order No. 3761, and by the Russian Foundation for Basic Research, the project No. 14-02-01032. References 1. S.R. Uglov, V.V. Kaplin, L.G. Sukhikh, A.V. Vukolov, JETP Letters Vol.100 No.8 (2014) 503. 2. S.R. Uglov, V.V. Kaplin, A.P. Potylitsyn, L.G. Sukhikh, A.V. Vukolov and G. Kube, Jour. of Phys.: Conf. Ser. 517 (2014) 012009. 3. Bazylev V.A., Zhevago N.K. Radiation of fast particles in matter and in external fields (Moscow: Nauka 1987). 4. N.N. Nasonov, V.V. Kaplin, S.R. Uglov, M.A. Piestrup, C.K. Gary, Phys. Rev. E 68 (2003) 036504. 5. A.S.Kubankin, V.Likhachev, N.Nasonov, A.Rakitjansky and P. Zhukova, Nucl. Instrum. and Meth. B 252 (2006) 124.

Speaker: Dr Alexander Kubankin (Belgorod National Research University)

88 Application of dielectric fibers for the electron beam diagnostic

The dielectric fibers are widely used in technique for light transport and as the beam loss position monitor in particle accelerators. This work reports the results of the experimental investigations of polarisation radiation properties in the dielectric fibers for different fiber positions relative to an electron beam. The experimental results show that we can use fibers for non-invasive beam position monitoring. Additional information associated from measuring the spectral characteristics of the field of electron bunches at any point cross-section are also presented and discussed.

Speakers: Dr Gennady Naumenko (Tomsk Polytechnic University), Mr Vitold Bleko (National Research Tomsk Polytechnic University)

89 Application of tungsten tips for neutron sources development

Pyroelectric crystal with a tungsten tip is a well-known setup used to accelerate ions for the D-D neutron generation [1,2]. The use of the tungsten tip enables to ionize residual gas in a local volume, generating ions for further acceleration. Such peculiarity allows developing a compact neutron source. The neutron flux produced by such generator is low but can be applied for different calibration purposes, for example, for neutrino and dark matter detectors [3]. We experimentally studied modified scheme when the high voltage is applied directly to the tip from external power supply while all other geometry is equal to the pyroelectric generator case. The experiments were performed in a vacuum environment with residual deuterium gas playing a role of an ion source for D+-D fusion. The yield of neutrons from a metallic target covered by deuterated polyethylene was observed for different values of applied high voltage. Ion and electron currents from the target and the X-rays appearing as a result of electrons interaction with surrounding matter were monitored as well. Preliminary results show that the scheme for the neutron generation can be realized starting from a level of applied high voltage of about 30 keV, in contrast to the typical neutron guns which need the high voltage level of about a 100 kV and above. The tested setup is promising for further development of the generator prototype. The research was supported by the grant from the Russian Science Foundation (project №16-19-10535) References 1. Naranjo B, Gimzewski J K and Putterman S 2005 Nature 434 1115. 2. Geuther J, Danon Y and Saglime F 2006 Phys. Rev. Lett. 96 054803. 3. A.S. Chepurnov, V.Y. Ionidi, O.O. Ivashchuk, A.S. Kubankin, A.N. Oleinik, A.V. Shchagin Journal of Physics: Conference Series 675 (2016) 032031.

Speaker: Mr Andrey Oleinik (Belgorod National Research University)

90 Charge-exchange radiation

In the charge-exchange accelerators, negatively charged accelerated ions loss their electrons in a thin charge-exchange target and become positively charged ions. In the present paper, radiation arising at charge-exchange of non-relativistic ions a thin transparent charge- exchange target is considered. The formula for spectral and angular distribution of the number of quanta emitted by the hydrogen ion that change its charge from -1 to +1 is obtained. It is shown that the distributions of charge-exchange radiation are independent of the target properties. This means that the nature of charge-exchange radiation is different from the transition radiation. The yield of the charge-exchange radiation exceeds one due to the transition radiation that is emitted by the ion with permanent charge with the same velocity. The research was supported by the Ministry of Education and Science of the Russian Federation, project 3.2009.2014/K.

Speaker: Dr Alexander Shchagin (Kharkov Institute of Physics and Tecknology)

91 Coherent radiation characteristics of microbunched electron bunch formed in the stack of the two plates

The radiation in stack of the two plates of the electron bunch, microbunched in SASE FEL process, was investigated. Frequency-angular distribution of the radiation consists of two factors: the bunch form-factor around the resonant frequency and the radiation distribution formed by the passage of a single electron through a stack of plates. The region of radiated frequencies l both above and below has lower and upper limits due to the medium polarization. The radiation coherence is not inhibited from a transverse form-factor if the resonance frequency is close to the lower limit frequency. Although the probability of transition radiation is small but due to the coherence effect its intensity can be of the order of SASE FEL intensity. Herewith the line width shrinks by several orders. Experimental study of the phenomenon will determine the value of modulation depth parameter of the bunch also.

Speaker: Mr Hayk Gevorgyan (Student)

92 Coherent transition radiation from a train of tilted “pancake-like” ultrashort electron bunches.

In the report we analyze a possibility to use for a diagnostics aims the process of coherent transition radiation (CTR) produced by a train of tilted ultrashort electron bunches. Measuring spectral-angular distributions of CTR produced by such a train it is possible to determine microbunch length, bunch tilting angle, separation between bunches and modulation depth.

Speaker: Prof. Alexander Potylitsyn (Tomsk Polytechnic University)

93 Coherent X-ray radiation generated by divergent beam of relativistic electrons in composite structure “amorphous layer - vacuum - single crystal”

The dynamic theory of coherent X-ray radiation generated by a beam of relativistic electrons in three-layer structure consisted of amorphous layer, vacuum (air) layer and a single crystal has been developed. The expressions for spectral-angular density of diffracted transition radiation (DTR), parametric X-ray radiation (PXR) and their interference term have been derived within the framework of two-wave approximation of dynamic theory of diffraction of X-ray in single-crystal. The derived expression for spectral-angular characteristics of DTR contain the summands defining the contributions of transition radiation (TR) from amorphous layer, TR from the front boundary of single-crystal layer and their interference term to spectral-angular density of DTR. The dependence of the characteristics of DTR in such a structure on the beam divergence has been studied. The considerable influence of the beam divergence on the interference of Transition radiation (TR) from amorphous layer and front boundary of the single -crystal layer has been shown. It has been shown also that a slight change in thicknesses of the layers do not lead to change of character of interference in a vicinity of Bragg frequency (to transition from constructive to destructive interference). The present work is supported by the Ministry of Education and Science of the Russian Federation (project of state task No 3.500.2014/K and state task No 2014/420).

Speaker: Prof. Anton Noskov (Belgorod State University)

94 Cooling of ultrarelativistic β and μ particles in laser channels

The process of charged particles channeling through potential channels formed by crossed laser beams is described using classical approach and covering the effect of charged particles radiative deceleration in such channels. The way to increase charged particle beam cooling efficiency is present.

Speaker: Dr Alexey Dik (LPI RAS, NRNU MEPhI)

95 Dielectric Concentrator for Cherenkov Radiation: Sensitivity and Field Near the Focus

Recently we have reported on specific form of dielectric target that effectively concentrates Cherenkov radiation from a point charge into a small vicinity of the focus point [1]. It was shown that for decimeter-sized target made from typical dielectric (e.g., Teflon) and terahertz radiation frequencies, the field in focus can be around two orders of magnitude larger compared to the field at the surface of the target. In this report, we discuss the sensitivity of this device with respect to the deviation of charge’s velocity from the designed velocity. We show that for terahertz frequencies and Teflon target the admissible perturbation in velocity is around hundredths of percent. With this deviation, we steel obtain the expressed peak of the intensity near the focus. Stronger deviation results in absence of concentration. We also discuss the influence of frequency dispersion of the material. We derive asymptotic expressions for the field near the focus and consider radiation from finite length bunches. [1] Galyamin S.N., Tyukhtin A.V. Phys. Rev. Lett. 2014. V. 113. P. 064802(1-5). Work is supported by the Grant of the President of Russian Federation (No. 6765.2015.2) and the Grants from Russian Foundation for Basic Research (No. 15-32-20985, 15-02-03913).

Speaker: Dr Sergey Galyamin (Saint Petersburg State University)

96 Dynamical diffraction of thermal neutrons under influence of temperature gradient

The diffraction of thermal neutrons on x-cut quartz crystal for the symmetric Laue geometry under the action of a temperature gradient perpendicular to the reflecting atomic planes (101 ̅1) was theoretically considered. The controllability of a neutron beam in space and time is analyzed and its parameters are estimated (relative maximum intensity, the angular and energy distribution of obtained beams etc.).

Speaker: Mr Artur Movsisyan (Institute of Applied Problems of Physics NAS RA, Yerevan, Armenia)

97 Effects of correlation in transition radiation of super-short electron bunches

Nowadays there is a tendency to use short bunches rather than long ones. The shorter electron bunch is, the shorter the pulse of generated radiation can be. Extremely short pulses of electromagnetic radiation are to be widely used in nanotechnology, medicine, biology. In this report we investigate effects of correlations between electrons in transition radiation as far as these effects remain outside the scope of research. We consider the intensity of transition radiation from a super-short bunch of electrons as a sum of three parts: incoherent, coherent and correlation. We derive the conditions when the correlations can affect upon the coherent radiation. Correlation function of particle density distribution is obtained with help of Debye–Hückel theory. Contribution of correlations to the form-factor is investigated. The condition linking Debye radius in electron bunches and length of the bunch is obtained. The obtained results can be of use in the projects SINBAD and FLUTE (which are currently under construction) with bunches having extremely small length (~1-10 fs). The contribution of correlations to the form-factor and intensity of TR are estimated numerically for the existing and future facilities; we argue that the effect of correlations can be detected with existing technics.

Speaker: Ms Darya Danilova (National Research Nuclear Univesity MEPhI)

98 GEANT4 Simulations of the Low Energy Neutron Beam Formation

By means of program GEANT4 the research of possibility obtaining low energy neutron beams was performed. To get the neutron flux 18 MeV external proton beam from cyclotron C18/18 is planned. As a source of neutron flux is planned proton induced reactions on 9Be target. The neutron yield dependence on the thickness of beryllium target was investigated. The problems of reducing the ratio of gamma and neutron yields by inserting a lead sheet after the target of beryllium have been studied. By GEANT4 modeling the optimal thickness of lead was determined. By GEANT4 simulation of beam shaping assembly, included reflector and moderator was considered.

Speaker: Mr Vaghan Ivanyan (YerPhI)

99 Parametric X-ray radiation from powders with different grain size

Parametric X-ray radiation (PXR) appears during coherent scattering of the charged particle Coulomb field on the atomic structures. PXR was studied theoretically and experimentally in different geometries, in a wide range of charged particles energies and different targets (crystalline, polycrystalline and multilayer mirrors). Nevertheless, the PXR form powders is one of sufficient lacuna for considered radiation. The presented study is devoted to the PXR research in powders with different grain size. The results were comparted with the diffraction of wideband X-rays (XRD) on the same targets. The PXR is observed under interaction of a 7 MeV electron beam with diamond powders with grain sizes in the ranges 60-70 µm, 6-7 µm and 200-300 nm. The PXR photons are detected with two spectrometry channels at observation angles 150° and 180° relative to the direction of incident electrons propagation. The primary X-ray beam was generated by an X-ray tube with tungsten anode and the XRD photons are detected at an observation angle of 150°. The PXR and XRD spectral peaks corresponding to the crystallographic planes (111) and (220) were detected for all the targets and their yields are compared relatively to the values of grain size. The obtained results demonstrate differences in diffraction processes of real and virtual photons. The possibility of PXR application for atomic structure diagnostics is discussed. The reported study was funded by RFBR according to the research project No. 16-32-00502 мол_а and Program of the Ministry of Education and Science of the Russian Federation for higher education establishments, Project No. 3.2009.2014/K.

Speaker: Mr Ramazan Nazhmudinov (Belgorod National Research University)

100 Polarization and Radiation Generated by Moving Charge in Dielectric Tube

At the present work we consider the problem of electromagnetic radiation generated in the uniform motion of a point charge along the dielectric tube, on a small distance from the axis. At the presence of a moving charge inside the tube will be excited as the own frequencies, and all the others. The problem is solved using Maxwell's equations for the vortex and potential fields. By eliminating one of the fields - magnetic or electric - we obtain the corresponding second-order equation for each of them. Since the equations for the magnetic field the problem with the current delocalization is absent, it is more prefer to calculate the component of magnetic field, and then expressing the components of the electric field through them.

Speakers: Dr Gennadiy Filippov (Cheboksary Polytechnic Institute), Ms Irina Lysova (Chuvash State Pedagogical University)

101 Prediction, Observation and Study of Long-Distant Undamped Thermal Waves Generated in Pulse Radiative Processes

In the work the prperties of long-distant undamped thеhermal waves generated in pulse radiative processes are studied.

Speaker: Prof. Vladimir Vysotskii (Kiev National Shevchenko Univ, Kiev, Ukraine)

102 Quantum expression for frequency of coherent radiation of charged particle moving through a periodic medium

Properties of Vavilov-Cherenkov radiation were obtained by Frank and Tamm in classic approach. Shortly after, Ginzburg described these properties in quantum approach. Later, expressions for frequencies of coherent bremsstrahlung and parametric X-ray radiation in periodic medium were obtained by Ter-Mikaelian in classic approach neglecting transverse components of pulses. In present paper, we derive the general expression for frequency of coherent radiation of charged particle moving through a periodic medium in quantum approach with account of the transverse components of pulses. Classic expressions for frequencies of coherent bremsstrahlung and parametric X-ray radiation are derived from the general expression. Quantum and classic expressions for radiation frequency are compared and analyzed. The research was supported by the Ministry of Education and Science of the Russian Federation, project 3.2009.2014/K.

Speaker: Dr Alexander Shchagin (Kharkov Institute of Physics and Tecknology)

103 Radiation of a Moving Charge at the Interface Between Vacuum and Chiral Isotropic Medium

We consider radiation produced by a point charge flying through the plane interface between vacuum and half-infinite isotropic chiral medium. For description of chiral medium, we use symmetrized material relations and Condon dispersion model [1]. We deal with charge motion from vacuum into medium and backwards. In the case where charge enters medium, we perform generalization of paper [2], where authors considered only slow charge motion case. We deduce analytical expressions for Fourier components of electromagnetic field for arbitrary charge velocity. Further, we pay the main attention to investigation of the far field in vacuum. Total field in vacuum is a sum of a field with polarization coinciding with that of self-field of a charge (co-polarization) and a field with polarization orthogonal to that of self-field of a charge (cross-polarization). These waves are coherent and result in total spherical wave with elliptical polarization, with the polarization coefficient being connected with chirality parameter of the medium. We present typical radiation patterns and ellipses of polarization. We also deal with the case where charge flies from medium into vacuum area. In our previous paper [3], we investigated Cherenkov radiation in infinite medium described by Condon model. In certain frequency ranges, Cherenkov radiation propagates at small angle with respect to charge trajectory. In the present report, we investigate penetration of this radiation into vacuum area. It should be noted, that the interest to radiation of moving charged particles in media with chiral properties is connected with relatively new and prospective method for diagnostics of biological objects which uses the Cherenkov radiation – Cherenkov luminescence imaging [4]. Chirality (also referred to as optical activity or gyrotropy) is typical for biological matter and is caused by mirrorless structure of molecules. Work is supported by the Grant of the Russian Foundation for Basic Research (No. 15-32-20985). [1] Condon E.U. // Rev. Mod. Phys. 1937. V. 9. P. 432. [2] Engheta N., Mickelson A.R. // IEEE Trans. Antennas Propag. 1982. V. 30. No. 6. P. 1213. [3] Spinelli A.E. et al. // Nucl. Instr. Meth. Phys. Res. A. 2011. V. 648. P. S310. [4] Galyamin S.N., Peshkov A.A., Tyukhtin A.V. // Phys. Rev. E. 2013. V. 88. P. 013206.

Speaker: Dr Sergey Galyamin (Saint Petersburg State University)

104 Shock wave induced MHz «glow» of atmosphere

The presented results of model numerical calculations indicate that at the ionization with a strong shock wave travelling at supersonic speed, the air must «glow» with low frequency electromagnetic radiation (1-2 MHz), just as the solar wind generates the aurora borealis as a result of interaction with the magnetic field of the Earth. The results of ground-based observations of the process of strong shock wave propagation are given in [1]. It was shown that the propagation of the strong shock wave is followed with (a) Very Low Frequency electromagnetic radiation (2-5 kHz, VLF) and (b) low frequency acoustic signal ( 1 kHz). An obvious explanation of these effects is given. The results of numerical calculations conducted in the present work show that at the propagation of strong shock wave in the atmosphere, both the VLF electromagnetic radiation (2-5 kHz) [1], and the low frequency one (1-2 MHz) must be generated. The latter radiation is due to the action of the magnetic field of Earth on the directed supersonic flow of air ionized by a shock wave. Reference 1. A.R. Aramyan, S.A. Aramyan, S.G. Bilen, L.Sh. Grigoryan, H.F. Khachatryan, Chin. Phys. Lett., Vol. 32, No. 3 (2015) 034101.

Speaker: Dr Artur Aramyan (IAPP NAS RA)

105 Simulation of X-rays passing through the capillary structure

This study provides insight into the performance of the capillary system, as well as getting a qualitative picture of X beam redistributions while passing through these structures that becomes important for definition of optimal parameters of capillary structures specially designed.

Speaker: Mr Aleksandr Baryshnikov (NRNU MEPhI)

106 Statistical fluctuations of radiation in quasi-Cherenkov generators

Shot noise, intrinsic to electron beams, is the cause of statistical fluctuations in radiation generated by quasi-Cherenkov generators operating in stationary and non-stationary regimes. Radiated power and instability time growth are the main output parameters characterizing the dynamics of electron beam interacting via the radiation field. Shot-noise related fluctuations of radiated power and instability time growth impose appreciable limitations on the possibility of coherent summation of electromagnetic oscillations from several quasi-Cherenkov generators operating in microwave and terahertz ranges [1,2]. The optimal conditions minimizing the spread of the main output parameters have been found for stationary and non-stationary regimes of quasi-Cherenkov generator operation. [1] S.V. Anishchenko and V.G. Baryshevsky, Nucl. Instrum. Methods B 355 (2015) 76. [2] S.V. Anishchenko and V.G. Baryshevsky, Tech. Phys. 61 (2016) 934.

Speaker: Mr Sergei Anishchenko (Research Institute for Nuclear Problems)

107 The Influence of Transition Radiation Upon Electron-Positron Pair Ionization Loss

The problem of ionization energy loss of high-energy electron-positron pair in thin layer of substance is considered. It is assumed that the thin layer is situated in vacuum in the direction of the pair motion on some distance from the substance in which the pair is created. It is shown that in this case the approximation of parallel electron and positron velocities, which is usually used for calculation of pair ionization loss in homogeneous boundless medium, may not be strictly valid and the existence of non-zero angle of pair divergence is taken into account. It is shown that transition radiation, generated during the pair emission from the substance, in which it is created, leads to manifestation of interference effects in pair ionization loss in thin layer on much larger distances (from the pair creation point) than in the case of ‘classical’ Chudakov effect in boundless medium [1]. Moreover, at sufficiently small angles of pair divergence such effects can be manifested for arbitrary distances between the layer and the substance. In this case with the increase of this distance the pair ionization loss does not reach the value of the sum of independent electron and positron losses but remains suppressed comparing to this value. The present work is the generalization of the problems about pairs ionization loss in thin films from [2-4], which have been considered under conditions when the influence of transition radiation or non-parallelism of electron and positron trajectories upon ionization loss were negligible. 1. A.E. Chudakov, Izv. Akad. Nauk SSSR 19 (1955) 589. 2. S.V. Trofymenko, N.F. Shul’ga, Phys. Lett. A 377 (2013) 2265. 3. N.F. Shul’ga, S.V. Trofymenko, Phys. Lett. A 378 (2014) 315. 4. S.V. Trofymenko, N.F. Shul’ga, Nucl. Instr. Methods B 355 (2015) 140.

Speaker: Dr Sergii Trofymenko (Kharkov Institute of Physics and Technology)

108 The optimal model of crystalline undulator with intervals

The undulator radiation theory of channeling positrons in the crystalline undulator (CU), which consists of a bent single crystals, separated by intervals, was developed. The calculation formula for the frequency distribution of the radiation formed in CU with intervals was received in [1]. It is shown that undulator radiation may be intensified by the presence of intervals. In this paper, an analytical formula was obtained for the frequency distribution of photons number taking account the polarization of medium. The characteristics of radiation were investigated. The optimum value of the intervals length between monocrystals, for which constructive interference factor has the maximum value, was defined. This result is important for increasing the efficiency of the free electron laser.

Speakers: Dr Anahit Shamamyan (A. I. Alikhanyan National Laboratory (Yerevan Physics Institute)), Prof. Lekdar Gevorgian (A. Alikhanyan National Laboratory (Yerevan Physics Intitute))

109 THz polarization radiation from electrons passing corrugated dielectrical tube under noncentral propagation

Generation of electromagnetic radiation in the frequency region of terahertz (THz) has attracted ever-growing attention owing to fundamental significance and interesting applications. In our previous work [1] we investigated source of THz radiation based on electrons moving through the channel with variable radius, where radiation arises due to Cherenkov (CR) and Smith-Purcell radiations (SPR). In this work electrons moved centrally. In experiment it is difficult to achieve such conditions, therefore it is of importance to construct the theory free of this assumption. In order to correct theoretical model, e.g. for experimental conditions of LUCX facility in KEK, Japan [2], it would be very useful to investigate radiation under noncentral propagation at some distance b from axis of corrugated channel. Theoretical model describing noncentral propagation is discussed. Radiation characteristics for noncentral case are compared with those for central electrons propagation. Limiting case of b much less than internal radius of channel are considered. Intensity dependences of SPR and CR peaks on distance b are investigated for different target parameters.

Speaker: Mr Alexsandr Ponomarenko (Russia)

110 Total Yield and Spectra of Positrons Produced by Channeling Radiation from 0.1 – 1.5 GeV Electrons

As is known, the channeling radiation (CR) of high-energy electrons in a crystalline target (radiator) and subsequent electron-positron pair production in downstream amorphous target (convertor), so called a “hybrid” solution [1, 2], is the effective positron source. The Mathematica™ code BCM-1 [3] developed by the authors enables calculating the trajectories and radiation spectra of electrons and positrons at channeling in crystals. This code combined with the approach sugested in [4] was used to perform the comparison of the positron yield in a thin amorphous W converter produced by bremsstrahlung, by axial 〈100〉 and planar (110) channeling radiation in a W crystal [5]. Here we investigate the dependence of total positron yield from incident electron beam energy. The hybrid scheme of positron source using the radiation from 0.1 – 1.5 GeV axially channeled electrons for the case of using W crystalline radiator and thick Si, Ge and W amorphous converters is considered. Computer simulation is carried out taking into account positron stopping in the convertor. References 1. R. Chehab et al. Physics Letters B 525 (2002) 41. 2. X. Artru, R. Chehab, M. Chevallier, V.M. Strakhovenko, A. Variola, A. Vivoli, Nucl. Instr. Meth. B 266 (2008) 3868. G.Alexander, J.Barley, Y.Batygin, et al. Phys. Rev. Lett. 100 (2008) P.210801. 3. O.V. Bogdanov, E.I. Fiks, K.B. Korotchenko, Yu.L. Pivovarov, T.A.Tukhfatullin, J. of Phys.: Conf. Ser. 236 (2010) 1; doi:10.1088/1742-6596/236/1/012029. 4. V.A. Dolgikh, Yu.P. Kunashenko, Yu.L. Pivovarov, Nucl. Instr. Meth. B 201 (2003) 253. 5. S. V. Abdrashitov, O. V. Bogdanov, S. B. Dabagov, Yu. L. Pivovarov, T. A. Tukhfatullin, Nucl. Instr. Meth. B 355 (2015) 65-68; DOI 10.1016/j.nimb.2015.03.091

Speaker: Mr Sergei Abdrashitov (National Research Tomsk Polytechnic University)

111 Transition Radiation of Multicharged Ions in a Thin Plate

The problem of the transition radiation of multicharged ions at the interface between two media and in a thin plate under the charge-exchange conditions has been solved. It has been shown that the processes of pickup (or loss) of electrons by accelerated multicharged ions at the interface between two media significantly increases the yield of transition radiation. To observe the effects associated with a change in the charge of ions in the medium, their velocity should not be much higher than the Bohr velocity. The existing technical possibilities allow such experiments. Our analysis shows that the processes of charge exchange of multicharged ions in the medium result in a significant increase in the yield of transition radiation [1]. This is physically due to the appearance of an additional contribution to the yield from radiation of electrons that are picked up or lost by the multicharged ion in the medium. According to the analysis, this contribution is similar to the contribution from instantaneously starting or stopping charges. Narrow maxima in backward X-ray radiation at angles close to π/2 (the total external reflection) can be used to create new directional broadband sources of X-ray radiation. The revealed features of angular distributions can be suitable for designing detectors of charge distributions of multicharged ions. References 1. V.S. Malyshevskн, G.V. Fomin, I.A. Ivanova.,JETP, 122 (2016) 209.

Speaker: Mr Vyacheslav Malyshevsky (Southern Federal University, 344090, Rostov-on-Don, Russia)

112 VFEL-based THz radiation sources with resonators formed by metallic wires

Volume FEL (VFEL) lasing in centimeter and millimeter wavelength ranges [1-5] is an encouraging demonstration of the potential for the development of similar sources in other ranges of electromagnetic spectrum. This paper considers THz generation by a relativistic electron beam in a VFEL whose slow-wave structure (resonator) consists of a rectangular waveguide with an array of periodically strained metallic wires. Previous studies [6] have shown that the intensity of spontaneous quasi-Cherenkov radiation in photonic crystals built from parallel metallic wires increases significantly when the wavelength becomes comparable with the wire radius (kR~1). This ensures that the efficiency of electron beam interaction with the slow-wave structure based on such photonic crystals might be substantially higher than that with conventional structures (corrugated waveguides, combs, etc.). When the typical diameter of the wire is about tens or hundreds of microns, the maximal radiated power corresponding to the condition kR~1 is achieved in the THz range. As a result, ultrashort (from a few to tens femtoseconds) electron bunches with energies up to tens--hundreds mega-electron volts, which are typical of the accelerators in currently used and constructed FELs, will enable one to obtain short THz pulses of GW power in the described structures. The frequency of thus generated radiation, due to Bragg diffraction, depends on the mutual orientation of the photonic crystal and the beam and can vary as the crystal is rotated. References [1] V.G. Baryshevsky, K.G. Batrakov, A.A. Gurinovich [et al], Nucl. Inst. and Meth. A, 483 (2002), 21--23. [2] V.G. Baryshevsky, K.G. Batrakov, N.A. Belous [et al], arXiv:physics/0409125 (2004). [3] V.G. Baryshevsky, N.A. Belous, A.A. Gurinovich [et al], Proc. of FEL 2006, BESSY, Berlin, Germany, 331--334 (TUPPH012). [4] V.G. Baryshevsky, K.G. Batrakov, V.A. Evdokimov [et al], Nucl. Inst. and Meth. B, 252 (2006), 86--91. [5] V.G. Baryshevsky, N.A. Belous, A.A. Gurinovich [et al], Proc. of FEL 2009, Liverpool, UK, 134--137 (MOPC49). [6] V.G. Baryshevsky and A.A. Gurinovich, Nucl. Inst. and Meth. B, 355 (2015), 69--75.

Speaker: Mr Evgeny Gurnevich (Research Institute for Nuclear Problems of Belarusian State University)

Wednesday, 28 September

S4.1: Charged Beams Shaping

Convener: Dr Walter Scandale (ROMA1)

113 Channeling of Electrons and Positrons at SLAC

Since 2013, several key experiments have been performed at SLAC investigating channeling of positrons and electrons in bent crystals, the latter in an energy range from 3 to 20 GeV, using the FACET and the ESTB beam facilities. Using a Ferrara-made bent Si (110) crystal these experiments have measured channeling parameters in a little-explored energy range and have investigated the quasi-channeling oscillations predicted by Sytov et al. Quantitative measurements provide data suitable to benchmark simulations and, e.g., design crystal-based beam collimation systems. Some effects, like the apparent independence of the dechanneling length on beam energy, are surprising and, while consistent with simulations, have so far been difficult to describe with a simple analytic model. More recently, the experiments have shifted towards studying the gamma-ray emission by high-energy electrons passing through crystals. The SLAC facilities are presently undergoing changes related to LCLS-II construction. I will end my presentation with an outline of the plans for the new facilities and the ramification for the crystal program.

Speaker: Dr H.-Ulrich (Uli) Wienands (Argonne National Laboratory)

Slides wienands_ch2016-inv.pdf

114 Study of crystal extraction of circulating beam from the U-70 at injection energy.

Yu.A. Chesnokov, A.G. Afonin, V.T. Baranov, G.I. Britvich, P.N. Chirkov, V.A. Maisheev, D.A.Savin, V.I. Terekhov Institute for High Energy Physics in National Research Centre Kurchatov Institute, 142281, Protvino, Moscow region, Russia Abstract: Phenomenon of deflection of charged particle beam due to channeling in a bent crystal is good investigated and successfully applied for extraction of beam in high-energy accelerators, at the energies of about 10 GeV and higher. However, a big practical interest presents the task of bending and extraction of charged particles with energies below 1 GeV, for example, production of ultrastable beams of low emittance for medical and biological applications. That’s why two novel crystal technique, namely: thin sequential straight crystal targets, and array of short bent crystal strips were investigated in this report as elements for extraction of beam from U-70 accelerator. Experimental results were obtained for extraction of 1.3 GeV protons and six-charged carbon ions with energy of 450 MeV/nuleon.

Speaker: Prof. Yury Chesnokov (IHEP)

Slides chesnokov_ch2016.pdf

115 Relaxation of axially confined 400 GeV/c protons to planar channeling in a bent crystal

As a charged particle beam is aligned with one of the main axes of a slightly bent crystal, most of the particles follows the crystal curvature due to multiple scattering with bent crystal axes. This effect is called stochastic deflection and occurs under some circumstances. Indeed, in the case of positively charged particles, a portion of the beam may relax from the axial confinement to planar channeling. The mechanism of such relaxation and its implications are investigated through experimental work at the extracted line H8 from CERN Super Proton Synchrotron [1]. Two bent crystals were selected for the purpose, the first to meet the condition for stochastic deflection, the second, with a smaller bending radius, not to meet it. The experimental results were critically compared to computer simulations, which numerical integrate the equation of motion of each beam particle in the field of continuum potential and also takes into account the contribution of incoherent scattering with the nuclei and the electrons of the crystal. We introduced a physical quantity, named relaxation length, which determines the characteristic length for relaxation from axial confinement to planar channeling in a bent crystal. We firmly individuated a necessary condition for the exploitation of axial confinement or its relaxation for particle beam manipulation in high-energy accelerators. We demonstrated that with a short bent crystal, aligned with one of its main axis to the beam direction, it is possible to realize either a total beam steerer or a beam splitter with adjustable intensity. In particular, in the latter case, a complete relaxation from axial confinement to planar channeling takes place, resulting in beam splitting into the two strongest skew planar channels.

Speaker: LAURA BANDIERA (FE)

Slides Bandiera-channeling2016-relaxation.pptx

116 New optics on the basis of bent single crystals.

Recent experiments in CERN and IHEP have demonstrated the simple method of focusing of hadron beams with the help of specially fabricated bent single crystals. In these experiments the parallel beam was transformed in the focusing one on a distance equal approximately to 1-2 meter from a crystal. In this report we discuss further development of focusing on the basis of bent crystals. We present the theoretical description of transformation of beam parameters from point into parallel and focusing from point to point and give shortly results of new IHEP focusing experiment. Besides, we propose to produce bent single crystals for gamma beam focusing.

Speaker: Dr Vladimir Maisheev (IHEP)

Slides maisheev_ch2016-1.pdf

117 Cold Nuclear Fusion Development

Chemical energy—oil and gas—will run out in the next 30–50 years. In addition to drying out our chemical energy sources, there is the so-called greenhouse effect, which imposes severe restrictions on the use of fuel. Nuclear reactors use uranium and thorium, and their reserves will last for no more than 100–200 years. Cold nuclear fusion in metals is possible due to the fact that the implantation of impurity atoms in a crystal leads to their excitation at p-levels in the crystalline niches of the conductor. Conduction electrons do not allow an unexcited atom of impurity to exist in conductive crystals. This prohibition is overcome with the excitation of an impurity atom at by 10 eV or more, that is essentially a chemical reaction. If two such atoms are placed in the same cell at a small distance in a crisscross configuration, the residual quantum vibration with a frequency of 1017 appears between the nuclei of these atoms. In the fraction of a second, the reduced Coulomb barrier is overcome; and the fusion of two deuterium atoms into a helium nucleus occurs. There are signs that the USA soon will deal with cold nuclear fusion phenomenon in the Defense Advanced Research Projects Agency (DARPA).

Speaker: edward tsyganov (cold fusion power int)

Slides tsyganov_ch2016.pdf

118 Polarized Fuel for Controlled Thermonuclear Fusion

The use of polarized nuclei as a fuel for thermonuclear fusion reactors was suggested more than 30 years ago and discussed in detail in a series of seminal papers [1-4]. For magnetic confinement as well as for inertial fusion the total cross section can be increased significantly. Especially for the dominant nuclear fusion reactions 2H + 3H →4He+n + 17.58 MeV and 2H +3He→4He+p + 18.34 MeV, an enhancement factor close to 1.5 is expected in the energy range below 100 keV. Furthermore, the use of polarized fuel allows one to control the ejectile trajectories, via an enhancement in the forward-backward cross section asymmetry due to polarization. This allows one to control the energy transfer from the plasma to the reactor wall or to concentrate the neutron flux to defined wall areas. Nevertheless, this idea was received with some skepticism by the relevant scientific community, due to some uncertainty in the physics of the process, the low efficiency in the production of polarized beams for injection into plasma and the apparent difficulty of preserving the ion polarization for a time long compared with nuclear burning time. But more recently, as a consequence of significant progress in the field of atomic beam sources and polarized targets, the interest in this matter has been refreshed for both inertially and magnetically confined plasmas. The possibility of implementing nuclear polarization in present and future fusion reactors is discussed in this paper, with special reference to the IGNITOR project, which is currently carried on by a Italian-Russian collaboration. In particular the interaction between polarized ions and magnetic fields, both static and RF, which are typically used in a Tokamak for plasma heating via ion cyclotron resonance (ICRH), is considered. References 1. Kulsrud R.M. et al., Phys. Rev. Letters 49, (1982) 1248. 2. Kulsrud R.M. et al., Nucl. Fus. 26, (1986) 1443 3. Cowley S.C. et al., Phys. Fluids 29 (2), (1986) 430. 4. Coppi B. et al., Phys. Fluids 29 (12), (1986) 4060.

Speaker: Sergio Bartalucci (LNF)

Slides bartalucci_ch2016.pdf

119 The Interaction of the Ion and X-ray Beams with Energies Less than 30 keV with Deuterated Crystal Structures

The Interaction of the Ion and X-ray Beams with Energies Less than 30 keV with Deuterated Crystal Structures A.V. Bagulya1, O. D. Dalkarov1, M. A. Negodaev1, A. S. Rusetskii1, V.I.Tsekhosh1, A.A. Bolotokov2 1 P. N. Lebedev Physical Institute of Russian Academy of Sciences (LPI), 119991 Moscow, Russia 2 Corporation " Radium", 125057, Moscow, Russia At the ion accelerator HELIS [1,2] at the LPI, the X-ray spectra from surface of deuterated crystal targets under ion beam irradiation were studied. Additional peaks were found in the X-ray fluorescence spectra. Their appearance cannot be associated with any known elements, and is probably caused by the channeling effect of the ion beam or the products of nuclear reactions in the crystal structure of the targets. The measurements of neutron- and charged particle fluxes from deuterated targets during irradiation by ion or X-ray beam with energies less than 30 keV, indicate a possible stimulation of nuclear reactions in the deuterated crystal structure under ion or X-ray beam irradiation. References 1. A.V. Bagulya, O.D. Dalkarov, M.A. Negodaev, A.S. Rusetskii, A.P. Chubenko, V.G. Ralchenko, A.P. Bolshakov, NIM B 355 (2015) 340-343 2. A.V. Bagulya, O. D. Dalkarov, M. A. Negodaev, A. S. Rusetskii, and A. P. Chubenko, Phys. Scr. 90 (2015) 074051 (5pp)

Speaker: Dr Mikhail Negodaev (P.N. Lebedev Physical Institute of the Russian Academy of Sciences)

Slides negodaev_ch2016.pdf

11:00 Coffee break

S4.2: Charged Beams Shaping

Convener: Gianluca Cavoto (ROMA1)

120 Observation of channeling for 6500 GeV/c protons in the crystal assisted collimation setup for LHC

Two high-accuracy goniometers equipped with two bent silicon crystals were installed in the betatron cleaning insertion of the CERN Large Hadron Collider (LHC) during its long shutdown. First beam tests were recently performed at the LHC with 450 GeV/c and 6500 GeV/c stored proton beams to investigate the feasibility of beam halo collimation assisted by bent crystals. For the first time channeling of 6500 GeV/c protons was observed in a particle accelerator. A strong reduction of beam losses due to nuclear inelastic interactions in the aligned crystal in comparison with its amorphous orientation was detected. The loss reduction value was about 24. Thus, the results show that deflection of particles by a bent crystal due to channeling is effective for this record particle energy. The experimental results reported were obtained in the frame of UA9 experiment in CERN.

Speaker: Dr Walter Scandale (ROMA1)

Slides scandale-taratin_ch2016-inv.pdf

121 Crystal assisted extraction of proton beam from the new FCC injector synchrotron installed within the SPS tunnel

We explore an idea of the use of new superconducting synchrotron placed in the SPS tunnel as the FCC proton injector. The maximum output proton energy will depend on available dipole magnets and can be estimated in the range (1.5 − 3.5) TeV with dipoles from 7 T to 16 T, respectively. The extraction scheme is based on the usage of bent crystal deflectors that could provide beam extraction efficiency up to 90%. We also discuss some modifications of the synchrotron lattice that are necessary for installation of the extraction system elements.

Speaker: Prof. Alexander Kovalenko (Joint Institute for Nuclear Research)

Slides scandale-taratin_ch2016-inv.pdf

122 Bent crystals for beam extraction from the LHC

One of the goals of the CRYSBEAM project is to perform a feasibility study of design and manufacturing of bent crystals with a geometry optimised for extraction of the proton or the lead ions beams circulating in the LHC. In the frame of the UA9 experiment, aiming at collimation of the LHC circulating beam by means of channeling in bent crystals, steering of a 6.5 TeV proton beam at an angle of a few tens of microradians have been recently observed. Differently from the case of beam collimation, extraction demands a considerably larger deflection angle. Delivery of a high extraction efficiency demands a crystal bent at a radius of the order of 100 m and the absence of dislocations in the crystal region exposed to the beam. Requirement on the bending radius, together with the need of a deflection angle in the order of a few mrad, imposes manufacturing of a uniformly bent crystal with unconventional thickness, i.e. in the order of tens of centimeters. As a result, important technological developments in crystals bending and characterizations technique are required.

Speaker: Andrea Mazzolari (FE)

Slides mazzolari_ch2016.pdf

123 Measurements of multiple scattering of high energy protons in bent silicon crystals

The ordered positions of atoms in crystals give a reason to study multiple scattering of high energy charged particles within them. In addition, the accurate representation of multiple scattering of high-energy protons in a bent crystal is important for studies of crystal assisted collimation at the SPS and the LHC. Multiple scattering of 400 GeV/c protons in bent silicon crystals was measured for orientations far from the directions of main crystallographic planes and axes in conditions excluding channeling of protons. The observed RMS deflections are a little larger than those obtained from the Moliere theory. Simulation of multiple scattering in a model of binary collisions with the crystal atoms shows about 3.5% decrease of the RMS deflection with respect to the model of a sequence of random collisions. This is a possible indication on a reduction of multiple scattering of protons in a crystal in comparison with its amorphous state. The experimental results reported were obtained in the frame of UA9 experiment in CERN.

Speaker: Dr Alexander Taratin (Joint Institute for Nuclear Research)

Slides taratin_ch2016.pdf

124 Steering efficiency and dechanneling of a Sub-GeV Electron Beam as a Function of Curvature and Energy

We report the observation of efficient steering of sub GeV electrons at MAMI (MAinzer MIkrotron) facilities by means of planar channeling and volume reflection in a bent silicon crystal. A 15 μm thick plate of (211) oriented Si was bent to cause quasi-mosaic deformation of the (111) crystallographic planes, which were used for coherent interaction with the electron beam. The plate bending was obtained thanks to a remotely controlled device that allows for a fine tuning of the bending and the torsion by means of piezo-step motors. Remote adjustment of the bending allowed to record data in a wide range of deflection angles from 0.3 up to 1.5 mrad. Moreover the device guarantee a soft bending procedure “stitching before bending” making possible to manage fragile thin slabs bringing them to impressive curvature (about 3mm primary curvature was reached), close to the breaking limit of the material. The data allow studying the deflection efficiency and dechaneling-rechanneling phenomena as a function of the curvature. Moreover at the higher curvature data was collected in the energy range between 195 and 855 MeV. These results allow a deep understanding of the dynamics of electrons subject to coherent interactions in a bent silicon crystal in the sub-GeV energy range, which is relevant for realization of innovative x-ray sources based on channeling in periodically bent crystals.

Speaker: Dr Davide De Salvador (Padova University & INFN-LNL)

Slides DeSalvador_ch2016.pdf

125 State-of-the-art bent silicon crystals for high-energy charged particle beam collimation

Techniques used at the Sensor and Semiconductor Laboratory of Ferrara for producing strip crystals exploiting anticlastic curvature were recently enhanced by introducing the Magnetorheological Finishing to obtain crystals with ultraflat surface and miscut very close to zero. New materials were employed to realize the holders to fulfill compatibility constraints with the ultra-high vacuum of the LHC pipe. Characterization methods were also improved introducing a high resolution X-rays diffractometer coupled with a custom made autocollimator, and a new infrared light interferometer. One of the realized crystals allowed to observe channeling for the first time with 6.5 TeV proton beam in the LHC.

Speakers: Dr Andrea Mazzolari (FE), Dr Giacomo Germogli (FE)

Slides germogli_ch2016.pdf

Thursday, 29 September

W1.1: Mini-workshop “Simulation Techniques for Particle Dynamics in Ordered Structures

Convener: Vincenzo Guidi (FE)

126 Simulation of Channeling and Radiation of Ultra-Relativistic Projectiles in Linear, Bent and Periodically Bent Crystals by Means of MBN Explorer

The multi-purpose computer package MBN (Meso-Bio-Nano) Explorer that is being developed by MBN Research Center allows modeling of molecular systems of varied level of complexity with the sizes ranging from the atomic to the mesoscopic scales. It is suited to optimize the structure of a system as well as to run MD simulations. In specific application to the channeling phenomenon, the package allows one to modelling various crystalline structures, both straight and bent, to perform analysis of periodic bending in superlattices, to simulate the structure modification due to the surface deformations. The channeling module of the package provides efficient and reliable simulations of channeling of ultra-relativistic projectiles and for calculation of spectral and angular distributions of the emitted radiation. The predictive power of this software resides at the level of accuracy comparable or even higher than in current experiments. In the talk we will review the general and unique features of the computer package as well as report on the results obtained by means of the MBN Explorer during the last years in the field of channeling. The efficient algorithms of particle trajectories simulation implemented in MBN Explorer has allowed us to describe planar and axial channeling and radiation processes for different type of charged particles and crystals (of different kind and shape) occurring at different energies and at various crystal thicknesses including macroscopic (up to the cm range). In these simulations we have analyzed the particle dechanneling lengths, spectral and angular distributions of radiation emitted in the straight, bent and periodically bent crystals. These simulations elucidate all the elementary events of particle propagation through the crystal that contribute to the overall beam propagation and radiation effects. Many of these results are highly relevant in connection with the ongoing and planned experiments concerning the investigation of the properties of Crystalline Undulators.

Speaker: Prof. Andrey Solov'yov (MBN Research Center)

127 A method for calculation of emitted radiation in straight and bent crystals based on the Baier Katkov quasiclassical formula

An algorithm for the numerical calculation of the radiation spectrum based on the direct integration of the Baier Katkov (BK) formula is introduced. Since the coherent effects in the process of radiation emission in crystals appear when the angle between particle trajectories and crystal planes or axes is small and at ultra-relativistic energies the radiation angle 1/gamma is much smaller than unity, we can simplify the BK formula for radiated energy by using the small-angle approximation. The basis of the algorithm is to start from a classical trajectory. The electron/positron trajectory can be build with any of the Monte Carlo code available based on the integration of particle trajectories under the continuum potential approximation, thus solving the classical equation of motion through numerical integration. In principle, the BK formula should be integrated along the whole particle trajectory. Nevertheless, at very-high energy it may happen that the total probability of radiation exceeds unity, which means that multiple photon emission may occur. With the aim of simulating multiple photon emission, the classical trajectory can be divided into some intermediate-lengths, in a similar way as implemented by Artru [1], who was the first that treated both multiple coherent and incoherent radiation. Such algorithm has already been implemented in two different software [2,3], which generate the classical trajectories also taking into account the contribution of incoherent scattering with nuclei and electrons. In both cases, the presented method demonstrated its capability in predicting the experimental spectra of radiation in bent crystals for different beam energies, from sub-GeV [3,4] to hundreds of GeV [2,5]. Such algorithm can be easily adapted to other Monte Carlo softwares to predict the radiation generated by ultrarelativistic electrons/positrons in crystalline structures.

Speaker: LAURA BANDIERA (FE)

Slides bandiera_ch2016.pdf

128 BCM-2.0 – the New Version of Computer Code “Basic Channelling with Mathematica©”

“Basic Channelling with Mathematica©” BCM–1.0 is the computer code developed by the authors for solving numerous problems related to channelling [1]. The first version of the computer code allowed solving equation of motion of channelled relativistic particles in periodic electrical field of axis and planes both in the classical and quantum approach. Several software packages also have been developed recently for numerical simulations of the channeling process [2–4], but using another programming environments. Here we present a new version of computer code BCM–2.0 which is continuation and development of BCM–1.0. Newly developed different packages of this code were successfully applied to following problems: • Flux dynamics and angular distributions of relativistic electrons and positrons passing through the thin and half-wave crystals, including mirroring • Quantum resonances in reflection of relativistic electrons and positrons by a crystallographic surface • Cherenkov radiation from relativistic electrons in a crystal • Calculation of Cherenkov radiation angular distributions from channeled relativistic electrons (positrons) and heavy ions • Optical radiation from channeled relativistic heavy ions in vicinity of the Cherenkov angle • Asymmetry of the angular distribution of radiation of channeled relativistic electrons in optically transparent crystals • Angular distribution features of Channeling radiation in the optical range • PXRC (parametric X-Radiation at channeling) and its quantum features • Radiation energy loss of channeled relativistic electrons in a crystal • Channeling radiation from electrons in a half-wave crystal • Positron source via electron-positron pair production by channeling radiation • Orbital angular momentum of channeling radiation from relativistic electrons References 1. O.V. Bogdanov, E.I. Fiks, K.B. Korotchenko, Yu.L. Pivovarov T.A. Tukhfatullin, J. Phys.: Conf. Ser. 236 (2010) Article number 012029. 2. G.B. Sushko, V.G. Bezchastnov, I.A. Solovyov, A.V. Korol, W. Greiner, A.V. Solovyov, J. Comput. Phys. 252 (2013) 404. 3. A. I. Sytov, V.V. Tikhomirov, (2014) arXiv: 1412.0110. 4. E. Bagli, M. Asai, D. Brandt, A. Dotti, V. Guidi, D. H. Wright, Eur. Phys. J. C (2014) 74:2996 DOI 10.1140/epjc/s10052-014-2996-y

Speaker: Dr Timur Tukhfatullin (National Research Tomsk Polytechnic University)

Slides tukhfatullin_ch2016-2.pdf

129 Influence of space charge effect on dynamics of charged particles trapped in laser channels

Charged particles channeling in laser channels could be used for particle beams cooling, steering and shaping and has some benefits comparing to e.g. crystal channeling. As charged particle beams become more intense, influence of space charge effect on their dynamics is increasing and needs to be taken into account. To examine this phenomena numerically a simulation code taking into account particle-particle interaction was created. Results of its verification and application for simulation of dynamics of charged particles trapped in laser channel will be presented.

Speaker: Mr Evgenii Frolov (LPI RAS)

Slides frolov_ch2016.pdf

130 Electromagnetic Simulations of a Metamaterial Target for Applications in Particle Accelerators

Modern and future accelerators, such as linear colliders and X-ray Free Electron Lasers (X-FELs), will be capable of producing femtosecond and sub-femtosecond electron bunches with unprecedented intensity. Current techniques, such as the transverse deflecting cavity, have a resolution of approximately 1.3fs, but the beam is destroyed during the measurement process. A new non-destructive method, which employs a Left Handed Metamaterial (LHM) is promising as it provides additional flexibility in the generation and manipulation of radiation. In this report, we shall present our experimental plan, initial simulations and an overview of the infrastructure available to manufacture and verify the metamaterial’s properties.

Speaker: Mr Tom Vaughan (Royal Holloway, University of London)

Slides vaughan_ch2016.pdf

131 Modeling of channeling of deuterons in titanium deuteride

The channeling phenomena were modeled using the supplementary Geant4 library TPT-EM. It the model the incident deuterons were captured it the crystallographic channel by Ti-plane potentials. The height of the plane potential has been calculated according to the Linchard theory. The experimental effect of the 20 percent neutron yield enhancement in the energy range 7-12 keV was fit by the model with Xi2/ns = 0.83. In future we plan to develop a special TPT-EM multiple scattering process for low energy ions, which takes into account modification of projectile flux in the crystallographic channel.

Speaker: Mr Dmitry Sorokin (VNIIA)

Slides sorokin_ch2016.pdf

132 Geant4 simulations of the full-size calorimeter for muon G-2 experiment

The aim of this report is to investigate the full size electromagnetic calorimeter for the muon G-2 experiment at Fermilab. A calorimeter module (24 are expected in the experiment) consists of a Delrin front panel for installation of the laser calibration system, 54 PbF2 Cherenkov crystals wrapped by the black Millipore paper, and silicon photo-multiplier sensors. We report here on simulation of 2.0 GeV positrons passage through the calorimeter system. The simulations are carried out by using Geant4 toolkit, which provides a complete set of tools for all areas of detector simulation: geometry, tracking, detector response, run, event and track management, and visualization. We consider Cherenkov photons expansion when a positron moves down through the calorimeter at the arbitrary angles of incidence. Both spectral and angular distributions of Cherenkov optical photons in different parts of the calorimeter system have been evaluated as well as the pre-shower distributions in the panel and at the Al vacuum chamber of the storage ring.

Speaker: Mr Aleksandr Savchenko (NRNU MEPhI, Russia, Moscow)

Slides savchenko_ch2016.pdf

11:00 Coffee break

W1.2: Mini-workshop “Simulation Techniques for Particle Dynamics in Ordered Structures

Convener: Prof. Mark Breese (National University of Singapore)

133 The GECO project

A fundamental aspect of a successful physics experiment is the availability of a reliable and precise simulation code. In particular, Geant4 has seen a large expansion of its user community in recent years. Currently, the toolkit does not allow the simulation of particles interacting with other than amorphous states of matter. The GECO project is devoted to the development a general framework for the management of solid-state structures in the Geant4 kernel and to validate it against experimental data. The development of a Geant4 extension for the handling of crystal structures would allow the simulation of the mutual influence of various physics fields, and the exploration of novel applied physical effects. The enhanced Monte Carlo code will permit the combination of solid-state and nuclear effects for the study of nuclear interaction rate in crystals.

Speaker: Enrico Bagli (FE)

Slides bagli_ch2016-inv.pdf

134 Ab-initio Monte Carlo simulations of relativistic particle scattering and radiation in oriented crystals

Relativistic particle interaction with oriented crystals combines both classical and quantum features. Coherent particle scattering is described by the average (Lindhard) potential of planes and strings while quantum treatment is necessary to describe the incoherent scattering by both electrons and atomic cores. The latter has to be separated into large-angle single and small-angle multiple scattering with taking into consideration their suppression by collision correlations. Both classical and quantum features can be naturally combined using Monte Carlo method we have been developing for thirty years. The effect of electron rechanneling, multiple volume reflection in one crystal, crystal surface miscut influence on the high energy beam collimation process, channeling efficiency increase by crustal cut or buried amorphous layer, both planar channeling and quasichanneling oscillations in the deflection angle distribution in agreement with a number of experiments. The particle motion simulation method has been supplemented by the radiation and pair production simulation by the Baier-Katkov semi-classical method and successfully applied to simulate the e± synchrotron-like radiation, accompanying radiative cooling, self- polarization and anomalous magnetic moment modification, the e- radiation under the multiple volume reflection in one crystal, synchrotron-like e+e- pair production and accompanying dichroism, birefringence, transversely polarized e± production, e+ circular radiation in straight and bent crystals, e± radiation in crystal undulators. Though many groups have recently adopted the single scattering process, to make the correct simulation of the incoherent scattering more available, we have started to systematically implement this and other essential features into the CRYSTAL code. The algorithms of the latter possess high functionality providing a possibility of varying of initial parameters for optimization problem as well as plenty of different crystal axes and planes for different elements. Additionally, our simulation codes were adopted for high performance calculation using MPI at a multi-core machine and applied at CINECA supercomputers Fermi, Galileo and Marconi. We acknowledge the CINECA award under the ISCRA initiative for the availability of high performance computing resources and support.

Speaker: Alexei Sytov (FE)

Slides sytov_ch2016.pdf

135 Channeling of protons in radially compressed chiral carbon nanotubes

Channeling of 10 MeV protons in radially compressed chiral carbon nanotubes is considered. Monte Carlo simulation program is used for the calculation of the trajectories, energy losses and angular distributions of protons in nanotubes of various lengths and compression, where the potential in Doyle-Turner approximation is used to describe the interaction between a proton and a nanotube. Carbon nanotubes, which are considered, are radially compressed at different points with variable compression. The role of compression in different types of carbon nanotubes is investigated and the results show how it affects angular and energy distribution.

Speaker: Dr Stylianos Sarros (Researcher)

Slides sarros_ch2016.pdf

136 The X-ray characteristic line in the framework of the Boltzmann transport equation

The emission of characteristic lines after x-ray excitation is usually explained as the consequence of two independent and consecutive physical processes: the photoelectric ionization produced by the incoming photons and the successive spontaneous atomic relaxation. However, this is not the only mechanism for the formation of the characteristic lines. In first place, the photoelectric effect is not the only ionization mechanism driven by the incoming photons. As it has been recently shown, Compton ionization is another possible process which contributes not negligibly to the ionization of the shells L and M. In second place, secondary electrons from these two interactions, photoelectric and Compton, are also able to ionize the atom by means of the so called impact ionization. This contribution has been recently described showing that it can be more relevant at monochromatic energies which are specific of certain lines and elements. A third mechanism of line modification is the so called self-enhancement produced by absorption of the tail of the Lorentzian distribution of the characteristic line. These four effects concur to the formation of the characteristic line and must be considered to obtain a precise picture in terms of the shell and the element. This article furnishes a review of these contributions and their formal theoretical descriptions. It is given a complete picture of the photon kernel describing the emission of characteristic x-rays comprising the major photoelectric contribution and the three effects of lower extent. The line formed with all these contributions can then be followed along successive photon interactions in deterministic or Monte Carlo photon codes to describe better the multiple scattering effects.

Speaker: Prof. Jorge Eduardo Fernandez (Alma Mater Studiorum University of Bologna)

Slides fernandez_ch2016.pdf

137 Quantitative measurements of fuel spatial densities from GDI sprays through optical and x-ray based techniques

This paper reports the results of an experimental investigation to characterize the inner structure of a high-pressure gasoline spray injected by a 6-hole nozzle for Direct Injection Spark Ignition (DISI) engines. A desktop facility based on polycapillary optics system, providing a high flux beam with low divergence has been used. Both x-ray µ-tomography and radiography techniques have been applied in the region just downstream of the nozzle to get quantitative information about the local mass distribution and fuel flow. Conventional optical techniques can generally provide data only at larger distance from the nozzle due to multiscattering phenomena linked to the high spray density. This paper aims in comparing the results of x-ray based techniques with conventional non intrusive-diagnostics. The local mass distribution of a single jet at different distances from the nozzle was estimated through x-ray tomography and radiography. The single-jet fuel mass-rate was obtained and compared with the injection rate one measured by the injection Gauge Rate System working on the Bosch tube principle. The comparison demonstrates the accuracy of x-ray tomography desktop facility as a reliable diagnostic tool.

Speaker: Luca Marchitto (Istituto Motori- IM)

Slides marchitto_ch2016.pdf

138 A collimation system for ELI-NP Gamma Beam System – design and simulation of performance

ELI-NP is one of the three pillars of ELI (Extreme Light Infrastructures) European Project, to be built in Bucharest, Romania. This facility will host the Gamma Beam System (GBS), an intense and monochromatic gamma beam source based on inverse Compton interaction between a high-power laser and an accelerated electron beam produced by a warm linac. The EuroGammaS association, composed by many European research institutes and companies, guided by INFN, will provide the design, manufacturing, installation and commissioning of the GBS [1]. The gamma beam produced, with energy ranging from 0.2 to 20 MeV, an energy bandwidth 0.5% and a flux of about 10^8 photons/s, will be devoted to the investigation a broad range of applications, from nuclear physics and astrophysics, to material science and life sciences. As a result of the inverse Compton interaction, the radiation emitted is not intrinsically monochromatic. Infact, the energy is related to the emission angle, it is maximum in the backscattering direction and decreases as the angle increase [2-3]. Therefore, the required energy bandwidth can be obtained only by developing specific methods of collimation of the gamma beam, i.e. filtering out the radiation emitted at larger angles. The angular acceptance of the collimation, needed to obtain the required bandwidth, must be continuously adjustable in a range from few hundreds of micro-radians to 40 micro-radians, to operate in the entire energy range. The solution identified is a stack of linear slits, each with an adjustable aperture, arranged with a relative rotation around the beam axis to obtain, as result of the overlapping, an hole with an approximately circular shape. In this contribution, which represents an advance of the previous preliminary work [4], the final collimation design is presented. The layout of the slits and the materials selected to satisfy the requirements on the gamma-beam bandwidth have been identified by carrying out a series of detailed Geant4 simulations both of the high-energy and the low-energy beamline. In particular, the simulations concerned the transport of the gamma-beam produced at the Interaction Point (IP) to the collimation system along the vacuum pipes and chambers and relative shielding. The background radiation and the dose level in sensible areas of the experimental room (e.g. at the position of detectors and instrumentation racks) have been evaluated. Furthermore, an evaluation of the effects of misalignments and mechanical tolerances has been also performed. References [1] O. Adriani, et al. Technical Design Report EuroGammaS proposal for the ELI-NP Gamma beam System arXiv:1407.3669 [physics.acc-ph] (2014) [2] Vaccarezza, C. et al. A european proposal for the compton gamma-ray source of eli-np IPAC 2012 - International Particle Accelerator Conference 2012, pp. 1086-1088 (2012) [3] Petrillo, V. et al. Photon flux and spectrum of γ-rays Compton sources Nuc Instrum Meth A, 693, pp. 109-116 (2015) [4] Cardarelli, P. et al. Monte Carlo simulation of a collimation system for low-energy beamline of ELI-NP Gamma Beam System Nuc Instrum Meth B, 355 (2015)

Speakers: Dr Gianfranco Paternò (FE), Paolo Cardarelli (FE)

Slides paterno_ch2016.pdf

13:05 Lunch

S5.1: Novel sources: FEL/Laser/Plasma channels

Convener: Luca Serafini (MI)

139 Advanced topics in the physics of Compton back-scattering

Compton back-scattering has been demonstrated to provide compact, highly tunable, versatile and not expensive sources of X-gamma rays. New possibilities of improving the performances of the Compton sources are discussed. One of the methods for increasing the spectral density is based on the chirp of the laser. In this way, the oscillations and the broadening of the spectrum occurring in non linear regime can be eliminated, obtaining highly monochromatic signals. The occurrence of collective effects, taking place when the laser has high energy and long pulses permits to increase both the spectral density and the total number of photons. The control of polarization, the encoding of orbital momentum on the radiation and the possibility of producing two color radiation are also presented. Furthermore, the collisions between the gamma photons produced by two Compton scatterings provide an efficient way to test the QED photon-photon physics.

Speaker: Vittoria Petrillo (MI)

Slides petrillo_ch2016-inv.pdf

140 The ThomX X-ray source

The compact Compton ring ThomX is now under construction at LAL/Orsay. This machine will provide a quasi-monochromatic X-ray beam of multi keV energy. However major issues are expected in beam dynamics and on the operation of the laser system. In this presentation, the machine design, including the optical and laser systems will be reviewed. Recent progress in the optical system performances will be described. Some results obtained with an experimental setup at ATF/KEK will be given. Finally a description of the foreseen imaging and biological applications will also be given.

Speaker: Prof. Fabian Zomer (IN2P3/CNRS Université Paris 11)

Slides zomer_ch2016.pdf

141 Swift ion bunch acceleration by high power laser pulses

For approximately the last 20 years, laser-driven acceleration of ions has inspired novel applications that can benefit from interesting ion bunch properties. Those contrast conventional (non-laser based) accelerators by extremely short pulse durations in the picosecond range [1], a broad energy spectrum (~100 %), a high peak current (~kA) and a small, micrometer source size [2]. The main focus of research has been concentrating on the physics of the interaction of intense laser pulses with plasmas and the related mechanisms of ion acceleration, which I will review in this contribution. Special emphasis will be laid on the status and prospects of laser-driven ion acceleration in the emerging Petawatt-Laser era. Our group at the Ludwig-Maximilians University Munich is involved in the construction and commissioning of the Center for Advanced Laser Applications (CALA) [3] at the research campus in Garching near Munich. CALA will host one of the highest-power lasers in the world: the ATLAS 3000 laser system. It will be capable to provide a laser energy of up to 60 J in a pulse duration down to 20 fs, offering a peak power of 3000 Terawatts, which will be focused down to a few micrometer diameter. The high repetition rate of 1 Hz is beneficial for the development of enabling technology for future applications. The anticipated, high laser power promises a multitude of research possibilities, including developments towards radiation therapy of tumours, but also imminent applications which benefit from the unique features of laser-driven ion sources. One prime example, relies on the availability of heavy ion bunches such as gold, lead or thorium with solid-state-like densities for applications in non-linear nuclear physics in fission-fusion reactions to study the origin of heavy elements in the universe [4]. This work is supported by the DFG Cluster of Excellence MAP (Munich-Centre for Advanced Photonics), BMBF under contract 05P15WMENA and by DFG Transregio SFB TR18. References 1. B. Dromey et al., Nature communications 7, 10642 (2016) 2. H. Daido, M. Nishiuchi and A. S. Pirozhkov, Rep. Prog. Phys. 75(5), 056401 (2012). 3. http://www.lex-photonics.de/cala/ 4. D. Habs et al., Appl. Phys. B 103(2), 471–484 (2011).

Speaker: Mr Florian Lindner (Ludwig-Maximilians-Universität München)

Slides lindner_ch2016.pdf

142 Laser-Plasma Energetic Particle Production for Aneutronic Nuclear Fusion Experiments

The main interest in the aneutronic nuclear fusion reactions for energy production concerns the possibility of greatly reducing the problems associated with neutron activation and related requirements for biological shielding, remote handling, and safety. Among the so called “advanced fusion fuels” the proton-Boron fusion reaction seems to be the most attainable from an experimental point of view, due to the relatively high cross section of the process exhibited at the centre of mass kinetic energy of 148 KeV and 580 KeV respectively. An experiment has been performed at CELIA in which a multi-TeraWatt Ti:Sapphire laser interacted at fairly relativistic intensities with different solid targets. The experiment aim was to investigate two fusion processes, p-B and D-D, the first of which aneutronic. Al thin foils were used to produce energetic protons to be addressed to a Boron target, while deuterated-plastic targets were used to induce the D-D fusion reaction. Several diagnostics were activated to monitor the effectiveness of the laser-target interaction, the energy spectrum of the accelerated particles and the release of charged particles related to the activated fusion processes.

Speaker: Prof. Danilo Giulietti (PI)

Slides giulietti_ch2016.pdf

143 Short Pulse Diagnostics Improvements in the Vulcan Laser System

The Vulcan laser is a Nd:glass amplification chain that is capable of delivering up to 2.6 kJ in 8 beam lines in two target areas. Combined with 6 long pulse beams, with user selectable pulse length from 0.1ns to 8ns, short pulses are available with pulses down to 500fs using the Chirped Pulse Amplification (CPA) on two beam lines. Recently a new diagnostics system became operational, making the diagnostic data from the laser available to the User. To characterize the short pulse a new large window single shot autocorrelator was developed and is now operational. Also the contrast on the Petawatt beamline was investigated. Pre-pulses were identified and a new scheme of post-to-prepulse conversion was discovered. Finally, the new software for the analysis of the GRENOUILLE data developed in collaboration with University of Pisa is planned to be integrated with the diagnostic system. Also the characterization of the contrast in one of the two target area is under discussion, where new electrical noise mitigation will be setup in collaboration with the ENEA at Frascati.

Speaker: Dr Marco Galimberti (Science and Technology Facilities Council)

Slides galimberti_ch2016.pdf

144 Nonlinear Optics of the UV TW Laser Beam

A high-energy (up to 3 kJ in ns pulses) UV radiation (λ=248 nm) of KrF laser is successfully used in the Inertial Confinement Fusion (ICF) [1]. For ~ 1GW peak power in numerous angular multiplexed beams, nonlinear effects were not observed yet under propagation along ~100-m air path and in transmissive optics. TW peak power of sub-ps UV pulses at Ti:Sapphire/KrF GARPUN-MTW laser facility exceeds a critical power Pcr ≈ 100 MW and the laser beam becomes unstable in respect of Kerr self-focusing, and multiple filamentation arises [2]. It has a great impact on saturation of short pulse energy and optics degradation [3]. Therefore, suppression of beam filamentation is of high priority for the facility operation itself. On the other hand, filamented UV laser beam produces a bunch of partially ionized narrow plasma channels ranging to more than hundred meters in atmospheric air with a potential application for virtual sliding-mode MW waveguides [4]. Those might require regularizing of occasionally distributed filaments in the laser beam. The performed experiments at GARPUN-MTW laser purposed both these objectives. To suppress multiple filamentation we transferred 1-ps, 0.1-J linearly polarized output radiation through a 2.5-m length cell filled with Xe gas at pressure up to 1 atm. KrF radiation has a 2-photon resonance with Xe 6p [1/2]0 state, which causes unusual large negative nonlinear refractive index at KrF laser wavelength [5]. This should defocus high-intensity filaments in contrary with a common Kerr self-focusing in air and laser windows. As a result, in present experiments filaments with local peak intensity of ~ 0.2 TW/cm2, 200-fold higher than the average one, were homogenized to significantly lower intensity. Total energy loss in the cell of 20% was measured. Filamentation mitigation had a minor effect on the laser beam focusing. Remarkably, UV filaments in Xe produced a narrow-angle coherent cone emission at 828-nm wavelength. In a far-field zone, the IR light pattern looked like thin-wall rings surrounding individual filaments. Stimulated hyper-Raman scattering and amplified spontaneous emission at 6p [1/2]_0 → 6s [3/2]^0_1 transition of atomic Xe [6] may explain this emission. Amplitude masks with multiple apertures of different configurations were introduced in the beam and UV radiation distribution was measured behind the masks. A transformation from UV light diffraction patterns into regularized filaments structures was clearly observed with increasing the propagation distance. The research was supported by the RSF Project No. 14-12-00194 and by the RFBR Projects No. 15-02-09410 and 14-22-02021. References 1. S. Obenschain, R. Lehmberg, D. Kehne, et al., Appl. Opt. 54 (2015) F103. 2. V.D. Zvorykin, A.A. Ionin, A.O. Levchenko, et al., NIMB 355 (2015) 227. 3. V.D. Zvorykin, A.A. Ionin, A.O. Levchenko, et al., Quantum Electron. 44 (2014) 431. 4. V.D. Zvorykin, A.A. Ionin, A.O. Levchenko, et al., Appl. Opt. 53 (2014) I32. 5. R.H. Lehmberg, C.J. Pawley, A.V. Deniz, et al. Opt. Commun., 78 (1995) 78. 6. A. Tunnermann, K. Mossavi, B. Wellegehausen, Phys. Rev. A, 46 (1992) 2707.

Speaker: Dr Vladimir Zvorykin (P.N. Lebedev Physical Institute of Russian Academy of Sciences)

Slides zvorykin_ch2016.pdf

16:30 Coffee break

S5.2: Novel sources: FEL/Laser/Plasma channels

Convener: Danilo Giulietti (PI)

145 SPARC_LAB recent results and future perspectives

The SPARC_LAB test facility hosts a 150 MeV high brightness electron beam injector, which drives a FEL source, a THz radiation user beam line and an X-ray Thomson backscattering experiment. A particle driven plasma acceleration (PWFA) experiment is also under way. In parallel to that a 200 TW laser is linked to the linac and is devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration of electrons (LWFA) and of protons. Plasma-based acceleration has already proved the ability to reach ultra-high accelerating gradients. However the step towards the realization of a plasma-based accelerator still requires some effort to guarantee high brightness beams generation, diagnostics, stability and reliability. We describe in this talk the recent results in this regard achieved at the SPARC_LAB facility and the future perspective.

Speaker: Massimo Ferrario (LNF)

Slides ferrario-shpakov_ch2016-inv.pdf

146 The SPARC_LAB Thomson source upgrade

The SPARC_LAB Thomson source is a compact X-ray source based on the Thomson backscattering process. The electron beam energy ranges between 30 and 150 MeV, the electrons collide head-on with the Ti:Sapphire FLAME laser pulse the energy of which ranges between 1 and 5 J with pulse lengths in the 25 fs–10 ps range, providing an X-ray energy tunability in the range of 20–500 keV. After the second commissioning run of June 2015 a new Interaction Region has been designed to optimize the alignment of the two colliding beams and increase the so far obtained photon yield. To improve the electron beam diagnostic after collision a focusing doublet is now available in the electron dumping line that will also help in reducing the background contribution to the X-ray detector due to the electron beam divergence up to the absorber. The new setup is here presented.

Speaker: Cristina Vaccarezza (LNF)

Slides vaccarezza_ch2016.pdf

147 Development of optical resonant cavities for laser-Compton scattering

The power enhancement by an optical resonant cavity is a novel method to achieve intense laser pulses for laser Compton scattering, however, it requires high precision control of the optical path to keep it on the resonance. We have beeｎ developing a new scheme to avoid this difficulty using a feedback free optical cavity with self-reconating scheme. In this talk, we report the status of the R&D of the new scheme. We also report about the status of photon generation experiment by laser Compton scattering at KEK.

Speaker: Tohru Takahashi (Hiroshima University)

Slides Channeling2016-takahashi-v2.pptx

148 Observation of elastic photon-photon scattering events using collider based on Compton gamma sources.

We present the design of a photon-photon collider based on Compton gamma sources for the observation of elastic γγ scattering. Two symmetric relativistic electron beams produce two primary gamma rays through Compton back scattering with two high energy lasers. The elastic photon-photon scattering is analysed by start-to-end simulations from the photocathodes to the detector. A new Monte Carlo code has been developed ad hoc for the counting of the QED events. Realistic numbers of the secondary gamma yield, obtained by using the parameters of existing or approved Compton devices, a discussion of the feasibility of the experiment and of the nature of the background are presented.

Speaker: Illya Drebot (M)

Slides drebot_ch2016.pdf

149 Plasma-discharge undulator

The plasma wake-field acceleration (PWFA) is the promising type of acceleration, that recently had shown not only ability to produce a high energy beams at short distance, but also increasing quality of the beam in terms of energy spread, emittance and stability. Increasing quality of the PWFA beams opes for us an opportunity to create a compact FEL type sources of radiation. In this work we studied a possibility to use a capillary plsama-discharge, as cheaper substitution for conventional magnetic undulators, to produce a narrow band high brightness radiation.

Speaker: Vladimir Shpakov (LNF)

Slides ferrario-shpakov_ch2016-inv.pdf

150 Betatron radiation from electrons accelerated in laser-produced plasma channels

The betatron radiation from electrons accelerated in laser-produced plasma channels typically extends in the X-ray region, with a broad synchrotron-like incoherent spectrum. Nevertheless the radiation spectrum and the degree of coherence of the betatron radiation can be efficiently modified according to different laser-plasma interaction schemes. The betatron radiation seems to be a good candidate both to be exploited as brilliant ultra-short X-ray source and for diagnostics of the electrons accelerated in the plasma channels.

Speaker: Alessandro Curcio (LNF)

Slides curcio_ch2016.pdf

PS3: Poster session

151 A proposal for Axion-Like Particle search with Free Electron Lasers

The development of intense and coherent electromagnetic sources offers novel pathways in the search for new particles and exotic phenomena. A recently growing interest is dedicated to the low mass particle candidates of Dark Matter. We envisage the possibility of developing a multipurpose facility dedicated to the search of Axion-Like Particles, ALPs, based on the use of Free Electron Laser (FEL) Oscillators. The proposal is based on an extension of the Light-Shining-through-Wall principle and aims at integrating different techniques to enhance the production of so rare a signal. Taking also account the chance of a wavelength scan by means of Compton backscattering, we discuss some FEL oscillator configurations where radiation intensity and wavelength allow to probe ALPs parameters not yet excluded by presently operating experiments. In particular, with an electron beam energy of a few hundreds MeV, we can probe both the region hinted by an enhanced cooling mechanism in white dwarfs and -- after Compton backscattering -- the few keV ALP mass range, at the limit of the past direct search for solar axions.

Speaker: Federico Nguyen (LNF)

152 Channeling Of Low Energy Atomic Particles In Carbon Nanotubes With Heterojunctions

Channeling of low energy atomic particles in carbon naotubes is interesting for low energy ion implantation, local ion plasma enhanced deposition, chemicaly-biological and medical atomic particles transport application [1]. Carbon nanotubes sre useful as ion beam management system parts. Temperature variating along the nanotube production process allow us to variate CNT diameter, which creates nanotube heterojunction [2]. Each heterojunction could be use as an apperture for the ion beam. In this work CNT the heterojunction influence on low energy ion channeling is studied. Impact ions is randomly distributed along CNT crosssection. Ion impact angle is variated in 1.4 ° range and initial azimuthal angle is randomly distributed. Ion with start energy about 300 eV per nucleus and initial angle by 15° channeled through the heterojunction will be shown. For example, (20,0)/(10,10) heterojunction is effective as apperture and decrease initial ion beam diameter up to 20 %. References 1. Z.L. Mišković, Radiation Effects and Defects in Solids 162 (2007) 185. 2. Y. Yao, et al., Nat Mater, 6 (2007) 283

Speaker: Dr Gennadiy Filippov (Cheboksary Polytechnic Institute)

153 Coherent radiation of relativistic electrons in metamaterials based on the SRR/wire-grid unit cell in millimeter wavelength range

In this report we present experimental investigation of interaction of the electromagnetic field of a relativistic bunched electron beam with a metamaterial. Used metamaterial target represents a right triangular prism. The unit cell of the target consists of a split-ring resonator (SRR) and a wire. The size of the unit cell is 3 mm. The measurements were done in millimeter wavelength range in far field zone using relativistic electron beam with energy of 6 MeV. The measured angular dependencies show that the radiation generated by the electron bunches moving near the target is observed in the backward semi-sphere. In approximation of scalar refractive index the obtained result can be interpreted as the reversed Cherenkov radiation.

Speaker: Ms Veronika Soboleva (National Research Tomsk Polytechnic University)

154 Computer Simulations of Particle Beams Motion into Capillaries

Advanced computer technology and wide use of personal computers today open up great perspectives of computer simulations for studying various processes and phenomena of the surrounding world. Computer models are often used to obtain new data about simulated object or for approximate estimation of the system behaviour while this system is too complex for analytical exploration. Consistency of computer models allows both the main factors that determine the properties of simulated objects to be identified and the response of the simulated system to change of its parameters or initial conditions to be explored. In this paper we implemented the program (CapStruct) in its first version that simulates the passage of neutral particle beams in capillary structures in dependence on both geometry of these structures and beams parameters. This program calculates and graphically depicts distributions of particles on the detector depending on following parameters: the shape of the capillary (cylindrical, toroidal or conical), the position of the capillary, the internal radius, the capillary length, the curvature and the angle of rotation (for toroidal capillary), the opening angle (for conical capillary) and parameters of the roughness of the capillary’s inner surface. CapStruct allows simulating the propagation of parallel as well as divergent beams in variation of the following parameters: the amount of particles, the absolute value and the direction of the particle velocity, the angle of solution (for a divergent beam). The parameters of the distribution of particles in the beam at the initial time also can be varied. For this version the code both particle size and interaction between them was not considered. This computer model was constructed in the approximation of elastic interaction of particles with a capillary surface, the loss of energy at the reflection of particles was neglected. All models are characterized by a significant simplification of the processes of interaction of the beams with surface. This simplification, which characterizes our code in the first version, becomes very important in order to study in details all structural features of such interaction. The latter enables preserving future developed codes from any errors due to geometrical factors of the system under evaluation that is typically very crucial point for multi systems. Thus, this work is the basis for solving more complex problem in the future - simulation of charged particle beams motion into capillary structures.

Speaker: Egor Kurnikov (NRNU MEPhI)

155 Crystal parameters optimization for enhancement of deflection efficiency of fast charged particles

There are three fundamentally different mechanism of deflection of fast charged particle beam by a bent crystal. The first mechanism was proposed by E.A. Tsyganov [1], and is based on the phenomenon of planar channeling of charged particles in a bent crystal. The second, proposed by A.M. Taratin and S.A. Vorobiev [2], called the "volume reflection", is a single reflection of positive charged particles by bent crystal plane. And the third one, proposed by A.A. Greenenko and N.F. Shulga [3], is based on multiple stochastic scattering mainly above-barrier particles by atomic chains of a bent crystal. All these mechanisms have their advantages and disadvantages, and the choice of this or that mechanism should be based on a special analysis and optimization of all parameters for each mechanism separately and for each particular purpose. We present the results of such analysis and the search for optimal parameters, such as type of crystal, its orientation and bending, temperature effect and others to achieve the most efficient use of a bent crystal for deflection of fast charged particles. This analysis is based on computer simulation of the passage of relativistic charged particles through a bent crystal along crystallographic axes or planes. The usage of the binary collisions model allows to take into account the thermal vibrations of atoms in the crystal lattice in the most direct way and therefore, to analyze the temperature effects on the stability of the motion regime and efficiency of its use for particle deflection. Considering the crystal as a periodical 3d system of discrete atoms, this model allows to describe the transitions between different motion modes such as axis-plane in unified approach. These studies are conducted in the framework of the International Associated Laboratory "The development of detector systems for experiments in accelerators and technology for physics accelerators" (Ukraine-France) and provided by the grant support of the State Fund For Fundamental Research (project F64/17-2016) and the National Academy of Science of Ukraine (project F5-2016). References 1. E.N. Tsyganov, Preprint Fermilab TM-682, TM-684, (1976) 2. A.M. Taratin, S.A. Vorobiev, NIM B 26 (1987) 512 3. A.A. Greenenko, N.F. Shul’ga, JETP Lett. 54 (1991) 524

Speaker: Mr Oleksiy Fomin (Laboratoire de l’Accélérateur Linéaire, CNRS et Université Paris-Sud, Orsay, France)

156 Design of a Watt-level gamma-ray source based on high-repetition-rate inverse Compton Scattering

A high-brilliance ($>10^{20}$ phot.s$^{-1}$.mm$^{-2}$.mrd$^{-2}$/0.1%) gamma-ray source experiment is currently in preparation at Fermilab ($E_\gamma\simeq 1.1$~MeV). The source implements a high-repetition-rate inverse Compton scattering by colliding electron bunches formed in a 300-MeV superconducting linac with a high-intensity laser pulse. This contribution describes the design rationale along with technical challenges associated to producing high-repetition-rate collision (e.g. development of a coherent stacking cavity). The expected performances of the gamma-ray source are also presented along with their sensitivity to fluctuations of electron-beam and laser parameters.

Speaker: Philippe Piot (northern Illinois University &amp; Fermilab)

157 Double crystal-based collimation system for high-energy accelerators

The crystal-based collimation system is a potentially efficient solution for the collider beam halo collimation problem. However it is not free from the leakage from secondary collimators and incoherent nuclear scattering in crystal primary collimators, mainly connected with dechanneling process. To solve this problem, we propose here a double crystal-based collimation system, with the second crystal oriented in the transverse direction between the primary crystal collimator and the secondary collimator. The second crystal will amplify the deflection of particles with the amplitudes of betatron oscillations too high for the capture in the channeling mode. We propose to use the multiple volume reflection in one bent crystal in this second crystal collimator. We consider the same effect in a sequence of bent crystals as well as compare it with single volume reflections in a sequence. In its turn, for the primary crystal collimator we suggest channeling in skew crystal planes to lower the requirements on crystal alignment as well as to use multiple volume reflection instead of the single one for non-channeled particles. In addition, we propose to considerably increase the channeling efficiency in the first crystal by application of a narrow plane cut. We simulate all the cases with CRYSTAL simulation code on the CINECA supercomputers and acknowledge the CINECA award under the ISCRA initiative for the availability of high performance computing resources and support.

Speaker: Alexei Sytov (FE)

158 Dynamics of the Relativistic Particles and Conformal Mapping of the Crystal

Dynamics of the Relativistic Particles and Conformal Mapping of the Crystal G.V. Kovalev School of Mathematics, University of Minnesota, Minneapolis, MN 55455,USA The dynamics of relativistic particles is depended on the shape of the crystals and beam optics. The bending of the crystal is possible in many ways. One of the most powerful and natural way to find the needed bent is the using the conformal transformations or conformal mappings in which the crystal can be bent in 2D space with preservation of the angles between all crystal axes. If the original shape of a crystal is parallelepiped with coordinate system x,y,z and the bent is done around the axis z, the conformal bent must be such that the complex transformation x+iy = f(ξ +iη) is satisfied. Here f(x) is any real function which can be written in complex form as f(ξ+iη) = u(x,y)+iv(x,y) where functions u(x,y), v(x,y) are called harmonic and they satisfy Cauchy-Riemann equations. For example, the first steering crystals were manufactured in circular bent, which correspond to conformal transformation x + iy =e^(a(ξ+iη)), a is a constant. Many others bents are possible, for example x + iy = (ξ + iη)^n or x + i y = sin(ξ + iη), but most of them did not considered. Purpose of this report is to consider some of them. There is obviously infinite number of conformal coordinate systems and therefore suitable bents of the crystal and all of them have the orthogonal properties. Of course, not all of them can be manufactured, but plenty of them can be approximated in order to give the optimal bent of crystal. References [1] P.M. Morse, H. Feshbach, Methods of Theoretical Physics, vol. 1, Ch. 4-5, McGraw-Hill Book Co., New York, 1953.

Speaker: Dr Gennady Kovalev (U of M)

159 Fast Beam Pointing Stabilization for High Power Laser System

Electron acceleration using short pulse high power laser is one of the scheme proposed to reduce the size of the future accelerator. Different scheme has been proposed to increase the acceleration length and the final electron energy, like use of gas filled capillary. Advance target design increases the demand on the quality of the laser beam, in particular to the pointing stability, that it is required to be better than the focal spot, of the order of few microradian. A point stability of that level is difficult to achieve on large size high power lasers, where the laser system span on different rooms and/or floors. Those systems could also be subjected to external vibrations, i.e. produced by other facilities nearby. In this communication we present the development of a beam stabilization system able to operate a 3in mirror with sub-millisecond response time and it is capable to suppress 50Hz vibration by a factor 10. This system is planned to be tested on the PW class TiSa laser Gemini at Central Laser Facility.

Speaker: Dr Marco Galimberti (Science and Technology Facilities Council)

160 Features of Cherenkov Radiation at Channeling

In the report the features of Cherenkov radiation at channeling are investigated

Speaker: Prof. Vladimir Vysotskii (Kiev National Shevchenko Univ)

161 Hadron Photon Colliders as photo-cathode sources of low emittance muon beams

We discuss the possibility to generate low emittance muon beams by colliding high energy hadrons and counterpropagating high brilliance photon pulses. The asymmetric collision of Large Hadron Collider/Future Circular Collider like hadrons and FEL keV photons imparts a strong Lorentz boost to the secondary particles which are emitted at hundreds GeV energy within a small angle around the hadron beam propagation axis. The phase spaces of the emitted particles are simulated by means of an event-generator code and the characteristics of the muon beams are compared to the analytical calculations. The brightness of the secondary (muon, pion, neutrino, electron, positron) beams is calculated and a preliminary evaluation of the hadron beam degradation after the interaction is given.

Speaker: Camilla Curatolo (MI)

162 Hard X-rays with controlled parameters

In order to gain control over hard X-ray (over 30 keV), X-ray diffraction in Laue geometry (over 30 keV) from a single crystal of quartz influenced by the temperature gradient has been considered. It has been experimentally proved that the intensity of the reflected beam can be increased up to several orders if the X-ray energies are 30 keV and 40 keV for reflecting atomic planes (10-11) depending on the value of the temperature gradient. It has been shown that with an increase in the temperature gradient the focus becomes closer to the crystal, the focal spot narrows in the diffraction plane and the integral intensity increases tenfold.

Speaker: Dr Vahan Kocharyan (Institute of Applied Problems of Physics of NAS RA, 0014, Hr. Nersisyan str. 25, Yerevan, Armenia. National Research Tomsk Polytechnic University 634050, Lenin Avenue 30, Tomsk, Russia.)

163 High Energy Microbeams and Focusing Limits of Channeling Particles

High Energy Microbeams and Focusing Limits of Channeling Particles G.V. Kovalev School of Mathematics, University of Minnesota, Minneapolis, MN 55455,USA The possibility of beam steering of high energy particles by a crystal has been investigated for a long time. Tsyganov was the first who proposed the bent crystal channeling. After the successful demonstration of the bent channeling[2], it became clear that bent crystals can be used for constructing a focusing element with extremely short focal length and focal spot close to size of one atomic channel. Several crystal devices for focusing were suggested [3-4]. Their common idea is based on differently bent plane channels to provide a 1-D beam convergence to a focal point. Because the crystal planes are naturally parallel, the focusing device must exert an external force making channels converged. Carrigan[3] suggested a simple solution where a monocrystal is partially cut into thin parallel slices with empty gaps between them. To focus the beam the slices should be pressed together. Another solution is to apply a strong external pressure providing channel's convergence of the bulk crystal. The further improvement in this direction are led to mixed crystals with smooth change in the lattice constant. Similar constructions with graded composition layers were suggested and tested for a deflection of particles. All other developments[5] and suggestions are discussed in this work. References [1] E. N. Tsyganov, Some aspects of the mechanism of a charge particle penetration through a monocrystal, Fermilab,TM-682 (1976) 5. [2] Y. N. Adishchev, et al, JETP lett. 30 (1979) 402. [3] R. A. Carrigan, On the possible applications of the steering of charged particles by bent single crystal, Fermilab FN-80/45 (1980) 46. [4] R. A. Carrigan, The application of channeling in bent crystals to charged particle beams, in: R. A.Carrigan, J. A. Ellison (Eds.), Relativistic Channeling. Plenum, New York, 1987, pp. 339-368. [5] G. V. Kovalev, Nucl. Instr. and Meth. in Phis. Res. B 207, pp. 428-486.

Speaker: Dr Gennady Kovalev (U of M)

164 LAUe-PEak Radiotherapy (LAUPER)

The LAUPER project aims to demonstrate the feasibility of a Laue lens optimized to operate with X-rays emitted by a conventional X-ray tube to produce a focused photon beam for radiotherapy applications. In the context of tumor treatment, radiotherapy is an important method consisting in imparting a radiation dose to a target volume in order to destroy cancer cells. Any radiotherapy treatment aims to maximize the dose to the target volume, minimizing at the same time the irradiation of neighboring healthy tissues. Among radiotherapy treatments, hadron therapy uses charged particles beams, namely protons or positive ions, to achieve the aforementioned goal. Indeed, positive ions have a finite range of penetration in a tissue and a high amount of energy released at the end of their track (the Bragg peak). However, the cost of a facility for hadron therapy is very high, at least 100 Me. Only a few dozen of hadron therapy facilities exist in the world, and half of them are concentrated in the United States and in Japan. Thus, only a limited number of patients can access to the high-quality treatment provided by hadron therapy. Conventional radiotherapy relies on electron linear accelerator producing photon beams in the MeV energy range to reach the tumor target and spare the skin. However, such technique is not comparable with the hadron therapy in terms of dose deposition accuracy. The cost of a facility for conventional X-ray treatments ranges in 1-2 M€. A device capable of focusing X-rays would allow concentrating the delivered dose in a target volume. Due to focalization, the photon flux would increase with the penetration depth in the tissue and would reach the maximum at the focal point. The combination of this effect with the photon absorption would give rise to a depth-dose profile showing a pronounced peak at focal point and a rather rapid fall-off beyond this point. This behavior resembles that of a Bragg peak, typical of hadron therapy, resulting in a “Laue peak”. In order to concentrate an X-ray beam, the phenomenon of diffraction can be exploited. A proposed optics is the Laue lens, namely an ensemble of crystals arranged in concentric rings and disposed in such a way to diffract as much radiation as possible toward the focal point of the lens, where the tumor mass is positioned. As sketched in Fig. 1, such a focusing device can be used together with a conventional X-ray tube to focus photons in the energy range 25-250 keV. Thus, it would be possible to reach high precision in the dose delivery with an equipment orders of magnitude less expensive if compared to the cost of a facility for hadron therapy. Indeed, the cost of such equipment would be in the range of 0.2-0.3 M€, even less expensive than the equipment for traditional radiotherapy based on MeV X-ray beams. During this project, we aim to construct a crystal assembly capable of diffracting an 80 keV X-ray beam and producing the aforementioned Laue peak in a proper phantom.

Speaker: Andrea Mazzolari (FE)

165 Measurementes of the high-efficiency deflection of 400 GeV/c protons due to channeling along the <110> axis of a bent silicon crystal

Bent silicon crystals have been measured to deflect 400 GeV/c protons thanks to channeling along the <110> axis with a 61 % efficiency. This is found to be comparable with the deflection efficiency due to planar channeling and considerably larger than in the case of the <111> axis . Besides, the probabilities of inelastic nuclear interactions of protons crossing the crystal are measured in channeling conditions relatively to a crystal random orientation and found to be 10 % for the channeling along the <110> axis and 25 % for channeling within the (110) planes. High efficiency deflection and relatively small losses due to inelastic interactions make this axial orientation of a silicon crystal a useful tool for the beam steering of high energy charged particles.

Speaker: Enrico Bagli (FE)

166 Micron Scale Electron Beam Size Measurements Using Optical Transition Radiation

Optical transition radiation (OTR) is widely used as a tool for transverse diagnostic of electron beams in many accelerator facilities around the world. It is generated when the beam of electrons intercepts a metallic or dielectric screen. The OTR then propagates in the direction of the mirror reflection to the point where it can be detected. Despite the fact that the electron beam can be destroyed by the target it still can be used as a supplementary monitor in addition to the main diagnostics. Conventionally, the beam size can be extracted directly from the OTR images, however with this approach the resolution is limited to only a few micrometers which is not sufficient for future high energy machines such as CLIC or ILC. It has been shown [1] that the resolution can be dramatically increased by analyzing spatial properties of the OTR vertical polarization. This method was firstly developed and tested at the Accelerator Test Facility 2 (ATF2) in KEK in 2011. Later, during the operation in 2013 this beam profile monitor has successfully demonstrated the ability to measure the beam size of less than one micrometer. At the same time it has been proved experimentally [2] and by simulations [3] that the performance of the optical system directly affects the quality of the beam size measurements. In order to minimize the effects caused by the optical system and push the resolution of the measurements even further the whole experimental setup has been recently upgraded. The main feature of this major upgrade, developed in collaboration between CERN, John Adams Institute and KEK, is inserting the main optical element ( first focusing lens) into the vacuum, as close as possible to the target, in order to minimize aberration effects. In this report we will present the current status of the experiment, discuss recent experimental results and future plans. References [1] P. Karataev, et. al., Phys. Rev. Lett. 107 (2011) 174801. [2] K. Kruchinin, et. al., Journal of Physics: Conference Series 517 (2014) 012011. [3] B. Bolzon, et. al., Phys. Rev. ST Accel. Beams 18 (2015) 082803.

Speaker: Dr Konstantin Kruchinin (Royal Holloway, University of London)

167 Non-divergent surface waves from charged particle bunch moving along semi-infinite wire planar structure

In this work, we continue investigations of non-divergent radiation in volume and planar wire structures with small period. Unlike previous works, we consider the bunches moving along the semi-infinite planar wire structure. Besides, we consider not only thin bunches, but also bunches with finite cross-section. We analyze surface waves generated by a charged-particle bunch at the semi-infinite planar periodic wire structure. It is supposed that the bunch moves parallel to the edge of the structure and perpendicularly to wires. The influence of the grid is described by the averaged boundary conditions. Initially, we consider bunches with negligible thickness and finite length. Further, bunches with finite thickness are considered as well. The analytical results are given for a general case, which takes into account the finite period of the structure and wires radius. It is shown that the surface waves excited by the bunch propagate along wires with the speed of light in vacuum. The number and the structure of these surface waves depend on relative location of the bunch path and the grid. One type of wave is always excited, but its magnitude decreases with distance from the bunch to the structure edge. If the bunch projection falls on the half-plane occupied by wires, then additionally three surface waves are generated: two of them are equivalent to ones excited at infinite wire structure and another one is a surface wave reflected from the edge. Typical numerical results are presented. They show that the structure of surface waves allows to determine both the length and the thickness of the bunches.

Speaker: Dr Sergey Galyamin (Saint Petersburg State University)

168 On charged particles propagation through microcapillaries

The interaction of a charged particle with a curved inner surface of a capillary and influence of its curvature on the process of particle deflection are analyzed. The results were obtained using perturbation theory.

Speaker: Mrs Ekaterina Dik (NRNU MEPHI)

169 On Transverse X Beam Profile Transmitted by Polycapillary Semi Lens

Polycapillary optics is a well known technology used within different research and industrial fields. Generally these devices are applied for their integral properties, as flux gain factor, or for the micro- focus features useful for confocal geometry. Less investigations have been spent about composition of the trasmitted beam. In this work features about spot size, energy composition, residual divergence and energy spectra of the beam are investigated. Specifically these features have been measured as a function of ending face radius of polycapillary semi lens. At last, the same investigation has been led for a imaging case study as a validating experiment of previous conclusions.

Speaker: Andrea Liedl (LNF)

170 Quantitative theory of dechanneling in bent and straight single crystals.

Based on results of paper [1] devoted to study of volume reflection and volume capture we develope the so name "one-trajectory approximation of a diffusion process" for conditions of channeling process in straight and bent single crystals. We extend this approximation for a sufficiently long crystals. We also consider posively and negatively charged hadron beams. References [1] S. Bellucci, Yu. A. Chesnokov, V. A. Maisheev, and I. A. Yazynin PhysRevSTAB.18.114701 (2015).

Speaker: Dr Vladimir Maisheev (IHEP, Protvino, Russia)

171 Quasichanneling oscillations in the deflection angle distribution in a bent crystal

Charged particles under over-barrier states but still close to channeling conditions experience transverse oscillations named quasichanneling oscillations. We demonstrate both theoretically and by Monte Carlo simulations that such kind of oscillations can be directly observed in the deflection angle distribution behind a bent crystal for both positively and negatively charged particles. We provide a theoretical interpretation for them as well as discuss their pecularities for (110) and (111) planes in a silicon crystal. We optimize realistic experimental conditions for their observation as well as energy scaling of these conditions. In addition, we discuss the possibility of application of quasichanneling oscillations in the deflection angle distribution to measure the radius of bent crystal and the angle of crystal alignment.

Speaker: Alexei Sytov (FE)

172 Some features of grazing interaction of 10 keV electrons with dielectric surfaces

The analysis of experimental data obtained in the study of grazing interaction of fast electron beams with flat dielectric surfaces demonstrates a dependence of the surface charge distribution formation on the dielectric material. We found that the angular distribution of the electron beam does not depend strongly neither on the length of the surfaces nor on the beam current. In addition, the new experimental results concerning the grazing interaction of 10 keV electrons with metallized structured surfaces show a clear difference from similar experiments with flat surfaces. The work was supported by a program of the ministry of education and science of The Russian Federation for higher education establishments, project № 14.578.21.0063 (RFMEFI57814X0063).

Speaker: Dr Alexander Kubankin (Belgorod National Research University)

173 Spiral Scattering of Relativistic Particles in a Bent Crystal

Spiral Scattering of Relativistic Particles in a Bent Crystal G.V. Kovalev School of Mathematics, University of Minnesota, Minneapolis, MN 55455,USA The spiral scattering of charged particle occurs due to the appearance of a negative logarithmic singularity of the classical deflection function χ(b) of a particle for a certain impact parameter b = bs[1,2]. Resonance scattering [3] is a quantum-mechanical analog of spiral scattering [2] and can be considered as a general effect which includes the wide class of quantum-mechanical phenomena. In particular, it can appear in the scattering of relatively slow particles by a cylindrical well (see, e.g., [3]), whereas the classical spiral scattering by such a potential is absent [4]. The spiral scattering is also different from channeling motion where the particle undergoes periodic reflection from the wall of atoms of the lattice. The present work illustrates this feature and several others and determine the spiral scattering boundaries using more real potentials than in [2]. As was pointed in [2] the the spiral scattering has the optimal range ∆bs and this range is analyzed for real potentials. For real smooth potential, the spiral scattering still exists, but the character of singularity is different from the logarithmic singularity considered by Ford and Wheeler [1]. In this case the real potential has inflection point and this gives the inverse square root singularity. Therefor, in this case the spiral scattering and deflection should take place too. References [1] K. W. Ford and J. A. Wheeler, Ann. Phys. 7, 259 (1959). [2] G.V.Kovalev, JETP Letters, 89, No. 6, 265, (2009). [3] N.P.Kalashnikov, G.V.Kovalev, JETP Letters, 29, 302, (1979). [2] G.V.Kovalev, JETP Letters, 87, 94, (2008).

Speaker: Dr Gennady Kovalev (U of M)

174 The policapillary optics application for double diffraction line intensity increase

Nowadays X-ray absorption spectroscopy is widely used in the X-ray structural analysis [1] and can be applied to elemental analysis of substance [2]. A special group of absorption analysis methods imply measurements of the radiation absorption coefficients at a few energy lines that allow estimating a number of investigated object characteristics. Implementation of these methods requires X-ray beams with line spectrum, which is a sum of a two or more energy line. Authors propose [3] to use combination of X-ray tube and a set of crystal monochromators, which are reflect X-ray lines with different energies in the one direction, to produce such beams. This can be used as an alternative to currently using radioactive sources. In the report possibility of use X-ray polycapillary half-lens in order to increase intensity of a couple X-ray lines produced by this scheme is considered and experimental investigation results are shown. In the experiment, X-ray tube (Oxford Series 5000) with molybdenum anode was used as a source and set of crystals, which were silicon (100) and (111), were used to produce line spectrum. The obtained results approve the possibility to increase X-ray lines intensity to more than one order of magnitude. References 1. Bunker G 2010 Introduction to XAFS: A Practical Guide to X-ray Absorption Fine Structure Spectroscopy (New York: Cambridge University Press). 2. A. Gogolev, Yu. Cherepennikov, Device for X-ray spectral absorption analysis with use of acoustic monochromator, Journal of Physics: Conference Series, V. 517, Article number 012037 (2014) 1-5. 3. Gogolev A.S., Cherepennikov Yu.M., Vukolov A.V. et al. WD-XRA technique in multiphase flow measuring, Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, V. 355. (2015) 276–280

Speaker: Mr Yury Cherepennikov (Tomsk Polytechnical University)

175 X-ray investigation of the needle cellular structure by polycapillary optics and lithium fluoride detectors

The tree plantation conditions are the one of the most sensitive indicators of environmental state. The high levels of correlation relationships between morphological and physiological parameters of needle and toxicological loads were established [1]. It is known, that woody plants are highly sensitive to anthropogenic load, so they can serve as adequate indicators of the ecosystems condition [2-3]. There are several routes of chemical elements and compounds entry into the plants, the main of which are root absorption, gaseous exchange and exchange adsorption on the lamina surface. In the towns and suburbs among woody plants the major part are conifers, which show a high sensitivity to environmental changes. The analysis of the needle anatomical features demonstrated that for all investigated coniferous species under the technogenic stress conditions the resin channels area was decreased, and there were other changes in the cellular structure [4]. The standard algorithm of the needle anatomical structure investigation consists of the following steps: the needles are fixed using ethanol or glycerol, then the slices from the needle middle part are made by freezing microtome, after that the samples are analyzed by optical microscope, for example, by Axiostar plus light microscope (Karl Zeiss, Germany) [4]. However, this approach has some disadvantages. The main problem is that for the cell wall thickness measurements either the optical zoom is insufficient or the flares appear on image at high magnification. A method based on the use of X-ray projections on the lithium fluoride detectors with the application of polycapillary optics is proposed in order to obtain more sharp images of the needle cross sections [5]. The radiation generated by the X-ray tube, passes through polycapillary half-lens forming a quasi-parallel beam. Then the partly absorbed in the sample radiation falls on the LiF detector and produces an X-ray image. After that, the image on the LiF crystal is analyzed by microscopic investigation. It is expected, that such kind of data will be devoid of the standard method disadvantages and allow investigating the needle cellular structure more precisely, and that will increase the efficiency of the method of the environmental state estimation by condition of plants. References 1. A. N. D. Auclair, H. C. Martin, S. L. Walker, Water, Air, and Soil Pollution 53 (1990) P. 13-31. 2. Ganon J.A., Qiu H.L. Ecological Application of Remote Sensing at Multiple Scale // Handbook of Functional Plant Ecology // Ed. by F.I. Pugnare, F. Valladores N.Y.: Marcel Dekker, 1999. P. 805-846. 3. H.K. Lichtenthaler, J. Plant Physiol. 148 (1996) P. 4-14. 4. A. P. Zotikova, O. G. Bender, R.O. Sobchak, T. P. Astafurova, Tomsk State University J. 299 (2007) P. 197-200. 5. D. Hampai, S. B. Dabagov, G. Della Ventura, F. Bellatreccia, M. Magi, F. Bonfigli, R. M. Montereali, EPL, 96 (2011) 60010.

Speaker: Mr Sergei Stuchebrov (Tomsk Polytechnic University)

176 X-ray optics for exotic atoms experiments

SIDDHARTA-2 aims to perform the first measurement of the kaonic deuterium transitions, which, combined with the result on kaonic hydrogen, will deliver the isospin-dependent kaon-nucleon scattering lengths, fundamental to low-energy QCD. A related experiment, using the new Transition Edge detectors has been successively proposed, for accurate determination of the controversial k- mass and for measuring other exotic atoms requiring eV precision. Investigating the use of TES microcalorimeters for X-ray transitions in strongly interacting systems, the idea of including polycapillary optics came naturally, considering the gain in both signal and shielding efficiency. Several under-study topologies will be presented.

Speaker: Mihail Antoniu Iliescu (LNF)

Friday, 30 September

W2.1: The 8th AGTaX workshop “Advanced Generation of THz and X-ray beams

Convener: Dr Alexey Tishchenko (National Research Nuclear University "MEPhI")

177 Advanced Generation of THz and X-ray Beams Using Compact Electron Accelerator

A compact accelerator facility designed to generate high-brightness electron beams is of great demand throughout a broad scientific community as it can be used to generate intense, tunable THz and X-ray radiation beams. The “Advanced Generation of THz and X-ray” (AGTaX) collaboration was created to bring together different communities working on the simulation, generation and experimental investigation of radiation beams as well as on accelerator subsystems design and optimization. A technical challenge of compact accelerator projects such as LUCX [1], DLS [2] and MEPhI [3] is the generation of extremely short, pre-bunched beams with hundred femtosecond length and period without external longitudinal phase space compression. This challenge extends to four distinct issues: creating small emittance beams, preserving the emittance during acceleration and transport, utilizing the beams for radiation generation which includes coherent Transition, Smith-Purcell, Cherenkov, Undulator (THz FEL) radiation and Compton X-Rays, and finally to characterizing the radiation properties. Additionally longitudinal beam diagnostics techniques should be adapted for modulated beams. In this report the present collaboration projects will be reviewed and a roadmap for future developments will be discussed.

Speaker: Dr Alexander Aryshev (KEK)

Slides aryshev_ch2016-2.pdf

178 Study of the Polarization Properties of Coherent Smith-Purcell Radiation at the LUCX (KEK) facility

A study of the polarization of coherent Smith-Purcell Radiation (cSPr) has been carried out at the LUCX (KEK) facility using an 8 MeV electron beam. Two orthogonal polarizations of the radiation were measured and the degree of polarization was calculated. The experimental result was compared to simulation results calculated using a semi-analytical surface current model. Two dimensional scans were carried out in order to study the intensity distribution of cSPr for both polarizations. Potential applications of highly polarized cSPr to longitudinal beam diagnostics are discussed with respect to the results presented.

Speaker: Ms Hannah Harrison (University of Oxford)

Slides harrison_ch2016.pdf

179 Preliminary results for Smith-Purcell radiation from a skewed planar grating using the surface current model

Preliminary intensity distributions for Smith-Purcell radiation generated by a grating with its period skewed with respect to the propagation direction of the particle beam will be presented. The results have been obtained using the well-established surface current model. An outline of the calculations will be described, along with qualitative descriptions of the radiation distributions generated using both finite and quasi-infinite planar gratings. The form of the radiation distributions compares favourably with that predicted by the conical diffraction radiation model of Sergeeva et. al. The use of skewed gratings could simplify the construction of a future single-shot longitudinal beam profile monitor.

Speaker: Dr Andrew Lancaster (University of Oxford)

Slides lancaster_ch2016.pdf

180 Experimental Investigations of THz radiation from composite corrugated capillary with reflector

In this report we present experimental investigations of the THz radiation generated from a corrugated capillary and a blank capillary with reflectors, using a femtosecond electron beam of LUCX accelerator at KEK, Japan. LUCX is capable of generating a train of 4 bunches each with 150 µm (500 fs) duration and 200 µm transverse size. We present measurements of the angular distributions of the THz radiation generated from the corrugated and blank capillary, and their comparison with Particle In Cell (PIC) simulations. We also discuss off-central propagation of the beam in the capillary based on the experimental measurements, PIC simulations and analytical studies.

Speaker: Dr Konstantin Lekomtsev (Royal Holloway University of London)

Slides lekomtsev_ch2016.pdf

181 Influence of a Space Charge Effect in a Femtosecond Electron Beam on Coherent Transition Radiation Spectrum

The coherent radiation generated by a short electron bunches is well studied and finds a broad application for different scientific communities. However, the improvement projects towards the implementation of the compact accelerator system providing the high-charge and ultra short electron bunches are still attractive and open up a new possibility of the high-brightness coherent radiation generation. Recently it was shown that a photocathode RF gun can produce a femtosecond electron beam with low-charge [1] without magnetic compression techniques. For the case of high-charge beam a space charge effect dramatically increases the bunch sizes and the spectrum of coherent radiation is also changed. In this report we discuss the space charge effect suppression techniques. Using ASTRA software we performed optimization of the LUCX RF gun parameters to produce high-charge electron bunches keeping femtosecond bunch length. As a test of simulation results the experimental investigation of coherent transition radiation was carried out at KEK LUCX facility. [1] A. Aryshev, M. Shevelev, Y. Honda, N. Terunuma, and J. Urakawa, 2015 arXiv:1507.03302v1 [physics.acc-ph]} This work was supported by the Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sport, Science and Technology, Japan and JSPS KEKENHI: 23226020 and 2465076.

Speaker: Mr Mikhail Shevelev (KEK)

Slides shevelev_ch2016.pdf

182 Experimental Study of Coherent Smith-Purcell Radiation Monochromaticity

Intense THz radiation is extensively used for different applications including diffraction and spectroscopy [1, 2]. Modern approach to generate high power THz is based on ultra-short pulse compact accelerators [3, 4] or free-electron lasers [1]. However, an optimal mechanism for THz production is still under discussion. The aim of designing of a compact and tunable THz source with short pulse duration has to be reached with additional provision of radiation monochromaticity. In this respect a THz source based on Smith-Purcell radiation (SPR) mechanism appearing when a charged particle moves above and parallel to a grating is promising. In this report the investigation of the spectral characteristics of coherent Smith-Purcell Radiation (SPR) which was performed both theoretically and experimentally is presented. The measurement of SPR spectral line shapes of different diffraction orders was done at KEK LUCX facility. A pair of room-temperature Schottky barrier diode (SBD) detectors with sensitivity bands of 60 - 90 GHz and 320 - 460 GHz was used. A good match of experimental results and simulations performed with CST Studio Suite justifies the use of different narrow-band SBD detectors to investigate different order SPR spectral lines. It was shown that the monochromaticity of the SPR spectral lines increases with diffraction order. The comparison of coherent transition radiation and coherent SPR intensities in sub-THz frequency range showed that the brightness of both radiation mechanisms is comparable. A fine tuning of the SPR spectral lines is discussed.

Speaker: Dr Alexander Aryshev (KEK)

Slides aryshev_ch2016-inv.pdf

183 Coherent Grating Transition Radiation in sub-THz Wavelength Range

Grating transition radiation (GTR), which is a backward radiation, emitted by electrons interacting with a diffraction grating was first observed at optical wavelength region at 1999 [1]. In this report we present the experimental investigation of spectral and orientation dependences of a coherent GTR (CGTR) in sub-THz wavelength region emitted by a 8 MeV electron at KEK LUCX facility. The CGTR spectral line shapes up to 5-th diffraction order were measured for different inclination angles (theta=0-25 deg) with grating period 4 mm.

Speaker: Dr Gennady Naumenko (Tomsk Polytechnic University)

11:00 Coffee break

W2.2: The 8th AGTaX workshop “Advanced Generation of THz and X-ray beams

Convener: Dr Ivan Konoplev (JAI, Department of Physics, University of Oxford)

184 Periodic Structures Manufactured by 3D Printing for Electron Beam Excitation of Coherent Sub-Terahertz Radiation

For the creation of novel coherent sub-THz sources excited by electron beams there is a requirement to manufacture intricate periodic structures to produce and radiate electromagnetic fields. Additive manufacturing [1], or “3D printing”, is promising to be quick and cost-effective for prototyping these periodic structures. Such structures are of great interest because the application of smart dispersion designs is having a positive impact on research leading to improved high-power coherent mm-wave sources [2-4]. Two dimensional (2D) periodic surface lattices (PSLs) [5] can be created by manufacturing shallow periodic perturbations on the inner surface of a hollow electrically conducting cylinder. The cylindrical PSL structures need to be compatible with vacuum conditions and the use of energetic electron beams, while also providing the required boundary conditions for the electromagnetic fields. Manufacturing the cylindrical PSLs out of a suitable metal usually provides a good vacuum envelope and the good electrical conductivity allows conduction away of any electrical charges impacting on the surfaces. A good thermal conductivity coefficient is another property that metals tend to possess and is helpful for PSLs intended for use in high power sources. These 2D PSLs can be used for several applications that exploit a variety of physical phenomena, [2-8]. A dispersion relation describing the coupling of the volume and surface fields inside a 2D PSL of cylindrical topology was derived by Konoplev et al. [7]. Under certain conditions, when driven by a suitable electron beam this structure can support a Cherenkov instability that provides a coherent source of electromagnetic radiation. Periodic structures in cylindrical geometry have been successfully prototyped using 3D printing to create a primary mold, which has then been used to cast successfully a metallic cylindrical PSL to form the interaction cavity for a novel sub-THz source. The 3D printing technology used has reasonably high resolution and the dimensional errors achievable with 3D printing are projected to decrease over time as the technology develops. Measurements, made using a vector network analyser, of the electromagnetic properties of a cylindrical PSL manufactured by these methods are compared with simulations made using CST Microwave Studio. References 1. I. Gibson, D. Rosen and B. Stucker, “Additive Manufacturing Technologies: 3D Printing, Rapid Prototyping, and Direct Digital Manufacturing”, 2nd Edition, (2015) Springer, New York, USA. 2. N.S. Ginzburg, N.Yu. Peskov, A.S Sergeev, et al., J. Appl. Phys., 92 (2002) 1619-1629. 3. N.S. Ginzburg, N.Yu. Peskov, A.S Sergeev, et al, Phys. Plasmas, 9 (2002) 2798-2802. 4. I.V. Konoplev, A.W. Cross, A.D.R. Phelps, et al., Phys. Rev. E, 76 (2007) 056406. 5. I.V. Konoplev, L. Fisher, A.W. Cross, et al., Appl. Phys. Lett., 96 (2010) 261101. 6. A.W. Cross, I.V. Konoplev, A.D.R. Phelps, et al., J. Appl. Phys., 93 (2003) 2208-2218. 7. I.V. Konoplev, A.J. MacLachlan, C.W. Robertson, et al., Appl. Phys. Lett.,101 (2012) 121111. 8. I.V. Konoplev, A.J. MacLachlan, C.W. Robertson, et al., Phys. Rev. A, 84 (2011) 013826.

Speaker: Prof. Alan Phelps (Department of Physics, University of Strathclyde, Glasgow G4 0NG, UK)

Slides phelps_ch2016-inv.pdf

185 Tunable High-peak-current electron bunch train and its application in THz production

High peak current electron bunch trains can find applications in high transformer ratio wakefield acceleration and high power tunable narrow band THz production. Based on the TTX (Tsinghua Thomson-scattering X-ray) facility, we performed experiments on high peak current bunch train production by nonlinear longitudinal space charge oscillation and obtained narrow band THz radiation via coherent transition radiation(CTR) with such bunch trains. The THz radiation spectrum was able to be conveniently tuned both by chicane strength and the gun phase. The radiation power was maximized by optimizing the longitudinal modulation on the drive laser.

Speaker: Dr Lixin Yan (Department of Engineering Physics, Tsinghua University)

Slides yan_ch2016.pdf

186 Recently research progress on Thomson scattering X-ray source at Tsinghua University

Tsinghua Thomson Scattering X-ray Source (TTX) is the first-of-its-kind dedicated hard X-ray source in China based on the Thomson scattering between a terawatt ultrashort laser and relativistic electron beams [1]. Many improvements have been performed at the facility during the last three years since 2013, including developing a new separated Ti:Sapphire laser system for collision, 100-fs timing system, photocathode RF gun to produce better electron beams and many beam diagnostic methods. The measured photon yield at ~50keV is 2×〖10〗^7 per pulse, which is increased by an order compared with the previous report [1]. The angular intensity distribution and energy spectra of the scattered X-rays are measured by the silicon attenuators and Bragger diffraction in Highly Oriented Pyrolytic Graphite(HOPG) crystal. The results of the two methods are both agrees well with the theory predictions. The scattered x-rays are partial coherent, due to the very small beam size(~5μm, theoretical value), which meets the requirement of phase contrast imaging(PCI). A series of samples like shrimp, fish, and peanut are imaged using TTX, and both absorption image and phase contrast images at different imaging distances of the same sample are taken. The interfaces between different materials in the samples are enhanced as the imaging distance increases. Because of this characteristic the testa of peanut, which can’t be distinguished from cotyledon under its absorption image, can be seen clearly under its phase-contrast image, making interfaces diagnostic of low-Z materials possible. Besides, the tomography technique is also performed with the generated X-rays, and the 3-dimension structure of peanut are reconstructed. [1] Yingchao Du, Lixin Yan, Jianfei Hua, Qiang Du, Zhen Zhang, Renkai Li, Houjun Qian, Wenhui Huang, Huaibi Chen, and Chuanxiang Tang. "Generation of first hard X-ray pulse at Tsinghua Thomson Scattering X-ray Source." Review of Scientific Instruments 84, no. 5 (2013): 053301.

Speaker: Dr Yingchao Du (Tsinghua University)

Slides du_ch2016.pdf

187 Investigation of super-radiant Smith-Purcell radiation from double grating and DC beam

Generation of intense THz radiation beams is important for a growing demand in research based on THz spectroscopy and imaging. Physical processes associated with the beam propagation near a grating or a system of gratings give rise to beam energy modulation as well as radiation emission based on the mechanism of Smith-Purcell radiation, with the capability to tune both processes. Devices that contain compact, periodic structure, operate in a continuous wave mode and allow to produce moderate levels of average output power have been the subjects of extensive research from the perspectives of analytical studies, electromagnetic simulations, and experiments. The purpose of this report is to investigate both of these processes using Particle In Cell simulations. We discuss characteristics of the SPR emitted from such double grating system, including spectral response and dependence of the radiation power on the beam current. We also investigate conditions that have to be fulfilled for beam modulation and efficient radiation emission to occur.

Speakers: Dr Konstantin Lekomtsev (Royal Holloway University of London), Dr Pavel Karataev (Royal Holloway, Unviersity of London)

Channeling 2016 Closing

Convener: Sultan Dabagov (LNF)

13:05 Lunch

W2.3: The 8th AGTaX workshop “Advanced Generation of THz and X-ray beams

Convener: Dr Wolfgang Wagner (HZDR Dresden)

188 Status of the development of Delhi Light Source (DLS) at IUAC

The demand of the Terahertz radiation in various fundamental and applied research fields is increasing steadily. To address the requirement, a project to construct a compact Free Electron Laser by using a normal conducting photocathode electron gun has been conceived at Inter University Accelerator Centre (IUAC), New Delhi, India [1, 2]. In this facility, a single laser pulse will be split in to many micro-pulses which will produce a ‘comb beam’ of electrons [3, 4] from metal as well as from semiconductor photocathodes. The electrons produced from the photocathode will be accelerated up to an energy of ~8 MeV by a copper cavity operated at a frequency of 2860 MHz whose design is similar to those at BNL and KEK [5,6]. The resonance frequency of the copper cavity was chosen as 2860 MHz since the gun is planned to be replaced later by a superconducting photoinjector working at a multiple of 130 MHz. The separation of the laser micro-pulses will be varied by adjusting path length difference of the interferometer-type pulse divider and thus the separation of the electron microbunches will be also altered. For every separation of the electron microbunches, the magnetic field of the undulator and/or the electron energy will be adjusted in such a way, that the THz radiation can be tuned in the range of ~ 0.15 to 2.5 THz. The 2.6 cell, 2860 MHz copper cavity to be used as electron gun has been fabricated, tested and waiting to be installed in the beam line. Other components like the Klystron/Modulator, the photocathode deposition mechanism, the laser system, the undulator magnet, various electromagnets, beam line components, etc. are being procured or under advanced stage of design. Production of the electron beam and the THz radiation from Delhi Light Source is expected to be demonstrated by the year 2017 and 2018, respectively. In this report the principle of generation of ‘comb’ beam, expected characteristics of super-radiant undulator radiation, the possible experiment by the radiation, etc. will be presented. References 1. S. Ghosh et al., Proc. of FEL2014, Basel, Switzerland, p. 596. 2. S.Ghosh et al., Proc of IPAC 2016, Busan, Korea. 3. M. Boscolo et al., NIM A 577 (2007), page 409-416. 4. A. Aryshev, M. Shevelev, Y. Honda, N. Terunuma, and J. Urakawa, 2015 arXiv:1507.03302v1 [physics.acc-ph] 5. X. J. Wang et al., Nucl. Instrum. Meth. A356, 1995, p. 159. 6. A. Deshpande et al., Phy. Rev. Special Topic Accel. Beams, 14, 2011, 063501.

Speaker: Dr Subhendu Ghosh (Inter University Accelerator Centre)

Slides ghosh_ch2016.pdf

189 Concept of tunable, high power source of coherent THz radiation

Tunable, source of coherent THz radiation driven by pre-bunched electron beam is discussed. We consider the generation of the multi-bunch train by using either self-modulation instability in a plasma channel or radiating a photocathode with a train of femtosecond laser pulses. By changing the plasma density in the channel or distance between the laser pulses, variation of the bunch train modulation frequency can be controlled. Using the multi-bunched beam, frequency-tunable coherent THz radiation can be generated if the beam propagates above high-impedance surface and study of THz radiation generation when modulated beam propagates above the periodic shallow grating is presented.

Speaker: Dr Ivan Konoplev (JAI, Department of Physics, University of Oxford)

Slides konoplev_ch2016.pdf

190 Angular distribution of coherent Cherenkov radiation from a tilted bunch passing through a slit in target

We considered coherent Cherenkov radiation (CChR) produced by a tilted bunch passing through a slit in a dielectric slab. For a chosen dielectric susceptibility ε=1.3 the resulting CChR propagates from a target bulk to vacuum at the angle θch=32.6˚. The azimuthal asymmetry in CChR angular distribution was calculated and shown that difference of yields for azimuthal angles φ=0˚ and φ=180˚ is enhanced two orders of magnitude. The maximal CChR intensity yield at the angle θch is achieved for the same value of the bunch tilt angle.

Speaker: Prof. Alexander Potylitsyn (Tomsk Polytechnic University)

Slides potylitsyn_ch2016-2.pdf

191 Cherenkov Diffraction radiation from long dielectric material: An intense source of photons in the NIR-THz range

Unlike Synchrotron Radiation, which is naturally emitted as particles are deflected in undulators, wigglers or bending magnets, Diffraction Radiation (DR) [1] is produced as charged particles pass in the close vicinity of a dielectric or a metal. For highly relativistic particles, diffraction radiation can produce non-negligible amount of photons in standard beam conditions. DR from slits and holes has been investigated during the last 15 years for beam diagnostics as non-interceptive beam size monitors [2, 3]. An experimental set-up has been developed and used already for some years on the Cornell storage ring using 2.1 GeV electrons. With a 1mm aperture slit, the radiated power becomes high enough for beam diagnostic purposes [4] but remains low enough to be considered for others applications. We are currently preparing a test to produce incoherent Cherenkov Diffraction Radiation (CHDR) in the near infrared spectral range from a 1cm long fused silica crystal. In such conditions the light output power would be significantly large compared to the typical diffraction radiation power emitted from a slit of similar aperture. The target design and the detection set-up are presented in detail with simulations describing the expected properties of the emitted Cherenkov diffraction radiation, in terms of light intensity and spectral bandwidth. Finally, potential applications of CHDR are discussed [1] A. P. Potylitsyn et al., “Diffraction Radiation from Relativistic Particles”, (Springer, Berlin Heidelberg, 2010) [2] P. Karataev, et al. “Beam-size measurement with Optical Diffraction Radiation at KEK Accelerator Test Facility”, Phys. Rev. Lett. 93, 244802 (2004) [3] A. Cianchi, M. Castellano, L. Catani, E. Chiadroni, K. Honkavaara, and G. Kube, "Nonintercepting electron beam size monitor using optical diffraction radiation interference", Phys. Rev. ST Accel. Beams 14, 102803 (2011) [4] L. Bobb, T. Aumeyr, P. Karataev, E. Bravin, T. Lefevre, S. Mazzoni, H. Schmickler, M. Billing, J. Conway, "Vertical Beam Size Measurement at CESRTA Using Diffraction Radiation", IBIC 2014: Proceedings of the 3rd International Beam Instrumentation Conference, Monterey, CA, 2014

Speaker: Dr Thibaut Lefevre (cern)

Slides lefevre_ch2016.pdf

192 Smith-Purcell radiation from a ribbon beam as effective THz source

Electrons moving above a periodic dielectric structure generate Smith-Purcell radiation (SPR). SPR may serve for noninvasive bunch diagnostics and also as a good source of THz radiation [1, 2]. In the present report we suggest using a ribbon beam in order to enhance the effective interaction between the beam and grating. In our previous works [3,4] we used the scheme with cylindrical symmetry, whereas here we construct the theory of SPR for the flat beam and flat grating from the first principles, calculate spectral and angular distributions of radiation, and analyze the radiation characteristics in THz range for the parameters of LUCX (KEK). References 1. A.P. Potylitsyn, M. I. Ryazanov, M.N. Strikhanov and A.A. Tishchenko, Diffraction radiation of relativistic particles, Springer, 2011. 2. S. E. Korbly et al., Observation of frequency locked coherent Terahertz Smith-Purcell radiation, PRL 94, 054803 (2005). 3. A.A. Ponomarenko, M.I. Ryazanov, M.N. Strikhanov, A.A. Tishchenko, Terahertz Radiation from Electrons Moving through a Waveguide with Variable Radius, Based on Smith-Purcell and Cherenkov Mechanisms, Nucl. Instrum. and Meth. B 309, 223 (2013). 4. A.A. Ponomarenko, K.V. Lekomtsev, A.A. Tishchenko, M.N. Strikhanov, J. Urakawa, CST simulation of THz radiation from a channel with periodically variable radius, Nucl. Instr. and Meth. B 355, 160-163 (2015).

Speaker: Dr Alexey Tishchenko (National Research Nuclear University "MEPhI")

193 Optical diffraction radiation experiment at KEK-ATF2

For future high current linear lepton machines, non-invasive beam size measurement systems based on Optical Diffraction Radiation (ODR) have been the subject of extensive research in the past years. We report here the installation and commissioning of a high resolution Optical Diffraction Radiation (ODR) experiment on the KEK-ATF2 electron beam-line in Tsukuba (JP). The experimental apparatus allows the observation of both transition radiation (OTR) and diffraction radiation (ODR). The aim is to develop beam size and beam position measurement systems that combines sub-micron resolution OTR for single bunch operation, and non-invasive ODR for full intensity beams with a typical resolution of 15 microns or better. The setup being very versatile with a set of target slits and mask slits covering widths from 50 to 400 microns, multiple aspects of the ODR physics can be studied through a systematic study of the parameters (eg. target/mask size combination, ODR wavelength and polarisation etc.) to achieve the best beam-size sensitivity. The set of masks is positioned a few centimetres upstream the target to reduce the unwanted synchrotron radiation contribution generated by the ATF2 magnets. The mask also acts as a second source of light (forward ODR) and leads to the creation of an interference pattern together with the target signal (backward ODR) [2]. The beam size measurement is performed using the visibility of the angular interference pattern recorded in the far field region, while the observation of the target in imaging conditions can be used as a beam position monitor. The very first results of this ODR/OTR experiment will be presented by the author. References [1] P. Karataev et al., "Application of optical diffraction radiation to a non-invasive low-emittance high-brightness beam diagnostics” In Hiroshima 2003, Quantum aspects of beam physics 111-118. [2] A. Cianchi, M. Castellano, L. Catani, E. Chiadroni, K. Honkavaara, and G. Kube "Non-intercepting electron beam size monitor using optical diffraction radiation interference" Phys. Rev. ST Accel. Beams 14, 102803 Published 28 October 2011.

Speaker: Dr Robert Kieffer (CERN)

Slides kieffer_ch2016.pdf

194 Generation of Plasmons with quantum charged fast oriented particle

The theory of the generation of the single-particle and collective excitations in a crystal by a fast charged quantum oriented relative to the crystallographic axes particle is constructed. The dependence of the intensity of the generation of excitations in the crystal depending on the level of the transversal both sub barrier and over barrier movement is obtained. It is shown that the loss of transverse energy by the fast quantum charged particle moving in the potential of the curved crystal is leading to the effect of the volume capture of such particles in the crystal. Mathematical modeling of the various modes both of the volume capture and volume reflection of fast charged particles in a bent crystal is carried out.

Speaker: Prof. Nikolay Kudryashov (National Research Nuclear University “MEPHI”)

Slides kudryashov-mazur_ch2016.pdf

16:30 Coffee break

W2.4: The 8th AGTaX workshop “Advanced Generation of THz and X-ray beams

Announcements / Discussions / Closing

Convener: Dr Alexander Aryshev (KEK)