1st European Advanced Accelerator Concepts Workshop

2 Jun 2013, 17:00 → 7 Jun 2013, 19:00 Europe/Rome

La Biodola, Isola d'Elba

Massimo Ferrario (LNF)

The European Advanced Accelerator Concepts Workshop has the mission to discuss and foster methods of beam acceleration with gradients beyond state of the art in operational facilities. The most cost effective and compact methods for generating high energy particle beams shall be reviewed and assessed. This includes diagnostics methods, timing technology, special need for injectors, beam matching, beam dynamics with advanced accelerators and development of adequate simulations.
This workshop is organized in the context of the EU-funded European Network for Novel Accelerators (EuroNNAc), that includes 52 Research Institutes and universities.

The EAAC will be followed by a 1-day EuroNNAC network meeting by invitation only.
 

The Workshop proceedings are now available on-line:
NIM-A, Vol 740

EAAC2013 scope:

• High gradient and multibunch acceleration in metallic structures (C-X-band and beyond) with innovative power generation schemes
• Plasma accelerators driven by modern lasers
• Plasma accelerators driven by electron beams
• Plasma accelerators driven by proton beams
• Dielectric structures and other novel technologies
• Novel schemes using advanced technologies (table-top FEL, plasma linear collider, ...)
• Computations for Accelerator Physics Advanced beam diagnostics for beams and plasma

The Registration fee is 400,00 €.

Sunday, 2 June

17:00 → 19:30 Opening of the Registration

19:30 → 20:30 Welcome Cocktail

Monday, 3 June

08:30 → 10:30 Plenary 1

Convener: Prof. Andrei Seryi (John Adams Institute for Accelerator Science)

08:30 Welcome

Speaker: Massimo Ferrario (LNF)

08:40 The Future is Fiber Accelerators

The challenge of producing the next generation of particle accelerators for scientific and societal applications, has been taken up by the High-intensity Community. One of the main standing issues for creating laser-based accelerators to match or better the performance of traditional accelerators is the requirement that the drive lasers produce simultaneously high peak and high average power with high efficiency>30%. . Even state of the art petawatt lasers typically have average powers of only a few tens of watts with a wall plug efficiency of 10-4. These are pitiful considering that real accelerators will require pulse repetition rates much higher – tens of kHz – and average laser powers of hundreds of kW with wall plug efficiency >30%. The international Coherent Amplification Network (ICAN) has shown[1] that a novel laser architecture based on a massive array of fibre lasers could be a cost effective solution. In addition to high peak and average powers, excellent efficiency it offers the potential of perfect and digitally controllable beam quality. [1] Gerard Mourou, Bill Brocklesby, Toshiki Tajima, and Jens Limpert, The future is Fiber Accelerators, Nature Photonics, Vol.7, 258-261 (213)

Speaker: Prof. GERARD MOUROU (ECOLE POLYTECHNIQUE)

Slides mourou.pdf

09:20 Frontiers of Dielectric Laser Acceleration

Speaker: Prof. James Rosenzweig (UCLA)

Slides ROSENZWEIG.pptx

10:00 The European Perspective of Accelerator Research

The EU support to the R&D on particle accelerators has been steadily increasing in the last 10 years, reaching about 6 MEUR/year in 2012/13. Among the reasons for this success are the good organisation of the community, the largely multidisciplinary scientific base, the healthy equilibrium between large laboratories and small universities, and the increasing impact of accelerators beyond basic science. The projects have usually a 4-year duration which allows an adaptation to the evolving scientific priorities; we are presently in the transition phase between the two generic accelerator R&D projects EuCARD and EuCARD-2, with EuCARD-2 including for the first time an important part on plasma-based acceleration. While EuCARD-2 will last until 2017, preparation is already starting for projects to be funded within the new Horizon-2020 EU program that starts in 2014 and aims at increasing the impact of basic science on the whole society.

Speaker: maurizio vretenar (cern)

Slides Vretenar.pptx

10:30 → 11:00 coffee break

11:00 → 12:40 Plenary 2

Convener: Dr Ralph Assmann (DESY)

11:00 Story of Laser Plasma Accelerators

Since the first idea to use intense laser pulse to generate collective electron motion suitable for electrons acceleration, many new ideas have been proposed and have been successfully demonstrated. The tremendous progresses that have been done over the world these recent years show the vitality of a new and growing community at the interface of accelerator, plasma and laser sciences. These accelerators based on laser plasma cavities have the particularity to support very intense electric field, with values of the order of hundreds of GV/m that can be used to deliver high quality electron beam with unique parameters. This alternative approach, rich in very exciting physical phenomena, opens the route for many applications. I'll tell you in this presentation the fascinating history of laser plasma accelerators.

Speaker: Prof. Victor Malka (LOA)

Slides EAAC_Malka.pdf

11:40 Overview of Advanced Compton Sources

Three physical regimes of Compton Sources based on back-scattering of high power lasers by relativistic high brightness electron beams will be discussed. Electron recoil is the key quantity: X-ray Thomson sources are characterized by negligible recoil and can be described classically as synchrotron radiation sources. Compton sources for nuclear photonics are characterized by a small electron recoil. However, their spectral properties are not significantly affected, so that a classical description is still accurate, as far as the recoil red-shift is taken into account as an average spectrum shift. Gamma-gamma colliders operate in the third regime, where Klein-Nishina formalism must be applied to describe the decrease of total cross section. The electron beam is weakly perturbed in the Thomson regime, where energy loss is comparable to beam energy spread. There is instead a significant distortion of the beam phase space in the intermediate regime of Gamma-ray Compton sources: the electron energy distribution goes through a transitory production of fringes, but eventually can be described by a Chapman-Kolmogorov master-equation, bringing to complete diffusion. Different technologies applied in new generation Compton sources, aiming at producing photon beams with very high brilliance, will be summarized.

Speaker: Luca Serafini (MI)

Slides Serafini-EAAC-2013-public.ppt

12:10 High-Brightness High-Duty Cycle Electron Injectors.

High brightness electron sources have been one of the driving forces (probably the main) behind the spectacular results achieved in the last decade by some accelerator-based applications. Indeed, x-Ray FELs, with their 10-fold order of magnitude increase in peak brightness, probably represent the best example of it. New ambitious proposals for x-ray FELs and ERLs, as well as inverse Compton sources for x-ray or gamma ray production, are now requiring operation at MHz-GHz repetition rates. In response to that, a number of groups around the world have been actively working in developing high-brightness high-duty cycle electron injectors capable of driving such machines. The high repetition rate requirement cannot be met by the existing low-repetition rate high-brightness injector schemes, and new technologies and configurations are under investigation. This presentation includes a description of the requirements for such injectors, an overview of the pursued technologies and schemes, a description of the main beam dynamics issues associated with this regime of operation, and examples of the results obtained so far by the groups active in the field.

Speaker: Fernando Sannibale (Lawrence Berkeley National Laboratory)

Slides Sannibale.pdf

12:40 → 15:00 Lunch

15:00 → 17:00 WG1 - Electron beams from plasmas

Conveners: Prof. Patric Muggli (Max-Planck-Institut für Physik), Prof. Zulfikar Najmudin (Imperial College London)

15:00 Experiments on laser plasma acceleration driven in longitudinally-profiled plasmas

W.Rittershofer, N.Bourgeois, J.Cowley, C.Thornton, S.M.Hooker University of Oxford T.Kleinwächter, C.Palmer, J.Osterhoff Deutsches Elektronen Synchrotron, DESY L.Schaper Deutsches Elektronen Synchrotron, DESY Universität Hamburg M.Hansson, L.Senje, M.Burza, A.Persson, O.Lundh, C.-G.Wahlström Lund University S.Chou, K.Krennikov, A.Popp, S.Karsch Max Planck Institute for Quantum Optics D.R.Symes, P.P.Rajeev, S.J.Hawkes, O.Chekhlov, C.J.Hooker, B.Parry, Y.Tang Rutherford Appleton Laboratory Techniques for increasing the energy gain per stage of laser-driven plasma accelerators are of great interest. One way of achieving this is to control the dephasing of a beam with respect to a plasma wave driven by a short-pulse laser by applying tapered plasma channels or longitudinal plasma density variations. We present the results of experiments at the Lund Laser Centre, Sweden and at the Rutherford Appleton Laboratory, UK on laser plasma acceleration driven in longitudinally-profiled plasmas. The energy, pointing stability and divergence of the electron beams generated in these plasma targets will be described. Measurements of the x-ray spectrum from betatron motion of the electron bunch will also be reported.

Speaker: Mr Wolf rittershofer (university of oxford)

15:15 Stable and tunable laser-wakefield acceleration and x-ray generation

We report on several experimental campaigns on laser-wakefield electron acceleration and radiation generation from laser-driven free electrons. Using a 60 TW-Ti:Sapphire laser, we routinely obtain stable electron beams with energies of up to 0.5 GeV, beam charge of 30-300 pC and bunch durations around 5fs. After passing a miniature undulator, a first all-laser driven X-ray undulator source with photon energies in the water window (300eV) could be demonstrated. Furthermore, the betatron emission from the wiggling motion of the electrons in the plasma wave was characterized, revealing 10^8 photons/shot with typical mean photon energies of 5 keV from a 2 µm source and 10 mrad divergence. This photon beam was used to obtain the first 3-D phase-contrast tomogram of a fly from a laser-driven free-electron source. Finally, we will report on the first tunable, quasi-monochromatic Thomson X-ray source in the energy range from 5 to 35 keV, obtained by colliding tunable 15-50 MeV electron beams off a short laser pulse.

Speaker: Prof. Stefan Karsch (LMU Munich)

15:30 Advanced Reproduction of Space Radiation Studies by overdense laser plasma interaction

Ionizing radiation in planetary orbits as in Earth’s Van Allen belt or the Jovian magnetospheres is a significant hazard for electronically and optical components aboard spacecraft’s. Hence a not negligible amount of time and expenses is spent for testing all radiation sensitive components before a mission. This opens a novel field for LPAs which makes use of the inherent ability of LPAs to generate broadband radiation. The spectral distribution of radiation belt electrons is exponentially-/power law-shaped, in contrast to monoenergetic distributions provided by conventional accelerators. In the completed proof-of-principle experiment with a 30 µm solid Al-target effective electron temperatures < 1 MeV were generated, which is very similar to Earth’s radiation belt environment. We investigated the intensity dependence of the electron temperature and the spatial distribution of emission. Due to the high electron flux the daily dose of 3e12 electron/cm2 in a typical navigation satellite orbit can be reached within 140 seconds, instead of several hours needed with today’s state-of-the-art testing techniques. We present an application of enormous industrial relevance including the setup and the results of our experiment, as well as numerical results from PIC simulations.

Speaker: Mr Oliver Karger (University of Hamburg, Institute for Experimental Physics)

Slides EAAC-Elba-2013-SpaceRadLPA-OK-v1-WGSummary-withoutResults.pdf

15:45 Hybrid Laser-Plasma-Wakefield Acceleration

Electron beams from laser-plasma-accelerators often have rather large energy spreads and only limited reproducilibility, which can be a showstopper for many key applications. Nevertheless, they have parameters which indicate that they are highly suited as electron bunch drivers in plasma wakefield acceleration afterburner stages. For example, large energy spreads do not at all decrease their ability to drive strong plasma waves. Hybrid concepts involving multiple electron bunches [1] and highest-quality bunches generated inside the second plasma stage [2] (also known as Trojan Horse plasma wakefield acceleration), as well as hybrid scenarios where electron bunches from conventional accelerator stages are used as drivers have been developed. Here we discuss the potential of such hybrid systems for a dramatic improvement of electron beam stability and quality, which may allow to build free-electron-lasers which are ultracompact yet have better unprecedented performance, and the experimental advances in the field. [1] Phys. Rev. Lett. 104, 195002 (2010) [2] Ultracold Electron Bunch Generation via Plasma Photocathode Emission and Acceleration in a Beam-driven Plasma Blowout, Phys. Rev. Lett. 108, 035001 (2012) [3] Hybrid modeling of relativistic underdense plasma photocathode injectors, Y. Xi, et al., PRSTAB 031303 (2013)

Speaker: Prof. Bernhard Hidding (Uni Hamburg/DESY/UCLA)

16:00 Ultra-short electron bunches by Velocity Bunching as required for plasma wave acceleration

The generation of ultra-short bunches is nowadays a critical requirement for plasma wave accelerators, on which many laboratories world-wide are investigating or close to start with experimental activities. This requirement is true for both, external injection into Laser Wake Field Accelerators, where injected beams need lengths close or shorter than 10 fs, or Plasma Wake Field Accelerations (PWFA), where the wake field intensity scales like the driver bunch charge over the square of the rms bunch length (Q_b/σ_z^2). This work presents beam dynamics simulations, which show how to use the Velocity Bunching (VB) technique to obtain such ultra-short bunches. The VB is applied with a proper control of the bunch density versus the energy gain, which permits to control the transverse normalized emittace as well as the correlated longitudinal energy spread, using small bunch charges (1-10pc). Our optimization is carried out taking the SPARC's Linac layout, which has been designed to maximize the VB performances.

Speaker: Alberto Luigi Bacci (MI)

Slides ABacci_EAAC2013.pptx

16:15 Laser wakefield acceleration experiments at the University of Michigan

Laser Wakefield Acceleration experiments using the HERCULES laser system operating up to 200 TW at the University of Michigan will be described. High energy electron beams (up to 800 MeV) were produced along with energetic positrons, neutrons, gamma rays and spatially coherent x-rays using both gas jets and gas cells as targets. The measurement of scattered Raman radiation as a diagnostic of the propagation as well as a diagnostic of the process of electron injection into the wakefield will also be discussed.

Speaker: Prof. Karl Krushelnick (University of Michigan/Laboratoire d'Optique Appliquee)

16:30 Status and plans of laser-plasma acceleration research in IAP RAS

Laser-plasma acceleration has been experimentally studied at PEARL facility. Plasma wakefields excited by low-power laser have been observed in gas-filled capillary tube. Important theoretical results have been obtained and efficient numerical codes have been developed. PEARL-10 is under construction. It will provide power up to 5 PW. The work is supported by Ministry of Science and Education of Russian Federation.

Speaker: Dr Kostyukov Igor (Institute of Applied Physics RAS, Nizhny Novgorod State University)

15:00 → 17:20 WG3 - Electron beams from electromagnetic structures, including dielectric and laser-driven

Convener: Prof. James Rosenzweig (UCLA)

15:00 2D Theory of Wake-Field Amplification by Active Medium

A train of micro-bunches generates in a passive dielectric loaded waveguide an electro-magnetic wake which propagates at the speed of the particles. This wake consists of propagating modes provided the electrons exceed the Cerenkov velocity. If the material is replaced with an active dielectric, identical to that of a laser, the wake is amplified. Another train of bunches, lagging many wavelengths behind, may be accelerated by this amplified wake. The gradient is limited by breakdown and saturation of the medium. Beam loading may be partially or even completely compensated by the gain along the trailing bunch. Preliminary results of a linear theory will be presented, assuming a 300MeV beam and high-pressure CO2 mixture as an active medium. In spite many hundreds of modes excited by the front beam, the spectrum of the amplified field corresponds to a monochromatic wave determined primarily by the bandwidth of the medium. The analytic approach facilitates simple assessment of the effect of the various parameters on the accelerating gradient.

Speaker: Prof. Levi Schachter (Technion - Israel Institute of Technology)

15:20 Fibre Laser Based Dielectric Gratings Accelerator

Dielectric laser accelerators (DLA) have great potential for applications, since they can generate acceleration gradients in the range of GeV/m and produce attosecond electron bunches. We numerically investigated the optimum structure dimensions of a dual-gratings accelerator structure made of silicon, the standard material for photolithography fabrication process and compare the accelerating efficiency for the case of asymmetric and symmetric distribution of dielectric and vacuum space. We analytically estimated the laser requirements and propose a suitable power source. Finally, we proposed a new scheme for better beam confinement. The codes CST Microwave Studio and Particle Studio are used for simulations and benchmarked against the VORPAL code.

Speaker: Mr Aimidula Aimierding (Cockcroft Institute and The University of Liverpool, UK)

15:45 Dielectric laser acceleration of 28 keV electrons with the inverse Smith-Purcell effect

Dielectric laser acceleration exploiting the large optical field strength of short laser pulses and the proximity of a dielectric structure can support high acceleration gradients and may therefore lead to much smaller accelerators, with future potential application in table-top free electron lasers. We report a proof-of-concept experiment demonstrating dielectric laser acceleration of non-relativistic 28keV electrons derived from a conventional scanning electron microscope column at a single fused-silica grating. The electrons pass the grating as closely as 50nm and interact with the third spatial harmonic, which is excited by 110fs long 800nm laser pulses with a peak electric field of 2.85GV/m. The observed maximum acceleration gradient of 25MeV/m is already comparable to state-of-the-art radio-frequency structures. This work represents the first demonstration of scalable laser acceleration and of the inverse Smith-Purcell effect in the optical regime. For relativistic electrons and otherwise identical conditions up to 2 orders of magnitude larger acceleration gradients are expected.

Speaker: Prof. Peter Hommelhoff (University of Erlangen and Max Planck Institute of Quantum Optics)

16:10 Helical Accelerating Structure with Controllable Beam Emittance

A new helical RF accelerating structure, which can provide emittance control of the electron beam, is proposed. This structure combines properties of a linear accelerator and a damping ring simultaneously. It makes acceleration of straight on-axis beam as well as beam cooling due to the synchrotron radiation of particles. These properties are provided by specific slow eigen mode which consists of two partial waves, TM01 and TM11 (near to cut off). The longitudinal field of the first wave is synchronous with electrons, the transverse fields of the second wave are far from synchronous condition and they cause electron wiggling like it occurs in RF undulator. As a result the emittance control might be employed at linear trajectory of the high-energy beam without decrease of the average gradient. Calculations show that surface electric field at level ~0,31 (relative to accelerating field) and shunt impedance ~20 MOhm/m at 30 GHz are achievable. Cooling rate at gradient 100 MV/m corresponds to the equivalent magnetic field ~0,75 T. Additional appealing properties are beam focusing by ponderomotive force, the shape does not contain neither narrowing nor widening, the mass production seems possible without brazing of short segments.

Speaker: Dr Sergey Kuzikov (Institute of Applied Physics, Russian Academy of Sciences)

Slides Helical_acc_str.pptx

16:30 Towards a full C-band multi-bunch/high rep. rate/high gradient injector linac

The use of RF C-Band accelerating structures for electron acceleration and production of high quality beams has been recently proposed and adopted in several linac project all over the world. The current projects foreseen the use of an S-band injector combined with a C-band linac booster. C-band accelerating cavities have been also proposed for the ELI-NP project and, because of the multi-bunch operation, the cavities integrate an HOM damping system. A full C-band injector that combines a C-band high rep. rate multi-bunch RF gun with C-band damped accelerating stucturess are the next and definitive step in the C-band systems. Beam dynamics simulations show excellent and feasible features. A complete design in term of single/multi bunch beam dynamics and RF system is presented.

Speaker: David Alesini (LNF)

Slides EAAC13_2013_Alesini.pptx

16:55 Bimodal Two-Frequency Half-Cell RF Gun

The concept of a Multi-Frequency Photoinjector (MUFFIN) is aimed the possibility of raising the breakdown threshold due to a reduction of surface exposure time to high fields, and due to the so-called anode-cathode effect. These properties help one to reach the desired beam energies (5-10 MeV) even in a two-frequency half-cell normal conducting cavity. Simulations that invoke standard transverse emittance compensating techniques were made for 1.3 GHz + 2.6 GHz MUFFIN to pro-vide electron bunches with parameters: 0.5-1 nC, 3-20 ps, frpt=1.3 GHz. Results show that one can produce bunches 1) 20 ps, 5 MeV (64 MV/m peak cathode-like surface electric field) with trans-verse emittance 2.5 mradmm consuming only 6.5 MW RF power, or optionally 2) 3 ps, 7.6 MeV (96 MV/m cathode-like field), 3 mradmm, 14.7 MW.

Speaker: Dr Sergey Kuzikov (Institute of Applied Physics, Russian Academy of Sciences)

Slides RF_gun.ppt

15:00 → 17:00 WG4 - Future accelerator concepts incl. gg, beam transport (applications)

Convener: Prof. Andrei Seryi (John Adams Institute for Accelerator Science)

15:00 Measurement of Nanometer Electron Beamsizes using Laser Interference by Shintake Monitor

One of ATF2’s major goals is to verify the Local Chromaticity Correction scheme by focusing the vertical e- beam size (σy ) down to its design 37 nm. Indispensable for this mission and for R&D of future linear colliders is the Shintake Monitor installed at ATF2’s virtual IP. It is the only existing beam size monitor capable of measuring σy < 100 nm. , The e- beam is collided against laser interference fringes, and σy is derived from the modulation depth of the resulting Compton scattered photons. A wide measurable range from 20 nm to a few μm, is enabled by switching between several laser crossing angle modes. σy < 150 nm have been achieved by Feb, 2012. Major upgrades in the laser optics suppressed various systematic errors and signal jitters, improved resolution, and led to remarkably stable contribution during continuous ATF2 beam runs in 2012 winter, during which the smallest σy ever of about 70 nm had been confirmed. This record was renewed in spring 2013 to stable measurements ofσy < 60 nm. Further hardware upgrades and dedicated error studies are ongoing to realize focusing and stable measurement of σy < 50 nm.

Speaker: Ms Jacqueline Yan (University of Tokyo, School of Science)

Slides 130603-EAAC2013.pdf 130603-EAAC2013.ppt

15:30 High quality proton beams from laser plasma interaction with hybrid acceleration schemes

The quality of laser accelerated proton beams is still low and hybrid schemes are a possible alternative for near term applications. We achieve energy and angle selection with a transport line wihich renders the beam suitable post-acceleration. We show that with a pulse of intensity I ~ 10^21 W/cm^2 proton energies above 40 MeV are obtained from 3D PIC simulations as in the KPSI experiment. Various targets are considered and increasing the intensity up to I ~ 2 10^21 W/cm2 the number of protons in a 1 MeV slice at 30 MeV is at least 10^8 after selection by a pulsed solenoid and a collimator. We simulate the transport, injection into a compact linac and post-acceleration up to 60 MeV. The final protons number is decreased by one order of magnitude but the beam quality is excellent. A decrease by two orders of magnitude occurs if the selection is achieved by a multiplet of permanent magnetic quadrupoles. The charge, energy and final beam quality are at the threshold of interest for medical use.

Speaker: Mr Giorgio Turchetti (INFN)

Slides EAAC_Elba_Turchetti.ppt

17:30 → 18:00 coffee break

18:00 → 19:30 WG1 - Electron beams from plasmas

Conveners: Prof. Patric Muggli (Max-Planck-Institut für Physik), Prof. Zulfikar Najmudin (Imperial College London)

18:00 A Proposed Plasma Wakefield Acceleration Experiment Using CLARA Beam

A plasma wakefield acceleration experiment has been proposed to study the key issues in electron driven wakefield acceleration. A 250 MeV electron beam from the proposed FEL test facility so-called CLARA (Compact Linear Accelerator for Research and Applications) will get energy doubling with a ~ 20 cm plasma cell. In this talk, we will discuss the feasibility of electron beam transport and define the beam parameters for the possible experiments that can be conducted using CLARA beam. The detailed particle-in-cell simulations based on these parameters will be presented.

Speaker: Dr Guoxing Xia (Cockcroft Institute and the University of Manchester)

Slides CLARA_PARS.pdf

18:15 Preparations for a PWA experiment at PITZ

In light of the planned particle driven plasma wakefield acceleration experiment at CERN (AWAKE collaboration), particle beam self-modulation as proposed by Caldwell et al. has gained interest. Calculations and simulations show promising results but there is no direct experimental evidence yet. Therefore an effort was started at the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ), to set up an experiment to demonstrate and characterize self-modulation in electron beams. A lithium heat pipe oven is being developed as a plasma cell following the basic design of Muggli et al. Current features of the PITZ beam line which will be utilized for the experiment are amongst others the Max-Born Institute built photocathode laser system with a flexible temporal pulse shaper and the well-developed electron beam diagnostics. In this contribution the current status of preparing the self-modulation experiment at PITZ is summarized. Further on the efforts towards a planned experiment demonstrating plasma wakefield acceleration with high transformer ratio will be presented.

Speaker: Dr Matthias Gross (DESY)

Slides EAAC_workshop_June2013.pptx

18:30 Linear Plasma Wakefields and Seeding of the Self-modulation Instability

We have successfully demonstrated the driving of plasma wakefield by a square current profile electron bunch for the seeding for self-modulation instability (SMI) with 50pC bunches at the BNL-ATF. The experimental data is in excellent agreement with linear theory and OSIRIS-2D [1] simulation results [2]. Acquiring these results was possible because with low 50pC charge, the SMI does not grow within the 2cm propagation distance in the plasma. We explore here the possibility of identifying SMI growth experimentally with 1nC bunch by measuring the maximum energy gain/loss at plasma exit. According to linear theory, the initial wakefield amplitude is 20 times higher for a 1nC than than for a 50pC bunch, and this has been confirmed by the previous simulations [3]. Simulations also show that the SMI of the 1nC bunch grows significantly and reaches saturation over the 2cm propagation distance. Therefore, we further analyze the simulation results of 1nC bunch to examine the possibility of measuring the energy spectrum experimentally to confirm the development of SMI. Initial results show that due to dephasing between the bunch particles and the wakefields, the actual energy gain/loss by drive bunch particles is much lower than previously estimated.

Speaker: Prof. Patric Muggli (Max-Planck-Institut für Physik)

Slides SMItalkMuggliWG1.pdf

18:45 Feasibility Study of the AWAKE Facility at CERN

A Proton Driven Plasma Wakefield Acceleration Experiment has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof-of-principle demonstration experiment, AWAKE, is proposed using 400 GeV proton bunches from the SPS. Detailed studies on the identification of the best site for the installation of the AWAKE facility resulted in proposing the CNGS facility as best location. Design and integration layouts covering the beam line, the experimental area and all interfaces and services are shown. Among other issues, radiation protection, safety and civil engineering constraints are raised.

Speaker: Dr Edda Gschwendtner (CERN)

Slides EAAC13-AWAKE-Edda.pdf EAAC13-AWAKE-Edda.pptx

19:00 Electron injection into proton driven plasma wake-field for the AWAKE experiment at CERN

The AWAKE project at CERN is a proposed proof-of-principle experiment on the acceleration of electrons in a plasma wave excited by high-energy proton bunch. The 400 GeV proton bunch extracted from the SPS accelerator will pass through 10 m long plasma section. Plasma will be produced from Rb gas via photo-ionization by short laser pulse co-propagating with the proton bunch. In the first half of the plasma section proton beam will be self-modulated due to development of transverse two-stream instability. 10-20 MeV electrons should be side-injected into the developed plasma wave in the middle of this plasma section. Electron injection scheme assumes co-propagation of electron beam at a distance of ~1 cm from proton and laser pulse in the neutral Rb gas. In the middle of plasma section a superimposed magnetic field directs electrons towards the plasma wave. In this study we present the details of electron beam transport through the neutral gas as well as side-injection simulation. Some fraction of electron beam which is not captured by the plasma wave could be observed in the downstream low-energy electron spectrometer.

Speaker: Alexey Petrenko (CERN, Budker INP)

Slides petrenko.ppt

19:15 Proton bunch compression studies for the AWAKE experiment in the CERN SPS

The proposed proton-beam driven, plasma wake-field acceleration experiment AWAKE at CERN requires proton bunches with a high peak current and small transverse emittances extracted from the SPS at (300--400)~GeV. We present measurement results of bunch compression on the SPS flat top achieved by bunch rotation in longitudinal phase space for two optics available in the SPS. With the lower transition-energy optics, bunches with the same longitudinal emittance are more stable, but to obtain a similar bunch length, more RF voltage is required. Peak currents of up to 67~A at intensities above $3 \times 10^{11}$~p have been achieved. Longitudinal beam instabilities and the maximum available RF voltage limit to what degree the bunches can be shortened. Furthermore, due to potential-well distortion, the bunch length is increasing with intensity. First simulations give an estimate on how much could be gained from the planned upgrades of the RF systems and alternative bunch compression methods.

Speaker: Dr Helga Timko (CERN)

Slides Timko_2013-06.pdf Timko_2013-06.pptx

18:00 → 19:30 WG3 - Electron beams from electromagnetic structures, including dielectric and laser-driven

Convener: Prof. James Rosenzweig (UCLA)

18:00 High Gradient Wakefield Generation at the Upgraded Argonne Wakefield Accelerator Facility

The recently upgraded AWA facility is being commissioned. Operation of the new L-Band RF gun with a Cesium Telluride photocathode will generate long electron bunch trains, with high charge per bunch (up to 100 nC). The six new linac tanks will boost the beam energy to 75 MeV, making it an extremely well suited drive beam to excite wakefields in structures. One of the main goals of the facility is to generate RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage. Initial plans for the demonstration of two stages of acceleration will also be presented.

Speaker: Dr Manoel Conde (Argonne National Laboratory)

Slides conde_wg3.PDF

18:25 Recent Dielectric Wakefield Acceleration Results at FACET

Speaker: Prof. James Rosenzweig (UCLA)

Slides ROSENZWEIG.pptx

18:50 Analytical and Numerical Studies of Underdense and Overdense Regimes in Plasma-Dielectric Wakefield Accelerators

One of the advanced accelerator concepts is acceleration of particles by wakefields excited by relativistic electron bunches in dielectric structures. One problem of this method is the emittance growth of the accelerated beam due to its angular divergence. To focus the accelerated bunches, we suggest using a plasma that fills the vacuum channel of the dielectric unit. The plasma-dielectric structure under investigation is a dielectric-lined circular waveguide that has a transport channel filled with isotropic plasma. In the linear theory approximation (overdense plasma) the total field is represented as a sum of the plasma wave, the eigen waves of the dielectric waveguide, and the quasistatic field of the bunch. It is shown that at a certain plasma density the superposition of the plasma wave and the dielectric waves allows the acceleration of the witness bunch by the field of the dielectric wave together with simultaneous focusing by the plasma wave. For the overdense plasma regime the results of analytical investigations coincide well with results of particle-in-cell simulations (PIC). Also, we carried out a PIC simulation of the underdense (“blowout”) regime of wakefield excitation in the unit.

Speaker: Dr Gennadiy Sotnikov (NSC Kharkov Institute of Physics and Technology)

0 Sotnikov_summary.pdf

Slides Sotnikov.pdf

19:10 Subpicosecond Bunch Train Production and Tunable Energy Chirp Correction Using the Dielectric Wakefield Accelerator

Speaker: Dr Alexei Kanareykin (Euclid Techlabs LLC/ANL)

Slides Kanareykin_Dielectric_Acceleration_Elba_FINAL.pdf

18:00 → 19:30 WG4 - Future accelerator concepts incl. gg, beam transport (applications)

Convener: Prof. Andrei Seryi (John Adams Institute for Accelerator Science)

18:00 Traveling-Wave Thomson-Scattering and optical FELs

We show that optical free electron lasers in the X-ray range can be realized using Traveling-Wave Thomson-scattering (TWTS). TWTS provides long interaction lengths in the centimeter to meter range with undulator periods in the micron range. These can be accomplished with existing petawatt class lasers as optical wigglers in a side scattering geometry by tilting the laser pulse front. TWTS circumvents both the nonlinear Thomson intensity threshold and the Rayleigh-length limit which in head-on Thomson-scattering prevents the SASE process to occur. Furthermore TWTS offers tuneability in the scattered wavelength via the incidence angle and flexibility in the optical undulator length. In this talk we discuss the FEL dynamics of relativistic electrons in TWTS and quantify the influence of dispersion effects on the laser pulse properties and showing that they can be suppressed effectively. We present a self-consistent 1.5D FEL-theory which accounts for the oblique incident laser pulse and give scaling laws on the interaction geometry and FEL-amplification with respect to incidence angle and electron beam parameters. We finally present numbers on expected experimental performance for laser and electron beam parameters that will be available at HZDR.

Speaker: Mr Klaus Steiniger (Helmholtz-Zentrum Dresden-Rossendorf)

Slides steiniger-klaus_TWTS.pptx

18:30 IRIDE: An Interdisciplinary Research Infrastructure based on Dual Electron linac&laser

We describe in this talk a preliminary proposal of a new large infrastructure for fundamental and applied physics research. Conceived as an innovative and evolutionary tool also for multi-disciplinary investigations in a wide field of scientific, technological and industrial applications, it will be a high intensity “particle beams factory”, based on a combination of a high duty cycle radio-frequency superconducting electron linac and of a high energy laser. It will be able to produce a high flux of electrons, photons (from infrared to γ-rays), neutrons, protons and eventually positrons and muons, that will be available for a wide national and international scientific community interested to take profit of the most worldwide advanced particle and radiation sources.

Speaker: Massimo Ferrario (LNF)

Slides IRIDE_EAAC_Ferrario.pdf

19:00 IRIDE Round Table discussion (tentative)

19:30 → 20:30 Wine and Poster Session

19:30 a novel plasma source for beam driven wakefield acceleration

A proton driven plasma wakefield accelerator (pdpwa) experiment using CERN proton bunches is proposed by the Advanced Wake Field Accelerator (AWAKE) collaboration. 12 cm, 400 GeV CERN proton beam enters a 10 meter long plasma and the transverse selfmodulationinstability causes the proton beam to self modulate. The modulated beam behaves as a sequence of microbunches and starts resonantly driving a large wake (~GV/m). In this wake a ~20 MeV copropagating electron bunch will be injected. The plasma source is a 10 meter long Rubidium vapor which is fully tunnelionized by a laser. There is a strict requirement on the plasma uniformity. For the injected electron bunch to stay in the accelerating and focusing phase of the plasma wake the relative nonuniformity anywhere along the Rb vapor is not to exceed 0.2%. The plasma source developed at the Max Planck Institute for Physics is presented. Rb is confined in a long, 2 cm diameter heated pipe. The required uniformity is satisfied for a range of densities around optimum density of (7x10^15 cm-3). Fast valves provide beam access to the source. The source design, the effect of the valves, the expected neutral and plasma densities will be presented.

Speaker: Dr Erdem Oz (Max Planck for Physics)

19:30 Amplification of a Surface Electromagnetic Wave by a Running Over Plasma Surface Ultrarelativistic Electron Bunch as a New Scheme for Generation of Terahertz Radiation

The surface electromagnetic waves (SEW) on plasma-like media attract special attention of researchers due to their unique properties. The SEW are widely applied in physical electronics due to its high close to light phase and group velocity leading to its uncomplicated generation by relativistic electron bunches and output from plasma. We discuss the theoretical problem of SEW amplification with the help of ultrarelativistic monoenergetic electron bunch running over flat plasma surface. Such a problem of generation of three-dimensional electromagnetic wave (wakefields) in plasma with the help of ultrarelativistic electron and ion bunches through Cherenkov resonance radiation was solved in our earlier work. In the present work we apply this method. It is shown that when the ratio of electron bunch number density to plasma electron number density multiplied by a powered to 5 relativity factor is much higher than 1, the SEW saturation electric field induced by trapping of bunch electrons gains the magnitude ~ 10^11 V/m, the energy density flux (Poyinting vector) ~ 10^15 W /cm2 and does not approach the surface electromagnetic wave front breakdown threshold in plasma. Here, we discuss the possibility of generation of superpower Teraherz radiation on a basis of such scheme.

Speakers: Dr Konstantin V. Khishchenko (Joint Institute for High Temperatures RAS), Dr Saltanat Polatovna Sadykova (DESY, Hamburg)

19:30 An injector for multi-stage Laser Plasma Accelerators

Laser-plasma acceleration (LPA) is extensively studied since many years. The compactness of these systems as well as the unique properties of the electron source make them a promising alternative to conventional accelerators. Among the different research axis, the scientific community has started to work on multiple acceleration schemes with an aim to reach higher energy, preparing for experiments that will be possible to realize on future PW and multi PW laser facilities. In the context of the new up coming APPOLLON laser facility (10PW -15fs) on the Plateau de Saclay (France), CEA Saclay, LPGP-Université Orsay and LULI-Ecole Polytechnique collaborate to build and optimize an injector for a future 2-stage accelerator. We will present the technical choices that have been made to build the injector, and specially, the gas medium (mixtures with impurities) for ionization injection and control of the trapping processes. The experiments will be performed on UHI100 laser (100TW-25fs - CEA-Saclay). Related to the ionization injection issue, we will present encouraging results that have recently been obtained at the Lund Laser Centre, Sweden, in a collaboration between LLC, LPGP and CEA using gas mixtures with impurities, comparing LPA in capillaries and in gas jets.

Speaker: Dr sandrine dobosz dufrénoy (CEA-Saclay - DSM/IRAMIS/SPAM)

19:30 Concepts of Short Period RF Undulators

Several concepts for room-temperature RF undulators, fed by cm- or mm- wavelength radiation and aimed to produce ~1 nm wavelength radiation using relatively low energy electron beams, are considered. The preliminary analysis shows that requirements to electron beam quality and to RF power become more severe with wavelength reduction (the undulator parameter and the acceptable energy spread in electron beam are to be scaled almost linearly). In order to satisfy these requirements, we suggest to build an undulator of several separate segments, each segment introduces a high-Q cavity fed by its own multi-megawatt RF source. The 30 GHz pulsed gyroklystron or possibly gyrotrons at 30 - 300 GHz, already elaborated and tested in IAP RAS, are appealing candidates. These sources can provide the effective undulator period of 0.5 - 0.05 cm, the undulator parameter of the level from 0.01 to 1, and the effective field length of 50 cm for each segment. The design of undulator cavity at centimeter waves is based on waveguide technique, but at millimeter waves the three-mirror cavity design is proposed. All designs avoid problems with a co-propagating wave destroying beam optics and spectra of the scattered optical radiation.

Speaker: Dr Sergey Kuzikov (Institute of Applied Physics, Russian Academy of Sciences)

19:30 Design of a Plasma Discharge Circuit for Particle Wakefield Acceleration

Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10–100 GVm−1), enabling acceleration of electrons to GeV energy in few centimetre. However, the quality of the electron bunches accelerated with this technique is still not comparable with that of conventional accelerators; Radiofrequency-based accelerators, in fact, are limited in accelerating field (10 − 100 MVm−1) requiring therefore kilometric distances to reach the GeV energies, but can provide very bright electron bunches. To combine high brightness electron bunches from conventional accelerators and high accelerating fields reachable with plasmas could be a good compromise allowing to further accelerate high brightness electron bunches coming from LINAC while preserving electron beam quality. Following the idea of plasma wave resonant excitation driven by a train of short bunches, we have started to study the requirements in terms of plasma for SPARC_LAB. In particular, here we focus on the ionization process; we show a simplified model to study the evolution of plasma induced by discharge, very useful to design the discharge circuit able to fully ionize the gas and bring the plasma at the needed temperature and density.

Speaker: Maria Pia Anania (LNF)

19:30 Diagnostic considerations for the Plasma Wakefield Acceleration experiment proposed at PITZ

The proposed experiment is to set up a plasma oven in the Photo Injector Test Facility at DESY, Zeuthen Site (PITZ), beam line to study the self-modulation of electron beams when they passes through a laser generated Lithium (Li) plasma. In the experiment an oven will vaporize Li which will be ionized with a laser pulse, creating plasma with density of 〖10〗^15 〖cm〗^(-3). To gain insight into the experimental conditions it is necessary to measure the plasma density. Several methods of absorption spectroscopy and laser interferometry have been proposed in the literature for neutral and plasma density measurements of Li in a plasma oven [1]. Here we are presenting a comparison of plasma density measurement methods which are candidates to be realized in the PITZ PWA experiment. [1] “Photo-ionized lithium source for plasma accelerator applications”, P.Muggli et. al. IEEE Transactions on Plasma Science, Vol. 27, No. 3, June 1999.

Speaker: Mr Gaurav Pathak (University of Hamburg)

19:30 Diagnostics of laser wakefield electron accelertion inside capillary tubes

Intense ultrashort laser pulse interacting with plasma expels electrons from the regions of high intensity and leaves in its wake a plasma wave. The ultrahigh longitudinal electric field associated to this plasma wave, of the order of 100 GV/m, is capable of accelerating electrons to GeV-class over only a centimeter-scale distance. Meanwhile, the accelerated electrons are transversely wiggled by the radial electric field of the plasma wave during the process of acceleration, generating a synchrotron-like X-ray radiation. The measured X-ray beams are therfore can be used to diagnose the process of electron accelration in the plasma. An experiment was recently conducted at the Lund Laser Centre (LLC) in Sweden in order to characterize capillary-guided laser wakefield accelerators. We will present the results of diagnostics about electron trajectory, the number of electron oscillation, and the accleration extension in the plasma using the observed X-ray beams.

Speaker: Mr Jinchuan JU (Universite Paris-Sud 11)

19:30 Extending the Acceleration Length in Laser-Plasma Techniques

Laser-plasma accelerator techniques exploit longitudinal electric fields related to plasma waves which are excited by the laser ponderomotive force. Laser-driven plasma wave electric fields can overcome up to 5 orders of magnitude those produced by conventional RF accelerators. For an electron injected in a plasma wave to obtain high energy gain, not only intense electric fields but also wide acceleration lengths along the plasma wave are required. The ponderomotive force, which supports the plasma wave, decreases because of both energy-depletion and diffraction (Rayleigh length). To extend the Rayleigh length, several techniques exist, based on the plasma refraction index modulation. The most common is the laser beam optical guide in preformed plasma channels, obtained by focusing a laser pulse on a gas jet or by producing a plasma in a capillary filled with gas and ionized by an electric discharge. Secondly, self-focusing can be used, in which laser radiation induces a local variation of plasma refraction index. The aim of these studies is to overcome the main drawbacks related to the present limitations on the acceleration lengths, to realise compact accelerating systems capable of reaching GeV energies interesting for High Energy Physics and further applications.

Speakers: Danilo Giulietti (PI;LNF), Ms Giada Cantono (Università di Pisa)

19:30 High energy electrons from interaction with a structured gas-jet at FLAME

In this poster we discuss the spectra of the electrons produced in the laser-plasma acceleration experiment at FLAME. In the experiment the laser is set to propagate along the longitudinal axis of a 10mm gasjet to study the role of density gradients. Thomson scattering optical imaging shows that a significant laser depletion takes place typically in the first 4mm. Angular and spectral properties of accelerated electrons are then studied to infer the regime of acceleration occurring in the plasma. Our LANEX data show highly collimated bunches (<1mrad) with a relatively stable pointing direction (<10mrad). Typical bunch electron energy ranges between 50MeV and 200MeV with occasional events of higher energy up to 1GeV. Spectra are characterized by large energy spread with evidence of spectral modulations. Fully 3DPIC numerical simulations confirm that laser intensity and plasma density are in the range where electron acceleration takes place by self-injection in the bubble-like structure. This phase characterizes the first few mm of the laser propagation. In the second phase a new regime comes in, where the propagation of the relativistic electron bunch in the undisturbed gas jet possibly drives a new wakefield acting to remodulate the spectral shape of accelerated electrons.

Speaker: Mr Gabriele Maria Grittani (Università di Pisa)

19:30 High-Quality Multi-GeV Electron Beams from Auto-Resonance Laser-Acceleration

Results from many-particle simulations will be presented that demonstrate feasibility of generating an electron bunch of over 10-GeV energy and ultra-high quality (relative energy spread of order 10−4) by cyclotron auto-resonance. The scheme employs a static magnetic field oriented along the direction of propagation of a laser beam. Tremendous energy gain by the electron from the laser field occurs if the electron injection conditions (initial position and velocity) and the laser and magnetic field parameters conspire to achieve auto-resonance: when the cyclotron frequency of the electron around the lines of the magnetic field match the Doppler-shifted frequency of the laser as seen by the electron. Accelerated electron bunches of the above-mentioned characteristics are suitable for fundamental high-energy particle physics research. In our calculations, the laser peak intensities and axial magnetic field strengths required are up to about 1018 W/cm2 and 60 T, respectively. Gains exceeding 100 GeV are shown to be possible when weakly focused pulses from a 200-PW future laser facility are used.

Speaker: Prof. Yousef Salamin (American University of Sharjah)

19:30 Laser Pulse Shaping for Multi-Bunches Photoinjectors

Plasma Wake Field Accelerators need electrons in a train of ps or sub-ps spaced multi-bunches (Muggli). THz sources (Shen) and pump-probe experiments (Zewail) are also interested in ps-spaced electron bunches. Main schemes used for laser multi-bunch generation involve birefringent crystals, interference of two delayed and stretched pulses or the use of a Dazzler and a 4f system with an amplitude mask in the Fourier plane (Boscolo). We are testing two schemes in Sparc_lab facility: one based on birefringent crystals (Petrillo) and the other is a new idea based on retardation of different spectral components of the laser pulse using quartz plates in the Fourier plane of a 4f system. P. Muggli, M.J. Hogan, C. R. Physique, v. 10, p. 116, 2009 A. H. Zewail, J. Phys. Chem. A, v. 104, p. 5660, 2000 Y. Shen et al., Phys. Rev. Lett., v. 107, p. 204801, 2011 M. Boscolo et al., Nucl. Instr. Meth. Phys. Res. section A, .v 577, p. 409, 2007 V. Petrillo et al., Observation of time-domain modulation of FEL pulses by multi-peaked electron energy spectrum, submitted to Phys. Rev. Lett.

Speaker: Fabio Villa (INFN - LNF)

19:30 Laser-driven Radiation Sources for Applications

High power laser technology is now leading to the realization of new large laser infrastructures aimed at the exploration of new physical domains. Meanwhile, all-optical radiation sources based on acceleration with self-injection are also being considered as Thomson/Compton sources. At the same time, the practical use of laser-driven sources will require the development of high-efficiency and high-repetition rate laser systems to achieve source performances with the required high average power needed for most applications. In this paper we show the results of a recent development in all-optical laser-plasma acceleration for electron and secondary radiation sources carried out at ILIL and FLAME laser installations. We will show results of electron microradiography and comparative dosimeter with standard electron sources with sub 10 MeV electrons. Also we will present the status of an all-optical Compton γ-ray source driven by self-injection at electron energy range up to 1 GeV, including experimental data on self-injection and numerical simulations using advanced 3D GPU particle in cell code. Finally, an overview will be given of the development of a laser scheme based on Yb for a high energy amplifier for future high-rep rate laser systems.

Speaker: Dr Leonida Antonio Gizzi (CNR and INFN)

19:30 Nanofabrication at the LZH

Miniaturization is a hot topic for the future of accelerator science. Reducing the size of accelerator devices, undulators and beam transport units could provide compact brilliant light sources. We present how micro- and nanostructuring techniques can be combined to manufacture these components. Nanolithography enables us to fabricate planar strutures with feature sizes of about 250 nm. Two-Photon-Polymerization allows the structuring of three-dimensional scaffolds with the same resolution. The combination of lithographic routines and post-laser-processes deliver arrays of homogenous-sized nanoparticles in a very precise order.

Speaker: Mr Kristian Boroz (Laser Zentrum Hannover)

19:30 Pre-Excitation Studies for Rubidium-Plasma Generation

The key element in the Proton-Driven-Plasma-Wake-Field-Accelerator (AWAKE) project is the generation of highly uniform plasma from Rubidium vapor. The standard way to achieve this aim is to use large power laser which can assure the over-barrier-ionization (OBI) along the 10 meters long active region. The Wigner-team in Budapest is investigating an alternative way of uniform plasma generation. The proposed Resonance Enhanced Multi Photon Ionization (RETMI) scheme probably can be realized by much less laser power. Theoretical considerations and status report about the preparatory work on the experiment are presented.

Speaker: Vesztergombi Gyorgy (Wigner RCP)

19:30 Preliminary studies and design for laser-driven electron and x-ray sources at the Salamanca High-Power Laser Facility (CLPU)

We present the current state of the high power laser facilities in Salamanca, Spain, and introduce a roadmap for first experiments on laser-driven electron acceleration and related femtosecond x-ray sources (Betatron radiation, Thomson/Compton Scattering). Prospective beam energies are estimated using the particle-in-cell code CALDER-CIRC. As a supplementary experimental tool, a laboratory for target characterization and tests on X-ray diagnostics, using a high repetition rate femtosecond laser (1 kHz, 7 mJ, 120 fs), has been set up.

Speaker: Mr Andreas Döpp (Centro de Laseres Pulsados)

19:30 Relativistic charged-particle beam dynamics via the generation of wake field

A new theoretical approach to describe the dynamics of the relativistic charged-particle beam propagation via the generation of wake field is provided. The wake field is derived starting from the Lagrangian of a relativistic test charged particle. The beam dynamics is described using the appropriate Hamiltonian for the beam particle and a quantum description is provided using a recently developed theory. The eective Hamiltonian shows a new additional slow response eect to the longitudinal dynamics due to the relativistic propagation of the beam in a longer time scale. Using such approach, further study of the eects of both the transverse (focusing/defocusing) and the longitudinal (acceleration/deceleration) components of the wake field in the self-consistent PWF excitation is proposed.

Speaker: Fatema Tanjia (NA)

19:30 Reproducibility of Electron Beams from Laser Wakefield Acceleration in Capillary Tubes

Laser wakefield acceleration of electrons is a promising scheme for future high energy particle accelerators, able to provide accelerating gradients up to 100 GeV/m. One of the key issues for the use of laser plasma accelerators is the control of the parameters of the accelerated electron beam. Relativistic electron beams are commonly generated by the complex process of self-injection in the non-linear regime of laser wakefield. To evaluate the feasibility of using such a mechanism as injector for an accelerator, the reproducibility of electron beam properties as a function of the laser parameters was studied. In the frame of a Franco-Swedish collaboration, a study of the stability of electron beams produced by laser wakefield self-injection was performed at the laser facility of the Lund Laser Center. A multi-TW stabilized Ti:sapphire laser beam was sent into capillary tubes containing hydrogen gas in order to self-inject and accelerate electrons. The influence of laser and capillary parameters on electron beam properties was analyzed. We will discuss conditions required for the production of reproducible electron beams generated from stabilized laser wakefield.

Speaker: Mr Frédéric Guillaume Desforges (Laboratoire de Physique des Gaz et des Plasmas, CNRS-Université Paris-Sud XI)

19:30 Resonantly-enhanced multiple-pulse laser plasma wakefield acceleration

We present progress on experiments being conducted at Oxford University on resonantly-enhanced multiple-pulse laser plasma wakefield acceleration (MP-LWFA). Our initial experiments concentrate on the use of frequency domain holography to visualise wakefields driven in helium by a single high energy pulse and then short trains of pulses generated by either appropriately chirping the single pulse and passing it through a birefringent crystal, or by using stacked Michelson interferometers. The use of trains of low energy laser pulses may enable the application of efficient, high repetition rate (> 1kHz) fibre laser systems to drive MP-LWFA in the future. We present numerical simulations of the electron density oscillations and accelerating gradients that we expect to produce with these pulse trains and first results from our experiment.

Speaker: Mr J. Cowley (Atomic & Laser Physics, Clarendon Laboratory, University of Oxford, UK)

19:30 Transformer Ratio Studies for Single Bunch Plasma Wakefield Acceleration

In the Plasma Wakefield Acceleration (PWFA) plasma oscillations are driven by ultra relativistic electron beams. The ratio of the maximum accelerating field behind the driving beam (bunch) and the maximum decelerating field inside the driving beam (bunch) is defined as Transformer Ratio, a key parameter that determines the energy gain in particle acceleration. We investigate the transformer ratio for different shapes of a single driving bunch: one dimensional simplified, fluid, relativistic, cold plasma equations have been numerically solved. A complete map of the transformer ratio is obtained varying: bunch shape, bunch length and density ratio. The systematic scan highlights that the transformer ratio critically depends on the bunch shape and on the density ratio. Moreover the same systematic scan both in the linear as well as in the non-linear regime clearly verifies how the theoretical limit of 2 for the transformer ratio can be easily exceeded in the non-linear regimes for specific shapes. The simplified model easily permits to find an optimal working point and can be straightforwardly extended to optimize the resonant multi-bunch wakefield excitation.

Speaker: Mr Francesco Massimo (Department SBAI, Sapienza Università di Roma)

Tuesday, 4 June

08:30 → 10:30 Plenary 3

Convener: Dr Jens Osterhoff (Deutsches Elektronen-Synchrotron DESY)

08:30 Review on Plasma Accelerators Driven by Laser Beams

Speaker: Prof. Zulfikar Najmudin (Imperial College London)

Slides Najmudin_EAAC_2013.pdf

09:10 Review on Plasma Electron Driven by Electron Beams and First FACET Results

Speaker: Dr Vitaly Yakimenko (SLAC)

Slides EAAC13_Beam_Driven_PWFA_-_Hogan.pdf

09:50 Review on Advanced Diagnostics for Laser-Driven Plasma Accelerators - New Insights Into the Acceleration Process

When generating relativistic plasmas with high-power laser systems, small-scale particle accelerators can be realized producing particle pulses exhibiting parameters complementary to conventional accelerators. To further improve the stability of these particle pulses and ultimately to be able to tailor the energy spectrum towards their sutability for various applications, the physics underlying the different acceleration scenarios need to be understood as well as possible. To be able to resolve these acceleration processes diagnostics well-suited for this plasma environment need to be designed and realized. In this presentation, several techniques will be introduced and recent results will be discussed. They have lead to the first time-resolved visualization of the plasma wave necessary for laser-driven electron acceleration with unprecedented temporal and spatial detail. We could observe for the first time the formation, its non-linear evolution, the actual breaking of the plasma wave and ultimately its transformation into one single remaining plasma wave oscillation, also referred to as the plasma bubble. These results weill be discussed in detail and compared to the results from multi-dimensional numerical simulations. Furthermore, diagnostic techniques relevant for laser-driven ion acceleration based on optical and particle probing will be presented.

Speaker: Prof. Malte Kaluza (University of Jena, Helmholtz-Institute Jena)

Slides Kaluza.pptx

10:30 → 11:00 coffee break

11:00 → 12:40 Plenary 4

Convener: Dr Arnd Specka (LLR - Ecole Polytechnique - CNRS/IN2P3)

11:00 Simulations of Plasma Based Accelerators

Plasma based accelerator technology, supported by the extreme accelerating fields driven by the interaction of high-intensity laser and particle beams with plasmas, has matured significantly, promising the development of a new generation of plasma based accelerators, capable of delivering high quality electron/ion beams for multiple applications. These developments have relied heavily on numerical modeling for the understanding of the underlying physics and identification of optimal regimes. Given the highly-nonlinear processes occurring in these scenarios, the tool of choice for numerical modeling has been fully relativistic particle-in-cell codes. However, the computational requirements of these algorithms for detailed full scale 3D modeling of these scenarios require efficient use of state-of-the-art Petascale supercomputing systems throughout the full simulation. This requires not only efficient, multi-scale, simulation algorithms, but also matching these algorithms to the computing hardware, ensuring both good parallel scalability to hundreds of thousands of computing cores, and high floating point efficiency at the single core level. We discuss the new developments that address these issues, focusing on different algorithms that allow for separating the laser / target spatial and temporal scales, allowing for longer interaction lengths, for electron wakefield acceleration, and for overcritical laser interaction scenarios, for ion acceleration, and also on numerical developments that range from multi-dimensional dynamic load balancing and hybrid distributed / shared memory parallelism to the vectorization of the PIC algorithm. Illustrations of these developments will be given for electron and ion plasma based accelerators.

Speaker: Prof. Ricardo Fonseca (ISCTE - IUL)

Slides fonseca_eaac_2013.pdf

11:40 AWAKE: A Proton-Driven Plasma Wakefield Experiment at CERN

Short, high-energy proton (p+) bunches can drive GV/m accelerating fields over long distances (>>10m) in low-density plasmas (1e15-1e15/cc) . Long p+ bunches subject to the self-modulation instability (SMI) form a train of micro-bunches that can resonantly drive accelerating fields of comparable amplitude over similar distances. The AWAKE experiment proposed at CERN aims to study the development of the SMI of p+ bunches in plasmas and to test the acceleration of externally injected electrons. AWAKE will use the ~12cm-long bunches of the SPS in the CERN CNGS facility. The SMI will be seeded using a laser pulse ionization front co-propagating within the p+ bunch. Numerical simulations show that seeding drives the SMI to saturation in ~4m of plasma and determine the final phase of the wakefields. Low energy electrons can either be injected from the side in a long, continuous plasma source, or on axis with two plasma sources. They are accelerated to a few GeVs in the remaining ~6m of plasma. The AWAKE current experimental plan and goals will be presented. Other SMI experiments at Brookhaven and SLAC relevant to AWAKE will also be briefly mentioned.

Speaker: Prof. Patric Muggli (Max-Planck-Institut für Physik)

Slides EAAC2103InvitedMuggli.pdf

12:10 Advanced Positron Sources

Positrons sources are a critical system for the future lepton colliders projects. Due to the large beam production emittance and the limitation given by the target mechanical stress and heating, the main collider parameters fixing the luminosity are constrained by the e+ sources. In this context also the damping ring performances boundary conditions are given by the positron beam injected. Different schemes are at present taken into account to increase the production and capture efficiency, to reduce the impact of the deposed energy in the production target and to increase the injection efficiency in the damping ring. The main schemes and new development for the next colliders will be reviewed and the different developed technologies illustrated.

Speaker: Dr alessandro variola (LAL IN2P3 CNRS)

Slides elba4.pptx

12:40 → 16:00 lunch

16:00 → 17:30 WG1+4

16:00 Prospects for High-Repetition-Rate Multi-Pulse Laser Wakefield Accelerators

In recent years laser wakefield accelerators – in which the plasma wave is driven by a single high-intensity laser pulse – have generated quasi-monoenergetic electron beams with energies up to the GeV range. However, the driving lasers used have low wall-plug efficiencies (<1%) and operate at pulse repetition rates of at most a few Hz. Scaling this approach to generate electron beams – or radiation sources driven by them – with high pulse repetition rates and high mean power would therefore be extremely challenging. An alternative approach would be to deploy a train of properly spaced low-energy laser pulses to excite the wakefield synchronously. This concept was first studied theoretically in the 1990s, but there has been relatively little subsequent work. In this talk we discuss the prospects for multi-pulse laser wakefield acceleration (MP-LWFA) driven by pulse trains generated by ultrafast fibre lasers. This approach offers the prospect of efficient, GeV-scale plasma accelerators operating at pulse repetition rates in the kHz range. MP-LWFAs of this type would be an ideal driver for ultrafast, high-mean-flux plasma wiggler and undulator radiation sources.

Speaker: Prof. Simon Hooker (University of Oxford)

16:18 High efficiency fiber laser systems for wake-field particle accelerators

An important driver of scientific progress has always been the envisioning of applications far beyond existing technological capabilities. In the case of laser physics, one of these applications is laser wake-field particle acceleration and possible future uses thereof, such as in collider experiments, or for medical applications such as cancer treatment. To accelerate electrons and positrons to multi-GeV energies, a laser architecture is required that allows for the combination of high efficiency, Petawatt peak powers, and Megawatt average powers. Developing such a laser system would be a challenging task that might take decades of aggressive research, development, and, most important, revolutionary approaches and innovative ideas. In the presentation we will present rare-earth-doped fiber laser based systems for a compact, efficient, scalable, and cost-effective high-average and high-peak power ultra-short pulse laser concept. The proposed approach relies on the spatially and temporally separated amplification of ultrashort laser pulses in waveguide structures, followed by coherent combination into a single train of pulses (or into a programmable multi-pulse structure) and into a single beam with increased average power and pulse energy.

Speaker: Prof. Jens Limpert Limpert (FSU Jena)

16:36 Non-laminar charged particle beams from quantum to thermal regime

The standard classical description of non-laminar charge particle beams in paraxial approximation is extended to the context of two wave theories. The first theory is the so-called Thermal Wave Model (TWM) that interprets the paraxial thermal spreading of the beam particles as the analog of the quantum diffraction. The other theory, hereafter called Quantum Wave Model (QWM), takes into account the individual quantum nature of the single beam particle (uncertainty principle and spin) and provides the collective description of the beam transport in the presence of the quantum paraxial diffraction. An envelope equation is derived for both TWM and QWM regimes. In TWM we recover the well known Sacherer equation whilst, in QWM we obtain the evolution equation of the single-particle spot size, i.e., single quantum ray spot in the transverse plane (Compton regime). We show that such a quantum evolution equation contains the same information carried out by an evolution equation for the beam spot size (description of the beam as a whole). This is done by defining the lowest QWM state reachable by a system of overlapping-less Fermions.

Speaker: Prof. Renato Fedele (NA)

Slides EAAC_2013_Fedele.pdf EAAC_2013_Fedele_WG1+4_summary.pdf

16:54 Study of LWFA as Injectors for Synchrotron Light Sources

In addition to their high beam energies and small facility footprint, the short bunch lengths customary for Laser Wakefield Accelerators make them very interesting as injectors for Synchrotron Light Sources. Exemplary investigations have been carried out using the ANKA storage ring. As the length of the electron bunch influences both the duration and the spectrum of the emitted Synchrotron radiation, particular emphasis has been put on the evolution of the longitudinal phase space. We show that it is possible to store a significant fraction of the injected electrons. However, the bunch length increases much faster than one might naively expect, reaching its equilibrium length within a few hundred turns.

Speaker: Mr Steffen Hillenbrand (CERN, KIT)

Slides 2013.06_eaac_hillenbrand.pdf

17:12 Primary Beam Lines for the AWAKE project at CERN

The construction of the first proof of principle experiment which uses proton bunches to generate plasma wakefield acceleration (AWAKE) is proposed at CERN. The facility could be installed at the end of the existing CNGS proton beam tunnel as the neutron physics program terminated in 2012. Minor modifications of the existing proton line have to be applied to fit the experiment, adapt the optics to fulfill the AWAKE requirements and integrate the laser for gas ionisation and self modulation seeding. Studies on the electron beam line design and evaluation of space charge effects on the optics are presented.

Speaker: Dr Chiara Bracco (CERN)

Slides AWAKE_ELBA-Chiara.pptx

16:00 → 17:40 WG2 - Ion beams from plasmas

Convener: Prof. julien fuchs (luli-cnrs)

16:00 Radiation pressure assisted acceleration of ions using multi-component foils in high-intensity laser-matter interactions

We report on the observation of mono-energetic features for different charge states of carbon and modulations in the proton spectra by accelerating ions out of an ultra-thin 15 nm polymer foil. For a rather low intensity of 6x10^19 W/cm2, and a very high contrast, detailed studies based on high statistics were done. Careful comparison with numerical results indicates a two-step acceleration model based on radiation-pressure acceleration (RPA) as long as the laser is interacting with the foil and a target-normal-sheath like acceleration (TNSA) of the system afterwards. Scans on the dependence of the incident laser polarisation, the pre-plasma conditions and the target thickness were done. By varying the polarization we were able to tune the energy of the modulation. Inducing a pre-plasma by a second, counter-propagating pulse, made it feasible to decrease the thermal background spectrum and to trigger the mono-energetic features at the same time. This experiment, at the origin of the intensity range for which RPA is predicted, gives evidence for scheduled experiments of our collaboration at other laser-systems, enabling intensities in the range of 10^21..22 W/cm2.

Speaker: Dr Bastian Aurand (Department of physics; Lund University)

Slides EAAC13_WG2_Aurand.pptx

16:25 Ion acceleration beyond 100MeV/amu in relativistic transparent laser-matter interactions

The ultra-high contrast and relativistic intensities (>10^20 W/cm2) available at the LANL Trident laser for the first time allowed sub-micron solid matter laser interaction dominated by relativistic transparency of the target. This interaction efficiently couples laser momentum into all target ion species, making it a promising and competitive alternative to conventional accelerators on a much wider basis. However, little experimental research or simulations have up to now studied conversion efficiency or beam distributions, which is essential for advanced application, such as ion based fast ignition (IFI) or hadron cancer therapy. We here present experimental data addressing these aspects for both carbon C6+ ions and protons in comparison with the TNSA regime. Unique high resolution measurements of angularly resolved carbon C6+ and proton energy spectra for targets ranging from 30 nm to 25 micron - recorded with an ion wide angle spectrometer - are presented and used to derive thickness scaling estimates. While the measured conversion efficiency for C6+ reaches up to ~7%, peak energies of 1 GeV and 120 MeV have been measured for C6+ and protons, respectively.

Speaker: Dr Daniel Jung (Quee's University Belfast)

Slides EAAC_D_Jung.pptx

16:50 Ion Acceleration and Neutron Production Based on Relativistic Transparency of Solids

We present experimental results on the first short pulse laser driven neutron source powerful enough for applications. For the first time an acceleration mechanism based on the concept of relativistic transparency has been used to generate neutrons. This mechanism not only provides much higher particle energies, but also accelerated the entire target volume, thereby circumventing the need for complicated target treatment and no longer limited to protons as an intense ion source. We demonstrated proton beams of up to 150 MeV and deuteron beams up to 180 MeV driven by the 80 J, 200 TW TRIDENT laser at Los Alamos National Laboratory. As a consequence we have demonstrated a new record in laser-neutron production, not only in numbers, but also in energy and directionality based on an intense deuteron beam. This enabled the use in imaging applications with high temporal resolution. The beam contained, for the first time, neutrons with energies in excess of 200 MeV and showed pronounced directionality, which makes them extremely useful for a variety of applications. The results also address a larger community as it paves the way for short pulse lasers as a neutron source and open up research to a broad academic community.

Speaker: Prof. Markus Roth (Technische Universität Darmstadt)

Slides TALK_EAAC13_Roth_.pdf

16:00 → 17:30 WG5 - instrum - Plasma sources and instrumentation

Conveners: Alessandro Cianchi (ROMA2;LNF), Dr Jens Osterhoff (Deutsches Elektronen-Synchrotron DESY)

16:00 TADPOLE for longitudinal electron-bunch diagnostics based on electro-optic upconversion

Electron-bunch diagnostics are desired to utilize unambiguous, non-destructive, single-shot techniques. Various methods fulfill the latter two demands, but feature significant ambiguities and constraints in the reconstruction of time-domain electron-bunch profiles, as for example uncertainties due to the phase retrieval of coherent radiation using the Kramers-Kronig relation. We present a novel method of upconverting the THz-field spectrum of fs electron bunches at the free-electron laser FLASH into the near-infrared in an electro-optic crystal. This technique allows the single-shot detection of its longitudinal form factor in both, amplitude and phase. The spectral phase and amplitude information is measured and thus the temporal profile reconstructed using temporal analysis by dispersing a pair of light E-fields, also known as TADPOLE. This is a combination of frequency resolved optical gating (FROG) and spectral interferometry, enabling the temporal measurement of low-power laser pulses. In this experiment, a narrow-bandwidth laser pulse detecting the longitudinal electric field of an electron bunch is interfered with a broadband and FROG-characterized reference pulse. The longitudinal beam profile may therefore be unambiguously inferred from the generated interferogram and the detected spectral-phase-information of the reference pulse.

Speaker: Mr Jan-Patrick Schwinkendorf (Deutsches Elektronen-Synchrotron)

Slides 16_00_Schwinkendorf.pdf

16:20 First single-shot and non-intercepting longitudinal bunch diagnostics for comb-like beam by means of Electro-Optic Sampling

Precise measurements of the temporal profile of ultrashort electron bunches are of great interest for the optimization and operation of plasma wakefield accelerators (PWFAs). Electro Optical Sampling (EOS) based technique have been already demonstrated the possibility to successfully measure the longitudinal properties of electron beams. The electric field of a travelling electron bunch induces birefringence in an electro-optic crystal placed at few millimeters with respect to the beam trajectory. The amount of birefringence depends on the electric field and it is probed by monitoring the change of polarization of a laser pulse, a 800 nm wavelength directly derived from the Ti:sapphire photocathode laser of SPARC_LAB. Such a scheme does not require a dedicated laser oscillator neither a fast gated camera, resulting in a really affordable diagnostic. In our experiment the Spatial Decoding of EOS has been applied for a single-shot direct visualization of the time profile of a comb-like electron beam, consisting of two bunches, about 100 fs long, sub-picosecond spaced with 160 pC total charge. A cross-checking of the absolute time calibration has been performed with both a Transverse-Deflecting RF Structure (TDS) and a Michelson Interferometer, resulting in an excellent agreement.

Speaker: Riccardo Pompili (LNF)

Slides EOS_pompili_talk.pdf

16:40 Single shot longitudinal profile monitors using Smith-Purcell radiation

Smith-Purcell radiation has the potential of providing information on the longitudinal profile of an electron bunch. Research is ongoing both at FACET and at SOLEIL to study how this radiation could be used to build a single shot longitudinal profile monitor. A brief status of these two experiments will be presented, including recent experimental results showing how a change in bunch length modifies the Smith-Purcell radiation signal.

Speaker: Mr Nicolas Delerue (LAL, CNRS and Université Paris-Sud 11)

Slides 16_40_delerue.pdf

17:00 Experimental Measurements of Electron-Bunch Trains in a Laser-Plasma Accelerator

Spectral measurements of visible coherent transition radiation produced by a laser-plasma-accelerated electron beam are reported. The significant periodic modulations that are observed in the spectrum result from the interference of transition radiation produced by multiple bunches of electrons. A Fourier analysis of the spectral interference fringes reveals that electrons are injected and accelerated in multiple plasma wave periods, up to at least 10 periods behind the laser pulse. The bunch separation scales with the plasma wavelength when the plasma density is changed over a wide range. An analysis of the spectral fringe visibility indicates that the first bunch contains most of the charge.

Speaker: Dr Olle Lundh (Lund University)

Slides lundh-eaac-2013.pdf

16:00 → 17:30 WG6 - Theory and simulations

Convener: Luis O. Silva (Istituto Superior Técnico)

16:00 Challenges in Modeling Beam Driven Plasma Accelerators

Particle-in-cell simulations play an important role in advancing the knowledge of laser (LWFA) and plasma (PWFA) wakefield accelerators. However, full-scale simulations in the conditions of near future experiments are very computationally intensive. Accurately modeling these scenarios therefore requires state-of-the-art numerical codes combined with novel algorithms capable to capture key physics while minimizing computational requirements. This talk will show simulation results of next generation LWFA's and PWFA's describing challenges associated with full-scale modeling of these scenarios. A key challenge for LWFAs is performing three-dimensional simulations of electron acceleration meter-long plasmas in self-injection regimes. As a first step towards this goal we present LWFA simulations of externally injected electrons in boosted frames, and describe a new ponderomotive guiding center algorithm that could be used to explore self-injection in meter-long LWFAs. In connection with future experiments at CERN and SLAC, one of the critical challenges for future generations of PWFAs is three-dimensional modeling of self-modulated plasma wakefield accelerators. We present simulation results of self-modulated PWFAs driven by electrons, positrons and protons emphasizing the importance of 3D modeling to include all key physics expected in experiments.

Speaker: Dr Jorge Vieira (Instituto Superior Tecnico)

Slides E-AAC-JVieira.pdf

16:25 New Algorithms for Cylindrical PIC Code - Application to Wakefield Accelerators

Cylindrical coordinates are often used to simulate PWFA or LWFA with PIC codes, as it is much faster than using a 3D cartesian mesh while it gives similar results, thanks to the axial symmetry of the wakefield. We describe here recent advances in numerical algorithms for such PIC codes using cylindrical coordinates. First, we define new splines for macro-particles interpolation on the mesh. These splines should be specific to the cylindrical case and thus different from the standard splines used for cartesian mesh. Then, we present an adapted version to cylindrical geometry of the exact charge conservation scheme proposed by Esirkepov [1]. Finally, based on a new solver for Maxwell equations [2], we show that the numerical Cherenkov radiation can be removed, which greatly improves the accuracy of the electron beam parameters prediction. Simulations with the code CALDER-CIRC [3] are at last presented to show the effects and advantages of these new schemes. [1] T. Zh. Esikkepov, Comp. Phys. Comm. 135, 144-153 (2001) [2] R. Lehe et al., Phys. Rev. STAB 16, 021301 (2013) [3] A. Lifschitz et al., J. Comp. Phys. 228, 1803-1814 (2009)

Speaker: Dr Xavier Davoine (CEA DAM DIF)

Slides EAAC2013_XDavoine.ppt

16:40 Fast and accurate simulations of 10 GeV-scale laser plasma accelerators

Because of their ultra-high accelerating gradient, laser plasma based accelerators are contemplated for the next generation of high energy colliders and light sources. The upcoming BELLA project will explore acceleration of electron bunches to 10 GeV in a meter long plasma, with a PW-class laser driven wakefield. Simulations of such stages are challenging because of the disparity of length scale between the laser wavelength that needs to be resolved and the simulation length. We report on recent developments of the Laser Envelope Model, a reduced model for laser-plasma interactions that has previously demonstrated orders of magnitude speedup. We present the implementation of the model in cylindrical coordinates, allowing rapid prototyping of laser acceleration stages. We discuss the performance benefits as well as limitations and trade-offs of this model.In parallel, high frequency noise in PIC simulations makes it difficult to accurately represent beam energy spread and emittance. We show that calculating the beam self-fields using a static Poisson solve in the beam frame dramatically reduces particle noise, allowing for more accurate simulation of the beam evolution. Work supported by DOE/HEP under grants DESC0004441, DE-FC02-07ER41499 and DE-AC02-05CH11231 (including use of NERSC).

Speaker: Dr Jonathan SMITH (Tech-X UK Ltd)

Slides Tech-X-LPA.pptx.pdf

16:55 Numerical Investigation of Bunch-Driven PWFA in Quasi-Nolinear Regime

In the framework of Plasma Based Wakefield Acceleration (PBFA), a new acceleration scheme has been proposed to combine high efficient blow-out regimes, where the driving electron bunch forms a totally rarefied plasma channel, with the conditions assuring resonant excitation of a plasma waves at the linear frequency. This optimal configuration can be achieved by using a train of properly interlaced electron bunches carrying small charges but still having high number density and hence pulse strength nb/n0 > 1, as necessary to form a ”bubble” structure. Here we present a numerical investigation of this quasi-nonlinear configuration using the fully 3D ALaDyn PIC code, as a preparatory work to design optimal conditions for the COMB experimental set-up at the SPARC-LAB laboratories. In particular we consider a bunch train containing three driving bunches with charges Qb=[10−50]pC and energy Eb=50−100MeV, followed by a smaller charge witness bunch. For plasma density n0=10^16cm−3, numerical accuracy is usually assured by a proper resolution of the relevant skin depth d_e≃47μm scale. Here the computation is more demanding, since quasi-nonlinear regimes require a bunch transverse size and beam channel radius rb << d_e

Speaker: Dr Pasquale Londrillo (INFN-Bologna (Italy))

17:10 Kick off for Discussion on the Future Directions for Theory and Modeling of Plasma Based Accelerators

17:30 → 18:00 coffee break

18:00 → 19:30 WG1+4

18:00 Radiative losses in plasma-based electron accelerators in ultrahigh energy limit

The electrons accelerated in plasma-based accelerator undergo betatron oscillations and emit synchrotron radiation. The energy loss to synchrotron radiation may seriously affect electron acceleration. The electron dynamics under combined influence of the constant accelerating force and the classical radiation reaction force is studied. It is shown that electron acceleration cannot be limited by radiation reaction. If initially the accelerating force was stronger than the radiation reaction force then the electron acceleration is unlimited. Otherwise the electron is decelerated by radiative damping up to a certain instant of time and then accelerated without limits. It is shown that regardless of the initial conditions the infinite-time asymptotic behaviour of an electron is governed by self-similar solution providing that the radiative damping becomes exactly equal to 2/3 of the accelerating force. The relative energy spread induced by the radiative damping decreases with time in the infinite-time limit. The multistage schemes operating in asymptotic acceleration regime when electron dynamics is determined by radiation reaction are discussed.

Speaker: Dr Kostyukov Igor (Institute of Applied Physics RAS, Nizhny Novgorod State University)

Slides Kostyukov-radiative_losses.pdf

18:18 Merging Conventional and Laser Wakefield Accelerators

Laser wakefield accelerators deliver high quality electron beams in terms of emittance and bunch length. However there are also parameters which cannot compete with conventional machines, namely the spectral width as well as the shot to shot stability. One reason for that is that there is no direct access to the injection mechanism of electrons into the plasma wakefield. Injecting a well-characterized electron beam produced by a conventional accelerator into a plasma wakefield could help to solve that problem: Measuring the difference in the electron spectrum in such a pump-probe type experiment should yield the possibility to directly reconstruct the field distribution. From that point comparison with theoretical approaches as well as results from particle-in-cell codes could lead to a better understanding of the injection process. At DESY in Hamburg there is a suited conventional accelerator for such a type of experiment, the Relativistic Electron Gun for Atomic Exploration (REGAE). We report on the status of the beamline extension at REGAE and the plans towards the external injection project with the goal to deduce the wakefield and further improve the stability of laser wakefield

Speaker: Mr Benno Zeitler (CFEL &amp; UHH)

Slides 20130604_EAAC_Zeitler.pdf

18:36 Development of a kHz laser plasma accelerator for ultrafast electron diffraction

We will present the status of the FEMTOELEC project (ERC starting grant) whose goal is to develop a kHz, laser-plasma accelerator generating femtosecond electron bunches for applications to ultrafast electron diffraction. Simulations of the interaction of few millijoule, few cycle laser pulses with an underdense plasma have been performed and show that high-quality sub-fs electron bunches at the MeV level can be generated from this interaction [1]. Such ultrashort bunches are suitable for probing ultrafast structural changes in condensed matter via ultrafast electron diffraction. We will then show the results of first proof of principle experiments performed using a 8 mJ, kHz laser interacting with a 100 micron underdense plasma. Electron beams at 100 keV and with kHz repetition rates have been obtained [2]. High quality diffraction patterns on single crystal Gold samples have been measured, showing the potential of laser-plasma accelerators for electron diffraction applications [3]. References: [1] A. Lifschitz et al., New J. Phys. 14 053045 (2012). [2] Z.-He et al., New J. Phys. accepted for publication [3] Z.-H. He et al., Appl. Phys. Lett. 102, 064104 (2013).

Speaker: Dr Jerome Faure (LOA)

Slides Elbe_2013_FAURE.pdf

18:54 Collider design issues based on proton-driven plasma wakefield acceleration

Simulation shows that the plasma wakefield driven by a high energy proton bunch can accelerate a bunch of electrons to the energy frontier (TeV) in a single stage of acceleration. It therefore offers us a novel solution to design a collider (either an electron-position collider or an electron-proton collider) using the existing high-energy proton machines, e.g. SPS or the LHC at CERN. This talk will discuss some key issues, e.g. the luminosity, COM energy, phase slippage, positron acceleration in designing the future colliders based at the CERN accelerator infrastructure.

Speaker: Dr Guoxing Xia (Cockcroft Institute and the University of Manchester)

Slides collider_design_based_on_PDPWA.pdf

19:12 Transport line for a multi-staged laser-plasma acceleration: DACTOMUS

The laser-plasma acceleration is one of the most promising techniques to reach very high acceleration gradients of about 100 GeV/m. In order to push this acceleration scheme in the domain of the very high energies, the Equipex project CILEX was launched with the laser APOLLON. One of the main topics of this project is to study the multi-staged acceleration. It consists in generating and pre-accelerating the electrons in a first laser-plasma stage to transport them up to a second stage where the electrons are accelerated again thanks to another laser pulse. The project DACTOMUS relies on a collaboration CEA-IRFU, LAL and LLR, and tends to the study and realization of such a transport line between these two stages. Firstly, a prototype will be developed and tested by the groups of CEA-IRAMIS-SPAM / LPGP and LULI on the installation UHI100 (CEA-SPAM). This collaboration must enable to realize the first acceleration stage. For the transport line prototype, the main difficulties are to realize a very compact and a very energy accepting line with diagnostics to characterize the electron beam. We will present here the optics of this line, its performances and the inserted diagnostics.

Speaker: Dr Antoine Chance (CEA IRFU)

Transparents 2013_06_04_EAAC.pdf

18:00 → 19:40 WG2 - Ion beams from plasmas

Convener: Prof. julien fuchs (luli-cnrs)

18:00 Laser ion acceleration with low density targets: a new path towards high intensity, high energy and high current ion beams

Intense research is being conducted on sources of laser-accelerated ions and their applications, motivated by the exceptional properties of these beams: high brightness, high spectral cut-off, high directionality, laminarity, and short duration (~ps at the source). It was recently experimentally shown that a promising way to accelerate ions to higher energies and in a collimated beam is to use under-dense or near-critical density targets instead of solid ones. In this case, volume effects dominate, enhancing the laser-to-proton energy conversion, and allowing reaching high ion energies with a high number of accelerated ions. The transition between various laser ion acceleration regimes depending on the density gradient length (controlled by the delay between the lasers) was studied at LULI 200 TW and LLNL Titan Facilities using a two-laser setup. A first ns pulse was focused on a thin target to explode it and a second laser was focused on the exploded foil. Protons with energies significantly higher than the ones reached for solid targets were obtained while keeping a good beam quality. These results demonstrate that low-density targets are a promising candidate for an efficient compact proton source.

Speaker: Patrizio Antici (LNF)

Slides ANTICI.pdf

18:25 Mapping of intense magnetic fields in relativistic laser plasma interaction

The propagation of ultrashort laser pulse at relativistic intensity in micrometric scale underdense Helium plasma is studied in detail, exploring densities in the range of 1% to 10% n_c. The plasma is probed to simultaneously reconstruct the evolution in time of electron density and polar magnetic field. Magnetic fields that are produced in plasma result from the propagation of hot electrons currents, therefore magnetic fields analysis appears to be a powerful tool for inferring the properties of the currents in plasmas, revealing the richness of processes invoked and giving crucial physical insights of the interaction. Experimental data supported by 3D PIC simulations enable us to observe more in detail the evolution of electron currents during and after the laser propagation and to explore the mechanisms of formation of the intense magnetic fields, in the order of ~MGauss. Experiments are carried out in a range of densities where no experiments have been performed before. Theoretical works have shown that copious phenomena resulting from non linearity of physical processes and related instabilities are expected to be produced. Deeper exploration of the studied interaction goes in the direction of building gas-based laser ion sources.

Speaker: Dr Alessandro Flacco (LOA)

Slides Flacco-EAAC13.pdf

18:50 Tunable Achromatic Focusing Optics for High-Current Laser-Accelerated Proton Beams

This presentation will focus on demonstrating the possibility to highly focus high energy proton beams by self-generated magnetic field produced during the interaction of a high contrast, high intensity laser beam with thin solids targets of various materials. We will show, using experiments and simulations, that knowing the dynamics of such self-generated magnetic field allow us to control the collimation of high energy proton beam.

Speaker: Prof. julien fuchs (luli-cnrs)

Slides Presentation_Fuchs_EAAC.pdf

19:15 Dose enhancement and localisation by combining reduced mass targets and a pulsed solenoid for radiobiological effectiveness studies of laser accelerated protons

Compact laser-driven proton therapy accelerators are a potential alternative to complex and expensive conventional accelerators, but still require substantial development in reliable beam generation, transport and dosimetric monitoring as well as validation in radiobiological studies. We report on systematic investigations of ultrashort pulse laser-driven acceleration of protons from thin targets of narrow lateral dimension, so-called reduced mass targets (RMTs). A robust maximum energy enhancement (almost doubled) was found when compared to reference irradiations of plain foils of same thickness and material. Combining RMTs with a pulsed high-field solenoid for particle capturing, as developed at Helmholtz-Zentrum Dresden-Rossendorf, gives the potential to enhance the dose per pulse and localise it within a small irradiated volume. This might enable radiobiological effectiveness studies on volumetric tumours with laser-accelerated proton beams via in vivo animal irradiations – a nescessary step in the translational research chain towards laser-driven proton therapy of cancer.

Speaker: Mr Florian Kroll (Helmholtz-Zentrum Dresden-Rossendorf)

Slides #2013-EAAC-Kroll.pptx

18:00 → 19:00 WG5 - instrum - Plasma sources and instrumentation

Conveners: Alessandro Cianchi (ROMA2;LNF), Dr Jens Osterhoff (Deutsches Elektronen-Synchrotron DESY)

18:00 THz diagnostics for the plasma density and charged particle self-modulation measurement in AWAKE experiments

Plasma wakefield acceleration (PWFA) experiments using CERN SPS proton bunches are now under development within the AWAKE-collaboration. A density uniformity on the order of 0.2% is required to maintain the witness electrons on the accelerating and focusing phase of the wakefields. Fast and precise methods for single shot plasma density measurements with time windows of about 100ns are necessary. One method under study is the measurement of the cut-off at the electron plasma frequency. For the PWFA experiments the plasma electron density should be tunable between 10^14 and 10^15 cm-3, resulting in cut-off frequencies of 90GHz to 300GHz, respectively. To achieve a density sensitivity of 0.2% the cut-off frequency must be measured with a resolution better than 100MHz at 10^14 cm-3. Two schemes for broadband microwave generation and detection are proposed: chirped photo-mixing and THz-time domain spectroscopy. As an alternative method optical emission spectroscopy is also investigated. In addition, the dispersive Fourier Transformation and time stretching methods are studied for single shot measurements of proton bunch modulation in frequency domain. The conceptual ideas, initial simulations, the experimental setup and preliminary measurement results will be presented.

Speaker: Dr roxana tarkeshian (Postdoc)

Slides 18_00_Tarkesian.pdf

18:25 Pickup design for arrival-time measurements at REGAE

Laser wakefield accelerators are capable of accelerating electron bunches to energies on the GeV scale over acceleration distances of only a few cm. However, the beam quality still can be improved especially in terms of energy spread and emittance. In order to gain more insight into the acceleration process, the high-quality electron bunches produced by the conventional accelerator REGAE at DESY are planned to be injected into a laser driven wakefield. The timing between driving laser and probing bunch is of utmost importance since the wakefield structure is typically on the order of a few 100 fs. Several measurement techniques are available for measuring the arrival-time of the electron beam with fs resolution. Based on the detection scheme (resonant or broadband), different pickup structures can be used (cavities, striplines, buttons). As the bunch charge in this case is as low as 100 fC, the selection of the detection scheme and with that the selection of the pickups is extremely challenging. Namely, such a low charge of the beam induces a very low voltage levels in the pickups. The selected pickup structures need to be optimized in order to maximize the induced voltage levels in the pickups.

Speaker: Mr Aleksandar Angelovski (TU Darmstadt)

Slides 18_25_Angeloski.pdf

18:00 → 18:30 WG6 - Theory and simulations

Convener: Luis O. Silva (Istituto Superior Técnico)

18:00 Discussion on the Future Directions for Theory and Modeling of Plasma Based Accelerators

18:20 Conclusion of Discussion

21:30 → 22:30 Jazz Concert

Wednesday, 5 June

08:30 → 10:30 Plenary 5

Convener: Andrea Ghigo (LNF)

08:30 Laser-Driven Ion Acceleration: Review of Mechanisms, State of the Art and Applications

Ion acceleration driven by high intensity laser pulses is attracting an impressive and steadily increasing research effort. Experiments over the past 10-15 years have demonstrated, over a wide range of laser and target parameters, the generation of multi-MeV proton and ion beams with unique properties such as burst emission, high brilliance, and low emittance. The talk will provide an overview of the state of the art of ion acceleration by discussing both the established sheath acceleration mechanism (or TNSA), and emerging mechanisms (Radiation Pressure Acceleration, Break Out Afterburner), which hold the promise for acceleration to GeV/nucleon energies with next generation laser facilities. Proposed, and already implemented, applications of these beams will also be discussed.

Speaker: Prof. Marco Borghesi (Queen's University Belfast)

Slides Borghesi.pdf

09:10 The European Light Infrastructure

Speaker: Wolfgang Sandner (Max Born Institute Berlin)

09:50 Shortest Possible Beams from Conventional Accelerators

Speaker: Dr Klaus Floettmann (DESY)

Slides EAAC_2013_Short_Beams_Floettmann.pptx

10:30 → 11:00 coffee break

11:00 → 12:40 Plenary 6

Convener: Dr Marie-Emmanuelle Couprie (Synchrotron SOLEIL)

11:00 Experimental and Theoretical Progress LC Final Focus Design and ATF2 Facility

Speaker: Prof. Andrei Seryi (John Adams Institute for Accelerator Science)

Slides A-Seryi-EAAC-5-June-2013-final.pdf

11:40 C-Band LINAC Module Developments

The SwissFEL C-band main linac consists of 26 modules and accelerates, at a repetition rate of 100 Hz, two electron bunches, spaced by 28 ns, from 350 MeV up to 5.8 GeV. Each module is composed of four 2-meter long constant gradient accelerating structures each with 113 cells, one 50 MW klystron and one Barrel Open Cavity (BOC) pulse compressor. The choice to operate at the American C-band frequency of 5712 MHz was dictated by the large availability in the market of the klystrons and RF components at this frequency. While klystrons and waveguides are procured from commercial companies, the accelerating structures and pulse compressor are developed in house for future industrialization. A strong R&D program was launched, from the RF design, manufacturing to the high power tests, exploiting ultra-precise turning and outstanding high gradient and breakdown rate (BDR) results, proving the reliability of the C-band technology at 100 Hz repetition rate. Four short (13 cells) constant impedance structures were successfully produced without implementing dimple tuning features. Gradients as high as 35 MV/m (large iris design) and 57 MV/m (small iris design) were achieved at 1 µs pulse length, about three times the nominal value, limited only by the available 50 MW klystron power. The very first 2-meter long accelerating structure also confirms the high-precision machining and the choice to avoid dimple tuning. The BOC prototype represents a further impressive C-band technology result: for 50 MW klystron power and 3 µs pulse length, at 100 Hz repetition rate, a compressed pulse up to 300 MW peak was measured in phase jump mode. For the same pulse length and 40 MW klystron power, an encouraging BDR of 5·10-7 was obtained.

Speaker: Dr Alessandro Citterio (PSI - Villigen)

Slides EAAC2013_Citterio.ppt

12:10 Inverse-Free-Electron Laser Accelerators for Advanced Light Sources

In this talk I will discuss the Inverse Free Electron Laser scheme as a compact high gradient accelerator solution for driving advanced light sources such as soft x-ray free-electron laser amplifiers. We will present recent results from two different IFEL acceleration experiments, one carried out at BNL using a CO2 driver laser and a helical geometry and the other one at LLNL using a high power short pulse Ti:Sa laser system. These experiments demonstrate the feasibility of achieving GV/m gradients and GeV beam energies with the IFEL scheme. The optically microbunched output of the IFEL accelerator well matches the requirement for a modelocked FEL capable of generating attosecond pulse trains.

Speaker: Prof. Pietro Musumeci (UCLA)

Slides Musumeci.pptx

12:40 → 16:00 lunch

16:00 → 17:30 WG1+6

Convener: Luis O. Silva (Istituto Superior Técnico)

16:00 Wakefield dynamics and electron acceleration in guiding structures

The compression and acceleration of an external electron bunch into the laser wakefield is studied and compared to analytical predictions. It is shown, for a laser propagating in a plasma channel, that the nonlinear laser pulse dynamics together with the finite laser spot size influence the electron bunch compression and acceleration due to the reduction of the laser pulse group velocity. The transverse bunch dynamics and loading effect determine the final bunch charge and density and restrict the compressed sizes of the trapped and accelerated electron bunch. A comparison of different codes for modelling of multi-GeV accelerator stages are presented and discussed. The problem of precise focusing and pointing stability of the laser pulse, necessary for the regular structure of the wakefield generated in a capillary is analyzed. The three-dimensional theoretical model is elaborated and used to describe the propagation of laser pulses in dielectric capillary waveguides under imperfect coupling and focusing conditions with broken cylindrical symmetry. It is demonstrated that matching cones can considerably increase the transmission of laser pulses through the capillary, but cannot mitigate the requirements on the precision of the laser pulse focusing into a capillary.

Speaker: Prof. Nikolay Andreev (Joint Institute for High Temperatures of RAS)

Slides Andreev.pdf

16:15 All-optical control of electron injection for GeV-scale acceleration in mm-scale, tapered plasmas.

The accelerating bucket of a laser-plasma accelerator (a cavity of electron density maintained by the pulse radiation pressure) evolves slowly, in lock-step with the optical driver, and readily traps background electrons. The trapping process can thus be controlled by purely optical means. Sharp gradients in the nonlinear refractive index produce a large frequency red-shift, localized at the leading edge of the pulse. Negative group velocity dispersion associated with the plasma response compresses the pulse into a relativistic optical shock (ROS), slowing the pulse (and the bucket), reducing the electron dephasing length, and limiting energy gain. Even more importantly, the ponderomotive force of the ROS causes the bucket to constantly expand, trapping copious unwanted electrons, polluting the electron spectrum with a high-charge, low-energy tail. We show that a negatively chirped drive pulse with an ultra-high (~400 nm) bandwidth: extends the dephasing length; prevents ROS formation through dephasing; and almost completely suppresses continuous injection. High quality, GeV-scale electron beams can be thus produced with 10-TW-class lasers (rather than PW-class) in mm-scale (rather than cm-scale), high-density plasmas. Plasma density tapering further delays dephasing, providing additional boost in beam energy.

Speaker: Dr Serguei Kalmykov (University of Nebraska - Lincoln)

16:30 Electron laser wakefield acceleration with the CILEX facility, a PIC simulation based investigation

CILEX (Centre Interdisciplinaire Lumiere Extreme) is the Interdisciplinary Center on EXtreme Light. This facility located in the Paris area will host the APOLLON-10P laser, which will deliver short pulses, down to possibly 15 fs, at a still unreached instantaneous power of 10PW, and the associated infrastructures and experimental setup which will offer the possibility to perform scientific breakthroughs in various domains. We have used the particle-in-cell (PIC) code Calder-Circ, to determine the typical characteristics of the electron beams that could be generated with this laser in its very first phase when only 1 PW will be available in the case of self-injection in the blow out regime. We compare initially matched pulses against initially over-focused pulses in terms of injection capabilities and dark current suppression. In the first case, self-guiding sets in very quickly whereas in the second, the laser diffracts, forcing the bubble to expand before reaching a self guided stage. We also try to evaluate the importance of having a 15 fs pulse versus a more standard 25 fs pulse.

Speaker: Dr Arnaud Beck (LAboratoire Leprince Ringuet)

Slides beck_eaac2013.pdf Summary slides

16:45 Optical Transverse Injection: A New Mechanism of Injection in Laser-Wakefield Acceleration

Although laser-wakefield accelerators have demonstrated accelerating gradient on the order of 1 TeV/m, they currently still lack the stability and bunch quality that is needed for many applications. Nevertheless, these properties strongly depend on the electron injection into the accelerating cavity, and improved bunch quality can in principle be obtained by choosing a proper method of injection. After reviewing the main existing mechanisms of injection, a mechanism recently identified through PIC simulations – optical transverse injection – will be described. This mechanism occurs in the colliding-pulse configuration, in which a counter-propagating pulse collides with the driving laser and triggers injection. While in the previously explored regimes of parameters, the mechanism was essentially longitudinal (i.e. effectively 1D), in a well-define range of yet unexplored parameters a transverse mechanism (i.e. fully 3D) appears. Importantly, this mechanism generates high-quality electron bunches having simultaneously high charge (50-100 pC), low energy spread (2%) and low emittance (0.15 mm.mrad). In addition, the required laser and plasma parameters are available at a number of existing laser facilities, making it an interesting scheme for future applications.

Speaker: Mr Remi Lehe (Laboratoire d'Optique Appliquee (LOA))

17:00 Radiation Reaction in Laser Wakefield Accelerators

Recent results showed that laser wakefield accelerators can provide all-optical configurations to study classical radiation reaction with present-day laser technology. In this all optical configuration self-injected electron bunches with energies on the order of 1 GeV, which have been reported by several laboratories, leave the plasma and collide head-on with an intense laser (for example I~10^21 W/cm2, tfwhm~30fs), therefore maximizing the radiation reaction impact on the electron bunch. While interacting with the laser in this configuration, 1 GeV electrons can lose up to 40% of their initial energy. This is a strong and easily measurable signature. We present a numerical and analytical study covering parameters that can be achieved with current and near-future laser systems in this configuration, employing full-scale ab-initio 3-dimensional particle-in-cell simulations. Higher laser intensities soon to come online (> 10^22 W/cm2) will provide even stronger radiation reaction on LWFA produced electron bunches, and also the possibility to enter the QED regime. The impact of radiation reaction on bunch parameters such as emittance and divergence is also addressed.

Speaker: Ms Marija Vranic (GoLP/IPFN - Instituto Superior Tecnico)

17:15 External-Injection experiment at the SPARC_LAB facility

At the SPARC_LAB facility of INFN-LNF we are installing two transport lines for ultra-short electron bunches and an ultra-intense laser pulse, generated by the SPARC photo-injector and by the FLAME laser in a synchronized fashion at the tens of fs level, to co-propagate inside many different gas filled devices. The main aim of this experiment is to demonstrate that a conventionally produced high brightness electron beam can be accelerated by a plasma wave without a significant degradation of its quality. We will show the status of the installations and overview the expected outcomes of plasma acceleration with respect to the different acceleration methodologies we foresee to implement.

Speaker: Dr Andrea Renato Rossi (INFN - Milan)

Slides ROSSI_Ext_inj_SPARC_LAB.pdf

16:00 → 17:40 WG2 - Ion beams from plasmas

Convener: Prof. julien fuchs (luli-cnrs)

16:00 Experimental Studies of Ion Charge Equilibrium in the Warm Dense Matter Regime Using Laser-Based Plasma

In the WDM regime, the charge equilibrium and stopping power of particles differs significantly from that of both cold matter and ideal plasma due to free electron contributions, plasma correlation effects and electron degeneracy. The creation a WDM state with a temporal duration consistent with the particles used to probe it has been extremely difficult to achieve experimentally. Advantageously, the short-pulse laser platform allows the potential to produce WDM[5,6] along with relatively short bunches of protons compatible of such measurements. Using ion carbon beams generated by high intensity short pulse lasers we perform measurements of single shot mean charge equilibration in cold or isochorically heated solid density aluminum matter. We demonstrated that plasma effects in such matter heated up to 1 eV do not significantly impact the equilibration of carbon ions with energies 0.045–0.5 MeV/nucleon. Furthermore, these measurements allow for a first evaluation of semiempirical formulas or ab initio models that are being used to predict the mean of the equilibrium charge state distribution for light ions passing through warm dense matter. Also, we made measurements of the proton energy loss within the material compared to the measured medium density profile allows the stopping power to be determined quantitatively. The results from heated matter show that the stopping power of 450 keV protons is dramatically reduced within heated hydrogen plasma.

Speaker: Dr Sophia Chen (CNRS/LULI)

16:25 Laser Induced Light Ion Acceleration at LNF

Laser-matter interaction at relativistic intensities open up new research fields in the particle acceleration and related secondary sources, with immediate applications in medical diagnostics, biophysics, material science, inertial confinement fusion, up to laboratory astrophysics. In particular laser-driven ion acceleration is very promising for hadron therapy once the ion energy will attain a few hundred MeV. The results of a “Start to End” simulation for a hybrid scheme are presented in another contribution in this conference. As a matter of fact the limited value of the energy up to now obtained for the accelerated ions is the drawback of such innovative technique to the real applications. For this reason at LNF experiments are in progress, in the frame of the INFN-LILIA project, aimed to increase the energy of the ions in ultrahigh intensity regime (I>1019W/cm2) and at the same time to develop a post-acceleration of the ions suitably injected into a high field LINAC. The status of the experimental activity and first results will be presented.

Speaker: Prof. Danilo Giulietti (Physics Department of University and INFN, Pisa-I)

Slides EAAC2013_Giulietti.ppt

16:50 LIGHT – from laser ion acceleration to future applications

Creation of high intensity multi-MeV ion bunches by high power lasers became a reliable tool during the last 15 years. To face their main problems (large divergence and exponential energy spectrum), the LIGHT collaboration was founded (Laser Ion Generation, Handling and Transport). The collaboration consists of several university groups and research centers, namely TU Darmstadt, JWGU Frankfurt, HI Jena, HZDR Dresden and GSI Darmstadt. The central goal is building a test beamline for merging laser ion acceleration with conventional accelerator infrastructure at the GSI facility and provide highest intensity beams for applications. In the latest experiments, low divergent proton bunches with a central energy of up to 10 MeV and containing >10^9 particles could be provided at up to 2.2 m behind the plasma source, using a pulsed solenoid. In a next step, a radiofrequency cavity will be added to the beamline for phase rotation of these bunches, giving access to sub-ns bunch lengths and reaching highest intensities. The author will speak for the LIGHT collaboration and give a view on the collaboration's activities and acomplishments so far.

Speaker: Mr Simon Busold (Technische Universität Darmstadt)

Slides EAAC2013June05_SBusold.pdf

17:15 ELIMED: a Future Hadrontherapy Concept Based on the Laser-Driven Beams

Laser accelerated proton beams have been proposed to be used in different fields of research. In particular, a great interest has been focused in the possibility of replacing conventional accelerating machines with laser-based accelerators in order to develop a new concept of hadrontherapy centers which could result more compact and cheaper. In this context a research project has been launched by INFN-LNS researchers from Catania (IT) and FZU researchers from Prague (Cz) aiming to demonstrate the clinical applicability of optically accelerated protons. Surely, several tasks, going from the laser-target interaction to the dosimetry, need to be fulfilled in order to reach this goal. Great importance has the design and realization of a transport beam-line able to give to the beam the right characteristic in terms of energy spectrum and angle distribution in order to perform dosimetric tests both on detectors and on cells. A group from LNS is in charge for the realization of an energy selector system (ESS) that will be the main component of the transport beam-line. This work will report the studies carried out on the ESS using GEANT4 Monte Carlo code which gives important information on the design optimization and also comparisons with some experimental results.

Speaker: Dr Valentina Scuderi (INFN - LNS)

Slides elba2013_scuderi_summary.pdf

16:00 → 17:30 WG4 future - Future accelerator concepts incl. gg, beam transport (applications)

16:00 Follow-up on Overview of Advanced Compton Sources (tentative)

Speaker: Luca Serafini (MI)

16:30 Follow-up on Advanced positron Sources )tentative)

Speaker: Dr alessandro variola (LAL IN2P3 CNRS)

17:00 Follow-up on Shortest Possible Beams from Conventional Accelerators (tentative)

Speaker: Dr Klaus Floettmann (DESY)

16:00 → 17:30 WG5 - instrum - Plasma sources and instrumentation

Conveners: Alessandro Cianchi (ROMA2;LNF), Dr Jens Osterhoff (Deutsches Elektronen-Synchrotron DESY)

16:00 Issues with phase space characterization of laser-plasma generated electron beams

Plasma acceleration is the new frontier in particle beam accelerators. Using the strong electric fields inside a plasma it is possible to achieve accelerating gradients orders of magnitude larger with respect to the actual technologies. Different schemes, using completely different approaches, have been proposed and several already tested, producing beams of energy up to several GeV. Independently by the technique a precise determination of the emerging beam parameters is mandatory for the fine tuning of the process. The measurement of these parameters, in particular the phase space, is not trivial, mainly due to the large energy spread and to the tight focusing of these beams or to the background noise produced in the plasma channel. We illustrate the principal problems related to the diagnostic of this kind of beams and some of the proposed or already realized solutions.

Speaker: Alessandro Cianchi (ROMA2;LNF)

Slides 16_00_cianchi.pdf

16:25 High resolution laserwire electron beam size measurements and fibre laser development for high repetition rate laserwire applications

A laserwire is a non-invasive, high resolution particle beam size monitor based on Compton scattering that is required for future planned colliders and can also be used to estimate the size of the source in wakefield acceleration experiments. We present recent results from the high resolution laserwire transverse electron beam diagnostic installed at the Accelerator Test Facility 2 (ATF2) electron accelerator at KEK in Japan. Full characterisation of the propagation of the 150mJ, 167ps laser beam is used to deconvolve the transverse laserwire profile demonstrating the successful measurement of 1um scale vertical electron beam sizes, even with extreme aspect ratios. We also present progress in the development of high energy photonic crystal fibre based laser systems for laserwire measurements at MHz repetition rates, suitable for intra-bunch train scanning for planned accelerators such as the International Linear Collider, or beam size measurement in laser or particle driven plasma accelerators.

Speaker: Dr L. Corner (John Adams Institute, University of Oxford, UK)

Slides EAAC_June_2013.pptx

17:30 → 18:00 coffee break

18:00 → 19:30 WG1+6

Convener: Luis O. Silva (Istituto Superior Técnico)

18:00 Beam-Driven Plasma Acceleration with Density Downramp Injection at FLASH

Plasma acceleration exploits extreme electric fields (>10 GV/m) created in a plasma by high-current beams or high-intensity laser pulses, to accelerate charged particles. One of the most important aspects of making plasma acceleration a realistic technology for a wide range of applications is understanding and controlling the process of injecting particles into the plasma wake. Accurate adjustment of injection mechanism allows for high degree of control over phase-space and the overall quality of injected beam. In current studies we explore the possibility of injecting particles into a beam-driven wake by using transitions in plasma density. The parameters of the driver beam and the plasma correspond to the current design for plasma acceleration experiments planned at the FLASH facility at DESY. Studies were performed by means of 3D particle-in-cell simulations with the code OSIRIS. It was shown that the density downramp injection allows for trapping and acceleration of electron beams, with final low emittance and low slice energy spread. Various parameter scans were performed, investigating sensitivity of the injected beam qualities, such its as length, charge, energy spread, and correlations in phase-spaces, to initial parameters of the driver and the plasma ramp.

Speaker: Dr Julia Grebenyuk (DESY)

18:15 Numerical Modeling of Laser-Wakefield Electron Acceleration Inside a Dielectric Capillary Tube

Laser guiding inside a dielectric capillary tube offers a promising approach for building a multistage laser-wakefield accelerator. In this approach, a relativistic electron beam, produced externally, is injected into the wakefield, excited by the propagation of the laser pulse inside a gas filled dielectric capillary tube. In the quasi-linear regime of laser wakefield excitation, the typical capillary tube length, required to achieve multi-GeV (~ 5-10 GeV) energy gain, is expected to be in the range 1-2 m. Computationally efficient numerical simulations of laser-wakefield acceleration inside a long (~1-2 m) capillary tube are performed with the code WAKE-EP (Extended performances). This code is an upgrade of the quasi-static code WAKE [P. Mora and T.M.Antonsen, Jr., Phys. Plasmas 4, 217(1997)]. In WAKE-EP, the laser-wakefield excitation (in the quasi-linear regime) inside a dielectric capillary tube is simulated with the quasi-static approximation employed in WAKE and the acceleration of an externally injected electron bunch is described by conventional Particle-In-Cell (PIC) calculations. The capabilities of the code along with results of numerical simulations of electron acceleration to multi-GeV energies will be discussed.

Speaker: Dr Bhooshan Paradkar (LPGP, University of Paris Sud-11)

18:30 Lighting Up the Inner Workings of LWFA – How Radiative Particle-in-Cell Simulations can Shed New Light into the Dynamics of Laser-Accelerated Electrons

We present simulations of angularly resolved radiation spectra from laser-wakefield accelerated electrons (LWFA) based on classical Liénard-Wiechert potentials ranging from infrared to the X-ray wavelengths. These radiation spectra give insight into the momentum distribution with a spatial resolution small enough to study in detail the electron dynamics during the formation of the wakefield, the injection of electrons into the wakefield and in the coherent motion of electrons during acceleration. As spectral information is accessible in experiments, our results can serve as a valuable input to new diagnostics. A quantitative comparison of measured and simulated spectra poses a unique method to determine the phase space distribution of electrons in the LWFA process. Our code is capable of computing the spectra of all particles in the simulation and fully accounts for coherent effects. We thus can quantitatively predict the spectral intensities observed in experiment and are able to link them to specific phase space regions much smaller than the plasma wavelength. We show that radiation diagnostics can serve as a powerful tool to understand a large variety of plasma phenomena and how large-scale simulations of Petaflop performance can in the future help to optimize LWFA.

Speaker: Mr Richard Pausch (Helmholtz-Zentrum Dresden - Rossendorf)

Slides EAAC2013_rpausch_noAnimation.pdf

18:45 Two-Pulse Ionization Injection into Quasi-Linear Plasma Wakefields

To produce high quality electron beam from laser wakefield accelerators requires control of injection and trapping of electrons by the plasma wakefield. Several techniques for controlling injection have been proposed and demonstrated, but none has been shown to control injection into linear or quasi-linear wake-fields. We describe a scheme in which electrons ionized from a dopant by an “injection” laser pulse are trapped into the quasi-linear wakefield driven by a collinear “drive” pulse. The Rayleigh range of the injection pulse is chosen to be short, ensuring that the injection is localized; this can be achieved by using a small laser spot size or simultaneous space time focusing. This approach offers several advantages: electrons are injected close to the axis, with low transverse momentum and emittance; localized injection results in low relative energy spread; and the charge of the injected bunch may be controlled by varying the spot size of the injection pulse, or by adjusting the density of the dopant species. We analyze this scheme using 1D fluid, and 2D particle-in-cell simulations and use these to demonstrate controlled generation of electron beams with low transverse emittance and relative energy spreads of a few percent.

Speaker: Mr Nicolas Bourgeois (University of Oxford)

19:00 High-Quality Electron Beams from Ionization-Induced Self-Trapping in the Strong Blow-out Regime of Beam-Driven Plasma Wakes.

A new strategy for controlled ionization-induced trapping of electrons in beam-driven plasma wakes is proposed. The method exploits the strong wakefields excited by a longitudinally asymmetric ultra-relativistic electron-beam driver operating in a strong blow-out regime in order to selectively tunnel-ionize and trap electrons from a dopant species of high ionization potential. This work demonstrates the injection mechanism by means of 3D particle-in-cell simulations using the code OSIRIS. In these simulations an electron beam with a triangular current profile propagates through a precreated plasma of density 5x1017 cm-3 and excites strong wakefields. When these wakes cross a thin plasma column of 1000 μm doped with neutral helium, they trigger ionization and trapping of 3.8 pC of electrons in a 700 attoseconds long region of the wakefields phase-space. The trapped electron bunch is subsequently accelerated within a distance of 75.2 mm to energies of up to 4 GeV with a relative energy spread of 1%, normalized transverse emittances of 1 μm and a peak current of 3 kA.

Speaker: Dr Alberto Martinez de la Ossa (DESY)

19:15 New Exact Solutions of the Dirac Equation of a Charged Particle Propagating in a Strong Laser Field in an Underdense Plasma

In the present contibution we show that there are closed–form exact solutions of the Dirac equation of a charged particle moving in a strong classical laser field in a medium (which may be an underdense plasma of index of permittivity em (w) = 1 – wp2/w2 ). These solutions form a doubly infinite discrete set, labeled by two integer quantum numbers, representing a quantized spectrum of momentum components along the propagation direction and along the polarization of the laser field. Various properties of these new states will be discussed, and numerical illustrations of their wave functions will bw presented. Their relevance concerning possible quantum features of mechanisms of laser acceleration of electrons by high-intensity fields in an underdense plasma will also be discussed.

Speaker: Prof. Sandor Varro (Wigner Research Centre of Physics, Budapest, Hungary)

Slides Varro.pdf

18:00 → 19:30 WG4 future - Future accelerator concepts incl. gg, beam transport (applications)

Convener: Prof. Andrei Seryi (John Adams Institute for Accelerator Science)

18:00 Summary Preparation (tentative)

18:00 → 19:30 WG5 - instrum - Plasma sources and instrumentation

Conveners: Alessandro Cianchi (ROMA2;LNF), Dr Jens Osterhoff (Deutsches Elektronen-Synchrotron DESY)

18:00 Optical probing of laser-driven electron acceleration with synchronized few cycle pulses

Experiments on laser wake field acceleration rely heavily on numerical simulations to explain observed phenomena. This is mainly attributed to the unique properties of the acceleration structure, the plasma wave: The spatial extension in the order of a few micrometers and its propagation with nearly the speed of light have so far defied a direct observation. Even pulses with durations as short as 25fs, as commonly available at most of the high power laser facilities worldwide, only result in blurred images due to temporal averaging. To overcome this challenge, a few cycle probe beam was developed for the JETI laser system operated at the Institute of Optics and Quantum Electronics in Jena, Germany. This probe pulse was used to track the evolution of the plasma wave with unprecedented spatial and temporal resolution. The transition from the non relativistic oscillation of the electrons inside the plasma wave to a highly relativistic regime with spatial features so far only seen in PIC simulations was observed. Essential characteristics for the laser plasma interaction could be derived by characterizing the transformation of the plasma wave during wave breaking and subsequent electron injection, which form the basis for a future optimization of the acceleration process.

Speaker: Alexander Sävert (Friedrich Schiller University of Jena, Helmholtz Institute Jena)

18:25 3D reconstruction of electron trajectories in a LWFA using spectrally and spatially resolved Betatron radiation

Experiments performed using the 200 TW Callisto laser system at LLNL to produce GeV-class electron beams and keV Betatron x-rays are reported. The laser was focused into various gas cells with sizes ranging from 3 to 10 mm that contained a mixure of gases (He, N, Ar). We demonstrate that it is possible to reconstruct tomographycally electron trajectories inside the channel of the laser-wakefield accelerator fom the angular dependence of the Betatron x-ray spectrum, using an image plate-based spectrometer with differential filtering. Experimental results are benchmarked against a code that solves the equation of motion of electrons oscillating in the plasma wake and by calculating the corresponding x-ray radiation spectrum and profile. This combined single-shot, simultaneous spectral and spatial x-ray analysis allows for a 3D reconstruction of electron trajectories in the plasma with micrometer resolution.

Speaker: Dr Felicie Albert (Lawrence Livermore National Laboratory)

18:50 High sensitivity gas-density profilometry for laser- and beam-driven plasma acceleration experiments

Precise tailoring of plasma-density profiles in longitudinal and transverse direction has been identified to be one of the critical points in achieving stable and reproducible conditions in plasma wakefield accelerators. Here the especially strict requirements of next generation plasma-wakefield concepts, such as hybrid-accelerators, with densities around 10^17 cm-3 pose challenges to target fabrication as well as to their reliable diagnosis. In addition, target complexity has to be minimized to increase reliability for fail-safe accelerator operation. To tackle these issues we combine target simulation with fabrication and characterization. Our target concepts are based on capillaries and gas-cells with multiple gas in- and outlets. The resulting density profiles within are simulated with the fluid code OpenFOAM. Successful simulation results then are followed by fabrication of the desired target shapes with structures down to the few micrometer level. The corresponding longitudinal density profiles at different number densities are measured and benchmarked against the simulation utilizing Raman scattering and longitudinal interferometry, which in combination allow for high sensitivity and thus absolute calibration of targets down to the 10^17 cm-3 regime.

Speaker: Dr Lucas Schaper (University Hamburg / DESY)

Slides 18_50_Schaper.pdf

20:30 → 21:30 Social Dinner

Thursday, 6 June

08:30 → 10:30 Plenary 7

Convener: Vitaly Yakimenko (BNL)

08:30 Novel Accelerators in Asia

Speaker: Prof. Chuanxiang Tang (Tsinghua University)

Slides CTang-An_overview_of_the_novel_accelerator_research_in_Asia_04.pptx

09:10 Advanced Accelerator Activity in Russia

Speaker: Dr Igor Kostyukov (Institute of Applied Physics RAS)

Slides Kostyukov-advanced_accelerator_in_russia1.pdf

09:40 New Collider Concepts for Particle Physics

Speaker: Marco Zanetti (CERN)

Slides EAAC2013_zanetti.ppt

10:10 The European Network for Novel Accelerators (EuroNNAc)

The European Network for Novel Accelerators (EuroNNAc) is part of the European Accelerator R&D (EuCARD2) project and aims at providing a forum for discussion and coordination of advanced accelerator R&D in Europe. Presently it has 52 member institutes with a majority from Europe but also strong links to American and Asian research leaders. The talk will discuss the role that EuroNNAc can play in bringing advanced accelerator technology to users in fundamental and applied science.

Speaker: Dr Ralph Assmann (DESY)

Slides 2013-06-06-rwa-euronnac2_out_v2.pptx 2013-06-06-rwa-euronnac2_out_v3.pptx

10:30 → 11:00 coffee break

11:00 → 12:40 Plenary 8

Convener: Dr Bernhard Holzer (CERN)

11:00 Future Linear Colliders

In the European Strategy for Particle Physics the possible implementation of ILC in Japan for detailed Higgs studies in the near future, and development of CLIC technology for potential use in a machine at CERN after LHC, are both high-lighted. The newly established world wide Linear Collider Collaboration pursue both there objectives and technologies. The status, goals and immediate plans for these projects will be reviewed, with a special emphasis on the European efforts and capabilities in these projects.

Speaker: Steinar Stapnes (CERN)

Slides Stapnes.pptx

11:40 What can we do with a 5 PW laser?

Laser plasma acceleration of electrons has progressed along with laser technology advances. It is thus expected that the development in the near-future of multi-PW-class laser and facilities world-wide will enable a vast range of scientific opportunities for laser plasma acceleration research. On one hand, high peak powers can be used to explore the extremely high intensity regime of laser wakefield acceleration, producing for example large amounts of electrons in the GeV range or generating high energy photons. On the other hand, the available laser energy can be used in the quasi-linear regime to create accelerating fields in large volumes of plasma and study controlled acceleration in a plasma stage of externally injected relativistic particles, either electrons or positrons. After a general description of the key topics that can be addressed using multi-PW laser, examples of studies planned in France will be given. In the frame of the Centre Interdisciplinaire de la Lumière EXtrême (CILEX), the Apollon laser will deliver two PW level, ultra-short (>15fs) pulses to a target area dedicated to electron acceleration studies, such as the exploration of the non-linear regimes predicted theoretically, or multi-stage laser plasma acceleration.

Speaker: Dr Brigitte CROS (LPGP-CNRS-UP11)

Slides Cros.pdf

12:10 Coherent Diffraction Imaging - a Novel and Promising Tool to Investigate Non Crystalline Matter at Atomic Resolution

Speaker: Cinzia Giannini (CNR - Institute of Crystallography)

Slides EAAC_2013_Giannini.ppt

12:40 → 16:00 lunch

16:00 → 17:30 Summary Session 1

Convener: Prof. Simon Hooker (University of Oxford)

16:00 WG1 Summary

Speakers: Prof. Patric Muggli (Max-Planck-Institut für Physik), Prof. Zulfikar Najmudin (Imperial College London)

Slides EAACsummary_1_NAJMUDIN.pdf

16:30 WG2 Summary

Speaker: Prof. julien fuchs (luli-cnrs)

Slides WG2_Summary.pdf

17:00 WG3 Summary

Speaker: Dr Manoel Conde (Argonne National Laboratory)

Slides Working_Group_3_Summary.pptx

17:30 → 18:00 coffee break

18:00 → 19:30 Summary Session 2

Convener: Massimo Ferrario (LNF)

18:00 WG4 Summary

Speaker: Prof. Andrei Seryi (John Adams Institute for Accelerator Science)

Slides EAAC-WG4-Summary-A-Seryi-r1.pptx

18:30 WG5 Summary

Speakers: Alessandro Cianchi (ROMA2;LNF), Dr Jens Osterhoff (Deutsches Elektronen-Synchrotron DESY)

Slides WG5_summary_part2.pdf

19:00 WG6 Summary

Speaker: Luis O. Silva (Istituto Superior Técnico, Lisboa)

Friday, 7 June

08:30 → 19:00 EuroNNAc Meeting

Convener: Dr Ralph Assmann (DESY)

08:30 Approval of Agenda

08:40 Introduction of Participants

09:00 European Strategy for Particle Physics - What Does it Mean for Us?

Slides European_Strategy_Draft_ESG_Proposal.pdf

09:30 Short Status and Plans at Institutes, if not reported at EAAC

(1 report per institute, verbal or 3 slides max, round-table)

10:30 Coffee Break

11:00 What Could a European Distributed R&D Facility for Novel Acc. Do for Us?

(How could it look like? How many centres with which type of focus do we need?)

Slides 2013-06-07_euronnac_assmann.ppt

12:30 Lunch

16:00 Review of Network Goals and Discussion of Network Plans up to 2016

Slides euronnac2012-outcome-out_v21-06-2012.xlsx euronnac-2012-out.docx

18:00 AOB

18:30 Close-Out