Search

Compton camera is a radiation detector that uses the kinematics of Compton scattering to estimate the direction of the gamma-ray incident. Compton camera has been used in many applications such as astronomy, medical, nuclear industry, and security. High time resolution in a Compton camera is essential to distinguish the incoming event in the detector. In this work, we developed a Compton camera using a fast decay scintillator and a high time resolution front end circuit to get a high-performance detector. The detector used an 8×8 multi-pixel photon counter (MPPC) array, which individually couple with a 2.5×2.5×5 mm3 GFAG (Gadolinium Fine Aluminum Gallate) scintillator. For processing the analog signal from the MPPC scintillators, the 64 channel ASIC (Application-Specific Integrated Circuit) is used. Each channel in the ASIC circuit consists of a pre-amplifier, shaper, monostable multivibrator, and slew-rate time over threshold. The ASIC will provide the digital output signal that contains the timing and energy information. The high-time resolution data acquisition circuit (PETnet) based on FPGA is used to acquire energy and time data from ASIC. [ABSTRACT FROM AUTHOR]

We present recent results on the extraction of the static scalar dipole polarizabilities (αE1 and βM1) from proton real Compton scattering (RCS) data below pion-production threshold. We focus on the fitting technique that is based on the parametric bootstrap. We show how to compute the realistic p-values, even when correlated and/or systematic uncertainties are present. We use the theoretical framework provided by fixed-t subtracted dispersion relations, which are obtained from the unitarity, causality and analyticity constraints of the RCS amplitudes. We obtain the numerical results: α E 1 = 12.03 − 0.54 + 0.48 , β M 1 = 1.77 − 0.54 + 0.52 (in 10−4 fm3 units), with p-value = 12%. Thanks to the new fitting technique, we are able to include in the data analysis both the systematic uncertainties and the experimental error of those parameters that are taken as input. [ABSTRACT FROM AUTHOR]

Deeply Virtual Compton Scattering (DVCS) is the simplest exclusive process to access Generalized Parton Distributions (GPDs). GPDs encode the correlation between the spatial distribution of partons inside the nucleon and their momentum. An upcoming DVCS experiment in Hall C at Jefferson Lab (Virginia, U.S.A.) will provide the highest precision data in a vast Q2-xB region accessible by an 11 GeV electron beam. It will further test the leading-twist dominance of the observables and get more precise data in the lower xB region needed for the full mapping of GPDs. A Neutral Particle Spectrometer (NPS) is being developed for this experiment. It consists of an electromagnetic calorimeter made of 1080 PbWO4 crystals and a sweeping magnet. This document will present the status of the detector R&D and construction, as well as simulation results of its performance. [ABSTRACT FROM AUTHOR]

We report current status of the LEPS2 solenoid spectrometer for photoproduction experiments at SPring-8. A large solenoid LEPS2 spectrometer consists of a time projection chamber (TPC), drift chambers, resistive plate chambers and Pb/scintillator sampling calorimeters for photoproduction of hadrons in the energy range from 1.4 to 2.9 GeV. We have developed a new, network-distributed data acquisition system based on DAQ-middleware framework. The DAQ middleware components include gatherers collecting data from detector sub-systems, mergers integrating data from gatherers, and an event builder in the data acquisition software. Over ten thousand pad signals from the TPC are digitized with 40 MS 12-bit flash ADCs and then sent to a TPC gatherer through Space-Wire protocol. During the beam commissioning, Compton-backscattered photon beam was incident on a CH2 target in the energy region from 1.4 GeV to 2.4 GeV. We report on the performance test results of the new DAQ system with beam commissioning of the LEPS2 spectrometer as well. [ABSTRACT FROM AUTHOR]

Polarizabilities are fundamental properties related to the internal structure and dynamics of the nucleon. They play a crucial role not only in our understanding of the nucleon, but also in other areas such as atomic physics. The A2@MAMI Collaboration has undertaken a comprehensive program of real Compton scattering experiments in order to accurately determine these parameters at the Mainz Microtron (MAMI), using the Crystal Ball/TAPS setup. A new high quality data-set has been collected both on the differential cross section and on the beam asymmetry Σ3 below the pion production threshold using a polarized photon beam and an unpolarized liquid hydrogen target. This measurement will allow an extraction of the proton scalar polarizabilities αE1 and βM1 with a significant improvement to the large uncertainties of the present values. Moreover, the use of linearly and circularly polarized photon beams in conjunction with polarized targets will also allow an extraction of the different proton spin polarizabilities, which at the moment have only been determined in various linear combinations. To study these, the asymmetries Σ2x, Σ2z and Σ3 were measured above the pion production threshold. [ABSTRACT FROM AUTHOR]

The precise measurements of the Compton scatterings of photons originating from the decay of positronium atoms can reveal information about their polarizations. J-PET detector is constructed of 192 plastic scintillators and is unique to study the scattering correlations of the annihilation photons with an angular precision of several degrees. In this work, we present the first experimental evidence showing the feasibility of measuring the photons relative polarization using the J-PET detector. [ABSTRACT FROM AUTHOR]

This paper is devoted to a plastic scintillator detector calibration method. We calibrated the large volume polystyrene gamma detector SPD200.200.100 by NUVIA Group. The essential issue of the plastic scintillator is that Compton scattering is the dominant effect of photon interaction within the detector and it is no apparent full energy absorption peak in a spectrum. Our approach is based on MCNP code simulation where the detector was modeled. Then measured and calculated spectra are compared to determine the Gaussian energy broadening effect. Finally, the measured spectra can be calibrated using Compton maximum and Compton edge energy. The results of this study show that measured and calculated spectra are in good agreement. [ABSTRACT FROM AUTHOR]

Structural and bonding properties of transition metal carbides TiC and ZrC have been investigated using linear combination of atomic orbitals within framework of density functional theory. Density of states, bulk modulus, lattice parameters and pressure derivatives of the bulk modulus calculated at ground state energy are reported. The structure factors and real space Compton profiles (autocorrelation functions) of these materials are also discussed. The covalent bonding character of both the carbides has been discussed on the basis of structure factors, momentum densities and equal-valence-electron-density profiles. [ABSTRACT FROM AUTHOR]

The hard electroproduction of a photon off a hadron in the Bjorken regime, Deeply Virtual Compton Scattering, unravels three-dimensional information on the partonic structure of the hadron. The imaginary part of the amplitude is more particularly sensitive to the spatial distribution of quarks as functions of the light cone momentum fraction. On the other hand, the real part of the amplitude is less constrained experimentally, and provides access to the D-term. Here we present preliminary results for the extraction of the D-term from unpolarized cross-sections and beam spin asymmetries measured with the CEBAF Large Acceptance Spectrometer at 6 GeV. We discuss some aspects of the associated physics interpretation, and give prospects for future measurements. The availability of a Positron beam at Jefferson Lab will provide access to the Beam Charge Asymmetry for this reaction, which will crucially enable us to keep under control the systematical and model uncertainties in this framework. [ABSTRACT FROM AUTHOR]

We present the first-ever experimental electron momentum density of Ag2CrO4 using 661.65 keV γ-rays from 20 Ci 137Cs source. To validate our experimental data, we have also deduced theoretical Compton profiles, energy bands and density of states using linear combination of atomic orbitals (LCAO) method in the framework of density functional theory. It is seen that the DFT-LDA gives a better agreement with experimental data than free atom model. The energy bands and density of states are also discussed. [ABSTRACT FROM AUTHOR]

We present the first-ever experimental electron momentum density of Ag2CrO4 using 661.65 keV γ-rays from 20 Ci 137Cs source. To validate our experimental data, we have also deduced theoretical Compton profiles, energy bands and density of states using linear combination of atomic orbitals (LCAO) method in the framework of density functional theory. It is seen that the DFT-LDA gives a better agreement with experimental data than free atom model. The energy bands and density of states are also discussed. [ABSTRACT FROM AUTHOR]

Matrix absorption effects have been examined with scattered X-rays by using WDXRF system for Fe-Ca and Fe-Ti binary compounds. Fe as analyte and elements which some of them the K absorption edge just below the characteristic K X-ray energies of the analyte (Fe) as matrix have been chosen. Pure and binary with Fe ratio ranging from 10% to 90% samples were prepared with these elements. These samples have been analyzed in WDXRF system. At the end of measurement, the coherent and Compton scattering X-rays data of Rh Kα X-rays from these samples have been obtained. Matrix absorption effects have been examined by calculating coherent / Compton scattered X-rays intensity ratio. [ABSTRACT FROM AUTHOR]

We report on the status of extraction of Generalized Parton Distributions (GPDs) and Compton Form Factors (CFFs) from Deeply Virtual Compton Scattering (DVCS) data. [ABSTRACT FROM AUTHOR]

We study the production of doubly charged scalar and vector bileptons which are predicted several beyond the Standard Model scenarios, in polarized high energy eγ and γ γ collisions with the photon originating from Compton backscattering. We analyze the discovery potential and show how the use of polarized beams is to distinguish between scalar and vector bileptons in model-independent framework. [ABSTRACT FROM AUTHOR]

We present a novel NDT/NDE tool for non-contact, single-sided 3D inspection of aerospace components, based on Compton Imaging Tomography (CIT) technique, which is applicable to large, non-uniform, and/or multilayer structures made of composites or lightweight metals. CIT is based on the registration of Compton-scattered X-rays, and permits the reconstruction of the full 3D (tomographic) image of the inspected objects. Unlike conventional computerized tomography (CT), CIT requires only single-sided access to objects, and therefore can be applied to large structures without their disassembly. The developed tool provides accurate detection, identification, and precise 3D localizations and measurements of any possible internal and surface defects (corrosions, cracks, voids, delaminations, porosity, and inclusions), and also disbonds, core and skin defects, and intrusion of foreign fluids (e.g., fresh and salt water, oil) inside of honeycomb sandwich structures. The NDE capabilities of the system were successfully demonstrated on various aerospace structure samples provided by several major aerospace companies. Such a CIT-based tool can detect and localize individual internal defects with dimensions about 1-2 mm3, and honeycomb disbond defects less than 6 mm by 6 mm area with the variations in the thickness of the adhesive by 100 m. Current maximum scanning speed of aircraft/spacecraft structures is about 5-8 min/ft2 (50-80 min/m2). [ABSTRACT FROM AUTHOR]

Here we present new results of in situ nondestructive evaluation (NDE) of spacecraft thermal protection system materials obtained with POC-developed NDE tool based on a novel Compton Imaging Tomography (CIT) technique recently pioneered and patented by Physical Optics Corporation (POC). In general, CIT provides high-resolution threedimensional Compton scattered X-ray imaging of the internal structure of evaluated objects, using a set of acquired twodimensional Compton scattered X-ray images of consecutive cross sections of these objects. Unlike conventional computed tomography, CIT requires only one-sided access to objects, has no limitation on the dimensions and geometry of the objects, and can be applied to large multilayer non-uniform objects with complicated geometries. Also, CIT does not require any contact with the objects being imaged during its application. [ABSTRACT FROM AUTHOR]

In January/April 2015 Fermi-LAT detected strong gamma-ray flares from FSRQ PKS 1441+25 (z=0.939). During the flare in January the daily γ-ray flux reached up to (1.72±0.19)×10-6 photon cm-2 s-1 with the flux double time of ≈ 1.4 days. This flare is accompanied by similar flux increase, also in the X-ray band as observed by Swift XRT. The available X-ray and γ-ray data allows to constrain the underlying electron distribution parameters through Markov Chain Monte Carlo method. The emission in the low state can be interpreted by synchrotron self-Compton emission from the electron population producing the radio-to-X-ray emission in the jet while in the high state the emission is mostly produced from inverse-Compton up scattering of the external photons from dusty torus. [ABSTRACT FROM AUTHOR]

The results of the analysis of Fermi-LAT data from seven years of observations of the broad line radio galaxy 3C 120 are presented. Compared with the previous studies, now the new PASS 8 data allows to investigate the temporal variability in long and short time scales. The temporal analysis indicates significant variability in short time scales. The spectral analysis is performed for the energies above 100 MeV and high energy γ-rays are detected up to 10 GeV. The γ- ray spectrum can be described as synchrotron self-Compton emission from the electron population producing radio-to-Xray emission in the jet. The required electron energy density exceeds the one of magnetic field, only by a factor of 2.6 meaning no significant deviation from equipartition. [ABSTRACT FROM AUTHOR]

There are several types of Galactic sources that can potentially accelerate charged particles up to GeV and TeV energies. These accelerated particles can produce Very High Energy (VHE, E >100 GeV) γ-ray emission through different processes like for example inverse Compton scattering of ambient photon fields by accelerated electrons. We present here the results of our observations of the source class of γ-ray binaries and the subclass of binary systems known as novae with the MAGIC telescopes. The focus lies on the five sources: nova V339 Del, AE Aquarii, SS 433, MWC656 and LS I +61°303. The binary system LS I +61°303 was observed in a long-term monitoring campaign for 8 years. We show the newest results on our search for superorbital variability also in context with contemporaneous optical observations. MWC656 is a unique detected high-mass X-ray binary system, since it is up to now the only one known composed of a Be star and a black hole. Furthermore, we present the observations of the only super-critical accretion system known in our galaxy: SS 433. Finally, results of our multiwavelength observation campaign regarding the cataclysmic variable AE Aquarii and the results of the follow-up observations of the nova V339 Del will be discussed in these proceedings. [ABSTRACT FROM AUTHOR]

Recently theMAGIC collaboration reported about the extension of the pulsed gamma-ray emission from the Crab pulsar beyond 1 TeV. Despite the consensus between different theoretical models regarding the production mechanism of the pulsed VHE gamma-rays (the inverse Compton scattering of electrons), the origin of ultrarelativistic electrons and the location of the gamma-ray production region remain two key but highly uncertain issues. We discuss a possible scenario of production of the pulsed gamma-ray emission under the assumption that the acceleration of electrons takes place at the light cylinder and calculate the energy spectrum of high-energy radiation caused by the inverse Compton scattering in two target photon fields originating from the heated surface of the neutron star (thermal photons) and from the magnetosphere itself (nonthermal photons). The total rate of acceleration of relativistic electrons required to explain the observed flux of gamma-rays can be as small as 1 percent of the spin-down luminosity of the Crab pulsar. We argue that the magnetocentrifugal acceleration of plasma at the light cylinder is responsible for these electrons. [ABSTRACT FROM AUTHOR]

A unique Compton backscattering configuration for generating monochromatic, short pulse, and potentially coherent x-rays in a Laser Wakefield Accelerator (LWFA) is being studied at the Naval Research Laboratory. Reflection mechanisms such as stimulated Raman scattering and shock-created density gradients in a plasma can generate the required backward-travelling laser pulse directly from the same laser pulse used in the LWFA, i.e., the high energy electron beam and the counter-propagating photon beam are both self-generated by an ultrashort laser pulse in plasma. The automatic alignment of the counter-propagating electrons and photons together with the extended interaction distance and tightly guided beam sizes in a LWFA can lead to a high-gain situation for the Doppler upshifted forward propagating x-rays. Possibilities for exponential gain to achieve coherent generation of the x-rays are investigated. Using 1D warm beam FEL analysis, millimeter gain lengths could be obtained for optimistic energy spread and emittance parameters. [ABSTRACT FROM AUTHOR]

We demonstrate that electrons interacting with an optical, radially-polarized Bessel-beam emit radiation of identical characteristics as channeling radiation. However, because this happens in vacuum, there is no scattering caused by the crystal lattice as occurs in conventional channeling radiation. Contrary to inverse Compton radiation, the frequency is determined by the amplitude of the laser field rather than by its frequency. Other unique characteristics are presented. [ABSTRACT FROM AUTHOR]

Ongoing research on Compton radiation sources is aimed toward developing university-scale compact x-rayand gamma-radiation-sources. Novel conceptual approaches are being pursued along different routes: One research direction lies in multiplying the source's repetition rate, and increasing its average brightness by placing the point of Compton interaction inside an optical cavity. High-gradient plasma-wakefield accelerators are fast becoming a practical reality, offering a new paradigm for compact all-optical Compton sources operating in x-ray- and gamma-regions. Continually bettering the quality of the beam of plasma accelerators promises the achievement of fully coherent Compton x-rays, thereby prompting the evolution of the Compton source to an all-optical free-electron laser. Intense lasers can move the high-energy cut-off limit in a Compton spectrum by efficiently generating high-order harmonics. The ATF's user- and upgrade- programs based on ultra-fast CO2 laser technology strongly support all these research thrusts. [ABSTRACT FROM AUTHOR]

An ultrashort laser pulse incident on a sharp plasma gradient undergoes a partial reversal in Poynting flux. The resulting counterpropagating field can Compton backscatter from electrons accelerated in the incident pulse's wakefield. We examine the reversal mechanism and properties of the counterpropagating field to optimize the Compton scattered radiation. [ABSTRACT FROM AUTHOR]

Propagating a short, relativistically intense laser pulse in a plasma channel makes it possible to generate clean comb-like electron beams - sequences of synchronized, low phase-space volume bunches with controllable energy spacing [S. Y. Kalmykov et al., "Accordion Effect Revisited: Generation of Comb-Like Electron Beams in Plasma Channels," in Advanced Accelerator Concepts: 16th Workshop, AIP Conference Proceedings; this volume]. All-optical control of the electron beam phase space structure via manipulation of the drive pulse phase (negative chirp) and parameters of the channel enables the design of a tunable, all-optical source of polychromatic pulsed γ-rays using the mechanism of inverse Compton scattering. [ABSTRACT FROM AUTHOR]

Recently the UCLA BNL helical IFEL experiment at the Accelerator Test Facility (ATF) showed for the first time capture and high gradient acceleration of monoenergetic electron beams from a helical inverse free electron laser. Using a modest intensity ~1013 W/cm2 laser--several orders of magnitude less than those used in laser wake-field accelerators--and a strongly tapered 0.5 m long helical undulator, we demonstrated energy doubling of a 52 MeV electron beam with >100 MV/m average accelerating gradient and excellent output beam quality. In order to improve the fraction of electrons captured, a prebuncher module is being prepared for testing next month. Simulations show that 70 to 90% of the beam should be accelerated to a final energy of 97 MeV with 2% energy spread. The high efficiency acceleration will enable the first IFEL driven inverse Compton scattering experiment. [ABSTRACT FROM AUTHOR]

This paper summarizes the presentations and discussions of Working Group 5: Beam and radiation generation, monitoring and control. This working group was part of the 2014 Advanced Accelerator Concepts Workshop held in San Jose, CA. There was a very broad range of topics and discussions covered by this working group, which we cover as follows: light sources and diagnostics, Compton scattering sources, Betatron radiation, and electron sources, diagnostics, accelerators. [ABSTRACT FROM AUTHOR]

Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source (APS). The next generation XBPMs for high heat load front ends (HHL FEs) have been designed to meet these requirements by utilizing Cu K-edge x-ray fluorescence (XRF) from a pair of copper absorbers and have been installed at the front ends (FEs) of the APS. Commissioning data showed a significant performance improvement over the existing photoemission-based XBPMs. While a similar design concept can be applied for the canted undulator front ends, where two undulator beams are separated by 1.0-mrad, the lower beam power (< 10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from the diamond blades placed edge-on to the xray beam. A prototype of the Compton scattering XBPM system was installed at 24-ID-A in May 2015. In this report, the design and test results for XRF-based XBPM and Compton scattering based XBPM are presented. Ongoing research related to the development of the next generation XBPMs on thermal contact resistance of a joint between two solid bodies is also discussed. [ABSTRACT FROM AUTHOR]

We review theoretical progress and prospects for determining the nucleon's static dipole polarisabilities from Compton scattering on few-nucleon targets, including new values; see Refs. [1-5] for details and a more thorough bibliography. [ABSTRACT FROM AUTHOR]

Novel nondestructive evaluation (NDE) systems based on a recently pioneered Compton Imaging Tomography (CIT) technique are currently being developed by Physical Optics Corporation (POC). CIT provides high-resolution three-dimensional Compton scattered X-ray imaging of the internal structure of evaluated objects, using a set of acquired two-dimensional Compton scattered X-ray images of consecutive cross sections of these objects. Unlike conventional computed tomography, CIT requires only one-sided access to objects, has no limitation on the dimensions and geometry of the objects, and can be applied to large multilayer nonuniform objects with complicated geometries. Also, CIT does not require any contact with the objects being imaged during its application. [ABSTRACT FROM AUTHOR]

The Compton scattering is able to determine the signature of land mine detection based on dependency of density anomaly and energy change of scattered photons. In this study, 4.43 MeV gamma of the Am-Be source was used to perform Compton scattering. Two detectors were placed between source with distance of 8 cm and radius of 1.9 cm. Detectors of thallium-doped sodium iodide NaI(TI) was used for detecting gamma ray. There are 9 anomalies used in this simulation. The physical of anomaly is in cylinder form with radius of 10 cm and 8.9 cm height. The anomaly is buried 5 cm deep in the bed soil measured 80 cm radius and 53.5 cm height. Monte Carlo methods indicated the scattering of photons is directly proportional to density of anomalies. The difference between detector response with anomaly and without anomaly namely contrast ratio values are in a linear relationship with density of anomalies. Anomalies of air, wood and water give positive contrast ratio values whereas explosive, sand, concrete, graphite, limestone and polyethylene give negative contrast ratio values. Overall, the contrast ratio values are greater than 2% for all anomalies. The strong contrast ratios result a good detection capability and distinction between anomalies. [ABSTRACT FROM AUTHOR]

The coherent (Rayleigh) to incoherent (Compton) scattering cross-section ratio of elements, in the range 13 = Z = 82, are determined experimentally for 59.54 keV incident gamma photons. An HPGe (High purity germanium) semiconductor detector is employed, at scattering angle of 110°, to record the spectra originating from interactions of incident gamma photons with the target under investigation. The intensity ratio of Rayleigh to Compton scattered peaks observed in the recorded spectra, and corrected for photo-peak efficiency of gamma detector and absorption of photons in the target and air, along with the other required parameters provides the differential cross-section ratio. The measured values of cross-section ratio are found to agree with theoretical predictions based upon non-relativistic form factor, relativistic form factor, modified form factor and S-matrix theory. [ABSTRACT FROM AUTHOR]

A Compton scattering technique is presented to determine density and void location in the given wooden samples. The technique uses a well collimated gamma ray beam from 137Cs along with the NaI(Tl) scintillation detector. First, a linear relationship is established between Compton scattered intensity and known density of chemical compounds, and then density of the wood is determined from this linear relation. In another experiment, the ability of penetration of gamma rays is explored to detect voids in wooden (low Z) sample. The sudden reduction in the Compton scattered intensities agrees well with the position and size of voids in the wooden sample. It is concluded that wood density and the voids of size ~ 4 mm and more can be detected easily by this method. [ABSTRACT FROM AUTHOR]

Ultraperipheral collisions in hadron colliders give new opportunities to investigate the hadron structure through exclusive photoproduction processes. We describe the possibility of measuring the Generalized Parton Distributions in the Timelike Compton Scattering process and in the production of heavy vector meson. [ABSTRACT FROM AUTHOR]

brief experimentalist's introduction to Generalized Parton Distributions (GPDs) is given. Recent COMPASS results are shown on transverse target-spin asymmetries in hard exclusive ρn and their interpretation in terms of a phenomenological model as indication for chiral-odd, transverse GPDs is discussed. For deeply virtual Compton scattering, it is briefly outlined how to access GPDs and projections are shown for future COMPASS measurements. [ABSTRACT FROM AUTHOR]

Using Geant4, a complex simulation code of the interaction between laser photons and relativistic electrons was developed. We implemented physically constrained electron beam emittance and spacial distribution parameters and we also considered a Gaussian laser beam. The code was tested against experimental data produced at the ?-ray beam line GACKO (Gamma Collaboration Hutch of Konan University) of the synchrotron radiation facility NewSUBARU. Here we will discuss the implications of transverse missallignments of the collimation system relative to the electron beam axis. [ABSTRACT FROM AUTHOR]

Photoneutron cross sections for seven samarium isotopes, 144Sm, 147Sm, 148Sm, 149Sm, 150Sm, 152Sm and 154Sm, have been investigated near neutron emission threshold using quasimonochromatic laser-Compton scattering γ-rays produced at the synchrotron radiation facility New SUBARU. The results are important for nuclear astrophysics calculations and also for probing γ-ray strength functions in the vicinity of neutron threshold. Here we describe the neutron detection system and we discuss the related data analysis and the necessary method improvements for adapting the current experimental method to the working parameters of the future Gamma Beam System of Extreme Light Infrastructure - Nuclear Physics facility. [ABSTRACT FROM AUTHOR]

The Gamma Beam System of ELI-NP will produce brilliant, quasi-monochromatic gamma-ray beams via Inverse Compton Scattering of short laser pulses on relativistic electron beam pulses. The scattered radiation is Doppler upshifted by more than 1,000,000 times and is forward focused in a narrow, polarized, tunable, laser-like beam. The gamma-ray beam at ELI-NP will be characterized by large spectral density of about 104 photons/s/eV, narrow bandwidth (< 0.5%) and tunable energy from 200 keV up to about 20 MeV. The Gamma Beam System is a state-of-the-art equipment employing techniques and technologies at the limits of the present-day's knowledge. [ABSTRACT FROM AUTHOR]

Collinear and kT - factorizations were introduced from different theoretical considerations and for different perturbative methods. We demonstrate that they both can be obtained from a more general factorization. We prove that they can be related to each other with imposing a simple assumption for the unintegrated parton distributions [ABSTRACT FROM AUTHOR]

Topaz occurs in a wide range of colors, including yellow, orange, brown, pink-to-violet and blue. All of these color differences are due to color centers. In order to improve the color of natural colorless topaz, the most commonly used is irradiated with x- or gamma-rays, indicated that attenuation parameters is important to enhancements by irradiation. In this work, the mass attenuation coefficients of blue topaz were measured at the different energy of γ-rays using the Compton scattering technique. The results show that, the experimental values of mass attenuation coefficient are in good agreement with the theoretical values. The mass attenuation coefficients increase with the decrease in gamma rays energies. This may be attributed to the higher photon interaction probability of blue topaz at lower energy. This result is a first report of mass attenuation coefficient of blue topaz at different gamma rays energies. [ABSTRACT FROM AUTHOR]

Theory and prospects of Compton scattering on nucleons and light nuclei below 500MeV are outlined; cf. [1-3]. [ABSTRACT FROM AUTHOR]

Material screening for identifying low-energy electron emitters and alpha-decaying isotopes is now a prerequisite for rare-event searches (e.g., dark-matter direct detection and neutrinoless double-beta decay) for which surface radiocon-tamination has become an increasingly important background. The BetaCage, a gaseous neon time-projection chamber, is a proposed ultra-sensitive (and nondestructive) screener for alpha-and beta-emitting surface contaminants to which existing screening facilities are insufficiently sensitive. Sensitivity goals are 0.1 betas keV-1 m-2 day-1 and 0.1 alphas m-2 day-1, with the former limited by Compton scattering of photons in the screening samples and (thanks to tracking) the latter expected to be signal-limited; radioassays and simulations indicate backgrounds from detector materials and radon daughters should be subdominant. We report on details of the background simulations and detector design that provide the discrimination, shielding, and radiopurity necessary to reach our sensitivity goals for a chamber with a 95 × 95 cm2 sample area positioned below a 40 cm drift region and monitored by crisscrossed anode and cathode planes consisting of 151 wires each. [ABSTRACT FROM AUTHOR]

The location of objects hidden in dense matter and the analysis of metallic surfaces using gamma backscattering are two possible applications strongly suggested here with experiments, highlevel Monte Carlo simulations, and some supporting basic theory. [ABSTRACT FROM AUTHOR]

The feasibility for a precise determination of Generalized Parton Distribution (GPDs) functions at an Electron Ion Collider (EIC) has been explored. The high luminosity of the machine, together with the large resolution and rapidity acceptance of the new dedicated detector, will open opportunity for high precision measurements of GPDs. We report on the study of GPDs from deeply virtual Compton scattering (DVCS). We also point out that such measurements at a proposed EIC provide insight to both, the transverse distribution of sea quarks and gluons as well as the proton spin decomposition. [ABSTRACT FROM AUTHOR]

We use gauge/gravity duality to study deeply virtual Compton scattering (DVCS) in the limit of high center of mass energy at fixed momentum transfer, corresponding to the limit of low Bjorken x, where the process is dominated by the exchange of the pomeron. At strong coupling, the pomeron is described as the graviton Regge trajectory in AdS space, with a hard wall to mimic confinement effects. This model agrees with HERA data in a large kinematical range. The behavior of the DVCS cross section for very high energies, inside saturation, can be explained by a simple AdS black disk model. In a restricted kinematical window, this model agrees with HERA data as well. [ABSTRACT FROM AUTHOR]

The HERMES collaboration presents two sets of recent results: the first related to an extraction of the g2 nucleon structure function determined for DIS on a polarised target and the second related to the measurement of asymmetries related to the deeply virtual Compton scattering process that can be used to discover information on generalised parton distributions and hence nucleon structure. [ABSTRACT FROM AUTHOR]

Quantum theory claims that electron is pointlike and structureless. Contrary, the consistent with Gravity electron is considered as a gravitating soliton based on the Kerr-Newman (KN) solution. The KN electron model indicates its extended structure of the Compton size rc = ħ/m and sheds a new light on some old puzzles of quantum theory. In particular, the KN Gravity predicts the topologically nontrivial background of the electron, formed by a closed string of the heterotic type. We argue that this string can be detected by the novel experimental tool - nonforward Compton Scattering. If it will be confirmed, it would be of primary importance for foundations of Quantum theory and unification of Quantum theory with Gravity. [ABSTRACT FROM AUTHOR]

Cosmic ray acceleration and magnetic amplification in supernova remnants is shortly reviewed. The results on the modeling of broadband electromagnetic emission from supernova remnants are presented. [ABSTRACT FROM AUTHOR]

A new Radon transform defined on a discontinuous curve formed by a pair of half-lines forming a letter V is defined and studied. We establish its analytic inverse formula, its related filtered back-projection reconstruction procedure and its numerical analysis. These theoretical results allow the reconstruction of two-dimensional images of a radiating object from its Compton scattered rays measured on a one-dimensional collimated camera. Numerical simulations results illustrate the performance of the new imaging process. [ABSTRACT FROM AUTHOR]

We present an overview of the two SPring-8 diagnostics beamlines, the beamline I (dipole magnet source) and II (insertion device source). At the beamline I, synchrotron radiation (SR) in both the X-ray and the visible bands is exploited for characterizations of the electron beam. At the beamline II, by observing the spectral, spatial, and temporal characteristics of X-ray SR of the insertion device (ID), new techniques for accelerator diagnostics are investigated. Irradiation experiments with the ID to develop accelerator components such as photon absorbers, and production of intensive 10 MeV γ-rays by backward Compton scattering of external far infrared (FIR) laser photons are being prepared at the beamline II. [ABSTRACT FROM AUTHOR]