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1

Inverse compton scattering gamma ray source  

NASA Astrophysics Data System (ADS)

Special Nuclear Materials (SNM) (e.g. U-235, Pu-239) can be detected by active interrogation with gamma rays (>6 MeV) through photofission. For long-range detection (˜1 km), an intense beam of gamma rays (˜1014 per second) is required in order to produce measurable number of neutrons. The production of such fluxes of gamma rays, and in the pulse formats useful for detection, presents many technical challenges, and requires novel approaches to the accelerator and laser technology. RadiaBeam is currently designing a gamma ray source based on Inverse Compton Scattering (ICS) from a high-energy electron beam. To achieve this, improvements in photoinjector, linac, final focus, and laser system are planned. These enhanced sub-systems build on parallel work being performed at RadiaBeam, UCLA, and elsewhere. A high-repetition rate photoinjector, a high-gradient S-band linac, and a laser pulse recirculator will be used. The proposed system will be a transportable source of high-flux, high-energy quasi-monochromatic gamma rays for active interrogation of special nuclear materials.

Boucher, S.; Frigola, P.; Murokh, A.; Ruelas, M.; Jovanovic, I.; Rosenzweig, J. B.; Travish, G.

2009-09-01

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

Bursts of gamma rays from Compton scattering at cosmological distances  

Microsoft Academic Search

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

Andrzej A. Zdziarski; Roland Svensson; Bohdan Paczynski

1991-01-01

4

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Astrophysics Data System (ADS)

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.

1995-05-01

5

COMPACT, TUNABLE COMPTON SCATTERING GAMMA-RAY SOURCES  

SciTech Connect

Recent progress in accelerator physics and laser technology have enabled the development of a new class of gamma-ray light sources based on Compton scattering between a high-brightness, relativistic electron beam and a high intensity laser pulse produced via chirped-pulse amplification (CPA). 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 {gamma}-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, F V; Albert, F; Anderson, G G; Anderson, S G; Bayramian, A J; Betts, S M; Chu, T S; Cross, R R; Ebbers, C A; Fisher, S E; Gibson, D J; Ladran, A S; Marsh, R A; Messerly, M J; O'Neill, K L; Semenov, V A; Shverdin, M Y; Siders, C W; McNabb, D P; Barty, C J; Vlieks, A E; Jongewaard, E N; Tantawi, S G; Raubenheimer, T O

2009-08-20

6

Self-scattering in gamma ray sources used in compton scattering experiments  

NASA Astrophysics Data System (ADS)

The energy degradation of various monochromatic gamma ray sources due to self-scattering has been studied by Monte Carlo simulation techniques. A direct measurement of the energy spectrum of the 198Au source used for Compton scattering experiments at the Hahn-Meitner Institute (HMI) confirms the predictions of the emission of a low energy tail. The effect of the tail on Compton profiles is examined and a method of correction is proposed and applied to measurements made at the HMI.

Rollason, A. J.; Felsteiner, J.; Bauer, G. E. W.; Schneider, J. R.

1987-05-01

7

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

SciTech Connect

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 [Kansai Photon Science Institute, Japan Atomic Energy Agency, Kizu, Kyoto 619-0215 (Japan); National Astronomical Observatory, Osawa, Mitaka, Tokyo 181-8588 (Japan); Hajima, Ryoichi [Quantum Beam Science Directorate, Japan Atomic Energy Agency, Tokai, Ibaraki 319-1195 (Japan)

2008-06-24

8

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

9

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

10

Resonant Compton scattering in models of gamma-ray burst sources: 2, Numerical modeling  

SciTech Connect

We numerically calculate photon spectra produced from the resonant Compton scattering of blackbody photons by a beam of relativistic electrons and positrons. The beam is assumed to be directed radially outward along the magnetic axis of a highly magnetized neutron star. We assume a dipole magnetic field geometry, and include the effects of magnetic Compton-scattering energy losses on the particles in the beam during transport. A range of surface blackbody radiation temperatures near 1 keV and magnetic field strengths near 2 {times} 10{sup 12} Gauss are studied for power-law electron and positron source functions. If the beam is injected with a power law distribution with energy distribution index {Gamma} and low-energy cutoff {gamma}{sub {asterisk}}, then the calculated Compton-scattered photon spectra are similar to observed gamma-ray burst spectra, with a spectral index {alpha} which breaks from {alpha} {congruent} 1 to {alpha} {congruent} {Gamma}. 10 refs., 4 figs.

Vitello, P. (Lawrence Livermore National Lab., CA (USA). Physics Dept.); Dermer, C.D. (Lawrence Livermore National Lab., CA (USA). Physics Dept. California Univ., Berkeley, CA (USA). Space Sciences Lab.)

1990-01-01

11

Gamma-gamma density and lithology tools simulation based on GEANT4 advanced low energy Compton scattering (GALECS) package  

NASA Astrophysics Data System (ADS)

Geophysical bore-hole data represent the physical properties of rocks, such as density and formation lithology, as a function of depth in a well. Properties of rocks are obtained from gamma ray transport logs. Transport of gamma rays, from a 137Cs point gamma source situated in a bore-hole tool, through rock media to detectors, has been simulated using a GEANT4 radiation transport code. The advanced Compton scattering concepts were used to gain better analyses about well formation. The simulation and understanding of advanced Compton scattering highly depends on how accurately the effects of Doppler broadening and Rayleigh scattering are taken into account. A Monte Carlo package that simulates the gamma-gamma well logging tools based on GEANT4 advanced low energy Compton scattering (GALECS).

Esmaeili-Sani, Vahid; Moussavi-Zarandi, Ali; Boghrati, Behzad; Afarideh, Hossein

2012-02-01

12

Resonant Compton scattering in models of gamma-ray burst sources: 1, Theory  

SciTech Connect

We give a simplified treatment of the physics involved when soft photons are Compton-scattered by relativistic electrons beamed along the direction of a strong magnetic field. The following results are obtained through elementary considerations: If the steady-state electron distribution function is described by a power-law spectrum with index p, then the spectral index {alpha} of the Compton-scattered photon number spectrum breaks from {alpha} {congruent} 0 to {alpha} {congruent} p + 2 at the dimensionless scattered photon energy {epsilon}{sub s} {equivalent to} hv{sub s}/m{sub e}c{sup 2} {approx} 2{epsilon}{sub B}{sup 2}/{epsilon}, where {epsilon}{sub B} and {epsilon} are the dimensionless cyclotron and soft photon energies, respectively; the characteristic beaming angle {theta}{sub s} of photons scattered to high energies goes roughly as {theta}{sub s} {approximately} {epsilon}{sub B}/{epsilon}{sub s}; if electrons have Lorentz factor {gamma} {approx gt} {epsilon}{sub B}/{epsilon}, then the resonant Compton-scattering electron energy-loss rate {vert bar}{dot {gamma}}{vert bar} {proportional to} {gamma}{sup {minus}1}; the scattered photon spectrum produced when monoenergetic electrons cool by scattering soft photons has spectral index {alpha} {congruent} 1; if electrons are injected in the shape of power law with injection spectral index {Gamma}, then the resonant-scattered cooling spectrum has spectral index {alpha} {congruent} {Gamma}. Resonant Compton-scattered photon spectra, similar to observed gamma-ray burst spectra, result from the injection of a power-law distribution of electrons with a low-energy cutoff into a thick target of soft photons. This model can satisfy the x-ray paucity constraint, as well constraints imposed by {gamma}-B and {gamma}-{gamma} photon attenuation for MeV photons produced very close to the surface of neutron stars with teragauss fields at kiloparsec distances.

Dermer, C.D. (California Univ., Berkeley, CA (USA). Space Sciences Lab. Lawrence Livermore National Lab., CA (USA). Physics Dept.); Vitello, P. (Lawrence Livermore National Lab., CA (USA). Physics Dept.)

1990-01-01

13

First Measurement of pi e -> pi e gamma Pion Virtual Compton Scattering  

Microsoft Academic Search

Pion Virtual Compton Scattering (VCS) via the reaction pi e --> pi e gamma\\u000awas observed in the Fermilab E781 SELEX experiment. SELEX used a 600 GeV\\/c pi-\\u000abeam incident on target atomic electrons, detecting the incident pi- and the\\u000afinal state pi-, electron and gamma. Theoretical predictions based on chiral\\u000aperturbation theory are incorporated into a Monte Carlo simulation

G. Alkhazov; A. G. Atamantchouk; M. Y. Balatz; N. F. Bondar; P. S. Cooper; L. J. Dauwe; G. V. Davidenko; U. Dersch; A. G. Dolgolenko; G. B. Dzyubenko; R. Edelstein; L. Emediato; A. M. F. Endler; J. Engelfried; I. Eschrich; C. O. Escobar; A. V. Evdokimov; F. G. Garcia; M. Gaspero; I. Giller; V. L. Golovtsov; P. Gouffon; E. Gulmez; M. Iori; S. Y. Jun; M. Kaya; J. Kilmer; V. T. Kim; L. M. Kochenda; I. Konorov; A. P. Kozhevnikov; A. G. Krivshich; H. Kruger; M. A. Kubantsev; V. P. Kubarovsky; A. I. Kulyavtsev; N. P. Kuropatkin; V. F. Kurshetsov; A. Kushnirenko; S. Kwan; J. Lach; A. Lamberto; L. G. Landsberg; I. Larin; E. M. Leikin; M. Luksys; T. Lungov; V. P. Maleev; D. Mao; Mao Chensheng; Mao Zhenlin; P. Mathew; M. Mattson; V. Matveev; E. McCliment; M. A. Moinester; V. V. Molchanov; A. Morelos; K. D. Nelson; A. V. Nemitkin; P. V. Neoustroev; C. Newsom; A. P. Nilov; S. B. Nurushev; Y. Onel; E. Ozel; S. Ozkorucuklu; A. Penzo; S. I. Petrenko; P. Pogodin; M. Procario; V. A. Prutskoi; E. Ramberg; G. F. Rappazzo; B. V. Razmyslovich; V. I. Rud; J. Russ; P. Schiavon; J. Simon; A. I. Sitnikov; D. Skow; V. J. Smith; M. Srivastava; V. Steiner; V. Stepanov; L. Stutte; M. Svoiski; N. K. Terentyev; G. P. Thomas; L. N. Uvarov; A. N. Vasiliev; D. V. Vavilov; V. S. Verebryusov; V. A. Victorov; V. E. Vishnyakov; A. A. Vorobyov; K. Vorwalter; J. You; Zhao Wenheng; Zheng Shuchen; R. Zukanovich-Funchal; San Luis; Potos ´ õ

2001-01-01

14

MeV gamma-ray generation from backward Compton scattering at SPring8  

Microsoft Academic Search

A test experimental line at SPring-8 has been constructed for the generation of backward Compton scattered (BCS) gamma-rays by head-on collision between an 8 GeV electron beam and a far-infrared (FIR) laser. For the FIR laser, we use a continuous-wave methanol laser optically pumped by a carbon dioxide (CO2) laser. The FIR laser output power achieved is 1.6 W at

K. Kawase; Y. Arimoto; M. Fujiwara; S. Okajima; M. Shoji; S. Suzuki; K. Tamura; T. Yorita; H. Ohkuma

2008-01-01

15

Pion Compton scattering and bremsstrahlung  

SciTech Connect

The pion polarizability functions are structure functions of pion Compton scattering. They can be assessed in high-energy pion-nucleus bremsstrahlung reactions, {pi}{sup -}+A{yields}{pi}{sup -}+{gamma}+A. We present numerical expectations for pion-nucleus bremsstrahlung cross sections in the Coulomb region, i.e., the small-angle region where the nuclear scattering is dominated by the Coulomb interaction. We investigate the prospects of measuring the polarizability functions for pion-Compton center-of-momentum energies from threshold up to 1 GeV. A meson-exchange model is used for the pion Compton amplitude.

Faeldt, Goeran; Tengblad, Ulla [Department of Physics and Astronomy, Uppsala University, Box 535, S-751 21 Uppsala (Sweden)

2008-07-15

16

Attenuation studies near K-absorption edges using Compton scattered 241 Am gamma rays  

NASA Astrophysics Data System (ADS)

We have carried out photon attenuation measurements at several energies in the range from 49.38 keV to 57.96 keV around the K-absorption edges of the rare earth elements Sm, Eu, Gd, Tb, Dy and Er using 59.54 keV gamma rays from ^{241}Am source after Compton scattering from an aluminium target. Pellets of oxides of the rare earth elements were chosen as mixture absorbers in these investigations. A narrow beam good geometry set-up was used for the attenuation measurements. The scattered gamma rays were detected by an HPGe detector. The results are consistent with theoretical values derived from the XCOM package.

Abdullah, K. K.; Ramachandran, N.; Karunakaran Nair, K.; Babu, B. R. S.; Joseph, Antony; Thomas, Rajive; Varier, K. M.

2008-04-01

17

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

18

Compton scattering polarimeter  

Microsoft Academic Search

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

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

2001-01-01

19

Timelike Compton Scattering  

SciTech Connect

Generalized Parton Distributions (GPDs) have become a key concept in our studies of hadron structure in QCD. The measurement of suitable experimental observables and the extraction of GPDs from these data is one of the high priority 12 GeV programs at Jefferson Lab. Deeply Virtual Compton Scattering (DVCS) is generally thought of as the most promising channel for probing GPDs in the valence quark region. However, the inverse process, Timelike Compton Scattering (TCS) can provide an important complementary measurement, in particular of the real part of the Compton amplitude and power corrections at intermediate values of Q{sup 2}. The first studies of TCS using real tagged and quasi-real untagged photons were performed in Hall B at Jefferson Lab.

Horn, T.; Klein, F. J. [Catholic University of America, Washington, DC 20064 (United States); Illieva, Y. [University of South Carolina, Columbia, SC 29208 (United States); Nadel-Turonski, P.; Stepanyan, S. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Paremuzyan, R. [Yerevan Physics Institute, 375036 Yerevan (Armenia); Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

2011-10-24

20

Nucleon Compton Scattering  

SciTech Connect

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 discussed.

Bogdan Wojtsekhowski

2006-06-04

21

Virtual Compton scattering measurements in the {gamma}*N{yields}{delta} transition  

SciTech Connect

We report on new H(e,e{sup '}p){gamma} measurements in the {delta}(1232) resonance at Q{sup 2}=0.06 (GeV/c){sup 2} carried out simultaneously with H(e,e{sup '}p){pi}{sup 0}. It is the lowest Q{sup 2} for which the virtual Compton scattering (VCS) reaction has been studied in the first resonance region. The VCS measured cross sections are well described by dispersion-relation calculations in which the multipole amplitudes derived from H(e,e{sup '}p){pi}{sup 0} data are used as input, thus confirming the compatibility of the results. The derived resonant magnetic dipole amplitude M{sub 1+}{sup 3/2}=(40.60{+-}0.70{sub stat+sys})(10{sup -3}/m{sub {pi}{sup +}}) at W=1232 MeV is in excellent agreement with the value extracted from H(e,e{sup '}p){pi}{sup 0} measurements.

Sparveris, N. F.; Christopoulou, A.; Karabarbounis, A.; Papanicolas, C. N.; Stiliaris, S. [Institute of Accelerating Systems and Applications and Department of Physics, University of Athens, Athens (Greece); Achenbach, P.; Gayoso, C. Ayerbe; Baumann, D.; Bernauer, J.; Boehm, R.; Ding, M.; Distler, M. O.; Doria, L.; Friedrich, J.; Merkel, H.; Mueller, U.; Neuhausen, R.; Nungesser, L.; Piegsa, A.; Pochodzalla, J. [Institut fur Kernphysik, Universitaet Mainz, Mainz (Germany)] (and others)

2008-07-15

22

Inverse Compton Scattering onto BBR in High Energy Physics and Gamma (MeV-Tev) Astrophysics  

Microsoft Academic Search

We considered the Inverse Compton Scattering (ICS) of charged particles onto\\u000aphotons whose distribution is a Black Body Radiation (BBR) deriving the exact\\u000aenergy and angular differential distribution in the general case and in its\\u000amost useful expansions. These results can be successfully applied in high\\u000aenergy accelerators experiments to evaluate the ICS contribution from the\\u000athermal photons in the

Daniele Fargion; Andrea Salis

1996-01-01

23

Spectral evolution of active galactic nuclei Penrose Compton scattering processes and gamma ray emission from Seyfert galaxies  

NASA Astrophysics Data System (ADS)

In black hole spectral evolution models for active galactic nuclei (AGN), present epoch Seyfert galaxies evolve from an earlier precursor active galaxy (PAG) stage at redshift z is approximately 7 where they acted as the thermal sources responsible for the residual cosmic x ray background (RCXB). The Seyfert galaxies which emerge in this context emit Penrose Compton Scattering (PCS) gamma ray transients on the order of hours with a kinematic cutoff in the spectrum less than or equal to 3 MeV. The EGRET (Energetic Gamma-Ray Experimental Telescope/ OSSE (Oriented Scintillation Spectrometer Experiment/ COMPTEL (Compton Telescope)/ BATSE (Burst and Transient Source Experiment) instruments on the Gamma Ray Observatory (GRO) are appropriate instruments to carry out further tests of this model by studying: PCS gamma ray transient emission from individual galaxies and, the possibility that present epoch PCS gamma ray emitting Seyfert galaxies contribute observable temporal variability to the excess diffuse gamma ray background component less than or equal to 3 MeV.

Leiter, Darryl; Boldt, Elihu

1990-05-01

24

Apparent image formation by Compton-scattered photons in gamma-ray imaging  

Microsoft Academic Search

The solution to the scatter problem remains a major technical challenge in gamma ray imaging. This paper presents a modelization of apparent images formed by scattered photons at various energies. It may be used either to generate a series of realistic multi-energy images or be included in an image enhancement procedure. The application to SPECT is discussed

Mai K. Nguyen; C. Faye; L. Eglin; T. T. Truong

2001-01-01

25

Weak deeply virtual Compton scattering  

Microsoft Academic Search

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

A. V. Radyushkin; A. Psaker

2007-01-01

26

In vivo measurement of the trabecular bone mineral density by coherent and Compton. gamma. -ray scattering  

SciTech Connect

A photon scattering method for measuring the mineral density of trabecular bone (BMD) is described. By computing the ratio of the coherent to Compton scattered photons, the BMD can be measured accurately and without any significant interference by the surrounding tissue. This study shows theoretically and experimentally that an increase in the scatter angle, when using 60 keV photons from Am-241, results in a stronger power dependence on Z. This implies that by increasing the scatter angle, smaller changes in BMD can be detected, thus improving the sensitivity of the measurement. The dependence of the sensitivity on the energy of the incident photons was also investigated. A collimated beam of photons from 1200 mCi of Am-241 (60 keV) was used and the scattered photons were detected at a scatter angle of 71/sup 0/. The system was calibrated by using a new standard which contains bone mineral mixed homogeneously with a marrow simulating substance. This method was applied for the measurement of the calcaneal BMD in 21 normal volunteers and seven paraplegic patients. The BMD values for the normal group ranged from 170-300 mg/cm/sup 3/. The BMD for the paraplegics with injuries older than one year ranged from 90-150 mg/cm/sup 3/. This measurement has potential application in the diagnosis of early osteopenia and in monitoring the effect of various treatment regimens.

Karellas, A.

1984-01-01

27

Portable compton gamma-ray detection system  

DOEpatents

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

28

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

29

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

30

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.

Psaker, A.; Radyushkin, A. V. [Physics Department, Old Dominion University, Norfolk, Virginia 23529 (United States); Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Melnitchouk, W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

2007-03-01

31

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

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

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

34

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

35

The Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

The Arthur Holly Compton Gamma Ray Observatory Compton) is the second in NASA's series of great Observatories. Launched on 1991 April 5, Compton represents a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made. We describe the capabilities of the four scientific instruments, and the observing program of the first 2 years of the mission. Examples of early discoveries by Compton are enumerated, including the discovery that gamma-ray bursts are isotropic but spatially inhomogeneous in their distribution; the discovery of a new class of high-energy extragalacatic gamma-ray sources, the gamma-ray AGNs; the discovery of emission from SN 1987A in the nuclear line of Co-57; and the mapping of emission from Al-26 in the interstellar medium (ISM) near the Galactic center. Future observations will include deep surveys of selected regions of the sky, long-tem studies of individual objects, correlative studies of objects at gamma-ray and other energies, a Galactic plane survey at intermediate gamma-ray energies, and improved statistics on gamma-ray bursts to search for small anisotropies. After completion of the all-sky survey, a Guest Investigator program is in progress with guest observers' time share increasing from 30% upward for the late mission phases.

Gehrels, N.; Chipman, E.; Kniffen, D.

1994-06-01

36

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

37

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?  

Microsoft Academic Search

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

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

1991-01-01

38

Prototype TIGRE Compton gamma-ray balloon-borne telescope  

Microsoft Academic Search

A prototype balloon-borne telescope is being constructed for gamma-ray observations in the MeV energy range. The Tracking and Imaging Gamma-Ray Experiment (TIGRE) uses multi-layers of thin silicon detectors to track and measure the energy losses of Compton recoil electrons. When combined with the direction and energy of the Compton scattered gamma-ray a unique incident direction for each photon event is

D. Bhattacharya; T. J. O'Neill; A. Akyüz; J. Samimi; A. D. Zych

2004-01-01

39

Evaluation of errors due to Compton scattering in gamma-ray emission imaging  

SciTech Connect

A set of computer simulation programs were developed to aid in the design of new instrumentation and in the design and evaluation of algorithms for scatter correction in positron emission computed tomography. 14 references, 15 figures, 3 tables. (ACR)

Bruno, M.F.

1983-12-01

40

Two Compton polarimeter constructions for modern standard gamma-spectroscopy  

Microsoft Academic Search

Two types of Compton polarimeters for gamma-linear polarization measurements are presented. The first one consists of standard Ge-detectors and unites an easy handling and high grade of universality with high polarization sensitivity in the gamma-ray energy range 180-2500 keV. In this device, a low efficiency Ge-crystal scatterer is used with a special diameter-to-length ratio which optimizes the probability for Compton

A. von der Werth; F. Becker; J. Eberth; S. Freund; U. Hermkens; T. Mylaeus; S. Skoda; H. G. Thomas; W. Teichert

1995-01-01

41

CP violation in Compton scattering  

SciTech Connect

I consider Compton scattering off the nucleon in the presence of T violation. I construct the Compton tensor that possesses these features and consider low-energy expansion of the corresponding amplitudes. It allows separation of the Born contribution that depends only on the static properties of the nucleon, such as the electric charge, the mass, the magnetic moment, and the electric dipole moment. I introduce new structure constants, the T-odd nucleon polarizabilities that parametrize the unknown non-Born part. These constants describe the response of the T-violating content of the nucleon to the external quasistatic electromagnetic field. As an estimate, I provide a heavy-baryon ChPT calculation for these new polarizabilities and discuss the implications for the experiment.

Gorchtein, Mikhail [Nuclear Theory Center and Physics Department, Indiana University, Bloomington, Indiana 47403 (United States)

2008-06-15

42

Determination of rest mass energy of the electron by a Compton scattering experiment  

Microsoft Academic Search

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 five scattering angles of

S Prasannakumar; S Krishnaveni; T K Umesh

2012-01-01

43

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

44

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

2007-12-10

45

The Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

The Arthur Holly Compton Gamma Ray Observatory (Compton) was launched by the Space Shuttle Atlantis on 5 April 1991. The spacecraft and instruments are in good health and returning exciting results. The mission provides nearly six orders of magnitude in spectral coverage, from 30 keV to 30 GeV, with sensitivity over the entire range an order of magnitude better than that of previous observations. The 16,000 kilogram observatory contains four instruments on a stabilized platform. The mission began normal operations on 16 May 1991 and is now over half-way through a full-sky survey. The mission duration is expected to be from six to ten years. A Science Support Center has been established at Goddard Space Flight Center for the purpose of supporting a vigorous Guest Investigator Program. New scientific results to date include: (1) the establishment of the isotropy, combined with spatial inhomogeneity, of the distribution of gamma-ray bursts in the sky; (2) the discovery of intense high energy (100 MeV) gamma-ray emission from 3C 279 and other quasars and BL Lac objects, making these the most distant and luminous gamma-ray sources ever detected; (3) one of the first images of a gamma-ray burst; (4) the observation of intense nuclear and position-annihilation gamma-ray lines and neutrons from several large solar flares; and (5) the detection of a third gamma-ray pulsar, plus several other transient and pulsing hard X-ray sources.

Gehrels, N.; Chipman, E.; Kniffen, D. A.

1993-01-01

46

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

SciTech Connect

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 emittance compensated, 11.4 GHz photo-gun and linac to generate 400 pC, 1-2 mm-mrad electron bunches at up to 250 MeV and 120 Hz repetition rate. The effects of jitter in the RF power system are analyzed as well as structure and optic misalignments. Finally, strategies for the mitigation of on-axis Bremsstrahlung noise are discussed.

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

2009-05-07

47

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

48

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

49

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

50

RESONANT COMPTON SCATTERING IN NONTHERMAL ASTROPHYSICAL PLASMAS  

SciTech Connect

The nonthermal effect on the resonant Compton scattering process is investigated in Lorentzian astrophysical plasmas. The screened atomic wave functions and energies for the hydrogenic ion in Lorentzian plasmas are obtained by the Rayleigh-Ritz variational method. The resonance Compton scattering cross section in Lorentzian plasmas is also obtained as a function of the spectral index and plasma parameters by the photon-perturbation Hamiltonian in the dipole representation. It is shown that the nonthermal character of the Lorentzian plasma enhances the resonant Compton scattering cross section. In addition, the nonthermal effect on the cross section is found to be more significant in plasmas with higher densities.

Jung, Young-Dae [Department of Applied Physics, Hanyang University, Ansan, Kyunggi-Do 426-791 (Korea, Republic of)], E-mail: ydjung@hanyang.ac.kr

2009-04-20

51

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

52

Investigating neutron polarizabilities through Compton scattering on 3He.  

PubMed

We examine manifestations of neutron electromagnetic polarizabilities in coherent Compton scattering from the helium-3 nucleus. We calculate gamma3He elastic scattering observables using chiral perturbation theory to next-to-leading order [O(e2Q)]. We find that the unpolarized differential cross section can be used to measure neutron electric and magnetic polarizabilities, while two double-polarization observables are sensitive to different linear combinations of the four neutron spin polarizabilities. PMID:17677903

Choudhury, Deepshikha; Nogga, Andreas; Phillips, Daniel R

2007-06-07

53

The electromagnetic calorimeter in JLab Real Compton Scattering Experiment  

SciTech Connect

A hodoscope calorimeter comprising of 704 lead-glass blocks is described. The calorimeter was constructed for use in the JLab Real Compton Scattering experiment. 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\\%/$\\sqrt{E_\\gamma \\, [GeV]}$, respectively. Design features and performance parameters during the experiment are presented.

Albert Shahinyan; Eugene Chudakov; A. Danagoulian; P. Degtyarenko; K. Egiyan; V. Gorbenko; J. Hines; E. Hovhannisyan; Ch. Hyde; C.W. de Jager; A. Ketikyan; V. Mamyan; R. Michaels; A.M. Nathan; V. Nelyubin; I. Rachek; M. Roedelbrom; A. Petrosyan; R. Pomatsalyuk; V. Popov; J. Segal; Yu. Shestakov; J. Templon; H. Voskanyan; B. Wojtsekhowski

2007-04-16

54

Choice of scatterer crystals to optimize the performance of Compton polarimeters  

Microsoft Academic Search

The response of two-crystal Compton gamma-ray polarimeters is compared in various 90° scattering geometries. The main factors affecting the quality of the data are the size of the scatterer crystal and its Compton profile. On sabbatical leave from: Laboratorie Van de Graaff, Département de Physique, Université Lava, Québec, P.Q., Canada G1K 7P4.

J. A. Cameron; I. M. Szöghy

1987-01-01

55

Compton X-Ray Scattering.  

National Technical Information Service (NTIS)

A new high precision method is developed for measuring Compton-line profiles quantitatively and to obtain the ratio of modified and unmodified radiation. The most important progress consisted in using monochromatic primary radiation produced by fluorescen...

A. Mueller D. Weick R. Hosemann

1973-01-01

56

Omnidirectional Induced Compton Scattering by Relativistic Electrons  

Microsoft Academic Search

Quasars, pulsars and other cosmic sources of intense radiation are known to have large brightness temperature (kT b≫mc 2) and relativistic electron density values. In this case the induced Compton scattering by relativistic electrons should be considered. The probability of scattering with decreasing radiation frequency is derived for isotropic radiation scattering. When induced scattering takes place, the relativistic electron obtains

V. M. Charugin; Yu. P. Ochelkov

1974-01-01

57

Recognition of Compton scattering patterns in advanced Compton telescopes  

NASA Astrophysics Data System (ADS)

The next generation of Compton telescopes (such as MEGA or NCT) will detect impinging gamma rays by measuring one or more Compton interactions, possibly electron tracks, and a final photo absorption. However, the recovery of the original parameters of the photon, especially its energy and direction, is a challenging task, since the measured data only consists of a set of energy and position measurements and their ordering, i.e. the path of the photon, is unknown. Thus the main tasks of the pattern recognition algorithm are to identify the interaction sequence of the photon (i.e. which hit is the start point) and distinguish the pattern from background signatures, especially incompletely absorbed events. The most promising approach up to now is based on Bayesian statistics: The Compton interactions are parameterized in a multi-dimensional data space, which contains the interaction information of the Compton sequence as well as geometry information of the detector. For each data space cell the probability that the corresponding interaction sequence is one of a correctly ordered, completely absorbed source photon can be determined by Bayesian statistics and detailed simulations. This probability can then be used to distinguish source photons from incompletely absorbed photons. Simulations show that the Bayesian approach can improve the 68% event containment of the ARM distribution by up to 40%, and results in a much better separation between "good" and "bad" events. In addition, sensitivity improvements up to a factor 1.7 can be achieved.

Zoglauer, Andreas; Boggs, Steven E.; Andritschke, Robert; Kanbach, Gottfried

2007-10-01

58

Gamma-ray polarimetry with Compton Telescope  

NASA Astrophysics Data System (ADS)

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, Hiroyasu; Madejski, Grzegorz; Mitani, Takefumi; Tanaka, Takaaki; Nakamura, Hidehito; Nakazawa, Kazuhiro; Takahashi, Tadayuki; Fukazawa, Yasushi; Kamae, Tuneyoshi; Kokubun, Motohide; Marlow, Daniel; Nomachi, Masaharu; do Couto e Silva, Eduardo

2004-10-01

59

Timelike Compton Scattering - A First Look (CLAS)  

SciTech Connect

A major goal of the 12 GeV upgrade at Jefferson Lab is to map out the Generalized Parton Distributions (GPDs) in the valence region. This is primarily done through Deeply Virtual Compton Scattering (DVCS), which provides the simplest and cleanest way of accessing the GPDs. However, the “inverse” process, Timelike Compton Scattering (TCS), can provide an important complement, in particular formeasuring the real part of the amplitude and understanding corrections at finite Q2. The first measurements of TCS have recently been carried out in Hall B at Jefferson Lab, using both tagged and untagged photon beams.

Pawel Nadel-Turonski

2009-12-01

60

Timelike Compton Scattering - A First Look  

SciTech Connect

A major goal of the 12 GeV upgrade at Jefferson Lab is to map out the Generalized Parton Distributions (GPDs) in the valence region. This is primarily done through Deeply Virtual Compton Scattering (DVCS), which provides the simplest and cleanest way of accessing the GPDs. However, the 'inverse' process, Timelike Compton Scattering (TCS), can provide an important complement, in particular for measuring the real part of the amplitude and understanding corrections at finite Q{sup 2}. The first measurements of TCS have recently been carried out in Hall B at Jefferson Lab, using both tagged and untagged photon beams.

Nadel-Turonski, P.; Klein, F. J. [Catholic University of America, Washington, DC 20064 (United States); Horn, T. [Catholic University of America, Washington, DC 20064 (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Ilieva, Y. [University of South Carolina, Columbia, SC 29208 (United States); Paremuzyan, R. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States); Yerevan Physics Institute, 375036 Yerevan (Armenia); Stepanyan, S. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

2009-12-17

61

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

62

Quark-nucleon dynamics and deep virtual Compton scattering  

SciTech Connect

We consider deeply virtual Compton scattering and deep inelastic scattering in presence of Regge exchanges that are part of the nonperturbative quark-nucleon amplitude. In particular we discuss contribution from the Pomeron exchange and demonstrate how it leads to Regge scaling of the Compton amplitude. A new fit of the deeply virtual Compton scattering total cross section data in HERA kinematics is proposed.

Gorchtein, M. [Center for the Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47408 (United States); Szczepaniak, A. P. [Center for the Exploration of Energy and Matter, Indiana University, Bloomington, Indiana 47408 (United States); Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States)

2010-07-01

63

Importance of Doppler broadening in Compton scatter imaging techniques  

NASA Astrophysics Data System (ADS)

Compton scattering is a potential tool for the determination of bone mineral content or tissue density for dose planning purposes, and requires knowledge of the energy distribution of the X-rays through biological materials of medical interest in the X-ray and (gamma) -ray region. The energy distribution is utilized in a number of ways in diagnostic radiology, for example, in determining primary photon spectra, electron densities in separate volumes, and in tomography and imaging. The choice of the X-ray energy is more related to X-ray absorption, where as that of the scattering angle is more related to geometry. The evaluation of all the contributions are mandatory in Compton profile measurements and is important in X-ray imaging systems in order to achieve good results. In view of this, Compton profile cross-sections for few biological materials are estimated at nineteen K(alpha) X-ray energies and 60 keV (Am-241) photons. Energy broadening, geometrical broadening from 1 to 180 degree(s), FWHM of J(Pz) and FWHM of Compton energy broadening has been evaluated at various incident photon energies. These values are estimated around the centroid of the Compton profile with an energy interval of 0.1 keV and 1.0 keV for 60 keV photons. The interaction cross sections for the above materials are estimated using fractions-by-weight of the constituent elements. Input data for these tables are purely theoretical.

Rao, Donepudi V.; Takeda, Tohoru; Itai, Yuji; Seltzer, S. M.; Hubbell, John H.; Zeniya, Tsutomu; Akatsuka, Takao; Cesareo, Roberto; Brunetti, Antonio; Gigante, Giovanni E.

2001-12-01

64

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

65

Anisotropic Inverse Compton Scattering in the Galaxy  

Microsoft Academic Search

The inverse Compton scattering of interstellar photons off cosmic-ray electrons seems to play a more important role in the generation of diffuse emission from the Galaxy than thought before. The background radiation field of the Galaxy is highly anisotropic since it is dominated by the radiation from the Galactic plane. An observer in the Galactic plane thus sees mostly head-on

Igor V. Moskalenko; Andrew W. Strong

2000-01-01

66

Shadowing in Compton scattering on nuclei  

SciTech Connect

We evaluate the shadowing effect in deeply virtual and real Compton scattering on nuclei in the framework of the color dipole model. We rely on the soft photon wave function derived in the instanton vacuum model and employ the impact parameter dependent phenomenological elastic dipole amplitude. Both the effects of quark and the gluon shadowing are taken into account.

Kopeliovich, B. Z.; 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)

2010-05-01

67

The Compton Gamma Ray Observatory: mission status.  

NASA Astrophysics Data System (ADS)

The Arthur Holly Compton Gamma Ray Observatory (Compton) is the second in NASA's series of Great Observatories. Compton has now been operating for over two and a half years, and has given a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments are all in good health, and many significant discoveries have already been made and continue to be made. The authors describe the capabilities of the four scientific instruments and the observing programs for the first three years of the mission. During Phases 2 and 3 of the mission a Guest Investigator program has been in progress with the Guest Observers' time share increasing from 30% to over 50% for the later mission phases.

Gehrels, N.; Chipman, E.; Kniffen, D. A.

68

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

69

Compton scattering sequence reconstruction algorithm for the liquid xenon gamma-ray imaging telescope (LXeGRIT)  

Microsoft Academic Search

The Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT) is a balloon born experiment sensitive to (gamma) -rays in the energy band of 0.2 - 20 MeV. The main detector is a time projection chamber filled with high purity liquid xenon (LXeTPC), in which the three-dimensional location and energy deposit of individual (gamma) -ray interactions are accurately measured in one homogeneous volume.

Uwe G. Oberlack; Elena Aprile; Alessandro Curioni; Valeri Egorov; Karl-Ludwig Giboni

2000-01-01

70

On the Synchrotron Self-Compton Emission from Relativistic Shocks and Its Implications for Gamma-Ray Burst Afterglows  

Microsoft Academic Search

We consider the effects of inverse Compton scattering of synchrotron photons from relativistic electrons in gamma-ray burst (GRB) afterglows. We compute the spectrum of the inverse Compton emission and find that it can dominate the total cooling rate of the afterglow for several months or even years after the initial explosion. We demonstrate that the presence of strong inverse Compton

Re'em Sari; Ann A. Esin

2001-01-01

71

Induced Compton-scattering effects in radiation-transport approximations  

SciTech Connect

The method of characteristics is used to solve radiation transport problems with induced Compton scattering effects included. The methods used to date have only addressed problems in which either induced Compton scattering is ignored, or problems in which linear scattering is ignored. Also, problems which include both induced Compton scattering and spatial effects have not been considered previously. The introduction of induced scattering into the radiation transport equation results in a quadratic nonlinearity. Methods are developed to solve problems in which both linear and nonlinear Compton scattering are important. Solutions to scattering problems are found for a variety of initial photon energy distributions.

Gibson, D.R. Jr.

1982-02-01

72

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

73

Neutron polarizabilities investigated by quasifree Compton scattering from the deuteron.  

PubMed

Measuring Compton scattered photons and recoil neutrons in coincidence, quasifree Compton scattering by the neutron has been investigated at MAMI (Mainz) at theta(lab)(gamma) = 136 degrees in an energy range from 200 to 400 MeV. From the data a polarizability difference of alpha(n)-beta(n) = 9.8+/-3.6(stat)+2.1-1.1(syst)+/-2.2(model) in units of 10(-4) fm(3) has been determined. In combination with the polarizability sum alpha(n)+beta(n) = 15.2+/-0.5 deduced from photoabsorption data, the first precise results for the neutron electric and magnetic polarizabilities, alpha(n) = 12.5+/-1.8(stat)+1.1-0.6(syst)+/-1.1(model) and beta(n) = 2.7-/+1.8(stat)+0.6-1.1(syst)-/+1.1(model), are obtained. PMID:11955229

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

2002-04-08

74

Deeply virtual Compton scattering off nuclei  

SciTech Connect

Deeply virtual Compton scattering (DVCS) is the golden exclusive channel for the study of the partonic structure of hadrons, within the universal framework of generalized parton distributions (GPDs). This paper presents the aim and general ideas of the DVCS experimental program off nuclei at the Jefferson Laboratory. The benefits of the study of the coherent and incoherent channels to the understanding of the EMC (European Muon Collaboration) effect are discussed, along with the case of nuclear targets to access neutron GPDs.

Voutier, Eric

2009-01-01

75

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

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

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

78

High-energy scaling of Compton scattering light sources  

Microsoft Academic Search

No monochromatic (Deltaomegax\\/omegax1020photons\\/(mm2×mrad2×s×0.1%bandwidth)], tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard x-ray and gamma-ray sources include the following: nuclear resonance fluorescence spectroscopy and isotopic imaging, time-resolved positron annihilation spectroscopy, and MeV flash radiography. In this paper, the peak brightness of Compton scattering light sources is derived for head-on collisions and found

F. V. Hartemann; W. J. Brown; D. J. Gibson; S. G. Anderson; A. M. Tremaine; P. T. Springer; A. J. Wootton; E. P. Hartouni; C. P. J. Barty

2005-01-01

79

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

80

Exclusive Compton Scattering on the Proton  

SciTech Connect

An experiment is proposed to measure the cross sections for Real Compton Scattering from the proton in the energy range 3-6 GeV and over a wide angular range; and to measure the longitudinal and transverse components of the polarization transfer to the recoil proton at a single kinematic point. Together; these measurements will test models of the reaction mechanism and determine new structure functions of the proton that are related to the same nonforward parton densities that determine the elastic electron scattering form factors and the parton densities. The experiment utilizes an untagged bremsstrahlung photon beam and the standard Hall A cryogenic targets. The scattered photon is detected in a photon spectrometer; currently under construction. The coincident recoil proton is detected in one of the Hall A magnetic spectrometers and its polarization components are measured in the existing Focal Plane Polarimeter. This proposal extends and supercedes E97-108 which was approved by PAC13.

J. P. Chen; E. Chudakov; C. DeJager; P. Degtyarenko; R. Ent; J. Gomez; O. Hansen; C. Keppel; F. Klein; M. Kuss; J. LeRose; M. Liang; R. Michaels; J. Mitchell; N. Liyanage; P. Rutt; A. Saha; B. Wojtsekhowski; M. Bouwhuis; TH Chang; R. J. Holt; A. M. Nathan; M. Roedelbronn; K. Wijesooriya; S. E. Williamson; G. Dodge; C. Hyde-Wright; A. Radyushkin; F. Sabatie; L. B. Weinstein; P. Ulmer; P. Bosted; J. M. Finn; M. Jones; S. Churchwell; C. Howell; R. Gilman; C. Glashausser; X. Jiang; R. Ransome; S. Strauch; J. Berthot; P. Bertin; H. Fonvielle; Y. Roblin; W. Bertozzi; S. Gilad; D. Rowntree; Z. Zu; D. Brown; G. Chang; A. Afanasev; K. Egiyan; E. Hoohauneysan; A. Ketikyan; S. Mailyan; A. Petrosyan; A. Shahinyan; H. Voskanyan; W. Boeglin; P. Markowitz; J. Hines; G. Strobel; J. Templon; G. Feldman; C. L. Morris; V. Gladyshev; R. A. Lindgren; J. Calarco; W. Hersman; M. Leuschner; A. Gasparian

1999-06-08

81

Deeply virtual Compton scattering at Jefferson Lab  

SciTech Connect

The Generalized Parton Distribution framework was introduced in the late 90’s and describes the nucleon in a revolutionary way, correlating the information from both momentum and transverse position space into experimentally accessible functions. After a brief introduction, this article reviews the Jefferson Lab 6 GeV measurements of Deeply Virtual Compton Scattering in Halls A and B, which give a unique access to Generalized Parton Distributions (GPD). The second part of this article reviews the Jefferson Lab 12 GeV upgrade in general terms, and then focuses on the GPD program in Halls A and B.

Franck Sabatie

2010-01-01

82

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

83

Beam dynamics in Compton ring gamma sources  

NASA Astrophysics Data System (ADS)

Electron storage rings of GeV energy with laser pulse stacking cavities are promising intense sources of polarized hard photons which, via pair production, can be used to generate polarized positron beams. In this paper, the dynamics of electron bunches circulating in a storage ring and interacting with high-power laser pulses is studied both analytically and by simulation. Both the common features and the differences in the behavior of bunches interacting with an extremely high power laser pulse and with a moderate pulse are discussed. Also considerations on particular lattice designs for Compton gamma rings are presented.

Bulyak, Eugene; Gladkikh, Peter; Skomorokhov, Vladislav; Omori, Tsunehiko; Urakawa, Junji; Moenig, Klaus; Zimmermann, Frank

2006-09-01

84

The imaging compton telescope COMPTEL on the gamma ray observatory  

SciTech Connect

This instrument is based on a newly established concept of ..gamma..-ray detection in the very difficult 1-30 MeV range. It employs the unique feature of a two-step interaction of the ..gamma..-ray: a Compton scattering collision in a first detector followed by an interaction in a second detector element. COMPTEL has been designed to perform a very sensitive survey of the ..gamma..-ray sky. Extreme care has been taken to minimize background so that the detection limits of COMPTEL will be dominated by source counting statistics. It combines a wide field of view (about 1 steradian) with a good angular resolution. The design criteria of COMPTEL and the performance of a Science Model are described.

Schonfelder, V.; Aarts, H.; Deerenberg, A.J.M.; Diehl, R.; Lichti, G.G.; Lockwood, J.; Steinle, H.; Swanburg, B.N.

1984-02-01

85

Characterization of breast tissues using Compton scattering  

NASA Astrophysics Data System (ADS)

In this work we measured Compton X-ray scatter signals from normal (adipose and fibrous) and neoplastic (benign and malignant) breast tissues using a photon energy of 17.44 keV (K? radiation of Mo) and a scattering angle of 90° (x=0.99 Å-1), in order to determine their electron densities. The results of electron densities obtained were compared with experimental and theoretical data published previously, showing considerable agreement among them (differences smaller than 5%). Statistical comparisons were made using the obtained distributions, showing that normal adipose breast tissue clearly differ from all other types of tissues. Finally, the results were discussed on the basis of histological and metabolic characteristics of these tissue types.

Antoniassi, M.; Conceição, A. L. C.; Poletti, M. E.

2010-07-01

86

A compton polarimeter constructed with a large Si(Li) scatterer and two Ge analysers  

Microsoft Academic Search

A Compton polarimeter has been constructed with a large Si(Li) scatterer and two Ge analysers. Using a Monte Carlo method the characteristics of the Si(Li) scatterer were compared with a Ge scatterer having the same size. The calculations show that the Si(Li) scatterer is very suited for low-energy gamma-rays below 300 keV. The polarization sensitivity has been measured in the

S. Ohya; H. Miura; K. Nishimura; N. Mutsuro; T. Aoki

1989-01-01

87

Nonforward Compton scattering in AdS/CFT correspondence  

SciTech Connect

We study the nonforward Compton scattering, in particular, the deeply virtual Compton scattering from AdS/CFT. We first calculate the contributions from the s-channel and u-channel supergravity diagrams as well as the four-point interaction diagram which correspond to the Compton scatterings on a dilaton target in CFT. Furthermore, we study the Compton scattering on a dilatino target. Assuming that protons can be identified as supergravity modes of the dilatino, we compare the calculated deeply virtual Compton scattering cross section to the low-energy experimental data from the H1 and ZEUS collaborations and find good agreement. We also discuss the t-channel graviton exchange contribution and show that it should be dominant in the high-energy limit.

Gao Jianhua; Xiao Bowen [Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Nuclear Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2010-02-01

88

Magnetic Compton scattering near a hot neutron star polar CAP  

NASA Astrophysics Data System (ADS)

We presents results of a model for the energetics of electrons accelerated away from a neutron star polar cap by the large electric fields generated by the rotating highly magnetized neutron star. The energy loss mechanisms we consider in our calculations include magnetic Compton scattering of thermal X-ray photons, triplet pair production, and curvature radiation emission. The electron acceleration mechanism is assumed to operate only to a height above the polar cap approximately equal to the polar cap radius. We find several interesting results. First, magnetic Compton scattering is the dominant energy loss process when the electron Lorentz factors are below 107 for typical gamma-ray pulsar magnetic fields and surface temperatures. The amount of energy converted to photons by accelerated electrons ranges from approximately 10-100% of gammao mc2 for pulsar parameters similar to those observed where gammao is the maximum Lorentz factor an electron can attain with no radiative losses. We also find that if B is greater than 1013 G and T is greater than 3 x 10(exp6)K, the Lorentz factors of the electrons can be limited to values of 102-103 assuming values for the size of the neutron star thermal polar cap comparable to the polar cap size determined by the open field lines. Such small Lorentz factors may be capable of explaining the gamma-ray emission from PSR 1509-58 which is observed only to about 1 MeV.

Sturner, S. J.; Dermer, C. D.

1995-05-01

89

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

90

Application of 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 the intense cesium gamma ray. 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.

McIlwain, Michael

2004-06-01

91

Small-angle Compton Scattering to Determine the Depth of a Radioactive Source in Matter  

SciTech Connect

A gamma-ray peak in a spectrum is often accompanied by a discontinuity in the Compton continuum at the peak. The Compton continuum results from Compton scattering in the detector. The discontinuity at a peak results from small-angle Compton scattering by the gamma rays in matter situated directly between the gamma-ray source and the detector. The magnitude of this discontinuity with respect to the gamma-ray peak is therefore an indicator of the amount of material or shielding between the gamma-ray source and the detector. This small-angle scattering was used to determine the depth of highly-enriched uranium (HEU) solution standards in a concrete floor mockup. The empirical results of the use of this small-angle scattering discontinuity in a concrete floor experiment will be described. A Monte Carlo calculation of the experiment will also be described. In addition, the depth determined from small-angle scattering was used in conjunction with differential attenuation to more accurately measure the uranium content of the mockup. Following these empirical results, the theory of small-angle scattering will be discussed. The magnitude of the discontinuity compared to the peak count rate is directly related to the depth of the gamma-ray source in matter. This relation can be described by relatively simple mathematical expressions. This is the first instance that we are aware of in which the small-angle Compton scattering has been used to determine the depth of a radioactive source. Furthermore this is the first development of the theoretical expressions for the magnitude of the small-angle scattering discontinuity.

Oberer, R. B.; Gunn, C. A.; Chiang, L. G.; Valiga, R. E.; Cantrell, J. A.

2011-04-01

92

Compton scattering in fluorescent Fe K line profiles  

NASA Astrophysics Data System (ADS)

We discuss the recent progress in modeling of X-ray irradiated atmospheres, where radiative transfer of both external radiation and self radiation of affected gas are computed. We present model atmospheres in both radiative and hydrostatic equilibrium, which include precise treatment of multiple Compton scattering process. Outgoing continuum spectra of our models demonstrate the effects of Compton redistribution of hard X-rays to lower energies. These spectra include also detailed profiles of fluorescent iron K? lines, which are broadened and distorted by Compton scattering. Model spectra exhibit distinct Compton shoulders from the red side of the line with equivalent widths of the order of 50 eV.

Ró?a?ska, A.; Madej, J.

2005-06-01

93

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

94

Quasifree compton scattering from the deuteron and nucleon polarizabilities  

PubMed

Cross sections for quasifree Compton scattering from the deuteron were measured for incident energies of E(gamma) = 236-260 MeV at the laboratory angle straight theta(gamma(')) = -135 degrees. The recoil nucleons were detected in a liquid-scintillator array situated at straight theta(N) = 20 degrees. The measured differential cross sections were used, with the calculations of Levchuk et al., to determine the polarizabilities of the bound nucleons. For the bound proton, the extracted values were consistent with the accepted value for the free proton. Combining our results for the bound neutron with those from Rose et al., we obtain 1-sigma constraints of alpha;(n) = 7.6-14.0 and beta;(n) = 1.2-7.6. PMID:10970511

Kolb; Rauf; Igarashi; Hornidge; Pywell; Warkentin; Korkmaz; Feldman; O'Rielly

2000-08-14

95

Compton scattering profile for in vivo XRF techniques.  

PubMed

The contribution from single Compton scattered photons to the background in in vivo x-ray fluorescence analysis is evaluated by taking into account the energy broadening of the scattered photons which reflects the momentum distribution of the target electrons. A general-purpose Monte Carlo evaluation of multiple scattering components, as well as accurate experimental verifications with 59.54 keV photons impinging on various targets of interest for real-life irradiation, confirm that the single Compton scattering profiles of the elements composing the biological matrix dominate the trend and amplitude of the background in the region of interest with near-backscatter configurations. Step features are likewise explained in terms of single Compton phenomenology. Other probable sources of background, such as photoelectron Bremsstrahlung and pile-up distribution, are studied both theoretically and experimentally in order to compare their amplitude and features with those of single Compton scattered photon profiles. PMID:2068224

Tartari, A; Baraldi, C; Felsteiner, J; Casnati, E

1991-05-01

96

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

Microsoft Academic Search

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

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

2012-01-01

97

Balloon-borne sub-MeV\\/MeV gamma-ray observation using a Compton camera with a gaseous TPC and scintillation camera  

Microsoft Academic Search

We have developed a sub-MeV and MeV gamma-ray imaging Compton camera for use in gamma-ray astronomy; it consists of a gaseous time-projection chamber (TPC) to convert the Compton scattering events and a scintillator array to absorb photons. The TPC measures the energy and three-dimensional tracks of Compton-recoil electrons, while the pixel scintillator arrays measure the energy and positions of scattered

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

2010-01-01

98

Electronic structure of methane hydrate studied by Compton scattering  

SciTech Connect

High-resolution Compton scattering spectra of methane, methane hydrate, and ice were measured using incident photon energy of 56.4 keV at beamline ID15B of the European Synchrotron Radiation Facility. The experimental Compton profiles are compared to calculations employing density-functional theory using model atomic clusters. The hydrate has a cagelike structure built up from water molecules and the related Compton profile is observed to change apparently when compared to hexagonal ice. Furthermore, the influence of the guest-host interactions between the methane molecules and the water molecules of the cages on the Compton profile is discussed.

Sternemann, C.; Paulus, M.; Volmer, M.; Gutt, C.; Tolan, M. [Department of Physics/DELTA, University of Dortmund, D-44221 Dortmund (Germany); Huotari, S.; Buslaps, T.; Hiraoka, N. [European Synchrotron Radiation Facility, Boite Postale 220, F-38043 Grenoble Cedex (France); Hakala, M.; Haemaelaeinen, K. [Department of Physical Sciences, P.O. Box 64, FI-00014, University of Helsinki, Helsinki (Finland); Klug, D. D. [Stacie Institute of Molecular Science, National Research Council of Canada, Ottawa, Ontario, Canada K1A OR6 (Canada); Tse, J. S. [Department of Physics and Engineering Physics, University of Saskatchewan, Saskatoon, Canada S7N 5E2 (Canada)

2006-05-15

99

Double deeply virtual Compton scattering on nucleons and nuclei  

SciTech Connect

In this paper we evaluate the double deeply virtual Compton scattering on nucleons and nuclei in the framework of the color dipole model. Both the effects of quark and the gluon shadowing are taken into account.

Kopeliovich, B. Z.; 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)

2010-07-01

100

Compton scattering of blackbody photons by relativistic electrons  

NASA Astrophysics Data System (ADS)

We present simple and accurate analytical formulas for the rates of Compton scattering by relativistic electrons integrated over the energy distribution of blackbody seed photons. Both anisotropic scattering, in which blackbody photons arriving from one direction are scattered by an anisotropic electron distribution into another direction, and scattering of isotropic seed photons are considered. Compton scattering by relativistic electrons off blackbody photons from either stars or cosmic microwave background takes place, in particular, in microquasars, colliding-wind binaries, supernova remnants, interstellar medium and the vicinity of the Sun.

Zdziarski, Andrzej A.; Pjanka, Patryk

2013-10-01

101

Compton scatter in frequency space: a theoretical study  

Microsoft Academic Search

For x-ray detectors, Compton interactions deposit photon energies along the paths of recoil electrons, which are not isotropic about the primary interaction sites. Light from each interacting x-ray is only generated near the path of a recoil electron. In this study, Compton scatter is modeled as an input-labeled cascade of the amplification and scattering processes to describe the transfer relationship

Jingwu Yao; Ian A. Cunningham

2002-01-01

102

Advanced Compton scattering light source R&D at LLNL  

Microsoft Academic Search

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. At MeV photon energies relevant for nuclear processes, Compton scattering light sources are attractive because of their relative compactness and improved brightness above 100 keV, compared to

F Albert; S G Anderson; G Anderson; S M Betts; T S Chu; D J Gibson; R A Marsh; M Messerly; M Y Shverdin; S Wu; F V Hartemann; C W Siders; C P Barty

2010-01-01

103

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

104

Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries  

SciTech Connect

The beam-spin asymmetries in the hard exclusive electroproduction of photons on the proton (e-vectorp{yields}ep{gamma}) 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{sub B} from 0.11 to 0.58, Q{sup 2} from 1 to 4.8 GeV{sup 2}, -t from 0.09 to 1.8 GeV{sup 2}), the azimuthal dependence of the asymmetries is compatible with expectations from leading-twist dominance, A{approx_equal}asin{phi}/(1+ccos{phi}). This extensive set of data can thus be used to constrain significantly the generalized parton distributions of the nucleon in the valence quark sector.

Girod, F. X. [CEA-Saclay, Service de Physique Nucleaire, 91191 Gif-sur-Yvette (France); Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Niyazov, R. A.; Kubarovsky, V. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States); Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States); Avakian, H.; Burkert, V. D.; Elouadrhiri, L.; Stepanyan, S.; Boiarinov, S.; Brooks, W. K.; Carman, D. S.; Degtyarenko, P. V.; Deur, A.; Egiyan, H.; Guo, L.; Gyurjyan, V.; Ito, M. M.; Laget, J. M.; Mecking, B. A.; Mestayer, M. D.; Niczyporuk, B. B. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)] (and others)

2008-04-25

105

Scaling laws in high-energy inverse Compton scattering  

SciTech Connect

Based upon the rate equations for the photon distribution function obtained in the previous paper, we study the inverse Compton scattering process for high-energy nonthermal electrons. Assuming the power-law electron distribution, we find a scaling law in the probability distribution function P{sub 1}(s), where the peak height and peak position depend only on the power-index parameter. We solved the rate equation analytically. It is found that the spectral intensity function also has the scaling law, where the peak height and peak position depend only on the power-index parameter. The present study will be particularly important to the analysis of the X-ray and gamma-ray emission models from various astrophysical objects such as radio galaxies and supernova remnants.

Nozawa, Satoshi; Kohyama, Yasuharu; Itoh, Naoki [Josai Junior College, 1-1 Keyakidai, Sakado-shi, Saitama, 350-0295 (Japan); Department of Physics, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 (Japan)

2010-02-15

106

Compton scattering studies of 4f ferromagnetism  

NASA Astrophysics Data System (ADS)

Ferromagnetism can be studied in Compton scattering experiments, which use high-energy, elliptically polarised synchrotron radiation. The basis of the method and its interpretation in terms of site-specific moments will be explained and illustrated by a series of examples of archetypal compounds. For example, the hexaborides exhibit a wide range of electronic properties. Data will be presented for the heavy Fermion system CeB6 and the controversial ferromagnet Ca1-xLaxB6. Undoped CeB6 exhibits a delocalised spin moment, more characteristic of the 5d than the 4f orbital. Whereas the magnetism in the Ca1-xLaxB6 system has been suggested to be an extrinsic effect arising from iron contamination, our data indicate that the magnetism is intrinsic and inconsistent with what would be expected for an iron 3d moment. This supports the proposal that this system is, indeed, a weak itinerant ferromagnet. In Ru2SrGdCu208, we observe a combination of Gd 4f, Gd 5d and Ru 4d moments and the 5d moment appears to flip orientation below the Néel temperature.

Cooper, M. J.; Duffy, J. A.; Banfield, Z. F.; Bebb, A. M.; Blaauw, L.; Shenton-Taylor, C.; Steer, C.; Taylor, J. W.

2006-11-01

107

500 MW X-Band RF System of a 0.25 GEV Electron Linac for Advanced Compton Scattering Source Application.  

National Technical Information Service (NTIS)

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 ...

C. Adolphsen C. Siders C. P. J. Barty D. J. Gibson F. V. Hartemann R. A. Marsh S. G. Anderson T. S. Chu

2012-01-01

108

Compton scattering of self-absorbed synchrotron emission  

NASA Astrophysics Data System (ADS)

Synchrotron self-Compton (SSC) scattering is an important emission mechanism in many astronomical sources, such as gamma-ray bursts (GRBs) and active galactic nuclei. We give a complete presentation of the analytical approximations for the Compton scattering of synchrotron emission with both weak and strong synchrotron self-absorption. All possible orders of the characteristic synchrotron spectral breaks (?a, ?m and ?c) are studied. In the weak self-absorption regime, i.e. ?a < ?c, the electron energy distribution is not modified by the self-absorption process. The shape of the SSC component broadly resembles that of synchrotron, but with the following features: The SSC flux increases linearly with frequency up to the SSC break frequency corresponding to the self-absorption frequency ?a; and the presence of a logarithmic term in the high-frequency range of the SSC spectra makes it harder than the power-law approximation. In the strong absorption regime, i.e. ?a > ?c, heating of low-energy electrons due to synchrotron absorption leads to pile-up of electrons, and form a thermal component besides the broken power-law component. This leads to two-component (thermal + non-thermal) spectra for both the synchrotron and SSC spectral components. For ?c < ?a < ?m, the spectrum is thermal (non-thermal) dominated if ? _a > ?{? _m ? _c} (? _a < ?{? _m ? _c}). Similar to the weak-absorption regime, the SSC spectral component is broader than the simple broken power-law approximation. We derive the critical condition for strong absorption (electron pile-up), and discuss a case of GRB reverse shock emission in a wind medium, which invokes ?a > max(?m, ?c).

Gao, He; Lei, Wei-Hua; Wu, Xue-Feng; Zhang, Bing

2013-11-01

109

Compton scattering of self-absorbed synchrotron emission  

NASA Astrophysics Data System (ADS)

Synchrotron self-Compton (SSC) scattering is an important emission mechanism in many astronomical sources, such as gamma-ray bursts (GRBs) and active galactic nuclei. We give a complete presentation of the analytical approximations for the Compton scattering of synchrotron emission with both weak and strong synchrotron self-absorption. All possible orders of the characteristic synchrotron spectral breaks (?a, ?m and ?c) are studied. In the weak self-absorption regime, i.e. ?a < ?c, the electron energy distribution is not modified by the self-absorption process. The shape of the SSC component broadly resembles that of synchrotron, but with the following features: The SSC flux increases linearly with frequency up to the SSC break frequency corresponding to the self-absorption frequency ?a; and the presence of a logarithmic term in the high-frequency range of the SSC spectra makes it harder than the power-law approximation. In the strong absorption regime, i.e. ?a > ?c, heating of low-energy electrons due to synchrotron absorption leads to pile-up of electrons, and form a thermal component besides the broken power-law component. This leads to two-component (thermal + non-thermal) spectra for both the synchrotron and SSC spectral components. For ?c < ?a < ?m, the spectrum is thermal (non-thermal) dominated if ? _a > sqrt{? _m ? _c} (? _a < sqrt{? _m ? _c}). Similar to the weak-absorption regime, the SSC spectral component is broader than the simple broken power-law approximation. We derive the critical condition for strong absorption (electron pile-up), and discuss a case of GRB reverse shock emission in a wind medium, which invokes ?a > max(?m, ?c).

Gao, He; Lei, Wei-Hua; Wu, Xue-Feng; Zhang, Bing

2013-09-01

110

Nucleon Compton scattering in the Dyson-Schwinger approach  

NASA Astrophysics Data System (ADS)

We analyze the nucleon’s Compton scattering amplitude in the Dyson-Schwinger/Faddeev approach. We calculate a subset of diagrams that implements the nonperturbative handbag contribution as well as all t-channel resonances. At the quark level, these ingredients are represented by the quark Compton vertex whose analytic properties we study in detail. We derive a general form for a fermion two-photon vertex that is consistent with its Ward-Takahashi identities and free of kinematic singularities, and we relate its transverse part to the on-shell nucleon Compton amplitude. We solve an inhomogeneous Bethe-Salpeter equation for the quark Compton vertex in rainbow-ladder truncation and implement it in the nucleon Compton scattering amplitude. The remaining ingredients are the dressed quark propagator and the nucleon’s bound-state amplitude which are consistently solved from Dyson-Schwinger and covariant Faddeev equations. We verify numerically that the resulting quark Compton vertex and nucleon Compton amplitude both reproduce the ??? transition form factor when the pion pole in the t channel is approached.

Eichmann, Gernot; Fischer, Christian S.

2013-02-01

111

Observations of GRB 990123 by the Compton Gamma Ray Observatory  

Microsoft Academic Search

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

M. S. Briggs; D. L. Band; R. M. Kippen; R. D. Preece; C. Kouveliotou; J. van Paradijs; G. H. Share; R. J. Murphy; S. M. Matz; A. Connors; C. Winkler; M. L. McConnell; J. M. Ryan; O. R. Williams; C. A. Young; B. Dingus; J. R. Catelli; R. A. M. J. Wijers

1999-01-01

112

Enhancement of Compton scattering by an effective coupling constant  

SciTech Connect

A robust thermodynamic argument shows that a small reduction of the effective coupling constant {alpha} of QED greatly enhances the low-energy Compton-scattering cross section and that the Thomson scattering length is connected to a fundamental scale {lambda}. A discussion provides a possible quantum interpretation of this enormous sensitivity to changes in the effective coupling constant {alpha}.

Barbiellini, Bernardo; Nicolini, Piero [Department of Physics, Northeastern University, Boston, Massachusetts 02115 (United States); Frankfurt Institute for Advanced Studies (FIAS), Institut fuer Theoretische Physik, Johann Wolfgang Goethe-Universitaet, Ruth-Moufang-Strasse 1, DE-60438 Frankfurt am Main (Germany)

2011-08-15

113

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

114

Compton scattering of elemental silicon at high pressure  

NASA Astrophysics Data System (ADS)

The electronic structure of elemental silicon has been studied under high pressure using high-energy Compton scattering utilizing synchrotron radiation. The experiment was realized using a special Laue monochromator and a novel assembly of compound refractive lenses. The extremely good focusing enabled us to utilize a Mao-Bell version of the Merrill-Basset diamond anvil cell with a Be gasket up to a pressure of 20 GPa. After the careful subtraction of background scattering, the Compton profile difference for the metastable Si-XII to the Si-V phase was extracted and compared with the theory. The results clearly demonstrate the feasibility and potential of the Compton scattering technique as a complementary tool in the study of electronic structure of materials under high pressure.

Tse, J. S.; Klug, D. D.; Jiang, D. T.; Sternemann, C.; Volmer, M.; Huotari, S.; Hiraoka, N.; Honkimäki, V.; Hämäläinen, K.

2005-11-01

115

Compton Gamma Ray Observatory/BATSE observations of energetic electrons scattered by cyclotron resonance with waves from powerful VLF transmitters. Final report, 13 October 1992-12 February 1994  

SciTech Connect

To obtain a better understanding of the wave-particle mechanisms responsible for the loss of electrons from the radiation belts, energetic electron data from the Burst and Transient Source Experiment (BATSE) on the NASA's Compton Gamma Ray Observatory (GRO) was studied. Powerful ground-based VLF transmitters resonantly scatter electrons from the inner radiation belt onto trajectories from which they precipitate into the atmosphere as they drift eastward. 563 instances in which the satellite traversed a cloud of energetic electrons which had been scattered into quasi-trapped trajectories were identified. From the longitude distribution, it was concluded that waves from the VLF transmitter NWC at 114 deg E are the origin of 257 of the events, and waves from UMSat 44 deg E related to 45 more. In another 177 cases the electrons had drifted from the longitude of these transmitters to a location in the western hemisphere. The previously reported seasonal variation in the frequency of occurrence of cyclotron resonance interaction is confirmed with the continuous coverage provided by GRO. The frequency of occurrence of the cyclotron resonance interactions is largest before sunrise, which the authors attribute to the diurnal variations in the transmission VLF waves through the ionosphere. For the first time, unique very narrow sheets of electrons occurring in the aftermath of a large geomagnetic storm are reported.

Datlowe, D.W.; Imhof, W.L.

1994-02-01

116

Compton scattering by a pion and off-shell effects  

NASA Astrophysics Data System (ADS)

We consider Compton scattering by a pion in the framework of chiral perturbation theory. We investigate off-shell effects in the s- and u-channel pole diagrams. For that purpose we perform a field transformation which, in comparison with the standard Gasser and Leutwyler Lagrangian, generates additional terms at order p4 proportional to the lowest-order equation of motion. As a result of the equivalence theorem the two Lagrangians predict the same Compton scattering S-matrix even though they generate different off-shell form factors. We conclude that off-shell effects are not only model dependent but also representation dependent.

Scherer, S.; Fearing, H. W.

1995-01-01

117

Compton scattering by a pion and off-shell effects  

SciTech Connect

We consider Compton scattering by a pion in the framework of chiral perturbation theory. We investigate off-shell effects in the [ital s]- and [ital u]-channel pole diagrams. For that purpose we perform a field transformation which, in comparison with the standard Gasser and Leutwyler Lagrangian, generates additional terms at order [ital p][sup 4] proportional to the lowest-order equation of motion. As a result of the equivalence theorem the two Lagrangians predict the same Compton scattering [ital S]-matrix even though they generate different off-shell form factors. We conclude that off-shell effects are not only model dependent but also representation dependent.

Scherer, S.; Fearing, H.W. (TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada))

1995-01-01

118

Investigation Into the Noninvasive Assessment of Bone Density Using Multiplexed Compton Scattered Tomography.  

National Technical Information Service (NTIS)

The purpose of this research is to investigate the application of a Compton scatter imaging technique to measure bone density. A demonstration Multiplexed Compton Scatter Tomograph (MCST) was assembled to demonstrate the feasibility of detecting osteoporo...

M. J. Sands

1999-01-01

119

Effective atomic number in the Rayleigh to Compton scattering ratio  

NASA Astrophysics Data System (ADS)

Detection and counting X-ray photons scattered by the Rayleigh and Compton processes enable matter to be characterized locally. A theoretical relation was first established which simulates the result of a Rayleigh to Compton ratio measurement. It can thus be shown that a correct choice of scattering angle and photon energy enables a result to be obtained which is almost independent of X-ray attenuation inside the sample. With this condition, the Rayleigh to Compton scattering ratio depends only on the mixture under study and provides a local measurement of certain complicated functions of the atomic number Z and of the weight percentage of the different elements which constitute the compound. This function is usually called the ``effective atomic number'', Zeff. Different methods of calculation of Zeff are found in the literature, four of them, those used most frequently, were tested. There is no unique relation between the computed Zeff and 80 experimental results performed on aqueous solutions with different concentrations of eight elements, having Z values ranging from 13 to 64. This observation led us to the conclusion that any effective atomic number is valid only for given experimental conditions. Finally, a new method of calculating Zeff was developed for the Rayleigh to Compton scattering ratio, which is applicable for any material, scattering angle or photon energy.

Duvauchelle, P.; Peix, G.; Babot, D.

120

Nonorthogonal gamma-ray compton polarimeters  

Microsoft Academic Search

An appropriate parameterization of the relation between the counting rate asymmetry and the degree of polarization is derived for Compton polarimeters not having orthogonal symmetry. The question of the usefulness of such polarimeters is addressed using the concept of merit and exemplified with the case of the EUROBALL CLUSTER detector.

L. M. Garcia-Raffi; J. L. Tain; J. Bea; A. Gadea; L. Palafox; J. Rico; B. Rubio

1995-01-01

121

First measurement of pie>pi-egamma pion virtual compton scattering  

Microsoft Academic Search

Pion virtual compton scattering (VCS) via the reaction pi-e-->pi-egamma was observed in the Fermilab E781 SELEX experiment. SELEX used a 600 GeV\\/c pi- beam incident on target atomic electrons, detecting the incident pi- and the final state pi-, electron and gamma. Theoretical predictions based on chiral perturbation theory are incorporated into a Monte Carlo simulation of the experiment and are

A. Ocherashvili; G. Alkhazov; A. G. Atamantchouk; M. Y. Balatz; N. F. Bondar; P. S. Cooper; L. J. Dauwe; G. V. Davidenko; U. Dersch; A. G. Dolgolenko; G. B. Dzyubenko; R. Edelstein; L. Emediato; A. M. Endler; J. Engelfried; I. Eschrich; C. O. Escobar; A. V. Evdokimov; I. S. Filimonov; F. G. Garcia; M. Gaspero; I. Giller; V. L. Golovtsov; P. Gouffon; E. Gülmez; He Kangling; M. Iori; S. Y. Jun; M. Kaya; J. Kilmer; V. T. Kim; L. M. Kochenda; I. Konorov; A. P. Kozhevnikov; A. G. Krivshich; H. Krüger; M. A. Kubantsev; V. P. Kubarovsky; A. I. Kulyavtsev; N. P. Kuropatkin; V. F. Kurshetsov; A. Kushnirenko; S. Kwan; J. Lach; A. Lamberto; L. G. Landsberg; I. Larin; E. M. Leikin; Li Yunshan; M. Luksys; T. Lungov; V. P. Maleev; D. Mao; Mao Chensheng; Mao Zhenlin; P. Mathew; M. Mattson; V. Matveev; E. McCliment; M. A. Moinester; V. V. Molchanov; A. Morelos; K. D. Nelson; A. V. Nemitkin; P. V. Neoustroev; C. Newsom; A. P. Nilov; S. B. Nurushev; Y. Onel; E. Ozel; S. Ozkorucuklu; A. Penzo; S. I. Petrenko; P. Pogodin; B. Pouh; M. Procario; V. A. Prutskoi; E. Ramberg; G. F. Rappazzo; B. V. Razmyslovich; V. I. Rud; J. Russ; P. Schiavon; J. Simon; A. I. Sitnikov; D. Skow; V. J. Smith; M. Srivastava; V. Steiner; V. Stepanov; L. Stutte; M. Svoiski; N. K. Terentyev; G. P. Thomas; L. N. Uvarov; A. N. Vasiliev; D. V. Vavilov; V. S. Verebryusov; V. A. Victorov; V. E. Vishnyakov; A. A. Vorobyov; K. Vorwalter; J. You; Zhao Wenheng; Zheng Shuchen; R. Zukanovich-Funchal

2002-01-01

122

Doubly virtual Compton scattering and the beam normal spin asymmetry  

Microsoft Academic Search

We construct an invariant basis for Compton scattering with two virtual photons (VVCS). The basis tensors are chosen to be gauge invariant and orthogonal to each other. The properties of the corresponding 18 invariant amplitudes are studied in detail. We consider the special case of elastic VVCS with the virtualities of the initial and final photons equal. The invariant basis

Mikhail Gorchtein; Mikhail

2006-01-01

123

Multiple Compton Scattering as a Function of Detector Size  

NASA Astrophysics Data System (ADS)

As photons penetrate detector matter, various kinds of interactions take place. One important kind is Compton scattering, a process by which an incoming photon inelastically collides with an electron thus resulting in a photon with a lower energy. This less energetic photon may escape the detector, or may continue its propagation through the detector matter and undergo more Compton scattering events before escaping. In the output spectrum, the region of multiple scattered photons (MSC) is distinct from those of single scattered photons (Compton continuum) and photoelectric absorption (photopeak). Such distinction is qualitatively discussed in the literature without quantitative treatment. Hence, the goal of this study is to gain quantitative insight on MSC. Specifically, this study aims to investigate the behavior of MSC as a function of detector size. A simulation code is prepared using the Geant toolkit. Results of the simulation reveal a decrease in the spectral MCS region with increase of detector size. Moreover, the results show an increase in the average number of pre-escape multiple Compton collisions undergone by photons with the increase of detector size. These findings agree with theory.

Alrefae, Tareq

2013-04-01

124

MULECS: The Monash University Low Energy Compton scattering package  

Microsoft Academic Search

Monte Carlo based radiation transport modelling is a useful tool in evaluating the interaction and effect of radiation in a defined environment. The process of simulating Compton scattering is of interest in a large number of different fields. Of the range of available Monte Carlo radiation transport programs, Geant4, one of the most popular, integrated the effects of Doppler broadening

J. M. C. Brown; M. R. Dimmock; J. E. Gillam; D. M. Paganin

2011-01-01

125

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

126

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

127

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 1.4×108s-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

128

An electromagnetic calorimeter for the JLab real compton scattering experiment  

SciTech Connect

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%/View the MathML source. Features of both the detector design and its performance in the high luminosity environment during the experiment are presented.

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

2011-07-01

129

Generalized Parton Distributions from Deep Virtual Compton Scattering at CLAS  

SciTech Connect

We have analyzed the beam spin asymmetry and the longitudinally polarized target spin asymmetry of the Deep Virtual Compton Scattering process, recently measured by the Jefferson Lab CLAS collaboration. Our aim is to extract information about the Generalized Parton Distributions of the proton. By fitting these data, in a largely model-independent procedure, we are able to extract numerical values for the two Compton Form Factors $H_{Im}$ and $\\tilde{H}_{Im}$ with uncertainties, in average, of the order of 30%.

M. Guidal

2010-05-01

130

An analytical image reconstruction algorithm to compensate for scattering angle broadening in Compton cameras.  

PubMed

Compton cameras have been developed for use in gamma-ray astronomy and nuclear medicine. Their defining merit is that they do not need collimators; however, on the demerit side, they need inversion procedures for image reconstruction, since a measured datum is proportional to the integration of incident gamma rays along a cone surface with the same Compton scattering angle. First, an iteration method was adopted for this task. Later, analytical methods were found under restricted conditions. Parra (2000 IEEE Trans. Nucl. Sci. 47 1543-50) deduced a purely analytical reconstruction algorithm for a complete set of scattering-projection data that include data at all the scattering angles. Tomitani and Hirasawa (2002 Phys. Med. Biol. 47 2129-45) found that by making a slight modification, Parra's algorithm could be extended to the scattering-projection data in limited scattering angles. However, their algorithm neglected the effects of practical problems that cause the degradation of spatial resolution. Sources of degradation were identified as noise in the energy signal of their front detector and the Doppler effect in the scattering process. In this paper, we first analyse the effects of these sources on the angular resolution of the scattering-projection data and then present a revised reconstruction algorithm in which these two factors are incorporated. Simulation studies on digital phantoms reveal that the algorithm can reconstruct images even when these two factors are included. PMID:12741498

Hirasawa, M; Tomitani, T

2003-04-21

131

Computations of Model Atmospheres with Account of Compton Scattering  

NASA Astrophysics Data System (ADS)

In this paper we formulate new method designed for calculation of hot LTE model stellar atmospheres in hydrostatic and radiative equilibrium, which takes into account Compton scattering on free electrons according to the diffusion approximation. The equation of transfer at each frequency includes both temperature corrections and noncoherent scattering terms. Full set of transfer equations and the closing equation of radiative equilibrium is organized in the form extending the Rybicki solution. The corresponding computer code ensures very rapid convergence of iterated model atmospheres. New computer code has been used to calculate series of pure H models in LTE for Teff=5 times 10^4 K, 7 times 10^4 K, and 1 times 10^5 K. Assumed surface gravities log g in a series are in the range between 7.0 and 6.0 -- 5.0 (cgs units). All test models are obtained with the Eddington approximation in the radiation transfer. This choice of parameters corresponds to the central stars of some planetary nebulae and subdwarf O stars. Model atmospheres clearly exhibit both the typical effects of noncoherent Compton scattering, ie the rise of temperature in the uppermost layers and the depression of monochromatic flux in X-ray part of the spectrum. While both effects are of minor significance at log g=7.0 or at the lowest Teff, they grow substantially at lower surface gravities or at Teff = 1 times 10^5 K. The impact of surface Compton heating on the Balmer line profiles and on the formation of the emission core in H_alpha is also demonstrated here. Computational results demonstrate the importance of Compton scattering of continuum radiation for the formation of strong spectral lines at low log g. Moreover, the rise of boundary T(tau) caused by comptonization should influence the formation of stellar wind in low gravity hot stars.

Madej, Jerzy

1994-04-01

132

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

133

From hard exclusive meson electroproduction to deeply virtual Compton scattering  

NASA Astrophysics Data System (ADS)

We systematically evaluate observables for hard exclusive electroproduction of real photons and compare them to experiment using a set of Generalized Parton Distributions (GPDs) whose parameters are constrained by Deeply Virtual Meson Production data, nucleon form factors and parton distributions. The Deeply Virtual Compton Scattering amplitudes are calculated to leading-twist accuracy and leading order in QCD perturbation theory while the leptonic tensor is treated exactly, without any approximation. This study constitutes a check of the universality of the GPDs. We summarize all relevant details on the parameterizations of the GPDs and describe its use in the handbag approach of the aforementioned hard scattering processes. We observe good agreement between predictions and measurements of deeply virtual Compton scattering on a wide kinematic range, including most data from H1, ZEUS, HERMES, Hall A and CLAS collaborations for unpolarized and polarized targets when available. We also give predictions relevant for future experiments at COMPASS and JLab after the 12 GeV upgrade.

Kroll, P.; Moutarde, H.; Sabatié, F.

2013-01-01

134

Electronic structure of CaCO?: a Compton scattering study.  

PubMed

In the present work, we have studied electron momentum density of CaCO? using a Compton scattering technique. The experiment has been performed using a 100 mCi (241)Am (59.54 keV) Compton spectrometer. The experimental data have been interpreted in terms of theoretical Compton profiles. To compute the theoretical momentum densities, energy bands and density of states, we have used linear combination of atomic orbitals method as embodied in CRYSTAL09 code. We have used local density approximation, generalized gradient approximation (GGA) and second order GGA (SOGGA) within the frame work of density functional theory. It is seen that the GGA gives a better agreement with the experimental data than other approximations. We have also discussed the energy bands and density of states of CaCO?. PMID:23208233

Mohammed, S F; Mohammad, F M; Sahariya, Jagrati; Mund, H S; Bhamu, K C; Ahuja, B L

2012-10-17

135

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

136

Analytic Expressions for the Angular Resolution of Compton Gamma-ray Detectors.  

National Technical Information Service (NTIS)

This paper describes the derivation of analytic expressions for the angular resolution of reconstructing gamma rays detected via Compton interactions. We consider two types of gamma-ray detectors: Compton-ring and electron-tracking devices. In Compton-rin...

D. M. Wright

2004-01-01

137

A Practical Review of the Kompaneets Equation and its Application to Compton Scattering  

SciTech Connect

In this study, we explore both inverse Compton and Compton scattering processes using the Chang and Cooper scheme to form a deterministic solution of the Kompaneets equation. We examine the individual terms of the Kompaneets equation and illustrate their effect on the equilibrium solution. We use two examples (a Gaussian line profile and a Planck profile) to illustrate the advective and diffusive properties of the Kompaneets operator. We also explore both inverse Compton scattering and Compton scattering, and discuss and illustrate the Bose-Einstein condensation feature of the Compton scattering spectrum.

D.G. Shirk

2006-05-15

138

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

139

A novel method for non-destructive Compton scatter imaging based on the genetic algorithm  

NASA Astrophysics Data System (ADS)

Compton scattering tomography is widely used in numerous applications such as biomedical imaging, nondestructive industrial testing and environmental survey, etc. This paper proposes the use of the genetic algorithm (GA), which utilizes bio-inspired mathematical models, to construct an image of the insides of a test object via the scattered photons, from a voxel within the object. A NaI(Tl) scintillation detector and a 185 MBq 137Cs gamma ray source were used in the experimental measurements. The obtained results show that the proposed GA based method performs well in constructing images of objects.

Ashrafi, Saleh; Jahanbakhsh, Okhtay; Alizadeh, Davood; Salehpour, Behrooz

2013-05-01

140

Charge localization in alcohol isomers studied by Compton scattering  

SciTech Connect

The isomers of small molecule alcohols propanol (PrOH) and butanol (BuOH) are studied by x-ray Compton scattering experiments with synchrotron radiation and density-functional theory calculations. The lineshape of the measured spectra, i.e., the Compton profile, is a momentum-space property, and its changes reflect changes in the electronic charge density between the isomers. Compared to the linear alcohols (n-PrOH and n-BuOH), the Compton profiles of the branched alcohols (iso-PrOH, iso-BuOH, sec-BuOH) are found to be narrower, which indicates a more delocalized charge for the latter. The calculations are performed for systems consisting of one to three monomer units and are found to reproduce reasonably the experimental spectral features. The influence of the basis set and exchange-correlation scheme is studied in more detail. The results provide new insight into the isomeric differences in small molecule alcohols and show that quantum chemical calculations can be increasingly tested against the x-ray Compton scattering data.

Hakala, M.; Nygaard, K.; Haemaelaeinen, K. [Department of Physics, University of Helsinki, P.O. Box 64, Helsinki FI-00014 (Finland); Vaara, J. [Department of Chemistry, Laboratory of Physical Chemistry, University of Helsinki, P.O. Box 55, Helsinki FI-00014 (Finland); Itou, M.; Sakurai, Y. [JASRI, SPring-8, 1-1-1, Kouto, Sayo-gun, Hyogo 679-5198 (Japan)

2009-01-21

141

The resonant inverse Compton scattering spectrum of an assembly of relativistic electrons in a varying magnetic field  

Microsoft Academic Search

Resonant inverse Compton scattering (RICS) of relativistic electrons in intense magnetic fields is an effective mechanism for producing gamma rays. On the basis of our preceding work, we derive the fundamental formula of the radiative spectrum of the collective RICS produced by a large assembly of relativistic electrons with a power-law energy spectrum moving outward along the magnetic axis of

Dang-Bo Liu; Le Chen; Jun-Han You; Shuang-Nan Zhang

2006-01-01

142

Compton-dragged Gamma-Ray Bursts Associated with Supernovae.  

PubMed

It is proposed that the gamma-ray photons that characterize the prompt emission of gamma-ray bursts are produced through the Compton-drag process, which is caused by the interaction of a relativistic fireball with a very dense soft photon bath. If gamma-ray bursts are indeed associated with supernovae, then the exploding star can provide enough soft photons for radiative drag to be effective. This model accounts for the basic properties of gamma-ray bursts, i.e., the overall energetics, the peak frequency of the spectrum, and the fast variability, with an efficiency that can exceed 50%. In this scenario, there is no need for particle acceleration in relativistic collisionless shocks. Furthermore, although the Poynting flux may be important in accelerating the outflow, no magnetic field is required in the gamma-ray production. The drag also naturally limits the relativistic expansion of the fireball to Gamma less, similar104. PMID:10615026

Lazzati; Ghisellini; Celotti; Rees

2000-01-20

143

On Timelike Compton Scattering at Medium and High Energies  

NASA Astrophysics Data System (ADS)

We emphasize the complementarity of timelike and spacelike studies of deep exclusive processes, taking as an example the case of timelike Compton scattering (TCS) i.e. the exclusive photoproduction of a lepton pair with large invariant mass, versus deeply virtual Compton scattering i.e. the exclusive leptoproduction of a real photon. Both amplitudes factorize with the same generalized parton distributions (GPDs) as their soft parts and coefficient functions which differ significantly at next to leading order in ? s . We also stress that data on TCS at very high energy should be available soon thanks to the study of ultraperipheral collisions at the LHC, opening a window on quark and gluon GPDs at very small skewness.

Pire, B.; Szymanowski, L.; Wagner, J.

2012-07-01

144

Low-Intensity Nonlinear Spectral Effects in Compton Scattering  

SciTech Connect

Nonlinear effects are known to occur in Compton scattering light sources, when the laser normalized 4-potential, A = e{radical}-A{sub {mu}}A{sup {mu}}/m{sub 0}c 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, {Delta}{phi}{sup -1}, is sufficiently small to satisfy A{sup 2} {Delta}{phi} {approx_equal} 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, F V; Albert, F; Siders, C W; Barty, C P

2010-02-23

145

Compton scattering in a unitary approach with causality constraints  

NASA Astrophysics Data System (ADS)

Pion-loop corrections for Compton scattering are calculated in a novel approach based on the use of dispersion relations in a formalism obeying unitarity. The basic framework is presented, including an application to Compton scattering. In the approach the effects of the non-pole contribution arising from pion dressing are expressed in terms of (half-off-shell) form factors and the nucleon self-energy. These quantities are constructed through the application of dispersion integrals to the pole contribution of loop diagrams, the same as those included in the calculation of the amplitudes through a K-matrix formalism. The prescription of minimal substitution is used to restore gauge invariance. The resulting relativistic-covariant model combines constraints from unitarity, causality, and crossing symmetry.

Kondratyuk, S.; Scholten, O.

2000-09-01

146

Basic performance of unitized Compton scattering type polarimeter.  

NASA Astrophysics Data System (ADS)

The authors have been developing a Compton scattering type polarimeter which consists of nine unit counters to detect the polarization of hard X-rays from stellar objects such as the Crab Nebula. The performance of the planned polarimeter was estimated by computer simulations. The results showed that the polarimeter can detect the polarization of hard X-rays from the Crab Nebula at a MDP (minimum detectable polarization) of 14.0% with a 3-hour balloon observation.

Tomita, H.; Sano, S.; Sakurai, H.; Noma, M.; Gunji, S.; Takase, E.

1996-06-01

147

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 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

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

2005-01-01

148

Basic performance of unitized Compton scattering type polarimeter  

Microsoft Academic Search

We have been developing a Compton scattering type polarimeter which consists of nine unit counters to detect the polarization of hard X-rays from stellar objects such as the Crab Nebula. One unit counter which consists of one plastic scintillator (7×7×5 cm3 ) and four phoswich counters (6.7×1.1×32.2 cm3 ) made of NaI(Tl)+CsI(Na) was constructed and its performance was measured in

H. Tomita; S. Sano; H. Sakurai; M. Noma; S. Gunji; E. Takase

1995-01-01

149

Basic performance of unitized Compton scattering type polarimeter  

Microsoft Academic Search

We have been developing a Compton scattering type polarimeter which consists of nine unit counters to detect the polarization of hard X-rays from stellar objects such as the Crab Nebula. We constructed one unit counter which consists of one plastic scintillator (7×7×5 cm3) and four phoswich scintillators (6.7×1.1×32.2 cm3) made of NaI(Tl)+CsI(Na). The characteristics of the unit counter were measured

H. Tomita; S. Sano; H. Sakurai; M. Noma; S. Gunji; E. Takase

1996-01-01

150

Direct Observation of Tunneling in KDP using Neutron Compton Scattering  

Microsoft Academic Search

Neutron Compton scattering measurements presented here of the momentum distribution of hydrogen in KH2PO4 just above and well below the ferroelectric transition temperature are sufficiently sensi­tive to show clearly that the proton is coherent over both sites in the high temperature phase, a result that invalidates the commonly accepted order-disorder picture of the transition. The Born-Oppenheimer potential for the hydrogen,

G. F. Reiter; J. Mayers; P. Platzman

2002-01-01

151

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

152

Measurement of Deeply Virtual Compton Scattering Beam-Spin Asymmetries  

Microsoft Academic Search

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 (xB from 0.11 to 0.58, Q2 from 1 to 4.8GeV2, -t from 0.09

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

2008-01-01

153

High-Energy Scaling of Compton Scattering Sources  

NASA Astrophysics Data System (ADS)

No monochromatic, high-brightness, tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard x-ray sources include: nuclear resonance fluorescence spectroscopy, time-resolved positron annihilation spectroscopy, and MeV flash radiography. The peak brightness of Compton scattering light sources is derived for head-on collisions and found to scale with the electron beam brightness and the drive laser pulse energy. This ?^2-scaling shows that for low emittance electron beams (1 nC, 1 mm.mrad, < 1 ps, > 100 MeV), and tabletop laser systems (1-10 J, 5 ps) the x-ray peak brightness can exceed 10^23 photons / mm^2 x mrad^2 x s x 0.1% bandwidth near 1 MeV; this is confirmed by 3D codes that have been benchmarked against Compton scattering experiments performed at LLNL. Important nonlinear effects, including spectral broadening, are also taken into account in our analysis; they show that there is an optimum laser pulse duration in this geometry, of the order of a few picoseconds, in sharp contrast with the initial approach to laser-driven Compton scattering sources where femtosecond laser systems were thought to be mandatory. This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.

Hartemann, Frederic

2005-10-01

154

Compton scattering off elementary spin (3/2) particles  

SciTech Connect

We calculate Compton scattering off an elementary spin (3/2) particle in a recently proposed framework for the description of high spin fields based on the projection onto eigensubspaces of the Casimir operators of the Poincare group. We also calculate this process in the conventional Rarita-Schwinger formalism. Both formalisms yield the correct Thomson limit but the predictions for the angular distribution and total cross section differ beyond this point. We point out that the average squared amplitudes in the forward direction for Compton scattering off targets with spin s=0, (1/2), 1 are energy independent and have the common value 4e{sup 4}. As a consequence, in the rest frame of the particle the differential cross section for Compton scattering in the forward direction is energy independent and coincides with the classical squared radius. We show that these properties are also satisfied by a spin (3/2) target in the Poincare projector formalism but not by the Rarita-Schwinger spin (3/2) particle.

Delgado-Acosta, E. G.; Napsuciale, M. [Departamento de Fisica, Division de Ciencias e Ingenierias, Universidad de Guanajuato, Campus Leon, Lomas del Bosque 103, Fraccionamiento Lomas del Campestre, 37150, Leon, Guanajuato (Mexico)

2009-09-01

155

Collisionless Landau damping and stimulated compton scattering  

Microsoft Academic Search

Stimulated scattering by free electrons is first studied within a quantum model due to Schroedinger and subsequently within a classical ``hydrodynamical'' picture. In the latter case, it can be shown that a method initially introduced by Landau to study the damping of electronic vibrations in plasmas is well suited to this problem and provides a precise analysis of the experimental

Guy Mayer

1977-01-01

156

Cooling Rates for Relativistic Electrons Undergoing Compton Scattering in Strong Magnetic Fields  

NASA Astrophysics Data System (ADS)

For inner magnetospheric models of hard X-ray and gamma-ray emission in high-field pulsars and magnetars, resonant Compton upscattering is anticipated to be the most efficient process for generating continuum radiation. This is in part due to the proximity of a hot soft photon bath from the stellar surface to putative radiation dissipation regions in the inner magnetosphere. Moreover, because the scattering process becomes resonant at the cyclotron frequency, the effective cross section exceeds the classical Thomson value by over two orders of magnitude, thereby enhancing the efficiency of continuum production and the cooling of relativistic electrons. This paper presents computations of the electron cooling rates for this process, which are needed for resonant Compton models of non-thermal radiation from such highly magnetized pulsars. The computed rates extend previous calculations of magnetic Thomson cooling to the domain of relativistic quantum effects, sampled near and above the quantum critical magnetic field of 44.13 TG. This is the first exposition of fully relativistic, quantum magnetic Compton cooling rates for electrons, and it employs both the traditional Johnson & Lippmann cross section and a newer Sokolov & Ternov (ST) formulation of Compton scattering in strong magnetic fields. Such ST formalism is formally correct for treating spin-dependent effects that are important in the cyclotron resonance and has not been addressed before in the context of cooling by Compton scattering. The QED effects are observed to profoundly lower the rates below extrapolations of the familiar magnetic Thomson results, as expected, when recoil and Klein-Nishina reductions become important.

Baring, Matthew G.; Wadiasingh, Zorawar; Gonthier, Peter L.

2011-05-01

157

Optimization of the gamma spectrometry system at SAL with the use of large NaI(Tl) annulus in the anticoincidence mode for compton scattered radiation suppression.  

National Technical Information Service (NTIS)

A gamma-ray spectrometer designed for the simultaneous acquisition of normal, coincidence and anticoincidence spectra was extensively tested. The spectrometer consists of 3 detectors: a HPGe coaxial of 42% efficiency, NaI(Tl) annulus 254 mm length and 254...

J. Kierzek J. Parus

1997-01-01

158

Gamma-ray bursts from synchrotron self-Compton emission  

Microsoft Academic Search

The emission mechanism of gamma-ray bursts (GRBs) is still a matter of debate. The standard synchrotron energy spectrum of cooling electrons FE~E-1\\/2 is much too soft to account for the majority of the observed spectral slopes. An alternative in the form of quasi-thermal Comptonization in a high-compactness source has difficulties in reproducing the peak of the observed photon distribution below

Boris E. Stern; Juri Poutanen

2004-01-01

159

Gamma-ray Compton profiles of copper and nickel  

Microsoft Academic Search

Te123m 160-keV gamma rays were used to measure the Compton profiles of fcc copper and nickel single crystals in the [100], [110], and [111] directions. The differences in the profiles in the various directions are only on the order of 1% but still clearly show the presence of d-type bonds in the [110] directions. Comparison of copper and nickel shows

P. Eisenberger; W. A. Reed

1974-01-01

160

Beam-charge azimuthal asymmetry and deeply virtual Compton scattering  

SciTech Connect

The first observation of an azimuthal cross section asymmetry with respect to the charge of the incoming lepton beam is reported from a study of hard exclusive electroproduction of real photons. The data have been accumulated by the HERMES experiment at DESY, in which the HERA 27.6 GeV electron or positron beam scattered off an unpolarized hydrogen gas target. The observed asymmetry is attributed to the interference between the Bethe-Heitler process and the deeply virtual Compton scattering (DVCS) process. The interference term is sensitive to DVCS amplitudes, which provide the most direct access to generalized parton distributions.

Airapetian, A.; Deconinck, W.; Lorenzon, W. [Randall Laboratory of Physics, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States); Akopov, N.; Akopov, Z.; Avakian, R.; Avetissian, A.; Elbakian, G.; Gharibyan, V.; Marukyan, H.; Rostomyan, A.; Taroian, S. [Yerevan Physics Institute, 375036 Yerevan (Armenia); Amarian, M. [DESY, 15738 Zeuthen (Germany); Yerevan Physics Institute, 375036 Yerevan (Armenia); Andrus, A.; Bailey, P.; Bouwhuis, M.; Linden-Levy, L. A.; Makins, N. C. R.; Rubin, J. [Department of Physics, University of Illinois, Urbana, Illinois 61801-3080 (United States); Aschenauer, E. C. [DESY, 15738 Zeuthen (Germany)] (and others)

2007-01-01

161

Compton scattering from positronium and validity of the impulse approximation  

SciTech Connect

The cross sections for Compton scattering from positronium are calculated in the range from 1 to 100 keV incident photon energy. The calculations are based on the A{sup 2} term of the photon-electron or photon-positron interaction. Unlike in hydrogen, the scattering occurs from two centers and the interference effect plays an important role for energies below 8 keV. Because of the interference, the criterion for validity of the impulse approximation for positronium is more restrictive compared to that for hydrogen.

Kaliman, Z.; Pisk, K.; Pratt, R. H. [Department of Physics, University of Rijeka, Rijeka (Croatia); Rudjer Boskovic Institute, P. O. Box 180, Zagreb (Croatia) and University of Dubrovnik, Dubrovnik (Croatia); Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States)

2011-05-15

162

Deeply virtual Compton scattering via color dipoles: Nonperturbative effects  

SciTech Connect

We study the deeply virtual Compton scattering amplitude within the color dipole approach. The light-cone wave function of a real photon is evaluated in the instanton vacuum model. Our parameter-free calculations are able to describe H1 data, both the absolute values and the t dependences, at medium-high values of Q{sup 2}. The Q{sup 2} dependence is found to be sensitive to the choice of the phenomenological cross section fitted to deep-inelastic scattering data.

Kopeliovich, B. Z.; Schmidt, Ivan; Siddikov, M. [Departamento de Fisica y Centro de Estudios Subatomicos, Universidad Tecnica Federico Santa Maria, Casilla 110-V, Avda. Espana 1680, Valparaiso (Chile)

2009-02-01

163

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

164

Compton scattering from nuclei and photo-absorption sum rules  

NASA Astrophysics Data System (ADS)

We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new “constituent quark model” sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition, we extract the ?=0 pole contribution for both proton and nuclei. Using the modern high-energy proton data, we find that the ?=0 pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman.

Gorchtein, Mikhail; Hobbs, Timothy; Londergan, J. Timothy; Szczepaniak, Adam P.

2011-12-01

165

Compton recoil electron tracking with silicon strip detectors  

Microsoft Academic Search

The application of silicon strip detectors to Compton gamma ray astronomy telescopes is described. The silicon Compton recoil telescope tracks Compton recoil electrons in silicon strip converters to provide an unique direction for Compton scattered gamma rays above 1 MeV. With strip detectors of modest positional and energy resolutions, of 1 mm FWHM and 3% at 662 keV, respectively, true

T. J. O'Neill; F. Ait-Ouamer; I. Schwartz; O. T. Tumer; R. S. White; A. D. Zych

1992-01-01

166

Compton suppression gamma-counting: The effect of count rate  

USGS Publications Warehouse

Past research has shown that anti-coincidence shielded Ge(Li) spectrometers enhanced the signal-to-background ratios for gamma-photopeaks, which are situated on high Compton backgrounds. Ordinarily, an anti- or non-coincidence spectrum (A) and a coincidence spectrum (C) are collected simultaneously with these systems. To be useful in neutron activation analysis (NAA), the fractions of the photopeak counts routed to the two spectra must be constant from sample to sample to variations must be corrected quantitatively. Most Compton suppression counting has been done at low count rate, but in NAA applications, count rates may be much higher. To operate over the wider dynamic range, the effect of count rate on the ratio of the photopeak counts in the two spectra (A/C) was studied. It was found that as the count rate increases, A/C decreases for gammas not coincident with other gammas from the same decay. For gammas coincident with other gammas, A/C increases to a maximum and then decreases. These results suggest that calibration curves are required to correct photopeak areas so quantitative data can be obtained at higher count rates. ?? 1984.

Millard, Jr. , H. T.

1984-01-01

167

Compton Scattering of Fe K? Lines from Accreting White Dwarfs  

NASA Astrophysics Data System (ADS)

Compton scattering in the bulk accretion flow of the accretion column in magnetic cataclysmic variables can significantly shift photon energies in the X-ray emission lines resulting from accretion shocks. In particular, Compton recoil can potentially broaden the 6.7 and 6.97keV Fe K? emission lines produced in the post-shock region, and contaminate the fluorescent 6.4keV neutral Fe K? line reflected off the white dwarf surface. We present nonlinear Monte Carlo simulations demonstrating these effects, and we discuss the interpretation of observed Fe K? linewidths in magnetic cataclysmic variables in light of these new results. The implications for other accreting compact objects are also discussed.

Kuncic, Zdenka; Wu, Kinwah; Cullen, Jason G.

168

Angular Distribution of Fluorescent L X-Rays and Compton-Scattering Photons  

Microsoft Academic Search

The angular distribution of fluorescent L X-rays and Compton-scattering photons was investigated by measuring differential cross sections for high–atomic-number elements. The measurements were taken simultaneously for L X-ray and Compton-scattering photons using Am-241 radioisotope as photon sources and a Si(Li) detector in various emission angles. The measurements confirm well-known angular dependency of the Compton-scattering differential cross section. L X-ray angular

I. Han; L. Demir

2011-01-01

169

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

2013-06-25

170

Cosmic Gamma-ray from Inverse Compton Process in Unstable Dark Matter Scenario  

SciTech Connect

Motivated by the PAMELA anomaly in the fluxes of cosmic-ray e{sup +} and e{sup -}, we study the cosmic gamma-ray induced by the inverse Compton (IC) scattering process in unstable dark matter scenario assuming that the anomaly is due to the e{sup +}- emission by the decay of dark matter. We calculate the fluxes of IC-induced gamma-ray produced in our Galaxy and that from cosmological distance, and show that both of them are significant. We discuss a possibility that large dark matter mass over TeV scale might be constrained by the gamma-ray observation by Fermi Gamma-ray Space Telescope.

Ishiwata, Koji; Moroi, Takeo [Department of Physics, Tohoku University, Sendai 980-8578 (Japan); Matsumoto, Shigeki [Department of Physics, University of Toyama, Toyama 930-8555 (Japan)

2010-03-26

171

Noncommutative QED and $\\\\gamma\\\\gamma$ scattering  

Microsoft Academic Search

We study $\\\\gamma\\\\gamma$ scattering in noncommutative QED (NCQED) where the gauge field has Yang-Mills type coupling, giving new contributions to the scattering process and making it possible for it to occur at tree level. The process takes place at one loop level in the Standard Model (SM) and could be an important signal for physics beyond SM. But it is

Namit Mahajan

2001-01-01

172

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

173

High-Energy Scaling of Compton Scattering Light Sources  

Microsoft Academic Search

Summary form only given. No monochromatic (Deltaomega\\/omega), high-brightness [>1020 photons\\/(mm2timesmrad2timesstimes0.1% bandwidth)], tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard X-ray and g-ray sources include: nuclear resonance fluorescence spectroscopy, time-resolved positron annihilation spectroscopy, and MeV flash radiography. In this paper, the peak brightness of Compton scattering light sources is derived for head-on

F. V. Hartemann; D. J. Gibson; S. G. Anderson; A. M. Tremaine; P. T. Springer; A. J. Wootton; E. P. Hartouni; C. P. J. Barty

2005-01-01

174

MICROBUNCH TEMPORAL DIAGNOSTIC BY COMPTON SCATTERING IN INTERFERING LASER BEAMS.  

SciTech Connect

The exact solution of the classical nonlinear equation of motion for a relativistic electron in the field of two electromagnetic (EM) waves is obtained. For the particular case of the linearly polarized standing EM wave in the planar optical cavity, the intensity of the nonlinear Compton scattering, the time of flight, and the momentum variation after the relativistic electron passes along the cavity axis are calculated in weak and strong field limits. The extent of these effects depends on the initial phase of the EM wave when the electron enters the cavity. This can be used for the production, diagnosis, and acceleration of relativistic electron (positron) microbunches.

AMATUNI,A.TS.; POGORELSKY,I.V.

1998-07-06

175

The equivalence of inverse Compton scattering and the undulator concept  

SciTech Connect

Inverse Compton scattering is a method to produce very high frequency photon beam. However, the production mechanism can also be viewed as a undulator emission. This is because the electron sees electric and magnetic fields of the incident laser beam and is driven into transverse oscillatory motion in exactly the same way when the electron passes through a undulator consisting of alternating magnetic field. This note gives a detailed examination of the similarity about the two views. Equivalent undulator parameters are derived for the incident laser beam, as well as the differential cross section of photon emission.

Ng, K.Y,; /Fermilab

2009-08-01

176

Microbunch temporal diagnostic by Compton scattering in interfering laser beams  

SciTech Connect

The exact solution of the classical nonlinear equation of motion for a relativistic electron in the field of two electromagnetic (EM) waves is obtained. For the particular case of the linearly polarized standing EM wave in the planar optical cavity, the intensity of the nonlinear Compton scattering, the time of flight, and the momentum variation after the relativistic electron passes along the cavity axis are calculated in weak and strong field limits. The extent of these effects depends on the initial phase of the EM wave when the electron enters the cavity. This can be used for the production, diagnosis, and acceleration of relativistic electron (positron) microbunches.

Amatuni, A. Ts.; Pogorelsky, I. V. [Yerevan Physics Institute, Alikhanian Brother's St. 2, Yerevan 375036 (Armenia); Accelerator Test Facility, BNL, Upton, New York 11973 (United States)

1999-07-12

177

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

178

Energy Calibration of Gamma Spectra in Plastic Scintillators using Compton Kinematics  

SciTech Connect

This paper describes a simple and practicable method for assigning energy values to gamma-ray pulse-height distributions measured with polyvinyl toluene based detectors. It is based upon the characteristic shape of the spectrum in the region of maximum energy deposition resulting from a single Compton scattering. The validity of this method is first demonstrated by applying it to a set of NaI(Tl) spectra, and comparing those results to the standard photo-peak method of calibrating the same spectra. The method is then applied to a set of polyvinyl toluene derived spectra.

Siciliano, Edward R.; Ely, James H.; Kouzes, Richard T.; Schweppe, John E.; Strachan, Denis M.; Yokuda, Satoru T.

2008-09-01

179

Virtual Compton Scattering at low energy and the generalized polarizabilities of the nucleon  

SciTech Connect

Virtual Compton Scattering (VCS) {gamma}*p {yields} {gamma}p at low CM energy gives access to the Generalized Polarizabilities of the nucleon. These observables generalize the concept of electromagnetic polarizabilities to the case of a virtual photon. Dedicated VCS experiments have been performed at MAMI, Jefferson Lab and MIT-Bates. The experimental status is reviewed, including analysis methods and physics results. The measurement of absolute (ep {yields} ep{gamma}) cross sections allows the extraction of the two unpolarized VCS structure functions P{sub LL}-P{sub TT}/{epsilon} and P{sub LT}, which are combinations of the Generalized Polarizabilities of the proton. Future prospects in the field of VCS at low energy are also presented.

Helene Fonvieille

2003-05-01

180

Polaritonic pulse and coherent X- and gamma rays from Compton (Thomson) backscattering  

SciTech Connect

The formation of polariton wave-packets created by high-intensity laser beams focused in plasmas is analyzed, and the velocity, energy, size, structure, stability, and electron content of such polaritonic pulses are characterized. It is shown that polaritonic pulses may transport trapped electrons with appreciable energies, provided the medium behaves as a rarefied classical plasma. The relativistic electron energy is related to the polariton group velocity, which is close to the velocity of light in this case. The plasma pulse is polarized, and the electron number in the pulse is estimated as being proportional to the square root of the laser intensity and the 3/2-power of the pulse size. It is shown that Compton (Thomson) backscattering by such polaritonic pulses of electrons may produce coherent X- and gamma rays, as a consequence of the quasirigidity of the electrons inside the polaritonic pulses and their relatively large number. The classical results of the Compton scattering are re-examined in this context, the energy of the scattered photons and their cross-section are analyzed, especially for backscattering, the great enhancement of the scattered flux of X- or gamma rays due to the coherence effect is highlighted and numerical estimates are given for some typical situations.

Apostol, M. [Department of Theoretical Physics, Institute of Atomic Physics, P.O. Box MG-35, Magurele-Bucharest MG-6 (Romania); Ganciu, M. [Laboratory of Plasma Physics, Institute of Lasers, Plasma and Radiation, P.O. Box MG-35, Magurele-Bucharest MG-6 (Romania)

2011-01-01

181

Joint refinement of a local wave-function model from Compton and Bragg scattering data  

SciTech Connect

The first joint refinement of a local wave-function model from diffraction and Compton scattering data is reported. The proposed method suits particularly well the case of insulators. Crystalline magnesium oxide, for which both accurate directional Compton profiles and low-order structure factors are available, is chosen as a test case. In particular, it is shown that Compton scattering provides a wealth of additional information to the structure factors in the case of a chemical bond investigation.

Gillet, J.-M.; Becker, P. J.; Cortona, P.

2001-06-15

182

Calibration and performance of the UCR double Compton gamma ray telescope  

SciTech Connect

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({ital Tl}) bars. The telescope is sensitive to celestial gamma-rays from 1 to 30 MeV. The data were collected on Feb. 14, 1988 prior to the 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 a {sup 24}Na 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.

Ait-Ouamer, F.; Kerrick, A.D.; Sarmouk, A.; O'Neill, T.J.; Sweeney, W.E.; Tumer, O.T.; Zych, A.D.; White, R.S. (California Univ., Riverside, CA (USA). Inst. of Geophysics and Planetary Physics)

1990-04-01

183

The nuclear compton telescope: A balloon-borne soft gamma-ray spectrometer, polarimeter, and imager  

Microsoft Academic Search

Our collaboration has begun the design and development of a prototype high resolution Compton telescope utilizing 3-D imaging germanium detectors. The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-15 MeV) telescope designed to study astrophysical sources of nuclear line emission and polarization. NCT is a prototype design for the Advanced Compton Telescope, to study gamma-ray radiation with very

S. E. Boggs; P. Jean; R. P. Lin; D. M. Smith; P. von Ballmoos; N. W. Madden; P. N. Luke; M. Amman; M. T. Burks; E. L. Hull; W. Craig; K. Ziock

2001-01-01

184

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

185

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

186

Compton Scattering and Photo-absorption Sum Rules on Nuclei  

NASA Astrophysics Data System (ADS)

We revisit the photo-absorption sum rule for real Compton scattering from the proton and from nuclear targets. In analogy with the Thomas-Reiche-Kuhn sum rule appropriate at low energies, we propose a new ``constituent quark model'' sum rule that relates the integrated strength of hadronic resonances to the scattering amplitude on constituent quarks. We study the constituent quark model sum rule for several nuclear targets. In addition we extract the J=0 pole contribution for both proton and nuclei. Using the modern high energy proton data we find that the J=0 pole contribution differs significantly from the Thomson term, in contrast with the original findings by Damashek and Gilman. We discuss phenomenological implications of this new result.

Gorshteyn, Mikhail; Hobbs, Timothy; Londergan, J. Timothy; Szczepaniak, Adam P.

2012-03-01

187

A Detailed Monte Carlo Study of Multiple Scattering Contamination in Compton Tomography at 90 degrees.  

PubMed

A low dose technique has been recently proposed for tomographic studies of the lung, which makes use of a gamma camera to detect 90 degrees Compton-scattered photons from external planar gamma source. In this paper, we present a detailed Monte Carlo study of this technique. A 20 x 20 x 20 cm3 water phantom was simulated as a target and a large gamma camera equipped with an imaging collimator as a detector. The multiple scattering contamination of the single scattered signal was studied as a function of the source-detector geometry and of the incident energy in the range 100-500 keV. The multiple to single scatter ratio has an approximate 1/E0.7 dependence and increases almost linearly with the phantom depth and the transversal thickness at 90 degrees . Simulation has been also performed with a 16 x 16 x 10 cm3 sawdust phantom of 0.3 g/cm3 density; the Monte Carlo results agree to within a few percent with experimental data. PMID:18238268

Del Guerra, A; Bellazzini, R; Tonelli, G; Venturi, R; Nelson, W R

1982-01-01

188

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

189

High-energy scaling of Compton scattering light sources  

NASA Astrophysics Data System (ADS)

No monochromatic (??x/?x<1%), high peak brightness [>1020photons/(mm2×mrad2×s×0.1%bandwidth)], tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard x-ray and ?-ray sources include the following: nuclear resonance fluorescence spectroscopy and isotopic imaging, time-resolved positron annihilation spectroscopy, and MeV flash radiography. In this paper, the peak brightness of Compton scattering light sources is derived for head-on collisions and found to scale quadratically with the normalized energy, ?; inversely with the electron beam duration, ??, and the square of its normalized emittance, ?; and linearly with the bunch charge, eNe, and the number of photons in the laser pulse, N?:B^x??2NeN?/?2??. This ?2 scaling shows that for low normalized emittance electron beams (1 nC, 1mm·mrad, <1ps, >100MeV), and tabletop laser systems (1-10J, 5 ps) the x-ray peak brightness can exceed 1023photons/(mm2×mrad2×s×0.1%bandwidth) near ??x=1MeV; this is confirmed by three-dimensional codes that have been benchmarked against Compton scattering experiments performed at Lawrence Livermore National Laboratory. The interaction geometry under consideration is head-on collisions, where the x-ray flash duration is shown to be equal to that of the electron bunch, and which produce the highest peak brightness for compressed electron beams. Important nonlinear effects, including spectral broadening, are also taken into account in our analysis; they show that there is an optimum laser pulse duration in this geometry, of the order of a few picoseconds, in sharp contrast with the initial approach to laser-driven Compton scattering sources where femtosecond laser systems were thought to be mandatory. The analytical expression for the peak on-axis brightness derived here is a powerful tool to efficiently explore the 12-dimensional parameter space corresponding to the phase spaces of both the electron and incident laser beams and to determine optimum conditions for producing high-brightness x rays.

Hartemann, F. V.; Brown, W. J.; Gibson, D. J.; Anderson, S. G.; Tremaine, A. M.; Springer, P. T.; Wootton, A. J.; Hartouni, E. P.; Barty, C. P. J.

2005-10-01

190

Evidence for a narrow N{sup *}(1685) resonance in quasifree Compton scattering on the neutron  

SciTech Connect

The study of quasifree Compton scattering on the neutron in the energy range of E{sub {gamma}}=0.75-1.5 GeV is presented. The data reveal a narrow peak at W{approx}1.685 GeV. This result, being considered in conjunction with the recent evidence for a narrow structure at W{approx}1.68 GeV in {eta} photoproduction on the neutron, suggests the existence of a nucleon resonance with unusual properties: a mass M{approx}1.685 GeV, a narrow width {Gamma}{<=}30 MeV, and the much stronger photoexcitation on the neutron than on the proton.

Kuznetsov, V. [Kyungpook National University, 702-701 Daegu (Korea, Republic of); Institute for Nuclear Research, 117312 Moscow (Russian Federation); Polyakov, M. V. [Institute fuer Theoretische Physik II, Ruhr-Universitaet Bochum, D-44780 Bochum (Germany); Petersburg Nuclear Physics Institute, Gatchina, 188300, St. Petersburg (Russian Federation); Bellini, V.; Giusa, A.; Mammoliti, F.; Randieri, C.; Russo, G.; Sperduto, M. L. [INFN-Sezione di Catania, via Santa Sofia 64, I-95123 Catania (Italy); Dipartimento di Fisica ed Astronomia, Universita di Catania, via Santa Sofia 64, I-95123 Catania (Italy); Boiko, T. [Belarussian State University, 220030 Minsk, Republic of Belarus (Belarus); Chebotaryov, S.; Dho, H.-S.; Kim, W.; Milman, E.; Ni, A. [Kyungpook National University, 702-701 Daegu (Korea, Republic of); Gervino, G. [Dipartamento di Fisica Sperimentale, Universita di Torino, via P. Giuria, I-00125 Torino (Italy); INFN-Sezione di Torino, I-10125 Torino (Italy); Ghio, F. [INFN--Sezione di Roma, piazzale Aldo Moro 2, I-00185 Roma (Italy); Instituto Superiore di Sanita, viale Regina Elena 299, I-00161 Roma (Italy); Kim, A. [Kyungpook National University, 702-701 Daegu (Korea, Republic of); Thomas Jefferson National Accelerator Facility, Jefferson Avenue, 23606 Virginia (United States); Perevalova, I. A.; Vall, A. N. [Physics Department, Irkutsk State University, Karl Marx str. 1, 664003 Irkutsk (Russian Federation); Sutera, C. M. [INFN--Sezione di Catania, via Santa Sofia 64, I-95123 Catania (Italy)

2011-02-15

191

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

192

Resumming soft and collinear contributions in deeply virtual Compton scattering  

NASA Astrophysics Data System (ADS)

We calculate the quark coefficient function T q ( x, ?) that enters the factorized amplitude for deeply virtual Compton scattering (DVCS) at all order in a soft and collinear gluon approximation, focusing on the leading double logarithmic behavior in ( x± ?), where x ± ? is the light cone momentum fraction of the incoming/outgoing quarks. We show that the dominant part of the known one loop result can be understood in an axial gauge as the result of a semi-eikonal approximation to the box diagram. We then derive an all order result for the leading contribution of the ladder diagrams and deduce a resummation formula valid in the vicinity of the boundaries of the regions defining the energy flows of the incoming/outcoming quarks, i.e. x = ± ?. The resummed series results in a simple closed expression.

Altinoluk, T.; Pire, B.; Szymanowski, L.; Wallon, S.

2012-10-01

193

Gauge invariance and Compton scattering from relativistic composite systems  

SciTech Connect

Using the Ward-Takahashi (W-T) identity and the Bethe-Salpeter (B-S) wave equation, we investigate the dynamical requirements imposed by electromagnetic gauge invariance on Compton scattering from relativistic composite system. The importance of off-shell rescattering in intermediate states, which is equivalent to final state interactions in inclusive processes, is clarified in the context of current conservation. It is shown that, if the nuclear force is nonlocal, there will be both two-photon interaction currents and rescattering contributions to terms involving one-photon interaction currents. We derive the two-body W-T identity for the two-photon interaction currents, and obtain explicit forms for the interaction current operators for three illustrative models of nuclear forces: (a) two-pion exchange forces with baryon resonances, (b) covariant separable forces, and (c) charged one-pion exchange.

Ito, H. [George Washington Univ., Washington, DC (United States). Center for Nuclear Studies; Gross, F. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)]|[College of William and Mary, Williamsburg, VA (United States). Dept. of Physics

1993-09-01

194

Deeply virtual Compton scattering from gauge/gravity duality  

NASA Astrophysics Data System (ADS)

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

Costa, Miguel S.; Djuri?, Marko

2013-04-01

195

Effective atomic number of composite materials for Compton effect in the gamma ray region 280-1115 keV.  

PubMed

In this paper, we report the effective atomic number, Z(eff), of composite materials for Compton effect in the gamma ray region 280-1115 keV based on the theoretically obtained Klein-Nishina scattering cross sections in the angular range 50-100° as well as experimentally measured differential incoherent (Compton) scattering cross sections of some composite materials at three scattering angles of 60°, 80°, and 100°. The Z(eff) values so obtained were found to be both angle and energy independent in the region of interest so that it could be concluded that it is possible to represent such composite materials by a mean atomic number in this region as suggested in earlier reports recently. PMID:20702099

Kumar, S Prasanna; Umesh, T K

2010-08-03

196

Characterization of scatterers for an active focal plane Compton polarimeter  

NASA Astrophysics Data System (ADS)

In this work we present an active Compton scattering polarimeter as a focal plane instrument able to extend the X-ray polarimetry towards hard X-rays.Other authors have already studied various instrument design by means of Monte Carlo simulations, in this work we will show for the first time the experimental measurements of "tagging efficiency" aimed to evaluate the polarimeter sensitivity as a function of energy. We performed a characterization of different scattering materials by measuring the tagging efficiency that was used as an input to the Monte Carlo simulation. Then we calculated the sensitivity to polarization of a design based on the laboratory set-up. Despite the geometry tested is not optimized for a realistic focal plane instrument, we demonstrated the feasibility of polarimetry with a low energy threshold of 20 keV. Moreover we evaluated a minimum detectable polarization of 10% for a 10 mCrab source in 100 ks between 20 and 80 keV in the focal plane of one multilayer optics module of NuSTAR. The configuration used consisted of a doped p-terphenyl scatterer 3 cm long and 0.7 cm of diameter coupled with a 0.2 cm thick LaBr3 absorber.

Fabiani, Sergio; Campana, Riccardo; Costa, Enrico; Del Monte, Ettore; Muleri, Fabio; Rubini, Alda; Soffitta, Paolo

2013-04-01

197

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

198

Experimental investigation of multiple scattering of 662 keV gamma rays in zinc at 90°  

NASA Astrophysics Data System (ADS)

Compton scattering investigations usually examine the case when 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 experiment is undertaken to study the intensity and energy distributions of 662 keV gamma rays multiply scattered from a zinc target of various thicknesses at a scattering angle of 90° with the scattered photons being detected by an HPGe gamma detector. We observe that with an increase in target thickness, the number of multiply scattered photons also increases and saturates at a particular value of the target thickness (saturation depth). This supports the work of Paramesh, L., Venkataramaih, L., Gopala, K., Sanjeevaih, H. [1983. Z-dependence of saturation depth for multiple scattering of 662 keV photons from thick samples. Nucl. Instrum. Methods 206, 327 230]. The double Compton scattered peak is also observed in the experimental spectra, with a position in agreement with the predictions of Fernandez, J.E. [1991. Compton and Rayleigh double scattering of unpolarized radiation. Phys. Rev. A44, 4232 4248] and Barnea, G., Dick. C.E., Ginzburg. A.E., Seltzer. S.M. [1995. A study of multiple scattering background in Compton scatter imaging. NDT E Int. 28. 155 162].

Singh, Gurvinderjit; Singh, Manpreet; Sandhu, B. S.; Singh, Bhajan

2007-05-01

199

Determination of 137Cs in Soil Samples by Low-Level Compton Suppression Gamma-Counting  

Microsoft Academic Search

We have used Compton suppression gamma ray counting to effectively measure 137Cs in undisturbed environmental samples weighing only one hundred grams of material. Our results have shown that Compton suppression is ideal in determining low levels (1–3 Bq\\/kg) of 137Cs in soil samples, while the Compton advantage is negligible for higher concentrations. Quality assurance and quality control experiments show that

F. Y. Iskander; S. Landsberger; S. D. Warren

2000-01-01

200

Gamma-ray pulsars: the Compton Observatory contribution to the study of isolated neutron stars  

Microsoft Academic Search

The four instruments on the Compton Gamma Ray Observatory have identified at least seven isolated neutron stars by their pulsed gamma-ray emission. For all of these, the gamma radiation represents the largest observable fraction of the spin-down luminosity, making the gamma rays important diagnostics of particle acceleration and interaction in the neutron star magnetospheres. Several other ``candidate'' pulsars have tentative

D. J. Thompson; A. K. Harding; W. Hermsen; M. P. Ulmer

1997-01-01

201

Gamma-ray pulsars: the Compton Observatory contribution to the study of isolated neutron stars  

Microsoft Academic Search

The four instruments on the Compton Gamma Ray Observatory have identified at least seven isolated neutron stars by their pulsed gamma-ray emission. For all of these, the gamma radiation represents the largest observable fraction of the spin-down luminosity, making the gamma rays important diagnostics of particle acceleration and interaction in the neutron star magnetospheres. Several other “candidate” pulsars have tentative

D. J. Thompson; A. K. Harding; W. Hermsen; M. P. Ulmer

1997-01-01

202

Lattice and beam parameters of compact intense x-ray sources based on Compton scattering  

NASA Astrophysics Data System (ADS)

The lattice of a laser-electron storage ring with a controlled momentum compaction factor dedicated to the generation of intense x rays under Compton scattering is described. In such a storage ring one can obtain large energy acceptance and keep the long-term stable motion of the electron beam with large energy spread. The intensity of x rays is stable due to the use of electron beam with steady-state parameters for Compton scattering. Parameters of the storage ring, electron beam, and x rays obtained by electron beam dynamics simulation involving both intrabeam and Compton scattering are presented.

Gladkikh, Peter

2005-05-01

203

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

Microsoft Academic Search

QED Compton scattering at HERA is proposed for a measurement of the proton structure function F 2 at low momentum transfers Q 2. It is shown that the analysis of inelastic QED Compton events allows the extension of present HERA structure function measurements to a kinematic domain, which up to now was only accessed in fixed target data. Preliminary results

V. Lendermann

2005-01-01

204

Inspecao de estruturas metalicas utilizando espalhamento de raios gama. (Inspection of metallic structures using gamma rays scattering).  

National Technical Information Service (NTIS)

The Compton scattering of gamma rays is used as an inspection technique in aluminium and steels test specimens. The results are presented in bidimensional images from the inspection plane. (C.G.C.). (Atomindex citation 22:060523)

M. J. Anjos R. T. Lopes

1990-01-01

205

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

206

A new transportable instrument for in-situ void and corrosion imaging in thick structural sections by three dimensional Compton scatter imaging  

Microsoft Academic Search

When X Gamma or other kinds of subatomic particle radiation are being used for NDE, measurements are almost always made on the primary beam after transmission through the object under test. Cases are described where better results, i.e., image quality or cost effectiveness can be obtained from measurements on scattered radiation rather than the primary beam. Compton imaging of high

B. Bridge

2000-01-01

207

Asymmetries and anisotropies in the Compton scattering from the hydrogen molecule  

SciTech Connect

The Compton energy loss spectra of atomic targets exhibits usually a specific asymmetry due to the postcollisional electrostatic interaction between the remaining ion and the ejected electron. This asymmetry, or Compton defect, also exists in the scattering by molecules or solids. The first attempt to describe the Compton defect for the hydrogen molecule is proposed here. The Compton energy loss spectra depends particularly on the relative orientation of the momentum transferred by the incident particle and the molecular axis. A comparison between the respective magnitudes of Compton profiles and Compton defects was one of the aims of this article. The results emphasize the particular interest of a simultaneous interpretation of both symmetrical and antisymmetrical contributions in the study of molecular or solid-state electronic structures. 16 refs., 5 figs.

Roeth, M.; Gasser, F.; Tavard, C. [Institut de Physique et Physico-chimie, Metz (France)

1995-03-05

208

Nucleon Polarizabilities from Low-Energy Compton Scattering  

NASA Astrophysics Data System (ADS)

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 undetermined parameters that are in one-to-one correspondence with the proton and neutron polarizabilities. These polarizabilities are extracted from fits to data on low-energy elastic photon scattering from hydrogen and deuterium. We find, in units of 10-4 fm^3, the following results for the proton and isoscalar polarizabilities [3]: ?p = (12.1 ± 1.1)^+0.5_-0.5 , ?p = (3.4 ± 1.1)^+0.1_-0.1 , ?N = (9.0 ± 1.5)^+3.6_-0.8 , ?N = (1.7 ± 1.5)^+1.4_-0.6 . [1] V. Bernard, N. Kaiser, and U.-G. Meißner, Int. J. Mod. Phys. E4, 193 (1995). [2] P.F. Bedaque and U. van Kolck, nucl-th/0203055; S.R. Beane, P.F. Bedaque, W.C. Haxton, D.R. Phillips, and M.J. Savage, Encyclopedia of Analytic QCD, At the Frontier of Particle Physics, vol. 1, 133-269, edited by M. Shifman (World Scientific). [3] S.R. Beane, M. Malheiro, J.A. McGovern, D.R. Phillips, U. van Kolck, nucl-th/0209002

McGovern, Judith A.

2003-04-01

209

Analysis of the data from Compton X-ray polarimeters which measure the azimuthal and polar scattering angles  

NASA Astrophysics Data System (ADS)

X-ray polarimetry has the potential to make key-contributions to our understanding of galactic compact objects like binary black hole systems and neutron stars, and extragalactic objects like active galactic nuclei, blazars, and Gamma-Ray Bursts. Furthermore, several particle astrophysics topics can be addressed including uniquely sensitive tests of Lorentz invariance. In the energy range from 10 keV to several MeV, Compton polarimeters achieve the best performance. In this paper we evaluate the benefit that comes from using the azimuthal and polar angles of the Compton scattered photons in the analysis, rather than using the azimuthal scattering angles alone. We study the case of an ideal Compton polarimeter and show that a Maximum Likelihood analysis which uses the two scattering angles lowers the Minimum Detectable Polarization (MDP) by ?20% compared to a standard analysis based on the azimuthal scattering angles alone. The accuracies with which the polarization fraction and the polarization direction can be measured improve by a similar amount. We conclude by discussing potential applications of Maximum Likelihood analysis methods for various polarimeter experiments.

Krawczynski, H.

2011-05-01

210

The limits of decision, detection, and determination in anti-Compton gamma-ray spectrometry  

Microsoft Academic Search

The improvement in the limits of decision, detection, and determination effected by anti-Compton gamma-ray spectrometry are considered. A simple procedure for the experimental determination is presented.

H. A. Das

1986-01-01

211

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

212

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

213

Measurement of Deeply Virtual Compton Scattering with a Polarized Proton Target  

SciTech Connect

The longitudinal target-spin asymmetry A{sub UL} for the exclusive electroproduction of high energy photons was measured for the first time in p(e,e'p/gamma). The data have been accumulated at Jefferson Lab with the CLAS spectrometer using 5.7 GeV electrons and a longitudinally polarized NH{sub 3} 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 sin(phi) moment is 0.252 +/- 0.042(stat) +/- 0.020(sys). 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-tilde.

S. Chen; H. Avakian; V. Burkert; P. Eugenio

2006-05-05

214

The Compton Effect and the Quantum Nature of the Scattering of Light by Electrons  

NASA Astrophysics Data System (ADS)

The Compton effect is commonly used to illustrate the quantized nature of light (Arthur H. Compton, Phys. Rev. 21), 483 (1923). It is not as well known that Compton's formula can be obtained by describing the scattering of classical light off a quantum electron wave (E. Schrödinger, Ann. Phys. (Leipzig) bf 28) 257 (1927). In this paper we review the different models that describe the scattering of light by electrons and find out how far the symmetry between the particle and the wave description of the projectile and the target will lead.

van Huele, Jean-François

1998-04-01

215

Measurement of trabecular bone mineral density using coherent and Compton scattered photons in vitro  

Microsoft Academic Search

A photon scattering method for measuring the trabecular bone mineral density (TBMD) in vitro is described. This method involves the measurement of the ratio of coherent to Compton 90 degrees scattered photons from ²⁴¹Am by using a narrow beam geometry with an intrinsic germanium detector. The feasibility of using smaller scattering angles for better counting efficiency and the associated problems

S. S. Ling; S. Rustgi; A. Karellas; J. D. Craven; J. S. Whiting; M. A. Greenfield; R. Stern

2009-01-01

216

Stimulated magneto-Compton scattering--A possible tunable far infrared and millimeter wave source  

Microsoft Academic Search

Several authors have considered the possibility of using stimulated Compton scattering as a source of tunable coherent far infrared radiation. For a finite photon-electron interaction region, it is known that the gain is small. It is shown that there is a significant increase in the photon-electron scattering cross section and hence in the gain when the scattering is performed resonantly

V. P. Sukhatme; P. A. Wolff

1974-01-01

217

X-ray generator based on Compton scattering  

NASA Astrophysics Data System (ADS)

Nowadays, the sources of the X-rays based on a storage ring with low beam energy and Compton scattering of intense laser beam are under development in several laboratories. In the paper the state-of-art in development and construction of cooperative project of a Kharkov advanced X-ray source NESTOR based on electron storage ring with beam energy 43 225 MeV and Nd:YAG laser are described. The layout of the facility is presented and latest results are described. The designed lattice includes 4 dipole magnets with combined focusing functions, 20 quadrupole magnets and 19 sextupoles with correcting components of magnetic field. At present, a set of quadrupole magnet is under manufacture and bending magnet reconstruction is going on. The main parameters of developed vacuum system providing residual gas pressure in the storage ring vacuum chamber up to 10-9 Torr are presented. The basic parameters of the X-ray source laser and injection systems are presented. The facility is going to be in operation from the middle of 2006 and generated X-ray flux is expected to be of about 1013 phot/s.

Androsov, V.; Agafonov, A.; Botman, J. I. M.; Bulyak, E.; Drebot, I.; Gladkikh, P.; Grevtsev, V.; Ivashchenko, V.; Karnaukhov, I.; Lapshin, V.; Lebedev, A.; Markov, V.; Mocheshnikov, N.; Mytsykov, A.; Peev, F.; Ryezayev, A.; Shcherbakov, A.; Skomorokhov, V.; Skyrda, V.; Tatchyn, R.; Telegin, Y.; Trotsenko, V.; Zelinsky, A.

2005-05-01

218

Low-energy K-shell Compton scattering  

SciTech Connect

We calculate the photon energy distribution and the total cross section for the Compton scattering on the K electrons for the case when the photon wave length is much smaller than the size of the K shell. We show that at the energies of the order of the binding energy I of the K electron most part of the spectrum is governed by the low-energy behavior. The total cross section has a local maximum at the energies (1.5-2)I, reaching the values of the order 1 barn. At higher photon energies the spectrum curves have two maxima, corresponding to low-energy ejected photons or electrons. The cross sections in the whole region are calculated. The actual calculations are carried out employing the nonrelativistic Coulomb functions, thus being valid for the single-electron atoms. However, the main features of the analysis are expected to be true for many-electron ions and neutral atoms. The results of the present analysis may be useful in calculations of the laser-induced and laser-assisted processes.

Drukarev, E. G. [Max-Planck Institute fuer Physik Komplexer Systeme, D-01187 Dresden (Germany); Mikhailov, A. I. [Petersburg Nuclear Physics Institute Gatchina, St. Petersburg, 188300 (Russian Federation); Mikhailov, I. A. [Petersburg Nuclear Physics Institute Gatchina, St. Petersburg, 188300 (Russian Federation); University of Central Florida 4000 Central Florida Boulevard, Orlando, Florida 32816 (United States)

2010-08-15

219

Compton continuum suppression by pulse shape analysis  

Microsoft Academic Search

The authors present experimental results on suppressing and flattening the Compton continuum by digital and analog pulse shape analysis. A doubling of the Cs-peak-to-Co-Compton ratio and a nice flattening of the Compton edges were achieved by pulse shape analysis in rejecting pulses from the peripheral regions of the Ge-detector, where the Compton scattering followed by the gamma escaping from the

B. Aspacher; G. J. Bamford; R. L. Coldwell; A. C. Rester

1992-01-01

220

Magnetic compton scattering using the elliptical multipole wiggler at sector 11-ID-B.  

SciTech Connect

Magnetic Compton scattering has been used to measure the momentum distribution of magnetic electrons in several materials. The polarization and frequency tunability of the elliptical multipole wiggler (EMW) makes it an ideal source for magnetic Compton scattering experiments. We performed the measurements using 50, 100 and 150 keV photons simultaneously. The EMW was operated at K{sub y}=14 (E{sub c}=32 keV) and K{sub x} between 0.6 and 1.03. The degree of circular polarization was about 80% or higher. The sample was mounted between the poles of an electromagnet in a field of 0.8 T. The majority of Compton scattering measurements were performed by switching the magnet polarity. Tests using an iron foil target gave a similar magnetic Compton profile by either switching the magnetic field or the photon helicity. A 9-element Ge solid state detector array was used for detection.

Montano, P. A.; Ruett, U.; Beno, M. A.; Jennings, G.; Kimball, C. W.; Materials Science Division; Univ. of Illinois at Chicago; Northern Illinois Univ.

2000-01-01

221

Atomic L-Shell Compton Profiles and Incoherent Scattering Factors.  

National Technical Information Service (NTIS)

Compton profiles are calculated for L-shell electrons within the Born approximation by use of nonrelativistic 'Exact' hydrogenic bound and continuum state wave functions. The wave functions are expressed in parabolic coordinates and the resulting matrix e...

B. J. Bloch L. B. Mendelsohn

1973-01-01

222

Compton recoil electron tracking with silicon strip detectors  

Microsoft Academic Search

The application of silicon strip detectors to Compton gamma-ray astronomy telescopes is described. The silicon Compton recoil telescope tracks Compton recoil electrons in silicon strip converters to provide a unique direction for Compton-scattered gamma rays above 1 MeV. With strip detectors of modest positional and energy resolutions of 1 mm full width at half maximum (FWHM) and 3% at 662

T. J. O'Neill; F. Ait-Ouamer; I. Schwartz; O. T. Tumer; R. S. White; A. D. Zych

1991-01-01

223

Virtual Compton scattering off a spinless target in AdS\\/QCD  

Microsoft Academic Search

We study the doubly virtual Compton scattering off a spinless target ?*P ? ?*P? within the Anti-de Sitter(AdS)\\/QCD formalism. We find that the general structure allowed by the Lorentz invariance and gauge\\u000a invariance of the Compton amplitude is not easily reproduced with the standard recipes of the AdS\\/QCD correspondence. In the\\u000a soft-photon regime, where the semi-classical approximation is supposed to

Cyrille Marquet; Claude Roiesnel; Samuel Wallon

2010-01-01

224

A sectored Ge-Compton polarimeter for parity assignments in photon scattering experiments  

Microsoft Academic Search

Parities of nuclear levels excited in photon scattering experiments can be determined by measurements of the linear polarization of the scattered photons. The needed theoretical formalism is summarized. A fourfold sectored single crystal Ge-Compton polarimeter, its operation and performances are described. The compact polarimeter has an outstanding coincidence efficiency ?coinc of about 25% and a good energy resolution of 2.2

B. Schlitt; U. Maier; H. Friedrichs; S. Albers; I. Bauske; P. von Brentano; R. D. Heil; R.-D. Herzberg; U. Kneissl; J. Margraf; H. H. Pitz; C. Wesselborg; A. Zilges

1994-01-01

225

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

226

Detection of high-energy gamma rays from quasar PKS 0528 + 134 by EGRET on the Compton Gamma Ray Observatory  

Microsoft Academic Search

The first several pointing directions of the Compton Gamma Ray Observatory, launched on 1991 April 5, were toward the Galactic anticenter. In addition to the known gamma-ray sources, Crab and Geminga, high-energy gamma-ray emission was observed from the quasar PKS 0528 + 134 by the Energetic Gamma Ray Experiment Telescope (EGRET). A redshift measurement, reported here, of 2.07 confirms the

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

1993-01-01

227

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

Microsoft Academic Search

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

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

1999-01-01

228

Guest Investigator Studies with the Compton Gamma Ray Observatory  

NASA Astrophysics Data System (ADS)

The cumulative all-sky survey by the Compton Gamma Ray Observatory (CGRO), composed of data acquired during the first three years of the mission, included a number of regions of very limited exposure. The most glaring deficiency in coverage was toward the region of the South Galactic Pole (SGP), which received significantly less exposure than other directions- by a factor of at least 2 to 3. Furthermore, nearly all of the SGP exposure was accumulated during the first year of the mission. Since blazars are known to be time-variable, and of unknown duty cycle, a pointing of the CCRO in that direction was considered highly desirable, and long overdue. In addition, data gathered from a pointing toward the SGP and its comparison with comprehensive data available for the North Galactic Pole would be extremely valuable to investigators studying the extragalactic diffuse emission. The reasons outlined above prompted our initiation of a Cycle 4 campaign to systematically search with EGRET and COMPTEL for gamma-ray emission from sources near the South Galactic Pole. The Cycle 4 SGP campaign consisted of tnvo 14-day observations separated in in time by approximately 10 months. The temporal separation of the observations was requested to allow a test for possible variations in the detected sources. Our primary targets were 38 FSRQs which lie within 30 degrees of the SGP, and which satisfy the basic criteria for candidate gamma-ray AGNs,flat-spectrum radio sources, many of which exhibit blazar-type properties). These targets were selected from the standard references, and from the available on-line databases (e.g., the NASA Extragalactic Database, NED), as the most promising AGN targets in the vicinity of the SGP. A 30 radius from the SGP was chosen as the boundary of our survey, since the selected targets would then fall within the most sensitive portion of the fields of view of EGRET and COMPTEL (i.e., within a 30 zenith angle), for a CGRO pointing directed exactly at the SGP. Our South Galactic Pole Survey yielded a number of exciting results. The EGRET data were analyzed using the maximum likelihood techniques to estimate the intensity, spectrum, and position of gamma-ray sources in the field of view. Our analysis revealed four sources at energies greater than 100 MeV with likelihood ratios corresponding to greater than 30 detections (Vestrand et al. 1996). One of the sources is associated with the well known gamma-ray blazar PKS 0208-512, but the other three were previously unknown. Among the new detections was PKS 2155-304 which is often considered a prototype of the x-ray selected BL Lacs. PKS 2155-304, which was also detected at hard x-ray energies by CGRO/OSSE, is one of the brightest BL Lac objects in the sky at optical through x-ray energies and has a history of rapid, strong multiwavelength variability. As such, it has been the subject of intensive, contemporaneous, multiwavelength monitoring covering radio frequencies to x-ray energies.

Vestrand, W. T.

1998-09-01

229

Highest-Energy Photons Seen by the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory.  

National Technical Information Service (NTIS)

During its nine-year lifetime, the Energetic Gamma Ray Experiment Telescope (EGBET) on the Compton Gamma Ray Observatory (CGRO) detected 1506 cosmic photons with measured energy E>10 GeV. Of this number, 187 are found within a 1 deg of sources that are...

D. J. Thompson D. L. Bertsch R. H. ONeal

2005-01-01

230

The MeV Gamma Compton Polarimeter for the SLAC FFTB Undulator Test  

Microsoft Academic Search

This note describes a Compton polarimeter for the FFTB undulator photon beam experiment at SLAC. Photons of a few MeV are scattered o polarized electrons in a thin ferromagnetic foil target. Photons are detected with a simple calorimetric detector which is mounted under a xed scattering angle behind a small collimator aperture. We have evaluated the expected performance of the

Vahagn Gharibyan; K. Peter Sch

231

New approach to low energy virtual Compton scattering and generalized polarizabilities of the nucleon  

SciTech Connect

Virtual Compton scattering off the nucleon (VCS) is studied in the regime of low energy of the outgoing real photon. This regime allows one to directly access the generalized polarizabilities of the nucleon in a VCS experiment. In the derivation of the low energy theorem for VCS that exists in the literature, the low energy limit taken for virtual initial photons does not match on that for real photons, when one approaches the initial photon's mass shell. While this problem has for a long time been attributed to the nonanalyticity of the Compton amplitude with respect to the photon virtuality, I demonstrate that it is merely due to an ill-defined low energy limit for VCS, on one hand, and to a particular way of constructing the VCS amplitude, used in the literature, on the other. I provide a uniform description of low energy Compton scattering with real and virtual photons by defining a Lorentz-covariant operator sub-basis for Compton scattering in that regime, which has six independent structures. Correspondingly, six new generalized polarizabilities are introduced in the Breit frame. These polarizabilities are defined as continuous functions of the photon virtuality and at the real photon point match onto the nucleon polarizabilities known from real Compton scattering.

Gorchtein, M. [Indiana University, Bloomington, Indiana 47408 (United States)

2010-01-15

232

Image Artifacts Resulting from Gamma-Ray Tracking Algorithms Used with Compton Imagers  

SciTech Connect

For Compton imaging it is necessary to determine the sequence of gamma-ray interactions in a single detector or array of detectors. This can be done by time-of-flight measurements if the interactions are sufficiently far apart. However, in small detectors the time between interactions can be too small to measure, and other means of gamma-ray sequencing must be used. In this work, several popular sequencing algorithms are reviewed for sequences with two observed events and three or more observed events in the detector. These algorithms can result in poor imaging resolution and introduce artifacts in the backprojection images. The effects of gamma-ray tracking algorithms on Compton imaging are explored in the context of the 4? Compton imager built by the University of Michigan.

Seifert, Carolyn E.; He, Zhong

2005-10-01

233

A regularized deconvolution-fitting method for Compton-scatter correction in SPECT  

Microsoft Academic Search

A method is presented for estimating the Compton-scatter component within the photopeak for local energy spectra measured by an Anger camera in SPECT. Assuming that the measured energy spectrum is the source scatter energy distribution convolved with a known camera energy-resolution function plus an unscattered spectral component, a least-square inverse operation is performed to recover the source scatter distribution. Since

Xiaohan Wang; Kenneth F. Koral

1992-01-01

234

Improvement of the modulation factor for a Compton scattering type polarimeter using subdivided scintillators  

Microsoft Academic Search

We are developing a Compton scattering type polarimeter, using plastic scintillators as scatterers and NaI(Tl) scintillators as detectors of scattered X rays. To improve the modulation factor keeping the good detection efficiency, we investigated the effect of subdivided plastic and NaI(Tl) scintillators for the modulation factor and the detection efficiency with basic tests and computer simulations. By measuring both x

S. Gunji; E. Kudo; H. Sakurai

1997-01-01

235

A new telescope for wide-band gamma-ray astronomy: The Silicon Compton Recoil Telescope (SCRT)  

Microsoft Academic Search

A new prototype gamma-ray telescope is described which is sensitive from 0.3 to 30 MeV as a Compton telescope and to 100 MeV as a pair detector. The Silicon Compton Recoil Telescope (SCRT) uses multilayers of silicon strip detectors as a Compton gamma-ray converter. Recoil electrons are tracked with the silicon strip detectors, and their energy losses and directions are

O. Tuemay Tuemer; Farid Ait-Ouamer; Scott C. Blair; Gary L. Case; Brendan P. O'Neill; Terrence J. O'Neill; R. Stephen White; Allen D. Zych

1994-01-01

236

Erratum: Low-energy K-shell Compton scattering [Phys. Rev. A 82, 023404 (2010)  

SciTech Connect

The first sentence of the Abstract should be as follows: We calculate the photon energy distribution and the total cross section for the Compton scattering on the K electrons for the case when the photon wavelength is much larger than the size of the K shell. The first sentence of the Summary should be as follows: We calculated the energy distributions and the total cross section for the Compton scattering on the K-shell electrons in the low-energy region, determined by Eq. (2), i.e., for the case when the wavelength of the photons is much larger than the size of the K shell.

Drukarev, E. G.; Mikhailov, A. I.; Mikhailov, I. A.

2011-02-15

237

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

238

Low-level gamma spectrometry using beta coincidence and Compton suppression.  

PubMed

A low-level gamma-ray spectrometry system was developed using a Ge(Li) detector with 6% relative efficiency coupled to a 2pi beta plastic detector for coincidence selection and a massive NaI(Tl) detector for Compton suppression. The integral background count rate for (50-1500)keV was 0.5 s(-1)kg(-1) (Ge), using only beta coincidences. With Compton suppression, a value of 0.25 s(-1)kg(-1) (Ge) was obtained. Spectra with and without Compton suppression were studied for 60Co, 137Cs and 152Eu point sources. Considerations are made concerning the Compton suppression advantages in different situations. PMID:15177343

Grigorescu, E L; De Felice, P; Razdolescu, Anamaria-Cristina; Luca, A

239

Extraction of the Compton form factor H from deeply virtual Compton scattering measurements at Jefferson Lab  

SciTech Connect

In the framework of generalized parton distributions, we study the helicity-dependent and independent cross sections measured in Hall A and the beam spin asymmetries measured in Hall B at Jefferson Laboratory. We perform a global fit of these data and fits on each kinematic bin. We extract the real and imaginary parts of the Compton form factor H under the main hypothesis of dominance of the generalized parton distribution H and twist 2 accuracy. We discuss our results and compare to previous extractions as well as to the VGG model. We pay extra attention to the estimation of errors on the extraction of H.

Moutarde, H. [CEA, Centre de Saclay, IRFU/Service de Physique Nucleaire, F-91191 Gif-sur-Yvette (France)

2009-05-01

240

Effects in K X-ray fluorescence spectra due to Compton scattering in the target  

NASA Astrophysics Data System (ADS)

In a previous study of our group, it has been shown that broad continua adjacent to the full-energy peaks (the “shoulders”) in the spectra of 59.537 keV ?-rays emitted from a standard Am241 calibration source are due to Compton scattering of ?-rays in the source plate (mass of only 0.59 g). An extension of that work is presented with the aim to show that the analogous shoulder spectra also appear in the K X-ray fluorescence spectra, and are due to the Compton scattering of fluorescence radiation in the target. The experimental set-up was carefully designed with the aim to strongly reduce single and double scattering of Am241 radiation from all surrounding materials except from the targets. An Am241 annular source was used to excite the fluorescence radiation. Measurements have been made with a target of parafine loaded with Ce2O3 and, for comparison, with a pure parafine target. To show that Compton scattering is the main cause of the observed shoulder spectra, the measurements were made for three orientations of the targets with respect to the detector-to-target centre-line. The observed changes in the measured spectra clearly show that the shoulders are mainly due to Compton scattering in the targets. Calculations of the shoulder spectra show a good agreement to the measured spectra.

Uroi?, M.; Majer, M.; Paši?, S.; Bokuli?, T.; Vukovi?, B.; Ilakovac, K.

2006-11-01

241

Use of low-energy gamma ray scattering and X-ray fluorescence in quantitative analysis  

Microsoft Academic Search

The limits of employing Rayleigh (R) and Compton (C) scattering of low energy gamma radiation for quantitative analysis are discussed. It is shown in which approximation the value of the R\\/C ratio can be considered to be a linear function of the weight fraction for binary alloys. Experimental evidence for an anomalous dispersion effect in the Rayleigh cross sections is

Carlo Bui; Mario Milazzo; Massimo Monichino

1987-01-01

242

Gamma-spectrometry with Compton suppressed detectors arrays  

Microsoft Academic Search

Recent results of experiments performed with two different Compton-suppressed detectors arrays in Daresbury and Berkeley (\\/sup 163,164\\/Yb and ¹⁵⁴Er, respectively), are presented together with a brief description of the national French array presently under construction in Strasbourg. 25 refs., 15 figs.

C. Schueck; F. Hannachi; R. Chapman; J. C. Lisle; J. N. Mo; E. Paul; D. J. G. Love; P. J. Nolan; A. H. Nelson; P. M. Walker

1985-01-01

243

Gamma-spectrometry with Compton suppressed detectors arrays  

SciTech Connect

Recent results of experiments performed with two different Compton-suppressed detectors arrays in Daresbury and Berkeley (/sup 163,164/Yb and /sup 154/Er, respectively), are presented together with a brief description of the national French array presently under construction in Strasbourg. 25 refs., 15 figs.

Schueck, C.; Hannachi, F.; Chapman, R.; Lisle, J.C.; Mo, J.N.; Paul, E.; Love, D.J.G.; Nolan, P.J.; Nelson, A.H.; Walker, P.M.

1985-01-01

244

A compton scattering spectrometer for determining X-ray photon energy spectra  

NASA Astrophysics Data System (ADS)

The importance of knowing energy spectra of the primary photons from clinical X-ray tubes under working conditions increases with the use of more sophisticated diagnostic technologies. At the high fluence rates of primary photons from diagnostic X-ray tubes it is nessesary to strongly reduce the number of photons to the detector per unit time in order to avoid pulse pileup. The compton scattering method is very suitable for this reduction. This method, applied in the diagnostic energy range by Yaffe et al. [1] is further developed in this work. The electrons moving in the target cause an energy broadening (Compton broadening) of the scattered photons. This broadening smears out the characteristic peaks of the anode material and results in a decreased energy resolution. Comparison of the spectrum obtained with the Compton spectrometer, and unfolded with our reconstruction, to the spectrum measured directly in the primary beam shows a very good agreement, although relatively simple reconstruction algorithms are used.

Matscheko, Georg; Ribberfors, Roland

1987-03-01

245

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

246

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

Microsoft Academic Search

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

Giorgio Matt; Marco Feroci; Massimo Rapisarda; Enrico Costa

1996-01-01

247

A Monte Carlo correction for the effect of Compton scattering in 3-D PET brain imaging  

Microsoft Academic Search

A Monte Carlo simulation has been developed to simulate and correct for the effect of Compton scatter in 3-D acquired PET brain scans. The method utilizes the 3-D reconstructed image volume as the source intensity distribution for a photon-tracking Monte Carlo simulation. It is assumed that the number of events in each pixel of the image represents the isotope concentration

C. S. Levin; M. Dahlbom; E. J. Hoffman

1995-01-01

248

A Real-Time Circular-Polarization Monitor For Magnetic Compton-Scattering Beamline  

SciTech Connect

A transmission-type circular polarimeter has been developed for the magnetic Compton-scattering experiment. With this device, it is possible to non-destructively monitor the approximate value of the degree of circular polarization of incident x rays during an experiment at intervals of, e.g., a few minutes.

Kawata, H.; Adachi, H.; Matsumoto, I. [Institute of Materials Structure Science, KEK, Tsukuba 305-0801 (Japan)

2004-05-12

249

X-ray Fluorescence (XRF) Assay Using Laser Compton Scattered (LCS) X-rays  

Microsoft Academic Search

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)

Syed F. Naeem; Khalid Chouffani; Douglas P. Wells

2009-01-01

250

Compton scattering from a pion: off-shell effects and the equivalence theorem.  

National Technical Information Service (NTIS)

We consider Compton scattering from a pion in the framework of chiral perturbation theory ((sub X)PT). We investigate off-shell effects in the s- and u-channel pole diagrams.For that purpose we perform a field transformation which,in comparison with the s...

S. Scherer R. W. Fearing

1994-01-01

251

Generation of Femtosecond X-Rays by 90 degrees Compton Scattering  

SciTech Connect

We propose Compton scattering of a short pulse visible laser beam by a low energy (but relativistic) electron beam at a right angle for generation of femtosecond x-rays. Simple analysis to determine the qualitative and quantitative characteristics of the x-ray pulse is presented.

Kim, K.-J.; Chattopadhyay, S.; Shank, C.V.

1992-12-01

252

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

Microsoft Academic Search

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

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

2010-01-01

253

Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering  

SciTech Connect

We present the first measurements of {rvec e}p {yields} ep{gamma} cross section in the deep virtual Compton scattering (DVCS) regime and the valence quark region (x{sub Bj} = 0.36). From JLab E00-110, we extract the imaginary part of the Bethe-Heitler (BH)--DVCS interference terms, to order twist-3 for Q{sup 2} = 1.5, 1.9, and 2.3 GeV{sup 2}, and the real part of the BH-DVCS interference terms at Q{sup 2}2 = 2.3 GeV{sup 2}. We present the first model-independent measurement of linear combinations of generalized parton distributions (GPDs) and GPD integrals up to twist-3 approximation. The validity of this approximation is strongly supported by the absence of Q{sup 2}-variation of the extracted terms--thereby constraining the size of higher twist contributions to our observables.

Carlos Munoz Camacho; Alexandre Camsonne; Malek Mazouz; Catherine Ferdi; Gagik Gavalian; Elena Kuchina; Moscov Amaryan; Konrad Aniol; Matthieu Beaumel; Hachemi Benaoum; Pierre Bertin; Michel Brossard; Jian-Ping Chen; Eugene Chudakov; Brandon Craver; Francesco Cusanno; Kees de Jager; Alexandre Deur; Robert Feuerbach; Jean Fieschi; Salvatore Frullani; Michel Garcon; Franco Garibaldi; Olivier Gayou; Ronald Gilman; Javier Gomez; Paul Gueye; Pierre Guichon; Benoit Guillon; Jens-ole Hansen; David Hayes; Douglas Higinbotham; Timothy Holmstrom; Charles Hyde-Wright; Hassan Ibrahim; Ryuichi Igarashi; Xiaodong Jiang; Hyon-Suk Jo; Lisa Kaufman; Aidan Kelleher; Ameya Kolarkar; Gerfried Kumbartzki; Geraud Laveissiere; John LeRose; Richard Lindgren; Nilanga Liyanage; Hai-jiang Lu; Demetrius Margaziotis; Zein-Eddine Meziani; Kathy McCormick; Robert Michaels; Bernard Michel; Bryan Moffit; Peter Monaghan; Sirish Nanda; Vladimir Nelyubin; Milan Potokar; Yi Qiang; Ronald Ransome; Jean-Sebastien Real; Bodo Reitz; Yves Roblin; Julie Roche; Franck Sabatie; Arunava Saha; Simon Sirca; Karl Slifer; Patricia Solvignon; Ramesh Subedi; Vincent Sulkosky; Paul Ulmer; Eric Voutier; Kebin Wang; Lawrence Weinstein; Bogdan Wojtsekhowski; Xiaochao Zheng; Lingyan Zhu

2006-07-27

254

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

255

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

256

Scaling laws in high-energy inverse compton scattering. II. Effect of bulk motions  

SciTech Connect

We study the inverse Compton scattering of the CMB photons off high-energy nonthermal electrons. We extend the formalism obtained by the previous paper to the case where the electrons have nonzero bulk motions with respect to the CMB frame. Assuming the power-law electron distribution, we find the same scaling law for the probability distribution function P{sub 1,K}(s) as P{sub 1}(s) which corresponds to the zero bulk motions, where the peak height and peak position depend only on the power-index parameter. We solved the rate equation analytically. It is found that the spectral intensity function also has the same scaling law. The effect of the bulk motions to the spectral intensity function is found to be small. The present study will be applicable to the analysis of the x-ray and gamma-ray emission models from various astrophysical objects with nonzero bulk motions such as radio galaxies and astrophysical jets.

Nozawa, Satoshi; Kohyama, Yasuharu; Itoh, Naoki [Josai Junior College, 1-1 Keyakidai, Sakado-shi, Saitama, 350-0295 (Japan); Department of Physics, Sophia University, 7-1 Kioi-cho, Chiyoda-ku, Tokyo, 102-8554 (Japan)

2010-04-15

257

Study on prompt gamma-ray spectrometer using Compton suppression system  

Microsoft Academic Search

The performance of the prompt gamma-ray activation analysis (PGAA) facility was improved by a series of modifications to the making composition of a Compton suppression system at HANARO, the 24MW research reactor in the Korea Atomic Energy Research Institute. An adjustment of the crystal was made by various efforts to obtain most suitable condition for the diffracted beam, the neutron

Hyun-Je Cho; Yong-Sam Chung; Young-Jin Kim

2005-01-01

258

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

259

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

NASA Astrophysics Data System (ADS)

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.; Nadolinsky, A. M.; Ikoeva, K. Kh.; Khoroshavina, O. A.

2011-11-01

260

Hadron annihilation into two photons and backward virtual Compton scattering in the scaling regime of QCD  

NASA Astrophysics Data System (ADS)

We study the scaling regime of hadron-(anti)hadron annihilation into a deeply virtual photon and a real photon, HH¯??*?, and backward virtual Compton scattering, ?*H?H?. We advocate that there is a kinematical region where the scattering amplitude factorizes into a short-distance matrix element and a long-distance dominated object: a transition distribution amplitude which describes the hadron to photon transition.

Pire, B.; Szymanowski, L.

2005-06-01

261

Study on prompt gamma-ray spectrometer using Compton suppression system  

NASA Astrophysics Data System (ADS)

The performance of the prompt gamma-ray activation analysis (PGAA) facility was improved by a series of modifications to the making composition of a Compton suppression system at HANARO, the 24 MW research reactor in the Korea Atomic Energy Research Institute. An adjustment of the crystal was made by various efforts to obtain most suitable condition for the diffracted beam, the neutron flux was increased by 20% at the sample position to 8.4 × 107 n cm-2 s-1, and the Compton suppression ratio was 4.3 5 times below the Compton continuum region that appeared near the sample of interest such as boron. The PGAA facility at the HANARO research reactor serves as a major analytical tool for quantifying light elements in biological, geological and food samples. The sensitivity of boron is 1468 cps/mg which is obtained from the slope of the boron peak count rate versus the boron mass. For the low background conditions, a supplement to the shielding materials on the detection assembly was made and the path of the beam line reduced the background count rate, which was evaluated from the boron data using the Compton- and single-mode. From this Compton suppressed gamma-ray spectrometer, we obtained high quality spectroscopic data from thermal neutron capture.

Cho, Hyun-Je; Chung, Yong-Sam; Kim, Young-Jin

2005-04-01

262

The Compton Gamma Ray Observatory: highlights from the first three years of the mission.  

NASA Astrophysics Data System (ADS)

The Arthur Holly Compton Gamma Ray observatory is the second in NASA's series of Great Observatories. It has been in operation for over three years, and has given a dramatic increase in capability over previous gamma-ray missions. The spacecraft and scientific instruments continue to function nearly flawlessly, and many significant discoveries have been made. The authors describe the capabilities of the four scientific instruments, and highlight some of the results from the first three years of the mission.

Gehrels, N.; Shrader, C.; Kniffen, D. A.

263

Calibration and performance of the UCR double Compton gamma ray telescope  

Microsoft Academic Search

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 Feb. 14, 1988

F. Ait-Ouamer; A. D. Kerrick; A. Sarmouk; T. J. O'Neill; W. E. Sweeney; O. T. Tumer; A. D. Zych; R. S. White

1990-01-01

264

Calibration and performance of the UCR double Compton gamma ray telescope  

Microsoft Academic Search

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

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

1990-01-01

265

Simulated Performance of the Nuclear Compton Telescope as a Gamma-Ray Polarimeter  

Microsoft Academic Search

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. NCT is sensitive to polarization in the range 0.2-1 MeV. NCT consists of 3D position-sensitive germanium strip detectors. The ultra-compact design and new technologies allow NCT to achieve high efficiencies with excellent spectral resolution and

Jau-Shian Liang; E. C. Bellm; S. E. Boggs

2008-01-01

266

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

267

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

Microsoft Academic Search

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

Tinsley

1990-01-01

268

Development of a High-Average-Power Compton Gamma Source for Lepton Colliders  

SciTech Connect

Gamma-({gamma}{sup -}) ray beams of high average power and peak brightness are of demand for a number of applications in high-energy physics, material processing, medicine, etc. One of such examples is gamma conversion into polarized positrons and muons that is under consideration for projected lepton colliders. A {gamma}-source based on the Compton backscattering from the relativistic electron beam is a promising candidate for this application. Our approach to the high-repetition {gamma}-source assumes placing the Compton interaction point inside a CO{sub 2} laser cavity. A laser pulse interacts with periodical electron bunches on each round-trip inside the laser cavity producing the corresponding train of {gamma}-pulses. The round-trip optical losses can be compensated by amplification in the active laser medium. The major challenge for this approach is in maintaining stable amplification rate for a picosecond CO{sub 2}-laser pulse during multiple resonator round-trips without significant deterioration of its temporal and transverse profiles. Addressing this task, we elaborated on a computer code that allows identifying the directions and priorities in the development of such a multi-pass picosecond CO{sub 2} laser. Proof-of-principle experiments help to verify the model and show the viability of the concept. In these tests we demonstrated extended trains of picosecond CO{sub 2} laser pulses circulating inside the cavity that incorporates the Compton interaction point.

Pogorelsky, Igor; Polyanskiy, Mikhail N.; Yakimenko, Vitaliy [Brookhaven National Laboratory, bldg. 820M, Upton, NY 11973 (United States); Platonenko, Viktor T. [Lomonosov Moscow State University, Physics Department, Vorob'evy Gory 119992 (Russian Federation)

2009-01-22

269

Low-level gamma spectrometry using beta coincidence and Compton suppression  

Microsoft Academic Search

A low-level gamma-ray spectrometry system was developed using a Ge(Li) detector with 6% relative efficiency coupled to a 2? beta plastic detector for coincidence selection and a massive NaI(Tl) detector for Compton suppression.The integral background count rate for (50–1500)keV was 0.5s?1kg?1 (Ge), using only beta coincidences. With Compton suppression, a value of 0.25s?1kg?1 (Ge) was obtained. Spectra with and without

E. L Grigorescu; P. De Felice; Anamaria-Cristina Razdolescu; A Luca

2004-01-01

270

A Compton suppression gamma-ray spectrometer for low level counting  

Microsoft Academic Search

A Compton suppression gamma-ray spectrometry system has been evaluated for its use as a low level radioactivity counting facility.\\u000a The system consists of a premium quality Ge(Li) detector surrounded by a shield of NaI(T1) detector material. Compton suppression\\u000a is obtained by operating the two detector systems in anti-coincidence. Spectrum collection hardware consists of a NP11-A (DEC)\\u000a interface for two ADC's

J. Op De Beeck; A. Isebaert; J. Hoste

1983-01-01

271

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

272

A spectrometer for Compton scattering studies of heavy elements and the problem of bremsstrahlung background  

NASA Astrophysics Data System (ADS)

A high energy Compton spectrometer which operates at either 662 keV or 412 keV with the ?-ray sources 198Au and 137Cs, respectively, has been designed and built. Measurements conducted on Al, Cu and Ag samples indicate the usefulness of this spectrometer for studies of electron momentum distributions. Systematic discrepancies observed between the experimental and theoretical Compton profiles of silver are thought to originate from a background of bremsstrahlung radiation, associated with the Compton recoil electrons and photoelectrons, which is not significant in studies of lighter elements or with lower energy sources. The problem caused by the presence of the additional background in the scattering of high energy radiation from heavy elements is discussed.

Andrejczuk, A.; ?ukowski, E.; Dobrzy?ski, L.; Cooper, M. J.

1993-12-01

273

Compton-suppression gamma counting in the neutron activation analysis measurement of noble metals  

SciTech Connect

Recent interest in studying elemental abundance anomalies associated with the Cretaceous and Tertiary (K-T) boundary in geologic strata has increased the importance of analytical methods for the determination of low levels of iridium and other noble metals. The determination of iridium anomalies that are in the range from 1 to 100 {mu}g/kg (ppb) requires radiochemical separation procedures following neutron activation. Faster and less laborious instrumental neutron activation analysis (NAA) techniques using elaborate Compton-suppression gamma counters are under development. Compton-suppression gamma counting (CSGC) uses anticoincidence shielded Ge(Li) detectors that enhance the signal-to-background ratios for gamma photopeaks situated on high Compton backgrounds. In this method, an anti- or noncoincidence spectrum and a coincidence spectrum are collected simultaneously. Most Compton-suppression counting has been done at low count rates, but neutron-activated samples ordinarily produce much higher count rates. In the work reported in this paper, K-T boundary and adjacent samples were neutron irradiated, the noble metals separated as a group, and the noble metal group separately counted using CSGC. Iridium, gold, platinum, and silver were determined. The counting data from these analyses were available for a thorough evaluation of the value of CSGC to the determination of this particular suite of noble metals in geologic samples.

Millard, H.T. Jr.

1988-01-01

274

Experimental observation of energy dependence of saturation thickness of multiply scattered gamma photons  

NASA Astrophysics Data System (ADS)

The gamma photons continue to soften in energy as the number of scatterings increases in the target having finite dimensions both in depth and lateral dimensions. The number of multiply scattered photons increases with an increase in target thickness, and saturates at a particular value of the target thickness known as saturation thickness (depth). The present measurements are carried out to study the energy dependence of saturation thickness of multiply scattered gamma photons from targets of various thicknesses. The scattered photons are detected by a properly shielded NaI(Tl) gamma ray detector placed at 90° to the incident beam. We observe that the saturation thickness increases with increasing incident gamma photon energy. Monte Carlo calculations based upon the package developed by Bauer and Pattison [Compton 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.

2008-09-01

275

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

276

The integration of improved Monte Carlo compton scattering algorithms into the Integrated TIGER Series.  

SciTech Connect

The Integrated TIGER Series (ITS) is a software package that solves coupled electron-photon transport problems. ITS performs analog photon tracking for energies between 1 keV and 1 GeV. Unlike its deterministic counterpart, the Monte Carlo calculations of ITS do not require a memory-intensive meshing of phase space; however, its solutions carry statistical variations. Reducing these variations is heavily dependent on runtime. Monte Carlo simulations must therefore be both physically accurate and computationally efficient. Compton scattering is the dominant photon interaction above 100 keV and below 5-10 MeV, with higher cutoffs occurring in lighter atoms. In its current model of Compton scattering, ITS corrects the differential Klein-Nishina cross sections (which assumes a stationary, free electron) with the incoherent scattering function, a function dependent on both the momentum transfer and the atomic number of the scattering medium. While this technique accounts for binding effects on the scattering angle, it excludes the Doppler broadening the Compton line undergoes because of the momentum distribution in each bound state. To correct for these effects, Ribbefor's relativistic impulse approximation (IA) will be employed to create scattering cross section differential in both energy and angle for each element. Using the parameterizations suggested by Brusa et al., scattered photon energies and angle can be accurately sampled at a high efficiency with minimal physical data. Two-body kinematics then dictates the electron's scattered direction and energy. Finally, the atomic ionization is relaxed via Auger emission or fluorescence. Future work will extend these improvements in incoherent scattering to compounds and to adjoint calculations.

Quirk, Thomas, J., IV (University of New Mexico)

2004-08-01

277

A K edge filter technique for optimization of the coherent-to-Compton scatter ratio method.  

PubMed

The ratio method involves forming the ratio of the elastic to inelastic x-ray scatter signals from a localized region of a scattering medium to determine its mean atomic number. An analysis is presented of two major error sources influencing the ratio method: firstly statistical (photon) noise and secondly multiple scattering and self-attenuation of the primary and scatter radiations in the medium. It is shown that a forward scattering geometry minimizes errors of both types for substances composed of elements with low and medium atomic number. However, owing to the small energy separation (approximately 100 eV) of coherent and Compton scatter for this geometry, they cannot be distinguished directly with semiconductor (e.g., Ge) detectors. A novel K edge filter technique is described which permits separation of the elastic and Compton signals in the forward-scatter geometry. The feasibility of this method is demonstrated by experimental results obtained with Ta fluorescence radiation provided by a fluorescent x-ray source filtered with an Er foil. The extension of this technique to the "in vivo" measurement of low momentum transfer inelastic scattering from biological tissues, possibly providing useful diagnostic information, is briefly discussed. PMID:8746705

Harding, G; Armstrong, R; McDaid, S; Cooper, M J

1995-12-01

278

A Set of Monte Carlo Subroutines for Treating the Physics of Compton Scattering  

SciTech Connect

A set of portable Monte Carlo subroutines is presented to treat the physics of Compton scattering. Electron binding energies are included by the modification of the Klein-Nishina probability distribution by the incoherent scattering function. In addition the scattered photon's energy is calculated by taking into account the momentum distribution of the electron. These subroutines have been verified and validated by calculating the total cross section over incident photon energies of 10 keV to 100 MeV for elements of Z=l to Z=l 00 and are within 1.08% of published values.

John Lestone; Jonathan Earnhart; Thomas Prettyman

1998-12-01

279

Comment on 'Anomalous neutron Compton scattering from molecular hydrogen'  

SciTech Connect

Claims in the paper by Chatizidimitiou-Dreismann et al. [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 {approx}21% in the scattering intensity ratio of H{sub 2}O relative to that of D{sub 2}O.

Moreh, R. [Physics Department, Ben-Gurion University of the Negev, Beer-Sheva (Israel); Gaerttner LINAC Laboratory, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Block, R. C.; Danon, Y. [Gaerttner LINAC Laboratory, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2007-02-01

280

Compton scattering from a pion: Off-shell effects and the equivalence theorem  

SciTech Connect

We consider Compton scattering from a pion in the framework of chiral perturbation theory ({chi}{ital PT}). We investigate off-shell effects in the s- and u-channel pole diagrams. For that purpose we perform a field transformation which, in comparison with the standard Gasser and Leutwyler lagrangian, generates additional terms at order {ital p}{sup 4} proportional to the lowest-order equation of motion. We demonstrate that the two lagrangians which generate different off-shell form factors predict the same Compton scattering S-matrix. This result is interpreted as an application of a generalized equivalence theorem. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Scherer, S.; Fearing, H.W. [TRIUMF, 4004 Wesbrook Mall, Vancouver, B.C., V6T 2A3 (Canada)

1995-05-10

281

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

282

Deeply virtual Compton scattering on the neutron at JLab Hall A  

SciTech Connect

Deeply virtual Compton scattering (DVCS) is the simplest hard exclusive process to access generalized parton distributions (GPDs). In the case of a neutron this process is mostly sensitive to E, the least constrained GPD, which enters Ji's sum rule linking GPDs to the total quark angular momentum. We present the first dedicated DVCS experiment on the neutron which took place in the Hall A of Jefferson Lab in fall 2004. Experimental setup and preliminary results are discussed.

M. Mazouz

2007-02-01

283

Performance of Prototype Hard X-ray Polarimeter Utilizing Compton Scattering  

Microsoft Academic Search

In X-ray astronomy, various kinds of information on stellar objects have been obtained from energy spectrum, time variabilities, and images. Although the observation of polarization is also important, it has not been carried out for 25 years, because of the difficulty of developing a polarimeter with a high sensitivity. Thus, we have been developing a Compton-scattering-type hard X-ray polarimeter sensitive

Toshiji Suzuki; Shuichi Gunji; Ryo Nakajima; Yuichiro Yamashita; Kazufumi Suzuki; Hirohisa Sakurai; Fuyuki Tokanai; Ken Takashima; Yoshihito Kobayashi; Kenichi Tamura; Shunji Kishimoto

2006-01-01

284

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

Microsoft Academic Search

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

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

2007-01-01

285

Effects in K X-ray fluorescence spectra due to Compton scattering in the target  

Microsoft Academic Search

In a previous study of our group, it has been shown that broad continua adjacent to the full-energy peaks (the “shoulders”) in the spectra of 59.537keV ?-rays emitted from a standard Am241 calibration source are due to Compton scattering of ?-rays in the source plate (mass of only 0.59g). An extension of that work is presented with the aim to

M. Uroic; M. Majer; S. Pasic; T. Bokulic; B. Vukovic; K. Ilakovac

2006-01-01

286

X-ray Fluorescence (XRF) Assay Using Laser Compton Scattered (LCS) X-rays  

Microsoft Academic Search

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)

Syed F. Naeem; Khalid Chouffani; Douglas P. Wells

2009-01-01

287

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

288

ON THE SPECTRAL SHAPE OF RADIATION DUE TO INVERSE COMPTON SCATTERING CLOSE TO THE MAXIMUM CUTOFF  

SciTech Connect

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., E-mail: eva.lefa@mpi-hd.mpg.de [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, 69029 Heidelberg (Germany)

2012-07-10

289

Status of the Polarized Nonlinear Inverse Compton Scattering Experiment at UCLA  

SciTech Connect

An Inverse Compton Scattering (ICS) experiment investigating the polarized harmonic production in the nonlinear regime has begun which will utilize the existing terawatt CO2 laser system and 15 MeV photoinjector in the Neptune Laboratory at UCLA. A major motivation for a source of high brightness polarized x-rays is the production of polarized positrons for use in future linear collider experiments. We report on the experimental set-up and status.

Williams, O.; Doyuran, A.; England, R. J.; Rosenzweig, J. B.; Travish, G. [Department of Physics and Astronomy, University of California, Los Angeles (United States); Joshi, C.; Tochitsky, S. [Department of Electrical Engineering, University of California, Los Angeles, Los Angeles, CA 90095 (United States)

2006-11-27

290

Generalized parton distributions in the valence region from deeply virtual compton scattering  

NASA Astrophysics Data System (ADS)

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.

Guidal, Michel; Moutarde, Hervé; Vanderhaeghen, Marc

2013-06-01

291

Measurement of Deeply Virtual Compton Scattering with a Polarized-Proton Target  

Microsoft Academic Search

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

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

2006-01-01

292

Observation of Exclusive Deeply Virtual Compton Scattering in Polarized Electron Beam Asymmetry Measurements  

Microsoft Academic Search

We report the first results of the beam-spin asymmetry measured in the reaction e-->p-->epgamma at a beam energy of 4.25 GeV. A large asymmetry with a sinphi modulation is observed, as predicted for the interference term of deeply virtual compton scattering (DVCS) and the Bethe-Heitler process. The amplitude of this modulation is alpha = 0.202+\\/-0.028. In leading-order and leading-twist perturbative

S. Stepanyan; V. D. Burkert; L. Elouadrhiri; G. S. Adams; E. Anciant; M. Anghinolfi; B. Asavapibhop; G. Audit; T. Auger; H. Avakian; J. Ball; S. Barrow; M. Battaglieri; K. Beard; M. Bektasoglu; P. Bertin; N. Bianchi; A. Biselli; S. Boiarinov; B. E. Bonner; S. Bouchigny; D. Branford; W. K. Brooks; J. R. Calarco; D. S. Carman; B. Carnahan; L. Ciciani; P. L. Cole; A. Coleman; D. Cords; P. Corvisiero; D. Crabb; H. Crannell; J. Cummings; P. V. Degtiarenko; H. Denizli; L. C. Dennis; E. de Sanctis; R. Devita; K. V. Dharmawardane; C. Djalali; G. E. Dodge; D. Doré; D. Doughty; P. Dragovitsch; S. Dytman; M. Eckhause; H. Egiyan; K. S. Egiyan; A. Empl; R. Fatemi; R. J. Feuerbach; J. Ficenec; K. Fissum; T. A. Forest; A. P. Freyberger; H. Funsten; S. Gaff; M. Gai; M. Garçon; G. Gavalian; S. Gilad; G. P. Gilfoyle; K. Giovanetti; P. Girard; K. A. Griffioen; M. Guidal; M. Guillo; V. Gyurjyan; C. Hadjidakis; J. Hardie; D. Heddle; F. W. Hersman; K. Hicks; R. S. Hicks; M. Holtrop; J. Hu; C. E. Hyde-Wright; M. M. Ito; D. Jenkins; K. Joo; J. Kelley; M. Khandaker; D. H. Kim; K. Kim; W. Kim; A. Klein; F. J. Klein; M. Klusman; M. Kossov; L. H. Kramer; S. E. Kuhn; J. M. Laget; D. Lawrence; A. Longhi; K. Lukashin; J. J. Manak; C. Marchand; S. McAleer; J. McCarthy; J. W. McNabb; B. A. Mecking; M. D. Mestayer; C. A. Meyer; K. Mikhailov; R. Minehart; M. Mirazita; R. Miskimen; L. Morand; V. Muccifora; J. Mueller; G. S. Mutchler; J. Napolitano; S. Nelson; S. Niccolai; G. Niculescu; I. Niculescu; R. A. Niyazov; A. Opper; G. O'Rielly; J. T. O'Brien; E. Pasyuk; G. A. Peterson; S. Philips; N. Pivnyuk; D. Pocanic; O. Pogorelko; E. Polli; I. Popa; S. Pozdniakov; B. M. Preedom; J. W. Price; D. Protopopescu; L. M. Qin; B. A. Raue; A. R. Reolon; G. Riccardi; G. Ricco; M. Ripani; B. G. Ritchie; F. Ronchetti; P. Rossi; D. Rowntree; P. D. Rubin; F. Sabatié; K. Sabourov; C. W. Salgado; V. Sapunenko; R. A. Schumacher; V. Serov; Y. G. Sharabian; J. Shaw; S. Simionatto; A. Skabelin; E. S. Smith; L. C. Smith; D. I. Sober; A. Stavinsky; P. Stoler; I. I. Strakovsky; R. Suleiman; M. Taiuti; S. Taylor; D. Tedeschi; R. Thompson; L. Todor; M. F. Vineyard; A. Vlassov; K. Wang; H. Weller; L. B. Weinstein; R. Welsh; D. P. Weygand; S. Whisnant; E. Wolin; A. Yegneswaran; J. Yun; J. Zhao; B. Zhang; Z. Zhou

2001-01-01

293

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

2013-05-30

294

Observations of gamma radiation between 0.4 MeV and 7 MeV at balloon altitudes using a Compton telescope  

NASA Astrophysics Data System (ADS)

Balloon-borne measurements of the atmospheric and diffuse gamma-ray flux in the energy range 0.4-7.0 MeV 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, are reported. Comparison of the diffuse cosmic gamma-ray flux to the atmospheric gamma rays indicates that 0.2-5.0 MeV is the optimum energy range for measurements made at the top of the earth's atmosphere. The measured total atmospheric gamma-ray flux between zero and 40 deg has an energy spectrum that agrees with the calculations of Ling (1975). Observations indicate that the ratio of the diffuse to atmospheric gamma ray fluxes at 3.5 g/sq cm is a maximum, about 1.0, between 0.7 and 3.0 MeV.

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

1981-09-01

295

Gamma rays from SN1987A with the UCR double-Compton telescope  

Microsoft Academic Search

Results are presented for gamma rays from SN1987A observed on a flight of the UCR double Compton telescope from Alice-Springs, Australia, 15 to 16 April 1988, some 418 days after SN1987A explosion. The calibrations before the flight gave energy resolutions of 13 pct. FWHM at 1.35 MeV and 10 pct. FWHM at 2.75 MeV and an angular resolution of 11

Farid Ait-Ouamer

1991-01-01

296

Compton suppression gamma-spectroscopy in the analysis of radium and lead isotopes in ocean sediments  

Microsoft Academic Search

Compton suppression gamma-spectroscopy provides an efficient method for measuring the concentration of226Ra,228Ra, and210Pb in ocean sediments. The background reduction realized from the suppressed mode of operation provides an “active shield”\\u000a to allow for the low-level counting required for these measurements. We have used the method to study the possible accumulation\\u000a of radium from produced waters in sediments from Gulf of

W. D. James; P. N. Boothe; B. J. Presley

1998-01-01

297

Development of a Lxe-Tpc Compton Telescope for Gamma-Ray Astronomy  

Microsoft Academic Search

A Liquid Xenon Time Projection Chamber (LXe-TPC) Compton telescope has been developed. It will be used as a balloon borne instrument to perform astronomical observations in the low and medium energy gamma-ray range between 0.3 and 30 MeV, with an angular resolution of 1-3 degrees and a field-of-view of 40o . The feasibility of large volume LXe detectors was first

Fang Xu

1998-01-01

298

Rayleigh and Compton scattering analysis for PMMA in the mammography energy range  

Microsoft Academic Search

\\u000a The method of obtaining the primary x-ray spectrum by the Compton scattering correction has been practically established for\\u000a relatively high x-ray tube voltages. However, for mammography, the tube voltages are less than 30 to 35 kV and there exists\\u000a an intense characteristic x-ray peak at 17.5 keV from the molybdenum target. The influence of Rayleigh scattering can not\\u000a be neglected

Yoshiki Yamaguchi; Souichiro Kawaguchi; Hidetaka Arimura; Junji Morishita; Masafumi Ohki; Yoshinori Uno; Tadamitsu Ideguchi; Kenji Tokumori; Yoshiharu Higashida; Fukai Toyofuku

299

Complete order-{alpha}{sup 3} calculation of the cross section for polarized Compton scattering  

SciTech Connect

The construction of a computer code to calculate the cross sections for the spin-polarized processes e{sup {minus}}{gamma}{r_arrow}e{sup {minus}}{gamma},e{sup {minus}}{gamma}{gamma},e{sup {minus}}e{sup +}e{sup {minus}} to order {alpha}{sup 3} is described. The code calculates cross sections for circularly polarized initial-state photons and arbitrarily polarized initial-state electrons. The application of the code to the SLD Compton polarimeter indicates that the order-{alpha}{sup 3} corrections produce a fractional shift in the SLC polarization scale of {minus}0.1{percent} which is too small and of the wrong sign to account for the discrepancy in the Z-pole asymmetries measured by the SLD Collaboration and the CERN LEP Collaborations. {copyright} {ital 1998} {ital The American Physical Society}

Swartz, M.L. [Stanford Linear Accelerator Center, Stanford University, Stanford, California 94309 (United States)

1998-07-01

300

Compton scattering, meson exchange, and the polarizabilities of bound nucleons  

SciTech Connect

Elastic photon scattering cross sections on {sup 16}O have been measured in the energy range 27{endash}108 MeV. These data are inconsistent with a conventional interpretation in which the electric and magnetic polarizabilities of the bound nucleon are unchanged from the free values and the meson-exchange seagull amplitude is taken in the zero-energy limit. Agreement with the data can be achieved by invoking either strongly modified polarizabilities or a substantial energy dependence to the meson-exchange seagull amplitude. It is argued that these seemingly different explanations are experimentally indistinguishable and probably physically equivalent. {copyright} {ital 1996 The American Physical Society.}

Feldman, G.; Mellendorf, K.E.; Eisenstein, R.A.; Federspiel, F.J.; Garino, G.; Igarashi, R.; Kolb, N.R.; Lucas, M.A.; MacGibbon, B.E.; Mize, W.K.; Nathan, A.M.; Pywell, R.E.; Wells, D.P. [Saskatchewan Accelerator Laboratory, University of Saskatchewan, Saskatoon, Saskatchewan, S7N 5C6 (CANADA)]|[Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)

1996-11-01

301

Bound-Compton profiles for inelastic x-ray scattering in warm, dense matter  

NASA Astrophysics Data System (ADS)

Inelastic x-ray scattering has recently been developed as a powerful diagnostic method for determining the densities and temperatures of warm dense matter. Accurate measurements require determination of the spectral bound-free Compton profile. Thus, improved models of bound-free transitions are of great interest to correctly infer the inelastic scattering component from bound and free electrons, particularly in mid-Z systems. We present inelastic scattering spectra taken from un-shocked samples of Boron at the Advanced Photon Source (APS) synchrotron and laser-driven samples at LLNL's Titan laser. These spectra are compared with profiles calculated within the impulse approximation. These measured profiles provide an important tool for analyzing scattering in warm, dense systems. Additionally, they will be used as a benchmark for an improved self-consistent-field model of bound-free transitions currently in development.

Davis, Paul; Gregori, Gianluca; Bradley, Joe; Seidler, Jerry; Neumayer, Paul; Falcone, Roger; Doeppner, Tilo; Ralph, Joe; Glenzer, Siegfried

2009-11-01

302

Neutron Compton scattering from water studied with the double-difference technique  

SciTech Connect

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). The standard analysis of NCS data has been subject to severe criticism, e.g., it was claimed that it is the way the energy resolution function is incorporated in the data reduction scheme that leads to an underestimation of the scattering intensity. Here we present NCS experimental results utilizing a technique--referred to as double difference--which significantly improves the energy resolution function. Specifically, the ratio of the scattering cross-section density of H and D in mixtures of light and heavy water are presented. The experimental data reveal that the results published earlier remain unchanged upon the significant improvement of the energy resolution function.

Abdul-Redah, T. [Physics Laboratory, The University of Kent at Canterbury, Canterbury, Kent CT2 7NR (United Kingdom); Krzystyniak, M.; Chatzidimitriou-Dreismann, C.A. [Institute of Chemistry, Stranski Laboratory, Technical University of Berlin, D-10623 Berlin (Germany)

2005-08-01

303

Anisotropic inverse Compton scattering from the circumstellar disc in PSR B1259-63  

NASA Astrophysics Data System (ADS)

The gamma-ray binary system PSR B1259-63 has been detected from radio to very high energy gamma-rays. The presence of an extended circumstellar disc around the Be optical companion suggests the possibility that the IR flux from the disc will provide additional target photons for inverse Compton gamma-ray production and could result in an increase in the gamma-ray flux, particularly at GeV energies. The extent of the IR excess is modelled by making use of a curve of growth method, which is fitted to optical and near-IR archive observations and mid-IR observations obtained with the VLT on 5 January 2011. The anisotropic inverse Compton emission is modelled around periastron by assuming a constant, adiabatically cooled electron distribution. The results show that the IR flux can increase the GeV emission by a factor > 2, with the maximum contribution occurring at periastron and not near the disc crossing epoch. A flare from PSR B1259-63 was detected with the Fermi telescope with an implied luminosity of ~ 100 per cent of the spin-down luminosity of the pulsar, approximately 30 days after the 2010 periastron. This unexpected flare cannot be explained by this model without incorporating additional effects to greatly increase the IR photon density near the disc crossing.

van Soelen, B.; Meintjes, P. J.

2012-12-01

304

The BATSE experiment on the Compton Gamma Ray Observatory: Status and some early results  

NASA Astrophysics Data System (ADS)

The Burst and Transient Source Experiment (BATSE) on the Compton Gamma Ray Observatory (GRO) is a sensitive all-sky detector system. It consists of eight uncollimated detectors at the corners of the spacecraft which have a total energy range of 15 keV to 100 MeV. The primary objective of BATSE is the detection, location, and study of gamma ray bursts and other transient sources. The instrement also has considerable capability for the study of pulsars, solar flares, and other discrete high energy sources. The experiment is now in full operation, detecting about one gamma ray burst per day. A brief description of the on-orbit performance of BATSE is presented, along with examples of early results from some of the gamma ray bursts.

Fishman, G. J.; Meegan, C. A.; Wilson, R. B.; Paciesas, W. S.; Pendleton, G. N.

1992-02-01

305

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

2011-11-09

306

X-ray standing wave induced Compton and elastic scattering from thin periodic multilayer structures  

NASA Astrophysics Data System (ADS)

We report determination of structural parameters on angstrom length scale of nanostructured periodic multilayers using x-ray standing wave (XSW) enhanced elastic and Compton scattering. We show that the elastic scattered x-ray intensities emitted from the thin periodic multilayer structures, under strong XSW condition, are largely sensitive to the structural parameters of high-z layers, whereas the Compton scattered intensities are sensitive to the parameters of low-z layers. The utility of the methodology is demonstrated by analyzing two repetitive W/B4C multilayer structures with different surface-interface properties. The results are compared with those obtained using x-ray reflectivity and conventional x-ray standing wave fluorescence techniques. It is further shown that the Bragg angle can be derived with high accuracy (˜0.002?) from the ratio of the scattering intensities, which in turn improves the accuracy of the derived multilayer periodicity. The method presents an opportunity to probe structures on angstrom length scale of any periodic multilayer structure comprising of low atomic number layers. Unlike the conventional XSW fluorescence measurements, the present method has an advantage that it permits the determination of structural parameters of both the high- and the low-z layers independently.

Tiwari, M. K.; Wang, H.; Sawhney, K. J. S.; Nayak, M.; Lodha, G. S.

2013-06-01

307

Compton telescope observations of gamma rays from SN 1987A  

Microsoft Academic Search

Results are reported of observations of a significant excess of gamma rays at energies of 1.0-2.5 MeV from the direction of SN 1987A, 418 days after detonation. Two features at 1.21 and 1.88 MeV are attributed to the 1.238 MeV and the combined 1.771, 2.015, and 2.035 MeV line emissions from the decay of Co-56 in the expanding ejecta with

Farid Ait-Ouamer; Alan D. Kerrick; Terrence J. O'Neill; O. T. Tumer; Allen D. Zych; R. S. White

1992-01-01

308

Determination of Copper by Neutron Activation Analysis in Conjunction with Compton Suppression Gamma Spectrometry  

SciTech Connect

Copper is considered to be an essential element. Its accurate determination in tissues, foods, and other biological materials is needed to study the effect of copper on human nutrition and health. Using and Advance Prediction Computer Program, it has been shown that short-lived {sup 66}Cu (half-life = 5.09 min) can be used to determine copper in biological materials by instrumental neutron activation analysis (INAA). However, it is seldom done in practice-in particular, for low copper content in high-salt biological materials-because of the Compton background interference from nuclides such as {sup 28}Al, {sup 38}Cl, and {sup 24}Na. To eliminate the Compton interference, a preconcentration NAA method has recently been developed in our laboratory using reversed-phase extraction chromatography of copper followed by short irradiation and conventional gamma-spectrometric counting of {sup 66}Cu; the detection limit is {approx}5 ppb.

W. H. Zhang; A. Chatt

2000-06-04

309

INVERSE COMPTON EMISSION FROM THE PROMPT OPTICAL EMISSION REGION IN GAMMA-RAY BURSTS  

SciTech Connect

Prompt optical emission accompanying gamma-ray emission has been detected in several gamma-ray bursts (GRBs), and its origin is still under debate. A plausible interpretation is that the prompt optical emission is generated by internal shocks but from regions different from the prompt gamma-ray one. Based on this model, we investigate in detail the inverse Compton (IC) emission including the synchrotron self-Compton (SSC) and second inverse Compton (2IC) ones from the optical emission region. We expect that this study could provide a clue to the origin of prompt optical emission. We first explore the dependence of IC Y factor on some uncertain parameters such as the magnetic field equipartition factor and the Lorentz factor of GRB ejecta. The results indicate that the 2IC emission associated with strong optical flashes (such as GRB 080319b) may be easily detected by Fermi for general parameters. If the SSC peak energy is in the range of tens-to-hundreds keV but generally much weaker than the prompt gamma-ray emission, the component may be detectable by Swift (BAT). For moderately bright optical flashes, the 2IC emission is marginally detectable while the SSC is not. For weak optical flashes, both the 2IC and SSC components are undetectable. We then carry out a numerical calculation of the expected spectrum including synchrotron, SSC, and the 2IC emission for various parameters, which verifies the analytical results. Finally, taking GRB 080319b as an example, we make a simple case study. We find that the detection of the 2IC emission optical region by Fermi is promising. The future simultaneous detection of optical and high energy (MeV-GeV) from the emissions will possibly reveal the nature of the prompt optical emission and allow us to measure the quantities presently unknown such as the bulk Lorentz factor, radiative electrons energy, and magnetic field.

Zhao, X. H.; Dai, Z. G.; Liu, T. [Department of Astronomy, Nanjing University, Nanjing 210093 (China); Bai, J. M. [National Astronomical Observatories/Yunnan Observatory, Chinese Academy of Sciences, P.O. Box 110, 650011 Kunming (China); Peng, Z. Y., E-mail: xhzhao@nju.edu.c, E-mail: pzy@ynao.ac.c [Department of Physics, Yunnan Normal University, Kunming 650092 (China)

2010-01-10

310

Direct observation of the magnetic spin component of samarium–iron-based laves compound by magnetic Compton scattering  

Microsoft Academic Search

The spin-polarized electron momentum distributions (magnetic Compton profiles: MCP's) of SmFe1.86Al0.14 along the [111] direction have been measured at 10 and 300K using the magnetic Compton scattering technique. It is found that the orbital moment dominates the magnetization in this compound. A comparison with a theoretical profile support that the shape of the experimental MCP's is reproduced by a sum

S. Mizusaki; N. Kawamura; T. Taniguchi; M. Itou; H. Samata; Y. Noro; Y. Sakurai; Y. Nagata

2007-01-01

311

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

312

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

313

Trabecular bone mineral density measurement in vivo: use of the ratio of coherent to Compton-scattered photons in the calcaneus.  

PubMed

Trabecular bone mineral density (TBMD) was measured in vivo in the calcaneus by a new method that uses the ratio of coherent to Compton-scattered photons arising from irradiation of a small volume of trabecular bone by a gamma ray source with highly collimated geometry. TBMD values for healthy men (22-77 years) were in the range of 180-357 mg/ml, and values for healthy women (18-73 years) were in the range of 160-321 mg/ml. In contrast, values in a small group of paraplegics were in the range of 90-199 mg/ml. PMID:3945741

Shukla, S S; Leichter, I; Karellas, A; Craven, J D; Greenfield, M A

1986-03-01

314

Study of Generalized Parton Distributions and Deeply Virtual Compton Scattering on the nucleon with the CLAS and CLAS12 detectors at the Jefferson Laboratory  

SciTech Connect

The exclusive leptoproduction of a real photon is considered to be the "cleanest" way to access the Generalized Parton Distribution (GPD). This process is called Deeply Virtual Compton Scattering (DVCS) lN {yields} lN{gamma} , and is sensitive to all the four GPDs. Measuring the DVCS cross section is one of the main goals of this thesis. In this thesis, we present the work performed to extract on a wide phase-space the DVCS cross-section from the JLab data at a beam energy of 6 GeV.

Baptiste Guegan

2012-11-01

315

Polarimetric Performance of the Nuclear Compton Telescope  

NASA Astrophysics Data System (ADS)

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray telescope. Its compact design uses cross-strip germanium detectors, allowing for wide-field imaging with excellent efficiency from 0.2-10 MeV. Additionally, the Compton imaging principle employed by NCT provides polarimetric sensitivity from 0.2-2 MeV. We conducted laboratory observations of a partially polarized beam produced by scattering gamma-rays off of a CsI scintillator slab. We present results of these measurements and compare them with detailed Monte Carlo simulations in order to assess NCT's capabilities as a Compton polarimeter.

Bellm, Eric C.; Boggs, S. E.; NCT Collaboration

2011-09-01

316

Nucleon Polarisabilities from Deuteron Compton Scattering, and Its Lessons for Chiral Power Counting  

NASA Astrophysics Data System (ADS)

Chiral Effective Field Theory with explicit ?(1232) degree of freedom is for photon energies up to 300 MeV the tool to accurately determine the polarisabilities of the proton and neutron from Compton scattering experiments in a model-independent and systematic way. It proves in particular indispensable to understand deuteron Compton scattering at 95 MeV as measured at SAL. Simple consistency arguments derived from nuclear phenomenology lead for the deuteron case to the correct Thomson limit, demonstrating gauge-invariance and shedding new light on Weinberg's proposed power-counting of nuclear forces. In our global analysis of all elastic proton and deuteron Compton scattering up to 150 MeV, we find for the static scalar dipole polarisabilities ?^p=(11.0±1.4stat±0.4sys)x10-4 ;fm^3, ?^p=(2.81.4stat±0.4syst)x10-4;fm^3 for the proton and ?^n=(11.6±1.5stat±0.6syst)x10-4;fm^3 ?^n=(3.61.5stat±0.6syst)x10-4;fm^3 for the neutron. Therefore, proton and neutron polarisabilities are identical within the accuracy of available data. New experiments e.g. at MAXlab (Lund) will improve the statistical error-bar. [1] R. P. Hildebrandt, H. W. Grießhammer and T. R. Hemmert, submitted to Phys. Rev. C [nucl-th/0512063]. [2] H. W. Grießhammer: Power-Counting in Chiral EFT from a Minimum of Phenomenology, in preparation.

Griesshammer, Harald W.

2006-10-01

317

Nucleon Polarisabilities from Deuteron Compton Scattering, and Its Lessons for Chiral Counting  

NASA Astrophysics Data System (ADS)

Chiral Effective Field Theory with explicit ?(1232) degree of freedom is for photon energies up to 300 MeV the tool to accurately determine the proton and neutron polarisabilities from Compton scattering in a model-independent and systematic way. It proves in particular indispensable to understand deuteron Compton scattering at 95 MeV as measured at SAL. Simple consistency arguments derived from nuclear phenomenology lead for the deuteron to the correct Thomson limit, demonstrating gauge-invariance and shedding new light on Weinberg264s proposed power-counting of nuclear forces. In our global analysis of all elastic proton and deuteron Compton scattering up to 150;MeV, we find for the static scalar dipole polarisabilities ?^p=(11.0±1.4stat±0.4sys)x10-4 ;fm^3, ?^p=(2.81.4stat±0.4syst)x10-4;fm^3 for the proton and ?^n=(11.6±1.5stat±0.6syst)x10-4;fm^3 ?^n=(3.61.5stat±0.6syst)x10-4;fm^3 for the neutron. Thus, proton and neutron polarisabilities are identical within the accuracy of available data. New experiments e.g. at MAXlab (Lund) will improve the statistical error-bar. [1] R. P. Hildebrandt, H. W. Grießhammer and T. R. Hemmert, submitted to Phys. Rev. C [nucl-th/0512063]. [2] H. W. Grießhammer: Power-Counting in Chiral EFT from a Minimum of Phenomenology, in preparation.

Griesshammer, Harald W.

2007-10-01

318

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

319

The measurement of trabecular bone mineral density using coherent and Compton scattered photons in vitro.  

PubMed

A photon scattering method for measuring the trabecular bone mineral density (TBMD) in vitro is described. This method involves the measurement of the ratio of coherent to Compton 90 degrees scattered photons from Am-241 by using a narrow beam geometry with an intrinsic germanium detector. The feasibility of using smaller scattering angles for better counting efficiency and the associated problems in their application for in-vivo measurements were investigated. Calibration of the system with fresh trabecular bone samples showed a linear relationship between the coherent to Compton ratio R of the detected counts and the TBMD (r = 0.94). The effect of the overlying soft tissue on the R ratio was significant while the effect of self-attenuation by the trabecular bone itself and the cortical layer was negligible. It was found that the marrow fat content could alter the value of the R ratio. Our results show that for a 10% increase in the fat content in the interstices of the trabecular bone there is a 2.5% decrease in the R ratio. This technique together with soft tissue corrections will enable us to measure the TBMD of the calcaneum in vivo, assuming a small variation in the trabecular fat content. The estimated absorbed dose to the bone marrow is about 139 mrad. PMID:7087905

Ling, S S; Rustgi, S; Karellas, A; Craven, J D; Whiting, J S; Greenfield, M A; Stern, R

320

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

321

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

322

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

323

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

324

Deeply virtual Compton scattering at a proposed high-luminosity Electron-Ion Collider  

NASA Astrophysics Data System (ADS)

Several observables for the deeply virtual Compton scattering process have been simulated in the kinematic regime of a proposed Electron-Ion Collider to explore the possible impact of such measurements for the phenomenological access of generalized parton distributions. In particular, emphasis is given to the transverse distribution of sea quarks and gluons and how such measurements can provide information on the angular momentum sum rule. The exact lepton energy loss dependence for the unpolarized t-differential electroproduction cross section, needed for a Rosenbluth separation, is also reported.

Aschenauer, E. C.; Fazio, S.; Kumeri?ki, K.; Müller, D.

2013-09-01

325

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

2007-04-09

326

Next-to-leading order corrections to timelike, spacelike, and double deeply virtual Compton scattering  

NASA Astrophysics Data System (ADS)

We calculate the O(?s) corrections to the timelike, spacelike, and double deeply virtual Compton scattering amplitudes in the generalized Bjorken scaling region. Special attention is devoted to studies of the difference between the next-to-leading order timelike and spacelike coefficient functions, which plays for this process a role analogous to the large K factor which was much discussed in the analysis of inclusive Drell-Yan cross sections. Also in the present studies the timelike nature of the hard scale gives rise to a new absorptive part of the amplitude and to the presence of characteristic ?2 terms, which can potentially lead to sizable corrections.

Pire, B.; Szymanowski, L.; Wagner, J.

2011-02-01

327

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

328

Deeply virtual Compton scattering on longitudinally polarized protons and neutrons at CLAS  

SciTech Connect

This paper focuses on a measurement of deeply virtual Compton scattering (DVCS) performed at Jefferson Lab using a nearly-6-GeV polarized electron beam, two longitudinally polarized (via DNP) solid targets of protons (NH{sub 3}) and deuterons (ND{sub 3}) and the CEBAF Large Acceptance Spectrometer. Here, preliminary results for target-spin asymmetries and double (beam-target) asymmetries for proton DVCS, as well as a very preliminary extraction of beam-spin asymmetry for neutron DVCS, are presented and linked to Generalized Parton Distributions.

Silvia Niccolai

2012-04-01

329

Photoabsorption and Compton scattering in ionization of helium at high photon energies  

SciTech Connect

Production of singly and doubly charged helium ions by impact of keV photons is studied. The ratio R{sub ph} = {sigma}{sub ph}{sup ++}/{sigma}{sub ph}{sup +} for photoabsorption is calculated in the photon-energy range 2--18 keV using correlated initial- and final- state wave functions. Extrapolation towards asymptotic photon energies yields R{sub ph}({omega} {yields} {infinity}) = 1.66% in agreement with previous predictions. Ionization due to Compton scattering, which becomes comparable to photoabsorption above {omega} {approximately} 3 keV, is discussed.

Andersson, L.R.; Burgdoerfer, J. [Oak Ridge National Lab., TN (United States)]|[Tennessee Univ., Knoxville, TN (United States). Dept. of Physics and Astronomy

1993-10-01

330

Compton ring for nuclear waste management  

NASA Astrophysics Data System (ADS)

This paper describes an intense gamma-ray source based on the Compton scattering of laser photons by the electrons circulating in the storage ring. Gamma-ray energies fall in the range from 1 to 5 MeV. This source is an ideal tool for nuclear waste management by the nuclear resonance fluorescence method. The Compton ring is also a very promising tool for application in novel technologies for express cargo inspection to prevent nuclear terrorism. A crab-crossing scheme in the ring lattice can be expected to permit a gamma-beam intensity of up to 5×1013 gammas/s with the latest laser and accelerator technologies.

Bulyak, Eugene; Gladkikh, Peter; Omori, Tsunehiko; Skomorokhov, Vladislav; Urakawa, Junji

2010-09-01

331

Gamma rays of 1-30 MeV from the Galactic Center Region  

Microsoft Academic Search

Preliminary results are reported for gamma rays from the Galactic Center Region at 1-30 MeV made with a balloon-borne double Compton scatter gamma ray telescope. The Compton scatter angle, energy, and arrival time of the incident gamma ray and direction of the Compton scattered secondary for downward-moving gamma rays were measured. The handling of the data is described, and the

T. Oneill; J. Long; E. Zanrosso; A. Zych; R. S. White; B. Dayton

1983-01-01

332

High energy afterglows and flares from gamma-ray burst by inverse Compton emission  

NASA Astrophysics Data System (ADS)

Aims:We perform a detailed study of inverse Compton (IC) emission for a fireball undergoing external shock (ES) in either a uniform or a wind-like interstellar medium, and assess the relative importance of IC and synchrotron emissions. Methods: We determine the primary model parameters driving the IC to synchrotron emission ratio in the case of a short duration central engine. We then investigate the case of ES by a long duration central engine, or delayed external shock (DES), a model that can account for some of the flares observed in gamma-ray bursts (GRB) X-ray light curves at late times. We present model predictions, in particular in terms of GeV vs. X-ray behavior, and compare them with other models proposed to explain the origin of flares. Results: We find that if most of the emission occurs when the fireball is in the fast cooling regime, then a substantial GeV emission is expected both for a short (standard ES) and a long (DES) duration central engine activity. In particular, in the context of standard ES we are able to account for the delayed emission observed in GRB 940217. In the case of DES, we find that IC scattering of X-ray flare photons can produce high energy flares in the GeV band, which can be detected by the Large Area Telescope aboard GLAST. The detectability of high energy flares improves with the burst kinetic energy E: about 30% of Swift GRBs showing flares in their X-ray light curve have sufficiently large kinetic energy so that the expected high flares can be detected by GLAST. One important prediction of the DES model is the simultaneity between low and high energy flares. To test this simultaneity, the peak energies of both flares need to fall below or within the observational bands. We predict that X-ray flares with peak energy of ~10 eV produce high energy flares with peak energy of around 100 MeV-GeV. Observations by Swift and GLAST then, can test the predicted simultaneity, thus helping to discriminate between different models.

Galli, A.; Piro, L.

2007-11-01

333

POST-PERIASTRON GAMMA-RAY FLARE FROM PSR B1259-63/LS 2883 AS A RESULT OF COMPTONIZATION OF THE COLD PULSAR WIND  

SciTech Connect

We argue that the bright flare of the binary pulsar PSR B1259-63/LS2883 detected by the Fermi Large Area Telescope is due to the inverse Compton scattering of the unshocked electron-positron pulsar wind with a Lorentz factor {Gamma}{sub 0} Almost-Equal-To 10{sup 4}. The combination of two effects both linked to the circumstellar disk (CD) is a key element in the proposed model. The first effect is related to the impact of the surrounding medium on the termination of the pulsar wind. Inside the disk, the 'early' termination of the wind results in suppression of its gamma-ray luminosity. When the pulsar escapes the disk, the conditions for termination of the wind undergo significant changes. This would lead to a dramatic increase of the pulsar wind zone, and thus to the proportional increase of the gamma-ray flux. On the other hand, if the parts of the CD disturbed by the pulsar can supply infrared photons of density high enough for efficient Comptonization of the wind, almost the entire kinetic energy of the pulsar wind would be converted to radiation, thus the gamma-ray luminosity of the wind could approach the level of the pulsar's spin-down luminosity as reported by the Fermi Collaboration.

Khangulyan, Dmitry [Institute of Space and Astronautical Science/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Aharonian, Felix A. [Dublin Institute for Advanced Studies, 31 Fitzwilliam Place, Dublin 2 (Ireland); Bogovalov, Sergey V. [Department of Molecular Physics, National Research Nuclear University (MEPHI), Kashirskoe shosse 31, Moscow 115409 (Russian Federation); Ribo, Marc, E-mail: khangul@astro.isas.jaxa.jp, E-mail: felix.aharonian@dias.ie, E-mail: svbogovalov@mephi.ru, E-mail: mribo@am.ub.es [Departament d'Astronomia i Meteorologia, Institut de Ciences del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E-08028 Barcelona (Spain)

2012-06-10

334

Simulated Performance of the Nuclear Compton Telescope as a Gamma-Ray Polarimeter  

NASA Astrophysics Data System (ADS)

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. NCT is sensitive to polarization in the range 0.2-1 MeV. NCT consists of 3D position-sensitive germanium strip detectors. The ultra-compact design and new technologies allow NCT to achieve high efficiencies with excellent spectral resolution and background reduction. We are currently preparing a balloon flight of the NCT instrument in New Mexico in September 2008. For studying the gamma-ray polarization capability of NCT during the upcoming balloon flight, detailed Monte Carlo simulations of sources predicted to be polarized in the MeV regime (the Crab nebula, Crab pulsar, and gamma-ray bursts) and of the expected background were performed with the MGGPOD suite. The data analysis, including event reconstruction and polarization analysis, was performed by using the Medium Energy Gamma-ray Astronomy library (MEGAlib). Here we present the results of our Crab and gamma-ray burst simulations and discuss the NCT performance as a polarimeter.

Liang, Jau-Shian; Bellm, E. C.; Boggs, S. E.; NCT Collaboration

2008-03-01

335

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

336

First measurement of Z/?* production in compton scattering of quasi-real photons  

NASA Astrophysics Data System (ADS)

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 55 pb-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 Compton scattering has been detected in the hadronic decay channel. Within well defined kinematic bounds, we measure the product of cross-section and Z/?* branching ratio to hadrons to be (0.9+/-0.3+/-0.1) pb for events with a hadronic mass larger than 60 GeV, dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60 GeV, dominated by (e)e?* production, this product is found to be (4.1+/-1.6+/-0.6) pb. Our results agree with the predictions of two Monte Carlo event generators, grc4f and PYTHIA.

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

1998-10-01

337

Compton recoil electron tracking with silicon strip detectors  

SciTech Connect

The application of silicon strip detectors to Compton gamma ray astronomy telescopes is described in this paper. The Silicon Compton Recoil Telescope (SCRT) tracks Compton recoil electrons in silicon strip converters to provide a unique direction for Compton scattered gamma rays above 1 MeV. With strip detectors of modest positional and energy resolutions of 1 mm FWHM and 3% at 662 keV, respectively, 'true imaging' can be achieved to provide an order of magnitude improvement in sensitivity to 1.6 [times] 10[sup [minus] 6] [gamma]/cm[sup 2]-s at 2 MeV. The results of extensive Monte Carlo calculations of recoil electrons traversing multiple layers of 200 micron silicon wafers are presented. Multiple Coulomb scattering of the recoil electron in the silicon wafer of the Compton interaction and the next adjacent wafer is the basic limitation to determining the electron's initial direction.

O'Neill, T.J.; Ait-Ouamer, F.; Schwartz, I.; Tumer, O.T.; White, R.S.; Zych, A.D. (California Univ., Riverside, CA (United States). Inst. of Geophysics and Planetary Physics)

1992-08-01

338

Limits on Production of Narrow Band Photons from Inverse Compton Scattering  

SciTech Connect

In using the inverse Compton scattering (ICS) interaction as a high brilliance, short wavelength radiation source, one collides two beams, one an intense laser, and the other a high charge, short pulse electron beam. In order to maximize the flux of photons from ICS, one must focus both beams strongly, which implies both use of short beams and the existence of large angles in the interaction. One aspect of brilliance is the narrowness of the wavelength band emitted by the source. This paper explores the limits of ICS-based source brilliance based on inherent wavelength broadening effects that arise due to focal angles, laser energy density, and finite laser pulse length effects. It is shown that for a nominal 1% desired bandwidth, that one obtains approximately one scattered photon per electron in a head-on collision geometry.

Rosenzweig, J.; Williams, O. [UCLA Dept. of Physics and Astronomy, 405 Hilgard Ave., Los Angeles, CA 90034 (United States)

2006-11-27

339

Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction  

NASA Astrophysics Data System (ADS)

The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized Hera positron beam scattering off an unpolarized hydrogen target is measured at Hermes. The asymmetry arises from deeply virtual Compton scattering and its interference with the Bethe-Heitler process. Azimuthal amplitudes of the beam-helicity asymmetry are extracted from a data sample consisting of ep ? ep? events with detection of all particles in the final state including the recoiling proton. The installation of a recoil detector, while reducing the acceptance of the experiment, allows the elimination of background from ep ? eN ?? events, which was estimated to contribute an average of about 12% to the signal in previous Hermes publications. The removal of this background from the present data sample is shown to increase the magnitude of the leading asymmetry amplitude by 0 .054 ± 0 .016 to -0 .328 ± 0 .027 (stat .) ± 0 .045 (syst .).

Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Belostotski, S.; Blok, H. P.; Borissov, A.; Bowles, J.; Brodski, I.; Bryzgalov, V.; Burns, J.; Capiluppi, M.; Capitani, G. P.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; De Leo, R.; De Nardo, L.; De Sanctis, E.; Diefenthaler, M.; Di Nezza, P.; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Etzelmüller, E.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Golembiovskaya, M.; Gregor, I. M.; Guler, H.; Hartig, M.; Hasch, D.; Hillenbrand, A.; Hoek, M.; Holler, Y.; Hristova, I.; Ivanilov, A.; Jackson, H. E.; Jo, H. S.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Krauss, B.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Lehmann, I.; Lenisa, P.; Ruiz, A. López; Lorenzon, W.; Lu, S.; Lu, X.; Ma, B.-Q.; Mahon, D.; Makins, N. C. R.; Manaenkov, S. I.; Manfré, L.; Mao, Y.; Marianski, B.; de la Ossa, A. Martinez; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Osborne, A.; Pappalardo, L. L.; Perez-Benito, R.; Petrosyan, A.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubacek, L.; Rubin, J.; Ryckbosch, D.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seitz, B.; Shearer, C.; Shibata, T.-A.; Shutov, V.; Stancari, M.; Statera, M.; Steijger, J. J. M.; Stewart, J.; Taroian, S.; Terkulov, A.; Truty, R.; Trzcinski, A.; Tytgat, M.; Van Haarlem, Y.; Van Hulse, C.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Ye, Z.; Yen, S.; Zagrebelnyy, V.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

2012-10-01

340

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

341

Dispersionstheoretische Rechnungen ueber die Comptonstreuung am Nukleon in der ersten und zweiten Resonanz. (Dispersion theoretical calculations on the Compton scattering on the nucleon in the first and second resonance).  

National Technical Information Service (NTIS)

This paper is dealing with Compton Scattering off protons and neutrons in the first and second resonance. Imaginary parts of invariant amplitudes for Compton Scattering, which are kinematical-singularity free, are calculated with unitarity relations, cons...

T. Coersmeier

1993-01-01

342

Polarization sensitivity and efficiency for a planar-type segmented germanium detector as a Compton polarimeter  

Microsoft Academic Search

We have investigated performance of a planar-type germanium detector with 25 segments as a Compton polarimeter to measure the linear polarization of gamma rays. We considered three different configurations in sampling horizontal and vertical Compton-scattering events for linearly polarized gamma rays incident on the detector. The experimental polarization sensitivity \\/Q, coincidence efficiency ?coin, and figure of merit \\/F for each

J. H. Lee; C. S. Lee

2003-01-01

343

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

NASA Astrophysics Data System (ADS)

Various telescopes including RXTE, INTEGRAL and Suzaku have detected non-thermal X-ray emission in the 10 - 200 keV band from strongly magnetic neutron stars. Inverse Compton scattering, a quantum-electrodynamical process, is believed to be a leading candidate for the production of this intense X-ray radiation. Magnetospheric conditions are such that electrons may well possess ultra-relativistic energies, which lead to attractive simplifications of the cross section. We have recently addressed such a case by developing compact analytic expressions using correct spin-dependent widths and Sokolov & Ternov (ST) basis states, focusing specifically on ground state-to-ground state scattering. However, inverse Compton scattering can cool electrons down to mildly-relativistic energies, necessitating the development of a more general case where the incoming photons acquire nonzero incident angles relative to the field in the rest frame of the electron, and the intermediate state can be excited to arbitrary Landau levels. In this paper, we develop results pertaining to this general case using ST formalism, and treating the plethora of harmonic resonances associated with various cyclotron transitions between Landau states. Four possible scattering modes (parallel-parallel, perpendicular-perpendicular, parallel-perpendicular, and perpendicular-parallel) encapsulate the polarization dependence of the cross section. We present preliminary analytic and numerical investigations of the magnitude of the extra Landau state contributions to obtain the full cross section, and compare these new analytic developments with the spin-averaged cross sections, which we develop in parallel. Results will find application to various neutron star problems, including computation of Eddington luminosities in the magnetospheres of magnetars. We express our gratitude for the generous support of the Michigan Space Grant Consortium, of the National Science Foundation (REU and RUI), and the NASA Astrophysics Theory and Fundamental Program.

Eiles, Matthew; Gonthier, P. L.; Baring, M. G.; Wadiasingh, Z.

2013-04-01

344

Femtosecond laser clocked compact X-band high gradient photoinjector and accelerator for Compton scattering  

NASA Astrophysics Data System (ADS)

High brightness and low emittance electron beams have found application throughout a variety of scientific research. The ability to produce such beams in the MeV range has previously been restricted to National Laboratory size facilities. While these sources have been successful, the reduction in size could provide valuable access for further scientific endeavors. One such application is the production of monochromatic x-rays through Compton scattering with a high intensity laser pulse. These x-rays would be tunable from 10 keV to more than 100 keV. A compact source of synchrotron type radiation capable of installation in medical institutions would be desirable for further investigation. A combination of X-band microwave and vacuum technologies developed at the Stanford Linear Accelerator Center (SLAC) was assembled. The system uses a pair of X-band klystrons. The first provides the microwave drive power for a 5.5 cell RF gun capable of operating with an accelerating gradient of 200 MV/m. Following the RF gun is a 1.05 m linac capable of accelerating the electron bunches to over 60 MeV with an energy spread of less than 1%. Using a novel frequency selection scheme a Titantium:Sapphire femtosecond laser oscillator serves as both the master clock for the microwave components and optical seed for the following amplifiers. This insures the tabletop laser amplifiers are inherently synchronized to the RF sources. A regenerative amplifier provides the first boost in energy. Half of the output is used for producing UV light for photo injection of the RF gun. The other half is sent to a multi-pass amplifier capable of producing 100 mJ pulses compressed to 50 fs for the Compton scattering. This interaction laser is then focused inside the electron beam vacuum system. The final timing between the optical pulses and the electron beam is achieved with a physical delay line placed after the final amplifier compressor. Background Bremsstrahlung radiation due to interception of the electron beam limited initial detection of the Compton x-rays. The first evidence of Compton x-rays was demonstrated through a scan of the time delay between the electron bunch and the optical pulse at the point of collision.

Destefano, Christopher A.

345

Experimental observation of Z-dependence of saturation depth of 0.662 MeV multiply scattered gamma rays  

NASA Astrophysics Data System (ADS)

The gamma photons continue to soften in energy as the number of scatterings increases in the sample having finite dimensions both in depth and lateral dimensions. The number of multiply scattered photons increases with an increase in target thickness and saturates at a particular value of the target thickness known as saturation depth. The present experiment is undertaken to study the effect of atomic number of the target on saturation depth of 0.662 MeV incident gamma photons multiply scattered from targets of various thicknesses. The scattered photons are detected by an HPGe gamma detector placed at 90° to the incident beam direction. We observe that with an increase in target thickness, the number of multiply scattered photons also increases and saturates at a particular value of the target thickness. The saturation depth decreases with increasing atomic number. The double Compton scattered peak is also observed in the experimental spectra.

Singh, Gurvinderjit; Singh, Manpreet; Singh, Bhajan; Sandhu, B. S.

2006-09-01

346

Post-periastron Gamma-Ray Flare from PSR B1259-63/LS 2883 as a Result of Comptonization of the Cold Pulsar Wind  

NASA Astrophysics Data System (ADS)

We argue that the bright flare of the binary pulsar PSR B1259-63/LS2883 detected by the Fermi Large Area Telescope is due to the inverse Compton scattering of the unshocked electron-positron pulsar wind with a Lorentz factor ?0 ? 104. The combination of two effects both linked to the circumstellar disk (CD) is a key element in the proposed model. The first effect is related to the impact of the surrounding medium on the termination of the pulsar wind. Inside the disk, the "early" termination of the wind results in suppression of its gamma-ray luminosity. When the pulsar escapes the disk, the conditions for termination of the wind undergo significant changes. This would lead to a dramatic increase of the pulsar wind zone, and thus to the proportional increase of the gamma-ray flux. On the other hand, if the parts of the CD disturbed by the pulsar can supply infrared photons of density high enough for efficient Comptonization of the wind, almost the entire kinetic energy of the pulsar wind would be converted to radiation, thus the gamma-ray luminosity of the wind could approach the level of the pulsar's spin-down luminosity as reported by the Fermi Collaboration.

Khangulyan, Dmitry; Aharonian, Felix A.; Bogovalov, Sergey V.; Ribó, Marc

2012-06-01

347

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

348

Determination of the Compton suppression efficiency of Ge-BGO detectors in low (gamma)-ray energy region.  

National Technical Information Service (NTIS)

The response function and the rejection factor of Compton suppression gamma spectrometers have been calculated using the Monte Carlo method starting from low energy region (20 keV). Special emphasis has been given to the influence of inactive layers surro...

J. Rak V. B. Brudanin V. G. Egorov V. E. Kovalenko C. Briancon

1993-01-01

349

Beam spin asymmetries in deeply virtual Compton scattering (DVCS) with CLAS at 4.8 GeV  

SciTech Connect

We report measurements of the beam spin asymmetry in deeply virtual Compton scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, 1.0gamma}p) and H(e,e{sup '}{pi}{sup 0}p) events are separated in each (Q{sup 2},x{sub B},t) bin by a fit to the line shape of the H(e,e{sup '}p)X M{sub x}{sup 2} distribution. The validity of the method was studied in detail using experimental and simulated data. It was shown that with the achieved missing mass squared resolution and the available statistics, the separation of DVCS-Bethe-Heitler and {pi}{sup 0} events can reliably be done with less than 5% uncertainty. Also, the Q{sup 2} and t dependences of the sin{phi} moments of the asymmetry are extracted and compared with theoretical calculations.

Gavalian, G. [University of New Hampshire, Durham, New Hampshire 03824-3568 (United States); Old Dominion University, Norfolk, Virginia 23529 (United States); Burkert, V. D.; Elouadrhiri, L.; Stepanyan, S.; Brooks, W. K.; Carman, D. S.; Cords, D.; Degtyarenko, P. V.; Deur, A.; Guo, L.; Gyurjyan, V.; Ito, M. M.; Lukashin, K.; Manak, J. J.; Mecking, B. A.; Mestayer, M. D.; Niczyporuk, B. B.; Nozar, M.; Sharabian, Y. G.; Smith, E. S. [Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606 (United States)] (and others)

2009-09-15

350

Next-to-leading order corrections to timelike, spacelike, and double deeply virtual Compton scattering  

SciTech Connect

We calculate the O({alpha}{sub s}) corrections to the timelike, spacelike, and double deeply virtual Compton scattering amplitudes in the generalized Bjorken scaling region. Special attention is devoted to studies of the difference between the next-to-leading order timelike and spacelike coefficient functions, which plays for this process a role analogous to the large K factor which was much discussed in the analysis of inclusive Drell-Yan cross sections. Also in the present studies the timelike nature of the hard scale gives rise to a new absorptive part of the amplitude and to the presence of characteristic {pi}{sup 2} terms, which can potentially lead to sizable corrections.

Pire, B. [CPHT, Ecole Polytechnique, CNRS, 91128 Palaiseau (France); Szymanowski, L.; Wagner, J. [Soltan Institute for Nuclear Studies, Hoza 69, 00-681 Warsaw (Poland)

2011-02-01

351

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

2006-12-29

352

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 1013photons/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

353

Detection and Localization of Money Bills Concealed Behind Wooden Walls Using Compton Scattering  

SciTech Connect

This work presents a portable device for detecting visually obscured contraband money bills that may be hidden within conventional household walls for the purpose of avoiding confiscation. The device utilizes the Compton backscattering of photons emitted from a collimated {sup 241}Am source. The scattered photons are detected with a thin NaI(Tl) detector, either over a wide field of view for surface scanning of the wall or within a confined view field for depth scanning. The design of the device was optimized for best density contrast and highest count rate for a given source activity. It was shown that the minimum detectable amount of contraband, with >95% confidence level, is 86 paper bills. The contraband was detectable when hidden in household walls made of gyprock or wooden paneling, even when masked by higher density materials such as metallic piping. The device's capability exceeded those of commercially available density-based portable contraband detectors.

Wart, Jason A. van; Hussein, Esam M.A.; Waller, Edward J

2005-05-15

354

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

355

An Overview of Recent Deeply Virtual Compton Scattering Results at HERMES  

NASA Astrophysics Data System (ADS)

We present recently-released HERMES Deeply Virtual Compton Scattering results of Beam-Helicity (formerly Beam-Spin, BSA) and Beam-Charge (BCA) asymmetries from unpo-larised proton, deuteron and selected heavy nuclear gas targets. A new analysis technique utilising the ability of HERA to produce a longitudinally-polarised lepton beam of both charges has been used to simultaneously extract the BSA and BCA amplitudes arising from the DVCS-squared and Interference terms of the total cross section for proton and deuteron data. Results of the Transverse Target-Spin Asymmetry (TTSA) obtained using this technique have been published for transversely-polarised proton data. These extracted asymmetries are presented, integrated over the kinematic acceptance of the HERMES experiment for this interaction, with their dependences on -t, xB and Q2 also shown. The results are compared with asymmetries from a phenomenological model of GPDs based on double distributions.

Mahon, David Francis

2009-12-01

356

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

357

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

358

An Overview of Recent Deeply Virtual Compton Scattering Results at HERMES  

SciTech Connect

We present recently-released HERMES Deeply Virtual Compton Scattering results of Beam-Helicity (formerly Beam-Spin, BSA) and Beam-Charge (BCA) asymmetries from unpo-larised proton, deuteron and selected heavy nuclear gas targets. A new analysis technique utilising the ability of HERA to produce a longitudinally-polarised lepton beam of both charges has been used to simultaneously extract the BSA and BCA amplitudes arising from the DVCS-squared and Interference terms of the total cross section for proton and deuteron data. Results of the Transverse Target-Spin Asymmetry (TTSA) obtained using this technique have been published for transversely-polarised proton data. These extracted asymmetries are presented, integrated over the kinematic acceptance of the HERMES experiment for this interaction, with their dependences on -t, x{sub B} and Q{sup 2} also shown. The results are compared with asymmetries from a phenomenological model of GPDs based on double distributions.

Mahon, David Francis [University of Glasgow, Glasgow, G12 8QQ, Scotland (United Kingdom)

2009-12-17

359

Reggeometry of Deeply Virtual Compton Scattering and Exclusive Vector Meson Production at HERA  

NASA Astrophysics Data System (ADS)

A Reggeometric (Regge+Geometry) model, based on the observed proportionality between the forward slope of the differential cross section and the interaction radius, the latter depending on virtuality Q2 of the incoming virtual photon and on the mass M 2 of the produced particle, is constructed. The objective of this study is the dependence of the Regge-pole amplitude on the virtuality Q2 and masses of the external particles, which remains an open problem for the theory. The present analysis is based on the HERA data on Deeply Virtual Compton Scattering (DVCS) and exclusive diffractive Vector Meson Production (VMP). We treat each class of reactions separately, anticipating a further study that will include both a soft and a hard component of the unique pomeron.

Fazio, S.; Fiore, R.; Lavorini, A.; Jenkovszky, L.; Salii, A.

360

Low-energy Compton scattering and the polarizabilities of the proton  

NASA Astrophysics Data System (ADS)

Differential cross-sections for Compton scattering from the proton have been measured at the MAMI tagged photon facility using the TAPS setup. The data cover an angular range of ?lab? = 59°-155° and photon energies ranging from 55 MeV to 165 MeV. Our results are in good agreement with those from previous experiments, but yield higher precision. Using dispersion relations the proton polarizabilities have been determined to be = [11.9+/-0.5stat.+/-1.3syst.+/-0.3mod.] . 10-4fm3 and = [1.2+/-0.7stat.+/-0.3syst.+/-0.4mod.)] . 10-4fm3. These results confirm the Baldin sum rule which was re-evaluated to be + = [13.8+/-0.4] . 10-4fm3. We can also conclude that there is no significant additional asymptotic contribution to the backward spin polarizability ?? beyond the t-channel ?0-exchange.

Olmos de León, V.; Wissmann, F.; Achenbach, P.; Ahrens, J.; Arends, H.-J.; Beck, R.; Harty, P. D.; Hejny, V.; Jennewein, P.; Kotulla, M.; Krusche, B.; Kuhr, V.; Leukel, R.; McGeorge, J. C.; Metag, V.; Novotny, R.; Polonski, A.; Rambo, F.; Schmidt, A.; Schumacher, M.; Siodlaczek, U.; Ströher, H.; Thomas, A.; Weiß, J.; Wolf, M.

361

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

362

A General Relativistic External Compton-Scattering Model for TeV Emission from M87  

NASA Astrophysics Data System (ADS)

M87 is the first detected non-blazar extragalactic tera-electron-volt (TeV) source with rapid variation and a very flat spectrum in the TeV band. To explain the two peaks in the spectral energy distribution of the nucleus of M87, which is similar to that of blazars, the most commonly adopted models are the synchrotron self-Compton-scattering models and the external inverse Compton (EIC) scattering models. Considering that there is no correlated variation in the soft band (from radio to X-ray) matching the TeV variation and that the TeV sources should not suffer from ?? absorption due to the flat TeV spectrum, the EIC models are advantageous in modeling the TeV emission from M87. In this paper, we propose a self-consistent EIC model to explain the flat TeV spectrum of M87 within the framework of fully general relativity, where the background soft photons are from the advection-dominated accretion flow around the central black hole, and the high-energy electrons are from the mini-jets that are powered by the magnetic reconnection in the main jet. In our model, both the TeV flares observed in the years 2005 and 2008 could be well explained: the ?? absorption for TeV photons is very low, even inside the region very close to the black hole 20Rg ~ 50Rg ; at the same region, the average EIC cooling time (~102 ~ 103 s) is short, which is consistent with the observed timescale of the TeV variation. Furthermore, we also discuss the possibility that the accompanying X-ray flare in 2008 is due to the direct synchrotron radiation of the mini-jets.

Cui, Yu-Dong; Yuan, Ye-Fei; Li, Yan-Rong; Wang, Jian-Min

2012-02-01

363

New sum rules from low energy Compton scattering on arbitrary spin target  

NASA Astrophysics Data System (ADS)

We derive two sum rules by studying the low energy Compton scattering on a target of arbitrary (nonzero) spin j. In the first sum rule, we consider the possibility that the intermediate state in the scattering can have spin | j±1| and the same mass as the target. The second sum rule applies if the theory at hand possesses intermediate narrow resonances with masses different from the mass of the scatterer. These sum rules are generalizations of the Gerasimov-Drell-Hearn-Weinberg sum rule. Along with the requirement of tree level unitarity, they relate different low energy couplings in the theory. Using these sum rules, we show that in certain cases the gyromagnetic ratio can differ from the "natural" value g = 2, even at tree level, without spoiling perturbative unitarity. These sum rules can be used as constraints applicable to all supergravity and higher-spin theories that contain particles charged under some U(1) gauge field. In particular, applied to four dimensional N = 8 supergravity in a spontaneously broken phase, these sum rules suggest that for the theory to have a good ultraviolet behavior, additional massive states need to be present, such as those coming from the embedding of the N = 8 supergravity in type II superstring theory. We also discuss the possible implications of the sum rules for QCD in the large- N c limit.

Grigoryan, Hovhannes R.; Porrati, Massimo

2012-07-01

364

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

SciTech Connect

The proton structure function F2 is measured using inelastic QED Compton events. The data were collected by H1 experiment at the HERA in 1997 and correspond to a luminosity of 9.25 pb-1. QED Compton events allow to access very low Q2 region, down to 0.5 GeV2 and Bjorken x up to {approx} 0.06, a region that has not been covered by previous inclusive measurements at HERA. The results are in agreement with measurements from fixed targed lepton-nucleon scattering experiments.

Lobodzinska, Ewelina Maria [DESY, Zeuthen (Germany); INP, Cracow (Poland)

2005-10-06

365

A Ge-NaI(Tl) spectrometer with Compton suppression and gamma coincidence counting. Application to 189Ir and 101Rh activity measurements  

Microsoft Academic Search

This article presents the characteristics of a spectrometer consisting of a Ge detector surrounded by a NaI(Tl) detector that can operate in Compton-suppression and gamma-gamma coincidence modes. The criteria that led to this measurement configuration are discussed and the spectrometer performances are shown for 60Co and 137Cs gamma-ray sources. The results for the measurement of 189Ir (Compton suppression) and for

D. Massé; A. Adam; J. Laurec

1991-01-01

366

Inverse-Compton cooling in Klein-Nishina regime and gamma-ray burst prompt spectrum  

NASA Astrophysics Data System (ADS)

Synchrotron radiation mechanism, when electrons are accelerated in a relativistic shock, is known to have serious problems in explaining the observed gamma-ray spectrum below the peak for most gamma-ray bursts (GRBs); the synchrotron spectrum below the peak is much softer than observed spectra. Recently, the possibility that electrons responsible for the radiation cool via inverse Compton, but in the Klein-Nishina regime, has been proposed as a solution to this problem. We provide an analytical study of this effect and show that it leads to a hardening of the low-energy spectrum but not enough to make it consistent with the observed spectra for most GRBs (this is assuming that electrons are injected continuously over a time-scale comparable to the dynamical time-scale, as is expected for internal shocks of GRBs). In particular, we find that it is not possible to obtain a spectrum with ? > -0.1 (f? ? ??), where the typical observed value is ? ˜ 0. Moreover, extreme values for a number of parameters are required in order that ? ˜ -0.1: the energy fraction in magnetic field needs to be less than about 10-4, the thermal Lorentz factor of electrons should be larger than 106 and the radius where gamma-rays are produced should be not too far away from the deceleration radius. These difficulties suggest that the synchrotron radiation mechanism in internal shocks does not provide a self-consistent solution when ? ? -0.2.

Barniol Duran, R.; Bošnjak, Ž.; Kumar, P.

2012-08-01

367

Expected Sensitivity of the Nuclear Compton Telescope to Gamma-Ray Line Emission  

NASA Astrophysics Data System (ADS)

The Nuclear Compton Telescope (NCT) is a balloon-borne soft gamma-ray (0.2-10 MeV) telescope designed to study astrophysical sources of nuclear line emission and gamma-ray polarization. NCT consists of twelve 3D position-sensitive germanium strip detectors. The ultra-compact design and new technologies allow NCT to achieve high efficiency with excellent spectral resolution and background reduction. We are currently preparing for a conventional balloon flight ( 36 hr) of the NCT instrument from New Mexico in September 2008 and a long-duration balloon flight (LDBF) ( 20 days) from Australia in December 2009. Here we focus on the LDBF in 2009. Our source and background simulations are performed using the Monte Carlo simulation package MGGPOD, and events are reconstructed using the Medium Energy Gamma-ray Astronomy library (MEGAlib). We use the same tools that were successfully used for background simulations of the 2005 prototype flight (see J. Bowen, this conference). Sensitivity is optimized using standard cuts such as photon energy, angular resolution measure (ARM), and event quality factor. In this work, we present realistic line sensitivities for NCT for the LDBF in 2009.

Chiu, Jeng-Lun; Bandstra, M. E.; Boggs, S. E.; NCT Collaboration

2008-03-01

368

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

NASA Astrophysics Data System (ADS)

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.

1992-02-01

369

Magnetism of CaRu{sub 1-x}Mn{sub x}O{sub 3}: Magnetic Compton scattering study  

SciTech Connect

The magnetism of CaRu{sub 1-x}Mn{sub x}O{sub 3} was studied using magnetic Compton scattering measurements for polycrystalline specimens at 10 K under 2.5 T using a synchrotron-radiation x ray. The spin moment deduced from the magnetic Compton profiles has a maximum at x=0.7 and the value agrees with the result of the magnetization measurement. The magnetic Compton profiles indicate that the Mn spin moment is dominant in magnetization and that Ru moment, which is induced with Mn doping, couples with Mn spin moment antiferromagnetically. The results suggest that a sort of ferrimagnetism is established in the CaRu{sub 1-x}Mn{sub x}O{sub 3} system.

Mizusaki, S.; Taniguchi, T.; Okada, N.; Nagata, Y. [College of Science and Engineering, Aoyama Gakuin University, Fuchinobe, Sagamihara, Kanagawa 157-8572 (Japan); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute (JASRI/Spring-8), Sayo, Mikazuki, Hyogo 679-5198 (Japan); Ozawa, T. C. [Nanoscale Materials Center, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044 (Japan); Noro, Y. [Kawazoe Frontier Technologies, Co., Ltd., Kuden, Sakae, Yokohama, Kanagawa 931-113 (Japan); Samata, H. [Faculty of Maritime Sciences, Kobe University, Fukaeminami, Higashinada, Kobe, Hyogo 658-0022 (Japan)

2008-04-01

370

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

371

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

372

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

373

Using Effective Field Theory to analyse low-energy Compton scattering data from protons and light nuclei  

NASA Astrophysics Data System (ADS)

Compton scattering from protons and neutrons provides important insight into the structure of the nucleon. For photon energies up to about 300 MeV, the process can be parameterised by six dynamical dipole polarisabilities which characterise the response of the nucleon to a monochromatic photon of fixed frequency and multipolarity. Their zero-energy limit yields the well-known static electric and magnetic dipole polarisabilities ? and ?, and the four dipole spin polarisabilities. The emergence of full lattice QCD results and new experiments at MAMI (Mainz), HI?S at TUNL, and MAX-Lab (Lund) makes this an opportune time to review nucleon Compton scattering. Chiral Effective Field Theory (?EFT) provides an ideal analysis tool, since it encodes the well-established low-energy dynamics of QCD while maintaining an appropriately flexible form for the Compton amplitudes of the nucleon. The same ?EFT also describes deuteron and 3He Compton scattering, using consistent nuclear currents, rescattering and wave functions, and respects the low-energy theorems for photon-nucleus scattering. It can thus also be used to extract useful information on the neutron amplitude from Compton scattering on light nuclei. We summarise past work in ?EFT on all of these reactions and compare with other theoretical approaches. We also discuss all proton experiments up to about 400 MeV, as well as the three modern elastic deuteron data sets, paying particular attention to the precision and accuracy of each set. Constraining the ?(1232) parameters from the resonance region, we then perform new fits to the proton data up to ?=170MeV, and a new fit to the deuteron data. After checking in each case that a two-parameter fit is compatible with the respective Baldin sum rules, we obtain, using the sum-rule constraints in a one-parameter fit, ?E1(p)=10.7±0.3(stat)±0.2(Baldin)±0.8(theory), ?M1(p)=3.1?0.3(stat)±0.2(Baldin)±0.8(theory), for the proton polarisabilities, and ?E1(s)=10.9±0.9(stat)±0.2(Baldin)±0.8(theory), ?M1(s)=3.6?0.9(stat)±0.2(Baldin)±0.8(theory), for the isoscalar polarisabilities, each in units of 10-4fm. Finally, we discuss plans for polarised Compton scattering on the proton, deuteron, 3He and heavier targets, their promise as tools to access spin polarisabilities, and other future avenues for theoretical and experimental investigation.

Grießhammer, H. W.; McGovern, J. A.; Phillips, D. R.; Feldman, G.

2012-10-01

374

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

375

Propagation of gamma-rays at cosmological redshifts  

Microsoft Academic Search

We discuss absorption and reprocessing of gamma-rays at cosmological redshifts. We consider Compton scattering and pair production by gamma-rays on the cosmic baryonic matter, and photon-photon scattering and photon-photon pair production by gamma-rays and Compton scattering of relativistic pairs on the cosmic blackbody background. We point out the cosmological importance of photon-photon scattering (a process not previously considered in astrophysics).

Andrzej A. Zdziarski; Roland Svensson

1989-01-01

376

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

377

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 deg 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 arcmin^2, and only four have areas greater than 1 deg^2. The area of the smallest box is 0.44 arcmin^2. 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

378

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

NASA Astrophysics Data System (ADS)

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 and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year.

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

2004-12-01

379

Corrections for the effects of accidental coincidences, Compton scatter, and object size in positron emission mammography (PEM) imaging  

SciTech Connect

Positron emission mammography (PEM) has begun to show promise as an effective method for the detection of breast lesions. Due to its utilization of tumor-avid radiopharmaceuticals labeled with positron-emitting radionuclides, this technique may be especially useful in imaging of women with radiodense or fibrocystic breasts. While the use of these radiotracers affords PEM unique capabilities, it also introduces some limitations. Specifically, acceptance of accidental and Compton-scattered coincidence events can decrease lesion detectability. The authors studied the effect of accidental coincidence events on PEM images produced by the presence of 18F-Fluorodeoxyglucose in the organs of a subject using an anthropomorphic phantom. A delayed-coincidence technique was tested as a method for correcting PEM images for the occurrence of accidental events. Also, a Compton scatter correction algorithm designed specifically for PEM was developed and tested using a compressed breast phantom.

Raymond Raylman; Stanislaw Majewski; Randolph Wojcik; Andrew Weisenberger; Brian Kross; Vladimir Popov

2001-06-01

380

The effect of filters and collimators on Compton scatter and Pb K-series peaks in XRF bone lead analysis  

NASA Astrophysics Data System (ADS)

The utility of Al, Cu and In filters and collimators of different diameters in the X-ray fluorescence measurement of lead in the bone was investigated. The changes in Compton scattering and Pb K-series peaks were analyzed with different filters and collimators. Compton scattering and fractional dead time were significantly reduced with the use of filters. The FWHM values of Pb K?1, K?1,3 peaks decrease in a nearly linear relation with the ratio of length of collimator to the diameter as the small diameter collimator with long length reduces divergence of spectra, thus improves resolution. The measurement precisions of K?1 and K?1,3 peaks were improved by applying an indium filter. The ratio of signal-to-noise slightly increases when an indium filter was used.

Luo, Liqiang; Chettle, David R.; Nie, Huiling; McNeill, Fiona E.; Popovic, Marija

2007-10-01

381

Measurements of Rayleigh, Compton and resonant Raman scattering cross-sections for 59.536 keV ?-rays  

NASA Astrophysics Data System (ADS)

The K-L and K-M resonant Raman scattering (RRS) cross-sections have been measured for the first time at the 59.536 keV photon energy in the 70Yb (BK=61.332 keV), 71Lu (BK=63.316 keV) and 72Hf (BK=65.345 keV) elements; BK being the K-shell binding energy. The K-L and K-M RRS measurements have been performed at the 59° and 133° angles, respectively, to avoid interference of the Compton-scatter peak. The Rayleigh and Compton scattering cross-sections for the 59.536 keV ?-rays have also been measured at both the angles in the atomic region 1<=Z<=92. Measurements were performed using the reflection-mode geometrical arrangements involving the 241Am radioisotope as photon source and planar Si(Li) and HPGe detectors. Ratios of the K-M and K-L RRS cross-sections in Yb, Lu and Hf are in general lower than that of the fluorescent K?1,3,5 (K-M) and K? (K-L) X-ray transition probabilities. Theoretical Rayleigh scattering cross-sections based on the modified form-factors (MFs) corrected for the anomalous scattering factors (ASFs) and the S-matrix calculations are on an average ~15% and ~6% higher, respectively, at the 133° angle and exhibit good agreement with the measured data at the 59° angle. Larger deviations ~30% and ~20%, respectively, are observed at the 133° angle for the 64Gd, 66Dy, 67Ho and 70Yb elements having the K-shell binding energy in vicinity of the incident photon energy. The measured Compton scattering cross-sections are in general agreement with those calculated using the Klein-Nishina cross-sections and the incoherent scattering function.

Singh, Prem; Mehta, D.; Singh, N.; Puri, S.; Shahi, J. S.

2004-09-01

382

Development of the Goddard Compton gamma-ray telescope and neutral hydrogen observations towards the Puppis window of the Galaxy. (Volumes I and II)  

Microsoft Academic Search

The dissertation is composed of two parts, each treating a separate topic of current interest in astronomy. In Part One, the development of a new instrument designed to conduct balloon-borne observations in the medium energy gamma ray (..gamma..-ray) region is described. Based on the Compton coincidence principle, the NASA\\/Goddard Advanced Compton Telescope (ACT) is intended for the study of point

1986-01-01

383

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

SciTech Connect

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. [Department of Physics and Astronomy, Tufts University, Medford, Massachusetts 02155 (United States); Liuti, Simonetta [Department of Physics, University of Virginia, Charlottesville, Virginia 22901 (United States)

2009-10-01

384

Determination of Circular Polarization of gamma-quanta with Energy > 10 MeV using Compton Polarimeter  

Microsoft Academic Search

The circularly polarized gamma-quanta with energy > 10 MeV are formed during Compton backscattering of circularly polarized laser photons on an electron beam with energy 1.26 GeV. The contribution of nonlinear processes for planned parameters of a laser flash[T. Okugi, Y. Kurihara and M. Chiba, Jpn. J. Appl. Phys. 35, p. 3677 (1996).] can be rather significant, that leads to

A. S. Arychev; A. P. Potylitsyn; M. N. Strikhanov

2001-01-01

385

SCATTERING OF GAMMA RAYS BY A STATIC ELECTRIC FIELD  

Microsoft Academic Search

In an effort to observe Delbruck scattering the absolute differential ; cross sections for the elastic scattering of 1.33-Mev gamma rays by lead, tin, ; and uranium and of 2.62-Mev gamma rays by lead and tin have been measured for ; angles between 15 and 105 degrees. The observed scattering is the coherent sum ; of Delbruck, Rayleigh, and nuclear

A. M. Bernstein; A. K. Mann

1958-01-01

386

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

387

Second order formalism for spin (1/2) fermions and Compton scattering  

SciTech Connect

We develop a second order formalism for massive spin 1/2 fermions based on the projection over Poincare invariant subspaces in the ((1/2),0)+(0,(1/2)) representation of the homogeneous Lorentz group. Using the U(1){sub em} gauge principle we obtain a second order description for the electromagnetic interactions of a spin 1/2 fermion with two free parameters, the gyromagnetic factor g and a parameter {xi} related to odd-parity Lorentz structures. We calculate Compton scattering in this formalism. In the particular case g=2, {xi}=0, and for states with well-defined parity, we recover Dirac results. In general, we find the correct classical limit and a finite value r{sub c}{sup 2} for the forward differential cross section, independent of the photon energy and of the value of the parameters g and {xi}. The differential cross section vanishes at high energies for all g, {xi} except in the forward direction. The total cross section at high energies vanishes only for g=2, {xi}=0. We argue that this formalism is more convenient than Dirac theory in the description of low energy electromagnetic properties of baryons and illustrate the point with the proton case.

Delgado-Acosta, E. G.; Napsuciale, Mauro; Rodriguez, Simon [Departamento de Fisica, Universidad de Guanajuato, Lomas del Bosque 103, Fraccionamiento Lomas del Campestre, C.P. 37150, Leon, Guanajuato (Mexico); Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Coahuila, Edificio 'D', Unidad Camporredondo, CP 25280, Saltillo, Coahuila (Mexico)

2011-04-01

388

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

389

Nucleon polarisabilities from Compton scattering off the one- and few-nucleon system  

NASA Astrophysics Data System (ADS)

These proceedings sketch how combining recent theoretical advances with data from the new generation of high-precision Compton scattering experiments on both the proton and few-nucleon systems offers fresh, detailed insight into the Physics of the nucleon polarisabilities. A multipole-analysis is presented to simplify their interpretation. Predictions from Chiral Effective Field Theory with special emphasis on the spin-polarisabilities can serve as a guideline for doubly-polarised experiments below 300 MeV. The strong energy-dependence of the scalar magnetic dipole-polarisability ? turns out to be crucial to understanding the proton and deuteron data. Finally, a high-accuracy determination of the proton and neutron polarisabilities shows that they are identical within error-bars. For details and a better list of references, consult Refs. [H.W. Grießhammer, T.R. Hemmert, Phys. Rev. C 65 (2002) 045207, nucl-th/0110006; R.P. Hildebrandt, H.W. Grießhammer, T.R. Hemmert, B. Pasquini, Eur. Phys. J. A 20 (2004) 293, nucl-th/0307070; R.P. Hildebrandt, H.W. Grießhammer, T.R. Hemmert, Eur. Phys. J. A 20 (2004) 329, nucl-th/0308054; R.P. Hildebrandt, H.W. Grießhammer, T.R. Hemmert, D.R. Phillips, Eur. Phys. J. A, nucl-th/0405077 (in press)].

Grießhammer, Harald W.

2005-07-01

390

Measurement of electron beam polarization from the energy asymmetry of Compton scattered photons  

SciTech Connect

The authors describe a new method for precision measurement ({approximately} 1%) of the longitudinal polarization of high-energy electron beams. The method relies on measuring the energy asymmetry of Compton scattered photons which result from collisions between the electron beam and a polarized laser beam. The measurement takes place near the electron-positron interaction point at the SLAC Linear Collider (SLC). The detector described here (PGC) is a threshold gas Cherenkov device which follows a lead radiator. The Cherenkov threshold (14 MeV) is essential for eliminating enormous synchrotron radiation-induced backgrounds at the position of interest in the SLC. They also describe the calibration of the PGC energy response in a test beam and its performance as a working polarimeter for the SLC/SLD physics program. Preliminary results from the 1996 run indicate that PGC measurement with total error at or below the 1% level is indeed achievable, and hence serves as a valuable crosscheck of the polarization scale.

Field, R.C.; Woods, M.; Zhou, J. [Stanford Linear Accelerator Center, CA (United States); Frey, R.; Arodzero, A. [Univ. of Oregon, Eugene, OR (United States). Physics Dept.

1998-06-01

391

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

392

Determination of Vanadium by Instrumental Neutron Activation Analysis in Conjunction with Compton Suppression Gamma-Ray Spectrometry  

SciTech Connect

The toxicity of vanadium has been known for a long time. It is only recently that vanadium has been recognized as an essential trace element. The determination of vanadium with high precision and accuracy in tissues, foods, and other biological materials is needed for the purpose of studying its effect on human nutrition and health. Several techniques such as spectrophotometry, atomic absorption, X-ray fluorescence, and neutron activation analysis (NAA) can be used for its determination. Vanadium can be determined by NAA through its short-lived nuclide {sup 52}V produced via the {sup 51}V(n, {gamma}){sup 52}V reaction; it has a 1434.2-keV gamma ray and a half-life of 3.74 min. It has been reported that {sup 52}V has sufficient sensitivity for its measurement down to nanogram levels. However, it is seldom assayed in practice by instrumental NAA (INAA) in conjunction with conventional gamma-ray spectrometry, in particular for low vanadium content in high-salt biological materials, due to the Compton background interference from nuclides such as {sup 28}Al, {sup 38}Cl, {sup 56}Mn, and {sup 24}Na. Alternatively, radiochemical NAA or preconcentration NAA methods are used to separate vanadium from the major and interfering elements. A Compton suppression counting technique can be beneficially used under such situations. One of the objectives of this work was to fully explore the advantages of Compton suppression counting for the determination of vanadium in biological samples.

W. H. Zhang; A. Chatt

2000-11-12

393

Efficient propagation of polarization from laser photons to positrons through compton scattering and electron-positron pair creation.  

PubMed

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 2 x 10(4) e+ /bunch. The magnitude of positron polarization has been determined to be 73 +/- 15(stat) +/- 19(syst)% by means of a newly designed positron polarimeter. PMID:16605830

Omori, T; Fukuda, M; Hirose, T; Kurihara, Y; Kuroda, R; Nomura, M; Ohashi, A; Okugi, T; Sakaue, K; Saito, T; Urakawa, J; Washio, M; Yamazaki, I

2006-03-24

394

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

395

A Fast Scintillator Compton Telescope for Medium-Energy Gamma-Ray Astronomy  

NASA Astrophysics Data System (ADS)

The field of medium-energy gamma-ray astronomy urgently needs a new mission to build on the success of the COMPTEL instrument. This mission must achieve a sensitivity significantly greater than that of COMPTEL in order to advance the science of relativistic particle accelerators, nuclear astrophysics, and diffuse backgrounds and bridge the gap between current and future hard X-ray missions and the high-energy Fermi mission. Such an increase in sensitivity can only come about via a dramatic decrease in the instrumental background. We are currently developing a concept for a low-background Compton telescope that employs modern scintillator technology to achieve this increase in sensitivity. Specifically, by employing Lanthanum Bromide scintillators for the calorimeter, one can take advantage of the unique speed and resolving power of this material to improve the instrument sensitivity and simultaneously enhance its spectroscopic performance and thus its imaging performance. We present the design and calibration results of a small prototype of such an instrument, scheduled to fly on a balloon test flight in the Fall of 2011. We discuss the expected results from this test flight and the expected sensitivity of a full-scale instrument on a long-duration balloon mission.

Bloser, Peter F.; Ryan, J. M.; Julien, M.; Legere, J. S.; McConnell, M. L.; Kippen, R. M.; Tornga, S.; Wallace, M.

2011-05-01

396

Inverse Compton Origin of the Hard X-ray and Soft gamma-ray Emission from the Galactic Ridge  

SciTech Connect

A recent re-determination of the non-thermal component of the hard X-ray to soft {gamma}-ray emission from the Galactic ridge, using the SPI instrument on the INTErnational Gamma-Ray Astrophysics Laboratory (INTEGRAL) Observatory, is shown to be well reproduced as inverse-Compton emission from the interstellar medium. Both cosmic-ray primary electrons and secondary electrons and positrons contribute to the emission. The prediction uses the GALPROP model and includes a new calculation of the interstellar radiation field. This may solve a long-standing mystery of the origin of this emission, and potentially opens a new window on Galactic cosmic rays.

Porter, Troy A.; Moskalenko, Igor V.; Strong, Andrew W.; Orlando, Elena; Bouchet, Laurent

2008-09-30

397

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

398

Recent developments in nuclear scattering of capture gamma-rays  

SciTech Connect

Recent studies at the IRR-2 reactor using monoenergetic neutron capture ..gamma..-rays fall into three categories: 1) study the low energy GDR tail using the (..gamma.., ..gamma..) and (..gamma.., n) reactions; 2) study of interference effects between nuclear resonance fluorescence, Rayleigh and Delbruck scattering at small angles; 3) testing the 2D absorption structure of simple molecules on graphite using nuclear resonance scattering technique.

Shahal, O.; Moreh, R.

1985-01-15

399

Material efficiency studies for a Compton camera designed to measure characteristic prompt gamma rays emitted during proton beam radiotherapy.  

PubMed

Prompt gamma rays emitted from biological tissues during proton irradiation carry dosimetric and spectroscopic information that can assist with treatment verification and provide an indication of the biological response of the irradiated tissues. Compton cameras are capable of determining the origin and energy of gamma rays. However, prompt gamma monitoring during proton therapy requires new Compton camera designs that perform well at the high gamma energies produced when tissues are bombarded with therapeutic protons. In this study we optimize the materials and geometry of a three-stage Compton camera for prompt gamma detection and calculate the theoretical efficiency of such a detector. The materials evaluated in this study include germanium, bismuth germanate (BGO), NaI, xenon, silicon and lanthanum bromide (LaBr(3)). For each material, the dimensions of each detector stage were optimized to produce the maximum number of relevant interactions. These results were used to predict the efficiency of various multi-material cameras. The theoretical detection efficiencies of the most promising multi-material cameras were then calculated for the photons emitted from a tissue-equivalent phantom irradiated by therapeutic proton beams ranging from 50 to 250 MeV. The optimized detector stages had a lateral extent of 10 × 10 cm(2) with the thickness of the initial two stages dependent on the detector material. The thickness of the third stage was fixed at 10 cm regardless of material. The most efficient single-material cameras were composed of germanium (3 cm) and BGO (2.5 cm). These cameras exhibited efficiencies of 1.15 × 10(-4) and 9.58 × 10(-5) per incident proton, respectively. The most efficient multi-material camera design consisted of two initial stages of germanium (3 cm) and a final stage of BGO, resulting in a theoretical efficiency of 1.26 × 10(-4) per incident proton. PMID:21508442

Robertson, Daniel; Polf, Jerimy C; Peterson, Steve W; Gillin, Michael T; Beddar, Sam

2011-04-20

400

Material efficiency studies for a Compton camera designed to measure characteristic prompt gamma rays emitted during proton beam radiotherapy  

NASA Astrophysics Data System (ADS)

Prompt gamma rays emitted from biological tissues during proton irradiation carry dosimetric and spectroscopic information that can assist with treatment verification and provide an indication of the biological response of the irradiated tissues. Compton cameras are capable of determining the origin and energy of gamma rays. However, prompt gamma monitoring during proton therapy requires new Compton camera designs that perform well at the high gamma energies produced when tissues are bombarded with therapeutic protons. In this study we optimize the materials and geometry of a three-stage Compton camera for prompt gamma detection and calculate the theoretical efficiency of such a detector. The materials evaluated in this study include germanium, bismuth germanate (BGO), NaI, xenon, silicon and lanthanum bromide (LaBr3). For each material, the dimensions of each detector stage were optimized to produce the maximum number of relevant interactions. These results were used to predict the efficiency of various multi-material cameras. The theoretical detection efficiencies of the most promising multi-material cameras were then calculated for the photons emitted from a tissue-equivalent phantom irradiated by therapeutic proton beams ranging from 50 to 250 MeV. The optimized detector stages had a lateral extent of 10 × 10 cm2 with the thickness of the initial two stages dependent on the detector material. The thickness of the third stage was fixed at 10 cm regardless of material. The most efficient single-material cameras were composed of germanium (3 cm) and BGO (2.5 cm). These cameras exhibited efficiencies of 1.15 × 10-4 and 9.58 × 10-5 per incident proton, respectively. The most efficient multi-material camera design consisted of two initial stages of germanium (3 cm) and a final stage of BGO, resulting in a theoretical efficiency of 1.26 × 10-4 per incident proton.

Robertson, Daniel; Polf, Jerimy C.; Peterson, Steve W.; Gillin, Michael T.; Beddar, Sam

2011-05-01

401

Material efficiency studies for a Compton camera designed to measure characteristic prompt gamma rays emitted during proton beam radiotherapy  

PubMed Central

Prompt gamma rays emitted from biological tissues during proton irradiation carry dosimetric and spectroscopic information that can assist with treatment verification and provide an indication of the biological response of the irradiated tissues. Compton cameras are capable of determining the origin and energy of gamma rays. However, prompt gamma monitoring during proton therapy requires new Compton camera designs that perform well at the high gamma energies produced when tissues are bombarded with therapeutic protons. In this study we optimize the materials and geometry of a three-stage Compton camera for prompt gamma detection and calculate the theoretical efficiency of such a detector. The materials evaluated in this study include germanium, bismuth germanate (BGO), NaI, xenon, silicon and lanthanum bromide (LaBr3). For each material, the dimensions of each detector stage were optimized to produce the maximum number of relevant interactions. These results were used to predict the efficiency of various multi-material cameras. The theoretical detection efficiencies of the most promising multi-material cameras were then calculated for the photons emitted from a tissue-equivalent phantom irradiated by therapeutic proton beams ranging from 50 to 250 MeV. The optimized detector stages had a lateral extent of 10 × 10 cm2 with the thickness of the initial two stages dependent on the detector material. The thickness of the third stage was fixed at 10 cm regardless of material. The most efficient single-material cameras were composed of germanium (3 cm) and BGO (2.5 cm). These cameras exhibited efficiencies of 1.15 × 10?4 and 9.58 × 10?5 per incident proton, respectively. The most efficient multi-material camera design consisted of two initial stages of germanium (3 cm) and a final stage of BGO, resulting in a theoretical efficiency of 1.26 × 10?4 per incident proton.

Robertson, Daniel; Polf, Jerimy C; Peterson, Steve W; Gillin, Michael T; Beddar, Sam

2011-01-01

402

Measurement of double-spin asymmetries associated with deeply virtual Compton scattering on a transversely polarized hydrogen target  

NASA Astrophysics Data System (ADS)

Double-spin asymmetries in exclusive electroproduction of real photons from a transversely polarized hydrogen target are measured with respect to the product of target polarization with beam helicity and beam charge, and with respect to the product of target polarization with beam helicity alone. The asymmetries arise from the deeply virtual Compton scattering process and its interference with the Bethe-Heitler process. They are related to the real part of the same combination of Compton form factors as that determining the previously published transverse target single-spin asymmetries through the imaginary part. The results for the double-spin asymmetries are found to be compatible with zero within the uncertainties of the measurement, and are not incompatible with the predictions of the only available GPD-based calculation.

HERMES Collaboration; Airapetian, A.; Akopov, N.; Akopov, Z.; Aschenauer, E. C.; Augustyniak, W.; Avakian, R.; Avetissian, A.; Avetisyan, E.; Belostotski, S.; Bianchi, N.; Blok, H. P.; Borissov, A.; Bowles, J.; Brodski, I.; Bryzgalov, V.; Burns, J.; Capiluppi, M.; Capitani, G. P.; Cisbani, E.; Ciullo, G.; Contalbrigo, M.; Dalpiaz, P. F.; Deconinck, W.; de Leo, R.; de Nardo, L.; de Sanctis, E.; di Nezza, P.; Düren, M.; Ehrenfried, M.; Elbakian, G.; Ellinghaus, F.; Fabbri, R.; Fantoni, A.; Felawka, L.; Frullani, S.; Gabbert, D.; Gapienko, G.; Gapienko, V.; Garibaldi, F.; Gavrilov, G.; Gharibyan, V.; Giordano, F.; Gliske, S.; Golembiovskaya, M.; Hartig, M.; Hasch, D.; Hoek, M.; Holler, Y.; Hristova, I.; Imazu, Y.; Ivanilov, A.; Jackson, H. E.; Jo, H. S.; Joosten, S.; Kaiser, R.; Karyan, G.; Keri, T.; Kinney, E.; Kisselev, A.; Korotkov, V.; Kozlov, V.; Kravchenko, P.; Krivokhijine, V. G.; Lagamba, L.; Lapikás, L.; Lehmann, I.; Lenisa, P.; López Ruiz, A.; Lorenzon, W.; Lu, X.-G.; Lu, X.-R.; Ma, B.-Q.; Mahon, D.; Makins, N. C. R.; Manaenkov, S. I.; Manfré, L.; Mao, Y.; Marianski, B.; Martinez de La Ossa, A.; Marukyan, H.; Miller, C. A.; Miyachi, Y.; Movsisyan, A.; Murray, M.; Mussgiller, A.; Nappi, E.; Naryshkin, Y.; Nass, A.; Negodaev, M.; Nowak, W.-D.; Pappalardo, L. L.; Perez-Benito, R.; Raithel, M.; Reimer, P. E.; Reolon, A. R.; Riedl, C.; Rith, K.; Rosner, G.; Rostomyan, A.; Rubin, J.; Ryckbosch, D.; Salomatin, Y.; Schäfer, A.; Schnell, G.; Schüler, K. P.; Seitz, B.; Shibata, T.-A.; Shutov, V.; Stancari, M.; Statera, M.; Steffens, E.; Steijger, J. J. M.; Stinzing, F.; Taroian, S.; Terkulov, A.; Truty, R.; Trzcinski, A.; Tytgat, M.; van Haarlem, Y.; van Hulse, C.; Veretennikov, D.; Vikhrov, V.; Vilardi, I.; Wang, S.; Yaschenko, S.; Ye, Z.; Yen, S.; Zagrebelnyy, V.; Zeiler, D.; Zihlmann, B.; Zupranski, P.

2011-10-01

403

X-rays and gamma-rays at cosmological distances  

Microsoft Academic Search

Recent work on absorption and reprocessing of gamma-rays at cosmological redshifts as well as the current status of this field of research are discussed. The authors consider Compton scattering and pair production by gamma-rays on cosmic baryonic matter, and photon-photon scattering and photon-photon pair production by gamma-rays and Compton scattering of relativistic pairs on the cosmic blackbody background. The region

A. A. Zdziarski; R. Svensson

1990-01-01

404

Gamma ray polarimetry using a position sensitive germanium detector  

Microsoft Academic Search

Imaging gamma-ray detectors make sensitive polarimeters in the Compton energy regime by measuring the scatter direction of gamma rays. The principle is to capitalize on the angular dependence of the Compton scattering cross section to polarized gamma rays and measure the distribution of scatter directions within the detector. This technique is effective in a double-sided germanium detector between roughly 50keV

R. A Kroeger; W. N Johnson; J. D Kurfess; B. F Phlips

1999-01-01

405

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

406

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

407

Comparison of Theoretical Doubly Differential Cross Sections for Atomic Compton Scattering with Experimantal Data  

NASA Astrophysics Data System (ADS)

Doubly differential cross sections (DDCS) for inelastic photon atom scattering that result in the ejection of a single electron are calculated for selected atoms at various incident photon energies using three different theories. One theory utilizes the relativistic second order S-matrix formalism, the other two are the relativistic and nonrelativistic impulse approximation (RIA and NRIA). All three calculations are done within the independent particle approximation (IPA). DDCS for Copper K-shell ionization with incident photon energy E_in=60 keV, obtained from S-matrix theory, were found to be in good agreement with the experimental values of J. Laukkanen et. al. [1] for all final electron energies. Agreement was better than with RIA and NRIA calculations. Good agreement has also been found for K-shell DDCS with the experimental results of Thanomngam et. al. [2] for Ta and Pb at 320 kev and for Ta at 662 keV. However the DDCS reported for Pb at 662 kev were at least an order of magnitude greater than our theoretical results. We note that such results for Pb at 662 keV, appear to be inconsistent with the earlier singly differential cross sections of Wolf et. al. [3]. In comparisons between S-matrix, RIA and NRIA DDCS for several atoms, it was found that NRIA results were in better agreement with S-matrix and experimental than RIA for the low final photon energy side of the Compton peak. 1. J. Laukkanen, K. Hamalainen and S. Manninen, J. Phys. Condensed Matter 8 2153 (1996). 2. P. Thanomngam and P. N. Johnston, Poster presented at ISRP-9 (2003), submitted for publication in Rad. Phys. And Chem. 3. W. Wolf, H. E. Wolf, L. f. S. Coelho, S. deBarrus, and J. Eichler, Phys. Rev. A 40 3543 (1991).

Lajohn, L. A.; Pratt, R. H.

2004-05-01

408

Compton-scattering study of trigonal, monoclinic, and amorphous phases of Se  

NASA Astrophysics Data System (ADS)

The Compton profiles (CP) and autocorrelation functions (AF) for crystalline trigonal Se (t-Se), polycrystalline trigonal Se (pct-Se), polycrystalline monoclinic Se (pcm-Se), and black amorphous Se (ba-Se), have been determined experimentally from inelastic ?-ray scattering. Two different ?-ray spectrometers have been used, namely one using the 412-keV line of 198Au and the other using the 59.5-keV line of 241Am. The momentum resolutions were 0.41 and 0.56 a.u., respectively. The present results for t-Se, pct-Se, and ba-Se differ significantly from earlier results. The data are analyzed using theoretical results obtained from atomic restricted Hartree-Fock models, free-electron (FE) models, one-dimensional potential array studies, and from self-consistent orthogonalized-plane-wave (SCOPW) calculations based on a local density formalism. Good agreement for t-Se and pct-Se has been obtained between both sets of experimental data and the SCOPW results. The FE model, fulfilling the correct translation symmetry and occupation of the higher Brillouin zones, is shown to explain long-range oscillations of the AF qualitatively but is inadequate for describing the short-range bonding effects. No significant difference within the present resolution was detected between the CP and the AF of pct-Se and ba-Se, contrary to earlier findings. Reasons for this are discussed using the above models. A significant difference between pct-Se and pcm-Se has not been obtained with the Am spectrometer.

Krusius, P.; Pattison, P.; Schneider, J. R.; Kramer, B.; Schülke, W.; Bonse, U.; Treusch, J.

1982-05-01

409

Prototype TIGRE Compton ?-ray balloon-borne telescope  

Microsoft Academic Search

A prototype balloon-borne telescope is being constructed for ?-ray observations in the MeV energy range. The Tracking and Imaging Gamma-Ray Experiment (TIGRE) uses multi-layers of thin silicon detectors to track and measure the energy losses of Compton recoil electrons. When combined with the direction and energy of the Compton scattered ?-ray a unique incident direction for each photon event is

D. Bhattacharya; T. J. O’Neill; A. Akyüz; J. Samimi; A. D. Zych

2004-01-01

410

Compton-scattering studies on the helium atom beyond the impulse approximation  

SciTech Connect

A series expansion of the Born propagator allows one to represent successive corrections to the impulse approximation and exhibits their relative dependence in momentum transfer k and the Compton (target-structure) parameter q. The proposed treatment provides a physical interpretation of the observed Compton defects. It is shown here to be in close agreement with high-energy-electron-impact spectroscopy measurements obtained for helium atoms.

Tavard, C.; Dal Cappello, M.C.; Gasser, F.; Dal Cappello, C.; Wellenstein, H.F.

1983-01-01

411

Compton Versterker (Compton Amplifier).  

National Technical Information Service (NTIS)

The broad wave amplifier was developed to amplify signals from Compton detectors, which are part of the security system for the MEA (Medium Energy Accelerator) linear amplifier in Amsterdam. Compton detectors determine the position of the electrons in the...

J. T. van Es J. C. Verkooijen

1989-01-01

412

A 4D Monte Carlo laser-Compton scattering simulation code for the characterization of the future energy-tunable SLEGS  

Microsoft Academic Search

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

W. Luo; W. Xu; Q. Y. Pan; Z. D. An; X. L. Cai; G. T. Fan; G. W. Fan; Y. J. Li; B. J. Xu; Z. Yan; L. F. Yang

2011-01-01

413

Phantom study of fusion image of CT and SPECT with body-contour generated from external Compton scatter sources  

Microsoft Academic Search

Purpose  A phantom study was conducted to evaluate the feasibility of body contour definition with Compton scatter photons from extemal\\u000a sources of technetium-99m pertechnetate (Tc-99m) to create a fusion image of CT and SPECT images.\\u000a \\u000a \\u000a \\u000a Methods  External sources of 1 mCi (37 MBq) Tc-99m were placed on each collimator, and bodycontour SPECT images were obtained with\\u000a an energy window of 100 keV±25%

Kazuyoshi Suga; Naofumi Matsunaga; Yasuhiko Kawakami; Mataichi Furukawa

2000-01-01

414

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

415

Beam spin asymmetries in deeply virtual Compton scattering (DVCS) with CLAS at 4.8 GeV  

Microsoft Academic Search

We report measurements of the beam spin asymmetry in deeply virtual Compton scattering (DVCS) at an electron beam energy of 4.8 GeV using the CLAS detector at the Thomas Jefferson National Accelerator Facility. The DVCS beam spin asymmetry has been measured in a wide range of kinematics, 1.0p-->e'pX. The number of

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

2009-01-01

416

On the inverse Compton scattering interpretation of the hard X-ray excesses in galaxy clusters: the case of Ophiuchus  

NASA Astrophysics Data System (ADS)

Context: Populations of high energy electrons can produce hard X-ray (HXR) emission in galaxy clusters by up-scattering CMB photons via the inverse Compton scattering (ICS) mechanism. However, this scenario has various astrophysical consequences. Aims: We discuss here the consequences of the presence of a population of high energy particles for the multi-frequency emissivity of the same clusters and the structure of their atmospheres. Methods: We derive predictions for the ICS HXR emission in the specific case of the Ophiuchus cluster (for which an interesting combination of observational limits and theoretical scenarios have been presented) for three main scenarios producing high-E electrons: primary cosmic ray model, secondary cosmic rays model and neutralino DM annihilation scenario. We further discuss the predictions of the Warming Ray model for the cluster atmosphere. Under the assumption to fit the HXR emission observed in Ophiuchus, we explore the consequences that these electron populations induce on the cluster atmosphere. Results: We find that: i) primary electrons can be marginally consistent with the available data provided that the electron spectrum is cutoff at E ? 30 and E ? 90 MeV for electron spectral index values of 3.5 and 4.4, respectively; ii) secondary electron models from pp collisions are strongly inconsistent with the viable gamma-ray limits, cosmic ray protons produce too much heating of the intracluster (IC) gas and their pressure at the cluster center largely exceeds the thermal one; iii) secondary electron models from DM annihilation are also strongly inconsistent with the viable gamma-ray and radio limits, and electrons produce too much heating of the IC gas at the cluster center, unless the neutralino annihilation cross-section is much lower than the proposed value. In that case, however, these models no longer reproduce the HXR excess in Ophiuchus. Conclusions: We conclude that ICS by secondary electrons from both neutralino DM annihilation and pp collisions cannot be the mechanism responsible for the HXR excess emission; primary electrons are still a marginally viable solution provided that their spectrum has a low-energy cutoff at E ? 30-90 MeV. We also find that diffuse radio emission localized at the cluster center is expected in all these models and requires quite low values of the average magnetic field (B ~ 0.1-0.2 ?G in primary and secondary-pp models; B ~ 0.055-0.39 ?G in secondary-DM models) to agree with the available observations. Finally, the WR model (with B ~ 0.4-2.0 ?G) offers, so far, the most accurate description of the cluster in terms of the temperature distribution, heating and pressure and multi-frequency spectral energy distribution. Fermi observations of Ophiuchus will provide further constraints to this model.

Colafrancesco, S.; Marchegiani, P.

2009-08-01

417

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

418

Prompt GeV emission in the synchrotron self-Compton model for gamma-ray bursts  

SciTech Connect

The detection in 10 bursts of an optical counterpart emission (i.e. during the prompt GRB phase) that is 10-10000 brighter than the extrapolation of the burst spectrum to optical frequencies suggests a synchrotron self-Compton origin for the GRB emission, synchrotron producing the optical counterpart emission. In this model, the second upscattering of the burst photons yields a prompt GeV-TeV emission, whose brightness depends strongly on an unknown quantity, the peak energy of the primary synchrotron spectrum. Measurements of the optical, gamma-ray, and GeV prompt fluxes can be used to test the synchrotron self-Compton model for GRBs and to determine directly the total radiative output of GRBs. For a set of 29 GRBs with optical counterpart detections, we find that the expected GeV photon flux should correlate with the fluence of the sub-MeV emission and should anticorrelate with the brightness of the optical counterpart, the strength of these correlations decreasing for an increasing width of the synchrotron peak energy distribution. The detection of a GeV prompt emission consistent with the extrapolation of the burst spectrum to higher energies would rule out the synchrotron self-Compton model if the sub-MeV burst emission were very bright and the (intrinsic) optical counterpart were very dim.

Panaitescu, Alin [Los Alamos National Laboratory

2008-01-01

419

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

NASA Astrophysics Data System (ADS)

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.

1993-02-01

420

Determination of Circular Polarization of gamma-quanta with Energy > 10 MeV using Compton Polarimeter  

Microsoft Academic Search

The circularly polarized gamma-quanta with energy > 10 MeV are formed during\\u000aCompton backscattering of circularly polarized laser photons on an electron\\u000abeam with energy 1.26 GeV. The contribution of nonlinear processes for planned\\u000aparameters of a laser flash[T. Okugi, Y. Kurihara and M. Chiba, Jpn. J. Appl.\\u000aPhys. 35, p. 3677 (1996).] can be rather significant, that leads to

A. S. Arychev; A. P. Potylitsyn; M. N. Strikhanov

2001-01-01

421

A mini transmission gamma-ray Compton polarimeter and measurements of the sign of magnetic moments of radioactive nuclei  

Microsoft Academic Search

A mini transmission gamma-ray Compton polarimeter was developed for the measurement of the sign of magnetic moments of radioactive nuclei with low-temperature nuclear orientation. The signs of the magnetic moments of the following isotopes were determined:193Os [ mu=+0.7297(16) mu N];191 m Ir [ mu=+6.20(9) mu N];192Ir [ mu=+1.924(10) mu N];194Ir [ mu=+0.39(1) mu N];195 m Pt [ mu=-0.605(15) mu N].

E. Scheidemann; R. Eder; E. Hagn; E. Zech

1991-01-01

422

Event Reconstruction and Background Suppression in the LXeGRIT Balloon-Borne Compton Telescope  

Microsoft Academic Search

The application of a 3-D imaging detector, such as a liquid xenon time projection chamber (LXeTPC), as a Compton telescope for MeV gamma-rays relies on the precise measurement of the energy deposits and interaction locations on an eveny-by-event basis. In order to use this information to infer the original gamma-ray direction, the correct sequence of the multiple Compton scatterings has

Elena Aprile; Alessandro Curioni; Karl-Ludwig Giboni; Masanori Kobayashi; Uwe G. Oberlack

2002-01-01

423

Single-photon ionization of helium from 4.5 to 12 keV by Compton scattering and the photoelectric effect  

NASA Astrophysics Data System (ADS)

We have measured the ratio of the cross sections for double-to-single ionization in helium for several monoenergetic photon energies between 4.5 and 12 keV using time-of-flight ion charge state spectroscopy. In this energy range, both the photoelectric effect and inelastic (Compton) scattering contribute significantly to the total cross section. The ionization states caused by Compton scattering were distinguished from those caused by the photoelectric effect by the different recoil energies of the helium ion associated with the two processes. The ratios of the double-to-single ionization cross sections of helium for the photoelectric effect (Rp) and for Compton scattering (Rc) are given, and compared with previous measurements and theoretical calculations. The measured value for Rc at 12 keV is (1.21+/-0.27)%, which agrees well with the theoretical calculations of Andersson and Burgdörfer [Phys. Rev. A 50, R2810 (1994)].

Morgan, D. V.; Bartlett, R. J.

1999-05-01

424

SCATTERING OF GAMMA-RAYS. I. SCATTERED GAMMA-RAYS IN THE LABYRINTH OF SHIELDED Co⁶° IRRADIATION FACILITIES. II. RADIOGRAPHY USING THE SCATTERED $gamma$-RAYS  

Microsoft Academic Search

The intensities and energy spectra of scattered gamma rays in the ; labyrinth of a 3000-C Co⁶° irradiation facilities were measured by means of ; chamber-type detectors and a scintillation spectrometer. Problems concerning the ; radiation differences between the 2 labyrinth sections, the contribution of the ; scattered-rays to the special dosage rate, and the estimation of the dosage rate

Kaminishi

1961-01-01

425

Electronic structure of Ni2TiAl: Theoretical aspects and Compton scattering measurement  

NASA Astrophysics Data System (ADS)

In this paper, we report electron momentum density of Ni2TiAl alloy using an in-house 20 Ci 137Cs (661.65 keV) Compton spectrometer. The experimental data have been analyzed in terms of energy bands and density of states computed using linear combination of atomic orbitals (LCAO) method. In the LCAO computations, we have considered local density approximation, generalized gradient approximation and recently developed second order generalized gradient approximation within the frame work of density functional theory. Anisotropies in theoretical Compton profiles along [1 0 0], [1 1 0] and [1 1 1] directions are also explained in terms of energy bands.

Sahariya, Jagrati; Ahuja, B. L.

2012-11-01

426

Observations of diffuse cosmic gamma radiation between 1.5 and 10 MeV with a balloon-borne double Compton telescope  

Microsoft Academic Search

Results on the diffuse gamma ray flux between 1.5 and 10 Mev from a balloon-borne double Compton telescope are presented. The cosmic gamma ray flux is determined from the flattening of the growth curve near the top of the atmosphere. Corrections have to be made for inelastic neutron-carbon interactions in the scintillator which cause part of the flattening. The gamma

V. Schoenfelder; G. Lichti

1974-01-01

427