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1

Compton scattering gamma-ray source optimization  

NASA Astrophysics Data System (ADS)

The interaction of a bright relativistic electron beam with an intense laser pulse via Compton scattering can generate tunable gamma-rays for precision nuclear photonics applications. The properties of the gamma-ray phase space will be outlined, in relation with the 6D electron bunch and 6D laser pulse phase space, along with collimation, nonlinear effects and other sources of spectral broadening. Optimization strategies will be outlines within the context of nuclear photonics applications.

Hartemann, Frederic; Wu, Sheldon; Albert, Félicie; Barty, Chris

2012-10-01

2

Experiment on iodine transmutation by laser Compton scattering gamma ray  

NASA Astrophysics Data System (ADS)

A laser Compton scattering gamma-ray based nuclear transmutation is proposed to reduce the hazards of long-lived activity nuclear waste. In accordance with this proposal, a laser Compton scattering gamma-ray facility has been built on NewSUABARU storage ring. The facility provides 17.6 MeV gamma-ray photons, which is applicable to the nuclear transmutation research. In order to investigate the reaction rate of Iodine material, the 23Na127I target is adopted for the irradiation experiment. The results show that the experimental data is close to the simulation result.

Li, D.; Imasaki, K.; Miyamoto, S.; Horikawa, K.; Amano, S.; Mochizuki, T.

2008-05-01

3

Gamma-Deuteron Compton Scattering in Effective Field Theory  

SciTech Connect

The differential cross section for {gamma}-deuteron Compton scattering is computed to next-to-leading order (NLO) in an effective field theory that describes nucleon-nucleon interactions below the pion production threshold. Contributions at NLO include the nucleon isoscalar electric polarizability from its 1/m{sub {pi}} behavior in the chiral limit. The parameter free prediction of the {gamma}-deuteron differential cross section at NLO is in good agreement with data.

Jiunn-Wei Chen; Harald W. Griesshammer; Martin J. Savage; Roxanne P. Springer

1998-12-01

4

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Technical Reports Server (NTRS)

The Thomson limit of resonant inverse Compton scattering in the strong magnetic fields of neutron stars is considered as a mechanism for producing gamma-ray burst continuum spectra. Photon production spectra and electron cooling rates are presented using the full magnetic Thomson cross-section. Model emission spectra are obtained as self-consistent solutions of a set of photon and electron kinetic equations, displaying spectral breaks and other structure at gamma-ray energies.

Baring, M. G.

1995-01-01

5

Design Study for Direction Variable Compton Scattering Gamma Ray  

NASA Astrophysics Data System (ADS)

A monochromatic gamma ray beam is attractive for isotope-specific material/medical imaging or non-destructive inspection. A laser Compton scattering (LCS) gamma ray source which is based on the backward Compton scattering of laser light on high-energy electrons can generate energy variable quasi-monochromatic gamma ray. Due to the principle of the LCS gamma ray, the direction of the gamma beam is limited to the direction of the high-energy electrons. Then the target object is placed on the beam axis, and is usually moved if spatial scanning is required. In this work, we proposed an electron beam transport system consisting of four bending magnets which can stick the collision point and control the electron beam direction, and a laser system consisting of a spheroidal mirror and a parabolic mirror which can also stick the collision point. Then the collision point can be placed on one focus of the spheroid. Thus gamma ray direction and collision angle between the electron beam and the laser beam can be easily controlled. As the results, travelling direction of the LCS gamma ray can be controlled under the limitation of the beam transport system, energy of the gamma ray can be controlled by controlling incident angle of the colliding beams, and energy spread can be controlled by changing the divergence of the laser beam.

Kii, T.; Omer, M.; Negm, H.; Choi, Y. W.; Kinjo, R.; Yoshida, K.; Konstantin, T.; Kimura, N.; Ishida, K.; Imon, H.; Shibata, M.; Shimahashi, K.; Komai, T.; Okumura, K.; Zen, H.; Masuda, K.; Hori, T.; Ohgaki, H.

2013-03-01

6

Bursts of gamma rays from Compton scattering at cosmological distances  

NASA Technical Reports Server (NTRS)

Compton scattering of the microwave background photons by beams of ultrarelativistic electrons at large redshifts, z much greater than 1, is proposed as a source of some gamma-ray bursts. Such beams may be produced by cusps on superconducting cosmic strings. In the present model, a very narrow beam of ultrarelativistic electron-positron pairs scatters the microwave background photons into a very narrow beam of gamma rays. While the pairs lose energy, the beam of gamma rays opens up and sweeps the observer. The expected time variability and spectra of the resulting gamma-ray burst are calculated. The bursts have a rapid rise time, followed by a more gradual decline. The spectra are initially very hard and become softer during the decline.

Zdziarski, Andrzej A.; Svensson, Roland; Paczynski, Bohdan

1991-01-01

7

Commissioning of a Compton-Scattering-Based Gamma Ray Source  

NASA Astrophysics Data System (ADS)

Recently a Compton-scattering based gamma-ray source, in which a high-intensity laser scatters off a high-brightness electron beam and emerges as a narrow-band gamma-ray beam, has been commissioned at Lawrence Livermore National Laboratory. Operating at energies from 0.1 to 0.9 MeV, the source produces fluxes upwards of 10^6 photons/sec with a brightness of 10^ 15 photons/s/mm^2/mrad^2/0.1% BW. Presented here is a discussion of the design and performance of the laser and electron subsystems that are used to drive the source, and an overview of the parameters of the generated gamma-ray beam.

Gibson, David; Albert, Felicie; Anderson, Scott; Hartemann, Fred; Messerly, Mike; Shverdin, Miro; McNabb, Dennis; Siders, Craig; Barty, Chris

2009-11-01

8

Quantum Beam Generation by Laser Compton Scattering Gamma-Ray  

NASA Astrophysics Data System (ADS)

Energy and flux of positrons and neutrons generated in the electron storage ring NewSUBARU by laser Compton scattering with Nd (1.064 ?m,) laser beams were measured. The energy of positrons was measured with an imaging plate. The positron energy has a peak around 10 MeV. With a 3 mm thick Pb target, about 3600 positron sec-1 can be generated and the maximum generation rate of 0.0436 positron photon-1 can be obtained under the top-up mode operation. The generation rate is defined to be the number of positrons generated per the incident single gamma-ray photon. The energy of neutrons was measured with a time of flight. The maximum neutrons energy is around 8 MeV which agreed well with the obtained result 8.6 MeV.

Horikawa, Ken; Miyamoto, Shuji; Amano, Sho; Li, Dazhi; Imasaki, Kazuo; Mochizuki, Takayasu

9

Photo-nuclear Science using laser Compton scattering gamma-rays in JAEA  

NASA Astrophysics Data System (ADS)

The laser Compton scattering gamma-rays are a new generation of gamma-rays which have advantages of tunable energy, high energy resolution, and almost 100% polarization. These gamma-rays have been used for wide fields as nuclear physics, nuclear astrophysics, and atomic energy engineering. One of the most important topics is a management of nuclear waste. We have proposed a novel non-destructive assay method for isotopes using nuclear resonance fluorescence measurement with the Compton scattering gamma-rays. This assay system is useful for the nuclear waste management. We have successfully demonstrated the detection of a target isotope hidden in heavy metals. We used these gamma-rays for the study of the nuclear physics and nuclear astrophysics. We also have developed a new Compton scattering gamma-ray source with an energy region of sub-MeV.

Hayakawa, Takehito; Hajima, Ryoichi

2008-06-01

10

High-Power Laser Pulse Recirculation for Inverse Compton Scattering-Produced Gamma-Rays  

SciTech Connect

Inverse Compton scattering of high-power laser pulses on relativistic electron bunches represents an attractive method for high-brightness, quasi-monoenergetic {gamma}-ray production. The efficiency of {gamma}-ray generation via inverse Compton scattering is severely constrained by the small Thomson scattering cross section. Furthermore, repetition rates of high-energy short-pulse lasers are poorly matched with those available from electron accelerators, resulting in low repetition rates for generated {gamma}-rays. Laser recirculation has been proposed as a method to address those limitations, but has been limited to only small pulse energies and peak powers. Here we propose and experimentally demonstrate an alternative method for laser pulse recirculation that is uniquely capable of recirculating short pulses with energies exceeding 1 J. Inverse Compton scattering of recirculated Joule-level laser pulses has a potential to produce unprecedented peak and average {gamma}-ray brightness in the next generation of sources.

Jovanovic, I; Shverdin, M; Gibson, D; Brown, C

2007-04-17

11

The limitations of resonant Compton scattering as a gamma-ray burst model  

NASA Technical Reports Server (NTRS)

Resonant Compton upscattering is commended as a mechanism that produces a hard gamma-ray spectrum while suppressing X-rays. This model, however, has severe physical and observational limitations. Effective X-ray suppression places a lower limit on the electron density; above this limit X-rays scatter multiple times, so the single-scattering approximation of this mechanism is invalid. Multiple scattering produces a spectrum that is much harder than the single-scattering spectrum. As the Thomson optical depth of a power-law electron beam approaches unity, photon spawning commences at a high rate and physically invalidates the underlying electron distribution. The Compton upscattering model is therefore only valid over a narrow range of electron densities. An observational consequence of this model is the absence of the third cyclotron resonance. Resonant scattering produces gamma-rays that propagate nearly along the magnetic field. The resonant cross section of the third harmonic, which is strongly angle dependent, falls below the Compton continuum for these gamma rays. The observation of a third cyclotron resonance in a gamma-ray burst spectrum would eliminate resonant Compton scattering as a gamma-ray burst process.

Brainerd, J. J.

1992-01-01

12

Quality Control of Pavements and Tarmacs Using ({sup 137}Cs){gamma} Compton Scattering  

SciTech Connect

The {gamma} Compton scattering over a volume of concrete has been studied in order to design an instrument for density measurements. It will be used for the quality control in road construction, where large surfaces must be monitored. The experimental results and Monte Carlo simulations of the {gamma} Compton scattering over homogeneous and inhomogeneous volumes of concrete are shown. MC simulations have been useful to optimize the values of several parameters to improve the experimental set up and to estimate the extension of the explored volume.

Pino, F.; Barros, H.; Bernal, M.; Sajo-Bohus, L.; Palacios, D.; Greaves, E. D.; Viesti, G. [Nuclear Physics Laboratory, Simon Bolivar University, Caracas (Venezuela, Bolivarian Republic of)

2010-08-04

13

Positron generation through laser Compton scattering gamma ray  

NASA Astrophysics Data System (ADS)

The positron source is developed through a high brightness gamma-ray beam, which is produced from a laser light scattering off a high-energy electron beam circulating in a storage ring. A thin Pb target is irradiated by the gamma ray to generate positrons via pair creation. By using imaging plate, we measured the generation rate and worked out the energy spectrum of generated positrons and electrons. The experimental results are close to that from Monte Carlo simulation. About 3618 positrons/s at several MeV can be generated by the present experimental setup, and this value can be improved by optimizing experimental conditions.

Li, D.; Imasaki, K.; Miyamoto, S.; Horikawa, K.; Amano, S.; Mochizuki, T.

2009-03-01

14

Performance of the Laser Compton Scattering Gamma-Ray Source at SAGA-LS  

NASA Astrophysics Data System (ADS)

A laser Compton scattering gamma-ray source was constructed at the SAGA light source facility. To produce high-flux gamma rays in the few MeV region, we used a CO2 laser with a 10.6 ?m wavelength. Head-on collisions between the laser photons and the 1.4 GeV electron beam in the storage ring can produce gamma rays up to a maximum energy of 3.5 MeV without affecting the light source performance. The performance of the LCS source with respect to the stability of gamma-ray flux during continuous operation is reported.

Kaneyasu, T.; Takabayashi, Y.; Iwasaki, Y.; Koda, S.

2013-03-01

15

Design and Initial Operation of a Tunable Compton-Scattering Based Gamma-Ray Source  

NASA Astrophysics Data System (ADS)

Tunable, monochromatic gamma-ray sources are currently being developed at LLNL for nuclear photo-science and related applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector and offer a path to high-brightness high-energy (> 1 MeV) x-ray & gamma-rays due to their favorable scaling with electron energy. The current demonstration source, called the ``Thomson-Radiated Extreme X-Ray" (T-REX) source, targets photon energies up to 1 MeV. With extensive modeling using PARMELA and well-benchmarked custom Compton-scattering simulation codes, the optimal design parameters for an interaction (including factors such as the collision angle, focal spot size, bunch charge, laser intensity, pulse duration, and laser beam path) can be determined. Here we present the results of this optimization, including early experimental results from the newly commissioned system.

Gibson, David; Anderson, Scott; Betts, Shawn; Johnson, Micah; McNabb, Dennis; Messerly, Mike; Pruet, Jason; Shverdin, Miroslav; Tremaine, Aaron; Hartemann, Fred; Siders, Craig; Barty, Chris

2007-11-01

16

MeV Mono-Energetic Gamma Ray Compton Scattering Source R&D  

NASA Astrophysics Data System (ADS)

A precision, tunable gamma-ray source driven by a compact, high-gradient X-band linac is currently under development at LLNL. High-brightness, relativistic electron bunches produced by the linac interact with a Joule-class, 10 ps laser pulse to generate tunable ?-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. The source will be used to excite nuclear resonance fluorescence lines in various isotopes; applications include homeland security, stockpile science and surveillance, nuclear fuel assay, and waste imaging and assay. The source design, key parameters, and current status are presented.

Hartemann, Fred; Albert, Felicie; Anderson, Scott; Chu, Sam; Cross, Rick; Ebbers, Chris; Gibson, David; Messerly, Mike; Semenov, Vlad; Shverdin, Miro; Siders, Craig; McNabb, Dennis; Barty, Chris; Vlieks, Arnold; Tantawi, Sami

2009-11-01

17

Nondestructive detection of hidden chemical compounds with laser Compton-scattering gamma rays.  

PubMed

A nondestructive assay method for measuring a shielded chemical compound has been proposed. The chemical compound is measured by using a nuclear resonance fluorescence (NRF) measurement technique with an energy tunable laser Compton-scattering (LCS) gamma-ray source. This method has an advantage that hidden materials can be detected through heavy shields such as iron plates of a thickness of several centimeters. A detection of a chemical compound of melamine, C(3)H(6)N(6), shielded by 15-mm-thick iron and 4-mm-thick lead plates is demonstrated. The NRF gamma-rays of (12)C and (14)N of the melamine are measured by using the LCS gamma-rays of the energies of up to 5.0 MeV. The observed ratio ((12)C/(14)N)(exp)=0.39+/-0.12 is consistent with (C/N)(melamine)=0.5. PMID:19405694

Hayakawa, Takehito; Ohgaki, Hideaki; Shizuma, Toshiyuki; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Minehara, Eisuke; Kii, Toshiteru; Toyokawa, Hiroyuki

2009-04-01

18

Experiments with compton back scattered gamma beams (on GRAAL collaboration results)  

NASA Astrophysics Data System (ADS)

Experimental study of photonuclear reactions using Compton back scattered gamma beams at intermediate energies (from pion photoproduction threshold up to a few GeV) is reviewed. The last review of this subject was published about 10 years ago. Since then, new fundamental data on nucleon spin structure and photonuclear excitation mechanisms have appeared in the literature. Principal attention in the present review is paid to the GRAAL (Grenoble Accelerateur Anneau Laser) experiment conducted at ESRF (European Synchrotron Radiation Facility). It is shown that, in addition to the principal polarization experimental program based on high degree of gamma beam polarization, new results on different applications have been obtained. For example, total photoabsorption and partial meson photoproduction cross sections were measured with high accuracy, and a new method for studying an interaction of unstable short-lived mesons with nuclear media (tagged mesons) was proposed. New results on anisotropy of the speed of light with respect to the dipole of cosmic microwave background radiation were evaluated. It is noted that new opportunities arise due to unique conditions appearing while conducting the experiments with the Compton back scattering technique, which provides the hard photon spectrum, high degree of beam polarization, and low backgrounds.

Nedorezov, V. G.

2012-05-01

19

Pulse width measurement of laser Compton scattered gamma rays in picosecond range  

NASA Astrophysics Data System (ADS)

Ultra-short gamma ray pulses of the picosecond and femtosecond ranges can be generated using laser Compton scattering with 90° collisions at the UVSOR-II electron storage ring. Measurement techniques for a gamma ray pulse width in the femtosecond range are being developed. As the first stage of pulse width measurement, we tested a pulse width measuring method for the gamma rays with pulse width of 4.8 ps (FWHM) consisted of a multi-pixel photon counter (MPPC) and a digital oscilloscope. The time resolution of the MPPC was measured as 477 ps (FWHM) by using a single photon counting technique. The results indicated that the shortest pulse width that an MPPC can evaluate is 82 ps under ideal conditions. However, the experimental data were affected by a time jitter. The measured gamma ray pulse width including time jitter was 540 ps. The main reason for the large discrepancy was considered to be the noise of the trigger signal. We successfully reduced the time jitter to 77 ps after an improvement. As the next stage, we will develop a pulse width measurement technique in the femtosecond range by using a pump-probe technique with a femtosecond laser and ultra-short gamma ray pulses.

Taira, Y.; Adachi, M.; Zen, H.; Yamamoto, N.; Hosaka, M.; Soda, K.; Katoh, M.

2012-12-01

20

Feasibility study of ultra-short gamma ray pulse generation by laser Compton scattering in an electron storage ring  

NASA Astrophysics Data System (ADS)

We are developing an ultra-short gamma ray pulse source based on laser Compton scattering technology. Ultra-short gamma ray pulses can be generated by injecting femtosecond laser pulses into the electron beam circulating in an electron storage ring from the direction perpendicular to the orbital plane. The energy, intensity, and pulse width of the gamma rays are estimated to be 6.6 MeV, 2.4×106 photons s-1, and 288 fs, respectively, for the case of a 750 MeV electron storage ring with a commercially available femtosecond laser. A preliminary head-on collision experiment was conducted. The measured spectral shape agreed well with the simulation, including the detector response calculated by the EGS5 code. The results implied that the generation of gamma rays occurred by laser Compton scattering and confirmed the validity of the estimation of the gamma ray intensity in the case of 90° collisions.

Taira, Y.; Adachi, M.; Zen, H.; Tanikawa, T.; Hosaka, M.; Takashima, Y.; Yamamoto, N.; Soda, K.; Katoh, M.

2011-05-01

21

Application of Laser Compton Scattered gamma-ray beams to nondestructive detection and assay of nuclear material  

NASA Astrophysics Data System (ADS)

Generation of energy-tunable gamma-rays via Laser Compton Scattering is of great interest for scientific studies and applications of "MeV" photons which interact with nuclei. One of the promising applications of such energy-tunable gamma-rays is the nondestructive detection and assay of nuclides which are necessary for nuclear security and safeguards. We are developing technologies relevant to gamma-ray nondestructive detection and assay, which include a high-brightness gamma-ray source based on modern laser and accelerator technologies, and gamma-ray measurement methods optimized for highly radioactive samples.

Hajima, R.; Hayakawa, T.; Shizuma, T.; Angell, C. T.; Nagai, R.; Nishimori, N.; Sawamura, M.; Matsuba, S.; Kosuge, A.; Mori, M.; Seya, M.

2014-05-01

22

Compton scattering and the gamma-ray power-law spectrum in Markarian 421  

NASA Technical Reports Server (NTRS)

The nearest BL Lac object, Mrk 421, has a gamma-ray spectrum which is approximately flat in EF-sub E from E less than about 50 MeV to E greater than about 1 TeV. Inverse Compton scattering can explain this smooth spectrum, despite the structure in the Klein-Nishina cross section, if the injected electron distribution function is proportional to gamma exp -2, where gamma is the electron Lorentz factor. When this is the case, the structure imprinted on the steady state electron distribution function by the structure in the Klein-Nishina cross section is almost exactly compensated in the radiated spectrum. Because particle acceleration in strong shocks injects particles with this distribution function, this shape injection function is in fact quite plausible. Other blazars may be explained by the same model if the cutoff below TeV energies observed in other objects is due to pair production on the cosmological IR background, as suggested by Stecker et al. (1992).

Zdziarski, Andrzej A.; Krolik, Julian H.

1993-01-01

23

Compton scattering overview  

SciTech Connect

An overview of linear and nonlinear Compton scattering is presented, along with a comparison with Thomson scattering. Two distinct processes play important roles in the nonlinear regime: multi-photon interactions, leading to the generation of harmonics, and radiation pressure, yielding a downshift of the radiated spectral features. These mechanisms, their influence on the source brightness, and different modeling strategies are also briefly discussed.

Hartemann, F V

2008-12-01

24

Properties and applications of mono-energetic gamma-rays from laser-Compton scattering  

NASA Astrophysics Data System (ADS)

Properties of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. It produces 0.1 MeV-0.9 MeV photons. Its experimental key parameters are: its size (0.01 mm^2), divergence (10x6 mrad^2), duration (ps), spectrum (15% bandwidth) and intensity (10^5 photons/shot), which yield an on-axis peak brightness of ˜10^15 photons/mm^2/mrad^2/s/0.1% bandwidth at 0.478 MeV. We detected the 0.478 MeV nuclear resonance fluorescence (NRF) line of ^7Li. A LiH sample was in the beam path, and the NRF scattered photons were detected by a germanium detector oriented at 90^o with respect to the incident beam axis. The resulting spectrum shows the 0.478 MeV line of ^7Li, with several characteristic lines from the interaction. With this experiment, we have shown that MEGa-Ray sources will provide a unique specific isotope detection capability. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Albert, Felicie; Anderson, Scott; Anderson, Gerry; Betts, Shawn; Gibson, David; Hagmann, Christian; Johnson, Micah; Messerly, Mike; Shverdin, Miroslav; Hartemann, Frederic; Siders, Craig; McNabb, Dennis; Barty, Christopher

2009-11-01

25

Nucleon Compton Scattering.  

National Technical Information Service (NTIS)

Review of Nucleon Compton Scattering in wide angle regime is presented. JLab experimental data strongly support dominance of handbag mechanism in the RCS process. The approved ALLRCS experiment with polarized target and future plans with 12 GeV beam are d...

B. Wojtsekhowski

2006-01-01

26

Compton scattering with low intensity radioactive sources  

NASA Astrophysics Data System (ADS)

Compton scattering experiments with gamma rays typically require a ``hot'' source (˜5mCi of Cs137) to observe the scattering as a function of angle. (See Ortec AN34 Experiment #10 Compton Scattering) Here a way is described to investigate Compton scattering with micro Curie level radioactive sources that are more commonly available in the undergraduate laboratory. A vertical-looking 2 inch coaxial hpGe detector, collimated with a 2 inch thick lead shield, was used. Cylindrical Al targets of various thicknesses were placed over the collimator and several available sources were placed around the target so that the average Compton scattering angle into the collimator was 90 deg. A peak could be observed at the expected energy for 90 deg. Compton scattering by doing 24 hour target-in minus target-out runs. The peak was broadened by the spread in the scattering angle due to the variation in the angle of the incoming gamma ray and the angular acceptance of the collimator. A rough analysis can be done by modeling the angular spread due to the geometry and correcting for the gamma ray absorption from the target center. Various target materials and sources can be used and some variation in average Compton scattering angle can be obtained by adjusting the geometry of the source and target.

Quarles, Carroll

2012-03-01

27

Compton Gamma Ray Observatory Guest Investigator Program  

NASA Technical Reports Server (NTRS)

This paper presents a final report for the Compton Gamma Ray Observatory Guest Investigator Program from 06/01/91-07/31/97. The topics include: 1) Solar Flare Neutron Spectra and Accelerated Ions; 2) Gamma Ray Lines From The Orion Complex; 3) Implications of Nuclear Line Emission From The Orion Complex; 4) Possible Sites of Nuclear Line Emission From Massive OB Associations; 5) Gamma-Ray Burst Repitition and BATSE Position Uncertainties; 6) Effects of Compton Scattering on BATSE Gamma-Ray Burst Spectra; and 7) Selection Biases on the Spectral and Temporal Distribution of Gamma Ray Bursts.

Lingenfelter, Richard E.

1997-01-01

28

Effective atomic numbers of blue topaz at different gamma-rays energies obtained from Compton scattering technique  

NASA Astrophysics Data System (ADS)

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 ?-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.

Tuschareon, S.; Limkitjaroenporn, P.; Kaewkhao, J.

2014-03-01

29

Portable compton gamma-ray detection system  

SciTech Connect

A Compton scattered gamma-ray detector system. The system comprises a gamma-ray spectrometer and an annular array of individual scintillators. The scintillators are positioned so that they are arrayed around the gamma-ray spectrometer. The annular array of individual scintillators includes a first scintillator. A radiation shield is positioned around the first scintillator. A multi-channel analyzer is operatively connected to the gamma-ray spectrometer and the annular array of individual scintillators.

Rowland, Mark S. (Alamo, CA); Oldaker, Mark E. (Pleasanton, CA)

2008-03-04

30

Photon-induced positron annihilation lifetime spectroscopy using ultrashort laser-Compton-scattered gamma-ray pulses.  

PubMed

High-energy ultrashort gamma-ray pulses can be generated via laser Compton scattering with 90° collisions at the UVSOR-II electron storage ring. As an applied study of ultrashort gamma-ray pulses, a new photon-induced positron annihilation lifetime spectroscopy approach has been developed. Ultrashort gamma-ray pulses with a maximum energy of 6.6 MeV and pulse width of 2.2 ps created positrons throughout bulk lead via pair production. Annihilation gamma rays were detected by a BaF2 scintillator mounted on a photomultiplier tube. A positron lifetime spectrum was obtained by measuring the time difference between the RF frequency of the electron storage ring and the detection time of the annihilation gamma rays. We calculated the response of the BaF2 scintillator and the time jitter caused by the variation in the total path length of the ultrashort gamma-ray pulses, annihilation gamma rays, and scintillation light using a Monte Carlo simulation code. The positron lifetime for bulk lead was successfully measured. PMID:23742543

Taira, Y; Toyokawa, H; Kuroda, R; Yamamoto, N; Adachi, M; Tanaka, S; Katoh, M

2013-05-01

31

Photon-induced positron annihilation lifetime spectroscopy using ultrashort laser-Compton-scattered gamma-ray pulses  

NASA Astrophysics Data System (ADS)

High-energy ultrashort gamma-ray pulses can be generated via laser Compton scattering with 90° collisions at the UVSOR-II electron storage ring. As an applied study of ultrashort gamma-ray pulses, a new photon-induced positron annihilation lifetime spectroscopy approach has been developed. Ultrashort gamma-ray pulses with a maximum energy of 6.6 MeV and pulse width of 2.2 ps created positrons throughout bulk lead via pair production. Annihilation gamma rays were detected by a BaF2 scintillator mounted on a photomultiplier tube. A positron lifetime spectrum was obtained by measuring the time difference between the RF frequency of the electron storage ring and the detection time of the annihilation gamma rays. We calculated the response of the BaF2 scintillator and the time jitter caused by the variation in the total path length of the ultrashort gamma-ray pulses, annihilation gamma rays, and scintillation light using a Monte Carlo simulation code. The positron lifetime for bulk lead was successfully measured.

Taira, Y.; Toyokawa, H.; Kuroda, R.; Yamamoto, N.; Adachi, M.; Tanaka, S.; Katoh, M.

2013-05-01

32

Nondestructive detection of hidden chemical compounds with laser Compton-scattering gamma rays  

NASA Astrophysics Data System (ADS)

A nondestructive assay method for measuring a shielded chemical compound has been proposed. The chemical compound is measured by using a nuclear resonance fluorescence (NRF) measurement technique with an energy tunable laser Compton-scattering (LCS) ?-ray source. This method has an advantage that hidden materials can be detected through heavy shields such as iron plates of a thickness of several centimeters. A detection of a chemical compound of melamine, C3H6N6, shielded by 15-mm-thick iron and 4-mm-thick lead plates is demonstrated. The NRF ?-rays of 12C and 14N of the melamine are measured by using the LCS ?-rays of the energies of up to 5.0 MeV. The observed ratio (12C/14N)exp=0.39+/-0.12 is consistent with (C/N)melamine=0.5.

Hayakawa, Takehito; Ohgaki, Hideaki; Shizuma, Toshiyuki; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Minehara, Eisuke; Kii, Toshiteru; Toyokawa, Hiroyuki

2009-04-01

33

Polarimetry of short-pulse gamma rays produced through inverse Compton scattering of circularly polarized laser beams.  

PubMed

We have developed a polarimetry of ultrashort pulse gamma rays based on the fact that gamma rays penetrating in the forward direction through a magnetized iron carry information on the helicity of the original gamma rays. Polarized, short-pulse gamma rays of (1.1+/-0.2)x10(6)/bunch with a time duration of 31 ps and a maximum energy of 55.9 MeV were produced via Compton scattering of a circularly polarized laser beam of 532 nm off an electron beam of 1.28 GeV. The first demonstration of asymmetry measurements of short-pulse gamma rays was conducted using longitudinally magnetized iron of 15 cm length. It is found that the gamma-ray intensity is in good agreement with the simulated value of 1.0x10(6). Varying the degree of laser polarization, the asymmetry for 100% laser polarization was derived to be (1.29+/-0.12)%, which is also consistent with the expected value of 1.3%. PMID:14611407

Fukuda, M; Aoki, T; Dobashi, K; Hirose, T; Iimura, T; Kurihara, Y; Okugi, T; Omori, T; Sakai, I; Urakawa, J; Washio, M

2003-10-17

34

Weak Deeply Virtual Compton Scattering  

SciTech Connect

We extend the analysis of the deeply virtual Compton scattering process to the weak interaction sector in the generalized Bjorken limit. The virtual Compton scattering amplitudes for the weak neutral and charged currents are calculated at the leading twist within the framework of the nonlocal light-cone expansion via coordinate space QCD string operators. Using a simple model, we estimate cross sections for neutrino scattering off the nucleon, relevant for future high intensity neutrino beam facilities.

Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

2007-03-01

35

DESIGN OF A 250 MeV, X-BAND PHOTOINJECTOR LINAC FOR A PRECISION COMPTON-SCATTERING BASED GAMMA-RAY SOURCE  

Microsoft Academic Search

We present a compact, X-band, high-brightness accelerator design suitable for driving a precision gamma-ray source. Future applications of gamma-rays generated by Compton-scattering of laser and relativistic electron beams place stringent demands on the brightness and stability of the incident electron beam. This design identifies the beam parameters required for gamma-ray production, including position, and pointing stability. The design uses an

S G Anderson; F Albert; D J Gibson; D McNabb; M Messerly; B Rusnak; M Shverdin; F V Hartemann; C W Siders; C J Barty; S Tantawi; A Vlieks

2009-01-01

36

X-ray generation from slanting laser-Compton scattering for future energy-tunable Shanghai Laser Electron Gamma Source  

NASA Astrophysics Data System (ADS)

There is great interest in the generation of energy-tunable, bright, short-pulse X/ ?-ray sources, which are required in various research fields. Laser-Compton scattering (LCS) is considered to be one of the most promising methods to implement this kind of X/ ?-ray source. At the 100-MeV LINAC of the Shanghai Institute of Applied Physics, a 2-J, 8-ns, 1064-nm, Q-switched Nd:YAG laser is brought to a slanting collision at 40° (44°) with an 112-MeV, 0.9-ns (rms) relativistic electron beam. We measured the LCS X-ray energy spectrum with a peak energy of 31.73±0.22stat±1.64syst keV and a peak width (rms) of 0.74±0.26stat±0.03syst keV. This preliminary investigation was carried out to understand the feasibility of developing an energy-tunable X/ ?-ray source. Based on this study, the future Shanghai Laser Electron Gamma Source (SLEGS) at the Shanghai Synchrotron Radiation Facility (SSRF) can be constructed to be not only an energy-tunable ?-ray source by guiding the laser incident angle from laser-Compton scattering, but also a high flux (˜1010 photons/s or even higher) ?-ray source by adding a laser super-cavity.

Luo, W.; Xu, W.; Pan, Q. Y.; Cai, X. Z.; Chen, Y. Z.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Liu, W. H.; Lin, G. Q.; Ma, Y. G.; Shen, W. Q.; Shi, X. C.; Xu, B. J.; Xu, J. Q.; Xu, Y.; Zhang, H. O.; Yan, Z.; Yang, L. F.; Zhao, M. H.

2010-12-01

37

Compton Scattering Sources and Applications at LLNL  

SciTech Connect

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV {gamma}-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented.

Albert, Felicie; Anderson, S. G.; Anderson, G.; Bayramian, A.; Betts, S. M.; Cross, R. R.; Ebbers, C. A.; Gibson, D. J.; Marsh, R. A.; Messerly, M.; Shverdin, M. Y.; Wu, S. S.; Hartemann, F. V.; Scarpetti, R.; Siders, C. W.; Barty, C. P. J. [Lawrence Livermore National Laboratory, NIF and Photon Science, 7000 East Avenue, Livermore, CA, 94550 (United States)

2010-11-04

38

Production of gamma-rays by inverse Compton scattering in jets.  

NASA Astrophysics Data System (ADS)

We discuss a model for the ?-ray production in blazars in which electrons are accelerated rectilinearly in localised regions of the jet, scattering soft radiation from the accretion disk. In our model the jet divides naturally into two zones. In the `radiation dominated zone' (close to the disk), the acceleration of electrons is balanced by inverse Compton losses in the Thomson regime and energy is efficiently transferred into the ?-rays. The ?-ray spectral slope is determined by the electric field profile along the jet. In the `particle dominated zone' (further from the disk) the electron losses are too low to balance acceleration and the electrons are injected into the jet with energies corresponding to the full potential drop in the acceleration region. We suggest that these electrons are then isotropised by the random component of the magnetic field of the jet and cool mainly by synchrotron losses. In the framework of our model we predict further that Galactic black hole candidates might be sources of ?-radiation; in this case, however, we do not expect emission above 10GeV.

Bednarek, W.; Kirk, J. G.; Mastichiadis, A.

1996-12-01

39

Nonlinear Brightness Optimization in Compton Scattering  

NASA Astrophysics Data System (ADS)

In Compton scattering light sources, a laser pulse is scattered by a relativistic electron beam to generate tunable x and gamma rays. Because of the inhomogeneous nature of the incident radiation, the relativistic Lorentz boost of the electrons is modulated by the ponderomotive force during the interaction, leading to intrinsic spectral broadening and brightness limitations. These effects are discussed, along with an optimization strategy to properly balance the laser bandwidth, diffraction, and nonlinear ponderomotive force.

Hartemann, Fred V.; Wu, Sheldon S. Q.

2013-07-01

40

Nonlinear brightness optimization in compton scattering.  

PubMed

In Compton scattering light sources, a laser pulse is scattered by a relativistic electron beam to generate tunable x and gamma rays. Because of the inhomogeneous nature of the incident radiation, the relativistic Lorentz boost of the electrons is modulated by the ponderomotive force during the interaction, leading to intrinsic spectral broadening and brightness limitations. These effects are discussed, along with an optimization strategy to properly balance the laser bandwidth, diffraction, and nonlinear ponderomotive force. PMID:23931374

Hartemann, Fred V; Wu, Sheldon S Q

2013-07-26

41

Energy and intensity distributions of multiple Compton scattering of 0.279-, 0.662-, and 1.12-MeV {gamma} rays  

SciTech Connect

Multiple Compton scattering results in an incorrect evaluation of Compton profile, which usually examines the case when the photon has undergone only one Compton collision in the sample. The probability of a photon being scattered several times may be significant for a target of finite dimensions both in depth and lateral dimensions. The present measurements are carried out to study the energy and intensity distributions of 0.279, 0.662, and 1.12 MeV {gamma} rays multiply scattered from the copper target of various thicknesses at a scattering angle of 60 degree sign . The scattered photons are detected by a NaI(Tl) scintillation detector whose detector response unfolding, converting the pulse-height distribution to a photon energy spectrum, is obtained with the help of an inverse response matrix. We observe that with an increase in target thickness, the number of multiply scattered photons saturates at a particular value of the target thickness (saturation depth). The multiply scattered fraction starts saturating above a particular energy window around the centroid of inelastic scattered peak. The signal-to-noise ratio is found to be decreasing with an increase in target thickness. Monte Carlo calculations based upon the package developed by Bauer and Pattison [Comptom Scattering Experiments at the HMI (1981), HMI-B 364, pp. 1-106] support the present experimental results.

Singh, Manpreet; Singh, Gurvinderjit; Singh, Bhajan; Sandhu, B. S. [Physics Department, Punjabi University, Patiala-147002 (India)

2006-10-15

42

THE ROLE OF INVERSE COMPTON SCATTERING IN SOLAR CORONAL HARD X-RAY AND {gamma}-RAY SOURCES  

SciTech Connect

Coronal hard X-ray (HXR) and continuum {gamma}-ray sources associated with the impulsive phase of solar flares have been the subject of renewed interest in recent years. They have been interpreted in terms of thin-target, non-thermal bremsstrahlung emission. This interpretation has led to rather extreme physical requirements in some cases. For example, in one case, essentially all of the electrons in the source must be accelerated to non-thermal energies to account for the coronal HXR source. In other cases, the extremely hard photon spectra of the coronal continuum {gamma}-ray emission suggest that the low-energy cutoff of the electron energy distribution lies in the MeV energy range. Here, we consider the role of inverse Compton scattering (ICS) as an alternate emission mechanism in both the ultra- and mildly relativistic regimes. It is known that relativistic electrons are produced during powerful flares; these are capable of upscattering soft photospheric photons to HXR and {gamma}-ray energies. Previously overlooked is the fact that mildly relativistic electrons, generally produced in much greater numbers in flares of all sizes, can upscatter extreme-ultraviolet/soft X-ray photons to HXR energies. We also explore ICS on anisotropic electron distributions and show that the resulting emission can be significantly enhanced over an isotropic electron distribution for favorable viewing geometries. We briefly review results from bremsstrahlung emission and reconsider circumstances under which non-thermal bremsstrahlung or ICS would be favored. Finally, we consider a selection of coronal HXR and {gamma}-ray events and find that in some cases the ICS is a viable alternative emission mechanism.

Chen Bin [Department of Astronomy, University of Virginia, Charlottesville, VA 22904 (United States); Bastian, T. S. [National Radio Astronomy Observatory, Charlottesville, VA 22903 (United States)

2012-05-01

43

Timelike Compton Scattering with CLAS  

NASA Astrophysics Data System (ADS)

Deeply Virtual Compton Scattering (DVCS), Epg, has been under intense theoretical and experimental studies in recent years as a new tool to access Generalized Parton Distributions (GPDs) of the nucleon. The simplest observables in DVCS for studying GPDs are spin dependent cross section differences. These asymmetries measure the imaginary part of Compton Form-Factors (CFFs), where GPDs enter at specific kinematical point, ?=x. Here ? is the generalized Bjorken variable and x is the light-cone momentum fraction of the struck quark. The real part of CFF is proportional to the integral of GPDs over x and can only be accessed in the measurements of the DVCS cross section or the beam charge asymmetry. Studying the real part is important for modeling GPDs. It is sensitive to the so-called D-term, introduced in the modeling of GPDs to ensure the polynomiality of their Mellin moments. Photoproduction of lepton pairs, or so-called Time-like Compton Scattering (TCS), is an inverse process to DVCS and offers additional constraints on GPDs. In particular, TCS can be used as an effective tool to study the real part of the Compton amplitude using the azimuthal angular asymmetry arising from exchange of l^+ and l^- momenta. In this report, first analysis of the Time-like Compton Scattering using the CLAS electroproduction data will be presented. Details of the extraction of quasi-real photoproduction of lepton pairs will be discussed.

Stepanyan, Stepan

2009-10-01

44

Can the cosmic x ray and gamma ray background be due to reflection of a steep power law spectrum and Compton scattering by relativistic electrons?  

NASA Technical Reports Server (NTRS)

We reconsider the recent model for the origin in the cosmic X-ray and gamma-ray background by Rogers and Field. The background in the model is due to an unresolved population of AGNs. An individual AGN spectrum contains three components: a power law with the energy index of alpha = 1.1, an enhanced reflection component, and a component from Compton scattering by relativistic electrons with a low energy cutoff at some minimum Lorentz factor, gamma(sub min) much greater than 1. The MeV bump seen in the gamma-ray background is then explained by inverse Compton emission by the electrons. We show that the model does not reproduce the shape of the observed X-ray and gamma-ray background below 10 MeV and that it overproduces the background at larger energies. Furthermore, we find the assumptions made for the Compton component to be physically inconsistent. Relaxing the inconsistent assumptions leads to model spectra even more different from that of the observed cosmic background. Thus, we can reject the hypothesis that the high-energy cosmic background is due to the described model.

Zycki, Piotr T.; Zdziarski, Andrzej A.; Svensson, Roland

1991-01-01

45

Prototype design of multiple Compton gamma-ray camera  

Microsoft Academic Search

The authors found that the first Compton scattering of the gamma-ray energy degrading process can be correctly reconstructed with a high probability, if energies and positions of recoil electrons are recorded within a few keV (rms) and approx. =1X1X1mm³ for the first 4-5 steps. Such a device, called the Multiple Compton Gamma-ray Camera, allows us to measure the energy, direction,

T. Kamae; N. Hanada; R. Enomoto

1988-01-01

46

Design of a 2 MeV Compton scattering gamma-ray source for DNDO missions  

SciTech Connect

Nuclear resonance fluorescence-based isotope-specific detection and imaging is a powerful new technology that can enable access to new mission spaces for DNDO. Within this context, the development of advanced mono-energetic gamma ray sources plays an important role in the DNDO R&D portfolio, as it offers a faster, more precise, and safer alternative to conventional Bremsstrahlung sources. In this report, a specific design strategy is presented, along with a series of theoretical and computational tools, with the goal of optimizing source parameters for DNDO applications. In parallel, key technologies are outlined, along with discussions justifying specific choices and contrasting those with other alternatives. Finally, a complete conceptual design is described, and machine parameters are presented in detail.

Hartemann, F V; Albert, F

2009-08-24

47

Elastic Compton Scattering from Carbon  

NASA Astrophysics Data System (ADS)

The elastic Compton scattering cross section for carbon has been measured using tagged photons at the MAX-Lab facility in Lund, Sweden. To produce the photons, an electron beam impinged on an aluminum foil -- the electrons radiated via bremsstrahlung and then entered a magnetic spectrometer which deflected them onto a plastic scintillator array in the spectrometer focal plane. The produced photons (E? = 95-115 MeV) scattered from a graphite block and were detected at 3 angles (?? = 60 , 120 , 150 ) by high-resolution large-volume NaI detectors. Using timing information from the focal-plane scintillators, coincidences between converted electrons and scattered photons were identified, thereby ``tagging'' the energy of the incident photons. The elastic Compton peak was then observed in the energy spectrum of the NaI detectors. After subtracting random backgrounds due to cosmic rays and untagged photons, the resulting energy spectrum showed a clear peak sitting on a low-energy background. Accounting for this background with an exponential fit, the integral of the peak yielded the number of scattered photons in each NaI. The absolute cross section was determined from these yields using information about the photon beam flux, the target thickness and the detector solid angles. These data for the carbon cross section will be presented, and the energy and angle dependencies will be discussed.

Lewis, Kasey; Feldman, Gerald

2009-05-01

48

Deeply virtual compton scattering off the neutron.  

PubMed

The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e,e'gamma)X cross section measured at Q2=1.9 GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to E_{q}, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced. PMID:18233443

Mazouz, M; Camsonne, A; Camacho, C Muñoz; Ferdi, C; Gavalian, G; Kuchina, E; Amarian, M; Aniol, K A; Beaumel, M; Benaoum, H; Bertin, P; Brossard, M; Chen, J-P; Chudakov, E; Craver, B; Cusanno, F; de Jager, C W; Deur, A; Feuerbach, R; Fieschi, J-M; Frullani, S; Garçon, M; Garibaldi, F; Gayou, O; Gilman, R; Gomez, J; Gueye, P; Guichon, P A M; Guillon, B; Hansen, O; Hayes, D; Higinbotham, D; Holmstrom, T; Hyde, C E; Ibrahim, H; Igarashi, R; Jiang, X; Jo, H S; Kaufman, L J; Kelleher, A; Kolarkar, A; Kumbartzki, G; Laveissiere, G; Lerose, J J; Lindgren, R; Liyanage, N; Lu, H-J; Margaziotis, D J; Meziani, Z-E; McCormick, K; Michaels, R; Michel, B; Moffit, B; Monaghan, P; Nanda, S; Nelyubin, V; Potokar, M; Qiang, Y; Ransome, R D; Réal, J-S; Reitz, B; Roblin, Y; Roche, J; Sabatié, F; Saha, A; Sirca, S; Slifer, K; Solvignon, P; Subedi, R; Sulkosky, V; Ulmer, P E; Voutier, E; Wang, K; Weinstein, L B; Wojtsekhowski, B; Zheng, X; Zhu, L

2007-12-14

49

INVERSE COMPTON SCATTERING MODEL FOR X-RAY EMISSION OF THE GAMMA-RAY BINARY LS 5039  

SciTech Connect

We propose a model for the gamma-ray binary LS 5039 in which the X-ray emission is due to the inverse Compton (IC) process instead of the synchrotron radiation. Although the synchrotron model has been discussed in previous studies, it requires a strong magnetic field which leads to a severe suppression of the TeV gamma-ray flux in conflict with H.E.S.S. observations. In this paper, we calculate the IC emission by low energy electrons ({gamma}{sub e} {approx}< 10{sup 3}) in the Thomson regime. We find that IC emission of the low energy electrons can explain the X-ray flux and spectrum observed with Suzaku if the minimum Lorentz factor of injected electrons {gamma}{sub min} is around 10{sup 3}. In addition, we show that the Suzaku light curve is well reproduced if {gamma}{sub min} varies in proportion to the Fermi flux when the distribution function of injected electrons at higher energies is fixed. We conclude that the emission from LS 5039 is well explained by the model with the IC emission from electrons whose injection properties are dependent on the orbital phase. Since the X-ray flux is primarily determined by the total number of cooling electrons, this conclusion is rather robust, although some mismatches between the model and observations at the GeV band remain in the present formulation.

Yamaguchi, M. S.; Takahara, F. [Department of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)

2012-12-20

50

Determination of Rest Mass Energy of the Electron by a Compton Scattering Experiment  

ERIC Educational Resources Information Center

We report here a simple Compton scattering experiment which may be carried out in graduate and undergraduate laboratories to determine the rest mass energy of the electron. In the present experiment, we have measured the energies of the Compton scattered gamma rays with a NaI(Tl) gamma ray spectrometer coupled to a 1 K multichannel analyzer at…

Prasannakumar, S.; Krishnaveni, S.; Umesh, T. K.

2012-01-01

51

Three-dimensional theory of weakly nonlinear Compton scattering  

NASA Astrophysics Data System (ADS)

Nonlinear effects are known to occur in light sources when the wiggler parameter, or normalized 4-potential, A=e-A?A?/m0c, approaches unity. In this paper, it is shown that nonlinear spectral features can appear at arbitrarily low values of A if the fractional bandwidth of the undulator, ??-1, is sufficiently small and satisfies the condition A2??~1. Consequences for the spectral brightness of Compton scattering light sources are outlined. Compton and Thomson scattering theories are compared with the Klein-Nishina cross-section formula to highlight differences in the case of narrow band gamma-ray operation. A weakly nonlinear Compton scattering theory is developed in one (plane wave) and three (local plane wave approximation) dimensions. Analytical models are presented and benchmarked against numerical calculations solving the Lorentz force equation with a fourth-order Runge-Kutta algorithm. Finally, narrow band gamma-ray spectra are calculated for realistic laser and electron beams.

Albert, F.; Anderson, S. G.; Gibson, D. J.; Marsh, R. A.; Siders, C. W.; Barty, C. P. J.; Hartemann, F. V.

2011-01-01

52

Real Compton scattering via color dipoles  

SciTech Connect

We study the photoabsorption reaction and real Compton scattering within the color dipole model. We rely on a photon wave function derived in the instanton-vacuum model and on the energy-dependent phenomenological elastic dipole amplitude. Data for the photoabsorption cross section at high energies agree with our parameter-free calculations. We also provide predictions for the differential real Compton scattering cross section. Although no data for small angle Compton scattering are available so far, this process can be measured in ultraperipheral hadronic and nuclear collisions at the LHC.

Kopeliovich, B. Z. [Departamento de Fisica, Centro de Estudios Subatomicos, y Centro Cientifico-Tecnologico de Valparaiso, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile); Joint Institute for Nuclear Research, Dubna (Russian Federation); Schmidt, Ivan; Siddikov, M. [Departamento de Fisica, Centro de Estudios Subatomicos, y Centro Cientifico-Tecnologico de Valparaiso, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Valparaiso (Chile)

2009-09-01

53

Inverse Compton Scattering Model for X-Ray Emission of the Gamma-Ray Binary LS 5039  

NASA Astrophysics Data System (ADS)

We propose a model for the gamma-ray binary LS 5039 in which the X-ray emission is due to the inverse Compton (IC) process instead of the synchrotron radiation. Although the synchrotron model has been discussed in previous studies, it requires a strong magnetic field which leads to a severe suppression of the TeV gamma-ray flux in conflict with H.E.S.S. observations. In this paper, we calculate the IC emission by low energy electrons (? e <~ 103) in the Thomson regime. We find that IC emission of the low energy electrons can explain the X-ray flux and spectrum observed with Suzaku if the minimum Lorentz factor of injected electrons ?min is around 103. In addition, we show that the Suzaku light curve is well reproduced if ?min varies in proportion to the Fermi flux when the distribution function of injected electrons at higher energies is fixed. We conclude that the emission from LS 5039 is well explained by the model with the IC emission from electrons whose injection properties are dependent on the orbital phase. Since the X-ray flux is primarily determined by the total number of cooling electrons, this conclusion is rather robust, although some mismatches between the model and observations at the GeV band remain in the present formulation.

Yamaguchi, M. S.; Takahara, F.

2012-12-01

54

Gamma Scattering.  

National Technical Information Service (NTIS)

Experimental examinations have been performed on a gamma scattering source/detector configuration that is believed to have the potential for providing density information at a finite number of positions along the primary beam and the average attenuation a...

A. G. Baker

1980-01-01

55

Experimental Study of Energy Distribution in Double Photon Compton Scattering  

SciTech Connect

The energy distribution of gamma photons scattered in double photon Compton scattering is measured experimentally for 0.662-MeV incident gamma photons. The two simultaneously emitted gamma quanta are investigated using a slow-fast coincidence technique. The experimental data on energy distribution do not suffer from inherent energy resolution of the gamma detector and confirm the continuous nature of energy spectra for the emitted photons. The present results are in agreement with the current theory of this higher-order process.

Dewan, R.; Saddi, M.B.; Sandhu, B.S.; Singh, B.; Ghumman, B.S. [Punjabi University (India)

2002-06-15

56

Half-life of the {sup 164}Ho by the ({gamma},n) reaction from laser Compton scattering {gamma} rays at the electron storage ring NewSUBARU  

SciTech Connect

The half-life of an isomer in {sup 164}Ho was measured by using photodisintegration reactions. The photons were generated by Compton scattering of laser photons and relativistic electrons at the electron storage ring NewSUBARU in the super photon ring 8-GeV (SPring-8) facility. The half-life is 36.4{+-}0.3 min. This value is about 3% shorter than the previous value 37.5{sub -0.5}{sup +1.5} min reported in 1966.

Hayakawa, T. [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan); Shizuma, T.; Mori, M.; Kawase, K.; Kando, M.; Kikuzawa, N. [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); Miyamoto, S.; Amano, S.; Horikawa, K.; Ishihara, K.; Mochizuki, T. [University of Hyogo, Hyogo 678-1205 (Japan); Chiba, S. [Advanced Research Center, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan); Kajino, T. [National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan); Department of Astronomy, School of Science, University of Tokyo, Tokyo 113-0033 (Japan); Fujiwara, M. [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan)

2008-06-15

57

Gamma scattering  

SciTech Connect

Experimental examinations have been performed on a gamma scattering source/detector configuration that is believed to have the potential for providing density information at a finite number of positions along the primary beam and the average attenuation along the exit rays from those positions. Scattering spectra were acquired for several void-fluid density distribution simulations. The multiple-scattered photon contribution to the total acquired spectrum from a water-filled pipe simulation was extracted and found to be between 18 to 33% of the total counts in the single-scattered photon energy region, with a region average of 24%.

Baker, A.G.

1980-01-01

58

An Electromagnetic Calorimeter for the JLab Real Compton Scattering Experiment  

Microsoft Academic Search

A lead-glass hodoscope calorimeter that was constructed for use in the Jefferson Lab Real Compton Scattering experiment is described. The detector provides a measurement of the coordinates and the energy of scattered photons in the GeV energy range with resolutions of 5 mm and 6%\\/\\\\sqrt(E{\\\\gamma} [GeV]). Features of both the detector design and its performance in the high luminosity environment

D. J. Hamilton; A. Shahinyan; B. Wojtsekhowski; J. R. M. Annand; T.-H. Chang; E. Chudakov; A. Danagoulian; P. Degtyarenko; K. Egiyan; R. Gilman; V. Gorbenko; J. Hines; E. Hovhannisyan; C. E. Hyde-Wright; C. W. de Jager; A. Ketikyan; V. H. Mamyan; R. Michaels; A. M. Nathan; V. Nelyubin; I. Rachek; M. Roedelbrom; A. Petrosyan; R. Pomatsalyuk; V. Popov; J. Segal; Y. Shestakov; J. Templon; H. Voskanyan

2007-01-01

59

The nonlinear effect in relativistic Compton scattering for an intense circularly polarized laser  

NASA Astrophysics Data System (ADS)

Compton scattering between an intense laser pulse and a relativistic electron beam offers a promising development path toward high-energy, high-brightness x- and gamma-ray sources. Increasing laser peak power to obtain intense x- and gamma rays causes nonlinear Compton scattering to occur. To predict high-order harmonic radiation properties, we upgrade a Monte Carlo laser-Compton scattering simulation code (MCLCSS) by taking into account the nonlinear effect for the relativistic Compton scattering process. The energy spectra and angular and harmonic intensity distributions of the scattered photons are investigated using nonlinear Compton scattering of an intense circularly polarized laser. It is found that the laser parameter {{a}_{0}}\\equiv e{\\rm{A}}\\;{{m}_{e}}{{c}^{-2}} plays an important role in the generation of high-order harmonic radiation. Our study also suggests that the high-energy tails of the second and higher harmonics will stray from the backscattering region.

Luo, W.; Zhuo, H. B.; Ma, Y. Y.; Zhu, Z. C.; Fan, G. T.; Xu, W.; Song, Y. M.

2014-07-01

60

Gamma-Ray Polarimetry with Compton Telescope  

SciTech Connect

Compton telescope is a promising technology to achieve very high sensitivity in the soft gamma-ray band (0.1-10 MeV) by utilizing Compton kinematics. Compton kinematics also enables polarization measurement which will open new windows to study gamma-ray production mechanism in the universe. CdTe and Si semiconductor technologies are key technologies to realize the Compton telescope in which their high energy resolution is crucial for high angular resolution and background rejection capability. We have assembled a prototype module using a double-sided silicon strip detector and CdTe pixel detectors. In this paper, we present expected polarization performance of a proposed mission (NeXT/SGD). We also report results from polarization measurements using polarized synchrotron light and validation of EGS4 MC simulation.

Tajima, H

2004-07-06

61

Compact Laser Technology for Compton Scattering Sources  

NASA Astrophysics Data System (ADS)

We describe compact laser technology for Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering light source at LLNL. The high energy, 120W interaction laser utilizes chirped pulse amplification (CPA) in Nd:YAG to amplify a sub-nanometer bandwidth 20 ?J pulses from a fiber system to 1J. A novel pulse stretcher provides a dispersion of over 7000ps/nm to expand a several picosecond wide seed pulse to 6ns. After amplification, the pulse is recompressed to 10ps with a hyper-dispersive pulse compressor. We also describe a technique for over an order of magnitude increase in the generated gamma-ray flux by recirculation of the interaction laser pulse. This technique, termed Recirculation Injection by Nonlinear Gating (RING), consists of frequency doubling the incident laser pulse inside a dichroic mirror cavity. The resonator mirrors transmit at 1? and reflect at 2?. The 2^nd harmonic of the incident pulse then becomes trapped inside the cavity. To date, we demonstrated 14 times cavity enhancement of 180mJ, 10ps, 532nm laser pulses.

Shverdin, M.; Albert, F.; Anderson, S. G.; Bayramian, A.; Betts, S. M.; Ebbers, C.; Gibson, D.; Messerly, M.; Hartemann, F. V.; Siders, C. W.; McNabb, D. P.; Barty, C. P. J.

2009-11-01

62

Prototype design of multiple compton gamma-ray camera  

SciTech Connect

The authors found that the first Compton scattering of the gamma-ray energy degrading process can be correctly reconstructed with a high probability, if energies and positions of recoil electrons are recorded within a few keV (rms) and approx. =1X1X1mm/sup 3/ for the first 4-5 steps. Such a device, called the Multiple Compton Gamma-ray Camera, allows us to measure the energy, direction, and polarization of gamma-rays in sub-MeV to few MeV range. The authors present here the design of a prototype optimized to 150-600keV gamma-rays. Monte Carlo studies of the design predict that one gets a high detection efficiency, a high polarization analyzing power, and a reasonable angular resolution without collimators.

Kamae, T.; Hanada, N.; Enomoto, R.

1988-02-01

63

High Power Picosecond Laser Pulse Recirculation for Compton Scattering  

NASA Astrophysics Data System (ADS)

Gamma-ray generation by Compton back-scattering laser photons off a relativistic electron beam suffers from a small Thomson cross-section. Recirculating unused laser photons can increase the average gamma-ray flux. Traditional approaches to laser recirculation rely on either resonant coupling of a low-energy pulse train to a cavity or active pulse switching using a pockels cell. Our alternative, passive approach does not require interferometeric alignment accuracy and is compatible with ultrashort, high peak power pulses. Pulse injection is achieved by a thin frequency converter inside the cavity in the path of the incident beam. The cavity consists of dichroic mirrors that transmit the incident but reflect the frequency-converted light. Initial modeling and experiments predict better than 20 times increase in the average brightness of Compton back-scattering sources with our pulse recirculation method.

Shverdin, M.; Anderson, S.; Brown, C.; Betts, S.; Gibson, D.; Hernandez, J.; Johnson, M.; Jovanovic, I.; McNabb, D.; Messerly, M.; Pruet, J.; Tremaine, A.; Hartemann, F.; Siders, C.; Barty, C. P. J.

2007-11-01

64

Program of Compton Scattering Studies on the Deuteron at HIGS  

NASA Astrophysics Data System (ADS)

The High Intensity Gamma Source (HIGS) at Duke University will deliver intense mono-energetic photon beams with high degrees of linear or circular polarization by backscattering of free-electron laser (FEL) photons. To exploit the unique capabilities of this facility, a program of Compton scattering studies on light nuclei (p, d, ^3He) is planned. Experiments using deuterium targets will elucidate the electromagnetic polarizabilities of the neutron (?n and ?n) and provide high precision data at low energies (E? = 30-50 MeV) for comparison with chiral Effective Field Theory (EFT) calculations. Absolute cross sections for elastic Compton scattering on deuterium will be measured for the first time in this energy region, and with the advent of polarized deuterium targets at HIGS, additional constraints on ?n and ?n can be imposed. Furthermore, the prospect of measuring double polarization observables with circularly polarized photons in Compton scattering at higher energies (E? = 100-120 MeV) will enable the spin polarizabilities (?1, ?2, ?3, ?4) of the neutron to be determined for the first time and will complement parallel studies on the proton. The plans for Compton scattering experiments on deuterium will be outlined and the impact on the neutron electromagnetic and spin polarizabilities will be discussed. )

Feldman, Gerald

2010-02-01

65

Compton scatter transition radiation detectors for ACCESS  

NASA Astrophysics Data System (ADS)

The detection of transition radiation x-rays can provide a direct, non-destructive measurement of a particle's Lorentz factor. Standard transition radiation detectors (TRDs) typically incorporate thin plastic foil radiators and gas-filled x-ray detectors, and are sensitive up to ? ~ 104. To reach higher Lorentz factors (up to ? ~ 105), thicker, denser radiators can be used, which consequently produce x-rays of harder energies (? 100 keV). At these energies, scintillator detectors are more efficient in detecting the hard x-rays, and Compton scattering of the x-rays out of the path of the particle becomes an important effect. The Compton scattering can be utilized to separate the transition radiation from the ionization background spatially. We have designed and built a Compton Scatter TRD optimized for high Lorentz factors and exposed it to the electron beam at the CERN SPS. In this paper, we discuss the design principles for a high energy TRD; present preliminary results of the accelerator tests, demonstrating the effectiveness of the Compton Scatter TRD approach; and finally, discuss the application of this technique to the ACCESS cosmic-ray mission.

Case, Gary L.; Cherry, Michael L.

2004-01-01

66

Compton Scattering Sources and Applications at LLNL  

NASA Astrophysics Data System (ADS)

We report the design and current status of a monoenergetic laser-based Compton scattering 0.5-2.5 MeV ?-ray source. Previous nuclear resonance fluorescence results and future linac and laser developments for the source are presented.

Albert, Felicie; Anderson, S. G.; Anderson, G.; Bayramian, A.; Betts, S. M.; Cross, R. R.; Ebbers, C. A.; Gibson, D. J.; Marsh, R. A.; Messerly, M.; Shverdin, M. Y.; Wu, S. S.; Hartemann, F. V.; Scarpetti, R.; Siders, C. W.; Barty, C. P. J.

2010-11-01

67

Low-Energy Proton Compton Scattering.  

National Technical Information Service (NTIS)

Low-energy proton Compton scattering is investigated in the isobar model taking into account the constraint equations of the Prange invariant amplitudes. It is shown that the delta (1230) and N*(1520) resonances together with the pion pole are adequate to...

A. M. Harun ar Rashid T. K. Chaudhury

1983-01-01

68

Resonant Compton scattering associated with pair creation  

NASA Astrophysics Data System (ADS)

Studies of Compton scattering by relativistic electrons in a strong magnetic field have been restricted to either incident photon angles ?' aligned along the magnetic field B or incident photon energies ?' below the first pair creation threshold . When these restrictions are relaxed there is a resonance in Compton scattering associated with pair creation (PC), that is analogous to but independent of known resonances associated with gyromagnetic absorption (GA). As with the GA resonances, that may be labeled by the Landau quantum numbers of the relevant states, there is a sequence of PC resonances where the scattering cross section diverges. In this paper, the lowest divergence is studied for incident photon energies satisfying ?'2sin2 ?'/(2 eB)?1, assuming that the scattering electron is in its ground (Landau) state. This lowest resonance affects only parallel-polarized photons.

Weise, Jeanette I.

2014-06-01

69

THEORY OF COMPTON SCATTERING BY ANISOTROPIC ELECTRONS  

SciTech Connect

Compton scattering plays an important role in various astrophysical objects such as accreting black holes and neutron stars, pulsars, relativistic jets, and clusters of galaxies, as well as the early universe. In most of the calculations, it is assumed that the electrons have isotropic angular distribution in some frame. However, there are situations where the anisotropy may be significant due to the bulk motions, or where there is anisotropic cooling by synchrotron radiation or an anisotropic source of seed soft photons. Here we develop an analytical theory of Compton scattering by anisotropic distribution of electrons that can significantly simplify the calculations. Assuming that the electron angular distribution can be represented by a second-order polynomial over the cosine of some angle (dipole and quadrupole anisotropies), we integrate the exact Klein-Nishina cross section over the angles. Exact analytical and approximate formulae valid for any photon and electron energies are derived for the redistribution functions describing Compton scattering of photons with arbitrary angular distribution by anisotropic electrons. The analytical expressions for the corresponding photon scattering cross section on such electrons, as well as the mean energy of scattered photons, its dispersion, and radiation pressure force are also derived. We apply the developed formalism to the accurate calculations of the thermal and kinematic Sunyaev-Zeldovich effects for arbitrary electron distributions.

Poutanen, Juri [Astronomy Division, Department of Physics, P.O. Box 3000, 90014 University of Oulu (Finland); Vurm, Indrek, E-mail: juri.poutanen@oulu.f, E-mail: indrek.vurm@oulu.f [Also at Tartu Observatory, 61602 Toravere, Tartumaa, Estonia. (Estonia)

2010-08-15

70

Three-dimensional theory of weakly nonlinear Compton scattering  

SciTech Connect

Nonlinear effects are known to occur in light sources when the wiggler parameter, or normalized 4-potential, A=e{radical}(-A{sub {mu}}A{sup {mu}})/m{sub 0}c, approaches unity. In this paper, it is shown that nonlinear spectral features can appear at arbitrarily low values of A if the fractional bandwidth of the undulator, {Delta}{phi}{sup -1}, is sufficiently small and satisfies the condition A{sup 2{Delta}{phi}{approx}}1. Consequences for the spectral brightness of Compton scattering light sources are outlined. Compton and Thomson scattering theories are compared with the Klein-Nishina cross-section formula to highlight differences in the case of narrow band gamma-ray operation. A weakly nonlinear Compton scattering theory is developed in one (plane wave) and three (local plane wave approximation) dimensions. Analytical models are presented and benchmarked against numerical calculations solving the Lorentz force equation with a fourth-order Runge-Kutta algorithm. Finally, narrow band gamma-ray spectra are calculated for realistic laser and electron beams.

Albert, F.; Anderson, S. G.; Gibson, D. J.; Marsh, R. A.; Siders, C. W.; Barty, C. P. J.; Hartemann, F. V. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2011-01-15

71

Inverse Compton scattering in anisotropic synchrotron sources  

NASA Astrophysics Data System (ADS)

Models of compact, high brightness temperature sources such as quasars and active galactic nuclei often predict substantial inverse-Compton scattered flux to be produced at high frequencies. As these fluxes are not observed, it is necessary to assume that extreme relativistic and/or anisotropic effects dominate the source. The often used equations to include these effects, however, are derived with several simplifying assumptions, which may not always be consistent with the derived source parameters (for example, the assumption of no time dependence in a violently variable quasar may not be appropriate). An explicit derivation of the dependence of the rate of inverse Compton scattering on anisotropies in the source is therefore here presented to emphasise the importance and number of assumptions required in the derivation.

Gilmore, G.

1981-10-01

72

Nucleon Compton scattering in perturbative QCD  

NASA Astrophysics Data System (ADS)

We have computed the helicity amplitudes for the reactions ?N-->?N (N=p,n) at large momentum transfer to lowest order in perturbative QCD. Our cross section for proton Compton scattering shows good qualitative agreement with experimental data, when the proton is modeled by the Chernyak-Oglobin-Zhitnitsky, King-Sachrajda, or Gari-Stefanis distribution amplitude. Discrepancies between our results and previous calculations seem to be due to different treatments of numerical integration around singularities.

Kronfeld, A. S.; Nii?, B.

1991-12-01

73

Observation of Nonlinear Effects in Compton Scattering  

Microsoft Academic Search

Nonlinear Compton scattering has been observed in the collision of a low-emittance 46.6-GeV electron beam with terawatt pulses from a Nd:glass laser at 1054 and 527 nm wavelengths in an experiment at the Final Focus Test Beam at SLAC. Peak laser intensities of 1018 W\\/cm2 have been achieved, corresponding to a value of 0.6 for the parameter eta = eErms\\/momega0c.

C. Bula; K. T. McDonald; E. J. Prebys; C. Bamber; S. Boege; T. Kotseroglou; A. C. Melissinos; D. D. Meyerhofer; W. Ragg; D. L. Burke; R. C. Field; G A Horton-Smith; A. C. Odian; J. E. Spencer; D. Walz; S. C. Berridge; W. M. Bugg; K D Shmakov; A. W. Weidemann

1996-01-01

74

The virtual Compton scattering at TJNAF  

SciTech Connect

The Virtual Compton Scattering is a powerful tool to probe the internal structure of the proton. A VCS experiment (E93050) was performed in Hall A at JLAB below and above the pion threshold. In the resonance region, cross sections of pion and photon electroproduction have been produced; below the pion threshold, evidence of the effect of the polarisabilities on the cross sections has been proved.

Rachele Di Salvo for the Hall A Collaboration

2002-02-01

75

Development of Compton gamma-ray sources at LLNL  

NASA Astrophysics Data System (ADS)

Compact Compton scattering gamma-ray sources offer the potential of studying nuclear photonics with new tools. The optimization of such sources depends on the final application, but generally requires maximizing the spectral density (photons/eV) of the gamma-ray beam while simultaneously reducing the overall bandwidth on target to minimize noise. We have developed an advanced design for one such system, comprising the RF drive, photoinjector, accelerator, and electron-generating and electron-scattering laser systems. This system uses a 120 Hz, 250 pC, 2 ps, 0.35 mm mrad electron beam with 250 MeV maximum energy in an X-band accelerator scattering off a 150 mJ, 10 ps, 532 nm laser to generate 5 × 1010 photons/eV/s/Sr at 0.5 MeV with an overall bandwidth of less than 1%. The source will be able to produce photons up to energies of 2.5 MeV. We also discuss Compton scattering gamma-ray source predictions given by numerical codes.

Albert, F.; Anderson, S. G.; Ebbers, C. A.; Gibson, D. J.; Hartemann, F. V.; Marsh, R. A.; Messerly, M. J.; Prantil, M. A.; Wu, S.; Barty, C. P. J.

2012-12-01

76

Development of Compton gamma-ray sources at LLNL  

SciTech Connect

Compact Compton scattering gamma-ray sources offer the potential of studying nuclear photonics with new tools. The optimization of such sources depends on the final application, but generally requires maximizing the spectral density (photons/eV) of the gamma-ray beam while simultaneously reducing the overall bandwidth on target to minimize noise. We have developed an advanced design for one such system, comprising the RF drive, photoinjector, accelerator, and electron-generating and electron-scattering laser systems. This system uses a 120 Hz, 250 pC, 2 ps, 0.35 mm mrad electron beam with 250 MeV maximum energy in an X-band accelerator scattering off a 150 mJ, 10 ps, 532 nm laser to generate 5 Multiplication-Sign 10{sup 10} photons/eV/s/Sr at 0.5 MeV with an overall bandwidth of less than 1%. The source will be able to produce photons up to energies of 2.5 MeV. We also discuss Compton scattering gamma-ray source predictions given by numerical codes.

Albert, F.; Anderson, S. G.; Ebbers, C. A.; Gibson, D. J.; Hartemann, F. V.; Marsh, R. A.; Messerly, M. J.; Prantil, M. A.; Wu, S.; Barty, C. P. J. [Lawrence Livermore National Laboratory, NIF and Photon Science, 7000 East avenue, Livermore, CA 94550 (United States)

2012-12-21

77

Experimental measurements of intensity distribution in two-photon compton scattering  

SciTech Connect

In two-photon Compton scattering, interaction of a gamma quantum with an atomic electron gives rise to emission of two degraded gamma quanta along with the recoil electron. An exact theory for this phenomenon has been provided by Mandl and Skyrme, and the expression for the cross section can be regarded as the two-photon Compton analog of the well-known Klein-Nishina relation for single-photon Compton scattering. The recent general interest in two-photon Compton scattering has been manyfold. First, it provides a test of quantum electrodynamics; secondly, it gives a mechanism of photon multiplication; and thirdly, there is an appreciable contribution of this effect to total scattering coefficients at higher incident photon energies.

Sandhu, B.S.; Singh, B.; Ghumman, B.S. (Punjabi Univ. (India))

1992-01-01

78

Compton Scattering in Ignited Thermonuclear Plasmas  

NASA Astrophysics Data System (ADS)

Inertially confined, ignited thermonuclear D-T plasmas will produce intense blackbody radiation at temperatures T?20keV; it is shown that the injection of GeV electrons into the burning core can efficiently generate high-energy Compton scattering photons. Moreover, the spectrum scattered in a small solid angle can be remarkably monochromatic, due to kinematic pileup; a peak brightness in excess of 1030photons/(mm2mrad2s0.1%bandwidth) is predicted. These results are discussed within the context of the Schwinger field and the Sunyaev-Zel’dovich effect.

Hartemann, F. V.; Siders, C. W.; Barty, C. P. J.

2008-03-01

79

Compton Scattering in Ignited Thermonuclear Plasmas  

NASA Astrophysics Data System (ADS)

Inertially confined, ignited thermonuclear D-T plasmas will produce intense blackbody radiation at temperatures T ˜ 20 keV; it is shown that the injection of GeV electrons into the burning core can efficiently generate high-energy Compton scattering photons. Moreover, the spectrum scattered in a small solid angle can be remarkably monochromatic, due to kinematic pileup; peak brightness in excess of 10^29 photons/(mm^2 x mrad^2 x s x 0.1% bandwidth) are predicted. Electron focusing of the ?-rays could produce electromagnetic fields exceeding the Schwinger critical field.

Hartemann, Frederic; Siders, Craig; Barty, Chris

2007-11-01

80

Precision 0.5 GW X-band rf system for advanced Compton scattering source  

Microsoft Academic Search

A Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering light source is being developed at LLNL. The electron beam for the Compton scattering interaction will be generated by a X-band RF gun and a X-band LINAC at the frequency of 11.424 GHz. High power RF in excess of 500 MW is needed to accelerate the electrons to energy of 250 MeV or greater

T. S. Chu; G. Anderson; D. Gibson; F. V. Hartemann; C. P. J. Barty; A. Vlieks; S. Tantawi; E. Jongewaard; S. G. Anderson

2009-01-01

81

Unitary constraints on Deeply Virtual Compton Scattering  

SciTech Connect

At moderately low momentum transfer ($-t$ up to 1 GeV$^2$) the coupling to the vector meson production channels gives the dominant contribution to real Compton and deeply virtual Compton scattering (DVCS). Starting from a Regge Pole approach that successfully describes vector meson production, the singular part of the corresponding box diagrams (where the intermediate vector meson-baryon pair propagates on-shell) is evaluated without any further assumptions (unitarity). Such a treatment explains not only the unexpectedly large DVCS unpolarized cross section that has been recently measured at Jefferson Laboratory (JLab), but also all the beam spin and charge asymmetries that has been measured at JLab and Hermes, without explicit need of Generalized Parton Distributions (GPD). The issue of the relationship between the two approaches is addressed.

J.M. Laget

2007-11-01

82

The Mathematical Foundations of 3D Compton Scatter Emission Imaging  

PubMed Central

The mathematical principles of tomographic imaging using detected (unscattered) X- or gamma-rays are based on the two-dimensional Radon transform and many of its variants. In this paper, we show that two new generalizations, called conical Radon transforms, are related to three-dimensional imaging processes based on detected Compton scattered radiation. The first class of conical Radon transform has been introduced recently to support imaging principles of collimated detector systems. The second class is new and is closely related to the Compton camera imaging principles and invertible under special conditions. As they are poised to play a major role in future designs of biomedical imaging systems, we present an account of their most important properties which may be relevant for active researchers in the field.

Truong, T. T.; Nguyen, M. K.; Zaidi, H.

2007-01-01

83

Deeply Virtual Compton Scattering at JLab Hall A  

SciTech Connect

The deeply virtual Compton scattering reaction has been investigated in the Hall A of the Jefferson Laboratory by measuring longitudinally polarized (e,e'gamma) cross sections, in the valence quark region, for protons and neutrons. In the proton channel, experimental results strongly support the factorization of the cross section at Q2 as low as 2 GeV2, opening the path to systematic measurements of generalized parton distributions (GPDs). In the neutron case, preliminary data show sensitivity to the angular momentum of quarks.

Eric Voutier

2007-04-16

84

Deeply virtual Compton scattering and nucleon structure  

SciTech Connect

Deeply Virtual Compton Scattering (DVCS) is the tool of choice to study Generalized Parton Distributions (GPD) in the nucleon. After a general introduction to the subject, a review of experimental results from various facilities is given. Following the first encouraging results, new generation dedicated experiments now allow unprecedented precision and kinematical coverage. Several new results were presented during the conference, showing significant progress in this relatively new field. Prospects for future experiments are presented. The path for the experimental determination of GPDs appears now open.

M. Garcon

2006-11-01

85

Deeply Virtual Compton Scattering off the Neutron  

NASA Astrophysics Data System (ADS)

The present experiment exploits the interference between the deeply virtual Compton scattering (DVCS) and the Bethe-Heitler processes to extract the imaginary part of DVCS amplitudes on the neutron and on the deuteron from the helicity-dependent D(e?,e'?)X cross section measured at Q2=1.9GeV2 and xB=0.36. We extract a linear combination of generalized parton distributions (GPDs) particularly sensitive to Eq, the least constrained GPD. A model dependent constraint on the contribution of the up and down quarks to the nucleon spin is deduced.

Mazouz, M.; Camsonne, A.; Camacho, C. Muñoz; Ferdi, C.; Gavalian, G.; Kuchina, E.; Amarian, M.; Aniol, K. A.; Beaumel, M.; Benaoum, H.; Bertin, P.; Brossard, M.; Chen, J.-P.; Chudakov, E.; Craver, B.; Cusanno, F.; de Jager, C. W.; Deur, A.; Feuerbach, R.; Fieschi, J.-M.; Frullani, S.; Garçon, M.; Garibaldi, F.; Gayou, O.; Gilman, R.; Gomez, J.; Gueye, P.; Guichon, P. A. M.; Guillon, B.; Hansen, O.; Hayes, D.; Higinbotham, D.; Holmstrom, T.; Hyde, C. E.; Ibrahim, H.; Igarashi, R.; Jiang, X.; Jo, H. S.; Kaufman, L. J.; Kelleher, A.; Kolarkar, A.; Kumbartzki, G.; Laveissiere, G.; Lerose, J. J.; Lindgren, R.; Liyanage, N.; Lu, H.-J.; Margaziotis, D. J.; Meziani, Z.-E.; McCormick, K.; Michaels, R.; Michel, B.; Moffit, B.; Monaghan, P.; Nanda, S.; Nelyubin, V.; Potokar, M.; Qiang, Y.; Ransome, R. D.; Réal, J.-S.; Reitz, B.; Roblin, Y.; Roche, J.; Sabatié, F.; Saha, A.; Sirca, S.; Slifer, K.; Solvignon, P.; Subedi, R.; Sulkosky, V.; Ulmer, P. E.; Voutier, E.; Wang, K.; Weinstein, L. B.; Wojtsekhowski, B.; Zheng, X.; Zhu, L.

2007-12-01

86

Status of the Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

The Compton Gamma Ray Observatory and three of its four experiment packages continue to function in a nearly flawless manner now well into the eighth year of mission operations. Only the EGRET instrument is operating with reduced capability due mainly to the depleted spark-chamber gas, but it is nonetheless still expected to make significant contributions, notably in the area of Solar flares and AGN variability. We discuss the status of the mission as of mid-1999 as well as the prospects of an extended mission lasting well into the first decade of the next century. .

Gehrels, Neil; Shrader, Chris

2000-04-01

87

Laser Compton scattering for a linearly polarized laser  

NASA Astrophysics Data System (ADS)

Laser Compton light sources are potential candidates for the next generation of high-brightness X or ?-ray sources. When increasing the laser power to obtain intense X-ray laser, nonlinear Compton scattering happens. Nonlinear Compton scattering of linearly polarized laser beam is discussed in this paper. A complete transition probability formula is introduced and the polarization properties of final photons are discussed for different conditions.

Li, Dong-Guo

2011-04-01

88

Advanced Gamma-Ray Detection Concepts Combined with Real-Time Compton Suppression for Nondestructive, Gamma-Ray Characterization of Remote Handled Waste  

SciTech Connect

Nondestructive gamma ray characterization of remote-handled waste is significantly complicated by the presence of Compton scattering in the detector and waste matrix produced by intense cesium gamma rays. This research seeks to understand the photophysics of a new type of inorganic scintillation gamma ray detector, optimize the combination of this gamma ray detector with a Compton guard detector, develop new Monte Carlo solution algorithms for modeling Compton scattering in the waste, and to model the real time intensity of cesium produced Compton scattering. A successful research program will provide the fundamental information needed to design and develop advanced Compton spectrometers for assay of remote handled waste and new higher sensitivity spectrometers for environmental measurements.

Mcllwain, Michael E.; Haghighat, Alireza; Dorenbos, Pieter; Hartwell, John K.

2005-06-01

89

Timelike Virtual Compton Scattering from Electron-Positron Radiative Annihilation  

SciTech Connect

We propose measurements of the deeply virtual Compton amplitude (DVCS), gamma* to H H-bar gamma, in the timelike t = (p_{H} + p_{H-bar})^2 > 0 kinematic domain which is accessible at electron-positron colliders via the radiative annihilation process e+ e- to H H-bar gamma. These processes allow the measurement of timelike deeply virtual Compton scattering for a variety of H H-bar hadron pairs such as pi+ pi-, K+ K-, and D D-bar as well as p p-bar. As in the conventional spacelike DVCS, there are interfering coherent amplitudes contributing to the timelike processes involving C= - form factors. The interference between the amplitudes measures the phase of the C=+ timelike DVCS amplitude relative to the phase of the timelike form factors and can be isolated by considering the forward-backward e+ \\leftrightarrow e- asymmetry. The J=0 fixed pole contribution which arises from the local coupling of the two photons to the quark current plays a special role. As an example we present a simple

Afanaciev, Andrei; Afanasev, Andrei; Afanaciev, Andrei; Afanasev, Andrei; J. Brodsky, Stanley; E. Carlson, Carl; Mukherjee, Asmita

2009-01-01

90

Timelike Virtual Compton Scattering from Electron-Positron Radiative Annihilation  

SciTech Connect

We propose measurements of the deeply virtual Compton amplitude (DVCS) {gamma}* {yields} H{bar H}{gamma} in the timelike t = (p{sub H} + p{sub {bar H}}){sup 2} > 0 kinematic domain which is accessible at electron-positron colliders via the radiative annihilation process e{sup +}e{sup -} {yields} H{bar H}{gamma}. These processes allow the measurement of timelike deeply virtual Compton scattering for a variety of H{bar H} hadron pairs such as {pi}{sup +}{pi}{sup -}, K{sup +}K{sup -}, and D{bar D} as well as p{bar p}. As in the conventional spacelike DVCS, there are interfering coherent amplitudes contributing to the timelike processes involving C = - form factors. The interference between the amplitudes measures the phase of the C = + timelike DVCS amplitude relative to the phase of the timelike form factors and can be isolated by considering the forward-backward e{sup +} {leftrightarrow} e{sup -} asymmetry. The J = 0 fixed pole contribution which arises from the local coupling of the two photons to the quark current plays a special role. As an example we present a simple model.

Afanasev, Andrei; /Hampton U. /Jefferson Lab; Brodsky, Stanley J.; /SLAC; Carlson, Carl E.; /William-Mary Coll.; Mukherjee, Asmita; /Indian Inst. Tech., Mumbai

2009-03-31

91

Timelike virtual compton scattering from electron-positron radiative annihilation  

SciTech Connect

We propose measurements of the deeply virtual Compton amplitude (DVCS) {gamma}*{yields}hh{gamma} in the timelike t=(p{sub h}+p{sub h}){sup 2}>0 kinematic domain which is accessible at electron-positron colliders via the radiative annihilation process e{sup +}e{sup -{yields}}hh{gamma}. These processes allow the measurement of timelike deeply virtual Compton scattering for a variety of hh hadron pairs such as {pi}{sup +{pi}-}, K{sup +}K{sup -}, and DD as well as pp. As in the conventional spacelike DVCS, there are interfering coherent amplitudes contributing to the timelike processes involving C=- form factors. The interference between the amplitudes measures the phase of the C=+ timelike DVCS amplitude relative to the phase of the timelike form factors and can be isolated by considering the forward-backward e{sup +{r_reversible}}e{sup -} asymmetry. The J=0 fixed pole contribution which arises from the local coupling of the two photons to the quark current plays a special role. As an example we present a simple model.

Afanasev, Andrei [Department of Physics, Hampton University, Hampton, Virginia 23668, USA, and Theory Center, Thomas Jefferson National Accelerator Facility, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Brodsky, Stanley J. [SLAC National Accelerator Laboratory, Stanford University, Stanford, California 94309 (United States); Carlson, Carl E. [Department of Physics, College of William and Mary, Williamsburg, Virginia 23187 (United States); Mukherjee, Asmita [Department of Physics, Indian Institute of Technology, Powai, Mumbai 400076 (India)

2010-02-01

92

Energy measurement of electron beams by Compton scattering  

NASA Technical Reports Server (NTRS)

A method has been proposed to utilize the well-known Compton scattering process as a tool to measure the centroid energy of a high energy electron beam at the 0.01% level. It is suggested to use the Compton scattering of an infrared laser off the electron beam, and then to measure the energy of the scattered gamma-rays very precisely using solid-state detectors. The technique proposed is applicable for electron beams with energies from 200 MeV to 16 GeV using presently available lasers. This technique was judged to be the most viable of all those proposed for beam energy measurements at the nearby Continuous Electron Beam Accelerator Facility (CEBAF). Plans for a prototype test of the technique are underway, where the main issues are the possible photon backgrounds associated with an electron accelerator and the electron and laser beam stabilities and diagnostics. The bulk of my ASEE summer research has been spent utilizing the expertise of the staff at the Aerospace Electronics Systems Division at LaRC to assist in the design of the test. Investigations were made regarding window and mirror transmission and radiation damage issues, remote movement of elements in ultra-high vacuum conditions, etc. The prototype test of the proposed laser backscattering method is planned for this December.

Keppel, Cynthia

1995-01-01

93

Kapteyn series in high intensity Compton scattering  

NASA Astrophysics Data System (ADS)

In discussing the signatures available from high intensity Compton scattering, a problem of considerable interest in photon scattering from active galactic nuclei and their emission jets, Harvey et al (2009 Phys. Rev. A 79 063407) showed that the properties of some other than conventional Kapteyn series play fundamental roles in determining the spectral output both with respect to frequency and with respect to emission angle. While they were able to provide bounds to the required series in terms of known Kapteyn series that could be summed analytically in closed form, only numerical analysis could take their investigation further as they demonstrated. The purpose of this paper is to show that the many Kapteyn series involved in the scattering problem can all be reduced either to analytic form or to a single Kapteyn series that cannot be evaluated in closed form but for which an integral representation is available. This reduction is of considerable benefit in controlling the correctness and accuracy of numerical investigations; the reduction also provides significant insight into some basic procedures for summing such unconventional Kapteyn series as well as allowing a better understanding of the dependence of the scattering on the physical parameters involved than would be the case directly from the series.

Lerche, I.; Tautz, R. C.

2010-03-01

94

Development of a Compton Scattering Beam Flux Monitor for HIGS  

NASA Astrophysics Data System (ADS)

A beam flux monitor is being developed for use with the high-intensity polarized gamma-ray beam at the TUNL/DFELL (Duke Free Electron Laser Laboratory) High Intensity Gamma-Ray Source (HIGS). At the higher beam intensities and energies which will soon become available, new methods for beam flux measurements are required. One such method is the use of a NaI detector at a small angle relative to the beam axis, which detects the photons that are Compton-scattered from a thin Pb target located downstream from any other experimental apparatus. This method allows monitoring of the beam flux in parallel with experimental data acquisition. The feasibility and accuracy of this method at relevant energies will be discussed. Work partially supported by DOE Grant Nos. DE-FG02-97ER41033, 41042, and 41046, and NSF Grant No. PHY-0075078.

Keeter, K. J.; Sabourov, A. L.; Nesaraja, C. D.; Sabourov, K.; Weller, H. R.; Prior, R. M.; Spraker, M.

2000-10-01

95

Compton coincidence volumetric imaging: a new x-ray volumetric imaging modality based on Compton scattering  

NASA Astrophysics Data System (ADS)

Compton scattering is a dominant interaction during radiography and computed tomography x-ray imaging. However, the scattered photons are not used for extracting imaging information, but seriously degrade image quality. Here we introduce a new scheme that overcomes most of the problems associated with existing Compton scattering imaging schemes and allows Compton scattered photons to be effectively used for imaging. In our scheme, referred as Compton coincidence volumetric imaging (CCVI), a collimated monoenergetic x-ray beam is directed onto a thin semiconductor detector. A small portion of the photons is Compton scattered by the detector and their energy loss is detected. Some of the scattered photons intersect the imaging object, where they are Compton scattered a second time. The finally scattered photons are recorded by an areal energy resolving detector panel around the object. The two detectors work in coincidence mode. CCVI images the spatial electron density distribution in the imaging object. Similar to PET imaging, the event location can be located within a curve; therefore the imaging reconstruction algorithms are also similar to those of PET. Two statistical iterative imaging reconstruction algorithms are tested. Our study verifies the feasibility of CCVI in imaging acquisition and reconstruction. Various aspects of CCVI are discussed. If successfully implemented, it will offer a great potential for imaging dose reduction compared with x-ray CT. Furthermore, a CCVI modality will have no moving parts, which potentially offers cost reduction and faster imaging speed.

Xu, Xiaochao

2014-03-01

96

Compton scattering vertex for massive scalar QED  

SciTech Connect

We investigate the Compton scattering vertex of charged scalars and photons in scalar quantum electrodynamics (SQED). We carry out its nonperturbative construction consistent with Ward-Fradkin-Green-Takahashi identity which relates 3-point vertices to the 4-point ones. There is an undetermined part which is transverse to one or both the external photons, and needs to be evaluated through perturbation theory. We present in detail how the transverse part at the 1-loop order can be evaluated for completely general kinematics of momenta involved in covariant gauges and dimensions. This involves the calculation of genuine 4-point functions with three massive propagators, the most nontrivial integrals reported in this paper. We also discuss possible applications of our results.

Bashir, A.; Concha-Sanchez, Y. [Instituto de Fisica y Matematicas, Universidad Michoacana de San Nicolas de Hidalgo, Apartado Postal 2-82, Morelia, Michoacan 58040 (Mexico); Delbourgo, R. [School of Mathematics and Physics, University of Tasmania, Private Bag 37 GPO, Hobart 7001 (Australia); Tejeda-Yeomans, M. E. [Departamento de Fisica, Universidad de Sonora, Apartado Postal 1626, Hermosillo, Sonora 83000 (Mexico)

2009-08-15

97

Electron distributions in nonlinear Compton scattering  

NASA Astrophysics Data System (ADS)

Based on quantum theory, we investigate the distribution of the electrons scattered in the nonlinear Compton effect by an electromagnetic plane wave. The monochromatic case, examined in detail, reveals features of the electron distribution that are useful in the understanding of the pulsed plane-wave case for particular intensity and electron energy regimes. The graphs displayed focus on the case of a head-on or nearly head-on collision of an energetic electron with an electromagnetic circularly polarized pulsed plane wave and show that the deviation in direction is extremely small, while the distribution in energy can be visibly different from that of the initial electron. Two pulse shapes, several laser intensities, and high incident electron energies are considered.

Boca, Madalina; Dinu, Victor; Florescu, Viorica

2012-07-01

98

High-energy Picosecond Laser Pulse Recirculation for Compton Scattering  

SciTech Connect

Frequency upconversion of laser-generated photons by inverse Compton scattering for applications such as nuclear spectroscopy and gamma-gamma collider concepts on the future ILC would benefit from an increase of average source brightness. The primary obstacle to higher average brightness is the relatively small Thomson scattering cross section. It has been proposed that this limitation can be partially overcome by use of laser pulse recirculation. The traditional approach to laser recirculation entails resonant coupling of low-energy pulse train to a cavity through a partially reflective mirror. Here we present an alternative, passive approach that is akin to 'burst-mode' operation and does not require interferometric alignment accuracy. Injection of a short and energetic laser pulse is achieved by placing a thin frequency converter, such as a nonlinear optical crystal, into the cavity in the path of the incident laser pulse. This method leads to the increase of x-ray/gamma-ray energy proportional to the increase in photon energy in frequency conversion. Furthermore, frequency tunability can be achieved by utilizing parametric amplifier in place of the frequency converter.

Jovanovic, I; Anderson, S G; Betts, S M; Brown, C; Gibson, D J; Hartemann, F V; Hernandez, J E; Johnson, M; McNabb, D P; Messerly, M; Pruet, J; Shverdin, M Y; Siders, C W; Tremaine, A M; Barty, C J

2007-06-12

99

Comptonization of gamma rays by cold electrons  

NASA Technical Reports Server (NTRS)

An analytic method is developed for calculating the emergent spectrum of gamma-rays and X-rays scattered in a homogeneous medium with low-temperature electrons. The Klein-Nishina corrections of the scattering cross section and absorption processes are taken in account. The wavelength relaxation and the spatial diffusion problems are solved separately, and the emergent spectrum is calculated by convolving the evolution function of the spectrum in an infinite medium with the photon luminosity resulting from the spatial diffusion in a finite sphere. The analytic results are compared with that of Monte Carlo calculations and it is concluded that the analytic result is quite accurate.

Xu, Yueming; Ross, Randy R.; Mccray, Richard

1991-01-01

100

Model Independent Dispersion Approach to Proton Compton Scattering.  

National Technical Information Service (NTIS)

The proton Compton scattering at low and intermediate energies is studied by means of a dispersion framework which exploits in an optimal way the (fixed momentum transfer) analyticity properties of the amplitudes in conjunction with the consequences of th...

I. Caprini I. Guiasu E. E. Radescu

1980-01-01

101

Investigating Neutron Polarizabilities through Compton Scattering on Light Nuclei  

NASA Astrophysics Data System (ADS)

This talk will focus on elastic Compton scattering on He-3 as an instrument to extract the neutron polarizabilities. The calculations for this process have been performed for photon energies comparable to the pion mass within the framework of Chiral effective field theory. The results show that these computations, when used in concert with future data from HIGS and results from elastic deuteron Compton scattering, should give significant new information about the neutron polarizabilities.

Shukla, Deepshikha

2008-04-01

102

Study of Laser Compton Scattering in a Plasma Channel  

NASA Astrophysics Data System (ADS)

Compton scattering of laser and electron beams in a plasma channel can be utilized for high intensity X-ray source and polarized positron source for future linear colliders. Transportation of a CO2 laser beam by a 17mm plasma channel was observed. An X-ray generation experiment via laser Compton scattering in the plasma channel was attempted but the signal could not be separated from the background because of the electron beam modulation by the plasma.

Kumita, T.; Kamiya, Y.; Ben-Zvi, I.; Kusche, K.; Pogorelsky, I. V.; Yakimenko, V.; Siddons, D. P.; Hirose, T.; Kashiwagi, S.; Washio, M.; Cline, D.; Zhou, F.; Kaganovich, D.; Zigler, A.

2004-10-01

103

Measurement of Compton scattering in phantoms by germanium detector  

Microsoft Academic Search

Quantitative Anger camera tomography requires correction for Compton scattering. The Anger camera spectral-fitting technique can measure scatter fractions at designated positions in an image, allowing for correction. To permit verification of those measurements for 131I, scatter fractions were determined with a high-purity germanium (HPGe) detector and various phantom configurations. The scatter fraction values for 99mTc were also measured and are

K. R. Zasadny; K. F. Koral; R. J. Jaszczak

1990-01-01

104

Recent Results from the Compton Gamma Ray Observatory  

Microsoft Academic Search

A selection of recent scientific findings from the Compton Gamma Ray Observatory is presented. In gamma-ray burst astrophysics, notable is the dramatic confirmation that bursts are isotropic but spatially inhomogeneous in their distribution. They exhibit temporal effects consistent with a time dilation as expected for a cosmologically distributed population, however alternate explanations cannt be ruled out. Also notable is the

C. R. Shrader; N. Gehrels

1995-01-01

105

Nucleon Polarizabilities from Low-Energy Compton Scattering  

Microsoft Academic Search

Effective field theory (EFT) is used to give a model-independent description of Compton scattering from both the proton and the deuteron at energies comparable to the pion mass. For the proton, we use chiral perturbation theory [1]; for the deuteron, the recently developed EFT for two nucleons [2]. The scattering amplitudes, calculated to fourth order in small momenta, contain four

Judith A. McGovern

2003-01-01

106

Multiple synchrotron self-Compton modeling of gamma-ray flares in 3C 279  

NASA Astrophysics Data System (ADS)

The correlation often observed in blazars between optical-to-radio outbursts and gamma-ray flares suggests that the high-energy emission region shall be co-spatial with the radio knots, several parsecs away from the central engine. This would prevent the important contribution at high-energies from the Compton scattering of seed photons from the accretion disk and the broad-line region that is generally used to model the spectral energy distribution of low-frequency peaking blazars. While a pure synchrotron self-Compton model has so far failed to explain the observed gamma-ray emission of a flat spectrum radio quasar like 3C 279, the inclusion of the effect of multiple inverse-Compton scattering might solve the apparent paradox. Here, we present for the first time a physical, self-consistent SSC modeling of a series of shock-waves in the jet of 3C 279. We show that the analytic description of the high-energy emission from multiple inverse-Compton scatterings in the Klein-Nishina limit can fairly well account for the observed gamma-ray spectrum of 3C 279 in flaring states.

Türler, Marc; Björnsson, Claes-Ingvar

2012-03-01

107

The early detection of osteoporosis by Compton gamma ray spectroscopy  

Microsoft Academic Search

The density of the distal end of the radius is one of the parameters used to determine the presence and degree of osteoporosis in patients. The bone density has been determined by measuring the intensity of Compton scattered photons, since this is proportional to the absolute density of the scatterer, in materials for which Z\\/A is constant. A collimated beam

G. Hazan; I. Leichter; E. Loewinger; A. Weinreb; G. C. Robin

1977-01-01

108

Low-Intensity Nonlinear Spectral Effects in Compton Scattering  

NASA Astrophysics Data System (ADS)

Nonlinear effects are known to occur in Compton scattering light sources, when the laser normalized potential A approaches unity. In this Letter, it is shown that nonlinear spectral features can appear at arbitrarily low values of A, if the fractional bandwidth of the laser pulse ??-1 is sufficiently small to satisfy A2???1. A three-dimensional analysis, based on a local plane wave, slow-varying envelope approximation, enables the study of these effects for realistic interactions between an electron beam and a laser pulse, and their influence on high-precision Compton scattering light sources.

Hartemann, Frederic V.; Albert, Félicie; Siders, Craig W.; Barty, C. P. J.

2010-09-01

109

Coded-aperture Compton camera for gamma-ray imaging  

NASA Astrophysics Data System (ADS)

This dissertation describes the development of a novel gamma-ray imaging system concept and presents results from Monte Carlo simulations of the new design. Current designs for large field-of-view gamma cameras suitable for homeland security applications implement either a coded aperture or a Compton scattering geometry to image a gamma-ray source. Both of these systems require large, expensive position-sensitive detectors in order to work effectively. By combining characteristics of both of these systems, a new design can be implemented that does not require such expensive detectors and that can be scaled down to a portable size. This new system has significant promise in homeland security, astronomy, botany and other fields, while future iterations may prove useful in medical imaging, other biological sciences and other areas, such as non-destructive testing. A proof-of-principle study of the new gamma-ray imaging system has been performed by Monte Carlo simulation. Various reconstruction methods have been explored and compared. General-Purpose Graphics-Processor-Unit (GPGPU) computation has also been incorporated. The resulting code is a primary design tool for exploring variables such as detector spacing, material selection and thickness and pixel geometry. The advancement of the system from a simple 1-dimensional simulation to a full 3-dimensional model is described. Methods of image reconstruction are discussed and results of simulations consisting of both a 4 x 4 and a 16 x 16 object space mesh have been presented. A discussion of the limitations and potential areas of further study is also presented.

Farber, Aaron M.

110

Generation of laser Compton gamma-rays in the SAGA light source storage ring  

NASA Astrophysics Data System (ADS)

A medium-scale synchrotron light source of GeV-class equipped with an infrared high-power laser can generate stable high-flux gamma-rays at several MeV via laser Compton scattering. We constructed an experimental setup for high-flux gamma-ray generation in the SAGA light source storage ring. A head-on collision between a 1.4 GeV electron beam and laser photons with a 10.6 ?m wavelength produced gamma-rays up to a maximum energy of 3.5 MeV. Since the laser Compton scattering does not influence the beam quality, these gamma-rays can be generated in conjunction with user time for synchrotron radiation research. The event rate was designed to be 1.4×108 s-1 with a beam current of 300 mA and a laser power of 10 W. As a first step in high-flux gamma-ray generation, we performed beam tests at a low beam current to evaluate the characteristics of the gamma-rays. Gamma-ray generation with no reduction in beam lifetime was confirmed by these tests. The experimental results show that the effective gamma-ray flux was almost 40% of the design value. The laser Compton gamma-ray was also applied to measure the machine parameters of the storage ring. The beam energy was successfully determined with relative uncertainties on the order of 10 -3 by analyzing the gamma-ray spectrum for the stored beam, which ranged in energy from 0.6 to 1.4 GeV.

Kaneyasu, T.; Takabayashi, Y.; Iwasaki, Y.; Koda, S.

2011-12-01

111

Probing the Fermi surface by positron annihilation and Compton scattering  

NASA Astrophysics Data System (ADS)

Positron annihilation and Compton scattering are important probes of the Fermi surface. Relying on conservation of energy and momentum, being bulk sensitive and not limited by short electronic mean-free-paths, they can provide unique information in circumstances when other methods fail. Using a variety of examples, their contribution to knowledge about the electronic structure of a wide range of materials is demonstrated.

Dugdale, S. B.

2014-04-01

112

Measurements of Compton scattered transition radiation at high Lorentz factors  

NASA Astrophysics Data System (ADS)

X-ray transition radiation can be used to measure the Lorentz factor of relativistic particles. Standard transition radiation detectors (TRDs) typically incorporate thin plastic foil, foam, or fiber radiators and gas-filled X-ray detectors, and are sensitive up to ?˜10 4. To reach Lorentz factors up to ?˜10 5, thicker, denser radiators can be used, which consequently produce X-rays of harder energies (?100 keV) . At these energies, scintillator detectors are more efficient in detecting the hard X-rays, and Compton scattering of the X-rays out of the path of the particle becomes important. The Compton scattering can be utilized to separate the transition radiation from the ionization background spatially. The use of conducting metal foils is predicted to yield enhanced signals compared to standard nonconducting plastic foils of the same dimensions. We have designed and built an inorganic scintillator-based Compton Scatter TRD optimized for high Lorentz factors and exposed it to high-energy electrons at the CERN SPS. We present the results of the accelerator tests and comparisons to simulations, demonstrating (1) the effectiveness of the Compton Scatter TRD approach; (2) the performance of conducting aluminum foils; and (3) the ability of a TRD to measure energies approximately an order of magnitude higher than previously used in very high-energy cosmic ray studies.

Case, Gary L.; Altice, P. Parker; Cherry, Michael L.; Isbert, Joachim; Patterson, Donald; Mitchell, John W.

2004-05-01

113

Pomeranchuk Exchange and Low-Energy Theorems in Compton Scattering  

Microsoft Academic Search

The method, introduced in a previous work, of deriving the kinematical properties of zero-mass bosons from the limit of a theory with massive particles is here applied to the problem of Compton scattering. It is shown that the same mechanism that eliminates the factor of alphapi(t) from the nonsense amplitude in pion photoproduction processes and allows the pion pole to

Farzam Arbab; Richard C. Brower

1969-01-01

114

Unification of synchrotron radiation and inverse Compton scattering  

SciTech Connect

This article describes a new approach to radiation theory. This theory, expounded by Lieu and Axford, uses the concept of inverse Compton scattering to explain with unprecedented simplicity all the classical and quantum electrodynamic properties of synchrotron radiation, unifying two fundamental processes in physics. Ramifications of this theory are also discussed. 13 refs., 1 fig.

Lewin, W.H.G. [Massachusetts Institute of Technology, Cambridge, MA (United States); Barber, D.P. [Deutsches Elektronen Synchrotron, Hamburg (Germany); Chen, P. [Stanford Univ., Stanford, CA (United States)

1995-03-24

115

Design and evaluation of gamma imaging systems of Compton and hybrid cameras  

NASA Astrophysics Data System (ADS)

Systems for imaging and spectroscopy of gamma-ray emission have been widely applied in environment and medicine applications. The superior performance of LaBr3:Ce detectors established them as excellent candidates for imaging and spectroscopy of gamma-rays. In this work, Compton cameras and hybrid cameras with a two-plane array of LaBr3:Ce detectors, one for the scattering and one for the absorbing detector arrays were designed and investigated. The feasibility of using LaBr3 in Compton cameras was evaluated with a bench top experiment in which two LaBr3:Ce detectors were arranged to mimic a Compton camera with one scattering and eight absorbing detectors. In the hybrid system the combination of the imaging methods of Compton and coded aperture cameras enables the system to cover the energy range of approximately 100 keV to a few MeV with good efficiency and angular resolution. The imaging performance of the hybrid imaging system was evaluated via Monte Carlo simulations. The image reconstruction algorithms of direct back-projections were applied for instant or real time imaging applications; this imaging system is capable of achieving an angular resolution of approximately 0.3 radians (17°). With image reconstruction algorithms of Expectation Maximized Likelihood, the image quality was improved to approximately 0.1 radians (or 6°). For medical applications in proton therapy, a Compton camera system to image the gamma-ray emission during treatment was designed and investigated. Gamma rays and X-rays emitted during treatment illustrate the energy deposition along the path of the proton beams and provide an opportunity for online dose verification. This Compton camera is designed to be capable of imaging gamma rays in 3D and is one of the candidates for imaging gamma emission during the treatment of proton therapy beside of the approach of positron emission tomography. In order to meet the requirement for spatial resolution of approximately 5 mm or less to meaningfully verify the dose via imaging gamma rays of 511 keV to 2 MeV, position sensing techniques with pixilated LaBr3 (Ce) crystal were applied in each detector. The pixilated LaBr3 (Ce) crystal was used in both the scattering and absorbing detectors. Image reconstruction algorithms of OS-EML were applied to obtain 3D images.

Feng, Yuxin

116

Magnetic Compton-induced pair cascade model for gamma-ray pulsars  

Microsoft Academic Search

Electrons accelerated to relativistic energies in pulsar magnetospheres will Compton scatter surface thermal emission and nonthermal optical, UV, and soft X-ray emission to gamma-ray energies, thereby initiating a pair cascade through synchrotron radiation and magnetic pair production. This process is proposed as the origin of the high-energy radiation that has been detected from six isolated pulsars. We construct an analytic

Steven J. Sturner; Charles D. Dermer; F. Curtis Michel

1995-01-01

117

Directional gamma sensing from covariance processing of inter-detector Compton crosstalk energy asymmetries  

NASA Astrophysics Data System (ADS)

Energy asymmetry of inter-detector crosstalk from Compton scattering can be exploited to infer the direction to a gamma source. A covariance approach extracts the correlated crosstalk from data streams to estimate matched signals from Compton gammas split over two detectors. On a covariance map the signal appears as an asymmetric cross diagonal band with axes intercepts at the full photo-peak energy of the original gamma. The asymmetry of the crosstalk band can be processed to determine the direction to the radiation source. The technique does not require detector shadowing, masking, or coded apertures, thus sensitivity is not sacrificed to obtain the directional information. An angular precision of better than 1° of arc is possible, and processing of data streams can be done in real time with very modest computing hardware.

Trainham, R.; Tinsley, J.

2014-06-01

118

Compton scattering: From deeply virtual to quasi-real  

NASA Astrophysics Data System (ADS)

We address the question of interpolation of the virtual Compton scattering process off a polarized nucleon target between the deeply virtual regime for the initial-state photon and its near on-shell kinematics making use of the photon helicity-dependent Compton Form Factors (CFFs) as a main ingredient of the formalism. The five-fold differential cross section1 for the reaction with all possible polarization options for the lepton and nucleon spins is evaluated in terms of CFFs in the rest reference frame of the initial-state nucleon. We suggest a rather simple parametrization of the Compton hadronic tensor in terms of CFFs which are free from kinematical singularities and are directly related, at large photon virtualities, to generalized parton distributions. We also provide a relation of our basis spanned by a minimal number of Dirac bilinears to the one introduced by Tarrach for the parametrization of the virtual Compton tensor and utilize the former to establish a set of equalities among our CFFs and generalized polarizabilities. As a complementary result, we express Compton scattering in the Born approximation in terms of CFFs as well.

Belitsky, A. V.; Müller, D.; Ji, Y.

2014-01-01

119

Inverse Compton Scattering from Laser Accelerated Quasi-Monoenergetic Electrons  

NASA Astrophysics Data System (ADS)

The progress of the laser accelerator shows us the possible applications to the industries, such as an inspection source for soft materials like as human bodies, plants foods and medicines. The inverse Compton scattering will realize such a novel inspection system. We demonstrate for the fist time that the laser-accelerated mono-energetic electrons inversely scatter the same counter laser beam to the Compton X-ray emissions. A Ti:sapphire laser (500mJ width 150fs) is divided into two beams. Main beam is focused to an edge of a helium gasjet to accelerate electrons to 13 and 22 MeV monoenergies, which inversely scattered the counter laser beam into 6 and 11 keV X-ray emissions in agreement with that calculated from the obtained electron spectra. The scattering is within 30 deg. around the main beam direction.

Mori, Yoshitaka; Kuwabara, Hajime; Ishii, Katsuhiro; Hanayama, Ryohei; Kawashima, Toshiyuki; Kitagawa, Yoneyoshi

2010-11-01

120

Laser Design for Next Generation Compton Scattering Source at LLNL  

NASA Astrophysics Data System (ADS)

We describe laser systems designed for the next generation Mono-Energetic Gamma-Ray (MEGa-ray) Compton scattering light source at LLNL. An 80 fs Yb:doped fiber oscillator seeds a photogun drive laser (PDL) and a high energy interaction system laser (ILS). Utilizing chirped pulse amplification (CPA) in fiber, the PDL will generate 80 ?J, spatially and temporally shaped pulses at 263 nm at 120 Hz precisely synchronized to the linac RF. The PDL system employs large mode photonic bandgap fibers and large area multi-layer dielectric gratings to generate over 1mJ per pulse with high recompression fidelity prior to frequency quadrupling. The high energy, 120 W ILS utilizes (CPA) in Nd:YAG to amplify a sub-nanometer bandwidth 20 ?J pulses from a fiber system to 1 J. A novel pulse stretcher provides a dispersion of over 7000 ps/nm to expand a several picosecond wide seed pulse to 6 ns. After amplification, the pulse is recompressed to 10 ps with a hyper-dispersive pulse compressor. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Shverdin, Miro; Albert, Felicie; Anderson, Scott; Bayramian, Andy; Betts, Shawn; Cross, Rick; Ebbers, Chris; Gibson, David; Marsh, Roark; Messerly, Michael; Hartemann, Fred; Scarpetti, Ray; Siders, Craig; Barty, Chris

2010-11-01

121

Compton scattering of Fe K? lines in magnetic cataclysmic variables  

NASA Astrophysics Data System (ADS)

Compton scattering of X-rays in the bulk flow of the accretion column in magnetic cataclysmic variables (mCVs) can significantly shift photon energies. We present Monte Carlo simulations based on a non-linear algorithm demonstrating the effects of Compton scattering on the H-, He-like and neutral Fe K? lines produced in the post-shock region of the accretion column. The peak line emissivities of the photons in the post-shock flow are taken into consideration and frequency shifts due to Doppler effects are also included. We find that line profiles are most distorted by Compton scattering effects in strongly magnetized mCVs with a low white dwarf mass and high mass accretion rate and which are viewed at an oblique angle with respect to the accretion column. The resulting line profiles are most sensitive to the inclination angle. We have also explored the effects of modifying the accretion column width and using a realistic emissivity profile. We find that these do not have a significant overall effect on the resulting line profiles. A comparison of our simulated line spectra with high-resolution Chandra/HETGS observations of the mCV GK Per indicates that a wing feature redward of the 6.4-keV line may result from Compton recoil near the base of the accretion column.

McNamara, A. L.; Kuncic, Z.; Wu, K.; Galloway, D. K.; Cullen, J. G.

2008-01-01

122

Implementation of the Doppler broadening of a Compton-scattered photon into the EGS4 code  

Microsoft Academic Search

A modification to the general-purpose Monte Carlo electron-photon transport code EGS4 [1] was made in order to include Doppler broadening of Compton-scattered photon energy due to electron pre-collision motion. The Compton-scattered photon energy is sampled from a cross section formula based on the Compton profile, and the Compton scattering is sustained if the energy imparted to the electron is less

Y. Namito; S. Ban; H. Hirayama

1994-01-01

123

Is Compton scattering in magnetic fields really infrared divergent  

SciTech Connect

The infrared behavior of QED changes drastically in the presence of a strong magnetic field: the electron self-energy and the vertex function are infrared [ital finite], in contrast with field-free QED, while new infrared divergences appear that are absent in free space. One famous example of the latter is the infrared catastrophe of magnetic Compton scattering, where the cross section for scattering of photons from electrons which undergo a transition to the Landau ground state [ital diverges] as the frequency of the incoming photon goes to zero. We examine this divergence in more detail and prove that the singularity of the cross section is [ital removed] as soon as proper account is taken of all quantum electrodynamical processes that become indistinguishable from Compton scattering in the limit of vanishing frequency of the incident photon.

Kachelriess, M.; Berg, D.; Wunner, G. (Theoretische Physik I, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany))

1995-01-15

124

GAMMA-RAY COMPTON LIGHT SOURCE DEVELOPMENT AT LLNL  

SciTech Connect

A new class of tunable, monochromatic {gamma}-ray sources capable of operating at high peak and average brightness is currently being developed at LLNL for nuclear photoscience and applications. These novel systems are based on Compton scattering of laser photons by a high brightness relativistic electron beam produced by an rf photoinjector. A prototype, capable of producing > 10{sup 8} 0.7 MeV photons in a single shot, with a fractional bandwidth of 1%, and a repetition rate of 10 Hz, is currently under construction at LLNL; this system will be used to perform nuclear resonance fluorescence experiments. A new symmetrized S-band rf gun, using a Mg photocathode, will produce up to 1 nC of charge in an 8 ps bunch, with a normalized emittance modeled at 0.8 mm.mrad; electrons are subsequently accelerated up to 120 MeV to interact with a 500 mJ, 10 ps, 355 nm laser pulse and generate {gamma}-rays. The laser front end is a fiber-based system, using corrugated-fiber Bragg gratings for stretching, and drives both the frequency-quadrupled photocathode illumination laser and the Nd:YAG interaction laser. Two new technologies are used in the laser: a hyper-Michelson temporal pulse stacker capable of producing 8 ps square UV pulses, and a hyper-dispersion compressor for the interaction laser. Other key technologies, basic scaling laws, and recent experimental results will also be presented, along with an overview of future research and development directions.

Hartemann, F V; Anderson, S G; Gibson, D J; Hagmann, C A; Johnson, M S; Jovanovic, I; Messerly, M J; Pruet, J A; Shverdin, M Y; Tremaine, A M; McNabb, D P; Siders, C W; Barty, C J

2007-08-15

125

Laser Compton scattering experiments and the latest developments in construction of experimental facilities at SINAP  

NASA Astrophysics Data System (ADS)

In this article, we report the two terms Laser Compton Scattering (LCS) via interaction experiments at 100 MeV linear accelerator of SINAP. The monochromatic X-rays were generated by a 108.1 MeV, 2.5 ns electron beam colliding with two Nd:YAG lasers of 113mJ/pulse,35 ns and 2J/pulse, 10 ns, respectively, and demonstrate the latest developments in construction of experimental facilities at SINAP: a high-intensity ultrafast laser and electron interaction experimental facility based on Shanghai Deep Ultraviolet-Free Electron Laser (SDUV-FEL) device. In addition, we present a future Laser Compton Scattering (LCS) ?-ray source - Shanghai Laser Electron Gamma Source (SLEGS) at Shanghai Synchrotron Radiation Facility (SSRF) is presented. It is one of beamlines of SSRF in Phase II and will be finished around 2011. Key words: Laser Compton Scattering (LCS); Shanghai Laser Electron Gamma Source (SLEGS); 100MeV & 150MeV Linac; Shanghai Synchrotron Radiation Facility (SSRF);

Luo, W.; Xu, W.; Pan, Q. Y.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Lin, G. Q.; Xu, B. J.; Xu, Y.; Yan, Z.; Yang, L. F.

2009-07-01

126

Compton scattering polarimeter "PENGUIN" for solar flares polarimetry  

NASA Astrophysics Data System (ADS)

Compton scattering polarimeter is discussed. This instrument will be used for linear polarization measurements of solar flares in energy range from 20keV to 150keV. Scattering detector consists of a number of p-terphenil crystals with total square 120cm2 and thickness 3cm. The detectors of scattered radiation are CsJ(Na)-based crystals. All detectors are enclosed anticoincidence shields in order to avoid charge particle background. The estimations of efficiency are made by means of Monte-Carlo simulation. Proposed accuracy of polarization measurements is near 10±1%. The stabilization system is used to keep threshold levels not more 1%.

Kotov, Y. D.; Kruglov, E. M.; Khmylko, V. V.; Chichikaluk, Y. A.

2001-08-01

127

LLNL Precision Compton Scattering Light Source: X-band RF Photoinjector and Accelerator Design  

NASA Astrophysics Data System (ADS)

The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. This precision light source with up to 2.5 MeV photon energy is currently being built at LLNL using high gradient X-band accelerator technology in collaboration with SLAC. The design of a high brightness 5.59 cell X-band RF photoinjector will be presented. An ``early light'' machine has been designed using the 250 pC, <1mm-mrad electron bunches from the photoinjector, a single T53 traveling wave accelerator section, and Joule-class diode pumped laser pulses to produce diagnostic Compton scattered photons. Design of this ``early-light'' machine will be presented with discussion of the various components, layout considerations, and plans for the full 250 MeV linear accelerator.

Marsh, Roark; Anderson, S. G.; Gibson, D. J.; Wu, S. S.; Hartemann, F. V.; Houck, T. L.; Ebbers, C.; Scarpetti, R. D.; Barty, C. P. J.; Adolphsen, C.; Chu, T. S.; Li, Z.; Tantawi, S. G.; Vlieks, A. E.; Wang, J. W.; Raubenheimer, T. O.

2010-11-01

128

Design of narrow-band Compton scattering sources for nuclear resonance fluorescence  

NASA Astrophysics Data System (ADS)

The design of narrow-band Compton scattering sources for specific applications using nuclear resonance fluorescence (NRF) is presented. NRF lines are extremely narrow (?E/?10-6) and require spectrally narrow sources to be excited selectively and efficiently. This paper focuses on the theory of spectral broadening mechanisms involved during Compton scattering of laser photons from relativistic electron beams. It is shown that in addition to the electron beam emittance, energy spread, and the laser parameters, nonlinear processes during the laser-electron interaction can have a detrimental effect on the gamma-ray source bandwidth, including a newly identified weakly nonlinear phase shift accumulated over the effective interaction duration. Finally, a design taking these mechanisms into consideration is outlined.

Albert, F.; Anderson, S. G.; Gibson, D. J.; Marsh, R. A.; Wu, S. S.; Siders, C. W.; Barty, C. P. J.; Hartemann, F. V.

2011-05-01

129

Design and operation of a tunable MeV-level Compton-scattering-based ?-ray source  

NASA Astrophysics Data System (ADS)

A monoenergetic gamma-ray (MEGa-ray) source based on Compton scattering, targeting nuclear physics applications such as nuclear resonance fluorescence, has been constructed and commissioned at Lawrence Livermore National Laboratory. In this paper, the overall architecture of the system, as well as some of the design decisions (such as laser pulse lengths and interaction geometry) made in the development of the source, are discussed. The performances of the two laser systems (one for electron production, one for scattering), the electron photoinjector, and the linear accelerator are also detailed, and initial ?-ray results are presented.

Gibson, D. J.; Albert, F.; Anderson, S. G.; Betts, S. M.; Messerly, M. J.; Phan, H. H.; Semenov, V. A.; Shverdin, M. Y.; Tremaine, A. M.; Hartemann, F. V.; Siders, C. W.; McNabb, D. P.; Barty, C. P. J.

2010-07-01

130

Expected level of self-Compton scattering in radio loud quasars  

NASA Technical Reports Server (NTRS)

Radio-loud quasars usually contain parsec-scale nonthermal jets. The most compact emission region ('the core'), and perhaps some of the moving 'knots', are expected to be efficient producers of inverse Compton scattered X-rays and gamma-rays since many of the synchrotron photons will upscatter before escaping. Through multifrequency flux density observations and Very Long Baseline Interferometry (VLBI) measurements of angular sizes, one can predict the flux density of this self-Compton high-energy emission. It is not always the case that the brightest synchrotron sources are also the brightest X-ray and gamma-ray sources. Perhaps a better predictor of high-energy brightness is the ratio of hard X-ray to high-frequency radio emission. Using the synchrotron self-Compton relations, we predict the gamma-ray fluxes of several sources we expect to be detected by the Energetic Gamma Ray Experiment Telescope (EGRET). More accurate predictions will be made when we complete a program of contemporaneous radio-submillimeter and X-ray observations during the course of the EGRET all-sky survey.

Bloom, Steven D.; Marscher, Alan P.

1992-01-01

131

Precise polarization measurements via detection of compton scattered electrons  

SciTech Connect

The Qweak experiment at Jefferson Lab aims to make a 4% measurement of the parity-violating asymmetry in elastic scattering at very low Q{sup 2} of a longitudinally polarized electron beam off a proton target. One of the dominant experimental systematic uncertainties in Qweak will result from determining the beam polarization. A new Compton polarimeter was installed in the fall of 2010 to provide a non-invasive and continuous monitoring of the electron beam polarization in Hall C at Jefferson Lab. The Compton-scattered electrons are detected in four planes of diamond micro-strip detectors. We have achieved the design goals of <1% statistical uncertainty per hour and expect to achieve <1% systematic uncertainty.

Tvaskis, Vladas [Manitoba Univ., Winnepeg (Canada); Dutta, Dipangkar [Mississippi State Univ., MS (United States); Gaskell, David J. [JLAB, Newport News, VA (United States); Narayan, Amrendra [Mississippi State Univ., MS (United States)

2014-01-01

132

Precise polarization measurements via detection of compton scattered electrons  

NASA Astrophysics Data System (ADS)

The Qweak experiment at Jefferson Lab aims to make a 4% measurement of the parity-violating asymmetry in elastic scattering at very low Q 2 of a longitudinally polarized electron beam off a proton target. One of the dominant experimental systematic uncertainties in Qweak will result from determining the beam polarization. A new Compton polarimeter was installed in the fall of 2010 to provide a non-invasive and continuous monitoring of the electron beam polarization in Hall C at Jefferson Lab. The Compton-scattered electrons are detected in four planes of diamond micro-strip detectors. We have achieved the design goals of <1% statistical uncertainty per hour and expect to achieve <1% systematic uncertainty.

Tvaskis, V.; Dutta, D.; Gaskell, D.; Narayan, A.

2014-01-01

133

Polarization Transfer in Proton Compton Scattering at High Momentum Transfer  

Microsoft Academic Search

Compton scattering from the proton was investigated at s = 6.9 GeV² and t = -4.0 TeV² via polarization transfer from circularly polarized incident photons. The longitudinal and transverse components of the recoil proton polarization were measured. The results are in excellent agreement with a prediction based on a reaction mechanism in which the photon interacts with a single quark

D. J. Hamilton; Vahe Mamyan

2004-01-01

134

Real Compton Scattering on Proton at High Momentum Transfers  

Microsoft Academic Search

The E99-114 experiment was carried out to measure the cross sections for Real Compton Scattering (RCS) on the proton in the kinematic range s = 5-11 GeV², -t = 2-7 GeV². In addition, a measurement of longitudinal and transverse polarization transfers was made at s = 6.9 GeV² and -t = 4.0 GeV². These measurements were done to test the

A. Danagoulian; D. J. Hamilton; C. E. Hyde-Wright; V. H. Mamyan; A. M. Nathan; M. Roedelbronn; B. Wojtsekhowski

2005-01-01

135

Investigating Neutron Polarizabilities Through Compton Scattering on Light Nuclei  

NASA Astrophysics Data System (ADS)

This talk will focus on elastic Compton scattering on deuteron and He-3 as an instrument to extract the neutron polarizabilities. The calculations for this process have been performed for photon energies comparable to the pion mass within the framework of Chiral effective field theory. The results show that these computations, when used in concert with future data from MAXLab and HIGS, should give significant new information about the neutron polarizabilities.

Shukla, Deepshikha

2008-10-01

136

Magnetic properties of Ga doped cobalt ferrite: Compton scattering study  

NASA Astrophysics Data System (ADS)

We present the spin momentum density of Ga doped CoFe2O4 at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe2O4.

Sharma, Arvind; Sahariya, Jagrati; Mund, H. S.; Itou, M.; Sakurai, Y.; Ahuja, B. L.

2014-04-01

137

Covariant Compton scattering kernel in general relativistic radiative transfer  

NASA Astrophysics Data System (ADS)

A covariant scattering kernel is a core component in any self-consistent general relativistic radiative transfer formulation in scattering media. An explicit closed-form expression for a covariant Compton scattering kernel with a good dynamical energy range has unfortunately not been available thus far. Such an expression is essential in obtaining numerical solutions to the general relativistic radiative transfer equations in complicated astrophysical settings where strong scattering effects are coupled with highly relativistic flows and steep gravitational gradients. Moreover, this must be performed in an efficient manner. With a self-consistent covariant approach, we have derived a closed-form expression for the Compton scattering kernel for an arbitrary energy range. The scattering kernel and its angular moments are expressed in terms of hypergeometric functions, and their derivations are shown explicitly in this paper. We also evaluate the kernel and its moments numerically, assessing various techniques for their calculation. Finally, we demonstrate that our closed-form expression produces the same results as previous calculations, which employ fully numerical computation methods and are applicable only in more restrictive settings.

Younsi, Ziri; Wu, Kinwah

2013-08-01

138

Laser-assisted Compton scattering of x-ray photons  

NASA Astrophysics Data System (ADS)

The Compton scattering of x-ray photons, assisted by a short intense optical laser pulse, is discussed. The differential scattering cross section reveals the interesting feature that the main Klein-Nishina line is accompanied by a series of side lines forming a broad plateau where up to O (103) laser photons participate simultaneously in a single scattering event. An analytic formula for the width of the plateau is given. Due to the nonlinear mixing of x-ray and laser photons a frequency-dependent rotation of the polarization of the final-state x-ray photons relative to the scattering plane emerges. A consistent description of the scattering process with short laser pulses requires to work with x-ray pulses. An experimental investigation can be accomplished, e.g., at LCLS or the European XFEL, in the near future.

Seipt, D.; Kämpfer, B.

2014-02-01

139

Testing photons' Bose-Einstein statistics with Compton scattering  

SciTech Connect

It is an empirical question whether photons always obey Bose-Einstein statistics, but devising and interpreting experimental tests of photon statistics can be a challenge. The nonrelativistic cross section for Compton scattering illustrates how a small admixture {nu} of wrong-sign statistics leads to a loss of gauge invariance; there is a large anomalous amplitude for scattering timelike photons. Nevertheless, one can interpret the observed transparency of the solar wind plasma at low frequencies as a bound {nu}<10{sup -25} if Lorentz symmetry is required. If there is instead a universal preferred frame, the bound is {nu}<10{sup -14}, still strong compared with previous results.

Altschul, Brett [Department of Physics and Astronomy, University of South Carolina, Columbia, South Carolina 29208 (United States)

2010-11-15

140

Polarisation Transfer in Proton Compton Scattering at High Momentum Transfer  

SciTech Connect

The Jefferson Lab Hall A experiment E99-114 comprised a series of measurements to explore proton Compton scattering at high momentum transfer. For the first time, the polarisation transfer observables in the p (~ 0 ~ p) reaction were measured in the GeV energy range, where it is believed that quark-gluon degrees of freedom begin to dominate. The experiment utilised a circularly polarised photon beam incident on a liquid hydrogen target, with the scattered photon and recoil proton detected in a lead-glass calorimeter and a magnetic spectrometer, respectively.

David Hamilton

2004-12-31

141

An effective field theory approach to Compton scattering in plasma  

NASA Astrophysics Data System (ADS)

We study Compton scattering in plasma medium via an effective field theory, by incorporating the contributions of longitudinal as well as transverse permittivities with their temperature dependent dispersive terms. We show that the introduction of the longitudinal mode not only increases the cross-section many-fold than in the case of vacuum, but also leads as a consequence to a well collimated and mono-energetic spectrum of scattered electrons, with the divergence ?6 mrad, suggesting that this approach has potential application to laser plasma accelerators.

Kumar, Ravindra; Ravishankar, V.; Krishan, V.

2012-06-01

142

Collective resonant Compton scattering by two-level particles  

NASA Astrophysics Data System (ADS)

In this paper we provide a simple analytical demonstration that an unbunched beam of two-level particles coherently driven by a quasi-resonant counterpropagating field can give rise to coherent Compton back scattering due to self bunching which occurs via an instability very similar to that of a high gain Free Electron Laser. Since the initially weak scattering light is exponentially amplified and is Doppler upshifted in frequency, this effect constitutes the basic physical principle of a tunable source of coherent radiation: the Collective Atomic Recoil Laser (CARL). CARL extends the FEL bunching concept to any system of particles having two internal energy levels.

Bonifacio, R.; De Salvo, L.

1995-02-01

143

Density and temperature effects on Compton scattering in plasmas  

SciTech Connect

We study the effect of the density and temperature on Compton scattering in a plasma, with particular emphasis on the quality of the scattered electron beam. We find that the longitudinal mode in the plasma plays a dominant role in producing collimated and mono-energetic electron spectrum. The beam profile is, however, sensitive to the plasma parameters such as its density and temperature. We make a careful study of this sensitivity and distinguish regions in the parameter space in which the quality of the beam profile is good from the regions in which it is poor. These findings are potentially useful in understanding the physics of laser plasma accelerators.

Kumar, Ravindra [Department of Physics, Indian Institute of Technology, Kanpur, Kanpur 208016 (India); Ravishankar, V. [Department of Physics, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi -110016 (India); Krishan, V. [Raman Research Institute, Bangalore 560080 (India)

2012-09-15

144

Generation and application of Laser-Compton gamma-ray at ETL  

Microsoft Academic Search

Laser-Compton gamma-ray facility has been developed at Electrotechnical Laboratory. Generation of the Laser-Compton gamma-ray and its applications for the establishment of the standard field of high-energy gamma-rays, for the nuclear physics research and for the beam diagnostic of the electron beam circulating in the storage ring is presented.

Hideaki Ohgaki; Hiroyuki Toyokawa; Katsuhisa Kudo; Naoto Takeda; Tetsuo Yamazaki

2000-01-01

145

Charge-ordering in Magnetite studied by Magnetic Compton scattering  

NASA Astrophysics Data System (ADS)

We present the [100]-[110] anisotropy of the magnetic Compton profile (MCP) in magnetite (Fe3O4). Good agreement is found between theory (within the local spin density approximation) and experiment with respect to the anisotropy in the metallic phase at 300K. However, the experimental curve for the insulating phase at 12K presents important changes at the low-momentum peak near 1 a.u. indicating that the bonding electrons are significantly affected by the Verwey transition. We will discuss whether these MCP anisotropy changes can be explained in terms of a charge-ordering mitigated by covalent effects [1]. Our study illustrates the high sensitivity of the Magnetic Compton scattering technique for extracting information on the electrons involved in the Verwey transition. Work supported in part by U.S. DOE. [1] M. Coey, Nature 430, 155 (2004)

Barbiellini, B.; Kobayashi, H.; Itou, M.; Todo, S.; Mijnarends, P. E.; Bansil, A.

2009-03-01

146

Magnetic Compton-induced pair cascade model for gamma-ray pulsars  

NASA Technical Reports Server (NTRS)

Electrons accelerated to relativistic energies in pulsar magnetospheres will Compton scatter surface thermal emission and nonthermal optical, UV, and soft X-ray emission to gamma-ray energies, thereby initiating a pair cascade through synchrotron radiation and magnetic pair production. This process is proposed as the origin of the high-energy radiation that has been detected from six isolated pulsars. We construct an analytic model of magnetic Compton scattering near the polar cap of isolated pulsar magnetospheres and present approximate analytic derivations for scattered spectra, electron energy-loss rates, and photon luminosities. A Monte Carlo simulation is used to model the pair cascade induced by relativistic electrons scattering photons through the cyclotron resonance. For simplicity, the primary electrons are assumed to be monoenergetic and the nonresonant emission is omitted. Assuming that the angle phi(sub B) between the magnetic and spin axes is approximately equal to the polar-cap angle theta(sub pc), this model can produce both double-peaked and broad single-peaked pulse profiles and account for the trend of harder gamma-ray spectra observed from older pulsars.

Sturner, Steven J.; Dermer, Charles D.; Michel, F. Curtis

1995-01-01

147

Three-Dimensional Theory of Nonlinear Compton Scattering  

NASA Astrophysics Data System (ADS)

For visible laser wavelengths, at intensities exceeding 10^17 W/cm^2, Compton scattering becomes a nonlinear process, whereby the probability of coherent multiphoton scattering is large, and the effects of radiation pressure dominate the electron dynamics during the interaction. This process has been studied in the single-particle plane-wave limit^1, where focusing, diffraction, Guoy phase, and the electron beam phase space are ignored; novel phenomena, including anharmonic radiation, and multiphoton scattering are predicted in this regime, and were observed for electrons initially at rest^2, or indirectly^3. A fully three-dimensional analysis is presented here, as well as experimental plans for a test of the theory. Finally, a new approach to nonlinear Compton scattering, relying on temporal laser pulse-shaping in circular polarization, will also be discussed, with the potential to generate extremely bright, hard x-rays required for in situ material probing and advanced backlighting applications. 1. F.V. Hartemann, "High-Field Electrodynamics", CRC Press (2002). 2. S-y Chen, A. Maksimchuk, D. Umstadter, Nature 396, p. 653 (1998). 3. C. Bula, et al., Phys. Rev. Lett., Vol. 76, p. 3116 (1996). This work is supported under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48, and by the National Undergraduate Fusion program.

Hartemann, Fred; Brown, Winthrop; Anderson, Scott; Brown, Jeremy; Crane, John; Gibson, Dave; Tremaine, Aaron

2003-10-01

148

The polarization effect of a laser in multiphoton Compton scattering  

NASA Astrophysics Data System (ADS)

The multiphoton Compton scattering in a high-intensity laser beam is studied by using the laser-dressed quantum electrodynamics (QED) method, which is a non-perturbative theory for the interaction between a plane electromagnetic field and a charged particle. In order to analyze in the real experimental condition, a Lorentz transformation for the cross section of this process is derived between the laboratory frame and the initial rest frame of electrons. The energy of the scattered photon is analyzed, as well as the cross sections for different laser intensities and polarizations and different electron velocities. The angular distribution of the emitted photon is investigated in a special velocity of the electron, in which for a fixed number of absorbed photons, the electron energy will not change after the scattering in the lab frame. We obtain the conclusion that higher laser intensities suppress few-laser-photon absorption and enhance more-laser-photon absorption. A comparison between different polarizations is also made, and we find that the linearly polarized laser is more suitable to generate nonlinear Compton scattering.

Liang, Guo-Hua; Lü, Qing-Zheng; Teng, Ai-Ping; Li, Ying-Jun

2014-05-01

149

Analysis of position-dependent Compton scatter in scintimammography with mild compression  

SciTech Connect

In breast scintigraphy using /sup 99m/Tc-sestamibi the relatively low radiotracer uptake in the breast compared to that in other organs such as the heart results in a large fraction of the detected events being Compton scattered gamma-rays. In this study, our goal was to determine whether generalized conclusions regarding scatter-to-primary ratios at various locations within the breast image are possible, and if so, to use them to make explicit scatter corrections to the breast scintigrams. Energy spectra were obtained from patient scans for contiguous regions of interest (ROIs) centered left to right within the image of the breast, and extending from the chest wall edge of the image to the anterior edge. An anthropomorphic torso phantom with fillable internal organs and a compressed-shape breast containing water only was used to obtain realistic position-dependent scatter-only spectra. For each ROI, the measured patient energy spectrum was fitted with a linear combination of the scatter-only spectrum from the anthropomorphic phantom and the scatter-free spectrum from a point source. We found that although there is a very strong dependence on location within the breast of the scatter-to-primary ratio, the spectra are well modeled by a linear combination of position-dependent scatter-only spectra and a position-independent scatter-free spectrum, resulting in a set of position-dependent correction factors. These correction factors can be used along with measured emission spectra from a given breast to correct for the Compton scatter in the scintigrams. However, the large variation among patients in the magnitude of the position-dependent scatter makes the success of universal correction approaches unlikely.

Mark Williams; Deepa Narayanan; Mitali J. More; Patricia J. Goodale; Stanislaw Majewski; Douglas Kieper

2003-10-01

150

Separation of proton polarizabilities with the beam asymmetry of compton scattering.  

PubMed

We propose to determine the magnetic dipole polarizability of the proton from the beam asymmetry of low-energy Compton scattering based on the fact that the leading non-Born contribution to the asymmetry is given by the magnetic polarizability alone; the electric polarizability cancels out. The beam asymmetry thus provides a simple and clean separation of the magnetic polarizability from the electric one. Introducing polarizabilities in a Lorentz-invariant fashion, we compute the higher-order (recoil) effects of polarizabilities on beam asymmetry and show that these effects are suppressed in forward kinematics. With the prospects of precision Compton experiments at the Mainz Microtron and High Intensity Gamma Source facilities in mind, we argue why the beam asymmetry could be the best way to measure the elusive magnetic polarizability of the proton. PMID:23848863

Krupina, Nadiia; Pascalutsa, Vladimir

2013-06-28

151

Observing atom motion by electron-atom Compton scattering  

NASA Astrophysics Data System (ADS)

A very elemental method of observing the motion of the nucleus in molecules or solids is described. The observations for copper, graphite, and formvar films can be understood assuming that the electrons scatter from a moving target (vibrating atoms). The method is the complete electron analog for neutron Compton scattering. The nuclear motion causes a doppler shift in the energy of elastically scattered electrons. It is rather unusual among the methods of studying vibrations (e.g., molecular vibrations in individual molecules or phonons in solids) in that the information obtained is directly related to the momentum distribution of the probed atoms, rather than the energy difference between different vibrational states. The application of the semiclassical picture described here could fail to describe more detailed measurements. Gas-phase experiments may be more suitable for fully quantitative measurements. Indeed the experiment could be used to study the breakup of molecules after a well-defined perturbation.

Vos, Maarten

2002-01-01

152

Interpretation of a ?-Compton densitometer response from multi-scattered photons  

NASA Astrophysics Data System (ADS)

A detailed Monte Carlo simulation of the gamma Compton scattering process was performed in order to better understand the global phenomena and to improve the interpretation of a ?-Compton densitometer's response. The experimental set up consists of a mono-energetic gamma ray source (137Cs), a BGO detector (sensitive volume of 3" x 3"), a set of pieces of lead (shielding), a standard electronic signal chain for the energy spectrum acquisition and a material under study (Portland Concrete). The Monte Carlo code, PENELOPE 2008, was modified to obtain additional information, about the "detected" photons, that can be useful to understand the relevance of the number of Compton interactions for each primary photon, and so better interpret the count rate and the shape of the acquired spectrum. It is shown that all this new information added to the total energy spectrum can help not only to determine the bulk density of concrete but also it can help to identify non-homogeneous zones, with very low density in comparison to the concrete density, like cavities, pipes, etc.

Pino, F.; Barros, H.; Sajo-Bohus, L.; Palacios, D.

2012-02-01

153

Measurement of deeply virtual Compton scattering at HERA  

Microsoft Academic Search

The cross-section for deeply virtual Compton scattering in the reaction ep?e?p has been measured with the ZEUS detector at HERA using integrated luminosities of 95.0 pb?1 of e+p and 16.7 pb?1 of e?p collisions. Differential cross-sections are presented as a function of the exchanged-photon virtuality, Q2, and the centre-of-mass energy, W, of the ??p system in the region 5

S. Bhadra; C. D. Catterall; S. Fourletov; G. Hartner; S. Magill; M. Soares; J. Standage; R. Yoshida; M. C. K. Mattingly; P. Antonioli; G. Bari; M. Basile; L. Bellagamba; D. Boscherini; A. Bruni; G. Bruni; G. Cara Romeo; L. Cifarelli; F. Cindolo; A. Contin; M. Corradi; S. de Pasquale; P. Giusti; G. Iacobucci; A. Margotti; R. Nania; F. Palmonari; A. Pesci; G. Sartorelli; A. Zichichi; G. Aghuzumtsyan; D. Bartsch; I. Brock; S. Goers; H. Hartmann; E. Hilger; P. Irrgang; H.-P. Jakob; A. Kappes; U. F. Katz; O. Kind; U. Meyer; E. Paul; J. Rautenberg; R. Renner; A. Stifutkin; J. Tandler; K. C. Voss; M. Wang; A. Weber; D. S. Bailey; N. H. Brook; J. E. Cole; B. Foster; G. P. Heath; H. F. Heath; S. Robins; E. Rodrigues; J. Scott; R. J. Tapper; M. Wing; M. Capua; A. Mastroberardino; M. Schioppa; G. Susinno; J. Y. Kim; Y. K. Kim; J. H. Lee; I. T. Lim; M. Y. Pac; A. Caldwell; M. Helbich; X. Liu; B. Mellado; Y. Ning; S. Paganis; Z. Ren; W. B. Schmidke; F. Sciulli; J. Chwastowski; A. Eskreys; J. Figiel; K. Olkiewicz; P. Stopa; L. Zawiejski; L. Adamczyk; T. Bold; I. Grabowska-Bold; D. Kisielewska; A. M. Kowal; M. Kowal; T. Kowalski; M. Przybycien; L. Suszycki; D. Szuba; J. Szuba; A. Kotanski; W. Slominski; V. Adler; L. A. T. Bauerdick; U. Behrens; I. Bloch; K. Borras; V. Chiochia; D. Dannheim; G. Drews; J. Fourletova; U. Fricke; A. Geiser; P. Göttlicher; O. Gutsche; T. Haas; W. Hain; S. Hillert; B. Kahle; U. Kötz; H. Kowalski; G. Kramberger; H. Labes; D. Lelas; B. Löhr; R. Mankel; I.-A. Melzer-Pellmann; M. Moritz; C. N. Nguyen; D. Notz; M. C. Petrucci; A. Polini; A. Raval; U. Schneekloth; F. Selonke; U. Stoesslein; H. Wessoleck; G. Wolf; C. Youngman; W. Zeuner; S. Schlenstedt; G. Barbagli; E. Gallo; C. Genta; P. G. Pelfer; A. Bamberger; A. Benen; N. Coppola; M. Bell; P. J. Bussey; A. T. Doyle; C. Glasman; S. Hanlon; S. W. Lee; A. Lupi; D. H. Saxon; I. O. Skillicorn; I. Gialas; B. Bodmann; T. Carli; U. Holm; K. Klimek; N. Krumnack; E. Lohrmann; M. Milite; H. Salehi; S. Stonjek; K. Wick; A. Ziegler; C. Collins-Tooth; C. Foudas; R. Goncalo; K. R. Long; A. D. Tapper; P. Cloth; D. Filges; K. Nagano; K. Tokushuku; S. Yamada; Y. Yamazaki; A. N. Barakbaev; E. G. Boos; N. S. Pokrovskiy; B. O. Zhautykov; H. Lim; D. Son; K. Piotrzkowski; F. Barreiro; O. González; L. Labarga; J. del Peso; E. Tassi; J. Terrón; M. Vázquez; M. Barbi; F. Corriveau; S. Gliga; J. Lainesse; S. Padhi; D. G. Stairs; T. Tsurugai; A. Antonov; P. Danilov; B. A. Dolgoshein; D. Gladkov; V. Sosnovtsev; S. Suchkov; R. K. Dementiev; P. F. Ermolov; Yu. A. Golubkov; I. I. Katkov; L. A. Khein; I. A. Korzhavina; V. A. Kuzmin; B. B. Levchenko; O. Yu. Lukina; A. S. Proskuryakov; L. M. Shcheglova; N. N. Vlasov; S. A. Zotkin; S. Grijpink; E. Koffeman; P. Kooijman; E. Maddox; A. Pellegrino; S. Schagen; H. Tiecke; J. J. Velthuis; L. Wiggers; E. de Wolf; N. Brümmer; B. Bylsma; L. S. Durkin; T. Y. Ling; A. M. Cooper-Sarkar; A. Cottrell; R. C. E. Devenish; J. Ferrando; G. Grzelak; S. Patel; M. R. Sutton; R. Walczak; A. Bertolin; R. Brugnera; R. Carlin; F. dal Corso; S. Dusini; A. Garfagnini; S. Limentani; A. Longhin; A. Parenti; M. Posocco; L. Stanco; M. Turcato; E. A. Heaphy; F. Metlica; B. Y. Oh; P. R. B. Saull; W. S. Toothacker; J. J. Whitmore; Y. Iga; G. D'Agostini; G. Marini; A. Nigro; C. Cormack; J. C. Hart; N. A. McCubbin; C. Heusch; I. H. Park; N. Pavel; H. Abramowicz; A. Gabareen; S. Kananov; A. Kreisel; A. Levy; M. Kuze; T. Abe; T. Fusayasu; S. Kagawa; T. Kohno; T. Tawara; T. Yamashita; R. Hamatsu; T. Hirose; M. Inuzuka; S. Kitamura; K. Matsuzawa; T. Nishimura; M. Arneodo; M. I. Ferrero; V. Monaco; M. Ruspa; R. Sacchi; A. Solano; T. Koop; G. M. Levman; J. F. Martin; A. Mirea; J. M. Butterworth; C. Gwenlan; R. Hall-Wilton; T. W. Jones; M. S. Lightwood; B. J. West; J. Ciborowski; R. Ciesielski; R. J. Nowak; J. M. Pawlak; J. Sztuk; T. Tymieniecka; A. Ukleja; J. Ukleja; A. F. Zarnecki; M. Adamus; P. Plucinski; Y. Eisenberg; L. K. Gladilin; D. Hochman; U. Karshon; M. Riveline; D. Kcira; S. Lammers; L. Li; D. D. Reeder; A. A. Savin; W. H. Smith; A. Deshpande; S. Dhawan; P. B. Straub; S. Menary

2003-01-01

154

Measurement of deeply virtual Compton scattering at HERA  

Microsoft Academic Search

A measurement is presented of elastic deeply virtual Compton scattering e++p?e++?+p at HERA using data taken with the H1 detector. The cross section is measured as a function of the photon virtuality, Q2, and the invariant mass, W, of the ?p system, in the kinematic range 2

C. Adloff; V. Andreev; B. Andrieu; T. Anthonis; V. Arkadov; A. Astvatsatourov; A. Babaev; J. Bähr; P. Baranov; E. Barrelet; W. Bartel; P. Bate; A. Beglarian; O. Behnke; C. Beier; A. Belousov; T. Benisch; Ch. Berger; T. Berndt; J. C. Bizot; V. Boudry; W. Braunschweig; V. Brisson; H.-B. Bröker; D. P. Brown; W. Brückner; D. Bruncko; J. Bürger; F. W. Büsser; A. Bunyatyan; G. Buschhorn; L. Bystritskaya; A. J. Campbell; S. Caron; D. Clarke; B. Clerbaux; C. Collard; J. G. Contreras; Y. R. Coppens; J. A. Coughlan; M.-C. Cousinou; B. E. Cox; G. Cozzika; J. Cvach; J. B. Dainton; W. D. Dau; K. Daum; M. Davidsson; B. Delcourt; N. Delerue; R. Demirchyan; C. Diaconu; J. Dingfelder; P. Dixon; V. Dodonov; J. D. Dowell; A. Droutskoi; C. Duprel; G. Eckerlin; D. Eckstein; V. Efremenko; S. Egli; R. Eichler; F. Eisele; E. Eisenhandler; M. Ellerbrock; E. Elsen; M. Erdmann; W. Erdmann; P. J. W. Faulkner; L. Favart; A. Fedotov; R. Felst; J. Ferencei; S. Ferron; M. Fleischer; Y. H. Fleming; G. Flügge; A. Fomenko; I. Foresti; J. Formánek; G. Franke; E. Gabathuler; K. Gabathuler; J. Garvey; J. Gassner; R. Gerhards; C. Gerlich; S. Ghazaryan; L. Goerlich; N. Gogitidze; M. Goldberg; C. Goodwin; C. Goodwin; H. Grässler; T. Greenshaw; G. Grindhammer; T. Hadig; D. Haidt; L. Hajduk; W. J. Haynes; B. Heinemann; G. Heinzelmann; R. C. W. Henderson; S. Hengstmann; H. Henschel; R. Heremans; G. Herrera; I. Herynek; M. Hildebrandt; K. H. Hiller; J. Hladký; P. Höting; D. Hoffmann; R. Horisberger; S. Hurling; M. Ibbotson; Ç. ??sever; M. Jacquet; L. Janauschek; X. Janssen; V. Jemanov; L. Jönsson; D. P. Johnson; M. A. S. Jones; H. Jung; H. K. Kästli; D. Kant; M. Kapichine; O. Karschnick; F. Keil; N. Keller; J. Kennedy; I. R. Kenyon; S. Kermiche; C. Kiesling; P. Kjellberg; M. Klein; C. Kleinwort; T. Kluge; G. Knies; B. Koblitz; S. D. Kolya; V. Korbel; P. Kostka; S. K. Kotelnikov; R. Koutouev; A. Koutov; H. Krehbiel; J. Kroseberg; K. Krüger; A. Küpper; T. Kuhr; T. Kur?a; R. Lahmann; D. Lamb; M. P. J. Landon; W. Lange; T. Laštovi?ka; P. Laycock; E. Lebailly; A. Lebedev; B. Leißner; R. Lemrani; V. Lendermann; S. Levonian; M. Lindstroem; B. List; E. Lobodzinska; B. Lobodzinski; A. Loginov; N. Loktionova; V. Lubimov; S. Lüders; D. Lüke; L. Lytkin; H. Mahlke-Krüger; N. Malden; E. Malinovski; I. Malinovski; R. Mara?ek; P. Marage; J. Marks; R. Marshall; H.-U. Martyn; J. Martyniak; S. J. Maxfield; D. Meer; A. Mehta; K. Meier; A. B. Meyer; H. Meyer; J. Meyer; P.-O. Meyer; S. Mikocki; D. Milstead; T. Mkrtchyan; R. Mohr; S. Mohrdieck; M. N. Mondragon; F. Moreau; A. Morozov; J. V. Morris; K. Müller; P. Mur??n; V. Nagovizin; B. Naroska; J. Naumann; Th. Naumann; G. Nellen; P. R. Newman; T. C. Nicholls; F. Niebergall; C. Niebuhr; O. Nix; G. Nowak; J. E. Olsson; D. Ozerov; V. Panassik; C. Pascaud; G. D. Patel; M. Peez; E. Perez; J. P. Phillips; D. Pitzl; R. Pöschl; I. Potachnikova; B. Povh; K. Rabbertz; G. Rädel; J. Rauschenberger; P. Reimer; B. Reisert; D. Reyna; C. Risler; E. Rizvi; P. Robmann; R. Roosen; A. Rostovtsev; S. Rusakov; K. Rybicki; D. P. C. Sankey; J. Scheins; F.-P. Schilling; D. Schmidt; S. Schmidt; M. Schneider; L. Schoeffel; A. Schöning; T. Schörner; V. Schröder; H.-C. Schultz-Coulon; K. Sedlák; F. Sefkow; V. Shekelyan; I. Sheviakov; L. N. Shtarkov; Y. Sirois; T. Sloan; P. Smirnov; Y. Soloviev; D. South; V. Spaskov; A. Specka; H. Spitzer; R. Stamen; B. Stella; J. Stiewe; U. Straumann; M. Swart; M. Taševský; V. Tchernyshov; S. Tchetchelnitski; G. Thompson; P. D. Thompson; N. Tobien; D. Traynor; P. Truöl; G. Tsipolitis; I. Tsurin; J. Turnau; J. E. Turney; E. Tzamariudaki; S. Udluft; M. Urban; A. Usik; S. Valkár; A. Valkárová; C. Vallée; S. Vassiliev; Y. Vazdik; A. Vichnevski; K. Wacker; R. Wallny; B. Waugh; G. Weber; M. Weber; D. Wegener; C. Werner; M. Werner; N. Werner; G. White; S. Wiesand; T. Wilksen; M. Winde; G.-G. Winter; Ch. Wissing; M. Wobisch; E. Wünsch; A. C. Wyatt; J. Žá?ek; J. Zálešák; Z. Zhang; A. Zhokin; F. Zomer; J. Zsembery; M. zur Nedden

2001-01-01

155

Polarization Transfer in Proton Compton Scattering at High Momentum Transfer  

NASA Astrophysics Data System (ADS)

Compton scattering from the proton was investigated at s=6.9 GeV2 and t=-4.0 GeV2 via polarization transfer from circularly polarized incident photons. The longitudinal and transverse components of the recoil proton polarization were measured. The results are in disagreement with a prediction of perturbative QCD based on a two-gluon exchange mechanism, but agree well with a prediction based on a reaction mechanism in which the photon interacts with a single quark carrying the spin of the proton.

Hamilton, D. J.; Mamyan, V. H.; Aniol, K. A.; Annand, J. R.; Bertin, P. Y.; Bimbot, L.; Bosted, P.; Calarco, J. R.; Camsonne, A.; Chang, G. C.; Chang, T.-H.; Chen, J.-P.; Choi, Seonho; Chudakov, E.; Danagoulian, A.; Degtyarenko, P.; de Jager, C. W.; Deur, A.; Dutta, D.; Egiyan, K.; Gao, H.; Garibaldi, F.; Gayou, O.; Gilman, R.; Glamazdin, A.; Glashausser, C.; Gomez, J.; Hansen, J.-O.; Hayes, D.; Higinbotham, D.; Hinton, W.; Horn, T.; Howell, C.; Hunyady, T.; Hyde-Wright, C. E.; Jiang, X.; Jones, M. K.; Khandaker, M.; Ketikyan, A.; Kubarovsky, V.; Kramer, K.; Kumbartzki, G.; Laveissière, G.; Lerose, J.; Lindgren, R. A.; Margaziotis, D. J.; Markowitz, P.; McCormick, K.; Meziani, Z.-E.; Michaels, R.; Moussiegt, P.; Nanda, S.; Nathan, A. M.; Nikolenko, D. M.; Nelyubin, V.; Norum, B. E.; Paschke, K.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Pomatsalyuk, R.; Punjabi, V. A.; Rachek, I.; Radyushkin, A.; Reitz, B.; Roche, R.; Roedelbronn, M.; Ron, G.; Sabatie, F.; Saha, A.; Savvinov, N.; Shahinyan, A.; Shestakov, Y.; Širca, S.; Slifer, K.; Solvignon, P.; Stoler, P.; Tajima, S.; Sulkosky, V.; Todor, L.; Vlahovic, B.; Weinstein, L. B.; Wang, K.; Wojtsekhowski, B.; Voskanyan, H.; Xiang, H.; Zheng, X.; Zhu, L.

2005-06-01

156

Flow shear induced Compton scattering of electron drift instability  

SciTech Connect

Plasma flow shear effects on nonlinear saturation of electron drift waves are analyzed in the weak turbulence regime. Flow shear can enhance ion Compton scattering of long wavelength electron drift waves not only by modifying the beat wave-ion resonance condition, but also via the radial dependence of linear susceptibility. A nonlinear dispersion relation is obtained as a solution of the radially nonlocal nonlinear eigenmode equation. At nonlinear saturation, the spectral intensity of the fluctuations scales with flow shear as ({partial derivative}V{var phi}/{partial derivative}r){sup {minus}2} in addition to the linear dependence on the linear growth rate.

Hahm, T.S.

1992-02-01

157

Flow shear induced Compton scattering of electron drift instability  

SciTech Connect

Plasma flow shear effects on nonlinear saturation of electron drift waves are analyzed in the weak turbulence regime. Flow shear can enhance ion Compton scattering of long wavelength electron drift waves not only by modifying the beat wave-ion resonance condition, but also via the radial dependence of linear susceptibility. A nonlinear dispersion relation is obtained as a solution of the radially nonlocal nonlinear eigenmode equation. At nonlinear saturation, the spectral intensity of the fluctuations scales with flow shear as ({partial_derivative}V{var_phi}/{partial_derivative}r){sup {minus}2} in addition to the linear dependence on the linear growth rate.

Hahm, T.S.

1992-02-01

158

X-ray spectrometer for observation of nonlinear compton scattering.  

SciTech Connect

An x-ray spectrometer, which consists of a multilayer device and a two-dimensional position sensitive detector, is designed for measurement of the x-ray energy spectrum and angular distribution from the nonlinear Compton scattering of 60 MeV electron and high power CO{sub 2} laser beams provided by a user facility at Brookhaven National Laboratory. A Prototype of the spectrometer has constructed and tested using isotropic 8 keV (Cu K{alpha}) x-rays from a sealed x-ray tube.

Kamiya, Y.; Kumita, T.; Siddons, D. P.; Ben-Zvi, I.; Liu, C.; Macrander, A. T.; Hirose, T.; Washio, M.; Omori, T.; Urakawa, J.; Yokoya, K.; Tokyo Metropolitan Univ.; BNL; Waseda Univ.; High Energy Accelerator Research Organization

2004-01-01

159

THE VERY HIGH ENERGY EMISSION FROM PULSARS: A CASE FOR INVERSE COMPTON SCATTERING  

SciTech Connect

The observations of gamma-ray emission from pulsars with the Fermi-LAT detector and the detection of the Crab pulsar with the VERITAS array of Cherenkov telescopes at energies above 100 GeV make it unlikely that curvature radiation is the main source of photons above GeV energies in the Crab and many other pulsars. We outline a model in which the broad UV-X-ray component and the very high energy {gamma}-ray emission of pulsars are explained within the synchrotron self-Compton framework. We argue that the bulk of the observed radiation is generated by the secondary plasma, which is produced in cascades in the outer gaps of the magnetosphere. We find that the inverse Compton (IC) scattering occurs in the Klein-Nishina regime, which favors synchrotron photons in the UV band as target field for the scattering process. The primary beam is accelerated in a modest electric field, with a field strength that is of the order of a few percent of the magnetic field near the light cylinder. Overall, for IC scattering occurring in the Klein-Nishina regime, the particle distribution in the gap does not evolve toward a stationary distribution and thus is intrinsically time-dependent. We point out that in a radiation reaction-limited regime of particle acceleration the gamma-ray luminosity L{sub {gamma}} scales linearly with the pulsar spin-down power E-dot , L{sub {gamma}}{proportional_to} E-dot , and not proportional to {radical}( E-dot ) as expected from potential-limited acceleration.

Lyutikov, Maxim [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States); Otte, Nepomuk [Santa Cruz Institute for Particle Physics and Department of Physics, University of California, Santa Cruz, CA 95060 (United States); McCann, Andrew [Department of Physics, McGill University, Montreal, QC, H3A 2T8 (Canada)

2012-07-20

160

Compton Scattering Cross Sections in Strong Magnetic Fields: Advances for Neutron Star Applications  

NASA Astrophysics Data System (ADS)

Various telescopes including RXTE, INTEGRAL, Suzaku and Fermi have detected steady non-thermal X-ray emission in the 10 ~ 200 keV band from strongly magnetic neutron stars known as magnetars. Magnetic inverse Compton scattering is believed to be a leading candidate for the production of this intense X-ray radiation. Generated by electrons possessing ultra-relativistic energies, this leads to attractive simplifications of the magnetic Compton cross section. We have recently addressed such a case by developing compact analytic expressions using correct spin-dependent widths acquired through the implementation of Sokolov & Ternov (ST) basis states, focusing specifically on ground state-to-ground state scattering. Such scattering in magnetar magnetospheres can cool electrons down to mildly-relativistic energies. Moreover, soft gamma-ray flaring in magnetars may well involve strong Comptonization in expanding clouds of mildly-relativistic pairs. These situations necessitate the development of more general magnetic scattering cross sections, where the incoming photons acquire substantial incident angles relative to the field in the rest frame of the electron, and the intermediate state can be excited to arbitrary Landau levels. Here, we highlight results from such a generalization using ST formalism. The cross sections treat the plethora of harmonic resonances associated with various cyclotron transitions between Landau states. Polarization dependence of the cross section for the four scattering modes is illustrated and compared with the non-relativistic Thompson cross section with classical widths. Results will find application to various neutron star problems, including computation of Eddington luminosities and polarization mode-switching rates in transient magnetar fireballs.We express our gratitude for the generous support of Michigan Space Grant Consortium, the National Science Foundation (grants AST-0607651, AST-1009725, AST-1009731 and PHY/DMR-1004811), and the NASA Astrophysics Theory Program through grants NNX06AI32G, NNX09AQ71G and NNX10AC59A.

Ickes, Jesse; Gonthier, Peter L.; Eiles, Matthew; Baring, Matthew G.; Wadiasingh, Zorawar

2014-08-01

161

Compton scattered imaging based on the V-line radon transform and its medical imaging applications.  

PubMed

The Radon transform (RT) on straight lines deals as mathematical foundation for many tomographic modalities (e.g. Xray scanner, Positron Emission Tomography), using only primary radiation. In this paper, we consider a new RT defined on a pair of half-lines forming a letter V, arising from the modeling a two-dimensional emission imaging process by Compton scattered gamma rays. We establish its analytic inverse, which is shown to support the feasibility of the reconstruction of a two-dimensional image from scattered radiation collected on a one-dimensional collimated camera. Moreover, a filtered back-projection inversion method is also constructed. Its main advantages are algorithmic efficiency and computational rapidity. We present numerical simulations to illustrate the working. To sum up, the V-line RT leads not only to a new imaging principle, but also to a new concept of detector with high energetic resolution capable to collect the scattered radiation. PMID:21095755

Nguyen, M K; Regniery, R; Truong, T T; Zaidi, H

2010-01-01

162

Optimization of a compton scatterer for hard x-ray weapons effects simulation in an ICF facility. Master's thesis  

SciTech Connect

This thesis examined the optimization of a Compton scatterer for use in simulating hard X-ray effects in the proposed Laboratory Microfusion Facility (LMF). The LMF will produce inertial confinement fusion of deuterium-tritium pellets. The Compton scatterer is designed to reflect the X rays produced from the fusion toward a target. The scatterer should produce the maximum X-ray dose at the target while minimizing the neutron dose and gamma production. The scatterer must also control the dose rate by spreading the X-ray pulse to achieve a full width at half maximum on the order of 10s of ns. The current geometry includes a spherical Compton scatterer made of lithium hydride enriched to 95.6% Lithium 6. This work explored various parabolic scatterers using Monte Carlo transport calculations performed on the MCNP computer program from Los Alamos National Lab. The parabolic shape was optimized to increased the X-ray dose at a silicone target by a factor of 7. The geometry also decreased the neutron and gamma doses to less than 1% of the X-ray dose while achieving an 80% uniformity of dose across a 1-meter-radius silicon disk.

Tinsley, R.L.

1990-03-01

163

Magnetic Compton scattering: A reliable probe to investigate magnetic properties  

NASA Astrophysics Data System (ADS)

Magnetic Compton scattering (MCS) is an ideal technique for the study of magnetic properties of ferro/ferrimagnetic materials because this method reveals the spin-polarized electron momentum density and yields the absolute and site dependent spin moments. The quantity measured in the MCS, so called magnetic Compton profile, is defined as the difference in the one-dimensional projection of the spin-polarized electron momentum density for majority and minority spin bands. In MCS, the Doppler broadening of the scattered radiation provides information on the correlation between the spin moment and the spin-polarized electron states of the valence electrons. It can also distinguish the spin polarization of itinerant electrons, because their momentum is narrow around the center of the profile. In this paper, temperature and field dependent spin momentum densities in Zn doped Ni ferrite namely, Ni1-xZnxFe2O4(x = 0.0,0.1,0.2), hole doped manganites like La0.7Ca0.3Mn1-xAlxO3(x = 0,0.02and0.06) and half Heusler alloys Cu1-xNixMnSb(x = 0.17,0.22) are reviewed. The decomposition of profiles in terms of site specific magnetic moments and their role in the formation of total spin moment is also discussed.

Ahuja, B. L.

2013-02-01

164

Beam normal spin asymmetry in the quasireal Compton scattering approximation  

SciTech Connect

The two-photon exchange contribution to the single spin asymmetries with the spin orientation normal to the reaction plane is discussed for elastic electron-proton scattering in the equivalent photon approximation. In this case, the hadronic part of the two-photon exchange amplitude describes real Compton scattering (RCS). We show that in the case of the beam normal spin asymmetry this approximation selects only the photon helicity flip amplitudes of RCS. At low energies, we make use of unitarity and estimate the contribution of the {pi}N multipoles to the photon helicity flip amplitudes. In the Regge regime, the quasi-RCS (QRCS) approximation allows for a contribution from two-pion exchange, and we provide an estimate of such contributions.

Gorchtein, M. [Genoa University, Department of Physics, I-16146 Genoa, Italy and California Institute of Technology, Pasadena, California 91125 (United States)

2006-05-15

165

120-Hz Diode-Pumped Kilowatt Class Laser for Compton Scattering Sources  

NASA Astrophysics Data System (ADS)

A Mono-Energetic Gamma-Ray (MEGa-ray) Compton scattering light source is currently based on a 120-Hz electron accelerator. A 120-Hz laser source can increase the current gamma ray production by more than an order of magnitude and further enhancements are possible. Diode pumped solid state lasers (DPSSLs) offer the potential to operate at these higher repetition rates where flash lamp pumped laser systems are currently limited by thermal and lamp lifetime issues. Utilizing LLNL expertise in high energy DPSSLs, a 10-J, 120-Hz diode-pumped Nd:YAG laser architecture has been developed. The laser design makes use of advances in diode packaging, power conditioning, and beam conditioning to provide over 100-kW peak power array. Sapphire heatsinks and longitudinal cooling of the amplifier yields low parasitic loss and low wavefront distortion. An image relayed architecture and adaptive optics will yield a diffraction limited beam ideal for Compton scattering. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Bayramian, Andy; Beer, Glenn; Campbell, Rob; Freitas, Barry; Molander, William; Sutton, Steve; Telford, Steve; Barty, Chris

2009-11-01

166

Virtual Compton scattering and neutral pion electroproduction in the resonance region up to the deep inelastic region at backward angles  

Microsoft Academic Search

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e, e'p)gamma exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q2=1GeV2 and for the Q2 dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions.

G. Laveissière; Natalie Degrande; Stephanie Jaminion; Christophe Jutier; Luminita Todor; Rachele Di Salvo; L. Van Hoorebeke; L. C. Alexa; Brian Anderson; Konrad Aniol; Kathleen Arundell; Gerard Audit; Leonard Auerbach; F. T. Baker; Maud Baylac; J. Berthot; Pierre Bertin; William Bertozzi; Louis Bimbot; Werner Boeglin; Edward Brash; Vincent Breton; Herbert Breuer; Etienne Burtin; John Calarco; Lawrence Cardman; Christian Cavata; C.-C. Chang; J.-P. Chen; E. Chudakov; E. Cisbani; D. S. Dale; C. W. de Jager; R. de Leo; A. Deur; N. D'Hose; G. E. Dodge; J. J. Domingo; L. Elouadrhiri; M. B. Epstein; L. A. Ewell; J. M. Finn; K. G. Fissum; H. Fonvieille; G. Fournier; B. Frois; S. Frullani; C. Furget; H. Gao; J. Gao; F. Garibaldi; A. Gasparian; S. Gilad; R. Gilman; A. Glamazdin; C. Glashausser; J. Gomez; V. Gorbenko; P. Grenier; P. A. M. Guichon; J. O. Hansen; R. Holmes; M. Holtrop; C. Howell; G. M. Huber; C. E. Hyde; S. Incerti; M. Iodice; J. Jardillier; M. K. Jones; W. Kahl; S. Kamalov; S. Kato; A. T. Katramatou; J. J. Kelly; S. Kerhoas; A. Ketikyan; M. Khayat; K. Kino; S. Kox; L. H. Kramer; K. S. Kumar; G. Kumbartzki; M. Kuss; A. Leone; J. J. Lerose; M. Liang; R. A. Lindgren; N. Liyanage; G. J. Lolos; R. W. Lourie; R. Madey; K. Maeda; S. Malov; D. M. Manley; C. Marchand; D. Marchand; D. J. Margaziotis; P. Markowitz; J. Marroncle; J. Martino; K. McCormick; J. McIntyre; S. Mehrabyan; F. Merchez; Z. E. Meziani; R. Michaels; G. W. Miller; J. Y. Mougey; S. K. Nanda; D. Neyret; E. A. J. M. Offermann; Z. Papandreou; C. F. Perdrisat; R. Perrino; G. G. Petratos; S. Platchkov; R. Pomatsalyuk; D. L. Prout; V. A. Punjabi; T. Pussieux; G. Quémenér; R. D. Ransome; O. Ravel; J. S. Real; F. Renard; Y. Roblin; D. Rowntree; G. Rutledge; P. M. Rutt; A. Saha; T. Saito; A. J. Sarty; A. Serdarevic; T. Smith; G. Smirnov; K. Soldi; P. Sorokin; P. A. Souder; R. Suleiman; J. A. Templon; T. Terasawa; L. Tiator; R. Tieulent; E. Tomasi-Gustaffson; H. Tsubota; H. Ueno; P. E. Ulmer; G. M. Urciuoli; R. Van de Vyver; P. Vernin; B. Vlahovic; H. Voskanyan; E. Voutier; J. W. Watson; L. B. Weinstein; K. Wijesooriya; R. Wilson; B. B. Wojtsekhowski; D. G. Zainea; W.-M. Zhang; J. Zhao; Z.-L. Zhou; Dan Zainea; Wei-Ming Zhang; Jie Zhao

2009-01-01

167

Correction of radiation absorption on biological samples using Rayleigh to Compton scattering ratio  

NASA Astrophysics Data System (ADS)

The aim of this work was to develop a method to correct the absorbed radiation (the mass attenuation coefficient curve) in low energy (E < 30 keV) applied to a biological matrix based on the Rayleigh to Compton scattering ratio and the effective atomic number. For calibration, scattering measurements were performed on standard samples of radiation produced by a gamma-ray source of 241Am (59.54 keV) also applied to certified biological samples of milk powder, hay powder and bovine liver (NIST 1557B). In addition, six methods of effective atomic number determination were used as described in literature to determinate the Rayleigh to Compton scattering ratio (R/C), in order to calculate the mass attenuation coefficient. The results obtained by the proposed method were compared with those obtained using the transmission method. The experimental results were in good agreement with transmission values suggesting that the method to correct radiation absorption presented in this paper is adequate for biological samples.

Pereira, Marcelo O.; Conti, Claudio de Carvalho; dos Anjos, Marcelino J.; Lopes, Ricardo T.

2012-06-01

168

Hadron Optics: Diffraction Patterns in Deeply Virtual Compton Scattering  

SciTech Connect

We show that the Fourier transform of the Deeply Virtual Compton Scattering (DVCS) amplitude with respect to the skewness variable {zeta} provides a unique way to visualize the light-front wavefunctions (LFWFs) of the target state in the boost-invariant longitudinal coordinate space variable ({sigma} = P{sup +}y{sup -}/2). The results are analogous to the diffractive scattering of a wave in optics in which the dependence of the amplitude on {sigma} measures the physical size of the scattering center of a one-dimensional system. If one combines this longitudinal transform with the Fourier transform of the DVCS amplitude with respect to the transverse momentum transfer {Delta}{sup {perpendicular}}, one can obtain a complete three-dimensional description of hadron optics at fixed light-front time {tau} = t + z/c. As a specific example, we utilize the quantum fluctuations of a fermion state at one loop in QED to obtain the behavior of the DVCS amplitude for electron-photon scattering. We then simulate the wavefunctions for a hadron by differentiating the above LFWFs with respect to M{sup 2} and study the corresponding DVCS amplitudes in {sigma} space.

Brodsky, S

2006-05-16

169

Compton Gamma Ray Observatory: Lessons Learned in Propulsion  

NASA Technical Reports Server (NTRS)

The Compton Gamma Ray Observatory was the second of NASA's Great Observatories. At 17 1/2 tons. it was the heaviest astrophysical payload ever flown at the time of its launch on April 5, 1991 aboard the Space Shuttle. During initial, on-orbit priming of the spacecraft's monopropellant hydrazine propulsion system, a severe waterhammer transient was experienced. At that time, anomalous telemetry readings were received from on-board propulsion system instrumentation. This led to ground analyses and laboratory investigations as to the root cause of the waterhammer, potential damage to system integrity and functionality, and risks for switching from the primary (A-side) propulsion system to the redundant (B-side) system. The switchover to B-side was ultimately performed successfully and the spacecraft completed its basic and extended missions in this configuration. Nine years later, following a critical control gyroscope failure, Compton was safely deorbited and re-entered the Earth's atmosphere on June 4, 2000. Additional risk assessments concerning viability of A- and B-sides were necessary to provide confidence in attitude and delta-V authority and reliability to manage the precisely controlled reentry. This paper summarizes the design and operation of the propulsion system used on the spacecraft and provides "lessons learned" from the system engineering investigations into the propellant loading procedures, the initial priming anomaly, mission operations, and the commanded re-entry following the gyro failure.

Dressler, G. A.; Joseph, G. W.; Behrens, H. W.; Asato, D. I.; Carlson, R. A.; Bauer, Frank H. (Technical Monitor)

2001-01-01

170

Observations of GRB 990123 by the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

GRB 990123 was the first burst from which simultaneous optical, X-ray, and gamma-ray emission was detected; its afterglow has been followed by an extensive set of radio, optical, and X-ray observations. We have studied the gamma-ray burst itself as observed by the Compton Gamma Ray Observatory detectors. We find that gamma-ray fluxes are not correlated with the simultaneous optical observations and that the gamma-ray spectra cannot be extrapolated simply to the optical fluxes. The burst is well fitted by the standard four-parameter GRB function, with the exception that excess emission compared with this function is observed below approx. 15 keV during some time intervals. The burst is characterized by the typical hard-to-soft and hardness-intensity correlation spectral evolution patterns. The energy of the peak of the vf (sub v), spectrum, E (sub p), reaches an unusually high value during the first intensity spike, 1470 plus or minus 110 keV, and then falls to approx. 300 keV during the tail of the burst. The high-energy spectrum above approx. 1 MeV is consistent with a power law with a photon index of about -3. By fluence, GRB 990123 is brighter than all but 0.4% of the GRBs observed with BATSE (Burst and Transient Source Experiment), clearly placing it on the -3/2 power-law portion of the intensity distribution. However, the redshift measured for the afterglow is inconsistent with the Euclidean interpretation of the -3/2 power law. Using the redshift value of greater than or equal to 1.61 and assuming isotropic emission, the gamma-ray energy exceeds 10 (exp 54) ergs.

Briggs, M. S.; Band, D. L.; Kippen, R. M.; Preece, R. D.; Kouveliotou, C.; vanParadijs, J.; Share, G. H.; Murphy, R. J.; Matz, S. M.; Connors, A.

1999-01-01

171

Recent progress in generation and application of AIST laser-Compton gamma-ray beam  

NASA Astrophysics Data System (ADS)

Quasi-monochromatic gamma-ray beam produced with the laser-Compton scattering (LCS) in 1-40 MeV has been used for various scientific studies and industrial applications in the National Institute of Advanced Industrial Science and Technology (AIST). We briefly overview the recent research progress in AIST. Since the first observation of the LCS gamma-ray beam in 1984 at AIST, photon generation techniques have been studied and improved. A beamline dedicated for user experiments was installed in FY 2000, and has been used by many users since then. There are many research programs being carried out using the LCS beamline, such as nuclear and atomic physics studies, radiation detector calibration and non-destructive tests.

Toyokawa, H.; Goko, S.; Hohara, S.; Kaihori, T.; Kaneko, F.; Kuroda, R.; Oshima, N.; Tanaka, M.; Koike, M.; Kinomura, A.; Ogawa, H.; Sei, N.; Suzuki, R.; Ohdaira, T.; Yamada, K.; Ohgaki, H.

2009-09-01

172

Measurement of deeply virtual compton scattering beam-spin asymmetries.  

PubMed

The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e p-->epgamma) were measured over a wide kinematic range and with high statistical accuracy. These asymmetries result from the interference of the Bethe-Heitler process and of deeply virtual Compton scattering. Over the whole kinematic range (x(B) from 0.11 to 0.58, Q2 from 1 to 4.8 GeV2, -t from 0.09 to 1.8 GeV2), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A approximately a sinphi/(1+c cosphi). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector. PMID:18518188

Girod, F X; Niyazov, R A; Avakian, H; Ball, J; Bedlinskiy, I; Burkert, V D; De Masi, R; Elouadrhiri, L; Garçon, M; Guidal, M; Jo, H S; Joo, K; Kubarovsky, V; Kuleshov, S V; MacCormick, M; Niccolai, S; Pogorelko, O; Sabatié, F; Stepanyan, S; Stoler, P; Ungaro, M; Zhao, B; Amaryan, M J; Ambrozewicz, P; Anghinolfi, M; Asryan, G; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Batourine, V; Battaglieri, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Blaszczyk, L; Bouchigny, S; Boiarinov, S; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Casey, L; Chen, S; Cheng, L; Cole, P L; Collins, P; Coltharp, P; Crabb, D; Crede, V; Dashyan, N; De Sanctis, E; De Vita, R; Degtyarenko, P V; Deur, A; Dharmawardane, K V; Dickson, R; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dugger, M; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Eugenio, P; Fedotov, G; Feldman, G; Funsten, H; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Goetz, J T; Gonenc, A; Gothe, R W; Griffioen, K A; Guler, N; Guo, L; Gyurjyan, V; Hafidi, K; Hakobyan, H; Hanretty, C; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Hyde, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Johnstone, J R; Juengst, H G; Kalantarians, N; Kellie, J D; Khandaker, M; Kim, W; Klein, A; Klein, F J; Klimenko, A V; Kossov, M; Krahn, Z; Kramer, L H; Kuhn, J; Kuhn, S E; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Lee, T; Livingston, K; Lu, H Y; Markov, N; Mattione, P; Mazouz, M; McKinnon, B; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Michel, B; Mikhailov, K; Mirazita, M; Miskimen, R; Mokeev, V; Moriya, K; Morrow, S A; Moteabbed, M; Munevar, E; Mutchler, G S; Nadel-Turonski, P; Nasseripour, R; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Nozar, M; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Anefalos Pereira, S; Pierce, J; Pivnyuk, N; Pocanic, D; Pozdniakov, S; Price, J W; Procureur, S; Prok, Y; Protopopescu, D; Raue, B A; Ricco, G; Ripani, M; Ritchie, B G; Rosner, G; Rossi, P; Salamanca, J; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabian, Y G; Sharov, D; Shvedunov, N V; Smith, E S; Smith, L C; Sober, D I; Sokhan, D; Stavinsky, A; Stepanyan, S S; Stokes, B E; Strakovsky, I I; Strauch, S; Taiuti, M; Tedeschi, D J; Tkabladze, A; Tkachenko, S; Tur, C; Vineyard, M F; Vlassov, A V; Voutier, E; Watts, D P; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Zana, L; Zhang, J; Zhao, Z W

2008-04-25

173

Laser-Compton Scattering as a Potential Electron Beam Monitor  

SciTech Connect

LCS experiments were carried out at the Idaho Accelerator Center (IAC); sharp monochromatic x-ray lines were observed. These are produced using the so-called inverse Compton effect, whereby optical laser photons are collided with a relativistic electron beam. The back-scattered photons are then kinematically boosted to keV x-ray energies. We have first demonstrated these beams using a 20 MeV electron beam collided with a 100 MW, 7 ns Nd; YAG laser. We observed narrow LCS x-ray spectral peaks resulting from the interaction of the electron beam with the Nd; YAG laser second harmonic (532 nm). The LCS x-ray energy lines and energy deviations were measured as a function of the electron beam energy and enery-spread respectively. The results showed good agreement with the predicted valves. LCS could provide an exellent probe of electron beam energy, energy spread, transverse and longitudinal distribution and direction.

Chouffani, K.; Wells, D.; Harmon, F.; Lancaster, G.; Jones, J.

2002-12-14

174

Real Compton Scattering on Proton at High Momentum Transfers  

SciTech Connect

The E99-114 experiment was carried out to measure the cross sections for Real Compton Scattering (RCS) on the proton in the kinematic range s = 5-11 GeV{sup 2}, -t = 2-7 GeV{sup 2}. In addition, a measurement of longitudinal and transverse polarization transfers was made at s = 6.9 GeV{sup 2} and -t = 4.0 GeV{sup 2}. These measurements were done to test the existing theoretical mechanisms for this process and will possibly lead to the determination of RCS form factors which are related to the Generalized Parton Distributions (GPD). The experiment was conducted in Hall A of Thomas Jefferson National Accelerator Facility (Jefferson Lab). Final results of polarization transfer measurements are presented.

A. Danagoulian; D.J. Hamilton; C.E. Hyde-Wright; V.H. Mamyan; A.M. Nathan; M. Roedelbronn; B. Wojtsekhowski

2005-06-01

175

Results on Deeply Virtual Compton Scattering at Jefferson Lab  

SciTech Connect

After about 10 years of growing interest for Generalized Parton Distributions come the first results from dedicated experiments, using the golden Deeply Virtual Compton Scattering process. After a short introduction, we will explain the experimental methodology and show results of the Hall A E00-110 experiment, which aimed at measuring helicity-dependent photon electroproduction cross sections. We will emphasize how this experiment provided the first stringent tests of the scaling property of this process, allowing for the first time a model-independent extraction of a linear combination of Generalized Parton Distributions. We will also describe the Hall B E01-113 experiment which measured the photon electroproduction beam spin asymmetry over a wide kinematical range. The summary will include an outlook on the next generation of experiments which are already planned at Jefferson Lab at 6 GeV, but also after the planned 12 GeV upgrade.

Franck Sabatie

2006-10-02

176

TeV Gamma-Ray Observations of Compton Gamma-Ray Observatory Pulsars: Evidence against Inverse-Compton Controlled Outer Gaps  

Microsoft Academic Search

We present the first results of TeV gamma-ray observations of the Compton Gamma-Ray Observatory gamma-ray pulsar PSR 1706-44, indicating a spectral cutoff between ˜20 GeV and 600 GeV. Improved upper limits are also presented for the Vela pulsar and PSR 1509-58. These and other TeV results confirm similar cutoffs for these gamma-ray pulsars as well as for Geminga. The polar

H. I. Nel; O. C. de Jager; B. C. Raubenheimer; C. Brink; P. J. Meintjes; A. R. North

1993-01-01

177

Energy calibration of plastic scintillators for low energy electrons by using Compton scatterings of ? rays  

Microsoft Academic Search

An energy calibration of plastic scintillators for electrons in the energy region 0.5–3MeV is shown to be made by means of Compton scatterings of ?-rays. The shape of the Compton spectrum was analytically derived and the availability of the shape function was tested by fitting the simulated spectrum. The method to derive the energy and energy resolution at the Compton

N. Kudomi

1999-01-01

178

Precision 0.5 GW X-band rf system for advanced Compton scattering source  

NASA Astrophysics Data System (ADS)

A Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering light source is being developed at LLNL. The electron beam for the Compton scattering interaction will be generated by a X-band RF gun and a X-band LINAC at the frequency of 11.424 GHz. High power RF in excess of 500 MW is needed to accelerate the electrons to energy of 250 MeV or greater for the interaction. Two high power klystron amplifiers, each capable of generating 50 MW, 1.5 msec pulses, will be the main high power RF sources for the system. These klystrons will be powered by state of the art solid-state high voltage modulators. A RF pulse compressor, similar to the SLED II pulse compressor, will compress the klystron output pulse with a power gain factor of five. This will give us 500 MW (0.5 GW) at output of the compressor. The compressed pulse will then be distributed to the RF gun and to the LINAC with specific phase and amplitude control points to allow for parameter control during operation. This high power RF system is being designed and constructed. In this paper, we will present the design, layout, and status of this RF system.

Chu, T. S.; Anderson, G.; Gibson, D.; Hartemann, F. V.; Barty, C. P. J.; Vlieks, A.; Tantawi, S.; Jongewaard, E.; Anderson, S. G.

2009-11-01

179

Fast analytical modeling of compton scatter using point clouds and graphics processing unit (GPU)  

Microsoft Academic Search

Quantitative SPECT and PET is not possible without accurate modeling of Compton scatter. The physics of this interaction is well-understood and Monte Carlo and analytical calculations are possible. However, such approaches require exorbitant computing times that limit their practical value in the clinical setting. We present a novel computational model that considerably reduces the computation time needed to estimate Compton

A. Sitek; G. El Fakhri; Jinsong Ouyang; J. S. Maltz

2007-01-01

180

Deeply virtual Compton scattering with CLAS and CLAS12  

SciTech Connect

Generalised Parton Distributions (GPDs) offer an insight into the three-dimensional structure of the nucleon and its internal dynamics, relating the transverse position of quarks to their longitudinal momentum. Two effective means of accessing GPDs are Deeply Virtual Compton Scattering (DVCS) and Meson Production (DVMP), in which a high energy electron scatters from a single quark in the nucleon and, respectively, a real photon or meson is produced as a result. Jefferson Laboratory (JLab), USA, is ideally suited for measuring these processes and a very active experimental programme has been underway in the recent years, making use of the lab's continuous electron beam up to 6 GeV in energy and its large angle spectrometer CLAS. In the future, a vast, new, as-yet unprobed kinematic region will become experimentally accessible when the current upgrade of the JLab accelerator to operate at a maximum energy of 12 GeV is completed in a few years. It is being complemented by the construction of a new suite of detectors, CLAS12, a number of them optimised specifically for exclusive reconstruction of DVCS and DVMP in the new kinematic region. We present a selection of recent results of DVCS and DVMP measurements using CLAS and introduce the exciting experimental programme planned for the future with CLAS12.

Sokhan, Daria [Institut de Physique Nucleaire, Orsay, France

2012-06-01

181

Apparatus Subtraction of Compton Distribution in a High Resolution Gamma Spectrometer.  

National Technical Information Service (NTIS)

A possibility of suppressing the Compton background in the apparatus spectra of gamma radiation is considered. It is achieved due to the flattening of the total absorption peaks by means of a special apparatus perturbation and subtraction of the flattened...

A. I. Gonchar L. P. Kham'yanov B. V. Nesterov

1974-01-01

182

A Combined Compton and Coded Mask Telescope for Gamma-Ray Astrophysics  

NASA Astrophysics Data System (ADS)

In order to improve upon past and current observations in medium-energy gamma-ray astrophysics (Comptel, Integral/SPI), a next generation telescope must have good energy resolution to allow for accurate nuclear line shape analysis and high angular resolution to allow for resolving and locating point sources as well as diffuse emission. Additionally, a large effective area and background rejection capabilities are needed in order to achieve a high sensitivity. To address these requirements, we are investigating the potential of combining the background rejection capabilities and thus high sensitivity of a Compton telescope with the good angular resolution that can be achieved using a coded mask. We present a preliminary study of a combined telescope that utilizes an array of double-sided Silicon strip detectors as a Compton scatter plane and cubic-centimeter Cadmium Zinc Telluride (CdZnTe) semiconductor detectors as an absorption plane. The Silicon detector performance is based upon a study for the Gamma-Ray burst Investigation via Polarimetry and Spectroscopy (GRIPS) telescope. The CdZnTe detector response is based upon benchmarked laboratory measurements using 1-cm3 CdZnTe coplanar-grid detectors. The Compton telescope is combined with a partially filled coded mask with a 10° field-of-view. A series of monoenergetic line sources from 200 keV to 6.1 MeV have been simulated, as well as a 511 keV broadened source and a Crab-like continuum. The telescope has achievable energy resolutions of 1.68% FWHM at 511 keV and 1.11% at 1809 keV, on-axis angular resolutions in Compton mode of 2.63° ± FWHM at 511 keV and 1.30° ± FWHM at 1809 keV, and is capable of resolving sources to at least 0.2° using the coded mask. An initial assessment of the instrument yields an anticipated all-sky sensitivity of 3.6 x 10-6 photons cm-2 s-1 for a broadened 511 keV source over a 2 year observation time. These capabilities meet several scientific objectives in medium-energy gamma-ray astronomy, such as achieving the sensitivity and accuracy required for nuclear line studies and allowing for an improved assessment of the spatial distribution of Galactic 511 keV emission.

Galloway, Michelle; Zoglauer, A.; Boggs, S. E.; Amman, M.

2013-04-01

183

Optimizing a three-stage Compton camera for measuring prompt gamma rays emitted during proton radiotherapy  

PubMed Central

In this work, we investigate the use of a three-stage Compton camera to measure secondary prompt gamma rays emitted from patients treated with proton beam radiotherapy. The purpose of this study was (1) to develop an optimal three-stage Compton camera specifically designed to measure prompt gamma rays emitted from tissue and (2) to determine the feasibility of using this optimized Compton camera design to measure and image prompt gamma rays emitted during proton beam irradiation. The three-stage Compton camera was modeled in Geant4 as three high-purity germanium detector stages arranged in parallel-plane geometry. Initially, an isotropic gamma source ranging from 0 to 15 MeV was used to determine lateral width and thickness of the detector stages that provided the optimal detection efficiency. Then, the gamma source was replaced by a proton beam irradiating a tissue phantom to calculate the overall efficiency of the optimized camera for detecting emitted prompt gammas. The overall calculated efficiencies varied from ~10?6 to 10?3 prompt gammas detected per proton incident on the tissue phantom for several variations of the optimal camera design studied. Based on the overall efficiency results, we believe it feasible that a three-stage Compton camera could detect a sufficient number of prompt gammas to allow measurement and imaging of prompt gamma emission during proton radiotherapy.

Peterson, S W; Robertson, D; Polf, J

2011-01-01

184

Optimal Sum Rules Inequalities for Spin 1/2 Compton Scattering.  

National Technical Information Service (NTIS)

A formalism appropriate for model independent dispersion theoretic investigations of the (not necessarily forward) Compton scattering off spin 1/2 hadronic targets, which fully exploits the analyticity properties of the amplitudes (to lowest order in elec...

I. Guiasu E. E. Radescu I. Razillier

1979-01-01

185

Optimal Sum-Rule Inequalities for Spin 1/2 Compton Scattering. III.  

National Technical Information Service (NTIS)

The analyticity (optimal) bounds for proton Compton scattering presented in the preceding paper are herewith considered from the point of view of experimental tests. An essential function occuring in this new dispersion framework is constructed numericall...

L. V. Filkov I. Guiasu D. Pantea E. E. Radescu

1980-01-01

186

Observation of sub-MeV gamma rays with an Electron Tracking Compton Telescope using a gaseous TPC at balloon altitudes  

NASA Astrophysics Data System (ADS)

Observations in the low-energy gamma-ray band from hundreds of keV to tens of MeV provide the information of the nucleosynthesis, ultra-hot plasma around a black hole, the particle acceleration and the interaction of cosmic-ray and interstellar matter. However, observation in this energy band is very difficult because the dominant process in a detector is Compton scattering, and then suffers from large backgrounds of photons are produced in the hadronic process between cosmic rays and a satellite body. Therefore, MeV gamma-ray astronomy has not advanced in comparison with X-ray or other gamma-ray bands. For a MeV gamma-ray telescope in the next generation, we hence developed an electron-tracking Compton camera (ETCC) consisting of a three-dimensional gaseous tracker of Compton-recoil electrons and an absorber of Compton-scattered gamma rays using a new detection method with powerful background rejection. Because the camera obtains the energy and the direction of both the scattered gamma-ray and the recoil electron, the ETCC can restrict the incident direction of a gamma ray to a reduced arc on the Compton circle and determines the energy of the incident gamma ray, photon by photon. Moreover, the angle between the direction of the scattered gamma ray and that of the Compton-recoil electron can be used for powerful background rejection by checking the consistency between the measured and kinematically calculated values. We had already confirmed the detection principle of the ETCC by ground-based experiments, and thus have begun the observation of celestial sub-MeV gamma rays with a balloon-borne camera, the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment (SMILE), since 2006. As the first flight of SMILE, in oder to study background gamma rays for observing celestial objects and verify the background rejection capability, we observed diffuse cosmic gamma rays and atmospheric gamma rays using a small ETCC of a 10x10x15 cm3 detection area, which are generated by interaction between cosmic-ray particles and nuclei in the atmosphere at an altitude of up to approximately 35 km. In this paper, we report the observation results of the first flight of SMILE and the preparations for the next flight using a larger detector.

Takada, Atsushi; Tanimori, Toru; Kubo, Hidetoshi; Miuchi, Kentaro; Kabuki, Shigeto; Parker, Joseph; Nishimura, Hironobu; Hattori, Kaori; Ueno, Kazuki; Kurosawa, Shunsuke; Iwaki, Satoru; Ida, Chiriro; Takahashi, Michiaki; Sawano, Tatsuya; Taniue, Kojiro; Nakamura, Kiseki; Higashi, Naoki

187

Collision Integral Cross Sections in Double Photon Compton Scattering and a Possible Method for Their Measurement  

SciTech Connect

The collision integral cross sections are obtained and computed for several experimentally realizable cases to understand the various features of the higher-order process known as double photon Compton scattering. The computational work carried out using the Mathematica software package generally corresponds to three different incident gamma photon energies of {sup 137}Cs (661.65 keV), {sup 65}Zn (1.12 MeV), and that from the radiative capture of {sup 19}F (6.14 MeV). The characteristic features revealed a need to be investigated experimentally to check for their support to the currently acceptable theory of this quantum electrodynamics process. An experimental technique has been suggested for the measurement of these collision integral cross sections.

Sharma, Aarti; Saddi, M.B.; Singh, B.; Sandhu, B.S. [Punjabi University (India)

2004-11-15

188

Autoionization emission for x-ray-excited Auger spectra in the Compton-scattering process  

SciTech Connect

Autoionization emission in the 3d transition-metal series is observed for the x-ray-excited Auger electrons in the Compton-scattering process. Kinematical analysis of Compton scattering shows that such emission becomes possible only when the x rays have sufficiently high energy to lift the bound 3p electrons into the conduction band. With the tuning capabilities of synchrotron sources, this should open a new channel in autoionization experiments.

Brener, R.; Felsteiner, J.; Tyk, R.; Zak, J.

1988-01-15

189

Polarisation Observables in Wide-angle Compton Scattering from the Proton  

Microsoft Academic Search

The Jefferson Lab Hall A experiment E99-114 comprised a series of measurements to explore wide-angle Compton scattering from the proton. For the first time, the double polarisation observables for Compton scattering were measured in the GeV energy range, where it is believed that quark-gluon degrees of freedom begin to dominate. A polarised photon beam was incident on a liquid hydrogen

D. J. Hamilton

2003-01-01

190

Inverse Compton Scattering on Solar Photons, Heliospheric Modulation, and Neutrino Astrophysics  

SciTech Connect

We study the inverse Compton scattering of solar photons by Galactic cosmic-ray electrons. We show that the {gamma}-ray emission from this process is significant with the maximum flux in the direction of the Sun; the angular distribution of the emission is broad. This previously neglected foreground should be taken into account in studies of the diffuse Galactic and extragalactic {gamma}-ray emission. Furthermore, observations by GLAST can be used to monitor the heliosphere and determine the electron spectrum as a function of position from distances as large as Saturn's orbit down to close proximity of the Sun, thus enabling studies of solar modulation in the most extreme case. This paves the way for the determination of other Galactic cosmic-ray species, primarily protons, near the solar surface leading to accurate predictions of {gamma}-rays from pp-interactions in the solar atmosphere. These albedo {gamma}-rays will be observable by GLAST, allowing the study of deep atmospheric layers, magnetic field(s), and cosmic-ray cascade development. The latter is necessary to calculate the neutrino flux from pp-interactions at higher energies (>1 TeV). The corresponding neutrino flux from the Sun can be used as a ''standard candle'' for upcoming km{sup 3} neutrino detectors, such as IceCube. Since the solar core is opaque for very high-energy neutrinos, it may be possible to directly study the mass distribution of the Sun.

Moskalenko, Igor V.; /Stanford U., HEPL; Porter, Troy A.; /UC, Santa Cruz; Digel, Seth W.; /SLAC

2006-08-01

191

Proton Compton Scattering and Pion-Production with Polarized Photons  

NASA Astrophysics Data System (ADS)

In analogy to the N-N tensor force in deuteron deformation, a tensor interaction, motivated by one-gluon exchange, between quarks introduces a D state component into the nucleon wave function. The experimental signature of such a quadrupole moment lies in the nucleon's first excited state, the Delta resonance which is photo-excited mainly by M1 photons. However, the D-wave component results in a small E2 transition strength which is quite sensitive to the internal structure of the proton. Since the tensor interaction mixes quark spins with their relative motion, polarization observables can be used to enhance the interference effects that are largely hidden in spin-averaged unpolarized measurements. The p(vec{gamma}, gamma p) and p(vec{gamma }, pi^circ) reactions were studied with linearly polarized gamma -rays between 210 and 330 MeV from the Laser Electron Gamma Source (LEGS) facility at Brookhaven National Laboratory. The two reaction channels were separated by detecting both scattered photons and recoil protons. The beam energy was tagged so that the energy dependent systematic errors were greatly reduced. Data for three sets of center of mass (CM) angle measurements, 60^circ, 90^ circ and 120^circ, are presented in terms of 12 energy bins (+/- 5 MeV). Results are at least in fair agreement comparing with selected model calculations. The measured polarization observables can be used for a new multipole analysis that will serve as a further constraint to the various theoretical models.

Zhang, Hong

1995-01-01

192

Theoretical Description of Deeply Virtual Compton Scattering off 3He  

NASA Astrophysics Data System (ADS)

Recently, coherent deeply virtual Compton scattering (DVCS) off 3He nuclei has been proposed to access the neutron generalized parton distributions (GPDs). In impulse approximation (IA) studies, it has been shown, in particular, that the sum of the two leading twist, quark helicity conserving GPDs of 3He, H and E, at low momentum transfer, is dominated by the neutron contribution, so that 3He is very promising for the extraction of the neutron information. Nevertheless, such an extraction could be not trivial. A technique, able to take into account the nuclear effects included in the IA analysis in the extraction procedure, has been therefore developed. In this work, the IA calculation of the spin dependent GPD {tilde H} of 3He is presented for the first time. This quantity is found to be largely dominated, at low momentum transfer, by the neutron contribution, which could be extracted using arguments similar to the ones previously proposed for the other GPDs. The known forward limit of the IA calculation of {tilde H} , yielding the polarized parton distributions of 3He, is correctly recovered. The knowledge of the GPDs H, E and {tilde H} of 3He will allow now the evaluation of the cross section asymmetries which are relevant for coherent DVCS off 3He at Jefferson Lab kinematics, an important step towards the planning of possible experiments.

Rinaldi, M.; Scopetta, S.

2014-01-01

193

Thick silicon strip detector Compton imager  

Microsoft Academic Search

We present results obtained with double-sided, thick (2 mm) silicon strip detectors used as a Compton imager. Reconstructed images and spectra from 137Cs and 60Co gamma-ray sources have been produced at room temperature using the multiple Compton technique. Multiple Compton interactions allow the energy and Compton scattering angle to be reconstructed without having to absorb the energy of the incident

Eric A. Wulf; Bernard F. Phlips; W. Neil Johnson; James D. Kurfess; Elena I. Novikova

2004-01-01

194

Development of compact coherent EUV source based on laser Compton scattering  

NASA Astrophysics Data System (ADS)

High-power extreme ultra-violet (EUV) sources are required for next generation semiconductor lithography. We start to develop a compact EUV source in the spectral range 13-14 nm, which is based on a laser Compton scattering between a 7 MeV micro-bucnhed electron beam and a high-intensity CO 2 laser pulse. The electron beam extracted from a DC photocathode gun is micro-bunched using a laser modulation techinque with the Compton wavelength at a harmonic of the seeding laser before the main laser Compton scattering for EUV generation. A considerating scheme for the compact EUV source based on the laser Compton scattering with micro-bunched electron beam and the analytical study of micro-bunch generation are described in this paper.

Kashiwagi, S.; Kato, R.; Isoyama, G.; Sakaue, K.; Masuda, A.; Nomoto, T.; Gowa, T.; Washio, M.; Kuroda, R.; Urakawa, J.

2009-12-01

195

Calibration and performance of the UCR double Compton gamma ray telescope  

NASA Technical Reports Server (NTRS)

Results of the field calibration and performance of the UCR double Compton gamma-ray telescope are presented. The telescope is a balloon-borne instrument with an upper array of 16 plastic scintillator bars and a lower one of 16 NaI(Tl) bars. The telescope is sensitive to celestial gamma rays from 1 to 30 MeV. The data were collected on February 14, 1988 prior to launch in Alice Springs, Australia to observe SN 1987A. Radioactive sources were used to calibrate the energy deposits in the scintillators. Each bar was analyzed laterally using pulse height or timing to obtain the positions of the gamma ray interactions. Double scatter events from an Na-24 source simulating a celestial source were studied to obtain the general performance of the telescope and to develop imaging techniques, later used with the flight data. An angular resolution of 11 deg FWHM and energy resolutions of 13 and 10 percent FWHM at 1.37 and 2.75 MeV, respectively, were found. The efficiency of the telescope is 0.0035 at 1.37 MeV and zenith angle 31 deg.

Ait-Ouamer, Farid; Kerrick, Alan D.; Sarmouk, Abderrezak; O'Neill, Terrence J.; Sweeney, William E.

1990-01-01

196

Si/CdTe Compton Telescope combined with Active Collimator as the Soft Gamma-ray Detector for the 'NeXT' mission  

NASA Astrophysics Data System (ADS)

The Soft Gamma-ray Detector (SGD) is a new generation compton telescope aiming at an order of magnitude improvement of sensitivity at the energy band of 80-1000 keV. The SGD is proposed to be launched at 2010-11, onboard the Japanese new astronomy satellite ``NeXT." Novel idea of the SGD is to use a Si/CdTe semiconductor multi-layer compton telescope within the low background environment achieved by the deep active shield with a narrow opening angle. Because compton telescope hosts an imaging capability, any residual backgrounds, such as the activation of the main detector itself, can by rejected by requiring the compton scattering angle to be consistent with the opening angle of the shield, which is about 4 degree with current design. The key technologies of the SGD are the deep active shield which is a direct heritage of the Hard X-ray Detector onboard Astro-E2 mission, and the newly developed Si/CdTe compton telescope. Current design of the Si/CdTe compton telescope consists of 24 layers of 0.5 mm thick double-sided-silicon-strip-detector (DSSD) as a scatterer, surrounded by thin and thick CdTe pixel detectors with a total thickness of 5 mm as an absorber. The design is optimized for detecting gamma-rays at about 100-700 keV when operated at compton mode. We present the results from the first prototype of Si/CdTe compton telescope, made of a 300 um thick DSSD and 0.5 mm thick CdTe pixel detectors. We also present the estimated performance of the SGD with current design, and possible improvements in the future.

Kazuhiro, N.; Tadayuki, T.; Shin, W.; Tune, K.; Greg, M.; Hiroyasu, T.; Yasushi, F.; Masaharu, N.; Motohide, K.; Kazuo, M.; Makoto, T.; Yukikatsu, T.; Jun, K.; NeXT SGD Collaboration

2004-08-01

197

Observation of diffuse gamma-ray with Electron-Tracking Compton imaging camera loaded on balloon  

Microsoft Academic Search

We have developed an electron tracking Compton camera (ETCC) as an MeV gamma-ray telescope in the next generation. Our detector consists of a gaseous time projection chamber and a position sensitive scintillation camera. In order to evaluate the performance of this detector, we constructed a flight model detector as a balloon experiment for the observation of diffuse cosmic gamma rays

A. Takada; T. Tanimori; H. Kubo; K. Miuchi; K. Tsuchiya; S. Kabuki; H. Nishimura; K. Hattori; K. Ueno; S. Kurosawa; N. Nonaka; E. Mizuta; R. Orito; T. Nagayoshi

2007-01-01

198

The Development of High-Resolution Calorimetric X-Ray Detectors for Compton Scattering Experiments  

Microsoft Academic Search

Compton scattering is a means of probing electron momentum distributions and can be used to evaluate calculations of electron wavefunctions in solids. The need for improved resolution in Compton experiments performed with high energy x-rays has motivated the development of a high resolution spectrometer. Calorimetric x-ray detectors, produced at Goddard Space Flight Center for x-rays around 6 KeV, have been

Caroline Kilbourne Stahle

1992-01-01

199

Design Study of Laser Compton Scattering with Relativistic Electron to Measure the Electron Beam Energy  

Microsoft Academic Search

This paper presents the design study of a system to measure the electron beam energy in an accelerator. The method of Compton scattering between laser photons and relativistic electrons was used. The optical system for the laser light was design to match the laser beam with the electron beam in order to enhance the back scattered photon flux. .4 simulation

Ian Hsu; H. Chen; C. Cho; Y. Liu

1994-01-01

200

Exclusive Vector Meson Production and Deep Virtual Compton Scattering in Electron-Ion Collisions  

SciTech Connect

We calculate the nuclear cross section for coherent and incoherent deep virtual Compton scattering as well as for coherent and incoherent vector meson production for the mesons J/{Psi}, {phi} and {rho} within the QCD color dipole picture, including saturation effects. Theoretical estimates for scattering on both light and heavy nuclei are given over a wide range of energy.

Cazaroto, E. R.; Navarra, F. S. [Instituto de Fisica, Universidade de Sao Paulo, C.P 66318, 05389-970 Sao Paulo, SP (Brazil); Carvalho, F. [Depto de ciencias exatas e da terra, Universidade Federal de Sao Paulo, Sao Paulo, SP (Brazil); Kugeratski, M. S. [Universidade Federal de Santa Catarina, Curitibanos, SC (Brazil); Goncalves, V. P. [Instituto de Fisica e Matematica, Universidade Federal de Pelotas, Pelotas, RS (Brazil)

2010-11-12

201

Virtual Compton scattering and neutral pion electroproduction in the resonance region up to the deep inelastic region at backward angles  

SciTech Connect

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e, e{sup '}p){gamma} exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q{sup 2}=1 GeV{sup 2} and for the Q{sup 2} dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q{sup 2} dependence is smooth. The measured ratio of H(e, e{sup '}p){gamma} to H(e, e{sup '}p){pi}{sup 0} cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to real Compton scattering (RCS) at high energy and large angles, our VCS data at the highest W (1.8-1.9 GeV) show a striking Q{sup 2} independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.

Laveissiere, G.; Jaminion, S.; Salvo, R. Di; Berthot, J.; Bertin, P. Y.; Breton, V.; Fonvieille, H.; Grenier, P.; Ravel, O.; Roblin, Y.; Smirnov, G. [LPC-Clermont, Universite Blaise Pascal, CNRS/IN2P3, F-63177 Aubiere Cedex (France); Degrande, N.; Hoorebeke, L. van; Vyver, R. van de [University of Gent, B-9000 Gent (Belgium); Jutier, C.; Hyde, C. E. [LPC-Clermont, Universite Blaise Pascal, CNRS/IN2P3, F-63177 Aubiere Cedex (France); Old Dominion University, Norfolk, Virginia 23529 (United States); Todor, L.; Dodge, G. E.; McCormick, K.; Ulmer, P. E. [Old Dominion University, Norfolk, Virginia 23529 (United States)] (and others)

2009-01-15

202

Triple coincidence beam spin asymmetry measurements in Deeply Virtual Compton Scattering  

NASA Astrophysics Data System (ADS)

The Generalized Parton Distributions (GPDs) provides hitherto the most complete information about the quark structure of hadron. GPDs are accessible through hard-exclusive reactions, among which Deeply Virtual Compton Scattering (DVCS) is the cleanest reaction. A dedicated DVCS experiment on Hydrogen (E00-110) ran in the Hall A at Jefferson Laboratory in Fall 2004. I present here Beam Spin Asymmetry (BSA) results for the ep ? epgamma reaction studied in the E00-110 experiment with fully exclusive triple coincidence H(e, e'gammap ) detection. I present a re-calibration of the electromagnetic calorimeter used to detect the high energy photon. This calibration is necessary to account for the effects of pile-up. The results show a 1-sigma disagreement with the double coincidence H(e, e'gamma )p results, I also presents a feasibility study for measurements of neutron GPDs via the 3He ? (e, e'gamma)ppn reaction on a polarized 3He target with JLab at 12 GeV. These measurements offer the prospect of a determination of all four GPDs.

Canan, Mustafa

203

Magnetic Compton Scattering Studies of the INVAR Effect in IRON(2) Platinum  

NASA Astrophysics Data System (ADS)

Magnetic Compton scattering (MCS) was used to study the magnetic state of Fe_3Pt at temperatures above and below its critical temperature. As Fe_3Pt is an Invar alloy, it has found widespread commercial use, and thus, it is interesting to study. While the mechanism behind the temperature independent elastic behavior (the "Invar effect") has never been shown, recent experiments have caused most theories to be put aside in favor of the phenomenological Weiss 2 ^{gamma} model. This model claims that the source of the Invar effect is a change in the magnetic state of the alloy. This change is examined by inelastically scattering circularly polarized photons from Fe_3Pt at temperatures above and below its Curie temperature. The result is the momentum distribution of the unpaired (or magnetic) electrons in the alloy. From this, the mechanism behind the Invar effect is inferred to be a substantial decrease of the magnetic moment of the 3d states on the Fe atoms. MCS experiments require a source of circularly polarized x-rays. Unfortunately, such sources are not readily available. Therefore, to accomodate our source requirements, an x-ray phase plate made of single crystal germanium was constructed. It was designed to operate at discrete energies over the range 20-88 keV and found to produce a degree of circular polarization of 90% at 65 keV.

Yahnke, Clifford James

1995-01-01

204

Test of Compton camera components for prompt gamma imaging at the ELBE bremsstrahlung beam  

NASA Astrophysics Data System (ADS)

In the context of ion beam therapy, particle range verification is a major challenge for the quality assurance of the treatment. One approach is the measurement of the prompt gamma rays resulting from the tissue irradiation. A Compton camera based on several position sensitive gamma ray detectors, together with an imaging algorithm, is expected to reconstruct the prompt gamma ray emission density map, which is correlated with the dose distribution. At OncoRay and Helmholtz-Zentrum Dresden-Rossendorf (HZDR), a Compton camera setup is being developed consisting of two scatter planes: two CdZnTe (CZT) cross strip detectors, and an absorber consisting of one Lu2SiO5 (LSO) block detector. The data acquisition is based on VME electronics and handled by software developed on the ROOT framework. The setup has been tested at the linear electron accelerator ELBE at HZDR, which is used in this experiment to produce bunched bremsstrahlung photons with up to 12.5 MeV energy and a repetition rate of 13 MHz. Their spectrum has similarities with the shape expected from prompt gamma rays in the clinical environment, and the flux is also bunched with the accelerator frequency. The charge sharing effect of the CZT detector is studied qualitatively for different energy ranges. The LSO detector pixel discrimination resolution is analyzed and it shows a trend to improve for high energy depositions. The time correlation between the pulsed prompt photons and the measured detector signals, to be used for background suppression, exhibits a time resolution of 3 ns FWHM for the CZT detector and of 2 ns for the LSO detector. A time walk correction and pixel-wise calibration is applied for the LSO detector, whose resolution improves up to 630 ps. In conclusion, the detector setup is suitable for time-resolved background suppression in pulsed clinical particle accelerators. Ongoing tasks are the quantitative comparison with simulations and the test of imaging algorithms. Experiments at proton accelerators have also been performed and are currently under analysis.

Hueso-González, F.; Golnik, C.; Berthel, M.; Dreyer, A.; Enghardt, W.; Fiedler, F.; Heidel, K.; Kormoll, T.; Rohling, H.; Schöne, S.; Schwengner, R.; Wagner, A.; Pausch, G.

2014-05-01

205

Compton DIV: Using a Compton-Based Gamma-Ray Imager for Design Information Verification of Uranium Enrichment Plants  

SciTech Connect

A feasibility study has been performed to determine the potential usefulness of Compton imaging as a tool for design information verification (DIV) of uranium enrichment plants. Compton imaging is a method of gamma-ray imaging capable of imaging with a 360-degree field of view over a broad range of energies. These systems can image a room (with a time span on the order of one hour) and return a picture of the distribution and composition of radioactive material in that room. The effectiveness of Compton imaging depends on the sensitivity and resolution of the instrument as well the strength and energy of the radioactive material to be imaged. This study combined measurements and simulations to examine the specific issue of UF{sub 6} gas flow in pipes, at various enrichment levels, as well as hold-up resulting from the accumulation of enriched material in those pipes. It was found that current generation imagers could image pipes carrying UF{sub 6} in less than one hour at moderate to high enrichment. Pipes with low enriched gas would require more time. It was also found that hold-up was more amenable to this technique and could be imaged in gram quantities in a fraction of an hour. another questions arises regarding the ability to separately image two pipes spaced closely together. This depends on the capabilities of the instrument in question. These results are described in detail. In addition, suggestions are given as to how to develop Compton imaging as a tool for DIV.

Burks, M; Verbeke, J; Dougan, A; Wang, T; Decman, D

2009-07-04

206

Quality Control of Pavements and Tarmacs Using (137Cs) ? Compton Scattering  

NASA Astrophysics Data System (ADS)

The ? Compton scattering over a volume of concrete has been studied in order to design an instrument for density measurements. It will be used for the quality control in road construction, where large surfaces must be monitored. The experimental results and Monte Carlo simulations of the ? Compton scattering over homogeneous and inhomogeneous volumes of concrete are shown. MC simulations have been useful to optimize the values of several parameters to improve the experimental set up and to estimate the extension of the explored volume.

Pino, F.; Barros, H.; Bernal, M.; Sajo-Bohus, L.; Palacios, D.; Greaves, E. D.; Viesti, G.

2010-08-01

207

Intercomparison of gamma ray scattering and transmission techniques for gas volume fraction measurements in two phase pipe flow  

NASA Astrophysics Data System (ADS)

Void fraction simulating stratified air-water flow in cylindrical tubes of different radii was measured using transmission and scattering of gamma rays. A simple experimental set-up using 137Cs ?-ray point source of 10 ?Ci and NaI(Tl) detector was used. The void fractions determined from Compton-Compton scattering and transmission peaks were found in good agreement with the real void fractions. However, deviations were noticed between the results obtained from traditional Compton scattered gamma rays and real void fraction. It was shown that sensitivity of gamma ray scattering is better than the transmission measurements. The set-up used in the present work is simpler than those existing in literature and radiation safety and shielding requirements are minimized.

El Abd, A.

2014-01-01

208

Observation of Diffuse Cosmic and Atmospheric Gamma Rays at Balloon Altitudes with an Electron-tracking Compton Camera  

NASA Astrophysics Data System (ADS)

We observed diffuse cosmic and atmospheric gamma rays at balloon altitudes with the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I (SMILE-I) as the first step toward a future all-sky survey with a high sensitivity. SMILE-I employed an electron-tracking Compton camera comprised of a gaseous electron tracker as a Compton-scattering target and a scintillation camera as an absorber. The balloon carrying the SMILE-I detector was launched from the Sanriku Balloon Center of the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency on 2006 September 1, and the flight lasted for 6.8 hr, including level flight for 4.1 hr at an altitude of 32-35 km. During the level flight, we successfully detected 420 downward gamma rays between 100 keV and 1 MeV at zenith angles below 60°. To obtain the flux of diffuse cosmic gamma rays, we first simulated their scattering in the atmosphere using Geant4, and for gamma rays detected at an atmospheric depth of 7.0 g cm-2 we found that 50% and 21% of the gamma rays at energies of 150 keV and 1 MeV, respectively, were scattered in the atmosphere prior to reaching the detector. Moreover, by using Geant4 simulations and the QinetiQ atmospheric radiation model, we estimated that the detected events consisted of diffuse cosmic and atmospheric gamma rays (79%), secondary photons produced in the instrument through the interaction between cosmic rays and materials surrounding the detector (19%), and other particles (2%). The obtained growth curve was comparable to Ling's model, and the fluxes of diffuse cosmic and atmospheric gamma rays were consistent with the results of previous experiments. The expected detection sensitivity of a future SMILE experiment measuring gamma rays between 150 keV and 20 MeV was estimated from our SMILE-I results and was found to be 10 times better than that of other experiments at around 1 MeV.

Takada, Atsushi; Kubo, Hidetoshi; Nishimura, Hironobu; Ueno, Kazuki; Hattori, Kaori; Kabuki, Shigeto; Kurosawa, Shunsuke; Miuchi, Kentaro; Mizuta, Eiichi; Nagayoshi, Tsutomu; Nonaka, Naoki; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki; Takeda, Atsushi; Tanimori, Toru

2011-05-01

209

OBSERVATION OF DIFFUSE COSMIC AND ATMOSPHERIC GAMMA RAYS AT BALLOON ALTITUDES WITH AN ELECTRON-TRACKING COMPTON CAMERA  

SciTech Connect

We observed diffuse cosmic and atmospheric gamma rays at balloon altitudes with the Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment I (SMILE-I) as the first step toward a future all-sky survey with a high sensitivity. SMILE-I employed an electron-tracking Compton camera comprised of a gaseous electron tracker as a Compton-scattering target and a scintillation camera as an absorber. The balloon carrying the SMILE-I detector was launched from the Sanriku Balloon Center of the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency on 2006 September 1, and the flight lasted for 6.8 hr, including level flight for 4.1 hr at an altitude of 32-35 km. During the level flight, we successfully detected 420 downward gamma rays between 100 keV and 1 MeV at zenith angles below 60 deg. To obtain the flux of diffuse cosmic gamma rays, we first simulated their scattering in the atmosphere using Geant4, and for gamma rays detected at an atmospheric depth of 7.0 g cm{sup -2} we found that 50% and 21% of the gamma rays at energies of 150 keV and 1 MeV, respectively, were scattered in the atmosphere prior to reaching the detector. Moreover, by using Geant4 simulations and the QinetiQ atmospheric radiation model, we estimated that the detected events consisted of diffuse cosmic and atmospheric gamma rays (79%), secondary photons produced in the instrument through the interaction between cosmic rays and materials surrounding the detector (19%), and other particles (2%). The obtained growth curve was comparable to Ling's model, and the fluxes of diffuse cosmic and atmospheric gamma rays were consistent with the results of previous experiments. The expected detection sensitivity of a future SMILE experiment measuring gamma rays between 150 keV and 20 MeV was estimated from our SMILE-I results and was found to be 10 times better than that of other experiments at around 1 MeV.

Takada, Atsushi; Nonaka, Naoki [Research and Operation Office for Scientific Ballooning, ISAS, JAXA, Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Kubo, Hidetoshi; Nishimura, Hironobu; Ueno, Kazuki; Hattori, Kaori; Kabuki, Shigeto; Kurosawa, Shunsuke; Miuchi, Kentaro; Nagayoshi, Tsutomu; Okada, Yoko; Orito, Reiko; Sekiya, Hiroyuki; Takeda, Atsushi; Tanimori, Toru [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Mizuta, Eiichi, E-mail: kubo@cr.scphys.kyoto-u.ac.jp [Electronic Components and Devices Group, ISAS, JAXA, Yoshinodai 3-1-1, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan)

2011-05-20

210

Optimal Sum-Rule Inequalities for Spin 1/2 Compton Scattering. II.  

National Technical Information Service (NTIS)

A new set of ''analytic unitary amplitudes'' (a.u.a.) for spin 1/2 hadron Compton scattering (i.e. s-u crossing symmetric amplitudes which for t in a specified range of physical values have the same good analyticity properties in nu exp 2 ( nu = (s-u)/4; ...

I. Guiasu E. E. Radescu

1980-01-01

211

An analytic reconstruction for the Compton scattering tomography in a plane  

NASA Astrophysics Data System (ADS)

In this paper, a new reconstruction formula is obtained for the plane Compton scattering tomography with the acquisition geometry proposed by Nguyen and Truong (2010 Inverse Problems http://dx.doi.org/10.1088/0266-5611/26/6/065005). Range conditions and estimates of the Sobolev norms are also stated.

Palamodov, V. P.

2011-12-01

212

Forward Compton Scattering Amplitude as a Simultaneous Analytic Function of Complex Photon Mass and Energy  

Microsoft Academic Search

The analytic structure of the virtual forward Compton scattering amplitude as a function of one and two complex variables is investigated for various combinations of variables which involve the virtual photon mass. This is done both by using the Deser-Gilbert-Sudarshan representation and by using the Feynman perturbation theory. The role and significance of complex Landau singularities is discussed. In general

Ashok Suri

1971-01-01

213

Designing and testing a compton converter of gamma radiation and x-rays to electric current  

Microsoft Academic Search

The design and testing of a Compton current generator are briefly described. Its current response to a ? quantum (i.e., sensitivity)\\u000a is estimated at ?=7.010?21 (A cm2 s)\\/?. At relatively high gamma fluxes, the generator can be employed as a battery charger. When it is fed by a pulsed gamma\\u000a flux, the resulting current pulse is capable of triggering the

V. N. Gryzun; G. G. Katraev; A. K. Chernyshev

2001-01-01

214

Global phase and frequency comb structures in nonlinear Compton and Thomson scattering  

NASA Astrophysics Data System (ADS)

The Compton and Thomson radiation spectra generated in collisions of an electron beam with a powerful laser beam are studied in the framework of quantum and classical electrodynamics, respectively. We show that there are frequency regimes where both radiation spectra are nearly identical, which for Compton scattering relates to the process which preserves the electron spin. Although the radiation spectra are nearly identical, the corresponding probability amplitudes exhibit different global phases. This has pronounced consequences, which we demonstrate by investigating temporal power distributions in both cases. We show that, contrary to Thomson scattering, it is not always possible to synthesize short laser pulses from Compton radiation. This happens when the global phase of the Compton amplitude varies in a nonlinear way with the frequency of emitted photons. We also demonstrate that, while the Compton process driven by a nonchirped laser pulse can generate chirped bursts of radiation, this is not the case for the Thomson process. In principle, both processes can lead to a generation of coherent frequency combs when single or multiple driving laser pulse collide with electrons. Once we synthesize these combs into short bursts of radiation, we can control them, for instance, by changing the time delay between the driving pulses.

Krajewska, K.; Twardy, M.; Kami?ski, J. Z.

2014-05-01

215

Precise tests of x-ray scattering theories in the Compton regime.  

SciTech Connect

The authors report two experiments intended to test the accuracy of state-of-the-art theoretical predictions for x-ray scattering from low-Z atoms. The first one deals with the differential x-ray scattering cross sections in Ne and He from 11-22 keV and the Ne Compton-to-Rayleigh scattering ratio in this energy range. It was found that, in order to be consistent with the experimental results, an accurate description at low Z must include nonlocal exchange, electron correlation, and dynamic effects. The second experiment concerns the ratio of helium double-to-single ionization for Compton scattering in the 8-28 keV energy range where published experimental and theoretical results so far fail to give a consistent picture. The progress of the experiment and the data analysis is reported.

Dunford, R. W.; Gemmell, D. S.; Kanter, E. P.; Krassig, B.; Southworth, S. H.; Young, L.

1999-01-15

216

A New 3He-Target Design for Compton Scattering Experiment  

NASA Astrophysics Data System (ADS)

The neutron spin polarizabilities describe the stiffness of the neutron spin to external electric and magnetic fields. A double-polarized elastic Compton Scattering experiment will try to determine the neutron spin polarizabilities using a new polarized ^3He target and the circularly polarized ?-beam of HI?S facility at the Duke Free Electron Laser Laboratory (DFELL). To polarize the ^3He target, a newly constructed solenoid is being used which can provide a very uniform magnetic field around the target area and allows to place High Intensity Gamma Source NaI Detector Arrays (HINDA) closer to the target. The ideal target polarization is 40-60% and will be measured using the nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR) techniques. A prototype of the polarized ^3He target is being constructed in the Medium Energy Physics Group laboratories at Duke and is currently being tested. The experiment is expected to take place in 2013 after the DFELL upgrade. I will be presenting details of the construction process, including design specifications and data from the magnetic field mapping, as well as preliminary target polarization results. This work is supported by the US Department of Energy, under contract number DE-FG02-03ER41231, and by the National Science Foundation, grant number NSF-PHY-08-51813.

Mahalchick, S.; Gao, H.; Laskaris, G.; Weir, W.; Ye, Q.; Ye, Q. J.

2011-10-01

217

Design and optimization of MeV class Compton scattering MEGa-ray sources  

NASA Astrophysics Data System (ADS)

The design and optimization of a Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering source are presented. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. In particular, while it is known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Albert, Felicie; Anderson, S. G.; Betts, S. M.; Cross, R. R.; Ebbers, C. A.; Houck, T. L.; Gibson, D. J.; Marsh, R. A.; Messerly, M.; Shverdin, M. Y.; Wu, S. S.; Hartemann, F. V.; Siders, C. W.; Scarpetti, R. D.; Barty, C. P. J.

2010-11-01

218

X-ray Imaging Based on Compton Scattering  

ScienceCinema

This presentation highlights a number of applications where rapid, low-dose, one-sided Compton imaging is especially desirable and describes typical methods for creating these images. Some of the systems are also capable of scanning an object by simultaneously forming multiple backscatter images of vehicles from different perspectives, such as left, right, and top-down. While each view has limited penetration ability, the combination of views provides a powerful inspection tool that often permits threat objects to be easily discerned, even in a cluttered environment.

219

Intershell correlations in nonresonant Compton scattering of an X-ray photon by an atom  

SciTech Connect

The role of intershell correlations in nonresonant Compton scattering of an X-ray photon by a free multielectron atom is studied theoretically for the Ar atom. The results of calculation are of a predictive nature. The developed mathematical formalism is general in nature and can be applied to a wide set of elements from the Periodic Table, for which the description of the wavefunctions of scattering states in the nonrelativistic Hartree-Fock approximation remains correct.

Hopersky, A. N., E-mail: hopersky_vm_1@rgups.ru; Nadolinsky, A. M.; Ikoeva, K. Kh.; Khoroshavina, O. A. [Rostov State Railway University (Russian Federation)

2011-11-15

220

Development of the balloon-borne sub-MeV gamma-ray Compton camera using an electron-tracking gaseous TPC and a scintillation camera  

NASA Astrophysics Data System (ADS)

We have developed an Electron-Tracking Compton Camera (ETCC) for use onboard a balloon to observe sub-MeV/MeV gamma rays from celestial objects. The ETCC is constructed with a three dimensional gaseous tracker for recoil electrons from Compton scattering, and GSO:Ce pixel scintillator arrays as absorber of the Compton-scattered gamma-ray. By using the ETCC, we can reconstruct the energy and direction of individual gamma rays. We have developed a prototype ETCC with a (30 cm)3 TPC, and tested its performance in the range of 356 - 835 keV in the laboratory. As the result, we succeeded in taking images of gamma ray sources and determined a detection efficiency of 9.0 × 10-6 and an effective area of 8.0 × 10-3 cm2 at 662 keV for the prototype ETCC. Furthermore, we developed a new power saving readout circuit for the scintillators that achieves the electric power consumption of 0.41 W/channel, an energy dynamic range of 81 - 1333 keV, and an energy resolution of 10.3% at full width at half maximum at 662 keV.

Ueno, K.; Mizumoto, T.; Hattori, K.; Higashi, N.; Iwaki, S.; Kabuki, S.; Kishimoto, Y.; Komura, S.; Kubo, H.; Kurosawa, S.; Matsuoka, Y.; Miuchi, K.; Nakamura, K.; Nishimura, H.; Parker, J.; Sato, Y.; Sawano, T.; Takada, A.; Tanimori, T.

2012-01-01

221

Search for Light-Speed Anisotropies Using Compton Scattering of High-Energy Electrons  

NASA Astrophysics Data System (ADS)

Based on the high sensitivity of Compton scattering off ultra relativistic electrons, the possibility of anisotropies in the speed of light is investigated. The result discussed in this contribution is based on the ?-ray beam of the ESRF's GRAAL facility (Grenoble, France) and the search for sidereal variations in the energy of the Compton-edge photons. The absence of oscillations yields the two-sided limit of 1.6 × 10-14 at 95% confidence level on a combination of photon and electron coefficients of the minimal Standard-Model Extension (mSME). This new constraint provides an improvement over previous bounds by one order of magnitude.

Rebreyend, D.; Bocquet, J.-P.; Moricciani, D.; Bellini, V.; Beretta, M.; Casano, L.; Dangelo, A.; di Salvo, R.; Fantini, A.; Franco, D.; Gervino, G.; Ghio, F.; Giardina, G.; Girolami, B.; Giusa, A.; Gurzadyan, V. G.; Kashin, A.; Knyazyan, S.; Lapik, A.; Lehnert, R.; Levi Sandri, P.; Lleres, A.; Mammoliti, F.; Mandaglio, G.; Manganaro, M.; Margarian, A.; Mehrabyan, S.; Messi, R.; Nedorezov, V.; Perrin, C.; Randieri, C.; Rudnev, N.; Russo, G.; Schaerf, C.; Sperduto, M.-L.; Sutera, M.-C.; Turinge, A.; Vegna, V.

2011-12-01

222

Gamma-ray Compton camera imaging with a segmented HPGe  

NASA Astrophysics Data System (ADS)

In this paper, we investigate our concept to develop a ?-ray Compton camera out of a single coaxial High Purity Germanium (HPGe) detector. The imaging properties of the HPGe can be realized by way of a segmented outer contact and digital pulse-shape analysis. Limiting factors in performance will be related to the intrinsic electron momentum in Ge and the noise in the preamplifier JFETs. In addition to discussing these issues, we will present experimental and theoretical imaging studies that we have done using an existing segmented HPGe: the GRETA prototype detector at LBNL.

Schmid, G. J.; Beckedahl, D. A.; Kammeraad, J. E.; Blair, J. J.; Vetter, K.; Kuhn, A.

2001-03-01

223

First refraction contrast imaging via Laser-Compton Scattering X-ray at KEK  

SciTech Connect

Laser-Compton Scattering (LCS) is one of the most feasible techniques for high quality, high brightness, and compact X-ray source. High energy electron beam produced by accelerators scatters off the laser photon at a small spot. As a laser target, we have been developing a pulsedlaser storage cavity for increasing an X-ray flux. The X-ray flux was still inadequate that was 2.1 Multiplication-Sign 10{sup 5}/sec, however, we performed first refraction contrast imaging in order to evaluate the quality of LCS X-ray. Edge enhanced contrast imaging was achieved by changing the distance from sample to detector. The edge enhancement indicates that the LCS X-ray has small source size, i.e. high brightness. We believe that the result has demonstrated good feasibility of linac-based high brightness X-ray sources via laser-electron Compton scatterings.

Sakaue, Kazuyuki; Aoki, Tatsuro; Washio, Masakazu; Araki, Sakae; Fukuda, Masafumi; Terunuma, Nobuhiro; Urakawa, Junji [3-4-1, Okubo, Shinjuku, Tokyo, 169-8555 (Japan); Research Institute for Science and Engineering, Waseda University (Japan); 1-1, Oho, Tsukuba, Ibaraki, 305-0801 Japan, High Energy Accelerator Research Organization (KEK) (Japan)

2012-07-31

224

First refraction contrast imaging via Laser-Compton Scattering X-ray at KEK  

NASA Astrophysics Data System (ADS)

Laser-Compton Scattering (LCS) is one of the most feasible techniques for high quality, high brightness, and compact X-ray source. High energy electron beam produced by accelerators scatters off the laser photon at a small spot. As a laser target, we have been developing a pulsedlaser storage cavity for increasing an X-ray flux. The X-ray flux was still inadequate that was 2.1×105/sec, however, we performed first refraction contrast imaging in order to evaluate the quality of LCS X-ray. Edge enhanced contrast imaging was achieved by changing the distance from sample to detector. The edge enhancement indicates that the LCS X-ray has small source size, i.e. high brightness. We believe that the result has demonstrated good feasibility of linac-based high brightness X-ray sources via laser-electron Compton scatterings.

Sakaue, Kazuyuki; Aoki, Tatsuro; Washio, Masakazu; Araki, Sakae; Fukuda, Masafumi; Terunuma, Nobuhiro; Urakawa, Junji

2012-07-01

225

The results of the in-flight attitude sensor calibration for the Arthur Holly Compton Gamma Ray Observatory  

Microsoft Academic Search

The Arthur Holly Compton Gamma Ray Observatory (GRO) was launched by the shuttle Atlantis in April 1991. This paper presents the results of the attitude sensor calibration that was performed during the early mission. The GSFC Flight Dynamics Facility (FDF) performed an alignment calibration of the two fixed-head star trackers (FHST's) and two fine Sun sensors (FSS's) on board Compton

W. S. Davis; A. H. Eudell; L. S. Kulp; L. A. Lindrose; R. R. Harman

1993-01-01

226

Time-step limits for a Monte Carlo Compton-scattering method  

SciTech Connect

Compton scattering is an important aspect of radiative transfer in high energy density applications. In this process, the frequency and direction of a photon are altered by colliding with a free electron. The change in frequency of a scattered photon results in an energy exchange between the photon and target electron and energy coupling between radiation and matter. Canfield, Howard, and Liang have presented a Monte Carlo method for simulating Compton scattering that models the photon-electron collision kinematics exactly. However, implementing their technique in multiphysics problems that include the effects of radiation-matter energy coupling typically requires evaluating the material temperature at its beginning-of-time-step value. This explicit evaluation can lead to unstable and oscillatory solutions. In this paper, we perform a stability analysis of this Monte Carlo method and present time-step limits that avoid instabilities and nonphysical oscillations by considering a spatially independent, purely scattering radiative-transfer problem. Examining a simplified problem is justified because it isolates the effects of Compton scattering, and existing Monte Carlo techniques can robustly model other physics (such as absorption, emission, sources, and photon streaming). Our analysis begins by simplifying the equations that are solved via Monte Carlo within each time step using the Fokker-Planck approximation. Next, we linearize these approximate equations about an equilibrium solution such that the resulting linearized equations describe perturbations about this equilibrium. We then solve these linearized equations over a time step and determine the corresponding eigenvalues, quantities that can predict the behavior of solutions generated by a Monte Carlo simulation as a function of time-step size and other physical parameters. With these results, we develop our time-step limits. This approach is similar to our recent investigation of time discretizations for the Compton-scattering Fokker-Planck equation.

Densmore, Jeffery D [Los Alamos National Laboratory; Warsa, James S [Los Alamos National Laboratory; Lowrie, Robert B [Los Alamos National Laboratory

2008-01-01

227

Supercontinuum and ultrashort-pulse generation from nonlinear Thomson and Compton scattering  

NASA Astrophysics Data System (ADS)

Nonlinear Thomson and Compton processes, in which energetic electrons collide with an intense optical pulse, are investigated in the framework of classical and quantum electrodynamics. Spectral modulations of the emitted radiation, appearing as either oscillatory or pulsating structures, are observed and explained. It is shown that both processes generate a bandwidth radiation spanning the range of a few MeV, which occurs in a small cone along the propagation direction of the colliding electrons. Most importantly, these broad bandwidth structures are temporarily coherent, which proves that Thomson and Compton processes lead to the generation of a supercontinuum. It is demonstrated that the radiation from the supercontinuum can be synthesized into zeptosecond (possibly even yoctosecond) pulses. This confirms that Thomson and Compton scattering can be used as sources of an ultrashort radiation, which opens routes to new physical domains for strong laser physics. We study properties of generated pulses arising in the classical and in the exclusively quantum regime of electron-laser-field interaction, and we attribute them to the behavior of global phases of Thomson and Compton scattering probability amplitudes.

Krajewska, K.; Twardy, M.; Kami?ski, J. Z.

2014-03-01

228

Comment on ``Anomalous neutron Compton scattering from molecular hydrogen''  

NASA Astrophysics Data System (ADS)

Claims in the paper by Chatizidimitiou-Dreismann [Phys. Rev. B 72, 054123 (2005)] that our analysis of the keV neutron scattering data is incorrect are shown to be wrong. Their analysis neglects the effect of the neutron attenuation in the relatively thick samples, thus creating an artificial anomaly of ˜21% in the scattering intensity ratio of H2O relative to that of D2O .

Moreh, R.; Block, R. C.; Danon, Y.

2007-02-01

229

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

1992-01-01

230

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1,2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.

231

Observation of gamma ray bursts and flares by the EGRET telescope on the Compton Gamma Ray observatory  

NASA Astrophysics Data System (ADS)

The Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray observatory has observed energetic gamma ray bursts and flares. On May 3, 1991, EGRET detected a gamma ray burst both in the energy measuring NaI (Tl) scintillator and independently in the spark chamber imaging assembly. The NaI spectra were accumulated by a special BURST mode of EGRET. The spectra were measured over a range from 1 to 200 MeV, in three sequential spectra of 1, 2, and 4 seconds. During the peak of the burst, six individual gamma rays were detected in the spark chamber, allowing a determination of the burst arrival direction. The intense flares of June were also detected. A solar flare on June 4 was observed to last for several minutes and for a brief time, less than a minute, had significant emission of gamma rays exceeding 150 MeV.

Schneid, E. J.; Bertsch, D. L.; Fichtel, C. E.; Hartman, R.; Hunter, S. D.; Kwok, P. W.; Mattox, J. R.; Sreekumar, P.; Thompson, D. J.; Kanbach, G.; Mayer-Hasselwander, M. A.; von Montigny, C.; Pinkau, K.; Rothermel, H.; Sommer, M.; Kniffen, D. A.; Lin, Y. C.; Michelson, P. F.; Nolan, P. L.

1991-09-01

232

Dispersion theory of proton Compton scattering in the first and second resonance regions  

SciTech Connect

Dispersion theory of proton Compton scattering is extended to energies up to {approximately}1 GeV where excitations of higher resonances and nonresonance double-pion photoproduction become important photoabsorption mechanisms. To saturate s-channel dispersion relations, the VPI partial-wave analysis of single-pion photoproduction and resonance photocouplings is used. Models for double-pion photoproduction and dispersion asymptotic contributions are constructed. The latter are mainly given by {pi}{sup 0} and {sigma}(600) exchanges. Being used in dispersion calculations, they result in a reasonable agreement with all available data on both differential cross sections and polarization observables in Compton scattering. Some unsolved problems are outlined. {copyright} {ital 1997} {ital The American Physical Society}

Lvov, A.I.; Petrunkin, V.A. [P. N. Lebedev Physical Institute, Leninsky Prospect 53, Moscow 117924 (Russia)] [P. N. Lebedev Physical Institute, Leninsky Prospect 53, Moscow 117924 (Russia); Schumacher, M. [II. Physikalisches Institut, Universitaet Goettingen, Bunsenstrasse 7-9, D-37073, Goettingen (Germany)] [II. Physikalisches Institut, Universitaet Goettingen, Bunsenstrasse 7-9, D-37073, Goettingen (Germany)

1997-01-01

233

Monte Carlo Modeling of Compton-Scattering Angles in a Mildly Relativistic Plasma  

NASA Astrophysics Data System (ADS)

If the inversion method is applied to random-number generation in a Monte Carlo simulation of Compton-scattering, we often encounter cubic equations. These may be solved using well-known numerical iterative methods, such as the Newton-Raphson, or bisection methods. These numerical methods, however, may lead to many iterations, which should be avoided for modeling efficiency. We present explicit inversion formulae of two cubic equations arising from the modeling of Compton-scattering angles in a mildly or weakly relativistic plasma. Explicit analytical methods are superior to any other rejection or numerical inversion methods in terms of the modeling efficiency, and will be useful for Monte Carlo simulations of X-ray reflection from cold material and the Sunyaev-Zel'dovich effect.

Seon, Kwang-Il

2006-04-01

234

Imaging doped holes in a cuprate superconductor with high-resolution Compton scattering.  

PubMed

The high-temperature superconducting cuprate La(2-x)Sr(x)CuO(4) (LSCO) shows several phases ranging from antiferromagnetic insulator to metal with increasing hole doping. To understand how the nature of the hole state evolves with doping, we have carried out high-resolution Compton scattering measurements at room temperature together with first-principles electronic structure computations on a series of LSCO single crystals in which the hole doping level varies from the underdoped (UD) to the overdoped (OD) regime. Holes in the UD system are found to primarily populate the O 2p(x)/p(y) orbitals. In contrast, the character of holes in the OD system is very different in that these holes mostly enter Cu d orbitals. High-resolution Compton scattering provides a bulk-sensitive method for imaging the orbital character of dopants in complex materials. PMID:21527674

Sakurai, Y; Itou, M; Barbiellini, B; Mijnarends, P E; Markiewicz, R S; Kaprzyk, S; Gillet, J-M; Wakimoto, S; Fujita, M; Basak, S; Wang, Yung Jui; Al-Sawai, W; Lin, H; Bansil, A; Yamada, K

2011-05-01

235

Commissioning of a high-brightness photoinjector for Compton scattering x-ray sources  

NASA Astrophysics Data System (ADS)

Compton scattering of intense laser pulses with ultra-relativistic electron beams has proven to be an attractive source of high-brightness x-rays with keV to MeV energies. This type of x-ray source requires the electron beam brightness to be comparable with that used in x-ray free-electron lasers and laser and plasma based advanced accelerators. We describe the development and commissioning of a 1.6 cell RF photoinjector for use in Compton scattering experiments at LLNL. Injector development issues such as RF cavity design, beam dynamics simulations, emittance diagnostic development, results of sputtered magnesium photo-cathode experiments, and UV laser pulse shaping are discussed. Initial operation of the photoinjector is described and transverse phase space measurements are presented.

Anderson, Scott; Gibson, David; Messerly, Mike; Shverdin, Miroslav; Tremaine, Aaron; Hartemann, Fred; Siders, Craig; Barty, Christopher; Badakov, Hristo; Frigola, Pedro; O'Shea, Brendan; Rosenzweig, James

2007-11-01

236

Observation of pulsed x-ray trains produced by laser-electron Compton scatterings  

SciTech Connect

X-ray generation based on laser-electron Compton scattering is one attractive method to achieve a compact laboratory-sized high-brightness x-ray source. We have designed, built, and tested such a source; it combines a 50 MeV multibunch electron linac with a mode-locked 1064 nm laser stored and amplified in a Fabry-Perot optical cavity. We directly observed trains of pulsed x rays using a microchannel plate detector; the resultant yield was found to be 1.2x10{sup 5} Hz in good agreement with prediction. We believe that the result has demonstrated good feasibility of linac-based compact x-ray sources via laser-electron Compton scatterings.

Sakaue, Kazuyuki; Washio, Masakazu [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Araki, Sakae; Fukuda, Masafumi; Higashi, Yasuo; Honda, Yosuke; Omori, Tsunehiko; Taniguchi, Takashi; Terunuma, Nobuhiro; Urakawa, Junji [KEK (High Energy Accelerator Research Organization), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Sasao, Noboru [Department of Physics, Kyoto University, Sakyo, Kyoto 606-8502 (Japan)

2009-12-15

237

Compton Effect  

NSDL National Science Digital Library

The Compton Effect model simulates the the scattering of light off of an electron, the Compton effect. Compton used the idea that light behaves like a particle to explain light-electron (photon-electron) scattering. He used the relation for the energy and momentum of the photon and the relativistic expression for the energy of the electron, and applied relativistic energy and momentum conservation for the collision. The wavelength shift of the light depend on the angle of the scattered photon (and the electron). By changing the scattering angle in the simulation, the angle of the scattered photon changes according to Compton's equation. The panel on the left shows the experimental set up, while the panel on the right shows the resulting photon wavelength from the scattering. In a typical Compton experiment, light is scattered off of the electrons in an atom, and there is little scattering due to the more tightly held electrons while there is more scattering due to the less tightly held electrons. This is what is responsible for the two peak distribution shown. The Compton Effect model was created using the Easy Java Simulations (EJS) modeling tool. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the ejs_qm_compton.jar file will run the program if Java is installed.

Palop, Jose I.

2010-12-12

238

An improvement of Compton scatter imaging with wide aperture detectors a Monte Carlo study  

Microsoft Academic Search

A novel NDT (nondestructive testing) imaging technique which is based on the measurement of Compton-scattered photons and uses wide-aperture detectors has been developed. With this technique, the inspection speed can be improved because the scanning activities can be reduced by one degree of freedom. Using wide-aperture detectors serves to simplify the design of measurement systems, and the data collection time

Houlung Lee; Edward S. Kenney

1991-01-01

239

MultiBeam Compton Scattering Monochromatic Tunable Hard X-Ray Source  

Microsoft Academic Search

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo (UTNS). Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35

Mitsuru Uesaka; Fumito Sakamoto; Atsushi Fukasawa; Haruyuki Ogino; Tomohiko Yamamoto; De Meng; Katsuhiro Dobashi; Toshinobu Miyoshi; Toshiyasu Higo; Mitsuo Akemoto; Junji Urakawa

2007-01-01

240

Medical Application of MultiBeam Compton Scattering Monochromatic Tunable Hard X-Ray Source  

Microsoft Academic Search

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo. Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35 MeV

Mitsuru Uesaka; Katsuhiro Dobashri; Fumito Sakamoto; Atsushi Fukasawa; Haruyuki Ogino; Tomohiko Yamamoto; De Meng; Toshinobu Miyoshi; Junji Urakawa; Toshiyasu Higo; Mitsuo Akemoto

2007-01-01

241

X-Band Linac Beam-Line for Medical Compton Scattering X-Ray Source  

Microsoft Academic Search

Compton scattering hard X-ray source for 10-40 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineer ing Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and

Katsuhiro Dobashi; M. Uesaka; A. Fukasawa; F. Ebina; T. Kaneyasu; H. Ogino; F. Sakamoto; T. Yamomoto; J. Urakawa; T. Higo; M. Akemoto; H. Hayano

2005-01-01

242

X-band RF gun and linac for medical Compton scattering X-ray source  

Microsoft Academic Search

Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo

Katsuhito Dobashi; Mitsuru Uesaka; Atsushi Fukasawa; Fumito Sakamoto; Futaro Ebina; Haruyuki Ogino; Junji Urakawa; Toshiyasu Higo; Mitsuo Akemoto; Hitoshi Hayano; Keiichi Nakagawa

2004-01-01

243

Upgrade of X-band thermionic cathode RF gun for Compton scattering X-ray source  

Microsoft Academic Search

A Compton scattering X-ray source consisting of an X-band (11.424GHz) electron linear accelerator (linac) and Q-switched Nd: YAG laser is currently under development at the University of Tokyo. Monochromatic X-rays are required for a variety of medical and biological applications. The X-ray source produces monochromatic X-rays via collision between a 35-MeV multi-bunch (104 bunches in a 1?s RF pulse) electron

Yoshihiro Taniguchi; Fumito Sakamoto; Takuya Natsui; Tomohiko Yamamoto; Eiko Hashimoto; Kiwoo Lee; Mitsuru Uesaka; Mitsuhiro Yoshida; Toshiyasu Higo; Shigeki Fukuda; Mitsuo Akemoto

2009-01-01

244

X-ray phase-contrast imaging with an Inverse Compton Scattering source  

Microsoft Academic Search

Single-shot in-line phase-contrast imaging with the Inverse Compton Scattering X-ray source available at ATF (Accelerator Test Facility) at Brookhaven National Laboratory is experimentally demonstrated. Phase-contrast images of polymer wires are obtained with a single X-ray pulse whose time length is about 1 picosecond. The edge-enhancement effect is clearly visible in the images and simulations show a quantitative agreement with experimental

M. Endrizzi; M. Carpinelli; P. Delogu; P. Oliva; B. Golosio; T. E. Gureyev; U. Bottigli; A. Stefanini

2010-01-01

245

On the Spectral Shape of Radiation due to Inverse Compton Scattering Close to the Maximum Cutoff  

NASA Astrophysics Data System (ADS)

The spectral shape of radiation due to inverse Compton scattering is analyzed in the Thomson and the Klein-Nishina regime for electron distributions with exponential cutoff. We derive analytical, asymptotic expressions for the spectrum close to the maximum cutoff region. We consider monoenergetic, Planckian, and synchrotron photons as target photon fields. These approximations provide a direct link between the distribution of parent electrons and the upscattered spectrum at the cutoff region.

Lefa, E.; Kelner, S. R.; Aharonian, F. A.

2012-07-01

246

Measurement of deeply virtual Compton scattering and its t-dependence at HERA  

Microsoft Academic Search

A measurement of elastic deeply virtual Compton scattering ??p??p using e?p collision data recorded with the H1 detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 145 pb?1. The cross section is measured as a function of the virtuality Q2 of the exchanged photon and the centre-of-mass energy W of the ??p system in

F. D. Aaron; A. Aktas; C. Alexa; V. Andreev; B. Antunovic; S. Aplin; A. Asmone; A. Astvatsatourov; S. Backovic; A. Baghdasaryan; P. Baranov; E. Barrelet; W. Bartel; S. Baudrand; M. Beckingham; K. Begzsuren; O. Behnke; O. Behrendt; A. Belousov; N. Berger; J. C. Bizot; M.-O. Boenig; V. Boudry; I. Bozovic-Jelisavcic; J. Bracinik; G. Brandt; M. Brinkmann; V. Brisson; D. Bruncko; F. W. Büsser; A. Bunyatyan; G. Buschhorn; L. Bystritskaya; A. J. Campbell; K. B. Cantun Avila; F. Cassol-Brunner; K. Cerny; V. Cerny; V. Chekelian; A. Cholewa; J. G. Contreras; J. A. Coughlan; G. Cozzika; J. Cvach; J. B. Dainton; K. Daum; M. Deak; Y. de Boer; B. Delcourt; M. Del Degan; J. Delvax; A. De Roeck; E. A. De Wolf; C. Diaconu; V. Dodonov; A. Dossanov; G. Eckerlin; V. Efremenko; S. Egli; R. Eichler; F. Eisele; A. Eliseev; E. Elsen; S. Essenov; A. Falkiewicz; P. J. W. Faulkner; L. Favart; A. Fedotov; R. Felst; J. Feltesse; L. Finke; M. Fleischer; A. Fomenko; G. Franke; T. Frisson; E. Gabathuler; J. Gayler; S. Ghazaryan; A. Glazov; I. Glushkov; L. Goerlich; M. Goettlich; N. Gogitidze; S. Gorbounov; M. Gouzevitch; C. Grab; T. Greenshaw; B. R. Grell; G. Grindhammer; S. Habib; D. Haidt; M. Hansson; G. Heinzelmann; C. Helebrant; R. C. W. Henderson; H. Henschel; G. Herrera; M. Hildebrandt; K. H. Hiller; D. Hoffmann; R. Horisberger; A. Hovhannisyan; T. Hreus; M. Jacquet; M. E. Janssen; X. Janssen; V. Jemanov; L. Jönsson; D. P. Johnson; A. W. Jung; H. Jung; M. Kapichine; J. Katzy; I. R. Kenyon; C. Kiesling; M. Klein; C. Kleinwort; T. Klimkovich; A. Knutsson; R. Kogler; V. Korbel; P. Kostka; M. Kraemer; K. Krastev; J. Kretzschmar; A. Kropivnitskaya; K. Krüger; M. P. J. Landon; W. Lange; G. Laštovi?ka-Medin; P. Laycock; A. Lebedev; G. Leibenguth; V. Lendermann; S. Levonian; G. Li; L. Lindfeld; K. Lipka; A. Liptaj; B. List; J. List; N. Loktionova; R. Lopez-Fernandez; V. Lubimov; A.-I. Lucaci-Timoce; L. Lytkin; A. Makankine; E. Malinovski; P. Marage; Ll. Marti; H.-U. Martyn; S. J. Maxfield; A. Mehta; K. Meier; A. B. Meyer; H. Meyer; J. Meyer; V. Michels; S. Mikocki; I. Milcewicz-Mika; A. Mohamed; F. Moreau; A. Morozov; J. V. Morris; M. U. Mozer; M. Mudrinic; K. Müller; P. Murín; K. Nankov; B. Naroska; Th. Naumann; P. R. Newman; C. Niebuhr; A. Nikiforov; G. Nowak; K. Nowak; M. Nozicka; B. Olivier; J. E. Olsson; S. Osman; D. Ozerov; V. Palichik; I. Panagoulias; M. Pandurovic; Th. Papadopoulou; C. Pascaud; G. D. Patel; H. Peng; E. Perez; D. Perez-Astudillo; A. Perieanu; A. Petrukhin; I. Picuric; S. Piec; D. Pitzl; R. Pla?akyt?; B. Povh; T. Preda; P. Prideaux; V. Radescu; A. J. Rahmat; N. Raicevic; A. Raspiareza; T. Ravdandorj; P. Reimer; C. Risler; E. Rizvi; P. Robmann; B. Roland; R. Roosen; A. Rostovtsev; Z. Rurikova; S. Rusakov; D. Salek; F. Salvaire; D. P. C. Sankey; M. Sauter; E. Sauvan; S. Schmidt; C. Schmitz; L. Schoeffel; A. Schöning; H.-C. Schultz-Coulon; F. Sefkow; R. N. Shaw-West; I. Sheviakov; L. N. Shtarkov; T. Sloan; I. Smiljanic; P. Smirnov; Y. Soloviev; D. South; V. Spaskov; A. Specka; Z. Staykova; M. Steder; B. Stella; J. Stiewe; U. Straumann; D. Sunar; T. Sykora; V. Tchoulakov; G. Thompson; P. D. Thompson; T. Toll; F. Tomasz; T. H. Tran; D. Traynor; T. N. Trinh; P. Truöl; I. Tsakov; B. Tseepeldorj; I. Tsurin; J. Turnau; E. Tzamariudaki; K. Urban; A. Valkárová; C. Vallée; P. Van Mechelen; A. Vargas Trevino; Y. Vazdik; S. Vinokurova; V. Volchinski; G. Weber; R. Weber; D. Wegener; C. Werner; M. Wessels; Ch. Wissing; R. Wolf; E. Wünsch; V. Yeganov; J. Žá?ek; J. Zálešák; Z. Zhang; A. Zhelezov; Y. C. Zhu; T. Zimmermann; H. Zohrabyan; F. Zomer

2008-01-01

247

Treatment of Compton scattering of linearly polarized photons in Monte Carlo codes  

NASA Astrophysics Data System (ADS)

The basic formalism of Compton scattering of linearly polarized photons is reviewed, and some simple prescriptions to deal with the transport of polarized photons in Monte Carlo simulation codes are given. Fortran routines, based on the described method, have been included in MCNP, a widely used code for neutrons, photons and electrons transport. As this improved version of the code can be of general use, the implementation and the procedures to employ the new version of the code are discussed.

Matt, Giorgio; Feroci, Marco; Rapisarda, Massimo; Costa, Enrico

1996-10-01

248

X-ray imaging with laser-Compton scattering X-ray at AIST  

Microsoft Academic Search

An X-ray facility with a compact electron linear accelerator via laser-Compton scattering (LCS X-ray) is recently installed at AIST. The LCS X-ray facility in approximately 8-m square consists of a 40-MeV linac, a femtosecond terawatt laser and an X-ray beamline. The LCS X-ray facility produces quasi-monochromatic X-rays with energy in the range of 12 ~ 40 keV which are commonly

M. Yasumoto; R. Kuroda; H. Ikeura-Sekiguchi; H. Toyokawa; N. Sei; H. Ogawa; M. Koike; K. Yamada; K. Mori; F. Sakai; S. Tamura

2009-01-01

249

Laser Compton scattering experiments and the latest developments in construction of experimental facilities at SINAP  

Microsoft Academic Search

In this article, we report the two terms Laser Compton Scattering (LCS) via interaction experiments at 100 MeV linear accelerator of SINAP. The monochromatic X-rays were generated by a 108.1 MeV, 2.5 ns electron beam colliding with two Nd:YAG lasers of 113mJ\\/pulse,35 ns and 2J\\/pulse, 10 ns, respectively, and demonstrate the latest developments in construction of experimental facilities at SINAP:

W. Luo; W. Xu; Q. Y. Pan; G. T. Fan; G. W. Fan; Y. J. Li; G. Q. Lin; B. J. Xu; Y. Xu; Z. Yan; L. F. Yang

2009-01-01

250

First measurement of Z\\/? ? production in Compton scattering of quasi-real photons  

Microsoft Academic Search

We report the first observation of Z\\/?? production in Compton scattering of quasi-real photons. This is a subprocess of the reaction e+e??e+e?Z\\/??, where one of the final state electrons is undetected. Approximately 55pb?1 of data collected in the year 1997 at an e+e? centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been analysed. The Z\\/?? from

G. Abbiendi; K. Ackerstaff; Gideon Alexander; J. Allison; N. Altekamp; K. J. Anderson; S. Anderson; S. Arcelli; S. F. Ashby; D A Axen; Georges Azuelos; A. H. Ball; E. Barberio; R. J. Barlow; R. Bartoldus; J Richard Batley; S. Baumann; J. Bechtluft; T. Behnke; K. W. Bell; G. Bella; A. Bellerive; Stanislaus Cornelius Maria Bentvelsen; S. Bethke; O. Biebel; A. Biguzzi; S. D. Bird; Volker Blobel; Ian J Bloodworth; M. Bobinski; P. Bock; J. Böhme; D. Bonacorsi; M. Boutemeur; S. Braibant; P G Bright-Thomas; L. Brigliadori; R. M. Brown; Helfried J Burckhart; C. Burgard; R. Bürgin; P. Capiluppi; R. K. Carnegie; A. A. Carter; J. R. Carter; C. Y. Chang; D. G. Charlton; D. Chrisman; C. Ciocca; P. E. L. Clarke; E. Clay; I. Cohen; J. E. Conboy; O. C. Cooke; C. Couyoumtzelis; R. L. Coxe; M. Cuffiani; S. Dado; G. M. Dallavalle; R. Davis; S. De Jong; L. A. del Pozo; A. de Roeck; Klaus Desch; B. Dienes; M. S. Dixit; J. Dubbert; E. Duchovni; G. Duckeck; I. P. Duerdoth; D. Eatough; P. G. Estabrooks; E. Etzion; H. G. Evans; Franco Luigi Fabbri; M. Fanti; A. A. Faust; F. Fiedler; M. Fierro; I. Fleck; R. Folman; A. Fürtjes; D. I. Futyan; P. Gagnon; J. W. Gary; J. Gascon; S. M. Gascon-Shotkin; G. Gaycken; C. Geich-Gimbel; G. Giacomelli; P. Giacomelli; V. Gibson; W. R. Gibson; D. M. Gingrich; D A Glenzinski; J. Goldberg; W. Gorn; C. Grandi; E. Gross; Jacob Grunhaus; M. Gruwé; G. G. Hanson; M. Hansroul; K. Harder; C. K. Hargrove; C. Hartmann; M. Hauschild; C. M. Hawkes; R. Hawkings; Richard J Hemingway; M. Herndon; G. Herten; R. D. Heuer; M. D. Hildreth; J. C. Hill; S. J. Hillier; P. R. Hobson; A. Hocker; R James Homer; A. K. Honma; D. Horváth; K. R. Hossain; P. Hüntemeyer; P. Igo-Kemenes; D. C. Imrie; K. Ishii; F. R. Jacob; A. Jawahery; H. Jeremie; Martin Paul Jimack; C. R. Jones; P. Jovanovic; T. R. Junk; D A Karlen; V G Kartvelishvili; K. Kawagoe; T. Kawamoto; P. I. Kayal; Richard K Keeler; R. G. Kellogg; B. W. Kennedy; A. Klier; S. Kluth; T. Kobayashi; M. Kobel; D. S. Koetke; T. P. Kokott; M. Kolrep; S. Komamiya; R. V. Kowalewski; T. Kress; P. Krieger; J. von Krogh; T. Kuhl; P. Kyberd; G. D. Lafferty; G. D. Lafferty; J. Lauber; S. R. Lautenschlager; I. Lawson; J. G. Layter; D. Lazic; A. M. Lee; Daniel Lellouch; J. Letts; L. Levinson; R. Liebisch; B. List; C. Littlewood; A. W. Lloyd; S. L. Lloyd; F. K. Loebinger; G. D. Long; Michael J Losty; D. Liu; A. Macchiolo; A L MacPherson; W F Mader; M. Mannelli; S. Marcellini; C. Markopoulos; A. J. Martin; G. Martinez; T. Mashimo; P. Mättig; W. J. McDonald; E. A. Mckigney; T. J. McMahon; R. A. McPherson; F. Meijers; S. Menke; F. S. Merritt; H. Mes; J. Meyer; Aldo Michelini; S. Mihara; G. Mikenberg; D. J. Miller; R. Mir; W. Mohr; A. Montanari; T. Mori; K. Nagai; I. Nakamura; H. A. Neal; B. Nellen; R. Nisius; S. W. O'Neale; F. G. Oakham; F. Odorici; H. O. Ogren; M. J. Oreglia; S. Orito; J. Pálinkás; G. Pásztor; J. R. Pater; G. N. Patrick; J. Patt; R. Perez-Ochoa; S. Petzold; P. Pfeifenschneider; J. E. Pilcher; James L Pinfold; D. E. Plane; P R Poffenberger; J. Polok; M B Przybycien; C. Rembser; Hartmut Rick; S. Robertson; S. Robertson; N L Rodning; J. M. Roney; K. Roscoe; A. M. Rossi; Y. Rozen; K. Runge; O. Runolfsson; D. R. Rust; K. Sachs; T. Saeki; O. Sahr; W. M. Sang; E Sarkisyan-Grinbaum; C. Sbarra; A. D. Schaile; O. Schaile; F. Scharf; P. Scharff-Hansen; J. Schieck; B. Schmitt; S. Schmitt; A. Schöning; M. Schröder; M. Schumacher; C. Schwick; W. G. Scott; T. Seiler; R. Seuster; T. G. Shears; B. C. Shen; C. H. Shepherd-Themistocleous; P. Sherwood; G. P. Siroli; A. Sittler; A. Sittler; A. M. Smith; G. A. Snow; Randall J Sobie; S. Söldner-Rembold; M. Sproston; A. Stahl; K. Stephens; J. Steuerer; K. Stoll; D. Strom; R. Ströhmer; B. Surrow; S. D. Talbot; S. Tanaka; P. Taras; S. Tarem; R. Teuscher; M. Thiergen; E. von Törne; E. Torrence; S. Towers; I. Trigger; Z L Trócsányi; E. Tsur; A. S. Turcot; M. F. Turner-Watson; R. Van Kooten; P. Vannerem; M. Verzocchi; H. Voss; F. Wäckerle; A. Wagner; C. P. Ward; D. R. Ward; P. M. Watkins; A. T. Watson; N. K. Watson; P. S. Wells; N. Wermes; J. S. White; G. W. Wilson; J. A. Wilson; T. R. Wyatt; S. Yamashita; G. Yekutieli; V. Zacek; D. Zer-Zion

1998-01-01

251

Time-step limits for a Monte Carlo Compton-scattering method  

SciTech Connect

We perform a stability analysis of a Monte Carlo method for simulating the Compton scattering of photons by free electron in high energy density applications and develop time-step limits that avoid unstable and oscillatory solutions. Implementing this Monte Carlo technique in multi physics problems typically requires evaluating the material temperature at its beginning-of-time-step value, which can lead to this undesirable behavior. With a set of numerical examples, we demonstrate the efficacy of our time-step limits.

Densmore, Jeffery D [Los Alamos National Laboratory; Warsa, James S [Los Alamos National Laboratory; Lowrie, Robert B [Los Alamos National Laboratory

2009-01-01

252

Generalized parton distributions in the valence region from deeply virtual Compton scattering.  

PubMed

This work reviews the recent developments in the field of generalized parton distributions (GPDs) and deeply virtual Compton scattering in the valence region, which aim at extracting the quark structure of the nucleon. We discuss the constraints which the present generation of measurements provide on GPDs, and examine several state-of-the-art parametrizations of GPDs. Future directions in this active field are discussed. PMID:23722105

Guidal, Michel; Moutarde, Hervé; Vanderhaeghen, Marc

2013-06-01

253

Nonlinear Compton scattering of ultrashort intense laser pulses  

SciTech Connect

The scattering of temporally shaped intense laser pulses off electrons is discussed by means of manifestly covariant quantum electrodynamics. We employ a framework based on Volkov states with a time-dependent laser envelope in light-cone coordinates within the Furry picture. An expression for the cross section is constructed unambiguously in respect of the pulse length. A broad distribution of scattered photons with a rich pattern of subpeaks like that obtained in Thomson scattering is found. These broad peaks may overlap at sufficiently high laser intensity, rendering inappropriate the notion of individual harmonics. The limit of monochromatic plane waves as well as the classical limit of Thomson scattering are discussed. As a main result, a scaling law is presented connecting the Thomson limit with the general result for arbitrary kinematics. In the overlapping regions of the spectral density, the classical and quantum calculations give different results, even in the Thomson limit. Thus, a phase-space region is identified where the differential photon distribution is strongly modified by quantum effects.

Seipt, D.; Kaempfer, B. [Helmholtz-Zentrum Dresden-Rossendorf, P.O. Box 510119, D-01314 Dresden (Germany)

2011-02-15

254

X-ray polarization by Compton scattering in Seyfert galaxies.  

NASA Astrophysics Data System (ADS)

The authors have calculated, by means of Montecarlo simulations, the dependence of the intensity and of the degree of polarization on the inclination angle and on the energy of the radiation reflected by cold, optically thick accreting matter located close to the central X-ray source; they have also calculated the polarization of the radiation scattered by a cloud of free electrons possibly surrounding the X-ray source and the Broad Lines Region.

Matt, G.; Perola, G. C.; Piro, L.

255

In-Flight Calibration of EGRET on the Compton Gamma-Ray Observatory  

NASA Astrophysics Data System (ADS)

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory has been operating for over 7 yr since its launch in 1991 April. This span of time far exceeds the design lifetime of 2 yr. As the instrument has aged, several changes have occurred owing to spark chamber gas exchanges as well as some hardware degradation and failures, all of which have an influence on the instrument sensitivity. This paper describes postlaunch measurements and analysis that are done to calibrate the instrument response functions. The updated instrument characteristics are incorporated into the analysis software.

Esposito, J. A.; Bertsch, D. L.; Chen, A. W.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Lin, Y. C.; Mayer-Hasselwander, H. A.; McDonald, L. M.; Michelson, P. F.; von Montigny, C.; Mukherjee, R.; Nolan, P. L.; Reimer, O. L.; Schneid, E.; Sreekumar, P.; Thompson, D. J.; Tompkins, W. F.; Willis, T. D.

1999-07-01

256

On Deeply Virtual Compton Scattering at Next-to-Leading Order  

NASA Astrophysics Data System (ADS)

Deeply virtual Compton scattering in the near forward kinematic region is the golden access to Generalized Parton Distributions. We studied the {{O}(?_S)} corrections to the scattering amplitude for both spacelike and timelike kinematics relevant respectively to the leptoproduction of a real photon and to the photoproduction of a lepton pair. It turns out that these corrections are phenomenologically important and that the gluonic contributions are by no means negligible, even in the moderate energy range of JLab12 and of the COMPASS-II experiment at CERN.

Moutarde, H.; Pire, B.; Sabatié, F.; Szymanowski, L.; Wagner, J.

2014-03-01

257

Breakdown of the Born-Oppenheimer description explains neutron Compton-scattering anomaly  

SciTech Connect

Several neutron Compton scattering experiments reveal an apparent drop of the proton cross section when the collision time {tau}{sub q} is around 1 fs. Such small {tau}{sub q} corresponds to a large energy spread of the proton wave packet after collision, allowing it to access excited electronic levels. This nonadiabatic excitation of electrons leads to a distortion of the shape of the neutron scattering response function with some redistribution of intensity at energies higher than the nuclear recoil energy and a slight shift of the main neutron intensity peak to lower energies.

Gidopoulos, Nikitas I. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon, OX11 0QX (United Kingdom)

2005-02-01

258

Compton e+ Source Overview (ring + Erl + Linac)  

NASA Astrophysics Data System (ADS)

Short reviews of Compton e+ sources R&D for ILC are given. Especially, the Compton sources using Ring and ERL are discussed according to the scheme of truly 300Hz conventional e+ source with the change of the positron generation scheme from nonpolarized to highly polarized e+. As we have proposed the Ring Compton source since 2005, the improvement of the design is described. The technologies for X-ray and Gamma-ray source based on the inverse-Compton scattering have been improved by recent fiber laser and high finesse optical cavity developments.

Urakawa, Junji

2013-10-01

259

Comptonization Signatures in the Prompt Emission of Gamma-Ray Bursts  

NASA Astrophysics Data System (ADS)

We report results of a systematic study of the broadband (2-2000 keV) time-resolved prompt emission spectra of a sample of gamma-ray bursts (GRBs) detected with both Wide Field Cameras (WFCs) on board the BeppoSAX satellite and the Burst and Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory. The main goal of this paper is to test spectral models of the GRB prompt emission that have recently been proposed. In particular, we test a recent photospheric model proposed, i.e., blackbody plus power law, the addition of a blackbody emission to the Band function in the cases in which this function does not fit the data, and a recent Comptonization model. By considering the few spectra for which the simple Band function does not provide a fully acceptable fit to the data, we find a statistically significant better fit by adding a blackbody to this function only in one case. We confirm earlier results found fitting the BATSE spectra alone with a blackbody plus power law. Instead, when the BATSE GRB spectra are joined to those obtained with WFCs (2-28 keV), this model becomes unacceptable in most time intervals in which we subdivide the GRB light curves. We find instead that the Comptonization model is always acceptable, even in the few cases in which the Band function is inconsistent with the data. We discuss the implications of these results.

Frontera, F.; Amati, L.; Farinelli, R.; Dichiara, S.; Guidorzi, C.; Landi, R.; Titarchuk, L.

2013-12-01

260

Anomalous neutron Compton scattering: Comparison of the convolution approximation with a model-free approach  

NASA Astrophysics Data System (ADS)

A shortfall of the scattering intensity from protons has been observed in liquids (water, benzene, etc.) and solids (metal hydrogen systems, organic polymers, etc.) using neutron Compton scattering (NCS). However, the suitability of the conventional NCS data reduction scheme, used to obtain the scattering intensities, based on the convolution approximation (CA) of the nuclear momentum distribution with the instrument resolution function has been questioned. In the present work the commonly used data reduction scheme is compared to a model-free approach [B. Dorner, J. Neutron Res. (to be published)] that is independent of the form of the momentum distribution and the resolution function. Specifically, the ratios of the scattering cross section density of H to C are presented for polyethylene. The model-free approach is shown to lead to the same results as for experimental data published earlier and treated with the CA thus addressing a great part of the previous comments.

Krzystyniak, M.; Chatzidimitriou-Dreismann, C. A.

2005-11-01

261

Photon generation by laser-Compton scattering at the KEK-ATF  

NASA Astrophysics Data System (ADS)

We performed a photon generation experiment by laser-Compton scattering at the KEK-ATF, aiming to develop a Compton based polarized positron source for linear colliders. In the experiment, laser pulses with a 357 MHz repetition rate were accumulated and their power was enhanced by up to 250 times in the Fabry-Perot optical resonant cavity. We succeeded in synchronizing the laser pulses and colliding them with the 1.3 GeV electron beam in the ATF ring while maintaining the laser pulse accumulation in the cavity. As a result, we observed 26.0±0.1 photons per electron-laser pulse crossing, which corresponds to a yield of 10 8 photons in a second.

Miyoshi, S.; Akagi, T.; Araki, S.; Funahashi, Y.; Hirose, T.; Honda, Y.; Kuriki, M.; Li, X.; Okugi, T.; Omori, T.; Pei, G.; Sakaue, K.; Shimizu, H.; Takahashi, T.; Terunuma, N.; Urakawa, J.; Ushio, Y.; Washio, M.

2010-11-01

262

A Compton filter to improve photopeak intensity evaluation in gamma ray spectra  

NASA Astrophysics Data System (ADS)

A procedure for filtering the photopeak intensity from the Compton continuum interference is described. A continuum energy region of up to 0.478 and the 0.662 MeV photopeak are well defined in a cesium-137 theoretical spectrum. The filter was applied to a high intensity Compton region in the gamma spectrum obtained by the attenuation measurements in laboratory experiments. A Cs-137 ( ? = 0.662 MeV) source, of 4 m Ci, steel tubes and a NaI detector was utilized for measuring the catalyst density in a collimated gamma beam. Such an assembly simulates the measuring conditions for gamma tomography in the riser of a FCC-fluid catalyst cracking unit. A Canberra multichannel data acquisition, records the gamma spectrum whose data file is exported to the Matlab software. Following the spectrum reconstruction, the peak area evaluation in both systems, shows a good agreement. Based on the Fourier transform equation, a filtering method for the photopeak, using Matlab functions, was developed. By means of a lowpass filter that lets the low frequencies pass, but not the high frequencies. The filtering results in a significant reduction in the interference from the Compton effect on the photopeak. For little interference and also for a high continuum background under a nonsymmetrical photopeak the filtering works. After the filtering process the peak becomes fairly similar to a Gaussian curve and the liquid counts are enhanced. The associated standard deviation decreases by a factor of 4, while the resolution of the 0.662 MeV photopeak, is kept within detector characteristics.

da Costa, P. C. L.; Dantas, C. C.; Lira, C. A. B. O.; dos Santos, V. A.

2004-11-01

263

Compton scattering artifacts in electron excited X-ray spectra measured with a silicon drift detector.  

PubMed

Artifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present. PMID:22067917

Ritchie, Nicholas W M; Newbury, Dale E; Lindstrom, Abigail P

2011-12-01

264

The Development of High-Resolution Calorimetric X-Ray Detectors for Compton Scattering Experiments.  

NASA Astrophysics Data System (ADS)

Compton scattering is a means of probing electron momentum distributions and can be used to evaluate calculations of electron wavefunctions in solids. The need for improved resolution in Compton experiments performed with high energy x-rays has motivated the development of a high resolution spectrometer. Calorimetric x-ray detectors, produced at Goddard Space Flight Center for x-rays around 6 KeV, have been adapted for use in Compton scattering research using synchrotron radiation near 40 KeV. Such detectors are operated below 0.1 K and work by measuring the temperature increase which results from the absorption of a single x-ray photon. Seeking to optimize detector efficiency and response at high energies, a number of materials were investigated as candidates for the overlayer which is affixed to a device in order to absorb the x-rays and transfer their energy to phonons. Mercury-telluride and superconducting foils of rhenium, tantalum, and tin were studied, each producing a detector response very different from the others and from that expected from the Debye heat capacity of the material. Experiments with creating quasiparticle recombination sites on the superconductors to assist the thermalization process produced no measurable change in detector response. Using tin absorbers, a resolution of 90 eV at 32 KeV was achieved. The apparatus was brought to a wiggler beam line at the Stanford Synchrotron Radiation Laboratory, where Compton profiles of silicon for the (100) and (111) directions were measured. The difference between directional profiles was consistent with the previously measured anisotropy, but no new insights into the electronic structure of silicon were provided, owing to the low number of total counts and to a degradation in resolution experienced during operation at the synchrotron. This experiment illustrated the feasibility of using such a system for Compton scattering research. It is expected that future improvements to the detectors and to the supporting apparatus will make higher resolution measurements possible. A better understanding of the physics of the thermalization of x-rays in superconductors is required. The dissertation discusses some simple models to explain the observed performance of the superconducting absorbers and outlines a plan for further investigation.

Stahle, Caroline Kilbourne

265

Compton Scattering by Static and Moving Media. Part 1; The Transfer Equation and its Moments  

NASA Technical Reports Server (NTRS)

Compton scattering of photons by nonrelativistic particles is thought to play an important role in forming the radiation spectrum of many astrophysical systems. Here we derive the time-dependent photon kinetic equation that describes spontaneous and induced Compton scattering, as well as absorption and emission by static and moving media, the corresponding radiative transfer equation, and their zeroth and first angular moments, both in the system frame and in the frame comoving with the medium. We show that it is necessary to use the correct relativistic differential scattering cross section in order to obtain a photon kinetic equation that is correct to first order in Epsilon/m(sub e), T(sub e)/m(sub e), and V, where Epsilon is the photon energy, T(sub e) and m(sub e) are the electron temperature and rest mass, and V is the electron bulk velocity in units of the speed of light. We also demonstrate that the terms in the radiative transfer equation that are second order in V should usually be retained, because if the radiation energy density is sufficiently large, compared to the radiation flux, the effects of bulk Comptonization described by the terms that are second order in V can be as important as the effects described by the terms that are first order in V, even when V is small. The system- and fluid-frame equations that we derive are correct to first order in Epsilon/m(sub e). Our system-frame equations, which are correct to second order in V, may be used when V is not too large. Our fluid-frame equations, which are exact in V, may be used when V approaches 1. Both sets of equations are valid for systems of arbitrary optical depth and can therefore be used in both the free-streaming and diffusion regimes. We demonstrate that Comptonization by the electron bulk motion occurs whether or not the radiation field is isotropic or the bulk flow converges and that it is more important than thermal Comptonization if V(sup 2) is greater than 3T(sub e)/m(sub e).

Psaltis, Dimitrios; Lamb, Frederick K.

1997-01-01

266

Modeling and Simulations on Scattered Gamma-Ray Imaging without Collimator  

SciTech Connect

Scattered radiation by Compton effect in emission imaging has been considered increasingly as active agent instead of being treated as noise and being rejected. In a recent proposal, scattered radiation emitted by the object under investigation and detected by a collimated gamma camera was shown to provide the capability to reconstruct the object in three dimensions. The acquisition of the scattered radiation with an uncollimated detector would enhance drastically sensitivity and resolution. This paper proposes a formal model for the image formation in this new imaging process. Monte-Carlo simulations validate the forward model and are used as data for numerical reconstruction.

Driol, Clemence [LPTM/CNRS UMR 8089/Universite de Cergy-Pontoise 2 rue Adolphe Chauvin, 95302 Cergy-Pontoise Cedex (France)

2007-11-26

267

Measurement of the proton structure function F 2 at low Q 2 in QED Compton scattering at HERA  

Microsoft Academic Search

The proton structure function F2(x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV2, and Bjorken x up to ?0.06, a region which has not been covered previously by inclusive

A. Aktas; V. Andreev; T. Anthonis; A. Asmone; A. Babaev; S. Backovic; J. Bähr; P. Baranov; E. Barrelet; W. Bartel; S. Baumgartner; J. Becker; M. Beckingham; O. Behnke; O. Behrendt; A. Belousov; Ch. Berger; N. Berger; T. Berndt; J. C. Bizot; J. Böhme; M.-O. Boenig; V. Boudry; J. Bracinik; V. Brisson; H.-B. Bröker; D. P. Brown; D. Bruncko; F. W. Büsser; A. Bunyatyan; G. Buschhorn; L. Bystritskaya; A. J. Campbell; S. Caron; F. Cassol-Brunner; K. Cerny; V. Chekelian; C. Collard; J. G. Contreras; Y. R. Coppens; J. A. Coughlan; B. E. Cox; G. Cozzika; J. Cvach; J. B. Dainton; W. D. Dau; K. Daum; B. Delcourt; R. Demirchyan; A. De Roeck; K. Desch; E. A. De Wolf; C. Diaconu; J. Dingfelder; V. Dodonov; A. Dubak; C. Duprel; G. Eckerlin; V. Efremenko; S. Egli; R. Eichler; F. Eisele; M. Ellerbrock; E. Elsen; M. Erdmann; W. Erdmann; P. J. W. Faulkner; L. Favart; A. Fedotov; R. Felst; J. Ferencei; M. Fleischer; P. Fleischmann; Y. H. Fleming; G. Flucke; G. Flügge; A. Fomenko; I. Foresti; J. Formánek; G. Franke; G. Frising; E. Gabathuler; K. Gabathuler; E. Garutti; J. Garvey; J. Gayler; R. Gerhards; C. Gerlich; S. Ghazaryan; L. Goerlich; N. Gogitidze; S. Gorbounov; C. Grab; H. Grässler; T. Greenshaw; M. Gregori; G. Grindhammer; C. Gwilliam; D. Haidt; L. Hajduk; J. Haller; M. Hansson; G. Heinzelmann; R. C. W. Henderson; H. Henschel; O. Henshaw; R. Heremans; G. Herrera; I. Herynek; R.-D. Heuer; M. Hildebrandt; K. H. Hiller; P. Höting; D. Hoffmann; R. Horisberger; A. Hovhannisyan; M. Ibbotson; M. Ismail; M. Jacquet; L. Janauschek; X. Janssen; V. Jemanov; L. Jönsson; D. P. Johnson; H. Jung; D. Kant; M. Kapichine; M. Karlsson; J. Katzy; N. Keller; J. Kennedy; I. R. Kenyon; C. Kiesling; M. Klein; C. Kleinwort; T. Klimkovich; T. Kluge; G. Knies; A. Knutsson; B. Koblitz; V. Korbel; P. Kostka; R. Koutouev; A. Kropivnitskaya; J. Kroseberg; J. Kückens; T. Kuhr; M. P. J. Landon; W. Lange; T. Laštovi?ka; P. Laycock; A. Lebedev; B. Leißner; R. Lemrani; V. Lendermann; S. Levonian; L. Lindfeld; K. Lipka; B. List; E. Lobodzinska; N. Loktionova; R. Lopez-Fernandez; V. Lubimov; H. Lueders; D. Lüke; T. Lux; L. Lytkin; A. Makankine; N. Malden; E. Malinovski; S. Mangano; P. Marage; J. Marks; R. Marshall; M. Martisikova; H.-U. Martyn; S. J. Maxfield; D. Meer; A. Mehta; K. Meier; A. B. Meyer; H. Meyer; J. Meyer; S. Michine; S. Mikocki; I. Milcewicz-Mika; D. Milstead; A. Mohamed; F. Moreau; A. Morozov; I. Morozov; J. V. Morris; M. U. Mozer; K. Müller; P. Murín; V. Nagovizin; B. Naroska; J. Naumann; Th. Naumann; P. R. Newman; C. Niebuhr; A. Nikiforov; D. Nikitin; G. Nowak; M. Nozicka; R. Oganezov; B. Olivier; J. E. Olsson; G. Ossoskov; D. Ozerov; C. Pascaud; G. D. Patel; M. Peez; E. Perez; A. Perieanu; A. Petrukhin; D. Pitzl; R. Pla?akyt?; R. Pöschl; B. Portheault; B. Povh; N. Raicevic; Z. Ratiani; P. Reimer; B. Reisert; A. Rimmer; C. Risler; E. Rizvi; P. Robmann; B. Roland; R. Roosen; A. Rostovtsev; Z. Rurikova; S. Rusakov; K. Rybicki; D. P. C. Sankey; E. Sauvan; S. Schätzel; J. Scheins; F.-P. Schilling; P. Schleper; S. Schmidt; S. Schmitt; M. Schneider; L. Schoeffel; A. Schöning; V. Schröder; H.-C. Schultz-Coulon; C. Schwanenberger; K. Sedlák; F. Sefkow; I. Sheviakov; L. N. Shtarkov; Y. Sirois; T. Sloan; P. Smirnov; Y. Soloviev; D. South; V. Spaskov; A. Specka; H. Spitzer; R. Stamen; B. Stella; J. Stiewe; I. Strauch; U. Straumann; V. Tchoulakov; G. Thompson; P. D. Thompson; F. Tomasz; D. Traynor; P. Truöl; G. Tsipolitis; I. Tsurin; J. Turnau; E. Tzamariudaki; A. Uraev; M. Urban; A. Usik; D. Utkin; S. Valkár; A. Valkárová; C. Vallée; P. Van Mechelen; N. Van Remortel; A. Vargas Trevino; Y. Vazdik; C. Veelken; A. Vest; S. Vinokurova; V. Volchinski; K. Wacker; J. Wagner; G. Weber; R. Weber; D. Wegener; C. Werner; N. Werner; M. Wessels; B. Wessling; G.-G. Winter; Ch. Wissing; E.-E. Woehrling; R. Wolf; E. Wünsch; S. Xella; W. Yan; V. Yeganov; J. Žá?ek; J. Zálešák; Z. Zhang; A. Zhokin; H. Zohrabyan; F. Zomer

2004-01-01

268

Measurement of the proton structure function F2 at low Q2 in QED Compton scattering at HERA  

Microsoft Academic Search

The proton structure function F2(x,Q2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q2, down to 0.5 GeV2, and Bjorken x up to ˜0.06, a region which has not been covered previously by inclusive

A. Aktas; V. Andreev; T. Anthonis; A. Asmone; A. Babaev; S. Backovic; J. Bähr; P. Baranov; E. Barrelet; W. Bartel; S. Baumgartner; J. Becker; M. Beckingham; O. Behnke; O. Behrendt; A. Belousov; Ch. Berger; N. Berger; T. Berndt; J. C. Bizot; J. Böhme; M.-O. Boenig; V. Boudry; J. Bracinik; V. Brisson; H.-B. Bröker; D. P. Brown; D. Bruncko; F. W. Büsser; A. Bunyatyan; G. Buschhorn; L. Bystritskaya; A. J. Campbell; S. Caron; F. Cassol-Brunner; K. Cerny; V. Chekelian; C. Collard; J. G. Contreras; Y. R. Coppens; J. A. Coughlan; B. E. Cox; G. Cozzika; J. Cvach; J. B. Dainton; W. D. Dau; K. Daum; B. Delcourt; R. Demirchyan; A. de Roeck; K. Desch; E. A. de Wolf; C. Diaconu; J. Dingfelder; V. Dodonov; A. Dubak; C. Duprel; G. Eckerlin; V. Efremenko; S. Egli; R. Eichler; F. Eisele; M. Ellerbrock; E. Elsen; M. Erdmann; W. Erdmann; P. J. W. Faulkner; L. Favart; A. Fedotov; R. Felst; J. Ferencei; M. Fleischer; P. Fleischmann; Y. H. Fleming; G. Flucke; G. Flügge; A. Fomenko; I. Foresti; J. Formánek; G. Franke; G. Frising; E. Gabathuler; K. Gabathuler; E. Garutti; J. Garvey; J. Gayler; R. Gerhards; C. Gerlich; S. Ghazaryan; L. Goerlich; N. Gogitidze; S. Gorbounov; C. Grab; H. Grässler; T. Greenshaw; M. Gregori; G. Grindhammer; C. Gwilliam; D. Haidt; L. Hajduk; J. Haller; M. Hansson; G. Heinzelmann; R. C. W. Henderson; H. Henschel; O. Henshaw; R. Heremans; G. Herrera; I. Herynek; R.-D. Heuer; M. Hildebrandt; K. H. Hiller; P. Höting; D. Hoffmann; R. Horisberger; A. Hovhannisyan; M. Ibbotson; M. Ismail; M. Jacquet; L. Janauschek; X. Janssen; V. Jemanov; L. Jönsson; D. P. Johnson; H. Jung; D. Kant; M. Kapichine; M. Karlsson; J. Katzy; N. Keller; J. Kennedy; I. R. Kenyon; C. Kiesling; M. Klein; C. Kleinwort; T. Klimkovich; T. Kluge; G. Knies; A. Knutsson; B. Koblitz; V. Korbel; P. Kostka; R. Koutouev; A. Kropivnitskaya; J. Kroseberg; J. Kückens; T. Kuhr; M. P. J. Landon; W. Lange; T. Lastovicka; P. Laycock; A. Lebedev; B. Leißner; R. Lemrani; V. Lendermann; S. Levonian; L. Lindfeld; K. Lipka; B. List; E. Lobodzinska; N. Loktionova; R. Lopez-Fernandez; V. Lubimov; H. Lueders; D. Lüke; T. Lux; L. Lytkin; A. Makankine; N. Malden; E. Malinovski; S. Mangano; P. Marage; J. Marks; R. Marshall; M. Martisikova; H.-U. Martyn; S. J. Maxfield; D. Meer; A. Mehta; K. Meier; A. B. Meyer; H. Meyer; J. Meyer; S. Michine; S. Mikocki; I. Milcewicz-Mika; D. Milstead; A. Mohamed; F. Moreau; A. Morozov; I. Morozov; J. V. Morris; M. U. Mozer; K. Müller; P. Murín; V. Nagovizin; B. Naroska; J. Naumann; Th. Naumann; P. R. Newman; C. Niebuhr; A. Nikiforov; D. Nikitin; G. Nowak; M. Nozicka; R. Oganezov; B. Olivier; J. E. Olsson; G. Ossoskov; D. Ozerov; C. Pascaud; G. D. Patel; M. Peez; E. Perez; A. Perieanu; A. Petrukhin; D. Pitzl; R. Placakyte; R. Pöschl; B. Portheault; B. Povh; N. Raicevic; Z. Ratiani; P. Reimer; B. Reisert; A. Rimmer; C. Risler; E. Rizvi; P. Robmann; B. Roland; R. Roosen; A. Rostovtsev; Z. Rurikova; S. Rusakov; K. Rybicki; D. P. C. Sankey; E. Sauvan; S. Schätzel; J. Scheins; F.-P. Schilling; P. Schleper; S. Schmidt; S. Schmitt; M. Schneider; L. Schoeffel; A. Schöning; V. Schröder; H.-C. Schultz-Coulon; C. Schwanenberger; K. Sedlák; F. Sefkow; I. Sheviakov; L. N. Shtarkov; Y. Sirois; T. Sloan; P. Smirnov; Y. Soloviev; D. South; V. Spaskov; A. Specka; H. Spitzer; R. Stamen; B. Stella; J. Stiewe; I. Strauch; U. Straumann; V. Tchoulakov; G. Thompson; P. D. Thompson; F. Tomasz; D. Traynor; P. Truöl; G. Tsipolitis; I. Tsurin; J. Turnau; E. Tzamariudaki; A. Uraev; M. Urban; A. Usik; D. Utkin; S. Valkár; A. Valkárová; C. Vallée; P. van Mechelen; N. van Remortel; A. Vargas Trevino; Y. Vazdik; C. Veelken; A. Vest; S. Vinokurova; V. Volchinski; K. Wacker; J. Wagner; G. Weber; R. Weber; D. Wegener; C. Werner; N. Werner; M. Wessels; B. Wessling; G.-G. Winter; Ch. Wissing; E.-E. Woehrling; R. Wolf; E. Wünsch; S. Xella; W. Yan; V. Yeganov; J. Zácek; J. Zálesák; Z. Zhang; A. Zhokin; H. Zohrabyan; F. Zomer

2004-01-01

269

Evaluation of a stochastic reconstruction algorithm for use in Compton camera imaging and beam range verification from secondary gamma emission during proton therapy  

PubMed Central

In this paper, we study the feasibility of using the stochastic origin ensemble (SOE) algorithm for reconstructing images of secondary gammas emitted during proton radiotherapy from data measured with a three-stage Compton camera. The purpose of this study was to evaluate the quality of the images of the gamma rays emitted during proton irradiation produced using the SOE algorithm and to measure how well the images reproduce the distal falloff of the beam. For our evaluation, we performed a Monte Carlo simulation of an ideal three-stage Compton camera positioned above and orthogonal to a proton pencil beam irradiating a tissue phantom. Scattering of beam protons with nuclei in the phantom produces secondary gamma rays, which are detected by the Compton camera and used as input to the SOE algorithm. We studied the SOE reconstructed images as a function of the number of iterations, the voxel probability parameter, and the number of detected gammas used by the SOE algorithm. We quantitatively evaluated the capabilities of the SOE algorithm by calculating and comparing the normalized mean square error (NMSE) of SOE reconstructed images. We also studied the ability of the SOE reconstructed images to predict the distal falloff of the secondary gamma production in the irradiated tissue. Our results show that the images produced with the SOE algorithm converge in ~10,000 iterations, with little improvement to the image NMSE for iterations above this number. We found that the statistical noise of the images is inversely proportional to the ratio of the number of gammas detected to the SOE voxel probability parameter value. In our study, the SOE predicted distal falloff of the reconstructed images agrees with the Monte Carlo calculated distal falloff of the gamma emission profile in the phantom to within ±0.6 mm for the positions of maximum emission (100%) and 90%, 50%, and 20% distal falloff of the gamma emission profile. We conclude that the SOE algorithm is an effective method for reconstructing images of a proton pencil beam from the data collected by an ideal Compton camera and that these images accurately model the distal falloff of secondary gamma emission during proton irradiation.

Mackin, Dennis; Peterson, Steve; Beddar, Sam; Polf, Jerimy

2012-01-01

270

A 3D point-kernel multiple scatter model for parallel-beam SPECT based on a gamma-ray buildup factor  

Microsoft Academic Search

A three-dimensional (3D) point-kernel multiple scatter model for point spread function (PSF) determination in parallel-beam single-photon emission computed tomography (SPECT), based on a dose gamma-ray buildup factor, is proposed. This model embraces nonuniform attenuation in a voxelized object of imaging (patient body) and multiple scattering that is treated as in the point-kernel integration gamma-ray shielding problems. First-order Compton scattering is

Predrag Marinkovic; Radovan Ilic; Rajko Spaic

2007-01-01

271

Dissecting deuteron Compton scattering I: The observables with polarised initial states  

NASA Astrophysics Data System (ADS)

A complete set of linearly independent observables in Compton scattering with arbitrarily polarised real photons off an arbitrarily polarised spin-1 target is introduced, for the case that the final-state polarisations are not measured. Adopted from the one widely used, e.g., in deuteron photo-dissociation, it consists of 18 terms: the unpolarised cross section, the beam asymmetry, 4 target asymmetries and 12 asymmetries in which both beam and target are polarised. They are expressed by the helicity amplitudes and —where available— related to observables discussed by other authors. As application to deuteron Compton scattering, their dependence on the (isoscalar) scalar and spin dipole polarisabilities of the nucleon is explored in Chiral Effective Field Theory with dynamical ?(1232) degrees of freedom at order e 2 ? 3. Some asymmetries are sensitive to only one or two dipole polarisabilities, making them particularly attractive for experimental studies. At a photon energy of 100 MeV, a set of 5 observables is identified from which one may be able to extract the spin polarisabilities of the nucleon. These are experimentally realistic but challenging and mostly involve tensor-polarised deuterons. Relative to Compton scattering from a nucleon, sensitivity to the "mixed" spin polarisabilities ? E1 M2 and ? M1 E2 is increased because of the interference with the D wave component of the deuteron and with its pion-exchange current. An interactive Mathematica 9.0 notebook with results for all observables at photon energies up to 120 MeV is available from hgrie@gwu.edu.

Grießhammer, Harald W.

2013-08-01

272

Predictive powers of chiral perturbation theory in Compton scattering off protons  

NASA Astrophysics Data System (ADS)

We study low-energy nucleon Compton scattering in the framework of baryon chiral perturbation theory (B ?PT) with pion, nucleon, and ?(1232) degrees of freedom, up to and including the next-to-next-to-leading order (NNLO). We include the effects of order p 2, p 3, and p 4/ ?, with ??300 MeV the ?-resonance excitation energy. These are all “predictive” powers in the sense that no unknown low-energy constants enter until at least one order higher (i.e., p 4). Estimating the theoretical uncertainty on the basis of natural size for p 4 effects, we find that uncertainty of such a NNLO result is comparable to the uncertainty of the present experimental data for low-energy Compton scattering. We find an excellent agreement with the experimental cross-section data up to at least the pion-production threshold. Nevertheless, for the proton’s magnetic polarizability we obtain a value of (4.0±0.7)×10-4 fm3, in significant disagreement with the current PDG value. Unlike the previous ?PT studies of Compton scattering, we perform the calculations in a manifestly Lorentz-covariant fashion, refraining from the heavy-baryon (HB) expansion. The difference between the lowest order HB ?PT and B ?PT results for polarizabilities is found to be appreciable. We discuss the chiral behavior of proton polarizabilities in both HB ?PT and B ?PT with the hope to confront it with lattice QCD calculations in a near future. In studying some of the polarized observables we identify the regime where their naive low-energy expansion begins to break down, thus addressing the forthcoming precision measurements at the HIGS facility.

Lensky, Vadim; Pascalutsa, Vladimir

2010-01-01

273

AN INVERSE COMPTON SCATTERING ORIGIN OF X-RAY FLARES FROM Sgr A*  

SciTech Connect

The X-ray and near-IR emission from Sgr A* is dominated by flaring, while a quiescent component dominates the emission at radio and submillimeter (sub-mm) wavelengths. The spectral energy distribution of the quiescent emission from Sgr A* peaks at sub-mm wavelengths and is modeled as synchrotron radiation from a thermal population of electrons in the accretion flow, with electron temperatures ranging up to {approx}5-20 MeV. Here, we investigate the mechanism by which X-ray flare emission is produced through the interaction of the quiescent and flaring components of Sgr A*. The X-ray flare emission has been interpreted as inverse Compton, self-synchrotron Compton, or synchrotron emission. We present results of simultaneous X-ray and near-IR observations and show evidence that X-ray peak flare emission lags behind near-IR flare emission with a time delay ranging from a few to tens of minutes. Our inverse Compton scattering modeling places constraints on the electron density and temperature distributions of the accretion flow and on the locations where flares are produced. In the context of this model, the strong X-ray counterparts to near-IR flares arising from the inner disk should show no significant time delay, whereas near-IR flares in the outer disk should show a broadened and delayed X-ray flare.

Yusef-Zadeh, F. [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States); Wardle, M. [Department of Physics and Astronomy, Macquarie University, Sydney NSW 2109 (Australia); Dodds-Eden, K.; Gillessen, S.; Genzel, R. [Max Planck Institut fuer Extraterrestrische Physik, Postfach 1312, D-85741 Garching (Germany); Heinke, C. O. [Department of Physics, University of Alberta, 4-183 CCIS, Edmonton, AB T6G 2E1 (Canada); Bushouse, H. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Grosso, N.; Porquet, D. [Observatoire astronomique de Strasbourg, Universite de Strasbourg, CNRS, INSU, 11 rue de l'Universite, 67000 Strasbourg (France)

2012-07-15

274

Compton Scattering off Polarized Electrons with a High Finesse Fabry-Perot Cavity at JLAB  

SciTech Connect

We built and commissioned a new type of Compton polarimeter to measure the electron beam polarization at the Thomas Jefferson National Accelerator Facility (Virginia, USA). The heart of this polarimeter is a high-finesse monolithic Fabry-Perot cavity. Its purpose is to amplify a primary 300 mW laser beam in order to improve the signal to noise ratio of the polarimeter. It is the first time that a high-finesse Fabry-Perot cavity is enclosed in the vacuum of a particle accelerator to monitor the beam polarization by Compton polarimetry. The measured finesse and amplification gain of the cavity are F=26000 and G=7300. The electron beam crosses this high-power photon source at an angle of 23 mrad in the middle of the cavity where the photon beam power density is estimated to be 0.85MW/cm2. We have used this facility during the HAPPEX experiment (April-July 1999) and we give a preliminary measurement of Compton scattering asymmetry.

Nicholas Falletto; M. Authier; G. Bardin; Maud Baylac; M. Boyer; F. Bugeon; Etienne Burtin; Christian Cavata; N. Colombel; G. Congretel; R. Coquillard; G. Coulloux; B. Couzy; P. Deck; A. Delbart; D. Desforges; A. Donati; B. Duboue; Stephanie Escoffier; F. Farci; Bernard Frois; P. Girardot; J. Guillotau; C. Henriot; J. Jardillier; C. Jeanney; M. Juillard; J.P. Jorda; P. Legou; David Lhuillier; Y. Lussignol; P. Mangeot; X. Martin; F. Marie; Jacques Martino; M. Maurier; B. Mazeau; J.F. Millot; F. Molinie; J.P. Mols; J.P. Mouly; M. Mur; Damian Neyret; T. Pedrol; Stephane Platchkov; G. Pontet; Thierry Pussieux; Y. Queinec; P. Rebourgeard; J.C. Sellier; G. Tarte; C. Veyssiere; A. Zakharian; Pierre Bertin; Joseph Mitchell; J.M. Mackowski; L. Pinard

2000-08-01

275

Two-Dimensional Measurements of X-ray Spectra Generated by Laser-Compton Scattering  

NASA Astrophysics Data System (ADS)

Measurements of X-ray spectra generated by laser-Compton scattering are described. Basically, laser-Compton X-rays present distinctive characteristics, such as good-directivity, tunability, and a quasi-monochromatic X-ray spectrum. However, the actual X-ray spectrum is degraded by the effects of the broad spectrum of the laser pulse, and by the intrinsic spatial divergence of the electron bunch defined by the beam emittance. It is important to measure the spectral properties of laser-Compton X-rays for applications involving protein crystallography or mammography. The energy distribution in the forward direction can be observed using a front-illuminated deep-depletion X-ray charge-coupled device (CCD) detector. The spectral width of the measured X-rays within a detection angle of 4 mrad is estimated to be 5.0% (rms) for a CCD resolution of 2.6% (rms). These results can be accurately explained using a simple relationship between the electrons and the laser beam parameters.

Yanagida, Tatsuya; Nakajyo, Terunobu; Yorozu, Masafumi; Ito, Shinji; Sakai, Fumio

2007-01-01

276

Development of high-brightness hard x-ray source by Laser-Compton scattering  

NASA Astrophysics Data System (ADS)

Laser-Compton scattering is a promising method for generating high-brightness, ultrashort, energy-tunable X-rays. We have developed a compact X-ray source using laser-Compton scattering. Hard X-rays, ranging from 15 keV to 34 keV, were generated with a low-emittance, 38 MeV, 0.8 nC electron accelerator and a femtosecond 4TW Ti:sapphire laser. The created X-rays were composed of 2×106 (5×105) photons/pulse for interaction angles between an electron bunch and a laser pulse of 165° (90°). A highly accurate timing synchronization scheme was employed, and the fluctuation of the generated X-rays was suppressed to 11% (rms) for the 90° scattering. The spatial (angular) distributions for the intensity and the energy of the generated X-ray were measured, and agreed well with theoretical calculations. Thus, X-ray imaging has been demonstrated using a phase-contrast technique with the interference of an X-ray beam.

Yanagida, Tatsuya; Nakajyo, Terunobu; Ito, Shinji; Sakai, Fumio

2005-08-01

277

Deeply virtual Compton scattering on a photon and generalized parton distributions in the photon  

NASA Astrophysics Data System (ADS)

We consider deeply virtual Compton scattering on a photon target, in the generalized Bjorken limit, at the Born order and in the leading logarithmic approximation. We interpret the result as a factorized amplitude of a hard process described by handbag diagrams and anomalous generalized parton distributions in the photon. This anomalous part, with its characteristic log(Q) dependence, is present both in the DGLAP and in the ERBL regions. As a consequence, these generalized parton distributions of the photon obey DGLAP-ERBL evolution equations with an inhomogeneous term.

Friot, S.; Pire, B.; Szymanowski, L.

2007-02-01

278

Time evolution analysis of the electron distribution in Thomson/Compton back-scattering  

NASA Astrophysics Data System (ADS)

We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.

Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R.

2013-07-01

279

Kinetic energy of hydrogen in. beta. -V sub 2 H studied by neutron Compton scattering  

SciTech Connect

Hydrogen dissolves in nearly all metals in large quantities, occupying interstitial sites which are energetic minima of the hydrogen potential. Experimentally, this potential can be determined by neutron vibrational spectroscopy (NVS) and, recently, by neutron Compton scattering (NCS) i.e. either by a measurement of the excitation energies of the localized hydrogen vibrations or by a measurement of the hydrogen momentum distribution. In this brief communication we report on what we believe is the first NCS experiment on a metal hydride. For the system to be investigated we chose {beta}-V{sub 2}H, an ordered hydride phase with hydrogen on pseudotetragonal octahedral sites. 3 figs., 7 refs.

Hempelmann, R.; Richter, D. (Forschungszentrum Juelich GmbH (Germany, F.R.). Inst. fuer Festkoerperforschung); Price, D.L. (Argonne National Lab., IL (USA))

1990-08-01

280

Compton Scattering on the Proton and Light Nuclei in the ?-RESONANCE Region  

NASA Astrophysics Data System (ADS)

A microscopic coupled-channels model for Compton and pion scattering off the nucleon is introduced which is applicable at the lowest energies (polarizabilities) as well as at GeV energies. To introduce the model first the conventional K-matrix approach is discussed to extend this in a following chapter to the "Dressed K-Matrix" model. The latter approach restores causality, or analyticity, of the amplitude to a large extent. In particular, crossing symmetry, gauge invariance and unitarity are satisfied. The extent of violation of analyticity (causality) is used as an expansion parameter.

Scholten, O.; Kondratyuk, S.

2002-06-01

281

Compton-Scattering Cross Section on the Proton at High Momentum Transfer  

NASA Astrophysics Data System (ADS)

Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s=5 11 and -t=2 7GeV2 with a statistical accuracy of a few percent. The scaling power for the s dependence of the cross section at fixed center-of-mass angle was found to be 8.0±0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross-section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark.

Danagoulian, A.; Mamyan, V. H.; Roedelbronn, M.; Aniol, K. A.; Annand, J. R. M.; Bertin, P. Y.; Bimbot, L.; Bosted, P.; Calarco, J. R.; Camsonne, A.; Chang, C. C.; Chang, T.-H.; Chen, J.-P.; Choi, Seonho; Chudakov, E.; Degtyarenko, P.; de Jager, C. W.; Deur, A.; Dutta, D.; Egiyan, K.; Gao, H.; Garibaldi, F.; Gayou, O.; Gilman, R.; Glamazdin, A.; Glashausser, C.; Gomez, J.; Hamilton, D. J.; Hansen, J.-O.; Hayes, D.; Higinbotham, D. W.; Hinton, W.; Horn, T.; Howell, C.; Hunyady, T.; Hyde, C. E.; Jiang, X.; Jones, M. K.; Khandaker, M.; Ketikyan, A.; Kubarovsky, V.; Kramer, K.; Kumbartzki, G.; Laveissière, G.; Lerose, J.; Lindgren, R. A.; Margaziotis, D. J.; Markowitz, P.; McCormick, K.; Meekins, D. G.; Meziani, Z.-E.; Michaels, R.; Moussiegt, P.; Nanda, S.; Nathan, A. M.; Nikolenko, D. M.; Nelyubin, V.; Norum, B. E.; Paschke, K.; Pentchev, L.; Perdrisat, C. F.; Piasetzky, E.; Pomatsalyuk, R.; Punjabi, V. A.; Rachek, I.; Radyushkin, A.; Reitz, B.; Roche, R.; Ron, G.; Sabatié, F.; Saha, A.; Savvinov, N.; Shahinyan, A.; Shestakov, Y.; Širca, S.; Slifer, K.; Solvignon, P.; Stoler, P.; Tajima, S.; Sulkosky, V.; Todor, L.; Vlahovic, B.; Weinstein, L. B.; Wang, K.; Wojtsekhowski, B.; Voskanyan, H.; Xiang, H.; Zheng, X.; Zhu, L.

2007-04-01

282

Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering  

NASA Astrophysics Data System (ADS)

We present the first measurements of the e?p?ep? cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q2 dependence (from 1.5 to 2.3GeV2) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q2. The helicity-independent cross section is also measured at Q2=2.3GeV2. We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation.

Camacho, C. Muñoz; Camsonne, A.; Mazouz, M.; Ferdi, C.; Gavalian, G.; Kuchina, E.; Amarian, M.; Aniol, K. A.; Beaumel, M.; Benaoum, H.; Bertin, P.; Brossard, M.; Chen, J.-P.; Chudakov, E.; Craver, B.; Cusanno, F.; de Jager, C. W.; Deur, A.; Feuerbach, R.; Fieschi, J.-M.; Frullani, S.; Garçon, M.; Garibaldi, F.; Gayou, O.; Gilman, R.; Gomez, J.; Gueye, P.; Guichon, P. A. M.; Guillon, B.; Hansen, O.; Hayes, D.; Higinbotham, D.; Holmstrom, T.; Hyde-Wright, C. E.; Ibrahim, H.; Igarashi, R.; Jiang, X.; Jo, H. S.; Kaufman, L. J.; Kelleher, A.; Kolarkar, A.; Kumbartzki, G.; Laveissière, G.; Lerose, J. J.; Lindgren, R.; Liyanage, N.; Lu, H.-J.; Margaziotis, D. J.; Meziani, Z.-E.; McCormick, K.; Michaels, R.; Michel, B.; Moffit, B.; Monaghan, P.; Nanda, S.; Nelyubin, V.; Potokar, M.; Qiang, Y.; Ransome, R. D.; Réal, J.-S.; Reitz, B.; Roblin, Y.; Roche, J.; Sabatié, F.; Saha, A.; Sirca, S.; Slifer, K.; Solvignon, P.; Subedi, R.; Sulkosky, V.; Ulmer, P. E.; Voutier, E.; Wang, K.; Weinstein, L. B.; Wojtsekhowski, B.; Zheng, X.; Zhu, L.

2006-12-01

283

Observation of stimulated Compton scattering from resonant electrons in a laser-produced plasma  

SciTech Connect

An experimental study of stimulated Compton scattering (SCS) from resonant electrons in a laser-produced plasma is reported. Up to 1.9 kJ of 350-nm laser light was used to irradiate 3-{mu}m-thick CH targets in 1.3 to 3.3-ns pulses at intensities up to 1.3{times}10{sup 15} W/cm{sup 2}. SCS was detected by making time-resolved measurements of the emission near 420 nm. The measurements are compared to the results of theoretical modeling.

Drake, R.P.; Baldis, H.A.; Berger, R.L.; Kruer, W.L.; Williams, E.A.; Estabrook, K.; Johnston, T.W.; Young, P.E. (Lawrence Livermore National Laboratory, Livermore, California 94550 (US) National Research Council, Ottawa, Ontario, Canada K1A0R6 KMS Fusion, Inc., Ann Arbor, Michigan 48105 Institut National de la Recherche Scientifique-Energie, Varennes, Quebec, Canada J3X1S2)

1990-01-22

284

Compton-scattering cross section on the proton at high momentum transfer.  

PubMed

Cross-section values for Compton scattering on the proton were measured at 25 kinematic settings over the range s=5-11 and -t=2-7 GeV2 with a statistical accuracy of a few percent. The scaling power for the s dependence of the cross section at fixed center-of-mass angle was found to be 8.0+/-0.2, strongly inconsistent with the prediction of perturbative QCD. The observed cross-section values are in fair agreement with the calculations using the handbag mechanism, in which the external photons couple to a single quark. PMID:17501338

Danagoulian, A; Mamyan, V H; Roedelbronn, M; Aniol, K A; Annand, J R M; Bertin, P Y; Bimbot, L; Bosted, P; Calarco, J R; Camsonne, A; Chang, C C; Chang, T-H; Chen, J-P; Choi, Seonho; Chudakov, E; Degtyarenko, P; de Jager, C W; Deur, A; Dutta, D; Egiyan, K; Gao, H; Garibaldi, F; Gayou, O; Gilman, R; Glamazdin, A; Glashausser, C; Gomez, J; Hamilton, D J; Hansen, J-O; Hayes, D; Higinbotham, D W; Hinton, W; Horn, T; Howell, C; Hunyady, T; Hyde, C E; Jiang, X; Jones, M K; Khandaker, M; Ketikyan, A; Kubarovsky, V; Kramer, K; Kumbartzki, G; Laveissière, G; Lerose, J; Lindgren, R A; Margaziotis, D J; Markowitz, P; McCormick, K; Meekins, D G; Meziani, Z-E; Michaels, R; Moussiegt, P; Nanda, S; Nathan, A M; Nikolenko, D M; Nelyubin, V; Norum, B E; Paschke, K; Pentchev, L; Perdrisat, C F; Piasetzky, E; Pomatsalyuk, R; Punjabi, V A; Rachek, I; Radyushkin, A; Reitz, B; Roche, R; Ron, G; Sabatié, F; Saha, A; Savvinov, N; Shahinyan, A; Shestakov, Y; Sirca, S; Slifer, K; Solvignon, P; Stoler, P; Tajima, S; Sulkosky, V; Todor, L; Vlahovic, B; Weinstein, L B; Wang, K; Wojtsekhowski, B; Voskanyan, H; Xiang, H; Zheng, X; Zhu, L

2007-04-13

285

Time evolution analysis of the electron distribution in Thomson/Compton back-scattering  

SciTech Connect

We present the time evolution of the energy distribution of a relativistic electron beam after the Compton back-scattering with a counter-propagating laser field, performed in the framework of the Quantum Electrodynamics, by means of the code CAIN. As the correct angular distribution of the spontaneous emission is accounted, the main effect is the formation of few stripes, followed by the diffusion of the more energetic particles toward lower values in the longitudinal phase space. The Chapman-Kolmogorov master equation gives results in striking agreement with the numerical ones. An experiment on the Thomson source at SPARC-LAB is proposed.

Petrillo, V.; Bacci, A.; Curatolo, C.; Maroli, C.; Serafini, L.; Rossi, A. R. [INFN-Universitá degli Studi Milano, Via Celoria, 16 20133 Milano (Italy)] [INFN-Universitá degli Studi Milano, Via Celoria, 16 20133 Milano (Italy)

2013-07-28

286

Timelike and spacelike deeply virtual Compton scattering at next-to-leading order  

NASA Astrophysics Data System (ADS)

We study timelike and spacelike virtual Compton scattering in the generalized Bjorken scaling regime at next-to-leading order in the strong coupling constant, in the medium energy range which will be studied intensely at JLab12 and in the COMPASS-II experiment at CERN. We show that the Born amplitudes get sizeable O(?s) corrections and, even at moderate energies, the gluonic contributions are by no means negligible. We stress that the timelike and spacelike cases are complementary and that their difference deserves much special attention.

Moutarde, H.; Pire, B.; Sabatié, F.; Szymanowski, L.; Wagner, J.

2013-03-01

287

Development of a three dimensional four mirror optical cavity for laser-Compton scattering  

NASA Astrophysics Data System (ADS)

This paper describes a design and performance of a three-dimensional 4-mirror optical cavity for development of intense photon sources by laser-Compton scattering. We achieved the finesse of 4000 and average power of 2.6 kW in the cavity with the vertical laser beam spot size of 13±1 ?m in ? at the laser-electron interaction point. As a result, we observed 124±1 photons with average energy of 24 MeV per beam crossing, which corresponds to the generation of 2.7×108 photons per second.

Akagi, T.; Araki, S.; Funahashi, Y.; Honda, Y.; Kataoka, H.; Kon, T.; Miyoshi, S.; Okugi, T.; Omori, T.; Sakaue, K.; Shimizu, H.; Takahashi, T.; Tanaka, R.; Terunuma, N.; Urakawa, J.; Washio, M.; Yoshitama, H.

2013-10-01

288

Determination of the number of pulsed laser-Compton scattering photons  

NASA Astrophysics Data System (ADS)

We measured pulse-height spectra of 16.7 MeV laser-Compton scattering photons with a 6 in.×5 in. NaI(Tl) detector for blank and three lead materials of 75.8, 50.9, and 25.9% transmissions at the NewSUBARU facility to investigate how the original Poisson distribution of the pulsed photons is modified after passing through thick-target materials. We present a well-prescribed method of determining the number of incident photons within 3.5% accuracy based on the response of the NaI(Tl) detector to the pulsed photon beams.

Kondo, Takeo; Utsunomiya, Hiroaki; Akimune, Hidetoshi; Yamagata, Tamio; Okamoto, Akiyuki; Harada, Hideo; Kitatani, Fumito; Shima, Tatsushi; Horikawa, Ken; Miyamoto, Shuji

2011-12-01

289

Observation of 1-10 MeV Gamma-Rays from the Crab with the Balloon-Borne LXeGRIT Compton Telescope  

NASA Astrophysics Data System (ADS)

The balloon-borne LXeGRIT is the first prototype of a novel Compton telescope based on a high resolution 3-D imaging time projection chamber (TPC). The ionization detector, triggered by the fast Xe scintillation light, measures the three spatial coordinates and the energy deposited by each gamma-ray interaction in its active volume of 2800 cm3 of pure liquid Xenon. As a calorimeter, LXeGRIT is sensitive in the energy range 0.1 - 10 MeV. For gamma-ray imaging, LXeGRIT relies on events with multiple Compton interactions, after their scattering sequence has been correctly reconstructed. Results from experiments with laboratory sources as well as results from the most recent balloon flight experiment have established the response of the instrument as a Compton imager and spectrometer in one detector. We present these results and summarize the performance of LXeGRIT in flight, with respect to the measurement of the background rate and to the imaging of the Crab Nebula in the 1-3 MeV band.

Aprile, E.; Curioni, A.; Giboni, K.-L.; Kobayashi, M.; Oberlack, U. G.; Chupp, E. L.; Dunphy, P. P.; Ventura, S.; Doke, T.; Kikuchi, J.

2003-03-01

290

Development of compact Compton gamma camera for non-destructive detection and location of hidden explosives with neutron induced prompt gamma-ray imaging  

Microsoft Academic Search

As a unique gamma-ray sensor for detection and location of hidden explosives with neutron induced prompt gamma-ray analysis, we are developing a compact and efficient Compton gamma camera based on stacked BGO scintillator rods to deduce the incident direction of characteristic 10.8 MeV gamma-rays produced from nitrogen abundant in explosives through neutron capture reaction. The detector unit consists of 5.4

T. Iguchi; J. Kawarabayashi; K. Watanabe; H. Kenjyo; A. Uritani

2005-01-01

291

Response of doped alkali iodides measured with gamma-ray absorption and Compton electrons  

NASA Astrophysics Data System (ADS)

Relative light yield and intrinsic energy resolution of NaI:Tl, CsI:Na and CsI:Tl crystals were investigated by means of the wide angle Compton coincidence technique in wide energy range from several keV up to 1 MeV. The experimental setup consisted of a high purity germanium (HPGe) detector and the tested scintillators were put at a close separation from the HPGe detector. The tested samples were cylinders of 25 mm diameter and height coupled to a photomultiplier. Compton electron responses were compared to the results obtained with ?-ray absorption peaks. A correlation between intrinsic resolution of the tested scintillation materials and their nonproportionality was observed. Substantial differences in intrinsic resolution measured for ?-ray absorption peaks and Compton electrons were registered in the energy range between 50 keV and 200 keV. The results were discussed in terms of electron scattering, pointing to ?-ray production as an important contribution for determination of scintillator intrinsic resolution.

Swiderski, Lukasz; Moszynski, Marek; Czarnacki, Wieslaw; Szawlowski, Marek; Szczesniak, Tomasz; Pausch, Guntram; Plettner, Cristina; Roemer, Katja; Schotanus, Paul

2013-03-01

292

Measurements of Compton Scattering on the Proton at 2 - 6 GeV  

SciTech Connect

Similar to elastic electron scattering, Compton Scattering on the proton at high momentum transfers(and high p?) can be an effective method to study its short-distance structure. An experiment has been carried out to measure the cross sections for Real Compton Scattering (RCS) on the proton for 2.3-5.7 GeV electron beam energies and a wide distribution of large scattering angles. The 25 kinematic settings sampled a domain of s = 5?11(GeV/c)2,?t = ?7(GeV/c)2 and ?u = 0.5?6.5(GeV/c)2. In addition, a measurement of longitudinal and transverse polarization transfer asymmetries was made at a 3.48 GeV beam energy and a scattering angle of ?cm = 120o. These measurements were performed to test the existing theoretical mechanisms for this process as well as to determine RCS form factors. At the heart of the scientific motivation is the desire to understand the manner in which a nucleon interacts with external excitations at the above listed energies, by comparing and contrasting the two existing models – Leading Twist Mechanism and Soft Overlap “Handbag” Mechanism – and identify the dominant mechanism. Furthermore, the Handbag Mechanism allows one to calculate reaction observables in the framework of Generalized Parton Distributions (GPD), which have the function of bridging the wide gap between the exclusive(form factors) and inclusive(parton distribution functions) description of the proton. The experiment was conducted in Hall A of Thomas Jefferson National Accelerator Facility(Jefferson Lab). It used a polarized and unpolarized electron beam, a 6% copper radiator with the thickness of 6.1% radiation lengths (to produce a bremsstrahlung photon beam), the Hall A liquid hydrogen target, a high resolution spectrometer with a focal plane polarimeter, and a photon hodoscope calorimeter. Results of the differential cross sections are presented, and discussed in the general context of the scientific motivation.

Areg Danagoulian

2006-05-01

293

Local Two-Photon Couplings and the J=0 Fixed Pole in Real and Virtual Compton Scattering  

SciTech Connect

The local coupling of two photons to the fundamental quark currents of a hadron gives an energy-independent contribution to the Compton amplitude proportional to the charge squared of the struck quark, a contribution which has no analog in hadron scattering reactions. We show that this local contribution has a real phase and is universal, giving the same contribution for real or virtual Compton scattering for any photon virtuality and skewness at fixed momentum transfer squared t. The t-dependence of this J = 0 fixed Regge pole is parameterized by a yet unmeasured even charge-conjugation form factor of the target nucleon. The t = 0 limit gives an important constraint on the dependence of the nucleon mass on the quark mass through the Weisberger relation. We discuss how this 1=x form factor can be extracted from high energy deeply virtual Compton scattering and examine predictions given by models of the H generalized parton distribution.

Brodsky, Stanley J.; Llanes-Estrada, Felipe J.; Szczepaniak, Adam P.

2008-12-05

294

Local two-photon couplings and the J=0 fixed pole in real and virtual Compton scattering  

SciTech Connect

The local coupling of two photons to the fundamental quark currents of a hadron gives an energy-independent contribution to the Compton amplitude proportional to the charge squared of the struck quark, a contribution which has no analog in hadron scattering reactions. We show that this local contribution has a real phase and is universal, giving the same contribution for real or virtual Compton scattering for any photon virtuality and skewness at fixed momentum transfer squared t. The t dependence of this J=0 fixed Regge pole is parameterized by a yet unmeasured even charge-conjugation form factor of the target nucleon. The t=0 limit gives an important constraint on the dependence of the nucleon mass on the quark mass through the Weisberger relation. We discuss how this 1/x form factor can be extracted from high-energy deeply virtual Compton scattering and examine predictions given by models of the H generalized parton distribution.

Brodsky, Stanley J.; Llanes-Estrada, Felipe J.; Szczepaniak, Adam P. [Theory Group, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, 94025 Menlo Park, California (United States); Departmento Fisica Teorica I, Facultad de Ciencias Fisicas, Universidad Complutense de Madrid, 28040 Madrid (Spain); Department of Physics and Nuclear Theory Center, Indiana University, Bloomington, Indiana 47405 (United States)

2009-02-01

295

Experiments in Special Relativity Using Compton Scattering of Gamma Rays.  

ERIC Educational Resources Information Center

Some simple undergraduate laboratory experiments are described, which verify the energy-momentum relationship of special relativity. These experiments have been designed either to be used as classroom demonstrations or to be carried out by second-year students. (Author/JN)

Egelstaff, P. A.; And Others

1981-01-01

296

Effects of incoherent and coherent scattering on the exposure buildup factors of low-energy gamma rays  

Microsoft Academic Search

The effects of including incoherent and coherent scattering in a calculation of the exposure buildup factors for plane normal gamma-ray sources have been investigated by using an electron-gamma-ray shower Monte Carlo code, EGS4, for water, iron, and lead in the 40- to 200-keV range. The ''true'' buildup factors for practical uses are defined to clarify the effects of bound-electron Compton

H. Hirayama; D. K. Trubey

1988-01-01

297

Stimulated Compton scattering in two-color ionization of hydrogen with keV electromagnetic fields.  

PubMed

We present a theoretical study of two-color ionization of hydrogen with keV photons at intensities ranging from 1016 to 1018??W/cm2. We consider the atom in interaction with a superposition of two electromagnetic pulses centered around two frequencies that differ by a few atomic units and we present in detail the case of the frequencies 55 and 50 a.u. We present the electron energy spectra, angular distributions, and ionization rates based on nonperturbative and perturbative calculations. Although the ejected electron energy distribution is dominated by one-photon ionization from each pulse, we are able to identify the contribution of stimulated Compton scattering, a process in which one photon is absorbed while the other is emitted, the photon energy difference being transferred to the electron. This leads to low-energy electrons, and we show in particular that it is of crucial importance to consider the retardation effects on the ionization rates and the electron angular distributions. The relative propagation direction of the two fields also plays an important role; in the case of counterpropagating fields, the ionization by stimulated Compton scattering is dominated by A2 and competes with one-photon ionization at high intensities. PMID:24579592

Bachau, H; Dondera, M; Florescu, V

2014-02-21

298

Stability analysis of implicit time discretizations for the Compton-scattering Fokker-Planck equation  

SciTech Connect

The Fokker-Planck equation is a widely used approximation for modeling the Compton scattering of photons in high energy density applications. In this paper, we perform a stability analysis of three implicit time discretizations for the Compton-Scattering Fokker-Planck equation. Specifically, we examine (i) a Semi-Implicit (SI) scheme that employs backward-Euler differencing but evaluates temperature-dependent coefficients at their beginning-of-time-step values, (ii) a Fully Implicit (FI) discretization that instead evaluates temperature-dependent coefficients at their end-of-time-step values, and (iii) a Linearized Implicit (LI) scheme, which is developed by linearizing the temperature dependence of the FI discretization within each time step. Our stability analysis shows that the FI and LI schemes are unconditionally stable and cannot generate oscillatory solutions regardless of time-step size, whereas the SI discretization can suffer from instabilities and nonphysical oscillations for sufficiently large time steps. With the results of this analysis, we present time-step limits for the SI scheme that prevent undesirable behavior. We test the validity of our stability analysis and time-step limits with a set of numerical examples.

Densmore, Jeffery D [Los Alamos National Laboratory; Warsa, James S [Los Alamos National Laboratory; Lowrie, Robert B [Los Alamos National Laboratory; Morel, Jim E [TEXAS A& M UNIV

2008-01-01

299

Understanding spin structure in metallacrown single-molecule magnets using magnetic compton scattering.  

PubMed

The 3d-4f mixed metallacrowns frequently show single-molecule magnetic behavior. We have used magnetic Compton scattering to characterize the spin structure and orbital interactions in three isostructural metallacrowns: Gd2Mn4, Dy2Mn4, and Y2Mn4. These data allow the direct determination of the spin only contribution to the overall magnetic moment. We find that the lanthanide 4f spin in Gd2Mn4 and Dy2Mn4 is aligned parallel to the Mn 3d spin. For Y2Mn4 (manganese-only spin) we find evidence for spin delocalization into the O 2p orbitals. Comparing the magnetic Compton scattering data with SQUID studies that measure the total magnetic moment suggests that Gd2Mn4 and Y2Mn4 have only a small orbital contribution to the moment. In contrast, the total magnetic moment for Dy2Mn4 MCs is much larger than the spin-only moment, demonstrating a significant orbital contribution to the overall magnetic moment. Overall, these data provide direct insight into the correlation of molecular design with molecular magnetic properties. PMID:24625070

Deb, Aniruddha; Boron, Thaddeus T; Itou, Masayoshi; Sakurai, Yoshiharu; Mallah, Talal; Pecoraro, Vincent L; Penner-Hahn, James E

2014-04-01

300

Testing Models of Resonant Compton Scattering in X-Ray Pulsars  

NASA Technical Reports Server (NTRS)

Over the performance period covered by the grant, the principal investigator modified a Monte Carlo Compton scattering code to model the propagation of x-rays through the magnetosphere of accreting neutron stars. These modifications were made to enable the author to compare the observations of x-ray pulsars to theoretical models of the system. The original code was designed to study relativistic plasmas with one of two geometries: a plane parallel plasma with a differential relativistic bulk velocity, and a static spherically symmetric plasma.- This code did not treat gravitational bending or bulk motion in the magnetosphere of a neutron star. Under the grant, the author incorporated code to trace light paths in a Schwarzschild metric. The code was modified to keep track of the photon polarization during propagati on. The investigator also modified the code so that bulk motion in an axisymmetric system is treated properly. An approximate treatment for resonant Compton scattering was added to the code. Finally, code was added that creates model observables that can be compared to observations, such as projected x-ray emission maps and energy-dependent light curves. Comparison to observations is now commencing.

Brainerd, Jerome J.

2000-01-01

301

The Simulation of AN Imaging Gamma-Ray Compton Backscattering Device Using GEANT4  

NASA Astrophysics Data System (ADS)

A gamma-backscattering imaging device dubbed Compton Camera, developed at GSI (Darmstadt, Germany) and modified and studied at the Nuclear Physics Group of the National University of Colombia in Bogotá, uses the back-to-back emission of two gamma rays in the positron annihilation to construct a bidimensional image that represents the distribution of matter in the field-of-view of the camera. This imaging capability can be used in a host of different situations, for example, to identify and study deposition and structural defects, and to help locating concealed objects, to name just two cases. In order to increase the understanding of the response of the Compton Camera and, in particular, its image formation process, and to assist in the data analysis, a simulation of the camera was developed using the GEANT4 simulation toolkit. In this work, the images resulting from different experimental conditions are shown. The simulated images and their comparison with the experimental ones already suggest methods to improve the present experimental device

Flechas, D.; Sarmiento, L. G.; Cristancho, F.; Fajardo, E.

2014-02-01

302

Low Noise Double-Sided Silicon Strip Detector for Multiple-Compton Gamma-ray Telescope  

SciTech Connect

A Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in an energy band 0.1-20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of the SMCT is the high energy resolution that is crucial for high angular resolution and high background rejection capability. We have developed prototype modules for a low noise Double-sided Silicon Strip Detector (DSSD) system which is an essential element of the SMCT. The geometry of the DSSD is optimized to achieve the lowest noise possible. A new front-end VLSI device optimized for low noise operation is also developed. We report on the design and test results of the prototype system. We have reached an energy resolution of 1.3 keV (FWHM) for 60 keV and 122 keV at 0 C.

Tajima, Hiroyasu

2002-12-03

303

QCD radiative corrections to the soft spectator contribution in the wide angle Compton scattering  

NASA Astrophysics Data System (ADS)

We derive the complete factorization formula for the leading power contribution in wide angle Compton scattering. It consists of the soft- and hard-spectator contributions. The hard-spectator contribution is well known and defined in the form of the convolution of a hard kernel with the nucleon distribution amplitudes. The soft-spectator contribution describes the scattering which involves the soft modes. We use the soft collinear effective theory in order to define this term in a field theoretical approach. Using the SCET framework we provide the proof of the factorization formula. We also compute the next-to-leading QCD corrections to the hard coefficient function of the soft spectator contribution and perform a phenomenological analysis of existing experimental data within the developed formalism.

Kivel, N.; Vanderhaeghen, M.

2014-06-01

304

Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays  

SciTech Connect

Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator.

Cipiccia, S.; Wiggins, S. M.; Brunetti, E.; Vieux, G.; Yang, X.; Welsh, G. H.; Anania, M.; Islam, M. R.; Ersfeld, B.; Jaroszynski, D. A. [Scottish Universities Physics Alliance, Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom)] [Scottish Universities Physics Alliance, Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom); Maneuski, D.; Montgomery, R.; Smith, G.; Hoek, M.; Hamilton, D. J.; Shea, V. O. [Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom)] [Scottish Universities Physics Alliance, School of Physics and Astronomy, University of Glasgow, Glasgow G12 8QQ (United Kingdom); Issac, R. C. [Scottish Universities Physics Alliance, Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom) [Scottish Universities Physics Alliance, Department of Physics, University of Strathclyde, John Anderson Building, 107 Rottenrow, Glasgow G4 0NG (United Kingdom); Research Department of Physics, Mar Athanasius College, Kothamangalam 686666, Kerala (India); Lemos, N. R. C.; Dias, J. M. [GoLP/Instituto de Plasmas eFusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal)] [GoLP/Instituto de Plasmas eFusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Symes, D. R. [Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, OX11 0QX Didcot (United Kingdom)] [Central Laser Facility, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, OX11 0QX Didcot (United Kingdom); and others

2013-11-15

305

Compton scattering for spectroscopic detection of ultra-fast, high flux, broad energy range X-rays  

NASA Astrophysics Data System (ADS)

Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator.

Cipiccia, S.; Wiggins, S. M.; Maneuski, D.; Brunetti, E.; Vieux, G.; Yang, X.; Issac, R. C.; Welsh, G. H.; Anania, M.; Islam, M. R.; Ersfeld, B.; Montgomery, R.; Smith, G.; Hoek, M.; Hamilton, D. J.; Lemos, N. R. C.; Symes, D. R.; Rajeev, P. P.; Shea, V. O.; Dias, J. M.; Jaroszynski, D. A.

2013-11-01

306

Quasi-free Compton scattering and the polarizabilities of the neutron  

NASA Astrophysics Data System (ADS)

Differential cross-sections for quasi-free Compton scattering from the proton and neutron bound in the deuteron have been measured using the Glasgow/Mainz photon tagging spectrometer at the Mainz MAMI accelerator together with the Mainz [48]cm ;SPMOslash; × [64]cm NaI(Tl) photon detector and the Göttingen SENECA recoil detector. The data cover photon energies ranging from [200]MeV to [400]MeV at ?LAB? = 136.2°. Liquid deuterium and hydrogen targets allowed direct comparison of free and quasi-free scattering from the proton. The neutron detection efficiency of the SENECA detector was measured via the reaction p(?,?+n). The ``free'' proton Compton scattering cross-sections extracted from the bound proton data are in reasonable agreement with those for the free proton which gives confidence in the method to extract the differential cross-section for free scattering from quasi-free data. Differential cross-sections on the free neutron have been extracted and the difference of the electromagnetic polarizabilities of the neutron has been determined to be ?n - ?n = 9.8+/-3.6(stat)+2.1-1.1(syst)+/-2.2(model) in units of [10-4]fm3. In combination with the polarizability sum ?n + ?n = 15.2+/-0.5 deduced from photoabsorption data, the neutron electric and magnetic polarizabilities, ?n = 12.5+/-1.8(stat)+1.1-0.6(syst)+/-1.1(model) and ?n = 2.7+/-1.8(stat)+0.6-1.1(syst)+/-1.1(model) are obtained. The backward spin polarizability of the neutron was determined to be ?(n)? = (58.6+/-4.0)×10-4fm4.

Kossert, K.; Camen, M.; Wissmann, F.; Ahrens, J.; Annand, J. R. M.; Arends, H.-J.; Beck, R.; Caselotti, G.; Grabmayr, P.; Jahn, O.; Jennewein, P.; Levchuk, M. I.; L'vov, A. I.; McGeorge, J. C.; Natter, A.; Olmos de León, V.; Petrun'kin, V. A.; Rosner, G.; Schumacher, M.; Seitz, B.; Smend, F.; Thomas, A.; Weihofen, W.; Zapadtka, F.

307

Compton scattering of an X-ray photon by an open-shell atom  

SciTech Connect

A nonrelativistic quantum theory for the nonresonant Compton scattering of an X-ray photon by a free many-electron atom with an open shell in the ground state has been constructed in the single-configuration Hartree-Fock approximation outside the impulse approximation widely used in the literature. The transition to an atom with closed shells reproduces the results obtained previously in [6, 7]. The results of a test calculation for atoms with open (Ti, Fe) and closed (Zn) 3d core shells are presented. The effects of the radial relaxation of one-electron states in the field of core vacancies have been taken into account. The results of the calculation agree well with the experimental results [15, 16]. It has been established that the results of the impulse approximation in the investigated X-ray photon energy ranges disagree with those of our theory not only quantitatively but also qualitatively. In particular, the impulse approximation near the elastic (Thomson and Rayleigh) scattering line leads to a gross overestimation of the contributions from the deep atomic shells involved in the inelastic photon scattering only virtually to the scattering probability. The presented theory is general in character and its applicability to a particular element of the Mendeleev table with an open core shell or to a many-electron atomic ion is limited only by the requirement that the nonrelativistic Hartree-Fock approximation be properly used in describing the scattering-state wave functions.

Hopersky, A. N., E-mail: hopersky_vm_1@rgups.ru; Nadolinsky, A. M. [Rostov State University of Transport Communication (Russian Federation)

2012-09-15

308

Compton scattering of an X-ray photon by an open-shell atom  

NASA Astrophysics Data System (ADS)

A nonrelativistic quantum theory for the nonresonant Compton scattering of an X-ray photon by a free many-electron atom with an open shell in the ground state has been constructed in the single-configuration Hartree-Fock approximation outside the impulse approximation widely used in the literature. The transition to an atom with closed shells reproduces the results obtained previously in [6, 7]. The results of a test calculation for atoms with open (Ti, Fe) and closed (Zn) 3 d core shells are presented. The effects of the radial relaxation of one-electron states in the field of core vacancies have been taken into account. The results of the calculation agree well with the experimental results [15, 16]. It has been established that the results of the impulse approximation in the investigated X-ray photon energy ranges disagree with those of our theory not only quantitatively but also qualitatively. In particular, the impulse approximation near the elastic (Thomson and Rayleigh) scattering line leads to a gross overestimation of the contributions from the deep atomic shells involved in the inelastic photon scattering only virtually to the scattering probability. The presented theory is general in character and its applicability to a particular element of the Mendeleev table with an open core shell or to a many-electron atomic ion is limited only by the requirement that the nonrelativistic Hartree-Fock approximation be properly used in describing the scattering-state wave functions.

Hopersky, A. N.; Nadolinsky, A. M.

2012-09-01

309

Segmentation of the body and lungs from Compton scatter and photopeak window data in SPECT: A Monte-Carlo investigation  

SciTech Connect

In SPECT imaging of the chest, nonuniform attenuation correction requires use of a patient specific attenuation ({mu}) map. Such a map can be obtained by estimating the regions of (1) the lungs and (2) the soft tissues and bones, and then assigning an appropriate value of attenuation coefficient ({mu}) to each region. The authors proposed a method to segment such regions from the Compton scatter and photopeak window SPECT slices of Tc-99m Sestamibi studies. The Compton scatter slices are used to segment the body outline and to estimate the regions of the lungs. Locations of the back bone and sternum are estimated from the photopeak window slices to assist in the segmentation. To investigate the accuracy of using Compton scatter slices in estimating the regions of the body and the lungs, a Monte-Carlo SPECT simulation of an anthropomorphic phantom with an activity distribution and noise characteristics similar to patient data was conducted. Energy windows of various widths were simulated for use in locating a suitable Compton scatter window for imaging. The effects of attenuation correction using a {mu} map based on segmentation were also studied.

Pan, T.S.; King, M.A.; Vries, D.J. de [Univ. of Massachusetts Medical Center, Worcester, MA (United States). Dept. of Nuclear Medicine; Ljungberg, M. [Univ. of Lund (Sweden). Dept. of Radiation Physics

1996-02-01

310

Ultra-Bright X-Ray Generation Using Inverse Compton Scattering of Picosecond CO(2) Laser Pulses.  

National Technical Information Service (NTIS)

Laser-Compton scattering with picosecond CO(sub 2) laser pulses is proposed for generation of high-brightness x-rays. The interaction chamber has been developed and the experiment is scheduled for the generation of the x-rays of 4.7 keV, 10(sub 7) photons...

A. Tsunemi A. Endo I. Pogorelsky I. Ben-Zvi K. Kusche J. Skaritka V. Yakimenko T. Hirose

1999-01-01

311

Low-noise double-sided silicon strip detector for multiple-compton gamma-ray telescope  

Microsoft Academic Search

The Semiconductor Multiple-Compton Telescope (SMCT) is being developed to explore the gamma-ray universe in an energy band 0.1--20 MeV, which is not well covered by the present or near-future gamma-ray telescopes. The key feature of the SMCT is the high energy resolution that is crucial for high angular resolution and high background rejection capability. We have developed prototype modules for

Hiroyasu Tajima; Tuneyoshi Kamae; Shingo Uno; Tatsuya Nakamoto; Yasushi Fukazawa; Takefumi Mitani; Tadayuki Takahashi; Kazuhiro Nakazawa; Yu Okada; Masaharu Nomachi

2003-01-01

312

A laser-Compton scattering prototype experiment at 100 MeV linac of Shanghai Institute of Applied Physics  

SciTech Connect

As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm and pulse width of 21 ns (full width at half maximum)] and electron bunches [with energy of 108 MeV and pulse width of 0.95 ns (rms)] at an angle of 42 deg. between laser and electron beam. In order to measure the energy spectrum of LCS x-rays, a Si(Li) detector along the electron beam line axis is positioned at 9.8 m away from a LCS chamber. After background subtraction, the LCS x-ray spectrum with the peak energy of 29.1{+-}4.4|{sub stat}{+-}2.1|{sub syst} keV and the peak width (rms) of 7.8{+-}2.8|{sub stat}{+-}0.4|{sub syst} keV is observed. Normally the 100 MeV linac operates with the electron macropulse charge of 1.0 nC/pulse, and the electron and laser collision repetition rate of 20 Hz. Therefore, the total LCS x-ray flux of (5.2{+-}2.0)x10{sup 2} Hz can be achieved.

Luo, W.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Xu, Y.; Yang, L. F. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Xu, W. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); University of Science and Technology of China, Hefei 230026 (China); Pan, Q. Y.; Cai, X. Z.; Chen, J. G.; Chen, Y. Z.; Guo, W.; Liu, W. H.; Lin, G. Q.; Ma, Y. G.; Shen, W. Q.; Xu, B. J.; Xu, J. Q.; Zhang, H. O.; Yan, Z. [Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800 (China); and others

2010-01-15

313

A laser-Compton scattering prototype experiment at 100 MeV linac of Shanghai Institute of Applied Physics.  

PubMed

As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm and pulse width of 21 ns (full width at half maximum)] and electron bunches [with energy of 108 MeV and pulse width of 0.95 ns (rms)] at an angle of 42 degrees between laser and electron beam. In order to measure the energy spectrum of LCS x-rays, a Si(Li) detector along the electron beam line axis is positioned at 9.8 m away from a LCS chamber. After background subtraction, the LCS x-ray spectrum with the peak energy of 29.1+/-4.4|(stat)+/-2.1|(syst) keV and the peak width (rms) of 7.8+/-2.8|(stat)+/-0.4|(syst) keV is observed. Normally the 100 MeV linac operates with the electron macropulse charge of 1.0 nC/pulse, and the electron and laser collision repetition rate of 20 Hz. Therefore, the total LCS x-ray flux of (5.2+/-2.0) x 10(2) Hz can be achieved. PMID:20113090

Luo, W; Xu, W; Pan, Q Y; Cai, X Z; Chen, J G; Chen, Y Z; Fan, G T; Fan, G W; Guo, W; Li, Y J; Liu, W H; Lin, G Q; Ma, Y G; Shen, W Q; Shi, X C; Xu, B J; Xu, J Q; Xu, Y; Zhang, H O; Yan, Z; Yang, L F; Zhao, M H

2010-01-01

314

Proposal for an advanced hybrid K-edge/XRF densitometry (HKED) using a monochromatic photon beam from laser Compton scattering  

NASA Astrophysics Data System (ADS)

The general purpose Monte Carlo electron-gamma shower computer code (EGS5) was used to obtain the U, Np, and Pu X-ray response from the hybrid K-edge/XRF densitometry (HKED). In the present simulation, we adopt a monochromatic, linearly polarized photon beam generated by using inverse Compton scattering of laser light with high-energy electrons from an energy recovery linac. The simulation has been carried out under various conditions of the U, Np, and Pu concentrations to investigate the effect of counting rates as well as counting precision. The results of the simulation show that the assessment time for low concentration Pu input solutions is reduced by improving the signal-to-background ratios. It is also shown that the Np concentration is determined with the counting precision of 0.67-1.8% in standard deviation during 1 h live time measurement for a 3N HNO 3 sample solution (1.1-1.3 g/cm 2) including U (10-200 g/L), Np (0.1 g/L), and Pu (10 g/L).

Shizuma, Toshiyuki; Hajima, Ryoichi; Hayakawa, Takehito; Fujiwara, Mamoru; Sonoda, Takashi; Seya, Michio

2011-10-01

315

A laser-Compton scattering prototype experiment at 100 MeV linac of Shanghai Institute of Applied Physics  

NASA Astrophysics Data System (ADS)

As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm and pulse width of 21 ns (full width at half maximum)] and electron bunches [with energy of 108 MeV and pulse width of 0.95 ns (rms)] at an angle of 42° between laser and electron beam. In order to measure the energy spectrum of LCS x-rays, a Si(Li) detector along the electron beam line axis is positioned at 9.8 m away from a LCS chamber. After background subtraction, the LCS x-ray spectrum with the peak energy of 29.1+/-4.4|stat+/-2.1|syst keV and the peak width (rms) of 7.8+/-2.8|stat+/-0.4|syst keV is observed. Normally the 100 MeV linac operates with the electron macropulse charge of 1.0 nC/pulse, and the electron and laser collision repetition rate of 20 Hz. Therefore, the total LCS x-ray flux of (5.2+/-2.0)×102 Hz can be achieved.

Luo, W.; Xu, W.; Pan, Q. Y.; Cai, X. Z.; Chen, J. G.; Chen, Y. Z.; Fan, G. T.; Fan, G. W.; Guo, W.; Li, Y. J.; Liu, W. H.; Lin, G. Q.; Ma, Y. G.; Shen, W. Q.; Shi, X. C.; Xu, B. J.; Xu, J. Q.; Xu, Y.; Zhang, H. O.; Yan, Z.; Yang, L. F.; Zhao, M. H.

2010-01-01

316

Constraint on pulsar wind properties from induced Compton scattering off radio pulses  

NASA Astrophysics Data System (ADS)

Pulsar winds have longstanding problems in energy conversion and pair cascade processes, which determine the magnetization ? , the pair multiplicity kappa , and the bulk Lorentz factor ? of the wind. We study induced Compton scattering by a relativistically moving cold plasma to constrain the wind properties by imposing that radio pulses from the pulsar itself are not scattered by the wind, as was first studied by Wilson and Rees [D. B. Wilson and M. J. Rees, Mon. Not. R. Astron. Soc., 185, 297 (1978)]. We find that relativistic effects cause a significant increase or decrease of the scattering coefficient depending on scattering geometry. Applying this to the Crab, we consider the uncertainties of the inclination angle of the wind velocity with respect to the radio beam ? _{pl} and the emission region size re, which determines the opening angle of the radio beam. We obtain the lower limit ? gtrsim 10^{1.7} r^{1/2}_{{e},3}? ^{-1}_pl(1+?)^{-1/4} (re = 10^3r_{{ e},3} cm) at the light cylinder r_{LC} for an inclined wind ? _{pl} >10^{-2.7}. For an aligned wind ? _{pl} < 10^{-2.7}, we require ? >10^{2.7} at r_{LC} and an additional constraint ? >10^{3.4}r^{1/5}_{{e},3}(1+?)^{-1/10} at the characteristic scattering radius r_c=10^{9.6}r^{2/5}_{{e},3} cm, within which the `lack of time' effect prevents scattering. Considering the lower limit kappa gtrsim 10^{6.6} suggested by recent studies of the Crab Nebula, for re=10^3 cm, we obtain the most optimistic constraint 10^{1.7}lesssim ? lesssim 10^{3.9} and 10^{6.6}lesssim kappa lesssim 10^{8.8}, which are independent of r when ? _{pl}˜ 1 and 1+? ˜ 1 at r_LC.

Tanaka, Shuta J.; Takahara, Fumio

2013-12-01

317

Constraint on Pulsar Wind Properties from Induced Compton Scattering off Radio Pulses  

NASA Astrophysics Data System (ADS)

Pulsar winds have longstanding problems in energy conversion and pair cascade processes which determine the magnetization ?, the pair multiplicity ? and the bulk Lorentz factor ? of the wind. We study induced Compton scattering by a relativistically moving cold plasma to constrain wind properties by imposing that radio pulses from the pulsar itself are not scattered by the wind as was first studied by Wilson & Rees. We find that relativistic effects cause a significant increase or decrease of the scattering coefficient depending on scattering geometry. Applying to the Crab, we consider uncertainties of an inclination angle of the wind velocity with respect to the radio beam ?_{pl} and the emission region size r_{e} which determines an opening angle of the radio beam. We obtain the lower limit ??10^{1.7}r^{1/2}_{e,3}?^{-1}_{pl}(1+?)^{-1/4} (r_{e}=10^3r_{e,3} cm) at the light cylinder r_{LC} for an inclined wind ?_{pl}>10^{-2.7}. For an aligned wind ?_{pl}<10^{-2.7}, we require ?>10^{2.7} at r_{LC} and an additional constraint ?>10^{3.4}r^{1/5}_{e,3}(1+?)^{-1/10} at the characteristic scattering radius r_{c}=10^{9.6}r^{2/5}_{e,3} cm within which the `lack of time' effect prevents scattering. Considering the lower limit ??10^{6.6} suggested by recent studies of the Crab Nebula, for r_{e}=10^3 cm, we obtain the most optimistic constraint 10^{1.7}???10^{3.9} and 10^{6.6}???10^{8.8} which are independent of r when ?_{pl}˜1 and 1+?˜1 at r_{LC}.

Tanaka, Shuta J.; Takahara, Fumio

2013-12-01

318

Deeply Virtual Compton Scattering and Meson Production at Jlab/CLAS  

SciTech Connect

This report reviews the recent experimental results from the CLAS collaboration (Hall B of Jefferson Lab, or JLab) on Deeply Virtual Compton Scattering (DVCS) and Deeply Virtual Meson Production (DVMP) and discusses their interpretation in the framework of Generalized Parton Distributions (GPDs). The impact of the experimental data on the applicability of the GPD mechanism to these exclusive reactions is discussed. Initial results obtained from JLab 6 GeV data indicate that DVCS might already be interpretable in this framework while GPD models fail to describe the exclusive meson production (DVMP) data with the GPD parameterizations presently used. An exception is the {phi} meson production for which the GPD mechanism appears to apply. The recent global analyses aiming to extract GPDs from fitting DVCS CLAS and world data are discussed. The GPD experimental program at CLAS12, planned with the upcoming 12 GeV upgrade of JLab, is briefly presented.

Hyon-Suk Jo

2012-04-01

319

X-ray phase-contrast imaging with an Inverse Compton Scattering source  

SciTech Connect

Single-shot in-line phase-contrast imaging with the Inverse Compton Scattering X-ray source available at ATF (Accelerator Test Facility) at Brookhaven National Laboratory is experimentally demonstrated. Phase-contrast images of polymer wires are obtained with a single X-ray pulse whose time length is about 1 picosecond. The edge-enhancement effect is clearly visible in the images and simulations show a quantitative agreement with experimental data. A phase-retrieval step in the image processing leads to a accurate estimation of the projected thickness of our samples. Finally, a single-shot image of a wasp is presented as an example of a biological sample.

Endrizzi, M. [Dip. di Fisica, Universita di Siena, Italy and Istituto Nazionale di Fisica Nucleare INFN, Sezione di Pisa (Italy); CSIRO, Materials Science and Engineering, Clayton South, 3169, VIC (Australia); Carpinelli, M.; Oliva, P.; Golosio, B. [Strutt. Dip. di Matematica e Fisica, Universita degli Studi di Sassari (Italy) and Istituto Nazionale di Fisica Nucleare INFN, Sezione di Cagliari (Italy); Delogu, P.; Stefanini, A. [Dip. di Fisica 'E. Fermi', Universita di Pisa, Italy and Istituto Nazionale di Fisica Nucleare INFN, Sezione di Pisa (Italy); Gureyev, T. E. [CSIRO, Materials Science and Engineering, Clayton South, 3169, VIC (Australia); Bottigli, U. [Dip. di Fisica, Universita di Siena, Italy and Istituto Nazionale di Fisica Nucleare INFN, Sezione di Pisa (Italy)

2010-07-23

320

Exploration of deeply virtual Compton scattering on the neutron in the Hall A of Jefferson Laboratory  

SciTech Connect

Generalized Parton Distributions (GPDs) are universal functions which provide a comprehensive description of hadron properties in terms of quarks and gluons. Deeply Virtual Compton Scattering (DVCS) is the simplest hard exclusive process involving GPDs. In particular, the DVCS on the neutron is mostly sensitive to E, the less constrained GPD, wich allows to access to the quark angular momentum. The first dedicated DVCS experiment on the neutron ran in the Hall A of Jefferson Lab in fall 2004. The high luminosity of the experiment and the resulting background rate recquired specific devices which are decribed in this document. The analysis methods and the experiment results, leading to preliminary constraints on the GPD E, are presented.

Malek Mazouz

2006-12-08

321

Measurement of deeply virtual compton scattering with a polarized-proton target.  

PubMed

The longitudinal target-spin asymmetry AUL for the exclusive electroproduction of high-energy photons was measured for the first time in ep-->e;'pgamma. The data have been accumulated at JLab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH3 target. A significant azimuthal angular dependence was observed, resulting from the interference of the deeply virtual Compton scattering and Bethe-Heitler processes. The amplitude of the sinvarphi moment is 0.252+/-0.042stat+/-0.020sys. Theoretical calculations are in good agreement with the magnitude and the kinematic dependence of the target-spin asymmetry, which is sensitive to the generalized parton distributions H and H. PMID:17026221

Chen, S; Avakian, H; Burkert, V D; Eugenio, P; Adams, G; Amarian, M; Ambrozewicz, P; Anghinolfi, M; Asryan, G; Bagdasaryan, H; Baillie, N; Ball, J P; Baltzell, N A; Barrow, S; Batourine, V; Battaglieri, M; Beard, K; Bedlinskiy, I; Bektasoglu, M; Bellis, M; Benmouna, N; Berman, B L; Biselli, A S; Bonner, B E; Bouchigny, S; Boiarinov, S; Bosted, P; Bradford, R; Branford, D; Briscoe, W J; Brooks, W K; Bültmann, S; Butuceanu, C; Calarco, J R; Careccia, S L; Carman, D S; Carnahan, B; Cazes, A; Cole, P L; Collins, P; Coltharp, P; Cords, D; Corvisiero, P; Crabb, D; Crannell, H; Crede, V; Cummings, J P; DeMasi, R; DeVita, R; De Sanctis, E; Degtyarenko, P V; Denizli, H; Dennis, L; Deur, A; Dharmawardane, K V; Dhuga, K S; Djalali, C; Dodge, G E; Donnelly, J; Doughty, D; Dugger, M; Dytman, S; Dzyubak, O P; Egiyan, H; Egiyan, K S; El Fassi, L; Elouadrhiri, L; Fatemi, R; Fedotov, G; Feldman, G; Feuerbach, R J; Forest, T A; Funsten, H; Garçon, M; Gavalian, G; Gilfoyle, G P; Giovanetti, K L; Girod, F X; Goetz, J T; Golovatch, E; Gonenc, A; Gothe, R W; Griffioen, K A; Guidal, M; Guillo, M; Guler, N; Guo, L; Gyurjyan, V; Hadjidakis, C; Hafidi, K; Hakobyan, H; Hakobyan, R S; Hardie, J; Heddle, D; Hersman, F W; Hicks, K; Hleiqawi, I; Holtrop, M; Huertas, M; Hyde-Wright, C E; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Ito, M M; Jenkins, D; Jo, H S; Joo, K; Juengst, H G; Keith, C; Kellie, J D; Khandaker, M; Kim, K Y; Kim, K; Kim, W; Klein, A; Klein, F J; Klusman, M; Kossov, M; Kramer, L H; Kubarovsky, V; Kuhn, J; Kuhn, S E; Kuleshov, S V; Lachniet, J; Laget, J M; Langheinrich, J; Lawrence, D; Li, Ji; Lima, A C S; Livingston, K; Lu, H; Lukashin, K; MacCormick, M; Markov, N; McAleer, S; McKinnon, B; McNabb, J W C; Mecking, B A; Mestayer, M D; Meyer, C A; Mibe, T; Mikhailov, K; Minehart, R; Mirazita, M; Miskimen, R; Mokeev, V; Morand, L; Morrow, S A; Moteabbed, M; Mueller, J; Mutchler, G S; Nadel-Turonski, P; Napolitano, J; Nasseripour, R; Natasha, N; Niccolai, S; Niculescu, G; Niculescu, I; Niczyporuk, B B; Niroula, M R; Niyazov, R A; Nozar, M; O'Rielly, G V; Osipenko, M; Ostrovidov, A I; Park, K; Pasyuk, E; Paterson, C; Philips, S A; Pierce, J; Pivnyuk, N; Pocanic, D; Pogorelko, O; Polli, E; Popa, I; Pozdniakov, S; Preedom, B M; Price, J W; Prok, Y; Protopopescu, D; Qin, L M; Raue, B A; Riccardi, G; Ricco, G; Ripani, M; Ritchie, B G; Ronchetti, F; Rosner, G; Rossi, P; Rowntree, D; Rubin, P D; Sabatié, F; Salgado, C; Santoro, J P; Sapunenko, V; Schumacher, R A; Serov, V S; Sharabian, Y G; Shaw, J; Shvedunov, N V; Skabelin, A V; Smith, E S; Smith, L C; Sober, D I; Stavinsky, A; Stepanyan, S S; Stepanyan, S; Stokes, B E; Stoler, P; Strakovsky, I I; Strauch, S; Suleiman, R; Taiuti, M; Tedeschi, D J; Thoma, U; Tkabladze, A; Tkachenko, S; Todor, L; Tur, C; Ungaro, M; Vanderhaeghen, M; Vineyard, M F; Vlassov, A V; Watts, D P; Weinstein, L B; Weygand, D P; Williams, M; Wolin, E; Wood, M H; Yegneswaran, A; Yun, J; Zana, L; Zhang, J; Zhao, B; Zhao, Z

2006-08-18

322

Scaling tests of the cross section for deeply virtual Compton scattering.  

PubMed

We present the first measurements of the e[over -->]p-->epgamma cross section in the deeply virtual Compton scattering (DVCS) regime and the valence quark region. The Q(2) dependence (from 1.5 to 2.3 GeV(2)) of the helicity-dependent cross section indicates the twist-2 dominance of DVCS, proving that generalized parton distributions (GPDs) are accessible to experiment at moderate Q(2). The helicity-independent cross section is also measured at Q(2)=2.3 GeV(2). We present the first model-independent measurement of linear combinations of GPDs and GPD integrals up to the twist-3 approximation. PMID:17280421

Camacho, C Muñoz; Camsonne, A; Mazouz, M; Ferdi, C; Gavalian, G; Kuchina, E; Amarian, M; Aniol, K A; Beaumel, M; Benaoum, H; Bertin, P; Brossard, M; Chen, J-P; Chudakov, E; Craver, B; Cusanno, F; de Jager, C W; Deur, A; Feuerbach, R; Fieschi, J-M; Frullani, S; Garçon, M; Garibaldi, F; Gayou, O; Gilman, R; Gomez, J; Gueye, P; Guichon, P A M; Guillon, B; Hansen, O; Hayes, D; Higinbotham, D; Holmstrom, T; Hyde-Wright, C E; Ibrahim, H; Igarashi, R; Jiang, X; Jo, H S; Kaufman, L J; Kelleher, A; Kolarkar, A; Kumbartzki, G; Laveissière, G; Lerose, J J; Lindgren, R; Liyanage, N; Lu, H-J; Margaziotis, D J; Meziani, Z-E; McCormick, K; Michaels, R; Michel, B; Moffit, B; Monaghan, P; Nanda, S; Nelyubin, V; Potokar, M; Qiang, Y; Ransome, R D; Réal, J-S; Reitz, B; Roblin, Y; Roche, J; Sabatié, F; Saha, A; Sirca, S; Slifer, K; Solvignon, P; Subedi, R; Sulkosky, V; Ulmer, P E; Voutier, E; Wang, K; Weinstein, L B; Wojtsekhowski, B; Zheng, X; Zhu, L

2006-12-31

323

Deeply virtual Compton scattering at small x and the access to the GPD H  

NASA Astrophysics Data System (ADS)

We give a partonic interpretation for the deeply virtual Compton scattering (DVCS) measurements of the H1 and ZEUS Collaborations in the small- x region in terms of generalized parton distributions. Thereby we have a closer look at the skewness effect, parameterization of the t-dependence, revealing the chromomagnetic pomeron, and at a model-dependent access to the anomalous gravitomagnetic moment of nucleon. We also quantify the reparameterization of generalized parton distributions resulting from the inclusion of radiative corrections up to next-to-next-to-leading order. Beyond the leading order approximation, our findings are compatible with a 'holographic' principle that would arise from a (broken) SO(2,1) symmetry. Utilizing our leading-order findings, we also perform a first model-dependent "dispersion relation" fit of HERMES and JLAB DVCS measurements. From that we extract the generalized parton distribution H on its cross-over line and predict the beam charge-spin asymmetry, measurable at COMPASS.

Kumeri?ki, Krešimir; Müller, Dieter

2010-12-01

324

Quasi-monochromatic hard X-ray source via laser Compton scattering and its application  

NASA Astrophysics Data System (ADS)

We have developed a quasi-monochromatic hard X-ray source via laser Compton scattering (LCS) based on an S-band compact electron linac at AIST. The number of total photons and the maximum X-ray energy was 107 photons/sec and about 40 keV, respectively, in 15-degree crossing angle between a 42 MeV electron beam and a 800 nm Ti:Sa laser. The biological observation of the human bone with fractures has been successfully demonstrated using the LCS X-ray of 26.4 keV with the in-line phase contrast scheme. Good contrast enhancement is clearly observed between the absorption and the phase contrast images.

Kuroda, R.; Toyokawa, H.; Yasumoto, M.; Ikeura-Sekiguchi, H.; Koike, M.; Yamada, K.; Yanagida, T.; Nakajyo, T.; Sakai, F.; Mori, K.

2011-05-01

325

Detection of radioactive isotopes by using laser Compton scattered ?-ray beams  

NASA Astrophysics Data System (ADS)

Non-destructive detection and assay of nuclear materials is one of the most critical issues for both the management of nuclear waste and the non-proliferation of nuclear materials. We use laser Compton scattered (LCS) ?-ray beams and the nuclear resonance fluorescence (NRF) for the non-destructive detection of radioactive materials. Quasi-monochromatic and energy-tunable LCS ?-ray beams help improve the signal-to-noise ratio during NRF measurements. We developed the conceptual design of a high-flux ?-ray source with an energy-recovery linac, which produces a ?-ray beam at the flux of 1013 photons/s. In this paper, we discuss the execution of simulation studies using a Monte Carlo code, results of a proof-of-principle experiment for isotope detection, and the status of the development of LCS X-ray and ?-ray facilities.

Hajima, R.; Kikuzawa, N.; Nishimori, N.; Hayakawa, T.; Shizuma, T.; Kawase, K.; Kando, M.; Minehara, E.; Toyokawa, H.; Ohgaki, H.

2009-09-01

326

Differential cross sections of proton compton scattering at photon laboratory energies between 700 and 1000 MeV  

Microsoft Academic Search

Differential cross sections of proton Compton scattering have been measured at the Bonn 2.5 GeV synchrotron. 78 data points are presented as angular distributions at photon lab energies of 700, 750, 800, 850, 900, and 950MeV. The c.m. scattering angle ranges from 40°–130°, corresponding to a variation of the four momentum transfer squared betweent=-0.10 tot=-0.96 GeV2 at 700 and 950

M. Jung; J. Kattein; H. Kück; P. Leu; K.-D. de Marné; R. Wedemeyer; N. Wermes

1981-01-01

327

Risk management approach for de-orbiting of the Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

De-orbiting of space debris into Earth is one of the methods to control and minimize the degradation of the space environment. The de-orbiting scenario poses a challenge of providing safety for the Earth population and other space-based assets below the orbit track of the spacecraft being de-orbited. Rigorous risk management is needed to provide the necessary safety margin for de-orbit operations. These challenges were faced during the controlled de-orbit of the Compton Gamma Ray Observatory (CGRO) into the Pacific Ocean on June 4, 2000. This paper presents a risk management approach utilized at various stages of this mission; processes used to identify credible contingencies; and planned responses to contingencies for use during mission execution.

Ahmed, Mansoor; Mangus, David; Burch, Preston

2001-10-01

328

Gamma ray monitoring of a AGN and galactic black hole candidates by the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

The Compton Gamma-Ray Observatory's Burst and Transient Source Experiment (BATSE) has a powerful capability to provide nearly uninterrupted monitoring in the 25 keV-10 MeV range of both active galactic nuclei (AGN) and galactic black hole candidates (GBHC) such as Cygnus X-1, using the occultation of cosmic sources by the Earth. Since the Crab is detected by the BATSE Large Area Detectors with roughly 25(sigma) significance in the 15-125 keV range in a single rise or set, a variation by a factor of two of a source having one-tenth the strength of Cygnus X-1 should be detectable within a day. Methods of modeling the background are discussed which will increase the accuracy, sensitivity, and reliability of the results beyond those obtainable from a linear background fit with a single rise or set discontinuity.

Skelton, R. T.; Ling, James C.; Wheaton, William A.; Harmon, Alan; Fishman, G. J.; Meegan, C. A.; Paciesas, William S.; Gruber, Duane E.; Rubin, Brad; Wilson, R. B.

1992-01-01

329

Thermal Comptonization models for gamma-ray emission from black-hole sources  

SciTech Connect

Black holes power the variable luminous emission observed from quasars and the nuclei of active galaxies; at least we assume so here. The list of black-hole candidates detected at gamma-ray energies includes the galactic binary X-ray source Cygnus X-1, the Galactic Center, and the extragalactic sources Cen A (NGC 5128), NGC 4151, MCG 8-11-11 and 3C 273. The luminosity of these objects peaks in the photon energy range 0.1/approx lt/epsilon/approx lt/10 MeV and dominates the total energy output in the observable wavebands. SAS-2 and COS-B upper limits and observations indicate a cutoff or softening in their spectra between /approximately/1 and /approximately/30 MeV, which is probably due to absorption of gamma rays by photon-photon pair production or a break in the underlying particle spectrum. Indeed, spectral softening at MeV energies seems to be required of active galactic nuclei (AGN) in general; otherwise the superposition of the emission from these sources would conflict with observations of the diffuse gamma-ray background radiation. The salient features associated with gamma-ray emission from the above-mentioned sources are summarized in this paper, beginning with Cygnus X-1, the best-studied black-hole candidate. Because of similarity in properties, models developed to explain the X-ray and gamma-ray observations of Cygnus X-1 can be equally applied to AGN. In this review, successes and limitations of thermal Comptonization models for the high-energy emission of black-hole sources are considered. 60 refs., 1 fig., 2 tabs.

Dermer, C.D.

1989-03-16

330

Mobile, hybrid Compton/coded aperture imaging for detection, identification and localization of gamma-ray sources at stand-off distances  

NASA Astrophysics Data System (ADS)

The Stand-off Radiation Detection System (SORDS) program is an Advanced Technology Demonstration (ATD) project through the Department of Homeland Security's Domestic Nuclear Detection Office (DNDO) with the goal of detection, identification and localization of weak radiological sources in the presence of large dynamic backgrounds. The Raytheon-SORDS Tri-Modal Imager (TMI) is a mobile truck-based, hybrid gamma-ray imaging system able to quickly detect, identify and localize, radiation sources at standoff distances through improved sensitivity while minimizing the false alarm rate. Reconstruction of gamma-ray sources is performed using a combination of two imaging modalities; coded aperture and Compton scatter imaging. The TMI consists of 35 sodium iodide (NaI) crystals 5x5x2 in3 each, arranged in a random coded aperture mask array (CA), followed by 30 position sensitive NaI bars each 24x2.5x3 in3 called the detection array (DA). The CA array acts as both a coded aperture mask and scattering detector for Compton events. The large-area DA array acts as a collection detector for both Compton scattered events and coded aperture events. In this thesis, developed coded aperture, Compton and hybrid imaging algorithms will be described along with their performance. It will be shown that multiple imaging modalities can be fused to improve detection sensitivity over a broader energy range than either alone. Since the TMI is a moving system, peripheral data, such as a Global Positioning System (GPS) and Inertial Navigation System (INS) must also be incorporated. A method of adapting static imaging algorithms to a moving platform has been developed. Also, algorithms were developed in parallel with detector hardware, through the use of extensive simulations performed with the Geometry and Tracking Toolkit v4 (GEANT4). Simulations have been well validated against measured data. Results of image reconstruction algorithms at various speeds and distances will be presented as well as localization capability. Utilizing imaging information will show signal-to-noise gains over spectroscopic algorithms alone.

Tornga, Shawn R.

331

500 MW X-Band RF System of a 0.25 GeV Electron LINAC for Advanced Compton Scattering Source Application  

SciTech Connect

A Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering light source is being developed at LLNL in collaboration with the SLAC National Accelerator Laboratory. The electron beam for the Compton scattering interaction will be generated by a X-band RF gun and a X-band LINAC at the frequency of 11.424 GHz. High power RF in excess of 500 MW is needed to accelerate the electrons to energy of 250 MeV or greater for the interaction. Two high power klystron amplifiers, each capable of generating 50 MW, 1.5 msec pulses, will be the main high power RF sources for the system. These klystrons will be powered by state of the art solid-state high voltage modulators. A RF pulse compressor, similar to the SLED II pulse compressor, will compress the klystron output pulse with a power gain factor of five. For compactness consideration, we are looking at a folded waveguide setup. This will give us 500 MW at output of the compressor. The compressed pulse will then be distributed to the RF gun and to six traveling wave accelerator sections. Phase and amplitude control are located at the RF gun input and additional control points along the LINAC to allow for parameter control during operation. This high power RF system is being designed and constructed. In this paper, we will present the design, layout, and status of this RF system.

Chu, Tak Sum; /LLNL, Livermore; Anderson, Scott; /LLNL, Livermore; Barty, Christopher; /LLNL, Livermore; Gibson, David; /LLNL, Livermore; Hartemann, Fred; /LLNL, Livermore; Marsh, Roark; /LLNL, Livermore; Siders, Craig; /LLNL, Livermore; Adolphsen, Chris; /SLAC; Jongewaard, Erik; /SLAC; Raubenheimer, Tor; /SLAC; Tantawi, Sami; /SLAC; Vlieks, Arnold; /SLAC; Wang, Juwen; /SLAC

2012-07-03

332

500 MW X-BAND RF SYSTEM OF A 0.25 GEV ELECTRON LINAC FOR ADVANCED COMPTON SCATTERING SOURCE APPLICATION  

SciTech Connect

A Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering light source is being developed at LLNL in collaboration with SLAC National Accelerator Laboratory. The electron beam for the Compton scattering interaction will be generated by a X-band RF gun and a X-band LINAC at the frequency of 11.424 GHz. High power RF in excess of 500 MW is needed to accelerate the electrons to energy of 250 MeV or greater for the interaction. Two high power klystron amplifiers, each capable of generating 50 MW, 1.5 msec pulses, will be the main high power RF sources for the system. These klystrons will be powered by state of the art solid-state high voltage modulators. A RF pulse compressor, similar to the SLED II pulse compressor, will compress the klystron output pulse with a power gain factor of five. For compactness consideration, we are looking at a folded waveguide setup. This will give us 500 MW at output of the compressor. The compressed pulse will then be distributed to the RF gun and to six traveling wave accelerator sections. Phase and amplitude control are located at the RF gun input and additional control points along the LINAC to allow for parameter control during operation. This high power RF system is being designed and constructed. In this paper, we will present the design, layout, and status of this RF system.

Chu, T S; Anderson, S G; Gibson, D J; Hartemann, F V; Marsh, R A; Siders, C; Barty, C P; Adolphsen, C; Jongewaard, E; Tantawi, S; Vlieks, A; Wang, J W; Raubenheimer, T

2010-05-12

333

A new data treatment scheme for integrated intensities in neutron Compton scattering  

NASA Astrophysics Data System (ADS)

A new data reduction scheme is presented for time-of-flight data collected in neutron Compton scattering experiments with the aim of obtaining the scattering intensities. The method proposed is a single number approach as it makes use of the count rates detected in the individual time-of-flight channels. The most convenient seems to be the variant of the method where time-of-flight channels are chosen corresponding to centers of recoil peaks of individual masses. With such a choice of time-of-flight channels, the method presented is more robust against unwanted background signals and noise than the method widely used in NCS studies based on fitting entire time-of-flight band shapes in the framework of the convolution approximation. Moreover, it should perform better than the model-free Dorner method as it does not require the numerical integration of the signal, which is also sensitive to baseline and noise. As an example of the performance of the new method, polyethylene data are treated and compared to results obtained previously using conventional data reduction and the model-free method proposed by Dorner. It is shown that all three data reduction schemes lead to the same results for the scattering intensities of protons in polyethylene, thus strengthening the conclusion about the anomalous scattering cross-section of protons in this substance. In the future the new data reduction scheme can be used to treat the data from other experiments where the conventional NCS data treatment and/or Dorner method fail due to noise and/or unwanted background signals present in the time-of-flight spectra.

Krzystyniak, M.; Chatzidimitriou-Dreismann, C. A.

2008-03-01

334

The Hard Components of Scattered Gamma-Rays  

Microsoft Academic Search

A summary is given of theoretical information on the three processes by which gamma-rays can be elastically scattered by atoms, viz. Rayleigh scattering by bound electrons, Thomson scattering by the nuclear charge and (exceptionally) nuclear resonant scattering.Interference between the three scattered waves is considered and shown to be of practical importance as between Rayleigh and Thomson scattering of hard gamma-rays

P B Moon

1950-01-01

335

Harmonic radiation of a relativistic nonlinear inverse Compton scattering using two laser wavelengths  

NASA Astrophysics Data System (ADS)

The use of two different wavelength lasers in the nonlinear regime of the inverse Compton scattering interaction is proposed in order to provide a new strategy for controlling scattered photon energy distributions in the x-ray to ?-ray spectral region. In this nonlinear interaction, the component of the relativistic electron’s trajectory driven by a longer-wavelength laser with the normalized vector potential aL˜1 is a large oscillatory figure-8; in the proposed scenario a rapid small-amplitude oscillation induced by a shorter-wavelength laser is superimposed upon this figure-8. Thus, the electron’s momentum is mainly supplied from longer-wavelength laser, while the high-frequency part of the acceleration is given by shorter-wavelength laser. In this way, the harmonics radiated at high frequency from the oscillating electron can be strongly modified by the nonlinear motion initiated by the low frequency, large aL laser resulting in the generation of the harmonics with the photon energy of 4?2h?(?L,short+n?L,long). In this paper, the electron’s kinetics in the two-wavelength laser field and the concomitant emitted radiation spectrum are examined, with numerical illustrations based on a classical Lienard-Wiechert potential formalism provided.

Sakai, Y.; Williams, O.; Andonian, G.; Fukasawa, A.; Hemsing, E.; Marinelli, A.; Barber, S.; O'Shea, F. H.; Rosenzweig, J. B.

2011-12-01

336

X-ray polarization signatures of Compton scattering in magnetic cataclysmic variables  

NASA Astrophysics Data System (ADS)

Compton scattering within the accretion column of magnetic cataclysmic variables (mCVs) can induce a net polarization in the X-ray emission. We investigate this process using Monte Carlo simulations and find that significant polarization can arise as a result of the stratified flow structure in the shock-ionized column. We find that the degree of linear polarization can reach levels up to ~8 per cent for systems with high accretion rates and low white dwarf masses, when viewed at large inclination angles with respect to the accretion column axis. These levels are substantially higher than previously predicted estimates using an accretion column model with uniform density and temperature. We also find that for systems with a relatively low-mass white dwarf accreting at a high accretion rate, the polarization properties may be insensitive to the magnetic field, since most of the scattering occurs at the base of the accretion column where the density structure is determined mainly by bremsstrahlung cooling instead of cyclotron cooling.

McNamara, A. L.; Kuncic, Z.; Wu, K.

2008-06-01

337

Applications and Imaging Techniques of a Si/CdTe Compton Gamma-Ray Camera  

NASA Astrophysics Data System (ADS)

By using a new Compton camera consisting of a silicon double-sided strip detector (Si-DSD) and a CdTe doublesided strip detector (CdTe-DSD), originally developed for the ASTRO-H satellite mission, an experiment involving imaging radioisotopes was conducted to study their feasibility for hotspot monitoring. In addition to the hotspot imaging already provided by commercial imaging systems, identification of various radioisotopes is possible thanks to the good energy resolution obtained by the semiconductor detectors. Three radioisotopes of 133Ba (356 keV), 22Na (511 keV) and 137Cs (662 keV) were individually imaged by applying event selection in the energy window and the gamma-ray images were correctly overlapped by an optical picture. Detection efficiency of 1.68 ×10-4 (effective area: 1.7×10-3 cm2) and angular resolution of 3.8 degrees were obtained by stacking five detector modules for a 662 keV gamma ray. The higher detection efficiency required in specific use can be achieved by stacking more detector modules.

Takeda, Shin'ichiro; Ichinohe, Yuto; Hagino, Kouichi; Odaka, Hirokazu; Yuasa, Takayuki; Ishikawa, Shin-nosuke; Fukuyama, Taro; Saito, Shinya; Sato, Tamotsu; Sato, Goro; Watanabe, Shin; Kokubun, Motohide; Takahashi, Tadayuki; Yamaguchi, Mitsutaka; Tajima, Hiroyasu; Tanaka, Takaaki; Nakazawa, Kazuhiro; Fukazawa, Yasushi; Nakano, Takashi

338

Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Pioneer Venus Orbiter, Compton Gamma-Ray Observatory, and ULYSSES  

NASA Astrophysics Data System (ADS)

Between the Compton Gamma Ray Observatory (CGRO) launch in 1991 April and the Pioneer Venus Orbiter (PVO) demise in 1992 October, concurrent coverage by CGRO, PVO, and Ulysses was obtained for several hundred gamma-ray bursts (GRBs). Although most of these were below the PVO and Ulysses thresholds, 37 were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to ~2° accuracy by the CGRO Burst and Transient Source Experiment (BATSE), and three were also localized by COMPTEL. We computed arrival-time error boxes, whose larger dimensions range from about 2' to several degrees and whose smaller dimensions are in the arcminute range. Twelve have areas less than 10 arcmin2, and only four have areas greater than 1 deg2. The area of the smallest box is 0.44 arcmin2. We find that the overall BATSE localization accuracy for these events is consistent with the most recent stated uncertainties. This work indicates that the ROSAT soft X-ray source found within a preliminary IPN error box for GB920501 (Trig 1576) (Hurley et al.) is less likely to be the GRB counterpart than previously reported.

Laros, J. G.; Hurley, K. C.; Fenimore, E. E.; Klebesadel, R. W.; Briggs, M. S.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.; Cline, T. L.; Boer, M.; Niel, M.

1998-10-01

339

Analytical inversion of the Compton transform using the full set of available projections  

NASA Astrophysics Data System (ADS)

The detection of gamma rays using a camera based on Compton scattering has become widespread because of its sensitivity and efficiency. Apart from the challenge arising from the Compton camera design, another price must be paid: the complex image reconstruction process of the object under study from the measured Compton scattered data. In this paper, a mathematical model of projections generated by photons scattered in a generic Compton camera is defined, relating the projections to the object by an integral transform, namely the Compton transform. The set of projections can be split into subsets following the slope ? of the direction of the scattered photons. We show that each subset allows us to invert the Compton transform and exactly recover the image of the object. In practical applications, where the number of acquired photons is low and each reconstructed image is noisy, averaging improves dramatically the signal-to-noise ratio. Finally, the validity of the approach is proved by numerical experiments.

Maxim, Voichi?a; Frande?, Mirela; Prost, Rémy

2009-09-01

340

Development of Electron tracking Compton Camera based on micro pixel gas detector and its application for medical imaging  

Microsoft Academic Search

We have developed the Electron tracking Compton Camera (ETCC) with reconstructing the 3-D tracks of the scattered electron in Compton process for both gamma-ray astronomy and medical imaging [1–3]. By measuring both the directions and energies of a recoil gamma ray and a scattered electron, the direction of the incident gamma ray is determined for an individual photon. Furthermore, a

F. T. Tanimori; H. Amano; K. Hattori; C. Ida; S. Iwaki; S. Kabuki; H. Kawashima; H. Kimura; R. Kohara; A. Kubo; H. Kubo; E. Kunieda; S. Kurosawa; K. Miuchi; O. Miyazaki; T. Nakazawa; T. Nakahara; Y. Nakamoto; H. Nishimura; K. Ogawa; T. Okada; Y. Okada; T. Shirahata; H. Saji; A. Takada; K. Tsuchiya; M. Ueda; K. Ueno; E. Yamamoto

2008-01-01

341

Hadron Optics in Three-Dimensional Invariant Coordinate Space from Deeply VirtualCompton Scattering  

SciTech Connect

The Fourier transform of the deeply virtual Compton scattering amplitude (DVCS) with respect to the skewness parameter {zeta} = Q{sup 2}/2p {center_dot} q can be used to provide an image of the target hadron in the boost-invariant variable {sigma}, the coordinate conjugate to light-front time {tau} = t + z/c. As an illustration, we construct a consistent covariant model of the DVCS amplitude and its associated generalized parton distributions using the quantum fluctuations of a fermion state at one loop in QED, thus providing a representation of the light-front wave functions of a lepton in {sigma} space. A consistent model for hadronic amplitudes can then be obtained by differentiating the light-front wave functions with respect to the bound-state mass. The resulting DVCS helicity amplitudes are evaluated as a function of {sigma} and the impact parameter {rvec b}{sub {perpendicular}}, thus providing a light-front image of the target hadron in a frame-independent three-dimensional light-front coordinate space. Models for the LFWFs of hadrons in (3 + 1) dimensions displaying confinement at large distances and conformal symmetry at short distances have been obtained using the AdS/CFT method. We also compute the LFWFs in this model in invariant three dimensional coordinate space. We find that in the models studied, the Fourier transform of the DVCS amplitudes exhibit diffraction patterns. The results are analogous to the diffractive scattering of a wave in optics where the distribution in ? measures the physical size of the scattering center in a one-dimensional system.

Brodsky, S.J.; Chakrabarti, D.; Harindranath, A.; Mukherjee, A.; Vary, J.P.

2006-11-30

342

Measurement of effective atomic number of gunshot residues using scattering of gamma rays  

NASA Astrophysics Data System (ADS)

Better understanding of gunshot residues and the major elemental composition would be valuable to forensic scientists for their analysis work and interpretation of results. In the present work, the effective atomic numbers of gunshot residues (cartridge case, bullet core, bullet jacket and gunpowder) were analyzed using energy dispersive X-ray analysis (EDX). The scattering of 59.54 keV gamma rays is studied using a high-resolution HPGe detector. The experiment is performed on various elements with atomic number in the 4?Z?82. The intensity ratio of coherent to Compton scattered peaks, corrected for photo-peak efficiency of gamma detector and absorption of photons in the sample and air, is plotted as a function of atomic number and constituted a best-fit-curve. From this fit-curve, the respective effective atomic numbers of gunshot residues are determined.

Y?lmaz, Demet; Tur?ucu, Ahmet; Uzuno?lu, Zeynep; Korucu, Demet

2014-09-01

343

Virtual Compton Scattering and the Generalized Polarizabilities of the Proton at Q^2=0.92 and 1.76 GeV^2  

SciTech Connect

Virtual Compton Scattering (VCS) on the proton has been studied at Jefferson Lab using the exclusive photon electroproduction reaction (e p --> e p gamma). This paper gives a detailed account of the analysis which has led to the determination of the structure functions P{sub LL}-P{sub TT}/epsilon and P{sub LT}, and the electric and magnetic generalized polarizabilities (GPs) alpha{sub E}(Q{sup 2}) and beta{sub M}(Q{sup 2}) at values of the four-momentum transfer squared Q{sup 2} = 0.92 and 1.76 GeV{sup 2}. These data, together with the results of VCS experiments at lower momenta, help building a coherent picture of the electric and magnetic GPs of the proton over the full measured Q{sup 2}-range, and point to their non-trivial behavior.

Helene Fonvieille, Geraud Laveissiere, Natalie Degrande, Stephanie Jaminion, Christophe Jutier, Luminita Todor, L. Van Hoorebeke, Bryon Anderson, Konrad Aniol, Kathleen Arundell, Gerard Audit, Leonard Auerbach, F. Baker, Maud Baylac, J. Berthot, Pierre Bertin, William Bertozzi, Louis Bimbot, Werner Boeglin, Edward Brash, Vincent Breton, Herbert Breuer, Etienne Burtin, John Calarco, Lawrence Cardman, Christian Cavata, Jian-Ping Chen, Eugene Chudakov, Evaristo Cisbani, Daniel Dale, Cornelis De Jager, Raffaele De Leo, Alexandre Deur, Nicole D'Hose, Gail Dodge, John Domingo, Latifa Elouadrhiri, Martin Epstein, Lars Ewell, John Finn, Kevin Fissum, Guy Fournier, Bernhard Frois, Salvatore Frullani, Christophe Furget, Haiyan Gao, Juncai Gao, Franco Garibaldi, Ashot Gasparian, Shalev Gilad, Ronald Gilman, Oleksandr Glamazdin, Charles Glashausser, Javier Gomez, Viktor Gorbenko, Pierre Guichon, Jens-Ole Hansen, Richard Holmes, Maurik Holtrop, Calvin Howell, Garth Huber, Charles Hyde, Sebastien Incerti, Mauro Iodice, Johann Jardillier, Mark Jones, Seigo Kato, James Kelly, Armen Ketikyan, Mohammad Khayat, Kouichi Kino, Serge Kox, Laird Kramer, Krishna Kumar, Gerfried Kumbartzki, Michael Kuss, Antonio Leone, John LeRose, Richard Lindgren, Nilanga Liyanage, George Lolos, Kazushige Maeda, Sergey Malov, D. Manley, Claude Marchand, Dominique Marchand, Demetrius Margaziotis, Pete Markowitz, Jacques Marroncle, Jacques Martino, Kathy McCormick, James McIntyre, Surik Mehrabyan, Fernand Merchez, Zein-Eddine Meziani, Robert Michaels, Jean Mougey, Sirish Nanda, Amra Offermann, Zisis Papandreou, Charles Perdrisat, R. Perrino, Gerassimos Petratos, Stephane Platchkov, Roman Pomatsalyuk, David Prout, Vina Punjabi, Thierry Pussieux, Gilles Quemener, Ronald Ransome, Oliver Ravel, Jean-Sebastien Real, Yves Roblin, David Rowntree, Gary Rutledge, Paul Rutt, Arunava Saha, Teijiro Saito, Adam Sarty, Tim Smith, Paul Souder, Riad Suleiman, Jeffrey Templon, Tatsuo Terasawa, Raphael Tieulent, Egle Tomasi, Hiroaki Tsubota, Hiroaki Ueno, Paul Ulmer, Guido Urciuoli, Marc Vanderhaeghen, Rob van der Meer, R.Van De Vyver, Pascal Vernin, Branislav Vlahovic, Hakob Voskanyan, Eric Voutier, John Watson, Lawrence Weinstein, Krishni Wijesooriya, Richard Wilson, Bogdan Wojtsekhowski, Dan Zainea, Zilu Zhou, Rachele Di Salvo

2012-07-01

344

Beam Measurement of 11.424 GHz X-Band Linac for Compton Scattering X-ray Source  

Microsoft Academic Search

An inverse Compton scattering X-ray source for medical applications, consisting of an X-band (11.424 GHz) linac and Q-switched Nd:YAG laser, is currently being developed at the University of Tokyo. This system uses an X-band 3.5-cell thermionic cathode RF gun for electron beam generation. We can obtain a multi-bunch electron beam with this gun. The beam is accelerated to 30 MeV

Takuya Natsui; Azusa Mori; Hirotoshi Masuda; Mitsuru Uesaka; Fumito Sakamoto

2010-01-01

345

Use of dispersion relations in hard exclusive processes and the partonic interpretation of deeply virtual Compton scattering  

NASA Astrophysics Data System (ADS)

Recently dispersion relations have been applied to hard exclusive processes such as deeply virtual Compton scattering, and a holographic principle was proposed that maps out the generalized parton distributions entering the soft matrix elements for the processes from their values on a given kinematical ridge. We examine possible pitfalls associated with the implicit, direct identification in this approach of the physical hadronic states with colored partons, and suggest an improved treatment of this assumption.

Goldstein, Gary R.; Liuti, Simonetta

2009-10-01

346

Evidence for positive polarity of the spin moment in hcp Sm determined from a magnetic Compton-scattering experiment  

SciTech Connect

The magnetic moment of Sm{sup 3+} in hcp Sm was studied with a magnetic Compton-scattering experiment with the aid of a pulse magnet. We have successfully obtained direct evidence for a positive contribution of the spin moment to the total moment, opposite to the case for a free ion. The enhancement of the spin moment by incorporation of the conduction electron polarization is observed. {copyright} {ital 1997} {ital The American Physical Society}

Adachi, H.; Ino, H. [Department of Materials Science, The University of Tokyo, Bunkyo, Tokyo 113 (Japan)] [Department of Materials Science, The University of Tokyo, Bunkyo, Tokyo 113 (Japan); Koizumi, A.; Sakai, N. [Faculty of Science, Himeji Institute of Technology, Ako-gun, Hyogo 678-12 (Japan)] [Faculty of Science, Himeji Institute of Technology, Ako-gun, Hyogo 678-12 (Japan); Tanaka, Y. [The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01 (Japan)] [The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-01 (Japan); Kawata, H. [Photon Factory, National Laboratory for High Energy Physics, Tsukuba, Ibaraki 305 (Japan)] [Photon Factory, National Laboratory for High Energy Physics, Tsukuba, Ibaraki 305 (Japan)

1997-09-01

347

Measurements for the energy and flux of laser Compton scattering ?-ray photons generated in an electron storage ring: NewSUBARU  

NASA Astrophysics Data System (ADS)

The maximum energy and flux of laser Compton scattering gamma ray photons generated in the electron storage ring NewSUBARU by CO 2 (˜10.6 ?m) and Nd (1.064 ?m, 0.532 ?m) laser beams were measured with a Ge detector calibrated by gamma rays from radioisotopes and a GSO detector, respectively. The electron beam energy derived from the measured maximum gamma ray energy agreed fairly well with the electron beam energy derived from the physical parameters for bending electromagnets in NewSUBARU. The maximum normalized flux for gamma ray photons was found to be 6.0×10 3 (±5%) photons W -1 mA -1 s -1 at the beam hatch. For a stored current of 200 mA and a Nd laser output of 4.2 W, the photon flux was measured to be 5.0×10 6 photons s -1. These values were well reproduced through theoretical calculations. Calculations for the laser alignment accuracies showed that the separation between the electron and laser beam axes and the beam cross angle between them are required to be less than 0.2 mm and 0.2 mrad, respectively, to suppress the reduction of the maximum photon flux in less than 10%.

Horikawa, Ken; Miyamoto, Shuji; Amano, Sho; Mochizuki, Takayasu

2010-06-01

348

Observations of gamma radiation between 0. 4 MeV and 7 MeV at balloon altitudes using a Compton telescope  

SciTech Connect

Results are presented from a balloon flight at Palestine, Texas, in 1978 to measure the atmospheric and diffuse ..gamma..-ray flux in the energy range 0.4--7.0 MeV. The observations were made with a Compton telescope which included pulse-shape discrimination of the first scattering detector and a time-of-flight system between the first and second detector elements. The total downward ..gamma..-ray flux at 3.7 g cm/sup -2/ is given by the spectrum 3.1 x 10/sup -2/ x E/sup -1.74/ (photons cm/sup -2/ s/sup -1/ MeV/sup -1/ sr/sup -1/) for 0.5gamma..-ray flux to the atmospheric ..gamma..-rays indicate that 0.2 MeV

Lockwood, J.A.; Webber, W.R.; Friling, L.A.; Macri, J.; Hsieh, L.

1981-09-15

349

The Operation Modes of Kharkov X-Ray Generator Based on Compton Scattering NESTOR  

SciTech Connect

The results of theoretical and numerical considerations of linear Compton scattering are used to evaluate characteristics of X-rays produced by collision between a low emittance electron beam and intensive laser light in an X-ray generator NESTOR of NSC KIPT. Two main generation modes have been under consideration at preliminary NESTOR design. There are the operation mode for medicine 33.4 keV X-rays production using 43 Mev electron beam and Nd:YAG laser beam and higher energy X-rays production mode providing X-rays with energy up to 900 keV with 225 MeV electron beam and Nd:YAG laser beam. It was supposed to use an optical cavity for laser beam accumulation of about 2.6 m long and an interaction angle of about 3{sup o} in both operation modes. A few more operation modes provide possibility to expand operation range of NESTOR. Using interaction angle 10{sup o} and 150{sup o} along with optical resonator of 42 cm long and the second mode of laser light it is possible to produce X-rays in energy range from a few keV till 1.5 MeV. The intensity and spectral brightness of the X-rays is expected to be {approx} 10{sup 13} phot/s and {approx}10{sup 13} phot/s/mm{sup 2}/mrad{sup 2}/0.1%BW respectively.

Bulyak, E.V.; Gladkikh, P.; Karnaukhov, I.M.; Mytsykov, A.; Shcherbakov, A.A.; Zelinsky, A.Y.; /Kharkov, KIPT; Tatchyn, R.; /SLAC, SSRL

2005-05-09

350

CONSTRAINT ON THE PARAMETERS OF THE INVERSE COMPTON SCATTERING MODEL FOR RADIO PULSARS  

SciTech Connect

The inverse Compton scattering (ICS) model can explain various pulse profile shapes and the diversity of the pulse profile evolution based on the mechanism where the radio emission is generated through ICS between secondary relativistic particles and radio waves from polar gap avalanches. In this paper, we study the parameter space of the ICS model for 15 pulsars that share the common pulse profile evolution phenomenon, where the pulse profiles are narrower at higher observing frequencies. Two key parameters, the initial Lorentz factor and the energy loss factor of secondary particles, are constrained using the least-squares fitting method, where we fit the theoretical curve of the 'beam-frequency mapping' of the ICS model to the observed pulse widths at multiple frequencies. The uncertainty of the inclination and viewing angles are taken into account in the fitting process. It is found that the initial Lorentz factor is larger than 4000, and the energy loss factor is between 20 and 560. The Lorentz factor is consistent with the prediction of the inner vacuum gap model. Such high-energy loss factors suggest significant energy loss for secondary particles at altitudes of a few tens to hundreds of kilometers.

Lv, M.; Wang, H. G. [Center for Astrophysics, Guangzhou University, Guangzhou 510006 (China); Lee, K. J. [Max-Planck Institute for Radio Astronomy, Bonn 53121 (Germany); Qiao, G. J.; Xu, R. X., E-mail: hgwang@gzhu.edu.cn [Department of Astronomy, Peking University, Beijing 100871 (China)

2011-11-01

351

Inverse Compton scattering of coherent synchrotron radiation in an energy recovery linac  

NASA Astrophysics Data System (ADS)

We propose inverse Compton scattering (ICS) of coherent synchrotron radiation (CSR) from a relativistic short electron bunch in energy recovery linacs (ERL) as a high-flux subpicosecond x-ray and ?-ray source. An advantage of the CSR scheme over a conventional ICS source is that no external laser is required, and synchronization between CSR pulses and electron bunches is obtained automatically. Moreover, higher-flux x rays can be generated from the ICS of CSR in an ERL operated at a high repetition rate, 100 MHz to 1.3 GHz. Using parameters of the Compact ERL at KEK, 1×1013-14phs/s b.w. 10% (the number of photons pulse-1 bandwidth unit-1) x ray with a 100 fs-1 ps pulse duration can be obtained, for an energy range from 0.04 to 4 keV. In the case of a 5-GeV ERL, ? rays with energy around tens of MeV are generated with 1×108phs/pulse b.w. 10% at a repetition rate of several hundreds of MHz.

Shimada, M.; Hajima, R.

2010-10-01

352

Development of a 4-mirror optical cavity for an inverse Compton scattering experiment in the STF  

NASA Astrophysics Data System (ADS)

To obtain high-brightness quasi-monochromatic X-rays via inverse Compton scattering (ICS), an optical cavity for intensifying laser beams was designed and implemented in a new beam line at the KEK Superconducting RF Test Facility (STF) accelerator. The optical cavity adopts a planar configuration consisting of 4 mirrors. This confocal type resonator provides stable laser storage even with a long mirror distance, enabling head-on collision with the electron beams. To overcome the well-known astigmatism problems of the planar-type optical cavity, two forcibly bendable cylindrical mirrors were introduced instead of flat mirrors. With this new function for laser profile adjustment, an almost round laser profile at the waist point in the accelerator environment was successfully achieved. Estimated waist sizes were 43.7 ?m for the horizontal and 50.8 ?m for the vertical dimensions. The feedback control of this 4-mirror optical cavity worked with a stiff plate supporting all 4 mirrors. 1.7×103 finesse and 2.8-kW stored power for a 1-ms duration with 5 Hz were achieved.

Shimizu, Hirotaka; Aryshev, Alexander; Higashi, Yasuo; Honda, Yosuke; Urakawa, Junji

2014-05-01

353

Determination of electron beam parameters by means of laser-Compton scattering  

NASA Astrophysics Data System (ADS)

Laser-Compton scattering (LCS) experiments were carried out at the Idaho Accelerator Center using the 5 ns (FWHM) and 22 MeV electron beam. The electron beam was brought to an approximate head-on collision with a 29 MW, 7 ns (FWHM), 10 Hz Nd:YAG laser. Clear and narrow x-ray peaks resulting from the interaction of relativistic electrons with the Nd:YAG laser second harmonic line at 532 nm were observed. We have developed a relatively new method of using LCS as a nonintercepting electron beam monitor. Our method focused on the variation of the shape of the LCS spectrum rather than the LCS intensity as a function of the observation angle in order to extract the electron beam parameters at the interaction region. The electron beam parameters were determined by making simultaneous fits to spectra taken across the LCS x-ray cone. This scan method allowed us also to determine the variation of LCS x-ray peak energies and spectral widths as a function of the detector angles. Experimental data show that in addition to being viewed as a potential bright, tunable, and quasimonochromatic x-ray source, LCS can provide important information on the electron beam pulse length, direction, energy, angular and energy spread. Since the quality of LCS x-ray peaks, such as degree of monochromaticity, peak energy and flux, depends strongly on the electron beam parameters, LCS can therefore be viewed as an important nondestructive tool for electron beam diagnostics.

Chouffani, K.; Harmon, F.; Wells, D.; Jones, J.; Lancaster, G.

2006-05-01

354

X-ray imaging with laser-Compton scattering X-ray at AIST  

NASA Astrophysics Data System (ADS)

An X-ray facility with a compact electron linear accelerator via laser-Compton scattering (LCS X-ray) is recently installed at AIST. The LCS X-ray facility in approximately 8-m square consists of a 40-MeV linac, a femtosecond terawatt laser and an X-ray beamline. The LCS X-ray facility produces quasi-monochromatic X-rays with energy in the range of 12 ~ 40 keV which are commonly used in many studies currently carried out at synchrotron radiation facilities. The LCS X-ray is suitable for phase-contrast imaging such as in-line method, diffraction-enhanced imaging method, X-ray interferometry method, because of the quasi-monochoromaticity and the small source size. These advantages produce much clearer image of weakly absorbing specimens in the radiography of clinical and industrial application. Here we report on the feasibility study of the in-line phase-contrast imaging of biological samples using the LCS X-ray. Our experimental arrangement is widely used in the in-line method. The weakly absorbing parts of the samples are successfully imaged under the phase-contrast condition.

Yasumoto, M.; Kuroda, R.; Ikeura-Sekiguchi, H.; Toyokawa, H.; Sei, N.; Ogawa, H.; Koike, M.; Yamada, K.; Mori, K.; Sakai, F.; Tamura, S.

2009-09-01

355

An X-ray spectroscopy system and its application to the laser-Compton scattering experiments  

NASA Astrophysics Data System (ADS)

One of the main challenges for the laser-Compton scattering (LCS) experiments with the oblique configuration at the Linac of SINAP is the low signal to noise ( S/N) ratio due to the low intensity of LCS signals. X-ray spectroscopy system mainly consisting of an X-ray Si(Li) detector, electronics, and LabVIEW-based data acquisition has been developed for the low S/N ratio experiments. Spectral characteristics of such a system (i.e., energy and time resolutions, data acquisition efficiency, and system instability) have been determined by the 55Fe, 241Am, and 238Pu radioactive sources. In order to extract the LCS X-ray spectrum, several methods for the enhancement of the S/N ratio have been achieved and data have been taken alternatively with laser pulse on and off. Thanks to these methods the S/ N ratios have been optimized. Finally, the generated LCS X-ray spectrum has been achieved through the subtraction of the on/off laser accumulated spectra.

Luo, W.; Xu, W.; Pan, Q. Y.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Xu, B. J.; Xu, Y.; Yan, Z.; Yang, L. F.

2010-12-01

356

Trajectory Design and Control for the Compton Gamma Ray Observatory Re-Entry  

NASA Technical Reports Server (NTRS)

The Compton Gamma Ray Observatory (CGRO) controlled re-entry operation was successfully conducted in June of 2000. The surviving parts of the spacecraft landed in the Pacific Ocean within the predicted footprint. The design of the maneuvers to control the trajectory to accomplish this re-entry presented several challenges. These challenges included timing and duration of the maneuvers, fuel management, post maneuver position knowledge, collision avoidance with other spacecraft, accounting for the break-up of the spacecraft into several pieces with a wide range of ballistic coefficients, and ensuring that the impact footprint would remain within the desired landing area in the event of contingencies. This paper presents the initial re-entry trajectory design and the evolution of the design into the maneuver sequence used for the re-entry. The paper discusses the constraints on the trajectory design, the modifications made to the initial design and the reasons behind these modifications. Data from the re-entry operation are presented.

Hoge, Susan; Vaughn, Frank; Bauer, Frank H. (Technical Monitor)

2000-01-01

357

Trajectory Design and Control for the Compton Gamma Ray Observatory Re-Entry  

NASA Technical Reports Server (NTRS)

The Compton Gamma Ray Observatory (CGRO) controlled re-entry operation was successfully conducted in June of 2000. The surviving parts of the spacecraft landed in the Pacific Ocean within the nominal impact target zone. The design of the maneuvers to control the trajectory to accomplish this re-entry presented several challenges. These challenges included the timing and duration of the maneuvers, propellant management, post-maneuver state determination, collision avoidance with other spacecraft, accounting for the break-up of the spacecraft into several pieces with a wide range of ballistic coefficients, and ensuring that the impact footprint would remain within the desired impact target zone in the event of contingencies. This paper presents the initial re-entry trajectory design and traces the evolution of that design into the maneuver sequence used for the re-entry. The paper also discusses the spacecraft systems and operational constraints imposed on the trajectory design and the required modifications to the initial design based on those constraints. Data from the reentry operation are also presented.

Hoge, Susan; Vaughn, Frank J., Jr.

2001-01-01

358

A 4D Monte Carlo laser-Compton scattering simulation code for the characterization of the future energy-tunable SLEGS  

NASA Astrophysics Data System (ADS)

For the full determination of the characteristics of laser-Compton X/?-ray source, a four-dimensional (three-dimensional time and frequency-domain) Monte Carlo laser-Compton scattering simulation code has been developed with Geant4 toolkit. The code has the capability to calculate the spatial, spectral and temporal characteristics of the LCS X/?-ray source with slanting collision configuration. This capability is crucial for both the design of successful LCS X/?-ray source, as well as future experiments and applications utilizing this kind of sources. In this paper, the algorithm of the code and its benchmark processes are presented in detail. To benchmark the code, the X/?-ray data taken from the worldwide and typical LCS facilities, such as HI?S at Duke University and PLEIADES at LLNL are compared to the simulated results. The benchmark processes show that the simulated results are consistent with the measurements. Utilizing the code, partial characteristics of Shanghai laser electron gamma source (SLEGS) are studied as well. The SLEGS is expected to be an energy tunable ?-ray source with its maximum energy adjustable from tens MeV to hundreds MeV and its photon flux of 10 5-10 6 photons/s if a 1-mJ/pulse, 1-kHz Ti:Sa laser system is employed.

Luo, W.; Xu, W.; Pan, Q. Y.; An, Z. D.; Cai, X. L.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Xu, B. J.; Yan, Z.; Yang, L. F.

2011-12-01

359

Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors  

PubMed Central

A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm2 area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm3. The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(GAMOS) and the Origin Ensemble(OE) algorithm is used for the image reconstruction. The simulation shows that the camera can operate with up to 104 Bq source activities with equal efficiency and is completely saturated at 109 Bq. The efficiency of the system is evaluated using a simulated 18F point source phantom in the center of the Field-of-View (FOV) achieving an intrinsic efficiency of 0.4 counts per second per kilobecquerel. The spatial resolution measured from the point spread function (PSF) shows a FWHM of 1.5 mm along the direction perpendicular to the scatterer, making it possible to distinguish two points at 3 mm separation with a peak-to-valley ratio of 8.

Calderon, Y.; Chmeissani, M.; Kolstein, M.; De Lorenzo, G.

2014-01-01

360

Efficient Propagation of Polarization from Laser Photons to Positrons through Compton Scattering and Electron-Positron Pair Creation  

SciTech Connect

We have demonstrated for the first time the production of highly polarized short-pulse positrons with a finite energy spread in accordance with a new scheme that consists of two-quantum processes, such as inverse Compton scattering and electron-positron pair creation. Using a circularly polarized laser beam of 532 nm scattered off a high-quality, 1.28 GeV electron beam, we have obtained polarized positrons with an intensity of 2x10{sup 4} e{sup +}/bunch. The magnitude of positron polarization has been determined to be 73{+-}15(stat){+-}19(syst)% by means of a newly designed positron polarimeter.

Omori, T.; Kurihara, Y.; Okugi, T.; Urakawa, J. [KEK: High Energy Accelerator Research Organization, Tsukuba-shi, Ibaraki 305-0801 (Japan); Fukuda, M.; Nomura, M. [National Institute of Radiological Sciences, Chiba-shi, Chiba 263-8555 (Japan); Hirose, T.; Sakaue, K.; Saito, T.; Washio, M.; Yamazaki, I. [Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); Kuroda, R. [Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555 (Japan); National Institute of Advanced Industrial Science and Technology, Tsukuba-shi, Ibaraki 305-8568 (Japan); Ohashi, A. [Department of Physics, Tokyo Metropolitan Univeresity, Hachioji-shi, Tokyo 192-0397 (Japan)

2006-03-24

361

Transmutation of nuclear wastes using photonuclear reactions triggered by Compton backscattering photons at the Shanghai laser electron gamma source  

NASA Astrophysics Data System (ADS)

Based on the facility of the Shanghai Laser Electron Gamma Source (SLEGS), the transmutation for nuclear wastes such as 137Cs and 129I is investigated. It is found that nuclear waste can be transmuted efficiently via photonuclear reaction triggered by gamma photons generated from Compton backscattering between CO2 laser photons and 3.5 GeV electrons. The nuclear activities of 137Cs and 129I are evaluated and compared with the results of transmutation triggered by bremsstrahlung gamma photons driven by ultra intense laser. Due to the better character of gamma photon spectrum as well as the high brightness of gamma photons, the transmutation rate of Compton backscattering method is much higher than that of the bremsstrahlung method. Supported by Knowledge Innovation Project of Chinese Academy of Sciences (KJCX2-SW-N13), China Postdoctoral Science Foundation, National Natural Science Foundation of China (10475108, 10605036, 10405032), One Hundred Person Project of SINAP, and Shanghai Development Foundation for Science and Technology (06QA14062)

Chen, Jin-Gen; Xu, Wang; Wang, Hong-Wei; Guo, Wei; Ma, Yu-Gang; Cai, Xiang-Zhou; Lu, Guang-Cheng; Xu, Yi; Pan, Qiang-Yan; Yuan, Ren-Yong; Xu, Jia-Qiang; Yan, Zhe; Fan, Gong-Tao; Shen, Wen-Qing

2008-08-01

362

Improvement of gamma-ray S{sub n} transport calculations including coherent and incoherent scatterings and secondary sources of bremsstrahlung and fluorescence: Determination of gamma-ray buildup factors  

Microsoft Academic Search

Improvements of gamma-ray transport calculations in S{sub n} codes aim at taking into account the bound-electron effect of Compton scattering (incoherent), coherent scattering (Rayleigh), and secondary sources of bremsstrahlung and fluorescence. A computation scheme was developed to take into account these phenomena by modifying the angular and energy transfer matrices, and no modification in the transport code has been made.

S. Kitsos; C. M. Diop; A. Assad; J. C. Nimal; P. Ridoux

1996-01-01

363

Measurements of the Electron-Helicity Dependent Cross Sections of Deeply Virtual Compton Scattering with CEBAF at 12 GeV  

SciTech Connect

We propose precision measurements of the helicity-dependent and helicity independent cross sections for the ep {yields} ep{gamma} reaction in Deeply Virtual Compton Scattering (DVCS) kinematics. DVCS scaling is obtained in the limits Q{sup 2} >> {Lambda}{sub QCD}{sup 2}, x{sub Bj} fixed, and -{Delta}{sup 2} = -(q-q{prime}){sup 2} << Q{sup 2}. We consider the specific kinematic range Q{sup 2} > 2 GeV{sup 2}, W > 2 GeV, and -{Delta}{sup 2} {le} 1 GeV{sup 2}. We will use our successful technique from the 5.75 GeV Hall A DVCS experiment (E00-110). With polarized 6.6, 8.8, and 11 GeV beams incident on the liquid hydrogen target, we will detect the scattered electron in the Hall A HRS-L spectrometer (maximum central momentum 4.3 GeV/c) and the emitted photon in a slightly expanded PbF{sub 2} calorimeter. In general, we will not detect the recoil proton. The H(e,e{prime}{gamma})X missing mass resolution is sufficient to isolate the exclusive channel with 3% systematic precision.

J. Roche; C. E. Hyde-Wright; B. Michel; C. Munoz Camacho; et al. (The Jefferson Lab Hall A Collaboration)

2006-09-11

364

Magnetic Compton scattering study of Ni2+xMn1-xGa ferromagnetic shape-memory alloys  

NASA Astrophysics Data System (ADS)

In this paper, we report the spin-polarized momentum densities of Ni2+xMn1-xGa ( x=0.03 , 0.26, and 0.35) Heusler alloys at various temperatures and magnetic fields using magnetic Compton scattering technique. Magnetization studies are also performed for comparison. It is seen that the variation of magnetic effect (ratio of magnetic to charge intensities) is consistent with the martensitic transition, as shown by the differential scanning calorimetry data. The magnetic Compton profiles have been analyzed mainly in terms of the contributions from the 3d electrons of Mn to determine their role in the formation of total spin moment. The full potential linearized augmented plane-wave method has been used to calculate the spin-polarized energy bands and the spin moments of Ni2MnGa and Ni2.25Mn0.75Ga . Ni2MnGa exhibits half metallicity along certain high-symmetry directions of the Brillouin zone. For Ni2MnGa , the total and Mn local moments obtained from Compton scattering are in excellent agreement with theory.

Ahuja, B. L.; Sharma, B. K.; Mathur, S.; Heda, N. L.; Itou, M.; Andrejczuk, A.; Sakurai, Y.; Chakrabarti, Aparna; Banik, S.; Awasthi, A. M.; Barman, S. R.

2007-04-01

365

Constraints on dark matter annihilation from M87. Signatures of prompt and inverse-Compton gamma rays  

NASA Astrophysics Data System (ADS)

As the largest mass concentrations in the local Universe, nearby clusters of galaxies and their central galaxies are prime targets in searching for indirect signatures of dark matter annihilation (DMA). We seek to constrain the dark matter annihilation emission component from multi-frequency observations of the central galaxy of the Virgo cluster. The annihilation emission component is modeled by the prompt and inverse-Compton gamma rays from the hadronization of annihilation products from generic weakly interacting dark matter particles. This component is fitted to the excess of the observed data above the spectral energy distribution (SED) of the jet in M87, described with a best-fit synchrotron-self-Compton (SSC) spectrum. While this result is not sufficiently significant to claim a detection, we emphasize that a dark matter "double hump signature" can be used to unambiguously discriminate the dark matter emission component from the variable jet-related emission of M87 in future, more extended observation campaigns.

Saxena, Sheetal; Summa, Alexander; Elsässer, Dominik; Rüger, Michael; Mannheim, Karl

2011-11-01

366

The Role of Inverse Compton Scattering in Solar Coronal Hard X-Ray and ?-Ray Sources  

NASA Astrophysics Data System (ADS)

Coronal hard X-ray (HXR) and continuum ?-ray sources associated with the impulsive phase of solar flares have been the subject of renewed interest in recent years. They have been interpreted in terms of thin-target, non-thermal bremsstrahlung emission. This interpretation has led to rather extreme physical requirements in some cases. For example, in one case, essentially all of the electrons in the source must be accelerated to non-thermal energies to account for the coronal HXR source. In other cases, the extremely hard photon spectra of the coronal continuum ?-ray emission suggest that the low-energy cutoff of the electron energy distribution lies in the MeV energy range. Here, we consider the role of inverse Compton scattering (ICS) as an alternate emission mechanism in both the ultra- and mildly relativistic regimes. It is known that relativistic electrons are produced during powerful flares; these are capable of upscattering soft photospheric photons to HXR and ?-ray energies. Previously overlooked is the fact that mildly relativistic electrons, generally produced in much greater numbers in flares of all sizes, can upscatter extreme-ultraviolet/soft X-ray photons to HXR energies. We also explore ICS on anisotropic electron distributions and show that the resulting emission can be significantly enhanced over an isotropic electron distribution for favorable viewing geometries. We briefly review results from bremsstrahlung emission and reconsider circumstances under which non-thermal bremsstrahlung or ICS would be favored. Finally, we consider a selection of coronal HXR and ?-ray events and find that in some cases the ICS is a viable alternative emission mechanism.

Chen, Bin; Bastian, T. S.

2012-05-01

367

X-ray Fluorescence (XRF) Assay Using Laser Compton Scattered (LCS) X-rays  

SciTech Connect

Laser Compton Scattered (LCS) X-rays are produced as a result of the interaction between accelerated electrons and a laser beam. The yield of LCS X-rays is dependent on the laser power, angle of collision between interacting particles, and the electron linear accelerator's (linac) electron beam energy and its current. One of our research goals at the Idaho Accelerator Center (IAC) focuses on applications such as detection and imaging of fissionable isotopes for nuclear non-proliferation, safeguards and homeland security. Quasi monochromatic LCS X-rays offer much better signal-to-noise ratios for such applications. The energy of LCS X-rays is tunable, that enable element-specific analysis. Two sharp 36.5 keV and 98.4 keV LCS peaks were observed in two separate experiments based on electron beams tuned at 32 MeV and 37 MeV, that were brought in collision with the (Power){sub peak} = 4 GW Nd.YAG laser operating at 532 nm and 266 nm wavelengths. The linac was operating at 60 Hz with an electron beam pulse length of about 50 ps and a peak current of about 7 A. We exploited X-ray fluorescence (XRF) techniques to identify elemental K{alpha}{sub 1}, K{alpha}{sub 2}, and K{beta}{sub 1} lines in a high-purity germanium (HPGe) detector, with a 0.5 mm thick Beryllium (Be) absorbing layer, emitted from tin (Sn), cadmium (Cd), silver (Ag), gold (Au), and lead (Pb) foils with thicknesses ranging from 25-500 {mu}m, following absorption of 36.1 keV and 98.4 keV LCS X-rays. These reference foils were used for the proof of principle, and some have atomic numbers near to that of relevant fission products.

Naeem, Syed F.; Chouffani, Khalid; Wells, Douglas P. [Idaho State University, Idaho Accelerator Center, Campus Box 8263, Pocatello ID 83209 (United States)

2009-03-10

368

Multi-Beam Compton Scattering Monochromatic Tunable Hard X-Ray Source  

NASA Astrophysics Data System (ADS)

Compton scattering hard X-ray source which consists of an X-band (11.424 GHz) electron linear accelerator and YAG laser is under construction at Nuclear Professional School, the University of Tokyo (UTNS). Monochromatic hard X-rays are required for variety of medical and biological applications. Our scheme of the hard X-ray source is to produce a monochromatic hard X-ray via collision between 35 MeV electron beam and 2.5 J/10 nsec Nd:YAG laser. In order to increase the efficiency of the X-ray yield, we adopt a laser pulse circulation system. In our case, the laser pulse circulation system can increase the X-ray intensity of up to 50 times. Main features of our scheme are to produce monochromatic tunable hard (10-40 keV) X-rays with the intensities of 108-109 photons/sec. In addition, X-ray energy can be changed with rapidly by 40 ms by introducing two different wavelength lasers (YAG fundamental (1064 nm), 2nd harmonic (532 nm)) and optical switch. This quick energy change is indispensable to living specimens and very difficult by a large SR light source and others. We designed a laser pulse circulation system to increase the X-ray yield 10 times higher (up to 108 photons/RF pulse, 109 photons/sec). It can be proved that the laser total increases 10 times higher by principle experiment with lower energy laser (25 mJ/pulse). Dual-energy X-ray CT and subtraction X-ray CT are available to determine 3D distribution of atomicc number density and electron density, and specified atomic distribution, respectively. Here, the construction status of the X-band beam line and the application plan of the hard X-ray will be reported.

Uesaka, Mitsuru; Sakamoto, Fumito; Fukasawa, Atsushi; Ogino, Haruyuki; Yamamoto, Tomohiko; Meng, De; Dobashi, Katsuhiro; Miyoshi, Toshinobu; Higo, Toshiyasu; Akemoto, Mitsuo; Urakawa, Junji

369

X-ray Fluorescence (XRF) Assay Using Laser Compton Scattered (LCS) X-rays  

NASA Astrophysics Data System (ADS)

Laser Compton Scattered (LCS) X-rays are produced as a result of the interaction between accelerated electrons and a laser beam. The yield of LCS X-rays is dependent on the laser power, angle of collision between interacting particles, and the electron linear accelerator's (linac) electron beam energy and its current. One of our research goals at the Idaho Accelerator Center (IAC) focuses on applications such as detection and imaging of fissionable isotopes for nuclear non-proliferation, safeguards and homeland security. Quasi monochromatic LCS X-rays offer much better signal-to-noise ratios for such applications. The energy of LCS X-rays is tunable, that enable element-specific analysis. Two sharp 36.5 keV and 98.4 keV LCS peaks were observed in two separate experiments based on electron beams tuned at 32 MeV and 37 MeV, that were brought in collision with the (Power)peak = 4 GW Nd.YAG laser operating at 532 nm and 266 nm wavelengths. The linac was operating at 60 Hz with an electron beam pulse length of about 50 ps and a peak current of about 7 A. We exploited X-ray fluorescence (XRF) techniques to identify elemental K?1, K?2, and K?1 lines in a high-purity germanium (HPGe) detector, with a 0.5 mm thick Beryllium (Be) absorbing layer, emitted from tin (Sn), cadmium (Cd), silver (Ag), gold (Au), and lead (Pb) foils with thicknesses ranging from 25-500 ?m, following absorption of 36.1 keV and 98.4 keV LCS X-rays. These reference foils were used for the proof of principle, and some have atomic numbers near to that of relevant fission products.

Naeem, Syed F.; Chouffani, Khalid; Wells, Douglas P.

2009-03-01

370

Compton-scattering measurement of diagnostic x-ray spectrum using high-resolution Schottky CdTe detector  

SciTech Connect

The analysis of x-ray spectra is important for quality assurance (QA) and quality control (QC) of radiographic systems. The aim of this study is to measure the diagnostic x-ray spectra under clinical conditions using a high-resolution Schottky CdTe detector. Under clinical conditions, the direct measurement of a diagnostic spectrum is difficult because of the high photon fluence rates that cause significant detector photon pile-up. An alternative way of measuring the output spectra from a tube is first to measure the 90 deg Compton scattered photons from a given sample. With this set-up detector, pile-up is not a problem. From the scattered spectrum one can then use an energy correction and the Klein-Nishina function to reconstruct the actual spectrum incident upon the scattering sample. The verification of whether our spectra measured by the Compton method are accurate was accomplished by comparing exposure rates calculated from the reconstructed spectra to those measured with an ionization chamber. We used aluminum (Al) filtration ranging in thickness from 0 to 6 mm. The half value layers (HVLs) obtained for a 70 kV beam were 2.78 mm via the ionization chamber measurements and 2.93 mm via the spectral measurements. For a 100 kV beam we obtained 3.98 and 4.32 mm. The small differences in HVLs obtained by both techniques suggest that Compton scatter spectroscopy with a Schottky CdTe detector is suitable for measuring the diagnostic x-ray spectra and useful for QA and QC of clinical x-ray equipment.

Maeda, Koji; Matsumoto, Masao; Taniguchi, Akira [Department of Clinical Radiology, Faculty of Health Sciences, Hiroshima International University, 555-36 Gakuen-dai, Kurose-cho, Kamo-gun, Hiroshima 724-0695 (Japan); Division of Health Sciences, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka 565-0871 (Japan); Environment Technology Division, Toyo Medic Co. Ltd., 1-17-22 Kitahorie, Nishi-ku, Osaka 550-0014 (Japan)

2005-06-15

371

Neutron Compton scattering from the super proton conductor H3OSbTeO6 and polyethylene: a comparison of proton momentum distributions and reduced cross-sections  

Microsoft Academic Search

Neutron Compton scattering (NCS) results at large momentum transfers (q≈60-130 Å-1) obtained from the super proton conductor H3OSbTeO6 (powder at T = 295 K) are compared with those obtained from polyethylene (PE, foil at T = 295 K). The Compton profiles of protons in both systems are approximately Gaussians with equal widths, sigmaH≈5 Å-1, within experimental error, thus indicating that

C. A. Chatzidimitriou-Dreismann; M. Krzystyniak; T. Abdul-Redah; M. Lerch

2007-01-01

372

GRAPE: A Compton Polarimetry Experiment  

NASA Astrophysics Data System (ADS)

We review the design, calibration and data analysis of the Gamma Ray Polarimetry Experiment (GRAPE), a Compton polarimeter device for measuring the polarization of photons in the 50-500 keV energy range. In Compton scattering, X-ray and gamma-ray photons tend to scatter at right angles with respect to their polarization vector. We exploit this fact to measure the polarization of the incident radiation by looking at the azimuthal distribution of the scattered photons. This distribution gives us a measure of both the level of polarization and the orientation of the polarization vector. These measurements will allow us to probe the particle acceleration regions of astronomical sources. GRAPE will be flown in the fall of 2011 on as a high altitude balloon payload. The primary target of that flight will be the Crab Nebula, with the Sun (solar flares) and Cygnus X-1 as secondary targets. Our observations of the Crab will be compared to the findings of the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL), which provided constraints on the location of the particle acceleration region within the Crab Nenbula. Following the initial flight in 2011, we hope to fly GRAPE on a long duration balloon flight from Antarctica to study gamma-ray bursts.

Connor, Taylor; Bloser, Peter; Legere, Jason; McConnell, Mark; Ryan, James

2009-10-01

373

Inverse Compton scattering of ambient radiation by a cold relativistic jet - A source of beamed, polarized continuum in blazars?  

NASA Technical Reports Server (NTRS)

A general formalism is developed for computing the intensity and polarization of unpolarized radiation scattered by a group of electrons with a specified distribution of momenta. The case of isotropic incident radiation with a power-law spectrum is addressed, and the 'head-on' approximation is developed to describe the nearly unidirectional character of the incident radiation in the electron rest frame. The formalism is implemented numerically, verifying the validity of the 'head-on' approximation and illustrating the polarization and intensity properties of radiation scattered by jets with different electron momentum distribution. The results are placed in an astrophysical setting, determining the optical depths and kinetic energies required for the scattered radiation to dominate over the isotropic component in blazars. It is argued that Comptonization of unbeamed AGN radiation by a relativistic jet can account for the polarization and the overall spectral shape of the IR-optical continuum in blazars.

Begelman, Mitchell C.; Sikora, Marek

1987-01-01

374

Virtual Compton scattering and neutral pion electroproduction in the resonance region up to the deep inelastic region at backward angles  

SciTech Connect

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e,e'p)? exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q2=1 GeV2, and for the Q2-dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q2-dependence is smooth. The measured ratio of H(e,e'p)? to H(e,e'p)?0 cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to Real Compton Scattering (RCS) at high energy and large angles, our VCS data at the highest W (1.8-1.9 GeV) show a striking Q2-independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.

Laveissiere, Geraud; Degrande, Natalie; Jaminion, Stephanie; Jutier, Christophe; Todor, Luminita; Di Salvo, Rachele; Van Hoorebeke, L.; Alexa, L.C.; Anderson, Brian; Aniol, Konrad; Arundell, Kathleen; Audit, Gerard; Auerbach, Leonard; Baker, F.; Baylac, Maud; Berthot, J.; Bertin, Pierre; Bertozzi, William; Bimbot, Louis; Boeglin, Werner; Brash, Edward; Breton, Vincent; Breuer, Herbert; Burtin, Etienne; Calarco, John; Cardman, Lawrence; Cavata, Christian; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chen, Jian-Ping; Chudakov, Eugene; Cisbani, Evaristo; Dale, Daniel; De Jager, Cornelis; De Leo, Raffaele; Deur, Alexandre; D'Hose, Nicole; Dodge, Gail; Domingo, John; Elouadrhiri, Latifa; Epstein, Martin; Ewell, Lars; Finn, John; Fissum, Kevin; Fonvieille, Helene; Fournier, Guy; Frois, Bernard; Frullani, Salvatore; Furget, Christophe; Gao, Haiyan; Gao, Juncai; Garibaldi, Franco; Gasparian, Ashot; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Glashausser, Charles; Gomez, Javier; Gorbenko, Viktor; Grenier, Philippe; Guichon, Pierre; Hansen, Jens-Ole; Holmes, Richard; Holtrop, Maurik; Howell, Calvin; Huber, Garth; Hyde, Charles; Incerti, Sebastien; Iodice, Mauro; Jardillier, Johann; Jones, Mark; Kahl, William; Kamalov, Sabit; Kato, Seigo; Katramatou, A.T.; Kelly, James; Kerhoas, Sophie; Ketikyan, Armen; Khayat, Mohammad; Kino, Kouichi; Kox, Serge; Kramer, Laird; Kumar, Krishna; Kumbartzki, Gerfried; Kuss, Michael; Leone, Antonio; LeRose, John; Liang, Meihua; Lindgren, Richard; Liyanage, Nilanga; Lolos, George; Lourie, Robert; Madey, Richard; Maeda, Kazushige; Malov, Sergey; Manley, D.; Marchand, Claude; Marchand, Dominique; Margaziotis, Demetrius; Markowitz, Pete; Marroncle, Jacques; Martino, Jacques; McCormick, Kathy; McIntyre, Justin; Mehrabyan, Surik; Merchez, Fernand; Meziani, Zein-Eddine; Michaels, Robert; Miller, Gerald; Mougey, Jean; Nanda, Sirish; Neyret, Damien; Offermann, Edmond; Papandreou, Zisis; Perdrisat, Charles; Perrino, R.; Petratos, Gerassimos; Platchkov, Stephane; Pomatsalyuk, Roman; Prout, David; Punjabi, Vina; Pussieux, Thierry; Quemener, Gilles; Ransome, Ronald; Ravel, Oliver; Real, Jean-Sebastien; Renard, F.; Roblin, Yves; Rowntree, David; Rutledge, Gary; Rutt, Paul; Saha, Arunava; Saito, Teijiro; Sarty, Adam; Serdarevic, A.; Smith, T.; Smirnov, G.; Soldi, K.; Sorokin, Pavel; Souder, Paul; Suleiman, Riad; Templon, Jeffrey; Terasawa, Tatsuo; Tiator, Lothar; Tieulent, Raphael; Tomasi-Gustaffson, E.; Tsubota, Hiroaki; Ueno, Hiroaki; Ulmer, Paul; Urciuoli, Guido; Van De Vyver, R.; van der Meer, Rob; Vernin, Pascal; Vlahovic, B.; Voskanyan, Hakob; Voutier, Eric; Watson, J.W.; Weinstein, Lawrence; Wijesooriya, Krishni; Wilson, R.; Wojtsekhowski, Bogdan; Zainea, Dan; Zhang, Wei-Ming; Zhao, Jie; Zhou, Z.-L.

2009-01-01

375

The results of the in-flight attitude sensor calibration for the Arthur Holly Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

The Arthur Holly Compton Gamma Ray Observatory (GRO) was launched by the shuttle Atlantis in April 1991. This paper presents the results of the attitude sensor calibration that was performed during the early mission. The GSFC Flight Dynamics Facility (FDF) performed an alignment calibration of the two fixed-head star trackers (FHST's) and two fine Sun sensors (FSS's) on board Compton GRO. The results show a 27-arcsecond shift between the bore sights of the FHST's with respect to prelaunch measurements. The alignments of the two FSS's shifted by 0.20 and 0.05 degree. During the same time period, the Compton GRO science teams performed an alignment calibration of the science instruments with respect to the attitude reported by the on board computer (OBC). In order to preserve these science alignments, FDF adjusted the overall alignments of the FHST's and FSS's, obtained by the FDF calibration, such that when up linked to the OBC, the shift in the OBC-determined attitude is minimized. FDF also calibrated the inertial reference unit (IRU), which consists of three dual-axis gyroscopes. The observed gyro bias matched the bias that was solved for by the OBC. This bias drifted during the first 6 days after release. The results of the FDF calibration of scale factor and alignment shifts showed changes that were of the same order as their uncertainties.

Davis, W. S.; Eudell, A. H.; Kulp, L. S.; Lindrose, L. A.; Harman, R. R.

1993-01-01

376

Nuclear-mass dependence of azimuthal beam-helicity and beam-charge asymmetries in deeply virtual Compton scattering  

SciTech Connect

The nuclear-mass dependence of azimuthal cross-section asymmetries with respect to charge and longitudinal polarization of the lepton beam is studied for hard exclusive electroproduction of real photons. The observed beam-charge and beam-helicity asymmetries are attributed to the interference between the Bethe-Heitler and the deeply virtual Compton scattering processes. For various nuclei, the asymmetries are extracted for both coherent and incoherent-enriched regions, which involve different (combinations of) generalized parton distributions. For both regions, the asymmetries are compared to those for a free proton, and no nuclear-mass dependence is found.

Airapetian, A. [Physikalisches Institut, Universitaet Giessen, D-35392 Giessen (Germany); Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States); Akopov, N.; Avakian, R.; Avetissian, A.; Elbakian, G.; Gharibyan, V.; Karyan, G.; Marukyan, H.; Movsisyan, A.; Taroian, S. [Yerevan Physics Institute, 375036 Yerevan (Armenia); Akopov, Z.; Avetisyan, E.; Borissov, A.; Hartig, M.; Holler, Y.; Rostomyan, A.; Schueler, K. P.; Varanda, M.; Ye, Z.; Zihlmann, B. [DESY, D-22603 Hamburg (Germany)

2010-03-15

377

Terawatt femtosecond laser storage cavity with cholesteric liquid crystals for an x-ray source based on Compton scattering.  

PubMed

In laser Compton scattering systems, the limitation to higher average brightness is the low repetition rate of high-power lasers. We propose and demonstrate for the first time, as far as we know, a simple method by which x-ray yield could be enhanced nearly 2 orders of magnitude per second. The method, utilizing cholesteric liquid crystals as the entrance mirror of the laser storage cavity, can be used not only for storing femtosecond laser pulses with a peak power of several terawatts, but also to make high coupling efficiency and energy utilization efficiency accessible. PMID:20436569

Hao, Xin; Zhu, Qi-hua; Zhang, Ying; Huang, Wan-qing; Geng, Yuan-chao; Wang, Xiao; Wang, Xiao-dong

2010-05-01

378

Photon Generation by Laser-Compton Scattering Using an Optical Resonant Cavity at the KEK-ATF Electron Ring  

NASA Astrophysics Data System (ADS)

We studied ?-ray generation by the laser-Compton scattering using a Fabry-Perot optical resonant cavity at the KEK-ATF electron storage ring. The laser power was enhanced up to 388 W in the optical resonant cavity with an injection power of 7 W in the ATF operation environments. The yield of photons for a crossing of a laser pulse and an electron bunch was 3.3± 0.6, which was consistent with a numerical estimate. In this paper, we report construction, installation and future prospect toward the polarized positron generation for the International Linear Collider.

Shimizu, Hirotaka; Araki, Sakae; Funahashi, Yoshisato; Honda, Yosuke; Okugi, Toshiyuki; Omori, Tsunehiko; Terunuma, Nobuhiro; Urakawa, Junji; Kuriki, Masao; Miyoshi, Shuhei; Takahashi, Tohru; Ushio, Yasuaki; Hirose, Tachishige; Sakaue, Kazuyuki; Washio, Masakazu; Guoxi, Pei; Li, XiaoPing

2009-07-01

379

X-ray bursting neutron star atmosphere models using an exact relativistic kinetic equation for Compton scattering  

NASA Astrophysics Data System (ADS)

Context. Theoretical spectra of X-ray bursting neutron star (NS) model atmospheres are widely used to determine the basic NS parameters such as their masses and radii. Compton scattering, which plays an important role in spectra formation at high luminosities, is often accounted for using the differential Kompaneets operator, while in other models a more general, integral operator for the Compton scattering kernel is used. Aims: We construct accurate NS atmosphere models using for the first time an exact treatment of Compton scattering via the integral relativistic kinetic equation. We also test various approximations to the Compton scattering redistribution function and compare the results with the previous calculations based on the Kompaneets operator. Methods: We solve the radiation transfer equation together with the hydrostatic equilibrium equation accounting exactly for the radiation pressure by electron scattering. We use the exact relativistic angle-dependent redistribution function as well as its simple approximate representations. Results: We thus construct a new set of plane-parallel atmosphere models in local thermodynamic equilibrium (LTE) for hot NSs. The models were computed for six chemical compositions (pure H, pure He, solar H/He mix with various heavy elements abundances Z = 1, 0.3, 0.1, and 0.01 Z?, and three surface gravities log g = 14.0, 14.3, and 14.6. For each chemical composition and surface gravity, we compute more than 26 model atmospheres with various luminosities relative to the Eddington luminosity LEdd computed for the Thomson cross-section. The maximum relative luminosities L/LEdd reach values of up to 1.1 for high gravity models. The emergent spectra of all models are redshifted and fitted by diluted blackbody spectra in the 3-20 keV energy range appropriate for the RXTE/PCA. We also compute the color correction factors fc. Conclusions: The radiative acceleration grad in our luminous, hot-atmosphere models is significantly smaller than in corresponding models based on the Kompaneets operator, because of the Klein-Nishina reduction of the electron scattering cross-section, and therefore formally "super-Eddington" model atmospheres do exist. The differences between the new and old model atmospheres are small for L/LEdd < 0.8. For the same grad/g, the new fc are slightly larger (by approximately 1%) than the old values. We also find that the model atmospheres, the emergent spectra, and the color correction factor computed using angle-averaged and approximate Compton scattering kernels differ from the exact solutions by less than 2%. Appendices are available in electronic form at http://www.aanda.orgTables D.1-D.3 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/545/A120

Suleimanov, V.; Poutanen, J.; Werner, K.

2012-09-01

380

Characterization and applications of a tunable, laser-based, MeV-class Compton-scattering ?-ray source  

NASA Astrophysics Data System (ADS)

A high peak brilliance, laser-based Compton-scattering ?-ray source, capable of producing quasimonoenergetic photons with energies ranging from 0.1 to 0.9 MeV has been recently developed and used to perform nuclear resonance fluorescence (NRF) experiments. Techniques for characterization of ?-ray beam parameters are presented. The key source parameters are the size (0.01mm2), horizontal and vertical divergence (6×10mrad2), duration (16 ps), and spectrum and intensity (105photons/shot). These parameters are summarized by the peak brilliance, 1.5×1015photons/mm2/mrad2/s/0.1% bandwidth, measured at 478 keV. Additional measurements of the flux as a function of the timing difference between the drive laser pulse and the relativistic photoelectron bunch, ?-ray beam profile, and background evaluations are presented. These results are systematically compared to theoretical models and computer simulations. NRF measurements performed on Li7 in LiH demonstrate the potential of Compton-scattering photon sources to accurately detect isotopes in situ.

Albert, F.; Anderson, S. G.; Gibson, D. J.; Hagmann, C. A.; Johnson, M. S.; Messerly, M.; Semenov, V.; Shverdin, M. Y.; Rusnak, B.; Tremaine, A. M.; Hartemann, F. V.; Siders, C. W.; McNabb, D. P.; Barty, C. P. J.

2010-07-01

381

THE {gamma}-RAY SPECTRUM OF GEMINGA AND THE INVERSE COMPTON MODEL OF PULSAR HIGH-ENERGY EMISSION  

SciTech Connect

We reanalyze the Fermi spectra of the Geminga and Vela pulsars. We find that the spectrum of Geminga above the break is well approximated by a simple power law without the exponential cutoff, making Geminga's spectrum similar to that of Crab. Vela's broadband {gamma}-ray spectrum is equally well fit with both the exponential cutoff and the double power-law shapes. In the broadband double power-law fits, for a typical Fermi spectrum of a bright {gamma}-ray pulsar, most of the errors accumulate due to the arbitrary parameterization of the spectral roll-off. In addition, a power law with an exponential cutoff gives an acceptable fit for the underlying double power-law spectrum for a very broad range of parameters, making such fitting procedures insensitive to the underlying Fermi photon spectrum. Our results have important implications for the mechanism of pulsar high-energy emission. A number of observed properties of {gamma}-ray pulsars-i.e., the broken power-law spectra without exponential cutoffs and stretching in the case of Crab beyond the maximal curvature limit, spectral breaks close to or exceeding the maximal breaks due to curvature emission, patterns of the relative intensities of the leading and trailing pulses in the Crab repeated in the X-ray and {gamma}-ray regions, presence of profile peaks at lower energies aligned with {gamma}-ray peaks-all point to the inverse Compton origin of the high-energy emission from majority of pulsars.

Lyutikov, Maxim [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States)

2012-09-20

382

Compton scattering study and electronic structure of different phases of NH4NO3  

NASA Astrophysics Data System (ADS)

In this paper, we present energy bands, density of states and the nature of hydrogen bonding in different temperature-dependent phases of NH4NO3, namely phases II (357-398 K), III (305-357 K) and IV (257-305 K), using the full potential linearized augmented plane wave and linear combination of atomic orbitals (LCAO) methods. Both band structure calculations show the insulating character of the II-IV phases of NH4NO3. In addition, we have reported the isotropic Compton profile of NH4NO3(IV) measured using 661.65 keV ?-radiation from a 137Cs isotope. The experimental momentum density has been compared with that based on density functional theory (DFT) and Hartree-Fock schemes within the LCAO method. It is seen that the LCAO with hybridization of DFT and Hartree-Fock (so-called B3LYP) gives better agreement with the present Compton profile measurement.

Jain, Pradeep; Sahariya, Jagrati; Ahuja, B. L.

2013-06-01

383

Compton scattering off polarized electrons with a High Finesse Fabry-Pérot cavity at JLab  

Microsoft Academic Search

We built and commissioned a new type of Compton polarimeter to measure the electron beam polarization at the Thomas Jefferson National Accelerator Facility (Virginia, USA). The heart of this polarimeter is a high-finesse monolithic Fabry-Perot cavity. Its purpose is to amplify a primary 300 mW laser beam in order to improve the signal to noise ratio of the polarimeter. It

Nicholas Falletto; M. Authier; G. Bardin; Maud Baylac; M. Boyer; F. Bugeon; Etienne Burtin; C Calvata; N. Colombel; G. Congretel; R. Coquillard; G. Coulloux; B. Couzy; P. Deck; A. Delbart; D. Desforges; A. Donati; B. Duboue; Stephanie Escoffier; F. Farci; Bernard Frois; P. Girardot; J. Guillotau; C. Henriot; J. Jardillier; C. Jeanney; M. Juillard; J. P. Jorda; P. Legou; David Lhuillier; Y. Lussignol; Philippe Mangeot; X. Martin; F. Marie; Jacques Martino; F Maurier; B. Mazeau; J. F. Millot; F. Molinie; J. P. Mols; J. P. Mouly; M. Mur; Damian Neyret; T. Pedrol; Stephane Platchkov; G. Pontet; Thierry Pussieux; Y. Queinec; P C Rebourgeard; J. C. Sellier; Gérard Tarte; C. Veyssiere; A. Zakharian; Pierre Bertin; Joseph Mitchell; J. M. Mackowski; L. Pinard

2000-01-01

384

Measurement of Deeply Virtual Compton Scattering (DVCS) cross sections with CLAS  

SciTech Connect

Extraction of DVCS unpolarized and polarized cross sections in the largest kinematic domain ever explored in the valence region. Results are in good agreement with GPD model (VGG) predictions. Extraction of Compton Form Factors (M. Guidal) by fitting simultaneously these unpolarizedand polarized cross sections gives a large set of results in a very large kinematic domain for Re(H ) and Im(H ). Analysis of the data from the second part of the e1-DVCS experiment underway.

Hyon-Suk Jo

2012-04-01

385

Limits on Light-Speed Anisotropies from Compton Scattering of High-Energy Electrons  

Microsoft Academic Search

The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the

J.-P. Bocquet; A. Lleres; C. Perrin; D. Rebreyend; D. Moricciani; L. Casano; R. Di Salvo; V. Bellini; A. Giusa; F. Mammoliti; C. Randieri; G. Russo; M. L. Sperduto; M. C. Sutera; M. Beretta; P. Levi Sandri; A. DAngelo; A. Fantini; D. Franco; R. Messi

2010-01-01

386

Compton scattering off polarized electrons with a high-finesse Fabry–Pérot Cavity at JLab  

Microsoft Academic Search

We built and commissioned a new type of Compton polarimeter to measure the electron beam polarization at the Thomas Jefferson National Accelerator Facility (Virginia, USA). The heart of this polarimeter is a high-finesse monolithic Fabry–Pérot cavity. Its purpose is to amplify a primary 300 mW laser beam in order to improve the signal to noise ratio of the polarimeter. It

N. Falletto; M. Authier; M. Baylac; M. Boyer; F. Bugeon; E. Burtin; C. Cavata; N. Colombel; G. Congretel; R. Coquillard; G. Coulloux; B. Couzy; P. Deck; A. Delbart; D. Desforges; A. Donati; B. Duboué; S. Escoffier; F. Farci; B. Frois; P. Girardot; J. Guillotau; C. Henriot; C. Jeanney; M. Juillard; J.-P Jorda; P. Legou; D. Lhuillier; Y. Lussignol; P. Mangeot; X. Martin; F. Marie; J. Martino; M. Maurier; B. Mazeau; J. F Millot; F. Molinié; J.-P. Mouly; M. Mur; D. Neyret; T. Pédrol; S. Platchkov; G. Pontet; T. Pussieux; Y. Queinec; P. Rebourgeard; J. C Sellier; G. Tarte; C. Veyssière; A. Zakarian; P. Bertin; A. Cosquer; J. P Chen; J. Mitchell; J.-M Mackowski; L. Pinard

2001-01-01

387

XENA: a liquid-xenon Compton telescope for gamma-ray astrophysics in the MeV regime  

NASA Astrophysics Data System (ADS)

XENA is a new Compton telescope concept, designed to image about 50% of the gamma-ray sky with a sensitivity that would significantly surpass CGRO/COMPTEL's multi-year sensitivity with a 2 weeks balloon flight from the Southern Hemisphere. The detector, based on liquid xenon time-projection chambers, is optimized for approximately 0.3 - 10 MeV and combines high efficiency within a 3 sr field-of-view with approximately 1 degree(s) angular resolution and excellent background reduction capability. XENA's primary scientific goal is the discovery and mapping of (superscript 60)Fe radioactivity from the Galaxy, which is pivotal for understanding nucleosynthesis. XENA will detect (superscript 60)Fe even if current predictions are 7X overestimated. At 1.8 MeV, XENA's sensitivity (6 10(superscript -6) cm(superscript -2) s(superscript -1)) will significantly refine the COMPTEL (superscript 26)Al mapping along the Southern Milky Way. Also, XENA would be the first instrument capable to decide whether the 3 - 7 MeV excess seen in Orion is indeed due to nuclear lines from (superscript 12)C and (superscript 16)O, and it could discover the predicted lower-energy lines. The scanned sky area includes many continuum (gamma) -ray sources as well, such as pulsars and numerous (gamma) -ray AGNs. Secondary scientific objectives include also supernova remnants, gamma-ray bursts, and solar flares.

Aprile, Elena; Egorov, Valeri; Giboni, Karl-Ludwig; Kahn, Steven M.; Kozu, Tomotake; Oberlack, Uwe G.; Centro, S.; Ventura, S.; Doke, Tadayoshi; Kikuchi, Jun; Chupp, Edward L.; Dunphy, Philip P.; Hartmann, Dieter H.; Leising, Mark D.; Bloemen, H.

1998-07-01

388

X-ray pulse generation via laser Compton scattering using quasi-monoenergetic electron beam driven by laser acceleration  

NASA Astrophysics Data System (ADS)

We have demonstrated X-ray generation via laser Compton scattering using a laser-accelerated quasi-monoenergetic electron beam. X-rays were generated by scattering a femtosecond laser pulse (800 nm, 140 mJ, 100 fs) off a quasi-monoenergetic electron beam containing 70 pC electrons in the monoenergetic peak with an energy of 60 MeV produced by focusing an intense laser pulse (800 nm, 700 mJ, 40 fs) on a helium gas jet. A well-collimated X-ray beam with a divergence angle of approximately 5 mrad was generated. The number of X-ray photons was estimated to be 2x10^7 per pulse. The characteristics of X-rays were also investigated using simulation. The spectrum of X-rays emitted within the scattered angle of 5 mrad had a quasi-monochromatic structure with a peak at 60 keV. The number of X-ray photons was 1.8 x10^7, which was in a good agreement with the experimental result. The allowance delay range between the two laser pulses for X-ray generation was approximately 100 fs, and was nearly equal to the duration of the laser pulse scattered by the electron pulse. This suggests that the X-ray pulse duration was shorter than 100 fs.

Miura, Eisuke; Kuroda, Ryunosuke; Toyokawa, Hiroyuki

2012-10-01

389

A GAMMA-SCATTERING SOIL DENSITY GAUGE FOR SUBSURFACE MEASUREMENTS  

Microsoft Academic Search

A gage for in situ measurements of soil densities with an accuracy of ; about l per cent which can be used at depths down to 1000 ft is described. A ; caesium-137 gamma -ray source is separated by a cylindrical lead shield from a ; Geiger counter which detects the gamma -radiation scattered by the soil. The ; optimum

J. F. Cameron; M. S. Bourne

1958-01-01

390

Design and optimization of a highly efficient optical multipass system for ?-ray beam production from electron laser beam Compton scattering  

NASA Astrophysics Data System (ADS)

A new kind of nonresonant optical recirculator, dedicated to the production of ? rays by means of Compton backscattering, is described. This novel instrument, inspired by optical multipass systems, has its design focused on high flux and very small spectral bandwidth of the ?-ray beam. It has been developed to fulfill the project specifications of the European Extreme Light Infrastructure "Nuclear Pillar," i.e., the Gamma Beam System. Our system allows a single high power laser pulse to recirculate 32 times synchronized on the radio frequency driving accelerating cavities for the electron beam. Namely, the polarization of the laser beam and crossing angle between laser and electrons are preserved all along the 32 passes. Moreover, optical aberrations are kept at a negligible level. The general tools developed for designing, optimizing, and aligning the system are described. A detailed simulation demonstrates the high efficiency of the device.

Dupraz, K.; Cassou, K.; Delerue, N.; Fichot, P.; Martens, A.; Stocchi, A.; Variola, A.; Zomer, F.; Courjaud, A.; Mottay, E.; Druon, F.; Gatti, G.; Ghigo, A.; Hovsepian, T.; Riou, J. Y.; Wang, F.; Mueller, A. C.; Palumbo, L.; Serafini, L.; Tomassini, P.

2014-03-01

391

Compton profile of polycrystalline tungsten  

SciTech Connect

In this paper we report the experimental Compton profile of polycrystalline tungsten. The measurements have been made by scattering 59.54-keV ..gamma.. rays and are compared with the band-structure calculation of Papanicolaou et al. These results have also been compared with our calculation based on the renormalized-free-atom model with different 5d-6s configurations. Best agreement with experiment is found for the 5d/sup 5.4/6s/sup 0.6/ electron configuration.

Mittal, U.; Sharma, B.K.; Mohammad, F.M.; Ahuja, B.L.

1988-12-15

392

High-Energy gamma-Ray BEAMS from Compton-Backscattered Laser Light.  

National Technical Information Service (NTIS)

Collisions of light photons with relativistic electrons have previously been used to produce polarized gamma -ray beams with modest (-10%) resolution but relatively low intensity. In contrast, the LEGS project (Laser + Electron Gamma Source) at Brookhaven...

A. M. Sandorfi, M. J. LeVine, C. E. Thorn, G. Giordano, G. Matone

1983-01-01

393

Deeply virtual Compton scattering to the twist-four accuracy: Impact of finite-t and target mass corrections  

NASA Astrophysics Data System (ADS)

We carry out the first complete calculation of kinematic power corrections ˜t/Q2 and ˜m2/Q2 to several key observables in deeply virtual Compton scattering. The issue of convention dependence of the leading twist approximation is discussed in detail. In addition, we work out representations for the higher twist corrections in terms of double distributions, Mellin-Barnes integrals and also within a dissipative framework. This study removes an important source of uncertainties in the QCD predictions for intermediate photon virtualities Q2˜1-5 GeV2 that are accessible in the existing and planned experiments. In particular the finite-t corrections are significant and must be taken into account in the data analysis.

Braun, V. M.; Manashov, A. N.; Müller, D.; Pirnay, B. M.

2014-04-01

394

Diagnostics for the optimization of an 11 keV inverse Compton scattering x-ray source  

NASA Astrophysics Data System (ADS)

In a scope of a collaboration between Thales Communications & Security and CEA DAM DIF, 11 keV Xrays were produced by inverse Compton scattering on the ELSA facility. In this type of experiment, X-ray observation lies in the use of accurate electron and laser beam interaction diagnostics and on fitted X-ray detectors. The low interaction probability between < 100 ?m width, 12 ps [rms] length electron and photon pulses requires careful optimization of pulse spatial and temporal covering. Another issue was to observe 11 keV X-rays in the ambient radioactive noise of the linear accelerator. For that, we use a very sensitive detection scheme based on radio luminescent screens.

Chauchat, A.-S.; Brasile, J.-P.; Le Flanchec, V.; Nègre, J.-P.; Binet, A.; Ortega, J.-M.

2013-04-01

395

Microscopic magnetic properties of an oxygen-doped Tb-Fe thin film by magnetic Compton scattering  

NASA Astrophysics Data System (ADS)

The magnetic Compton scattering of a Tb32Fe55O13 film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect the magnetization process of the magnetic moments of Tb and Fe.

Agui, Akane; Unno, Tomoya; Matsumoto, Sayaka; Suzuki, Kousuke; Koizumi, Akihisa; Sakurai, Hiroshi

2013-11-01

396

Beam Measurement of 11.424 GHz X-Band Linac for Compton Scattering X-ray Source  

SciTech Connect

An inverse Compton scattering X-ray source for medical applications, consisting of an X-band (11.424 GHz) linac and Q-switched Nd:YAG laser, is currently being developed at the University of Tokyo. This system uses an X-band 3.5-cell thermionic cathode RF gun for electron beam generation. We can obtain a multi-bunch electron beam with this gun. The beam is accelerated to 30 MeV by a traveling-wave accelerating tube. So far, we have verified stable beam generation (around 2.3 MeV) by using the newly designed RF gun and we have succeeded in beam transportation to a beam dump.

Natsui, Takuya; Mori, Azusa; Masuda, Hirotoshi; Uesaka, Mitsuru [Nuclear Professional School, School of Engineering, University of Tokyo, 22-2 Shirane-shirakata, Tokai, Naka, Ibaraki 319-1188 (Japan); Sakamoto, Fumito [Akita National College of Technology, 1-1 Iijima-bunkyo, Akita city, Akita 011-8511 (Japan)

2010-11-04

397

Diagnostics for the optimization of an 11 keV inverse Compton scattering x-ray source  

SciTech Connect

In a scope of a collaboration between Thales Communications and Security and CEA DAM DIF, 11 keV Xrays were produced by inverse Compton scattering on the ELSA facility. In this type of experiment, X-ray observation lies in the use of accurate electron and laser beam interaction diagnostics and on fitted X-ray detectors. The low interaction probability between < 100 {mu}m width, 12 ps [rms] length electron and photon pulses requires careful optimization of pulse spatial and temporal covering. Another issue was to observe 11 keV X-rays in the ambient radioactive noise of the linear accelerator. For that, we use a very sensitive detection scheme based on radio luminescent screens.

Chauchat, A.-S.; Brasile, J.-P [Thales Communications and Security, 4 avenue des Louvresses 92230 Gennevilliers (France); Le Flanchec, V.; Negre, J.-P.; Binet, A. [CEA DAM DIF, Bruyeres-le-Chatel 91290 Arpajon (France); Ortega, J.-M. [LCP Universite Paris-Sud, Bat. 201, 91405 Orsay (France)

2013-04-19

398

Nondestructive Detection of Heavily Shielded Materials by Using Nuclear Resonance Fluorescence with a Laser-Compton Scattering ?-ray Source  

NASA Astrophysics Data System (ADS)

We perform a proof-of-principle experiment for a nondestructive method for detecting the elemental and isotopic composition of materials concealed by heavy shields such as iron plates with a thickness of several centimeters. This method uses nuclear resonance fluorescence (NRF) triggered by an energy-tunable laser-Compton scattering (LCS) ?-ray source. One-dimensional mapping of a lead block hidden behind 1.5-cm-thick iron plates is obtained by measuring an NRF ?-ray of a lead isotope 208Pb. We observe a 5512-keV ?-ray from 208Pb excited by the quasi-monochromatic LCS ?-rays with energies up to 5.7 MeV. The edge position of the lead block is consistent with the exact position within the uncertainty.

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Nishimori, Nobuyuki; Minehara, Eisuke; Hayakawa, Takehito; Shizuma, Toshiyuki; Toyokawa, Hiroyuki; Ohgaki, Hideaki

2009-03-01

399

Rayleigh and Compton scattering cross sections for low, medium and high Z elements in the energy region 23.18 <= E <= 30.85 keV  

Microsoft Academic Search

Using nearly monoenergetic unpolarised Kalpha x-ray photons coherent (Rayleigh) and incoherent (atomic Compton) scattering cross sections in the atomic region 13 <= Z <= 82 have been measured at 23.18, 24.14, 25.19, 26.27 and 30.85 keV. Experimental scattering cross sections in the momentum transfer region 1.322 h Å-1 <= q <= 1.759 h Å-1 [q = sin (theta\\/2)lambda(Å)] were obtained

D. V. Rao; R. Cesareo; G. E. Gigante

1996-01-01

400

X-ray generation via laser Compton scattering using quasi-monoenergetic electron beam driven by laser-plasma acceleration  

NASA Astrophysics Data System (ADS)

The first demonstration of X-rays generated via laser Compton scattering using a quasi-monoenergetic electron beam with a narrow energy spread driven by laser-plasma acceleration is reported. X-rays are produced by scattering a femtosecond laser pulse (800 nm, 140 mJ, 100 fs) off a quasi-monoenergetic electron beam containing 70 pC electrons in the monoenergetic peak with an energy of 60 MeV produced by focusing an intense laser pulse (800 nm, 700 mJ, 40 fs) on a helium gas jet. A well-collimated X-ray beam with a divergence angle of approximately 5 mrad is produced. The number of X-ray photons is estimated to be 2×107 per pulse. Numerical simulation results show that the spectrum of the X-rays within the scattered angle of 5 mrad is the quasi-monochromatic distribution with a peak at 60 keV, and the photon number is 1.8×107. The X-ray photon number is in a good agreement with the experimental result.

Miura, Eisuke; Ishii, Satoshi; Tanaka, Kenji; Kashiwaya, Shun; Kuroda, Ryunosuke; Toyokawa, Hiroyuki

2012-12-01

401

Advanced Compton Camera with the ability in electron tracking based on Micro Pixel Gas Detector for Medical Imaging  

Microsoft Academic Search

We have developed the electron tracking Compton camera (ETCC) with reconstructing the 3-D tracks of the scattered electron in Compton process in the range from sub-MeV to several MeV for both gamma-ray astronomy and medical imaging [Bhattacharya, D, et al., 2004; Kanbach, G, et al., 2004]. By measuring both the directions and energies of a recoil gamma ray and a

Toru Tanimori; Kaori Hattori; Shigeto Kabuki; Hidekazu Kawashima; Hiroyuki Kimura; Ryota Kohara; E. Kunieda; A. Kubo; H. Kubo; O. Miyazaki; K. Miuchi; T. Nakahara; T. Nakazawa; H. Nishimura; K. Ogawa; Y. Okada; R. Orito; H. Saji; H. Sekiya; T. Shirahata; A. Takada; M. Ueda; K. Ueno; E. Yamamoto

2006-01-01

402

Analytical image reconstruction of cone-beam projections from limited-angle Compton camera data  

Microsoft Academic Search

Since the integration of gamma-rays on a cone is measured with Compton cameras, some sort of image reconstruction method is necessary. Parra (2000) developed an analytical reconstruction algorithm based on a spherical harmonics expansion of projection data that covers the entire scattering-angle range. The measurable scattering angle range is limited due to the electrical noise of the detector and to

Takehiro Tomitani; Masahiko Hirasawa

2003-01-01

403

Few arc-minute and keV resolutions with the TIGRE Compton telescope  

NASA Technical Reports Server (NTRS)

The tracking and imaging gamma ray experiment (TIGRE) Compton telescope concept can provide an angular resolution of a few arcmin, an energy resolution of a few keV and high sensitivity, while providing the wide field of view necessary for surveying and monitoring observations. Silicon and CdZnTe strip detectors are used to detect Compton pair events and determine their incident directions and energies. Above 400 keV, Compton recoil electrons are tracked through successive layers of thin silicon strip detectors. Compton scattered photons are detected with CdZnTe strip detectors. Pair electrons and positrons are tracked to provide high sensitivity observations in the 10 to 100 MeV range. Polarization studies are performed with large angle Compton scatter events. The TIGRE concept and development status are described.

Zych, A.; Bhattacharya, D.; Dixon, D.; ONeill, T.; Tuemer, T.; White, R. S.; Ryan, J.; McConnell, M.; Macri, J.; Oegelman, H.; Paulos, R.; Wheaton, W.; Akyuez, A.; Samimi, J.; Oezel, M.

1997-01-01

404

Limits on light-speed anisotropies from Compton scattering of high-energy electrons.  

PubMed

The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility's GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the two-sided limit of 1.6×10(-14) at 95% confidence level on a combination of the parity-violating photon and electron coefficients (?(o+))(YZ), (?(o+))(ZX), c(TX), and c(TY). This new constraint provides an improvement over previous bounds by 1 order of magnitude. PMID:20867292

Bocquet, J-P; Moricciani, D; Bellini, V; Beretta, M; Casano, L; D'Angelo, A; Di Salvo, R; Fantini, A; Franco, D; Gervino, G; Ghio, F; Giardina, G; Girolami, B; Giusa, A; Gurzadyan, V G; Kashin, A; Knyazyan, S; Lapik, A; Lehnert, R; Levi Sandri, P; Lleres, A; Mammoliti, F; Mandaglio, G; Manganaro, M; Margarian, A; Mehrabyan, S; Messi, R; Nedorezov, V; Perrin, C; Randieri, C; Rebreyend, D; Rudnev, N; Russo, G; Schaerf, C; Sperduto, M L; Sutera, M C; Turinge, A; Vegna, V

2010-06-18

405

Limits on Light-Speed Anisotropies from Compton Scattering of High-Energy Electrons  

NASA Astrophysics Data System (ADS)

The possibility of anisotropies in the speed of light relative to the limiting speed of electrons is considered. The absence of sidereal variations in the energy of Compton-edge photons at the European Synchrotron Radiation Facility’s GRAAL facility constrains such anisotropies representing the first nonthreshold collision-kinematics study of Lorentz violation. When interpreted within the minimal standard-model extension, this result yields the two-sided limit of 1.6×10-14 at 95% confidence level on a combination of the parity-violating photon and electron coefficients (?˜o+)YZ, (?˜o+)ZX, cTX, and cTY. This new constraint provides an improvement over previous bounds by 1 order of magnitude.

Bocquet, J.-P.; Moricciani, D.; Bellini, V.; Beretta, M.; Casano, L.; D'Angelo, A.; di Salvo, R.; Fantini, A.; Franco, D.; Gervino, G.; Ghio, F.; Giardina, G.; Girolami, B.; Giusa, A.; Gurzadyan, V. G.; Kashin, A.; Knyazyan, S.; Lapik, A.; Lehnert, R.; Levi Sandri, P.; Lleres, A.; Mammoliti, F.; Mandaglio, G.; Manganaro, M.; Margarian, A.; Mehrabyan, S.; Messi, R.; Nedorezov, V.; Perrin, C.; Randieri, C.; Rebreyend, D.; Rudnev, N.; Russo, G.; Schaerf, C.; Sperduto, M. L.; Sutera, M. C.; Turinge, A.; Vegna, V.

2010-06-01

406

Injector Study for Compact Hard X-Ray Source via Laser Compton Scattering  

NASA Astrophysics Data System (ADS)

Compact hard X-ray source via laser Compton sattering has been developed in SHI and AIST. Our system has the injector and the linac and the high power laser system. The injector has a photo-cathode rf gun with a solenoid magnet. To enhance the X-ray yeild, we are planning to increase electron beam charge up to 5 nC/bunch and to make multi-bunch beam. The beam tracking simulation in the injector have been performed by changing laser spot size, laser pulse width, rf phase and solenoid field to optimize the distance between the injector and the linac for 5 nC/bunch high charge beam. In addition, high charge multi-bunch beam simulation in rf-gun cavity have been carried out to investigate the influence by the beam loading and the wake field.

Kuroda, Ryunosuke; Toyokawa, Hiroyuki; Sei, Norihiro; Yasumoto, Masato; Ogawa, Hiroshi; Koike, Masaki; Yamada, Kawakatsu; Nakajyo, Terunobu; Sakai, Fumio; Yanagida, Tatsuya

407

High-energy gamma-ray beams from Compton-backscattered laser light  

SciTech Connect

Collisions of light photons with relativistic electrons have previously been used to produce polarized ..gamma..-ray beams with modest (-10%) resolution but relatively low intensity. In contrast, the LEGS project (Laser + Electron Gamma Source) at Brookhaven will produce a very high flux (>2 x 10/sup 7/ s/sup -1/) of background-free polarized ..gamma.. rays whose energy will be determined to a high accuracy (..delta..E = 2.3 MeV). Initially, 300(420)-MeV ..gamma.. rays will be produced by backscattering uv light from the new 2.5(3.0)-GeV X-ray storage ring of the National Synchrotron Light Source (NSLS). The LEGS facility will operate as one of many passive users of the NSLS. In a later stage of the project, a Free Electron Laser is expectred to extend the ..gamma..-ray energy up to 700 MeV.

Sandorfi, A.M.; LeVine, M.J.; Thorn, C.E.; Giordano, G.; Matone, G.

1983-01-01

408

Compton Profile Study of Intermetallic Ti{sub 3}Al  

SciTech Connect

The Compton scattering measurement on intermetallic alloy Ti{sub 3}Al is reported in this work. The measurement is made using 59.54 keV gamma-rays from Am{sup 241} source. Theoretical calculation of Compton profile is also performed employing CRYSTAL code within the framework of density functional theory to compare with the measurement. The theoretical profile of the alloy is also synthesized following the superposition model taking the published Compton profiles of elemental solids from the APW method. The experimental study of charge transfer in the alloys has also been done by performing the experimental Compton profile measurements on Ti and Al following the superposition model and charge transfer from Al to Ti is clearly seen on the alloy formation.

Vyas, V.; Sharma, G. [Department of Physics, Banasthali University, Banasthali-304022 (India); Mishra, M. C.; Sharma, B. K. [Department of Physics, University of Rajasthan, Jaipur-302004 (India); Joshi, K. B. [Department of Physics, University College of Science, M.L.Sukhadia University, Udaipur-