Seminari 2015

1 Jan 2015, 08:00 → 31 Dec 2015, 18:00 Europe/Rome

stanza 412, blocco C (Dipartimento di Fisica e Scienze della terra)

Stefania Vecchi (FE)

Lista dei seminari di Fisica del Dipartimento di Fisica e Scienze della Terra e della sezione INFN di Ferrara

Thursday 29 January

1 Renaissance in Astrophysics: the primordial stars

Abstract The last « Terra incognita » of our Universe is usually called the dark age. It ends with the most powerful fireworks of the universe: the creation of the first stars. With them our Universe changes drastically. According to theoretical models, massive stars with masses within the 100- 250 solar mass range should explode as pair-instability supernovae (PISNe). Since the first stars of the Universe are believed to be very massive, these supernovae should play a signicant role in the early stages of its history. But these stars represent the last unobserved population, owing to detection limits of current telescopes. In this presentation, we analyze pair-instability supernovae explosions using various numerical codes. We evolve series of configurations of oxygen cores to establish a range of masses and initial conditions where this type of explosion is possible. We also study the role of possible instabilities in the propagation of shockwaves during the last stage of the explosion. This investigation could help us to predict the observational properties of PISNe for future space and ground telescopes and the possible connections with Gamma-Ray Bursts

Speaker: Prof. Pascal Chardonnet (Université de Savoie, Annecy (France))

Monday 2 February

2 Ultra-sensitive length measurement: Gravitational wave detectors and what they might be good for.

A world-wide effort is under way to make the first direct detection of gravitational waves, which were predicted by Einstein a century ago. The establishment of gravitational wave astronomy is expected to follow. Gravitational waves are distortions of space-time, travelling at the speed of light, which can be detected with ultra-sensitive length measurements. I will introduce the basic functionality of laser interferometers built for this purpose, which are able to measure length fluctuations 100000 times smaller than the diameter of a proton. I will further give an overview of the different detectors around the globe. In the last third of the talk I will present recent thoughts on how these gravitational wave detectors might be used to also attempt a measurement of vacuum birefringence.

Speaker: Hartmut Grote (Albert Einstein Institute (MPI) Hannover)

Thursday 19 February

3 Running in the Dark: numerical simulations of non-standard Dark Matter and Dark Energy cosmologies

Structure formation represents one of the most promising observational targets to shed some light on the longstanding mysteries about the composition of about 95% of the energy density in the Universe. In fact, although the standard cosmological picture - the LCDM model - provides a simple framework to encompass most of the available data, the fundamental nature of its main pillars (the cosmological constant Lambda and the Cold Dark Matter particle) is still unknown and its theoretical foundations suffer from multiple "naturalness" problems. In such a context, a wide range of possible alternative theories for both the Dark Energy and the Dark Matter components of the Universe have been proposed. A systematic and robust scrutiny of such wide landscape of non-standard cosmological models can be performed only by combining information from both linear and non-linear scales, thereby requiring the use of numerically demanding computer simulations. In this talk I will provide a general overview on numerical simulations of structure formation in non-standard cosmological models. I will then discuss a few key results obtained with some of the largest N-body runs to date for various popular cosmological models beyond LCDM, as e.g. the interacting Dark Energy, Modified Gravity, and Dark Scattering scenarios. Finally, I will discuss how the issue of Cosmic Degeneracies (i.e. the combined effects of multiple and mutually independent extensions of the standard model) might significantly degrade the discriminating power of present and future cosmological surveys. In particular, the combination of "reasonable" non-standard models for both Dark Energy and Dark Matter might conspire to substantially mask their individual observational footprints. Breaking such possible degeneracies represents a new challenge on our path towards percent precision measurements in cosmology.

Speaker: Marco Baldi (Universita-INAF-INFN Bologna)

Wednesday 25 February

4 The JUNO experiment: entering the era of precision neutrino physics

The first unexplained evidence of neutrino oscillation dates back to the late 60s, and it took more than 30 years before the SNO experiment solved the Solar Neutrino Problem by proving the existence of neutrino flavor change. Nowadays we know many of the neutrino mixing parameters with a precision of few percent, but several theoretical issues are still waiting to be settled. Determining the neutrino mass hierarchy and probing the unitarity of the PMNS matrix are among the most important ones. The JUNO experiment is a liquid scintillator detector aiming at collecting a large (O(105)) sample of antineutrinos from reactors at a baseline of 53km. Its unprecedented target mass (20kt), photo-coverage (75%), and light yield make it a high resolution (3%/√E) antineutrino calorimeter, sensitive to the interference between the solar and the atmospheric mass splittings. Such sensitivity is the gateway to finally determine the neutrino mass hierarchy and to push the uncertainties of sin2(θ12), Δm212 and Δm223 below 1%, hence moving the first steps towards probing the PMNS unitarity. The seminar focuses on both the scientific goals and the experimental challenges of the JUNO experiment, providing also some insight into the R&D activities and the fast-growing international collaboration.

Speaker: Marco Grassi (PI)

Thursday 26 February

5 Theoretical and phenomenological considerations about radiation by relativistic electrons in matter or in external fields

Most known examples of radiation by relativistic electrons in matter, near matter or in external field are 1) Bremsstrahlung, Synchrotron Radiations, 2) Channeling, Transition, Diffraction, Smith-Purcell Radiation, Parametric X-rays and Compton back-scattering. Their common and separate properties and their calculation methods are reviewed, in particular : coherence length, infrared divergence, equivalent photon picture, quantum recoil in strong QED fields, Baier-Katkov formula, photon impact parameter.

Speaker: Xavier Artru (Université Lyon-1, CNRS/IN2P3, IPNL)

6 Invarianza T ( inversione temporale ) in meccanica classica e quantistica

Si studiano le proprietà dell'operatore T in meccanica classica e quantistica ( livello laurea triennale )

Speaker: Prof. Luca Caneschi (Universita' di Ferrara)

7 Invarianza T in teoria dei campi e fisica delle particelle

Si studiano le proprietà dell'operatore T in teoria dei campi e in fisica delle particelle. Si esamina la situazione sperimentale relativa alla possibile rottura di T ( livello laurea magistrale- dottorato )

Speaker: Prof. Luca Caneschi (Universita' di Ferrara)

Tuesday 3 March

8 La biofisica di un fisico (ma anche di altri soggetti…)

Quali sono i meccanismi fisici alla base della formazione dei segnali elettrici nei neuroni, i quali, connessi tra loro opportunamente, formano una rete (il sistema nervoso) in grado di percepire il mondo esterno, di interpretarlo, di ricordarlo, di sognarlo, di raccontarlo ad altre reti, conscia di farlo? E a che le serve saperlo?

Speaker: Giorgio Rispoli (Universita' di Ferrara, Dipartimento di Scienze della Vita e Biotecnologie)

Monday 16 March

9 Phenomenology of low-energy flavour models: rare processes and dark matter

In this seminar, I will first review the main features of models of fermion masses and mixing based on new symmetries of flavour. I will then discuss how light the new flavour dynamics is allowed to be by the constraints from flavour-changing processes and possible UV completions of this kind of models. In the second part of the seminar, I will introduce dark matter (DM) as a fermionic singlet under the Standard Model (SM) gauge group that is however charged under the flavour symmetry. Interactions between DM and SM particles are then only mediated by the scalar fields that spontaneously break the flavour symmetry, the so-called flavons. In the case of gauged flavour symmetries, the interactions are also mediated by the flavour gauge bosons. I will discuss the construction and the generic features of this class of models and then the phenomenology of an explicit example.

Speaker: Lorenzo Calibbi (Universita' di Bruxelles)

Tuesday 24 March

10 New limits on non-linear QED and axions from the PVLAS experiment

A new highly sensitive ellipsometer is now running at the Department of Physics and INFN of Ferrara, Italy. The apparatus has been designed to detect very small magnetically induced birefringences with the ultimate goal of measuring vacuum magnetic birefringence, an effect directly related to light-light interaction. This challenging goal is not yet achievable due to excess noise which is under study. Nonetheless a new limit on vacuum magnetic birefringence has been recently set. Taking advantage of the cavity intrinsic birefringence, our ellipticity limit can also be used to set a dichroism limit. From these two values we also set model independent limits on the coupling constant of axion like particles to two photons.

Speaker: Guido Zavattini (Universita' e INFN Ferrara)

Wednesday 25 March

11 Silicon Pore Optics: from the Athena mirrors to Laue lenses

Silicon Pore Optics (SPO) is a technology based on direct bonding of super-polished Si plates that enables lightweight and accurate Wolter-I type X-ray optics. Developed by Cosine, SPO has been adopted by the European Space Agency for the Athena mission, allowing the realization of its 2 m^2 effective area (at 1 keV) and 3-5 arc seconds angular resolution in a 0.1-15 keV bandpass. At higher energy, in the soft gamma-ray domain, a Laue lens telescope could efficiently complement wide field of view instruments by providing enhanced sensitivity and angular resolution in a selection of relatively narrow energy bands. Cosine, in collaboration with the University of California at Berkeley, has been developing the first Silicon Laue Components (SiLCs), a concept directly derived from the SPO technology. It results in self-standing diffracting elements that focus both radially and azimuthally. I will first review the SPO concept and present the state of the art of its development, and I will then present the development status of SiLCs, and refined estimates of the performance they could deliver based on experimental results.

Speaker: Nicolas Barriere (Scientist - X-ray optics Specialist, Cosine Measurement Systems, Leiden, The Netherlands)

Thursday 9 April

12 "Gamma Ray Burst Physics with the Liverpool Telescope and LCOGTN"

I will review recent results of the international team using the Liverpool Telescope and the LCOGTN to observe GRBs’ optical afterglows to study their behaviour in the first minutes to hours after the GRB trigger, thus shedding the light on their physics. Rapid multi-band photometric observations in combination with high-energy data from satellites reveal origin of optical flares occurring contemporaneously with prompt gamma-ray emission and enable statistical studies of GRBs with and without the reverse shock optical emission. However, one of the most important questions of GRB physics is the role of the magnetic field, which can be addressed by measuring linear polarisation of an early optical afterglow. Using the RINGO 2 polarimeter on the Liverpool Telescope we showed in the case of the GRB 120308A that large scale ordered magnetic fields are present in these explosions.

Speaker: Andreja Gomboc (Faculty of Mathematics and Physics, University of Ljubljana, Slovenia)

Friday 10 April

13 Now you see it, now you don’t - the rapid cycle of BH accretion phases

The study of AGN variability on timescales longer than human lifetimes can provide important information about the black hole – host galaxy interaction and coevolution. The discovery of an extended emission line region (EELR) associated with the nearby galaxy IC 2497, the so-called “Hanny’s Voorwerp” (HV), provided us with a laboratory to study AGN variability over 100 kyr timescales. HV was illuminated by a strong quasar, but the quasar in IC 2497 significantly shut down in the last 200 kyrs. Thanks to its recent death, we can now explore the host galaxy unimpeded by the presence of a quasar dominating the observations. On the other hand, the Voorwerp preserves the echoes of its past activity. Citizen scientists taking part in the Galaxy Zoo project assembled a sample of low-redshift galaxies showing EELRs similar to HV. In this talk I will show how these objects can help us understand what happens when a quasar shut down and its accretion state changes, and ultimately what effect this could have on the host galaxy.

Speaker: Lia Sartori (ETH Zürich (Institute for Astronomy))

Monday 13 April

14 PADME: ricerca di dark photons alla BTF di Frascati

Molte estensioni dello Standard Model prevedono particelle vettoriali (bosoni U o fotoni pesanti o dark photons) con interazioni simili a quelle dei fotoni, che possono essere prodotte in associazione ai fotoni. L’esperimento PADME si propone di cercare tali particelle in processi e+e−→Uγ, U→invisibile nell’interazione di un fascio di positroni con gli elettroni di un bersaglio sottile, utilizzando il fascio del linac di DAFNE estratto sulla linea della Beam-Test Facility (BTF) ai Laboratori Nazionali di Frascati, INFN. Conoscendo l'impulso del fascio incidente e misurando con precisione quello del fotone con un calorimetro opportunamente segmentato, è possibile chiudere la cinematica e effettuare una ricerca model-independent studiando la massa mancante. Per questo tipo di ricerca inclusiva non esistono, ad oggi, risultati sperimentali. Con il fascio di positroni di 550 MeV attualmente disponibile, sarebbe possibile ottenere un'esclusione della regione fino a 23 MeV di massa e 10^-6 nell'accoppiamento (alpha'/alpha) con un anno di presa dati (4x10^13 eot). Eventuali upgrade in energia del linac sarebbero utili a estendere la sensibilità dell’esperimento. Per sfruttare la produzione di dark photon in processi di Bremsstrahlung ed il loro successivo decadimento in coppie di leptoni U → e+e− l'esperimento viene completato da uno spettrometro magnetico. E' possibile migliorare le esclusioni attuali anche estraendo il fascio del linac alla massima intensità su un bersaglio spesso tipo dump. Si puo' cercare sia l'apparizione di coppie di leptoni dopo i dump, sia lo scattering con i nuclei di particelle di dark matter leggere derivanti da decadimenti invisibile del dark photon in un rivelatore dedicato.

Speaker: Paolo Valente (ROMA1)

Tuesday 28 April

15 The First Cosmological Simulations of Coherent Bosonic Dark Matter for the "Post-WIMP Era"

Heavy particles are not the only interpretation for the observed coldness of dark matter - here I present cosmological simulations of a cold Bose-Einstein state, revealing an unknown world of non-linear wave structures that distinguish this physically well motivated state from standard particle CDM. The key predictions are made with GPU optimised AMR evolution of coupled Schrodinger-Poisson equations, finding solitonic cores and a granular structure within virialised halos. Comparison with the latest Hubble Frontier Field galaxies that we have detected at high redshift favours this interpretation, as do the large cores derived for dwarf galaxies and by QSO flux anomalies. This exploration is timely because of the continued laboratory absence of WIMPs, and may establish light bosons as the most viable interpretation of dark matter.

Speaker: Tom Broadhurst (University of Basque Country , Bilbao)

Thursday 7 May

16 High redshift cosmography in Dark Energy cosmological models

Cosmography provides information about the evolution of the universe from measured distances, only assuming that the space time geometry is described by the Friedmann-Lemaitre-Robertson -Walker metric, and adopting a Taylor expansion of the scale factor. Our high-redshift analysis allows us to put constraints on the cosmographic expansion up to the fifth order. It is based on the Union2 Type Ia Supernovae data set, the Hubble diagram constructed from some Gamma Ray Bursts distance indicators, and gaussian priors on the distance from the Baryon Acoustic Oscillations, and the Hubble constant. The estimation of the higher order cosmographic parameters reflect the possibility of a deviation from the ΛCDM model. Moreover we investigate implications of our results for the parametrization of the dark energy equation of state. Finally we investigate the implications of the cosmographic analysis within the so called curvature quintessence scenarios. Our interest is actually focused on fourth order theories, based on replacing the scalar curvature R in the Hilbert-Einstein action with a generic f(R)

Speaker: Ester Piedipalumbo (Universita di Napoli Federico II)

Tuesday 12 May

17 Geoneutrinos and heat production in the Earth

Geo-neutrinos, produced during beta decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planets interior. The kTon-scale, underground, liquid scintillation detectors in Japan and Italy, which measure the flux of these electron anti-neutrinos, reveal that radiogenic heat from the decay of Th and U (only detectable signal) contributes between 20% and 50% of the Earth's present-day power (46+/-3 TW). These particle physics experiments are now establishing limits on acceptable compositional models for the Earth and are defining the amount of nuclear power inside the Earth available to drive plate tectonics, mantle convection, and the geodynamo.

Speaker: Prof. William F. McDonough (Maryland University)

Tuesday 19 May

18 Reconciliation of hemispherical asymmetry and power suppression in the CMB

The recent measurements of temperature and polarization of Cosmic Microwave Background (CMB) have improved our understanding of the Universe and have showed a remarkable agreement with the ΛCDM cosmological model. However, scale dependent features like power suppression in the angular power spectrum, hemispherical asymmetry in the temperature field of CMB and direction dependent spectral index, indicate possible departure from the ΛCDM model persist in the CMB data. Speaker will discuss a mechanism linked to possible initial inhomogeneities in the inflationary scalar field that could explain all these observed phenomena. Initial inhomogeneities lead to non-zero values of anisotropic inflationary parameters, which at leading order cause different amounts of hemispherical asymmetry in the scalar and tensor perturbations. The second order effect of anisotropic inflationary parameters naturally lead to a suppression (enhancement) of power at low multipole l for scalar (tensor) perturbations. As a result this model unifies both the large angular scale features like suppression of power and hemispherical asymmetry by a single phenomenon. Along with this, the model also predicts a direction dependent spectral index, consistent with the direction of hemispherical asymmetry. The salient feature of this model is that it produces all the effects in tensor and scalar perturbations by just two independent parameters and future missions can measure these parameters uniquely and hence the validity of the model can be investigated.

Speaker: Suvodip Mukherjee (IUCAA, India)

Wednesday 27 May

19 Glueballs and other exotic states in QCD

Non-conventional mesons, such as glueballs, tetraquarks as well as dynamically generated states, are in the center of theoretical and experimental studies of low-energy QCD. In this talk we review some basic properties of QCD in connection to the emergence of unconventional states. Then, we focus on the search of the expected not-yet discovered glueballs and the use of the extended Linear Sigma Model for this purpose, and on already discovered but not-yet understood states: the light scalar mesons below 1 GeV as well as the newly found heavy X,Y,Z states.

Speaker: Francesco Giacosa (Jan Kochanowski University, Kielce, Poland.)

Thursday 4 June

20 Development of Electron Tracking Compton Camera (ETCC) for a Survey of the Deep Universe by MeV gamma-rays

ETCC with a gas Time Projection Chamber (TPC) and pixel GSO scintillators, by measuring electron tracks, provides both a strong background rejection by dE/dx of the track and clear imaging by adding the arc direction of incident gammas (SPD: Scatter Plane Deviation) with the ARM (angular Resolution Measure) direction measured in standard Compton Camera (CC). In 2006 its background rejection was revealed by SMILE-I balloon experiment with 10cm-cubic ETCC using the dE/dx of tracks. In 2013, 30cm-cube-ETCC has been developed to catch gammas from Crab in next SMILE-II balloon with >5sigma detection for 4 hrs. Now its sensitivity has been improved to 10sigma by attaining the angular resolution of the track (SPD angle) to that determined by multiple scattering of the gas. Thus, we show the ability of ETCC to give a better significance by a factor of 10 than taht of standard CCs having same detection area by electron tracking. Based on this technology, SMILE-II with 3atm CF4 gas is expected to provide a 5times better sensitivity than COMPTEL in one month balloon, and 4modules of 50cm-cube ETCCs would exceed over 10^-12 erg/cm^2s^1 (1mCrab) in satellite. To verify its perfomance in space, SMILE-II was irradiated by intense gammas and neutron using 140MeV proton, and successfully measured both clear image of a weak RI without the efficiency deterioration under 10times stronger radiation than the space. Here we summarize the performance of the ETCC and new astrophysics opend in near future by high sensitive observation of MeV gamma-rays.

Speaker: Prof. Toru Tanimori (Department of Physics, Kyoto University, Kyoto, Japan)

Monday 29 June

21 The world turned upside-down: a story from the oceans’ underworld where life, matter and energy come from the earth’s interior

It has been only a few decades since scientists have discovered that life at the surface of our planet and in oceans is just a fraction of the global biomass. Indeed, a large portion of life on Earth could occur beneath the oceans’ abyss, within marine sediments. In these ‘extreme’ environments, there is no sunlight, nor oxygen, and pressures are extremely high. Yet, it is the habitat of unicellular organisms, the simplest of all life forms, which can survive by ‘breathing’ chemicals carried by the interstitial fluids, fossil organic matter, hydrogen and methane. Our present understanding of deep microbial life, its extent and relationships/interactions with the subsea floor largely derive by deep-sea drilling science programs (e.g. IODP) that allow directly sampling and studying these buried environments. Deep subsea floor life has been also documented at the ocean bottom in deep hypersaline anoxic basins and mud volcanoes, which, unlike traditional volcanoes, are driven by chemistry and not heath.

Speaker: Ivano Walter Aiello

Wednesday 8 July

22 Light (anti)(hyper)nuclei production in Pb-Pb collisions

The high collision energies reached at the LHC lead to significant production yields of light anti- and hyper-nuclei in proton-proton and, in particular, Pb-Pb collisions. Thanks to its excellent particle identification capability, the ALICE detector allows for the identification of deuterons, $\rm ^{3}{He}$ and $\rm ^{4}{He}$ and their corresponding antinuclei. This is achieved via the measurement of their specific energy loss in the Time Projection Chamber and of their velocity by the Time-Of-Flight detector. Moreover, thanks to the Inner Tracking System ability to separate primary from secondary vertices, it is possible to identify (anti)hypertritons ($\rm ^{3}_{\Lambda}{H}$) exploiting their mesonic weak decay ($\rm ^{3}_{\Lambda}{H}$ $\rightarrow$ $^{3}\rm{He}$ + $\pi^-$) and to search for a hypothetical bound state of a $\Lambda$ with a neutron decaying into a deuteron and a pion. Results on the production of light nuclei and anti-nuclei in Pb--Pb and lighter collision systems (pp and p--Pb) will be presented. Hypernuclei production rates in Pb--Pb will also be shown, together with a measurement of the hypertriton lifetime and upper limits estimated on the production of lighter exotica candidates. The experimental results will be compared with the predictions of both thermal (statistical) and baryon coalescence models.

Speaker: Ramona Lea (TS)

Tuesday 14 July

23 A brief summary of a few astro-statistical projects

Five non-standard statistical problems, posed by astronomical observations, are described. These include: the upper limit on stellar masses; testing whether Cepheid pulsating stars in different galaxies are similar; and dis-entangling very weak periodic pulses from different sources, when the sources cannot be resolved. No expertise in either astronomy or statistics will be assumed.

Speaker: Chris Koen (University of Cape Town)

Tuesday 29 September

24 ULA‐OP: caratteristiche ed applicazioni non convenzionali di una piattaforma di ricerca ad ultrasuoni

Negli ultimi anni, la ricerca sperimentale con ultrasuoni ha avuto grande impulso grazie allo sviluppo dei cosiddetti sistemi aperti (open scanners), vere e proprie piattaforme di ricerca che permettono il test di modalità di Imaging e Doppler non convenzionali. In questo seminario sarà presentata l’esperienza maturata nel nostro Laboratorio con il progetto e la realizzazione del sistema ULA‐OP (ULtrasound Advanced Open Platform). Tale sistema si caratterizza, oltre che per le piccole dimensioni ed il costo contenuto, per l’estrema flessibilità che ne permette l’uso in numerose applicazioni non compatibili con gli scanner commerciali. Dopo aver illustrato brevemente le caratteristiche generali del sistema e le possibili modalità di programmazione, saranno presentati alcune modalità avanzate di formazione di immagini (ad esempio, attraverso l’uso di onde piane) e di indagine flussimetrica Doppler (ad esempio, Doppler vettoriale in tempo reale).

Speaker: Piero Tortoli (Laboratorio Progettazione sistemi microelettronici (MSDLab) Dipartimento di Ingegneria dell’Informazione Università degli Studi di Firenze)

Wednesday 21 October

25 Gravitational waves and heavy elements from neutron-star mergers

Collisions of neutron stars are connected with a rich phenomenology. For instance, matter which becomes gravitationally unbound from the merger site, is very neutron-rich and expands with very high velocities. This provides favorable conditions for the formation of heavy elements by the rapid neutron-capture process. These nucleosynthetic processes heat the ejecta and lead to a possibly observable electromagnetic counterpart. In addition, neutron-star mergers are strong emitters of gravitational radiation, and thus one of the prime targets of the existing and upcoming gravitational-wave detectors. Since the dynamics of the merger are affected by the unknown high-density matter equation of state, also the gravitational-wave signal is equation of state dependent. This, in turn, offers the possibility to derive properties of the equation of state from gravitational-wave detections.

Speaker: Andreas Bauswein (Heidelberger Institut fuer Theoretische Studien, Heidelberg, Germany)

Thursday 5 November

26 Magnetars and binary systems

I review several scenarios of magnetar formation in binary systems via spinup of a progenitor due to interaction with its companion. Mostly, these evolutionary channels lead to formation of isolated magnetars, and indeed, all well-established sources of this class are single objects. However, some binaries can survive, and several candidates to accreting magnetars have been proposed. I discuss this issue, and conclude that new accretion models can explain properties of the proposed candidates without large magnetic field in correspondence with models of magnetic field evolution.

Speaker: Serguei Popov (Sternberg Astronomical Institute, Lomonosov Moscow State University)

Monday 30 November

27 Unsolved puzzles of Gamma Ray Bursts

Speaker: Alexei Pozanenko (Space Research Insitute (IKI, Moscow))

Thursday 3 December

28 The magnetar model for GRBs.

Recent observations of late time activity both in Short and long GRBs, have strengthen the idea that a long lived engine is at work. A possible rapidly rotating strongly magnetized proto-neutron star looks at the moment the best candidate to explain this class of highly energetic explosions. I will briefly review the main properties of GRB, and the strength of the magnetar model, and numerical results relating the birth of magnetized NS and their impact of the SN explosion, and the competition between EM and GW losses. I will also discuss possible limitations and recent attempts to extend the magnetar idea to connect GRBs with the standard population of SNe.

Speaker: Niccolò Bucciantini (Osservatorio di Arcetri)

Thursday 10 December

29 X-ray binaries and Ultra-luminous X-ray sources

All known to date stellar mass black holes reside in X-ray binaries (XRB). They are connected with a number of uncommon phenomena like mass transfer, state transitions, and relativistic jets. Analysis of XRB gives us insights in their formation mechanism and particularly the origin of compact objects. Probably, their most interesting feature is the "the mass gap" (i.e., the lack of compact objects with masses ~2-5 MSun). This observation is a stringent test for compact object formation mechanism. Ultraluminous X-ray sources (ULX) are the strongest point-like X-ray sources known to date. The high energetic emission seems to be a hallmark of violent interactions between a strong gravitational field and matter. Recent works showed a strong resemblance between ULXs and XRBs suggesting that they may constitute the extreme part of their population. We know several hundred ULXs which could prove to be the marvelous laboratories of extreme processes.

Speaker: Grzegorz Wiktorowicz (Universita di Varsavia)

Friday 11 December

30 Deflection of high-energy charged particle by a bent crystal

When a high-energy charged particle impinges on a crystal with a small angle with respect to one of the main crystallographic axes, correlations between consecutive collisions of the particle with lattice atoms appear. Due to these correlations and strong intra-crystalline fields, the direction of the particle motion can be changed within quite small distances. The passage of high-energy charged particles through a bent crystal is of particular interest because, in this case, it is possible to deflect the direction of motion of charged particle beam with a small-sized crystal. There are several mechanisms of deflection of high-energy charged particles by a bent crystal connected with finite (channeling) and infinite (above barrier) motion in relation to bent atomic strings or bent crystal atomic planes. These mechanisms are realized in the planar and axial channeling in a bent crystal, in the stochastic mechanism of beam deflection (connected with multiple scattering by bent crystal atomic strings) and volume reflection from bent crystal atomic planes. The main point of this seminar is comparison of these mechanisms.

Speaker: Igor Kirillin (Akhiezer Institute for Theoretical Physics, Kharkov, Ucraina)

Thursday 17 December

31 An experience of using OpenCL for simulation of high-energy charged particle motion in a crystal

The Open Computing Language (OpenCL) is an open parallel computing API designed to enable GPUs and other coprocessors to work in tandem with the CPU. It is cross-platform and royalty-free standard. The main point of this seminar is to tell about the experience of using OpenCL for parallelization of computing the trajectories of high-energy charged particles in a crystal. If the crystal is rather small interaction of the particles with each other can be ignored and so the trajectories of particles can be calculated in parallel. This gives acceleration of computations proportional to the number of computing units of CPU and GPU.

Speaker: Igor Kirillin (Akhiezer Institute for Theoretical Physics, Kharkov, Ucraina)

Friday 18 December

32 Neutrino Oscillation Tomography

The unknown constituents of the interior of our home planet have provoked the human imagination and driven scientific exploration. In the near future it might be possible to determine the Earth’s chemical composition by combining observations from large neutrino detectors with seismic measurements of the Earth’s matter density and data from high pressure experiments. The talk will introduce this novel method and discuss its potential. Neutrino detectors including the IceCube Neutrino Telescope, which recently discovered high-energy astrophysical neutrinos, will be introduced and future detector upgrades which could perform a first neutrino oscillation tomography measurement discussed.

Speaker: Carsten Rott (Sungkyunkwan University, Korea)