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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 (˜10 14 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

Energy distribution of Compton-scattered gamma rays  

E-print Network

DATA AND THEIR ANALYSIS ~ ~ 1 13 Carbon 15 Aluminum 16 Brass 16 VI. Lead DISCUSSION REFERENCES APPENDIX 17 19 23 24 LIST OP ThBLES Table Page Theoretical Doppler broadening of the Compton line Experimental results for each scatterer... background count 53 14 15 16 17 18 19 Experimental Compton spectrum CH2 scatterer Experimental Compton line for CH2 scatterer Experimental Compton spectrum Al scatterer Experimental Compton line for Al scatterer Experimental Compton spectrum brass...

Moreland, Richard Wayne

2012-06-07

3

Resonant Compton scattering and gamma-ray burst continuum spectra  

NASA Technical Reports Server (NTRS)

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

Baring, M. G.

1995-01-01

4

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

5

Design Study for Direction Variable Compton Scattering Gamma Ray  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

6

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

7

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

SciTech Connect

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

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

2010-08-04

8

Laser Compton Scattering Gamma-Ray Beam Source at NewSUBARU Storage Ring  

NASA Astrophysics Data System (ADS)

Laser Compton scattering gamma-ray beam source has been developed at the NewSUBARU synchrotron light facility. The available maximum Gamma-ray photon energy is 76 MeV. The flux of quasi-monochromatic gamma-ray photons (for example: 16.7 MeV, ?E/E ~ 5%) is more than 106photons/sec using a 35 W Nd:YVO4 laser combined with the 1 GeV storage electron beam with an intensity of 300 mA. We used the electron beams at Ee = 0.55 ~ 1.47 GeV for changing the energy of quasi-monochromatic gamma-ray beam. Gamma-ray beams were used for application experiments, a nuclear physics research, a nondestructive inspection of thick material, a generation of positron by pair creation, a magnetic Compton scattering measurements, and a nuclear transmutation.

Miyamoto, S.; Amano, S.; Hashimoto, S.; Sakai, N.; Koizumi, A.; Hashimoto, T.; Shizuma, T.; Utsunomiya, H.; Yamagata, T.; Akimune, H.; Shima, T.; Li, D.; Asano, Y.; Ohkuma, H.

2015-10-01

9

Polarized Compton Scattering and Nucleon Spin Polarizabilities at the Upgraded HI{gamma}S Facility  

SciTech Connect

The HI{gamma}S facility is capable of providing intense beams of linearly and circularly polarized gamma rays, at energies from 2 MeV and soon to extend up to 100 MeV. This paper describes a Compton scattering program which has been designed to measure the electric and magnetic polarizabilities of the proton and the neutron, as well as the spin-polarizabilities of both. Linearly polarized beams will be used to measure the electric and magnetic polarizabilities of the proton, while Compton scattering from the deuteron will lead to values of these fundamental quantities for the neutron. Circularly polarized beams and polarized proton and {sup 3}He targets will be used to extract the four spin-polarizabilities of the nucleons with accuracies ranging from 5-to-25%. These values will be compared to the predictions of Chiral Perturbation Theory and anticipated results from Lattice QCD calculations.

Weller, H. R.; Ahmed, M. W.; Henshaw, S.; Stave, S. [Duke University and Triangle Universities Nuclear Laboratory (TUNL), Box 90308, Durham, North Carolina 27708-0308 (United States)

2009-12-17

10

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

NASA Astrophysics Data System (ADS)

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

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

2009-11-01

11

Design and Operation of a tunable MeV-level Compton-scattering-based (gamma-ray) source  

SciTech Connect

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

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

2009-07-07

12

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

13

The Compton Gamma Ray Observatory  

Microsoft Academic Search

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,

N. Gehrels; E. Chipman; D. Kniffen

1994-01-01

14

Compton scattering revisited  

NASA Astrophysics Data System (ADS)

We review the standard theory of Compton scattering from bound electrons, and we describe recent findings that require modification of the usual understanding, noting the nature of consequences for experiment. The subject began with Compton and scattering from free electrons. Experiment actually involved bound electrons, and this was accommodated with the use of impulse approximation (IA), which described inelastic scattering from bound electrons in terms of scattering from free electrons. This was good for the Compton peak but failed for soft final photons. The standard theory was formalized by Eisenberger and Platzman (EP) [1970. Phys. Rev. A 2, 415], whose work also suggested why impulse approximation was better than one would expect, for doubly differential cross sections (DDCS), but not for triply differential cross sections (TDCS). A relativistic version of IA (RIA) was worked out by Ribberfors [1975. Phys. Rev. B 12, 2067]. And Suri? et al. [1991. Phys. Rev. Lett. 67, 189] and Bergstrom et al. [1993. Phys. Rev. A 48, 1134] developed a full relativistic second order S-matrix treatment, not making impulse approximation, but within independent particle approximation (IPA). Newer developments in the theory of Compton scattering include: (1) Demonstration that the EP estimates of the validity of IA are incorrect, although the qualitative conclusion remains unchanged; IA is not to be understood as the first term in a standard series expansion. (2) The greater validity of IA for DDCS than for the TDCS, which when integrated give DDCS, is related to the existence of a sum rule, only valid for DDCS. (3) The so-called "asymmetry" of a Compton profile is primarily to be understood as simply the shift of the peak position in the profile; symmetric and anti-symmetric deviations from a shifted Compton profile are very small, except for high Z inner shells where further p?·A? effects come into play. (4) Most relativistic effects, except at low energies, are to be understood in terms of simple kinematic modifications of nonrelativistic IA, plus using a relativistic charge density for high Z inner shell states; these shift the peak and change its height. However, for high Z, corrections to RIA persist in the peak region, even at extreme relativistic energies (correction of about 15% for Z=92).

Pratt, R. H.; LaJohn, L. A.; Florescu, V.; Suri?, T.; Chatterjee, B. K.; Roy, S. C.

2010-02-01

15

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

16

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

E-print Network

The Liquid Xenon Gamma-Ray Imaging Telescope (LXeGRIT) is a balloon born experiment sensitive to \\g -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 \\g -ray interactions are accurately measured in one homogeneous volume. To determine the \\g -ray initial direction (Compton imaging), as well as to reject background, the correct sequence of interactions has to be determined. Here we report the development and optimization of an algorithm to reconstruct the Compton scattering sequence and show its performance on Monte Carlo events and LXeGRIT data.

Oberlack, U G; Curioni, A; Egorov, V; Giboni, K L

2000-01-01

17

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

18

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

SciTech Connect

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

Tuschareon, S., E-mail: tuscharoen@hotmail.com; Limkitjaroenporn, P., E-mail: tuscharoen@hotmail.com; Kaewkhao, J., E-mail: tuscharoen@hotmail.com [Center of Excellence in Glass Technology and Materials Science (CEGM), Nakhon Pathom Rajabhat University, Nakhon Pathom, 73000, Thailand and Science Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom, 73000 (Thailand)

2014-03-24

19

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

20

Electron Linac design to drive bright Compton back-scattering gamma-ray sources  

SciTech Connect

The technological development in the field of high brightness linear accelerators and high energy/high quality lasers enables today designing high brilliance Compton-X and Gamma-photon beams suitable for a wide range of applications in the innovative field of nuclear photonics. The challenging requirements of this kind of source comprise: tunable energy (1-20 MeV), very narrow bandwidth (0.3%), and high spectral density (10{sup 4} photons/s/eV). We present here a study focused on the design and the optimization of an electron Linac aimed to meet the source specifications of the European Extreme Light Infrastructure-Nuclear Physics project, currently funded and seeking for an innovative machine design in order to outperform state-of-the-art facilities. We show that the phase space density of the electron beam, at the collision point against the laser pulse, is the main quality factor characterizing the Linac.

Bacci, A.; Rossi, A. R.; Serafini, L. [INFN-MI, Milano (Italy)] [INFN-MI, Milano (Italy); Alesini, D.; Bellaveglia, M.; Boni, R.; Chiadroni, E.; Di Pirro, G.; Esposito, A.; Ferrario, M.; Gallo, A.; Gatti, G.; Ghigo, A.; Spataro, B.; Vaccarezza, C. [INFN-LNF, Frascati, Roma (Italy)] [INFN-LNF, Frascati, Roma (Italy); Antici, P.; Migliorati, M.; Mostacci, A.; Palumbo, L. [University La Sapienza, Roma (Italy)] [University La Sapienza, Roma (Italy); Cianchi, A. [University of Tor Vergata, Roma (Italy)] [University of Tor Vergata, Roma (Italy); and others

2013-05-21

21

The Compton Gamma Ray Observatory  

Microsoft Academic Search

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

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

1993-01-01

22

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

23

Measuring energy dependent polarization in soft gamma-rays using Compton scattering in PoGOLite  

E-print Network

Linear polarization in X- and gamma-rays is an important diagnostic of many astrophysical sources, foremost giving information about their geometry, magnetic fields, and radiation mechanisms. However, very few X-ray polarization measurements have been made, and then only mono-energetic detections, whilst several objects are assumed to have energy dependent polarization signatures. In this paper we investigate whether detection of energy dependent polarization from cosmic sources is possible using the Compton technique, in particular with the proposed PoGOLite balloon-experiment, in the 25-100 keV range. We use Geant4 simulations of a PoGOLite model and input photon spectra based on Cygnus X-1 and accreting magnetic pulsars (100 mCrab). Effective observing times of 6 and 35 hours were simulated, corresponding to a standard and a long duration flight respectively. Both smooth and sharp energy variations of the polarization are investigated and compared to constant polarization signals using chi-square statistics. We can reject constant polarization, with energy, for the Cygnus X-1 spectrum (in the hard state), if the reflected component is assumed to be completely polarized, whereas the distinction cannot be made for weaker polarization. For the accreting pulsar, constant polarization can be rejected in the case of polarization in a narrow energy band with at least 50% polarization, and similarly for a negative step distribution from 30% to 0% polarization.

M. Axelsson; O. Engdegård; F. Ryde; S. Larsson; M. Pearce; L. Hjalmarsdotter; M. Kiss; C. Marini Bettolo; M. Arimoto; C-I. Björnsson; P. Carlson; Y. Fukazawa; T. Kamae; Y. Kanai; J. Kataoka; N. Kawai; W. Klamra; G. Madejski; T. Mizuno; J. Ng; H. Tajima; T. Takahashi; T. Tanaka; M. Ueno; G. Varner; K. Yamamoto

2007-06-28

24

Compton Scattering Sources and Applications at LLNL  

SciTech Connect

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

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

2010-11-04

25

Compton scattering revisited  

NASA Astrophysics Data System (ADS)

Compton scattering of a photon by bound electrons is one of the fundamental processes of interaction of radiation with matter [1].Theoretical treatments of the process are often based on using impulse approximation (IA) which is, at nonrelativistic energies, obtained within A^2 approximation of the electron-photon interaction (the p.A term is neglected). The validity of IA increases and the corrections decrease as the ratio pav/k of average momentum pav of bound electron and the photon momentum transfer k becomes small. The IA is often viewed as the leading term in the pav/k expansion of the exact result. We examine the criteria of validity of IA for the triply differential cross section (TDCS) and for the doubly differential cross section (DDCS), which are different. We find that IA is in fair agreement with the exact expression for DDCS even when the expansion in pav/k is not well convergent. We also examine the importance of the inclusion of the p.A term in IA, needed at relativistic energies even in the peak region. [1] P. Eisenberger and P. M. Platzmann, Phys Rev. A 2, 415 (1970); R. Ribberfors, Phys. Rev. B 12, 2067 (1975); P. M. Bergstrom et al, Phys. Rev. A 48, 1134 (1993); R. H. Pratt et al, Nucl. Instr. and Meth. B 261, 175 (2007).

Suri?, T.; Florescu, V.; Chatterjee, B. K.; Roy, S. C.; Lajohn, L. A.; Pratt, R. H.

2008-05-01

26

The Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

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.

1994-01-01

27

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

28

Compton Gamma-Ray Observatory  

SciTech Connect

The symposium represents the topics on varied aspects ofgamma-ray astronomy. The Compton Gamma-Ray Observatory representsa dramatic increase in capability over previous gamma-ray missions.A large number of reports were presented on the topic of gamma-raybursts. A total of two hundred and ten papers were presented at thesymposium, out of which twenty four have been abstracted for thedatabase. (AIP)

Friedlander, M. (ed.) (Washington University, St. Louis,Missouri (United States)); Gehrels, N.; Macomb, D.J. (eds.) (Laboratory forHigh Energy Astrophysics, NASA/Goddard Space Flight Center,Greenbelt, Maryland (United States))

1993-01-01

29

Timelike Compton Scattering at Jlab  

SciTech Connect

It is demonstrated, that with exclusive final state, data from electron scattering experiments that are recorded with loose trigger requirements can be used to analyze photoproduction reactions. A preliminary results on Timelike Compton Scattering using the electroproduction data from the CLAS detector at Jefferson Lab are presented. In particular, using final state (pe{sup -}e{sup +}) photoproduction of vector mesons and timelike photon is studied. Angular asymmetries in Timelike Compton Scattering region is compared with model predictions in the framework of Generalized Parton Distribution.

Paremuzyan, Rafayel G. [Institut de Physique Nucleaire, Orsay (France)

2014-01-01

30

Compton Gamma Ray Observatory/BATSE observations of energetic electrons scattered by cyclotron resonance with waves from powerful VLF transmitters  

NASA Technical Reports Server (NTRS)

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 we 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, Dayton W.; Imhof, William L.

1994-01-01

31

The Compton Gamma Ray Observatory: mission status  

Microsoft Academic Search

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

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

1994-01-01

32

Compton Gamma-Ray Observatory  

NASA Technical Reports Server (NTRS)

This photograph shows the Compton Gamma-Ray Observatory being released from the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-35 mission in April 1991. The GRO reentered the Earth's atmosphere and ended its successful mission in June 2000. For nearly 9 years, GRO's Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center, kept an unblinking watch on the universe to alert scientist to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of star, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in BATSE's science program.

1991-01-01

33

Compton Gamma-Ray Observatory  

NASA Technical Reports Server (NTRS)

This photograph shows the Compton Gamma-Ray Observatory (GRO) being deployed by the Remote Manipulator System (RMS) arm aboard the Space Shuttle Atlantis during the STS-37 mission in April 1991. The GRO reentered Earth atmosphere and ended its successful mission in June 2000. For nearly 9 years, the GRO Burst and Transient Source Experiment (BATSE), designed and built by the Marshall Space Flight Center (MSFC), kept an unblinking watch on the universe to alert scientists to the invisible, mysterious gamma-ray bursts that had puzzled them for decades. By studying gamma-rays from objects like black holes, pulsars, quasars, neutron stars, and other exotic objects, scientists could discover clues to the birth, evolution, and death of stars, galaxies, and the universe. The gamma-ray instrument was one of four major science instruments aboard the Compton. It consisted of eight detectors, or modules, located at each corner of the rectangular satellite to simultaneously scan the entire universe for bursts of gamma-rays ranging in duration from fractions of a second to minutes. In January 1999, the instrument, via the Internet, cued a computer-controlled telescope at Las Alamos National Laboratory in Los Alamos, New Mexico, within 20 seconds of registering a burst. With this capability, the gamma-ray experiment came to serve as a gamma-ray burst alert for the Hubble Space Telescope, the Chandra X-Ray Observatory, and major gound-based observatories around the world. Thirty-seven universities, observatories, and NASA centers in 19 states, and 11 more institutions in Europe and Russia, participated in the BATSE science program.

1991-01-01

34

The Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

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

35

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

36

Deeply Virtual Compton Scattering off the neutron  

E-print Network

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$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=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.

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; Gómez, 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; Laveissière, G; Le Rose, 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; Real, J S; Reitz, B; Roblin, Y; Roche, J; Sabatie, 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

2007-01-01

37

Deeply Virtual Compton Scattering off the neutron  

SciTech Connect

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$({\\vec e},e'\\gamma)X$ cross section measured at $Q^2$=1.9 GeV$^2$ and $x_B$=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.

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

2007-12-01

38

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

39

Compton scattering in terrestrial gamma-ray flashes detected with the Fermi gamma-ray burst monitor  

NASA Astrophysics Data System (ADS)

Terrestrial gamma-ray flashes (TGFs) are short intense flashes of gamma rays associated with lightning activity in thunderstorms. Using Monte Carlo simulations of the relativistic runaway electron avalanche (RREA) process, theoretical predictions for the temporal and spectral evolution of TGFs are compared to observations made with the Gamma-ray Burst Monitor (GBM) on board the Fermi Gamma-ray Space Telescope. Assuming a single source altitude of 15 km, a comparison of simulations to data is performed for a range of empirically chosen source electron variation time scales. The data exhibit a clear softening with increased source distance, in qualitative agreement with theoretical predictions. The simulated spectra follow this trend in the data, but tend to underestimate the observed hardness. Such a discrepancy may imply that the basic RREA model is not sufficient. Alternatively, a TGF beam that is tilted with respect to the zenith could produce an evolution with source distance that is compatible with the data. Based on these results, we propose that the source electron distributions of TGFs observed by GBM vary on time scales of at least tens of microseconds, with an upper limit of ˜100 ?s.

Fitzpatrick, Gerard; Cramer, Eric; McBreen, Sheila; Briggs, Michael S.; Foley, Suzanne; Tierney, David; Chaplin, Vandiver L.; Connaughton, Valerie; Stanbro, Matthew; Xiong, Shaolin; Dwyer, Joseph; Fishman, Gerald J.; Roberts, Oliver J.; von Kienlin, Andreas

2014-08-01

40

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

41

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

42

COMPTON SCATTERING EMISSION IMAGING BASED ON THE V-LINE RADON TRANSFORM  

E-print Network

COMPTON SCATTERING EMISSION IMAGING BASED ON THE V-LINE RADON TRANSFORM AND ITS SIMULATION R. R, France regnierremi@yahoo.fr(R´emi R´egnier) Abstract The Radon transform (RT) on straight lines deals-dimensional emission imaging from Compton scattered gamma-rays. Its modeling leads to a Radon transform defined

Paris-Sud XI, Université de

43

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.

44

Compton Scattering Studies of Spin and Charge Momentum Densities.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Requires signed TDF. The ground state electron density distribution can be determined from the Doppler broadening of Compton scattered radiation. It is shown that Compton scattering of unpolarised photons leads to a measurement of the total electron momentum density distribution whereas if circularly polarised photons are used, the electron spin dependent density distribution is isolated. The experimental work reported here illustrates both techniques. Directional Compton profile measurements of an iron nickel alloy, gallium arsenide and lead have been performed with 60keV and 412keV unpolarised gamma-radiation and demonstrate the sensitivity of the Compton profile and related functions to changes in the valence electron density resulting from disorder (FeNi), bonding (GaAs) and relativistic effects (Pb). Revision of the data processing procedure has yielded an improvement in the profile symmetry of these results. A new spectrometer dedicated to magnetic Compton studies has been designed and constructed. It uses circularly polarised radiation obtained by viewing the tangent point of the Daresbury synchrotron wiggler line at a small inclination to the orbital plane. Magnetic Compton profile measurements of polycrystalline iron undertaken with 54keV circularly polarised synchrotron radiation (CPSR) show a larger central dip than predicted by band theory calculations of the electron spin dependent density distribution. Data on polycrystalline cobalt has also been obtained. A transmission scattering geometry and 60keV CPSR have been used to measure, for the first time, directional Compton profiles of the unpaired spin electrons in a single crystal of iron. Separation of the contributions from the majority and minority spin electrons provide a more critical test of band theory than is possible with polycrystalline results.

Timms, David N.

45

Compton scatter transition radiation detectors for ACCESS  

NASA Astrophysics Data System (ADS)

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

Case, Gary L.; Cherry, Michael L.

2004-01-01

46

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

47

Exclusive Compton Scattering on the Proton  

Microsoft Academic Search

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

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

1999-01-01

48

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

49

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

50

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

51

Nonlinear X-ray Compton Scattering  

E-print Network

X-ray scattering is a weak linear probe of matter. It is primarily sensitive to the position of electrons and their momentum distribution. Elastic X-ray scattering forms the basis of atomic structural determination while inelastic Compton scattering is often used as a spectroscopic probe of both single-particle excitations and collective modes. X-ray free-electron lasers (XFELs) are unique tools for studying matter on its natural time and length scales due to their bright and coherent ultrashort pulses. However, in the focus of an XFEL the assumption of a weak linear probe breaks down, and nonlinear light-matter interactions can become ubiquitous. The field can be sufficiently high that even non-resonant multiphoton interactions at hard X-rays wavelengths become relevant. Here we report the observation of one of the most fundamental nonlinear X-ray-matter interactions, the simultaneous Compton scattering of two identical photons producing a single photon at nearly twice the photon energy. We measure scattered...

Fuchs, Matthias; Chen, Jian; Ghimire, Shambhu; Shwartz, Sharon; Kozina, Michael; Jiang, Mason; Henighan, Thomas; Bray, Crystal; Ndabashimiye, Georges; Bucksbaum, P H; Feng, Yiping; Herrmann, Sven; Carini, Gabriella; Pines, Jack; Hart, Philip; Kenney, Christopher; Guillet, Serge; Boutet, Sebastien; Williams, Garth; Messerschmidt, Marc; Seibert, Marvin; Moeller, Stefan; Hastings, Jerome B; Reis, David A

2015-01-01

52

The Mathematical Foundations of 3D Compton Scatter Emission Imaging  

PubMed Central

The mathematical principles of tomographic imaging using detected (unscattered) X- or gamma-rays are based on the two-dimensional Radon transform and many of its variants. In this paper, we show that two new generalizations, called conical Radon transforms, are related to three-dimensional imaging processes based on detected Compton scattered radiation. The first class of conical Radon transform has been introduced recently to support imaging principles of collimated detector systems. The second class is new and is closely related to the Compton camera imaging principles and invertible under special conditions. As they are poised to play a major role in future designs of biomedical imaging systems, we present an account of their most important properties which may be relevant for active researchers in the field. PMID:18382608

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

2007-01-01

53

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

Microsoft Academic Search

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\\u000a 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\\u000a is brought

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

2010-01-01

54

Compton scattering measurements from dense plasmas  

SciTech Connect

Compton scattering has been developed for accurate measurements of densities and temperatures in dense plasmas. One future challenge is the application of this technique to characterize compressed matter on the National Ignition Facility where hydrogen and beryllium will approach extremely dense states of matter of up to 1000 g/cc. In this regime, the density, compressibility, and capsule fuel adiabat may be directly measured from the Compton scattered spectrum of a high-energy x-ray line source. Specifically, the scattered spectra directly reflect the electron velocity distribution. In non-degenerate plasmas, the width provides an accurate measure of the electron temperatures, while in partially Fermi degenerate systems that occur in laser-compressed matter it provides the Fermi energy and hence the electron density. Both of these regimes have been accessed in experiments at the Omega laser by employing isochorically heated solid-density beryllium and moderately compressed beryllium foil targets. In the latter experiment, compressions by a factor of 3 at pressures of 40 Mbar have been measured in excellent agreement with radiation hydrodynamic modeling.

Glenzer, S H; Neumayer, P; Doeppner, T; Landen, L; Lee, R W; Wallace, R; Weber, S; Lee, H J; Kritcher, A L; Falcone, R; Regan, S P; Sawada, H; Meyerhofer, D D; Gregori, G; Fortmann, C; Schwarz, V; Redmer, R

2007-10-02

55

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

56

Modeling and simulation results on a new Compton scattering tomography modality  

E-print Network

that the Compton effect (Fig. 1) is the scattering of X- or gamma-photons with electric charges. The energy (X-ray scanner, Single Photon Emission Computed Tomography, Positron Emission Tomography, etc been advocated. The camera records now images labeled by scattered photon energy or equivalently

Nguyen-Verger, Maï K.

57

Timelike Virtual Compton Scattering from Electron-Positron Radiative Annihilation  

SciTech Connect

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

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

2009-03-31

58

Timelike Virtual Compton Scattering from Electron-Positron Radiative Annihilation  

SciTech Connect

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

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

2009-01-01

59

Comptonization of gamma rays by cold electrons  

NASA Technical Reports Server (NTRS)

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

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

1991-01-01

60

A novel Compton camera design featuring a rear-panel shield for substantial noise reduction in gamma-ray images  

NASA Astrophysics Data System (ADS)

After the Japanese nuclear disaster in 2011, large amounts of radioactive isotopes were released and still remain a serious problem in Japan. Consequently, various gamma cameras are being developed to help identify radiation hotspots and ensure effective decontamination operation. The Compton camera utilizes the kinematics of Compton scattering to contract images without using a mechanical collimator, and features a wide field of view. For instance, we have developed a novel Compton camera that features a small size (13 × 14 × 15 cm3) and light weight (1.9 kg), but which also achieves high sensitivity thanks to Ce:GAGG scintillators optically coupled wiith MPPC arrays. By definition, in such a Compton camera, gamma rays are expected to scatter in the ``scatterer'' and then be fully absorbed in the ``absorber'' (in what is called a forward-scattered event). However, high energy gamma rays often interact with the detector in the opposite direction - initially scattered in the absorber and then absorbed in the scatterer - in what is called a ``back-scattered'' event. Any contamination of such back-scattered events is known to substantially degrade the quality of gamma-ray images, but determining the order of gamma-ray interaction based solely on energy deposits in the scatterer and absorber is quite difficult. For this reason, we propose a novel yet simple Compton camera design that includes a rear-panel shield (a few mm thick) consisting of W or Pb located just behind the scatterer. Since the energy of scattered gamma rays in back-scattered events is much lower than that in forward-scattered events, we can effectively discriminate and reduce back-scattered events to improve the signal-to-noise ratio in the images. This paper presents our detailed optimization of the rear-panel shield using Geant4 simulation, and describes a demonstration test using our Compton camera.

Nishiyama, T.; Kataoka, J.; Kishimoto, A.; Fujita, T.; Iwamoto, Y.; Taya, T.; Ohsuka, S.; Nakamura, S.; Hirayanagi, M.; Sakurai, N.; Adachi, S.; Uchiyama, T.

2014-12-01

61

Experimental performance of double-scattering Compton camera with anthropomorphic phantom  

NASA Astrophysics Data System (ADS)

In proton therapy, it is important to very accurately determine the range of the proton beam. Recently it was found that this range can be determined from the distribution of the prompt gammas generated along the beam's passage. The Compton imaging technique can be considered to be a promising candidate for accurate determination of prompt gamma distributions, in that it produces a better image for higher-energy gammas when compared with conventional mechanical-collimation-type imagers. In the present study, the Compton imaging technique was evaluated by experimentally obtaining Compton images of relatively high-energy gamma sources positioned in an anthropomorphic phantom. Preparatory to that, two point-like gamma sources, 137Cs (662 keV) and 22Na (1275 keV), were placed in the brain region of the phantom at different depths and imaged using a double-scattering Compton camera. The Compton camera, recently developed as a prototype system, consists of two position-sensitive semiconductor detectors as scatterer detectors and a scintillation detector as an absorber detector. The evaluated imaging and angular resolutions for the source energies of 662 and 1275 keV were 13.7 mm and 5.9° FWHM and 11.4 mm and 3.8° FWHM, respectively.

Seo, H.; Park, J. H.; Ushakov, A.; Kim, C. H.; Kim, J. K.; Lee, J. H.; Lee, C. S.; Lee, J. S.

2011-01-01

62

An energy-subtraction Compton scatter camera design for in vivo medical imaging of radiopharmaceuticals  

SciTech Connect

A Compton scatter camera (CSC) design is proposed for imaging radioisotopes used as biotracers. A clinical version may increase sensitivity by a factor of over 100, while maintaining or improving spatial resolution, as compared with existing Anger cameras that use lead collimators. This novel approach is based on using energy subtraction ({Delta}E = E{sub 0} {minus} E{sub SC}, where E{sub 0}, {Delta}E, and E{sub SC} are the energy of the emitted gamma ray, the energy deposited by the initial Compton scatter, and the energy of the Compton scattered photon) to determine the amount of energy deposited in the primary system. The energy subtraction approach allows the requirement of high energy resolution to be placed on a secondary detector system instead of the primary detector system. Requiring primary system high energy resolution has significantly limited previous CSC designs for medical imaging applications. Furthermore, this approach is dependent on optimizing the camera design for data acquisition of gamma rays that undergo only one Compton scatter in a low-Z primary detector system followed by a total absorption of the Compton scattered photon in a high-Z secondary detector system. The proposed approach allows for a more compact primary detector system, a more simplified pulse processing interface, and a much less complicated detector cooling scheme as compared with previous CSC designs. Analytical calculations and Monte Carlo simulation results for some specific detector materials and geometries are presented.

Rohe, R.C.; Valentine, J.D. [Univ. of Cincinnati, OH (United States)] [Univ. of Cincinnati, OH (United States)

1996-12-01

63

Optimal geometrical configuration of a double-scattering compton camera for maximum imaging resolution and sensitivity  

NASA Astrophysics Data System (ADS)

A novel type of Compton camera, called a double-scattering Compton imager (DOCI), is under development for nuclear medicine and molecular imaging applications. Two plane-type position-sensitive semiconductor detectors are employed as the scatterer detectors, and a 3?×3? cylindrical NaI(Tl) scintillation detector is employed as the absorber detector. This study determined the optimal geometrical configuration of these component detectors to maximize the performance of the Compton camera in imaging resolution and sensitivity. To that end, the Compton camera was simulated very realistically, with the GEANT4 detector simulation toolkit, including various detector characteristics such as energy resolution, spatial resolution, energy discrimination, and Doppler energy broadening. According to our simulation results, the Compton camera is expected to show its maximum performance when the two scatterer detectors are positioned in parallel, with ˜8 cm of separation. The Compton camera will show the maximum performance also when the gamma-ray energy is about 500 keV, which suggests that the Compton camera is a suitable device to image the distribution of the positron emission tomography (PET) isotopes in the human body.

Seo, Hee; Lee, Se Hyung; Kim, Chan Hyeong; An, So Hyun; Lee, Ju Hahn; Lee, Chun Sik

2008-06-01

64

A Future Laser Compton Scattering (LCS) ?-Ray Source: SLEGS at SSRF  

Microsoft Academic Search

The Shanghai Synchrotron Radiation Facility (SSRF) is a third-generation synchrotron radiation light source and will come into commission in April 2009. The project Shanghai Laser Electron Gamma Source (SLEGS), which is a high intensity ?-ray beamline based on Laser Compton Scattering (LCS) between relativistic electron bunches and a laser, has been proposed at the SSRF. According to our simulations, the

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

2009-01-01

65

Inverse Compton Scattering in Quasar Radio Lobes and the Spectrum of Relativistic Electrons  

Microsoft Academic Search

We propose to exploit the high spatial resolution and sensitivity of Chandra to observe 3 powerful steep spectrum radio loud quasars with the aim to study the extended Inverse Compton (IC) emission from the radio lobes. According to theoretical models (Brunetti et al. 1997) IC scattering of the infrared and optical nuclear radiation field from mildly relativistic electrons (gamma about

Gianfranco Brunetti

2000-01-01

66

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

67

Proton Compton scattering in a unified proton-Delta Model  

E-print Network

We develop a field-theoretic model for the description of proton Compton scattering in which the proton and its excited state, the \\Delta+ resonance, are described as part of one multiplet with a single Rarita-Schwinger wavefunction. In order to describe the phenomena observed, it is necessary to incorporate both minimal and non-minimal couplings. The minimal coupling reflects the fact that the \\Delta+ is a charged particle, and in this model the minimal coupling contributes also to the M1 magnetic transition via the \\gamma N\\Delta vertex. The non-minimal couplings consist of five electromagnetic form-factors, which are accessed at fixed and vanishing momentum-transfer squared with real photons in Compton scattering experiments, therefore it is possible to extract a rather well-determined set of optimal parameters which reasonably well fit the data in the resonance region 140-450 MeV. The crucial parameter which determines the \\gamma N\\Delta transition amplitude and therefore the height of the resonance peak is equal to 3.66 +- 0.03, in units of \\mu_N. We find that this parameter also primarily determines the contributions to magnetic polarizability in this model. In the low-energy region up to 140 MeV, we separately fit the electric and magnetic polarizabilities, while keeping the other parameters fixed and obtain values in line with previous approaches. The basic model is then extended by incorporating the sigma-meson channel with the currently favored parameters, and the pion vertex corrections.

Yun Zhang; Konstantin Savvidy

2013-05-16

68

Inverse Compton Scattering in Mildly Relativistic Plasma  

NASA Technical Reports Server (NTRS)

We investigated the effect of inverse Compton scattering in mildly relativistic static and moving plasmas with low optical depth using Monte Carlo simulations, and calculated the Sunyaev-Zel'dovich effect in the cosmic background radiation. Our semi-analytic method is based on a separation of photon diffusion in frequency and real space. We use Monte Carlo simulation to derive the intensity and frequency of the scattered photons for a monochromatic incoming radiation. The outgoing spectrum is determined by integrating over the spectrum of the incoming radiation using the intensity to determine the correct weight. This method makes it possible to study the emerging radiation as a function of frequency and direction. As a first application we have studied the effects of finite optical depth and gas infall on the Sunyaev-Zel'dovich effect (not possible with the extended Kompaneets equation) and discuss the parameter range in which the Boltzmann equation and its expansions can be used. For high temperature clusters (k(sub B)T(sub e) greater than or approximately equal to 15 keV) relativistic corrections based on a fifth order expansion of the extended Kompaneets equation seriously underestimate the Sunyaev-Zel'dovich effect at high frequencies. The contribution from plasma infall is less important for reasonable velocities. We give a convenient analytical expression for the dependence of the cross-over frequency on temperature, optical depth, and gas infall speed. Optical depth effects are often more important than relativistic corrections, and should be taken into account for high-precision work, but are smaller than the typical kinematic effect from cluster radial velocities.

Molnar, S. M.; Birkinshaw, M.

1998-01-01

69

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

70

Coded-aperture Compton camera for gamma-ray imaging  

NASA Astrophysics Data System (ADS)

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

Farber, Aaron M.

71

Monte Carlo study of multiple scatter effects in Compton scatter densitometry  

SciTech Connect

The contribution of multiple scatter to the measured signal in x- and gamma-ray Compton scatter densitometry has been investigated theoretically by the use of Monte Carlo techniques to follow individual photon life histories. A three component phantom was employed in the computer model to simulate the patient at three examination sites; the radius/ulna, the femoral neck, and the lumbar spine. Monoenergetic radiation beams of 60- and 100-keV photons and polyenergetic x-ray spectra of 100 and 140 kVp were used. Scattered events were detected over 360 degrees and classified according to their origin and frequency of scatter. The single scatter in bone to multiple scatter ratio was studied as an indication of the signal-to-noise ratio and this was found to vary with phantom size but was independent of photon energy. Correction factors to be used in a clinical densitometer to account for the inclusion of multiple scatter events were computed. These were found to be 0.65-0.58 at the optimum scattering angles for the phantoms considered.

Speller, R.D.; Horrocks, J.A.

1988-09-01

72

Electron Trajectory Reconstruction for Advanced Compton Imaging of Gamma Rays  

NASA Astrophysics Data System (ADS)

Gamma-ray imaging is useful for detecting, characterizing, and localizing sources in a variety of fields, including nuclear physics, security, nuclear accident response, nuclear medicine, and astronomy. Compton imaging in particular provides sensitivity to weak sources and good angular resolution in a large field of view. However, the photon origin in a single event sequence is normally only limited to the surface of a cone. If the initial direction of the Compton-scattered electron can be measured, the cone can be reduced to a cone segment with width depending on the uncertainty in the direction measurement, providing a corresponding increase in imaging sensitivity. Measurement of the electron's initial direction in an efficient detection material requires very fine position resolution due to the electron's short range and tortuous path. A thick (650 mum), fully-depleted charge-coupled device (CCD) developed for infrared astronomy has 10.5-mum position resolution in two dimensions, enabling the initial trajectory measurement of electrons of energy as low as 100 keV. This is the first time the initial trajectories of electrons of such low energies have been measured in a solid material. In this work, the CCD's efficacy as a gamma-ray detector is demonstrated experimentally, using a reconstruction algorithm to measure the initial electron direction from the CCD track image. In addition, models of fast electron interaction physics, charge transport and readout were used to generate modeled tracks with known initial direction. These modeled tracks allowed the development and refinement of the reconstruction algorithm. The angular sensitivity of the reconstruction algorithm is evaluated extensively with models for tracks below 480 keV, showing a FWHM as low as 20° in the pixel plane, and 30° RMS sensitivity to the magnitude of the out-of-plane angle. The measurement of the trajectories of electrons with energies as low as 100 keV have the potential to make electron track Compton imaging an effective means of reducing image background for photons of energy as low as 500 keV, or even less. The angular sensitivity of the reconstruction algorithm was also evaluated experimentally, by measuring electron tracks in the CCD in coincidence with the scattered photon in a germanium double-sided strip detector. By this method, electron tracks could be measured with the true initial direction known to within 3° FWHM, and the angular response of the algorithm compared to the known direction. The challenge of this experiment lay in the low geometric efficiency for photons scattering into the germanium, the poor time resolution in the current CCD implementation, and the resulting signal-to-background ratio of about 10--4 for photons scattered from the CCD into the germanium detector. Nonetheless, 87 events were measured in the FWHM of the total energy deposited and the angular resolution measure, with electron tracks between 160 keV and 360 keV in energy. The electron tracks from true coincident event sequences showed a FWHM in the pixel plane of 23°, and excellent agreement with the distribution calculated with models, with likelihood p-values of 0.44 and 0.73. Thus, the models used for the more thorough evaluation of angular sensitivities are shown to be consistent with the measured tracks from true coincident event sequences.

Plimley, Brian Christopher

73

Generation of 9 MeV -rays by all-laser-driven Compton scattering with second-harmonic laser light  

E-print Network

Generation of 9 MeV -rays by all-laser-driven Compton scattering with second-harmonic laser light); published July 7, 2014 Gamma-ray photons with energy >9 MeV were produced when second to scatter. Since the two pulses play very different roles in the -ray generation process, and thus have

Umstadter, Donald

74

Narrowband inverse Compton scattering x-ray sources at high laser intensities  

E-print Network

Narrowband x- and gamma-ray sources based on the inverse Compton scattering of laser pulses suffer from a limitation of the allowed laser intensity due to the onset of nonlinear effects that increase their bandwidth. It has been suggested that laser pulses with a suitable frequency modulation could compensate this ponderomotive broadening and reduce the bandwidth of the spectral lines, which would allow to operate narrowband Compton sources in the high-intensity regime. In this paper we, therefore, present the theory of nonlinear Compton scattering in a frequency modulated intense laser pulse. We systematically derive the optimal frequency modulation of the laser pulse from the scattering matrix element of nonlinear Compton scattering, taking into account the electron spin and recoil. We show that, for some particular scattering angle, an optimized frequency modulation completely cancels the ponderomotive broadening for all harmonics of the backscattered light. We also explore how sensitive this compensation depends on the electron beam energy spread and emittance, as well as the laser focusing.

D. Seipt; S. G. Rykovanov; A. Surzhykov; S. Fritzsche

2014-12-08

75

Spin and orbital magnetization loops obtained using magnetic Compton scattering  

SciTech Connect

We present an application of magnetic Compton scattering (MCS) to decompose a total magnetization loop into spin and orbital magnetization contributions. A spin magnetization loop of SmAl{sub 2} was measured by recording the intensity of magnetic Compton scattering as a function of applied magnetic field. Comparing the spin magnetization loop with the total magnetization one measured by a vibrating sample magnetometer, the orbital magnetization loop was obtained. The data display an anti-coupled behavior between the spin and orbital magnetizations and confirm that the orbital part dominates the magnetization.

Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198 (Japan)] [Japan Synchrotron Radiation Research Institute, SPring-8, Hyogo 679-5198 (Japan); Koizumi, A. [Graduate School of Materials Science, University of Hyogo, Hyogo 678-1297 (Japan)] [Graduate School of Materials Science, University of Hyogo, Hyogo 678-1297 (Japan)

2013-02-25

76

Single and double polarization observables in timelike Compton scattering off proton  

E-print Network

We study the exclusive photoproduction of a lepton pair off the proton with the aim of studying the proton quark structure via the Generalized Parton Distributions (GPD) formalism. After deriving the amplitudes of the processes contributing to the $\\gamma P\\to P' e^+e^-$, the Timelike Compton Scattering and the Bethe-Heitler process, we calculate all unpolarized, single- and double- beam-target spin observables in the valence region in terms of GPDs.

Boër, Marie; Vanderhaeghen, Marc

2015-01-01

77

Unified ab initio treatment of attosecond photoionization and Compton scattering  

NASA Astrophysics Data System (ADS)

We present a new theoretical approach to attosecond laser-assisted photo- and Compton ionization. Attosecond x-ray absorption and scattering are described by \\hat{\\mathscr{S}}^{(1,2)} -matrices, which are coherent superpositions of 'monochromatic' \\skew{3}\\hat{S}^{(1,2)} -matrices in a laser-modified Furry representation. Besides refining the existing theory of the soft x-ray photoelectron attosecond streak camera and spectral phase interferometry (ASC and ASPI), we formulate a theory of hard x-ray photoelectron and Compton ASC and ASPI. The resulting scheme has a simple structure and leads to closed-form expressions for ionization amplitudes. We investigate Compton electron interference in the separable Coulomb-Volkov continuum with both Coulomb and laser fields treated non-perturbatively. We find that at laser-field intensities below 1013 Wcm-2 normalized Compton lines almost coincide with the lines obtained in the laser-free regime. At higher intensities, attosecond interferences survive integration over electron momenta, and feature prominently in the Compton lines themselves. We define a regime where the electron ground-state density can be measured with controllable accuracy in an attosecond time interval. The new theory provides a firm basis for extracting photo- and Compton electron phases and atomic and molecular wavefunctions from experimental data.

Yudin, G. L.; Bondar, D. I.; Patchkovskii, S.; Corkum, P. B.; Bandrauk, A. D.

2009-10-01

78

Deeply Virtual Compton Scattering and Exclusive Meson Production  

NASA Astrophysics Data System (ADS)

A selection of hard exclusive measurements (deeply virtual Compton Scattering and meson production) from past, present and future experimental programs are reviewed. The goal is the determination of the Generalized Parton Distributions which offer one of the most complete description of the partonic structure of the nucleon.

d'Hose, Nicole

2015-01-01

79

New JLab/Hall A Deeply Virtual Compton Scattering results  

E-print Network

New data points for unpolarized Deeply Virtual Compton Scattering cross sections have been extracted from the E00-110 experiment at Q$^2$=1.9 GeV$^2$ effectively doubling the statistics available in the valence region. A careful study of systematic uncertainties has been performed.

Maxime Defurne

2015-02-11

80

Parametric interaction and backward wave oscillation in stimulated Compton scattering  

Microsoft Academic Search

Stimulated Compton-Raman scattering and free electron lasers are formulated as parametric (four-photon) or three-wave interaction processes. Manley-Rowe relations and depletable pump equations are derived for both free electron lasers and optical klystron schemes. A process of backward wave oscillation is predicted when a pump radiation field is back scattered off a codirectionally propagating e beam with frequency down conversion. A

A. Gover

1983-01-01

81

Parametric interaction and backward wave oscillation in stimulated Compton scattering  

NASA Astrophysics Data System (ADS)

Stimulated Compton-Raman scattering and free electron lasers are formulated as parametric (four-photon) or three-wave interaction processes. Manley-Rowe relations and depletable pump equations are derived for both free electron lasers and optical klystron schemes. A process of backward wave oscillation is predicted when a pump radiation field is back scattered off a codirectionally propagating e beam with frequency down conversion. A practicable experiment in the optical regime is proposed to demonstrate this effect.

Gover, A.

1983-04-01

82

A low energy bound atomic electron Compton scattering model for Geant4  

NASA Astrophysics Data System (ADS)

A two-body fully relativistic three-dimensional scattering framework has been utilised to develop an alternative Compton scattering computational model to those adapted from Ribberfors' work for Monte Carlo modelling of Compton scattering. Using a theoretical foundation that ensures the conservation of energy and momentum in the relativistic impulse approximation, this new model, the Monash University Compton scattering model, develops energy and directional algorithms for both the scattered photon and ejected Compton electron from first principles. The Monash University Compton scattering model was developed to address the limitation of the Compton electron directionality algorithms of other computational models adapted from Ribberfors' work. Here the development of the Monash University Compton scattering model, including its implementation in a Geant4 low energy electromagnetic physics class, G4LowEPComptonModel, is outlined. Assessment of the performance of G4LowEPComptonModel was undertaken in two steps: (1) comparison with respect to the two standard Compton scattering classes of Geant4 version 9.5, G4LivermoreComptonModel and G4PenelopeComptonModel, and (2) experimental comparison with respect to Compton electron kinetic energy spectra obtained from the Compton scattering of 662 keV photons off the K-shell of gold. Both studies illustrate that the Monash University Compton scattering model, and in turn G4LowEPComptonModel, is a viable replacement for the majority of computational models that have been adapted from Ribberfors' work. It was also shown that the Monash University Compton scattering model is able to reproduce the Compton scattering triply differential cross-section Compton electron kinetic energy spectra of 662 keV photons K-shell scattering off of gold to within experimental uncertainty.

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

2014-11-01

83

Compton scattering of quasi-real virtual photons at LEP  

NASA Astrophysics Data System (ADS)

Compton scattering of quasi-real virtual photons, ?e± ? ?e±, is studied with 0.6 fb-1 of data collected by the L3 detector at the LEP e+e- collider at centre-of-mass energies ?{ s} = 189- 209 GeV. About 4500 events produced by the interaction of virtual photons emitted by e± of one beam with e? of the opposite beam are collected for effective centre-of-mass energies of the photon-electron and photon-positron systems in the range from ?{s?} = 35 GeV up to ?{s?} = 175 GeV, the highest energy at which Compton scattering was ever probed. The cross sections of the ?e± ? ?e± process as a function of ?{s?} and of the rest-frame scattering angle are measured, combined with previous L3 measurements down to ?{s?} ? 20 GeV, and found to agree with the QED expectations.

Achard, P.; Adriani, O.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink, G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger, J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y. H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; de Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F. J.; Extermann, P.; Falagan, M. A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, P. H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Yu.; Ganguli, S. N.; Garcia-Abia, P.; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z. F.; Grenier, G.; Grimm, O.; Gruenewald, M. W.; Guida, M.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Hervé, A.; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S. R.; Jin, B. N.; Jindal, P.; Jones, L. W.; de Jong, P.; Josa-Mutuberría, I.; Kaur, M.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.; Kopal, M.; Koutsenko, V.; Kräber, M.; Kraemer, R. W.; Krüger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J. M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C. H.; Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W. G.; Malgeri, L.; Malinin, A.; Maña, C.; Mans, J.; Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W. J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G. B.; Muanza, G. S.; Muijs, A. J. M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Nowak, H.; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, K.; Roe, B. P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, S.; Rubio, J. A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schopper, H.; Schotanus, D. J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L. Z.; Sushkov, S.; Suter, H.; Swain, J. D.; Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel C. C.; Ting, S. M.; Tonwar, S. C.; Tóth, J.; Tully, C.; Tung, K. L.; Ulbricht, J.; Valente, E.; Van de Walle, R. T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A. A.; Wadhwa, M.; Wang, Q.; Wang, X. L.; Wang, Z. M.; Weber, M.; Wynhoff, S.; Xia, L.; Xu, Z. Z.; Yamamoto, J.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yeh, S. C.; Zalite, An.; Zalite, Yu.; Zhang, Z. P.; Zhao, J.; Zhu, G. Y.; Zhu, R. Y.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.; Zöller, M.

2005-06-01

84

Compton scattering of quasi-real virtual photons at LEP  

NASA Astrophysics Data System (ADS)

Compton scattering of quasi-real virtual photons, ?e??e, is studied with 0.6 fb-1 of data collected by the L3 detector at the LEP ee collider at centre-of-mass energies s=189 209 GeV. About 4500 events produced by the interaction of virtual photons emitted by e of one beam with e of the opposite beam are collected for effective centre-of-mass energies of the photon electron and photon positron systems in the range from s=35 GeV up to s=175 GeV, the highest energy at which Compton scattering was ever probed. The cross sections of the ?e??e process as a function of s and of the rest-frame scattering angle are measured, combined with previous L3 measurements down to s?20 GeV, and found to agree with the QED expectations.

L3 Collaboration; Achard, P.; Adriani, O.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M. G.; Anderhub, H.; Andreev, V. P.; Anselmo, F.; Arefiev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S. V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillère, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B. L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J. J.; Blyth, S. C.; Bobbink, G. J.; Böhm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J. G.; Brochu, F.; Burger, J. D.; Burger, W. J.; Cai, X. D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y. H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G. M.; Chen, H. F.; Chen, H. S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de La Cruz, B.; Cucciarelli, S.; de Asmundis, R.; Déglon, P.; Debreczeni, J.; Degré, A.; Dehmelt, K.; Deiters, K.; Della Volpe, D.; Delmeire, E.; Denes, P.; Denotaristefani, F.; de Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M. T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F. J.; Extermann, P.; Falagan, M. A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J. H.; Filthaut, F.; Fisher, P. H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Yu.; Ganguli, S. N.; Garcia-Abia, P.; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z. F.; Grenier, G.; Grimm, O.; Gruenewald, M. W.; Guida, M.; Gupta, V. K.; Gurtu, A.; Gutay, L. J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Hervé, A.; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S. R.; Jin, B. N.; Jindal, P.; Jones, L. W.; de Jong, P.; Josa-Mutuberría, I.; Kaur, M.; Kienzle-Focacci, M. N.; Kim, J. K.; Kirkby, J.; Kittel, W.; Klimentov, A.; König, A. C.; Kopal, M.; Koutsenko, V.; Kräber, M.; Kraemer, R. W.; Krüger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J. M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C. H.; Lin, W. T.; Linde, F. L.; Lista, L.; Liu, Z. A.; Lohmann, W.; Longo, E.; Lu, Y. S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W. G.; Malgeri, L.; Malinin, A.; Maña, C.; Mans, J.; Martin, J. P.; Marzano, F.; Mazumdar, K.; McNeil, R. R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W. J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G. B.; Muanza, G. S.; Muijs, A. J. M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Novak, T.; Nowak, H.; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, T.; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroué, P. A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Rahal-Callot, G.; Rahaman, M. A.; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P. G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, K.; Roe, B. P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, S.; Rubio, J. A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schäfer, C.; Schegelsky, V.; Schmidt-Kaerst, S.; Schopper, H.; Schotanus, D. J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D. P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L. Z.; Sushkov, S.; Suter, H.; Swain, J. D.; Szillasi, Z.; Tang, X. W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, C.; Ting, Samuel C. C.; Ting, S. M.; Tonwar, S. C.; Tóth, J.; Tully, C.; Tung, K. L.; Ulbricht, J.; Valente, E.; van de Walle, R. T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobiev, I.; Vorobyov, A. A.; Wadhwa, M.; Wang, Q.; Wang, X. L.; Wang, Z. M.; Weber, M.; Wynhoff, S.; Xia, L.; Xu, Z. Z.; Yamamoto, J.; Yang, B. Z.; Yang, C. G.; Yang, H. J.; Yang, M.; Yeh, S. C.; Zalite, An.; Zalite, Yu.; Zhang, Z. P.; Zhao, J.; Zhu, G. Y.; Zhu, R. Y.; Zhuang, H. L.; Zichichi, A.; Zimmermann, B.

2005-06-01

85

Advanced Laser-Compton Gamma-Ray Sources for Nuclear Materials Detection, Assay and Imaging  

NASA Astrophysics Data System (ADS)

Highly-collimated, polarized, mono-energetic beams of tunable gamma-rays may be created via the optimized Compton scattering of pulsed lasers off of ultra-bright, relativistic electron beams. Above 2 MeV, the peak brilliance of such sources can exceed that of the world's largest synchrotrons by more than 15 orders of magnitude and can enable for the first time the efficient pursuit of nuclear science and applications with photon beams, i.e. Nuclear Photonics. Potential applications are numerous and include isotope-specific nuclear materials management, element-specific medical radiography and radiology, non-destructive, isotope-specific, material assay and imaging, precision spectroscopy of nuclear resonances and photon-induced fission. This review covers activities at the Lawrence Livermore National Laboratory related to the design and optimization of mono-energetic, laser-Compton gamma-ray systems and introduces isotope-specific nuclear materials detection and assay applications enabled by them.

Barty, C. P. J.

2015-10-01

86

Expected level of self-Compton scattering in radio loud quasars  

NASA Technical Reports Server (NTRS)

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

Bloom, Steven D.; Marscher, Alan P.

1992-01-01

87

Astrophysical applications of Delbrück scattering: Dust scattered gamma radiation from gamma ray bursts  

NASA Astrophysics Data System (ADS)

A preliminary, and perhaps the first, study of astrophysical applications of Delbrück scattering in a gamma-ray emitting celestial object like a gamma-ray burst (GRB) has been made. At energies?100 MeV the elastic scattering of gamma-ray photons off the molecular dust surrounding the GRB site is dominated by Delbrück scattering. Expressions for Delbrück-scattered gamma-ray flux as a function of time has been obtained for a few selected energies by assuming a simple model of GRB. These are compared with Compton-scattered flux. At certain situations, interestingly, the former is found to exceed the latter for the first few milliseconds of the burst. The issue of detectability of Delbrück-scattered gamma-ray echo from the cloud of a GRB is discussed. Although it is observed that the detection of such an echo is not within the capability of the presently operating gamma-ray missions such as Fermi LAT, a rough estimate shows that one can be optimistic that future generation gamma-ray telescopes might be able to see such photons' contribution to the total flux.

Kunwar, B.; Bhadra, A.; Gupta, S. K. Sen

2014-02-01

88

Precise polarization measurements via detection of compton scattered electrons  

SciTech Connect

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

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

2014-01-01

89

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

90

Magnetic properties of Ga doped cobalt ferrite: Compton scattering study  

NASA Astrophysics Data System (ADS)

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

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

2014-04-01

91

Quantum radiation reaction effects in multiphoton Compton scattering  

E-print Network

Radiation reaction effects in the interaction of an electron and a strong laser field are investigated in the realm of quantum electrodynamics. We identify quantum radiation reaction with the multiple photon recoils experienced by the laser-driven electron due to consecutive incoherent photon emissions. After determining a quantum radiation dominated regime, we demonstrate how in this regime quantum signatures of radiation reaction strongly affect multiphoton Compton scattering spectra and that they could be measurable in principle with presently available laser technology.

A. Di Piazza; K. Z. Hatsagortsyan; C. H. Keitel

2010-11-24

92

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

93

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

94

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

95

Testing photons' Bose-Einstein statistics with Compton scattering  

SciTech Connect

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

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

2010-11-15

96

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

97

Measurement of deeply virtual Compton scattering at HERA  

Microsoft Academic Search

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

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

2003-01-01

98

Magnetic properties of Ga doped cobalt ferrite: Compton scattering study  

SciTech Connect

We present the spin momentum density of Ga doped CoFe{sub 2}O{sub 4} at 100 K using magnetic Compton scattering. The measurement has been performed using circularly polarized synchrotron radiations of 182.65 keV at SPring8, Japan. The experimental profile is decomposed into its constituent profile to determine the spin moment at individual sites. Co atom has the maximum contribution (about 58%) in the total spin moment of the doped CoFe{sub 2}O{sub 4}.

Sharma, Arvind, E-mail: arvind.phd.swm@gmail.com; Mund, H. S.; Ahuja, B. L. [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur-313001 (India); Sahariya, Jagrati [Department of Physics, Manipal University, Jaipur-303007 (India); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

2014-04-24

99

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

100

Laser pulse-shape dependence of Compton scattering  

NASA Astrophysics Data System (ADS)

Compton scattering of short and ultra short (sub-cycle) laser pulses off mildly relativistic electrons is considered within a QED framework. The temporal shape of the pulse is essential for the differential cross section as a function of the energy of the scattered photon at fixed observation angle. The partly integrated cross section is sensitive to the non-linear dynamics resulting in a large enhancement of the cross section for short and, in particular, for ultra-short flat-top pulse envelopes which can reach several orders of magnitude, as compared with the case of a long pulse. Such effects can be studied experimentally and must be taken into account in Monte-Carlo transport simulations of the interaction of electrons and photons in a strong laser field.

Titov, Alexander I.; Kämpfer, Burkhard; Shibata, Takuya; Hosaka, Atsushi; Takabe, Hideaki

2014-10-01

101

Laser pulse-shape dependence of Compton scattering  

E-print Network

Compton scattering of short and ultra short (sub-cycle) laser pulses off mildly relativistic electrons is considered within a QED framework. The temporal shape of the pulse is essential for the differential cross section as a function of the energy of the scattered photon at fixed observation angle. The partly integrated cross section is sensitive to the non-linear dynamics resulting in a large enhancement of the cross section for short and, in particular, for ultra-short flat-top pulse envelopes which can reach several orders of magnitude, as compared with the case of a long pulse. Such effects can be studied experimentally and must be taken into account in Monte-Carlo/transport simulations of %$e^+e^-$ pair production in the interaction of electrons and photons in a strong laser field.

Alexander I. Titov; Burkhard Kampfer; Takuya Shibata; Atsushi Hosaka; Hideaki Takabe

2014-08-05

102

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

103

Resonant Cyclotron Scattering and Comptonization in Neutron Star Magnetospheres  

E-print Network

Resonant cyclotron scattering of the surface radiation in the magnetospheres of neutron stars may considerably modify the emergent spectra and impede efforts to constraint neutron star properties. Resonant cyclotron scattering by a non-relativistic warm plasma in an inhomogeneous magnetic field has a number of unusual characteristics: (i) in the limit of high resonant optical depth, the cyclotron resonant layer is half opaque, in sharp contrast to the case of non-resonant scattering. (ii) The transmitted flux is on average Compton up-scattered by ~ $1+ 2 beta_T$, where $\\beta_T$ is the typical thermal velocity in units of the velocity of light; the reflected flux has on average the initial frequency. (iii) For both the transmitted and reflected fluxes the dispersion of intensity decreases with increasing optical depth. (iv) The emergent spectrum is appreciably non-Plankian while narrow spectral features produced at the surface may be erased. We derive semi-analytically modification of the surface Plankian emission due to multiple scattering between the resonant layers and apply the model to anomalous X-ray pulsar 1E 1048.1--5937. Our simple model fits just as well as the ``canonical'' magnetar spectra model of a blackbody plus power-law.

Maxim Lyutikov; Fotis P. Gavriil

2005-07-22

104

Astrophysical gamma-ray production by inverse Compton interactions of relativistic electrons. III - Cutoff effect for inverse Compton spectra applied to the case of the hard X-ray and gamma-ray emission of NGC 4151  

Microsoft Academic Search

The recently reported spectral features of NGC 4151 in the hard X-ray and gamma-ray energy range are analyzed. A two-component emission model is suggested in which the ultraviolet and soft Xray photons (E 20 keV) are scattered by relativistic electrons via the inverse Compton process into the hard X-ray and y-ray regime. It is shown that the rather fiat, hard

R. Schlickeiser

1980-01-01

105

Observations of GRB 990123 by the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

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

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

1999-01-01

106

Observation of the Higgs Boson of strong interaction via Compton scattering by the nucleon  

E-print Network

It is shown that the Quark-Level Linear $\\sigma$ Model (QLL$\\sigma$M) leads to a prediction for the diamagnetic term of the polarizabilities of the nucleon which is in excellent agreement with the experimental data. The bare mass of the $\\sigma$ meson is predicted to be $m_\\sigma=666$ MeV and the two-photon width $\\Gamma(\\sigma\\to\\gamma\\gamma)=(2.6\\pm 0.3)$ keV. It is argued that the mass predicted by the QLL$\\sigma$M corresponds to the $\\gamma\\gamma\\to\\sigma\\to NN$ reaction, i.e. to a $t$-channel pole of the $\\gamma N\\to N\\gamma$ reaction. Large -angle Compton scattering experiments revealing effects of the $\\sigma$ meson in the differential cross section are discussed. Arguments are presented that these findings may be understood as an observation of the Higgs boson of strong interaction while being part of the constituent quark.

Martin Schumacher

2010-03-15

107

OBSERBATION OF HIGH INTENSITY X-RAYS IN INVERSE COMPTON SCATTERING EXPERIMENT  

E-print Network

OBSERBATION OF HIGH INTENSITY X-RAYS IN INVERSE COMPTON SCATTERING EXPERIMENT S. Kashiwagi, M the first results of high intensity x-ray generation using Inverse Laser Compton scattering. This experiment Facility (ATF) in September 1999.The ATF is an accelerator and beam physics user facility. The 3.5 ps x-ray

108

Compton Gamma Ray Observatory: Lessons Learned in Propulsion  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

109

Is the high-energy emission from Centaurus A compton-scattered jet radiation?  

NASA Astrophysics Data System (ADS)

We consider whether the hard X-ray and soft gamma-ray emission from Centaurus A is beamed radiation from the active nucleus that is Compton-scattered into our line of sight. We derive the spectrum and degree of polarization of scattered radiation when incident beamed radiation is scattered from a cold (kT much less than mec2) electron cloud moving with bulk relativistic motion along the jet axis, and calculate results for an unpolarized, highly beamed incident power-law photon source. We fit the Oriented Scintillation Spectrometer Experiment (OSSE) data from Centaurus A with this model and find that if the scatterers are not moving relativistically, then the angle the jet makes with respect to our line of sight is 61 deg +/- 5 deg. We predict a high degree of polarization of the scattered radiation below approximately 300 keV. Future measurements with X-ray and gamma-ray polarimeters could be used to constrain or rule out such a scenario.

Skibo, J. B.; Dermer, C. D.; Kinzer, R. L.

1994-05-01

110

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

111

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

Microsoft Academic Search

As a prototype of the Shanghai Laser Electron Gamma Source in the Shanghai Synchrotron Radiation Facility, an x-ray source based on laser-Compton scattering (LCS) has been installed at the terminal of the 100 MeV linac of the Shanghai Institute of Applied Physics. LCS x-rays are generated by interactions between Q-switched Nd:yttrium aluminum garnet laser pulses [with wavelength of 1064 nm

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

2010-01-01

112

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

113

Real Compton Scattering on Proton at High Momentum Transfers  

SciTech Connect

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

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

2005-06-01

114

Longitudinal Target-Spin Asymmetries for Deeply Virtual Compton Scattering  

NASA Astrophysics Data System (ADS)

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for e p ?e'p'? events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q2 , xB, t , and ? , for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions.

Seder, E.; Biselli, A.; Pisano, S.; Niccolai, S.; Smith, G. D.; Joo, K.; Adhikari, K.; Amaryan, M. J.; Anderson, M. D.; Anefalos Pereira, S.; Avakian, H.; Battaglieri, M.; Bedlinskiy, I.; Bono, J.; Boiarinov, S.; Bosted, P.; Briscoe, W.; Brock, J.; Brooks, W. K.; Bültmann, S.; Burkert, V. D.; Carman, D. S.; Carlin, C.; Celentano, A.; Chandavar, S.; Charles, G.; Colaneri, L.; Cole, P. L.; Contalbrigo, M.; Crabb, D.; Crede, V.; D'Angelo, A.; Dashyan, N.; De Vita, R.; De Sanctis, E.; Deur, A.; Djalali, C.; Doughty, D.; Dupre, R.; El Fassi, L.; Elouadrhiri, L.; Eugenio, P.; Fedotov, G.; Fegan, S.; Filippi, A.; Fleming, J. A.; Fradi, A.; Garillon, B.; Garçon, M.; Gevorgyan, N.; Ghandilyan, Y.; Giovanetti, K. L.; Girod, F. X.; Goetz, J. T.; Gohn, W.; Gothe, R. W.; Griffioen, K. A.; Guegan, B.; Guidal, M.; Guo, L.; Hafidi, K.; Hakobyan, H.; Hanretty, C.; Harrison, N.; Hattawy, M.; Hirlinger Saylor, N.; Holtrop, M.; Hughes, S. M.; Ilieva, Y.; Ireland, D. G.; Ishkhanov, B. S.; Isupov, E. L.; Jo, H. S.; Joosten, S.; Keith, C. D.; Keller, D.; Khachatryan, G.; Khandaker, M.; Kim, A.; Kim, W.; Klein, A.; Klein, F. J.; Koirala, S.; Kubarovsky, V.; Kuhn, S. E.; Lenisa, P.; Livingston, K.; Lu, H. Y.; MacGregor, I. J. D.; Markov, N.; Mayer, M.; McKinnon, B.; Meekins, D. G.; Mineeva, T.; Mirazita, M.; Mokeev, V.; Montgomery, R.; Moody, C. I.; Moutarde, H.; Movsisyan, A.; Munoz Camacho, C.; Nadel-Turonski, P.; Niculescu, I.; Osipenko, M.; Ostrovidov, A. I.; Paolone, M.; Pappalardo, L. L.; Park, K.; Park, S.; Pasyuk, E.; Peng, P.; Phelps, W.; Pogorelko, O.; Price, J. W.; Prok, Y.; Protopopescu, D.; Puckett, A. J. R.; Ripani, M.; Rizzo, A.; Rosner, G.; Rossi, P.; Roy, P.; Sabatié, F.; Salgado, C.; Schott, D.; Schumacher, R. A.; Senderovich, I.; Simonyan, A.; Skorodumina, I.; Sokhan, D.; Sparveris, N.; Stepanyan, S.; Stoler, P.; Strakovsky, I. I.; Strauch, S.; Sytnik, V.; Taiuti, M.; Tang, W.; Tian, Y.; Ungaro, M.; Voskanyan, H.; Voutier, E.; Walford, N. K.; Watts, D. P.; Wei, X.; Weinstein, L. B.; Wood, M. H.; Zachariou, N.; Zana, L.; Zhang, J.; Zonta, I.; CLAS Collaboration

2015-01-01

115

Longitudinal target-spin asymmetries for deeply virtual compton scattering.  

PubMed

A measurement of the electroproduction of photons off protons in the deeply inelastic regime was performed at Jefferson Lab using a nearly 6 GeV electron beam, a longitudinally polarized proton target, and the CEBAF Large Acceptance Spectrometer. Target-spin asymmetries for ep?e^{'}p^{'}? events, which arise from the interference of the deeply virtual Compton scattering and the Bethe-Heitler processes, were extracted over the widest kinematics in Q^{2}, x_{B}, t, and ?, for 166 four-dimensional bins. In the framework of generalized parton distributions, at leading twist the t dependence of these asymmetries provides insight into the spatial distribution of the axial charge of the proton, which appears to be concentrated in its center. These results also bring important and necessary constraints for the existing parametrizations of chiral-even generalized parton distributions. PMID:25658994

Seder, E; Biselli, A; Pisano, S; Niccolai, S; Smith, G D; Joo, K; Adhikari, K; Amaryan, M J; Anderson, M D; Anefalos Pereira, S; Avakian, H; Battaglieri, M; Bedlinskiy, I; Bono, J; Boiarinov, S; Bosted, P; Briscoe, W; Brock, J; Brooks, W K; Bültmann, S; Burkert, V D; Carman, D S; Carlin, C; Celentano, A; Chandavar, S; Charles, G; Colaneri, L; Cole, P L; Contalbrigo, M; Crabb, D; Crede, V; D'Angelo, A; Dashyan, N; De Vita, R; De Sanctis, E; Deur, A; Djalali, C; Doughty, D; Dupre, R; El Fassi, L; Elouadrhiri, L; Eugenio, P; Fedotov, G; Fegan, S; Filippi, A; Fleming, J A; Fradi, A; Garillon, B; Garçon, M; Gevorgyan, N; Ghandilyan, Y; Giovanetti, K L; Girod, F X; Goetz, J T; Gohn, W; Gothe, R W; Griffioen, K A; Guegan, B; Guidal, M; Guo, L; Hafidi, K; Hakobyan, H; Hanretty, C; Harrison, N; Hattawy, M; Hirlinger Saylor, N; Holtrop, M; Hughes, S M; Ilieva, Y; Ireland, D G; Ishkhanov, B S; Isupov, E L; Jo, H S; Joosten, S; Keith, C D; Keller, D; Khachatryan, G; Khandaker, M; Kim, A; Kim, W; Klein, A; Klein, F J; Koirala, S; Kubarovsky, V; Kuhn, S E; Lenisa, P; Livingston, K; Lu, H Y; MacGregor, I J D; Markov, N; Mayer, M; McKinnon, B; Meekins, D G; Mineeva, T; Mirazita, M; Mokeev, V; Montgomery, R; Moody, C I; Moutarde, H; Movsisyan, A; Munoz Camacho, C; Nadel-Turonski, P; Niculescu, I; Osipenko, M; Ostrovidov, A I; Paolone, M; Pappalardo, L L; Park, K; Park, S; Pasyuk, E; Peng, P; Phelps, W; Pogorelko, O; Price, J W; Prok, Y; Protopopescu, D; Puckett, A J R; Ripani, M; Rizzo, A; Rosner, G; Rossi, P; Roy, P; Sabatié, F; Salgado, C; Schott, D; Schumacher, R A; Senderovich, I; Simonyan, A; Skorodumina, I; Sokhan, D; Sparveris, N; Stepanyan, S; Stoler, P; Strakovsky, I I; Strauch, S; Sytnik, V; Taiuti, M; Tang, W; Tian, Y; Ungaro, M; Voskanyan, H; Voutier, E; Walford, N K; Watts, D P; Wei, X; Weinstein, L B; Wood, M H; Zachariou, N; Zana, L; Zhang, J; Zonta, I

2015-01-23

116

Development of Gamma-Ray Compton Imager Using Room-Temperature 3-D Position Sensitive Semiconductor Detectors  

SciTech Connect

During the three years of this project, two 3-dimensional position sensitive CdZnTe spectrometers were upgraded in collaboration with Johns Hopkins University Applied Physics Laboratory. A prototype Compton-scattering gamma-ray imager was assembled using the two upgraded CdZnTe detectors. The performance of both gamma-ray spectrometers were individually tested. The angular resolution and detection sensitivity of the imaging system were measured using both a point and a line-shaped 137 Cs radiation source. The measurement results are consistent with that obtained from Monte-Carlo simulations performed during the early phase of the project.

Zhong He; David Whe; Glenn Knoll

2003-05-14

117

Compton scattering imaging of a working battery using synchrotron high-energy X-rays  

PubMed Central

Results of studies on Compton scattering imaging using synchrotron high-energy X-rays are reported. The technique is applied to a discharging coin cell, and the intensity of Compton scattered X-rays from the inside of the cell has been measured as a function of position and time. The position–time intensity map captures the migration of lithium ions in the positive electrode and reveals the structural change due to the volume expansion of the electrode. This experiment is a critical step in developing synchrotron-based Compton scattering imaging for electrochemical cells at a product level. PMID:25537603

Itou, Masayoshi; Orikasa, Yuki; Gogyo, Yuma; Suzuki, Kosuke; Sakurai, Hiroshi; Uchimoto, Yoshiharu; Sakurai, Yoshiharu

2015-01-01

118

Compton scattering imaging of a working battery using synchrotron high-energy X-rays.  

PubMed

Results of studies on Compton scattering imaging using synchrotron high-energy X-rays are reported. The technique is applied to a discharging coin cell, and the intensity of Compton scattered X-rays from the inside of the cell has been measured as a function of position and time. The position-time intensity map captures the migration of lithium ions in the positive electrode and reveals the structural change due to the volume expansion of the electrode. This experiment is a critical step in developing synchrotron-based Compton scattering imaging for electrochemical cells at a product level. PMID:25537603

Itou, Masayoshi; Orikasa, Yuki; Gogyo, Yuma; Suzuki, Kosuke; Sakurai, Hiroshi; Uchimoto, Yoshiharu; Sakurai, Yoshiharu

2015-01-01

119

Simplified Formulae System for Resonant Inverse Compton Scattering of a Fast Electron in an Intense Magnetic Field  

NASA Technical Reports Server (NTRS)

We present simple analytical formulae for the emission spectrum and total power of a special kind of resonant inverse Compton scattering (RICS) of a relativistic electron in an intense magnetic field. In contrast with the available formulae system, we obtain a markedly simplified one based on the semiclassical quantum theory, which is more understandable for people who are unfamiliar with quantum electrodynamics. We show that the RICS process, under an appropriate 'accommodation condition' derived in this paper, is predominantly much more efficient than the coexistent ordinary inverse Compton scattering, and produces highly beamed high-frequency radiation with moderately good monochromaticity. Our formulae are simple to use - thus offering a lucid physical intuition for the theory - and may find wide applications in hard X-ray and gamma-ray astrophysics.

You, J. H.; Chen, W. P.; Zhang, S. N.; Chen, L.; Liu, D.; Chou, C. K.

2003-01-01

120

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

SciTech Connect

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

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

2006-08-01

121

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

122

Deeply virtual Compton scattering and generalized parton distributions at CLAS?  

NASA Astrophysics Data System (ADS)

The exclusive electroproduction of real photons and mesons at high momentum transfer allows us to access the Generalized Parton Distributions (GPDs). The formalism of the GPDs provides a unified description of the hadronic structure in terms of quark and gluonic degrees of freedom. In particular, the Deeply Virtual Compton Scattering (DVCS), ep ? e'p'? , is one of the key reactions to determine the GPDs experimentally, as it is the simplest process that can be described in terms of GPDs. A dedicated experiment to study DVCS has been carried out in Hall B at Jefferson Lab. Beam-spin asymmetries, resulting from the interference of the Bethe-Heitler process and DVCS have been extracted over the widest kinematic range ever accessed for this reaction ( 1.2 < Q 2 < 3.7 (GeV/ c 2, 0.09 < - t < 1.3 (GeV/ c 2, 0.13 < x B < 0.46 . In this paper, the results obtained experimentally are shown and compared to GPD parametrizations.

Niccolai, S.

2008-11-01

123

Deeply virtual Compton Scattering cross section measured with CLAS  

SciTech Connect

The Generalized Parton Distributions (GPDs) provide a new description of nucleon structure in terms of its elementary constituents, the quarks and the gluons. Including and extending the information provided by the form factors and the parton distribution functions, they describe the correlation between the transverse position and the longitudinal momentum fraction of the partons in the nucleon. Deeply Virtual Compton Scattering (DVCS), the electroproduction of a real photon on a single quark in the nucleon eN --> e'N'g, is the exclusive process most directly interpretable in terms of GPDs. A dedicated experiment to study DVCS with the CLAS detector at Jefferson Lab has been carried out using a 5.9-GeV polarized electron beam and an unpolarized hydrogen target, allowing us to collect DVCS events in the widest kinematic range ever explored in the valence region : 1.0 < Q2 < 4.6 GeV2, 0.1 < xB < 0.58 and 0.09 < -t < 2.0 GeV2. In this paper, we show preliminary results of unpolarized cross sections and of polarized cross section differences for the DVCS channel.

Guegan, Baptistse [Institut de Physique Nucleaire, Orsay

2014-09-01

124

Low-Energy Theorem for Virtual Compton Scattering and Generalized Sum Rules of the Nucleon  

SciTech Connect

We formulate the low-energy theorem for virtual Compton scattering off a nucleon and examine its consequences for generalized nucleon polarizabilites. As a result of a new, model-independent definition of the low-energy limit for doubly virtual Compton scattering, all generalized sum rules of the nucleon have a continuous limit for real photons and obtain contributions from the t channel that were not included previously.

Gorchtein, Mikhail; Szczepaniak, Adam P. [Physics Department and Nuclear Theory Center, Indiana University, Bloomington, Indiana 47403 (United States)

2008-10-03

125

Gamma-Ray Polarization of the Synchrotron Self-compton Process from a Highly Relativistic Jet  

NASA Astrophysics Data System (ADS)

The high polarization observed in the prompt phase of some gamma-ray bursts invites extensive study of the emission mechanism. In this paper, we investigate the polarization properties of the synchrotron self-Compton (SSC) process from a highly relativistic jet. A magnetic-dominated, baryon-loaded jet ejected from the central engine travels with a large Lorentz factor. Shells with slightly different velocities collide with each other and produce shocks. The shocks accelerate electrons to a power-law distribution and, at the same time, magnify the magnetic field. Electrons move in the magnetic field and produce synchrotron photons. Synchrotron photons suffer from the Compton scattering (CS) process and then are detected by an observer located slightly off-axis. We analytically derive the formulae of photon polarization in the SSC process in two magnetic configurations: a magnetic field in the shock plane and perpendicular to the shock plane. We show that photons induced by the SSC process can be highly polarized, with the maximum polarization ? ~ 24% in the energy band [0.5, 5] MeV. The polarization depends on the viewing angles, peaking in the plane perpendicular to the magnetic field. In the energy band [0.05, 0.5] MeV, in which most ?-ray polarimeters are active, the polarization is about twice that in the Thomson limit, reaching ? ~ 20%. This implies that the Klein-Nishina effect, which is often neglected in the literature, should be carefully considered.

Chang, Zhe; Lin, Hai-Nan

2014-11-01

126

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

127

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

Microsoft Academic Search

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

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

1995-01-01

128

Registration of Abdominal CT and SPECT Images Using Compton Scatter Data  

Microsoft Academic Search

The present study investigates the possibility to utilize Compton scatter data for registration of abdominal SPECT images. A method for registration to CT is presented, based on principal component analysis and cross-correlation of binary images representing the interior of the patient. Segmentation of scatter images is performed with two methods, thresholding and a deformable contour method. To achieve similarity of

Katarina Sjögreen; Michael Ljungberg; Kjell Erlandsson; Lars Floreby; Sven-erik Strand

1997-01-01

129

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

SciTech Connect

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

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

2009-01-15

130

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

131

Electronic structure of lanthanum sesquioxide: A Compton scattering study  

NASA Astrophysics Data System (ADS)

We present the first-ever experimental and theoretical momentum densities of La2O3. The Compton line shape is measured using a 20 Ci 137Cs Compton spectrometer at an intermediate resolution with full width at half maximum of 0.34 a.u. The experimental Compton profile is compared with the theoretical electron momentum densities computed using linear combination of atomic orbitals (LCAO) method with density functional theory (DFT). It is seen that the generalized gradient approximation (GGA) within DFT reconciles better with the experiment than other DFT based approximations, validating the GGA approximation for rare-earth sesquioxides. The energy bands and density of states computed using LCAO calculations show its wide band gap nature which is in tune with the available reflectivity and photo-absorption data. In addition, Mulliken's population and charge density are also computed and discussed.

Sharma, Sonu; Sahariya, Jagrati; Arora, Gunjan; Ahuja, B. L.

2014-10-01

132

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

133

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

134

Compton Echoes from Gamma-Ray Bursts: Unveiling Misaligned Jets in Nearby Type Ib/c Supernovae  

E-print Network

There is now compelling evidence of a link between long-duration gamma-ray bursts (GRBs) and Type Ib/c supernovae (SNe). These core-collapse explosions are conjectured to radiate an anisotropic, beamed component associated with a decelerating, relativistic outflow and an unbeamed, isotropic component associated with the slowly expanding stellar debris. The anisotropic emission remains at a very low level until the Doppler cone of the beam intersects the observer's line of sight, making off-axis GRB jets directly detectable only at long wavelengths and late times. Circumstellar material, however, will Compton scatter the prompt gamma-ray and afterglow radiation flux and give rise to a reflection echo. We show that the Compton echo of a misaligned GRB carries an X-ray luminosity that may exceed by many orders of magnitude that produced by the underlying subrelativistic SN during the first few weeks. Bright scattering echoes may therefore provide a means for detecting a population of misaligned GRBs associated with nearby Type Ib/c SNe and yield crucial information on the environment surrounding a massive star at the time of its death. The question of whether the interpretation of GRB980425 as an ordinary GRB observed off-axis is consistent with the lack of an X-ray echo is addressed, along with the constraints derived on the possible existence of misaligned GRB jets in SN1993J, SN1994I, SN1999em, and SN2002ap.

Enrico Ramirez-Ruiz; Piero Madau

2004-05-06

135

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

136

Retardation, multipole, and relativistic kinematics effects for x- and ? -ray Compton scattering from K -shell electrons  

NASA Astrophysics Data System (ADS)

The aim of this paper is to obtain the right expression of the fully nonrelativistic K -shell Compton scattering amplitudes and cross sections. Using the Coulomb Green’s function method, we prove that by adequate analytical calculation of the nonrelativistic limit of the second order S -matrix element, it is possible to get Compton amplitudes which have no spurious singularities, as the old nonrelativistic result with retardation [M. Gavrila, Phys. Rev. A 6, 1348 (1972)] presents. A pole-free formula for Compton triply differential cross section, giving the right dependence on the angles of both the final electron and photon is obtained. This was possible by introducing relativistic kinematics terms and noticing that some of them cancel the retardation terms that generate the spurious poles. Consequently, the right nonrelativistic limit of the Compton amplitudes should be considered only after the cancellation of these terms. In this way the contributions corresponding to A2 and p•A operators present in the nonrelativistic Hamiltonian are correctly revealed. We show that good predictions are obtained for the whole Compton spectrum and any photon scattering angles for incoming photon energies ?1 up to ?Zm , if relativistic kinematics terms are included. The doubly differential cross section for Compton scattering of unpolarized photons from K -shell electrons is obtained by numerical integration over the angles of the final photon. Comparing our exact nonrelativistic formulae predictions for Compton scattering on intermediate and high atomic number targets, with experimental results and fully relativistic numerical evaluation of Bergstrom [Phys. Rev. A 48, 1134 (1993)], a good agreement within 10% is found for the whole spectrum and any scattering angle for incoming photon energy below 200 keV. This shows that spin effects are small for unexpected large incoming photon energies and high Z targets. Also, in the case of s bound states, the nonrelativistic wave function approximates fairly well the Dirac spinor even for large energies if momentum transfer is not too high. A second numerical integration of the doubly differential cross section over scattered photon energies was performed, giving the singly differential cross section. A good agreement with fully relativistic data is found for incoming photon energies up to 300 keV and any atomic target, if relativistic kinematics effects are taken into account. The same is true in the case of Compton scattering on lead at 661 keV for scattering angles less than 60°.

Costescu, A.; Spanulescu, S.

2006-02-01

137

SIMULATIONS AND STUDIES OF ELECTRON BEAM DYNAMICS UNDER COMPTON BACK-SCATTERING FOR THE COMPACT X-RAY  

E-print Network

SIMULATIONS AND STUDIES OF ELECTRON BEAM DYNAMICS UNDER COMPTON BACK-SCATTERING FOR THE COMPACT X- tions of a relativistic electron bunch in the compact storage ring ThomX (50 MeV), which is under] is a project of a compact high flux X-ray source based on the Compton scattering of laser photons

Boyer, Edmond

138

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

NASA Astrophysics Data System (ADS)

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

El Abd, A.

2014-01-01

139

Electronic properties and Compton scattering studies of monoclinic tungsten dioxide  

NASA Astrophysics Data System (ADS)

We present the first ever Compton profile measurement of WO2 using a 20 Ci 137Cs ?-ray source. The experimental data have been used to test different approximations of density functional theory in linear combination of atomic orbitals (LCAO) scheme. It is found that theoretical Compton profile deduced using generalized gradient approximation (GGA) gives a better agreement than local density approximation and second order GGA. The computed energy bands, density of states and Mulliken?s populations (MP) data confirm a metal-like behavior of WO2. The electronic properties calculated using LCAO approach are also compared with those obtained using full potential linearized augmented plane wave method. The nature of bonding in WO2 is also compared with isoelectronic WX2 (X=S, Se) compounds in terms of equal-valence-electron-density profiles and MP data, which suggest an increase in ionic character in the order WSe2?WS2?WO2.

Heda, N. L.; Ahuja, Ushma

2015-01-01

140

Evidence for Narrow Resonant Structures at $W ~\\sim 1.68$ and $W \\sim 1.72$ GeV in Real Compton Scattering off the Proton  

E-print Network

First measurement of the beam asymmetry $\\Sigma$ for Compton scattering off the proton in the energy range $E_{\\gamma}=0.85 - 1.25$ GeV is presented. The data reveals two narrow structures at $E_{\\gamma}= 1.036$ and $E_{\\gamma}=1.119$ GeV. They may signal either narrow resonances with the masses near $1.68$ and $1.72$ GeV, or can be generated by the sub-threshold $K\\Lambda$ and $\\omega p$ production. Their decisive identification requires additional theoretical and experimental efforts.

Kuznetsov, V; Bellini, V; Gervino, G; Ghio, F; Giardina, G; Kim, W; Mandaglio, G; Sperduto, M L; Sutera, C

2015-01-01

141

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.

142

Theory Viewpoint on Extracting Nucleon Polarisabilities in Low-Energy Compton Scattering  

E-print Network

During the workshop "Compton Scattering off Protons and Light Nuclei: pinning down the nucleon polarisabilities" (ECT*, Trento, Italy, 29 July -- 2 August 2013, http://www.ectstar.eu/node/98), recent developments had been reviewed in experimental and theoretical studies of real and virtual Compton scattering, static and generalized dipole scalar and spin polarisabilities of nucleons, as well as related phenomena in physics of muonic atoms. A vivid topic at the workshop was pathways towards the most precise extraction of the static polarisabilities from low-energy Compton cattering---including pertinent theoretical uncertainties. Being asked by our experimental colleagues, we prepared during the workshop a short letter with conclusions of the discussion, emphasising future prospects.

Harald W. Griesshammer; Anatoly I. L'vov; Judith A. McGovern; Vladimir Pascalutsa; Barbara Pasquini; Daniel R. Phillips

2014-09-04

143

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

144

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

145

An analytic reconstruction for the Compton scattering tomography in a plane  

NASA Astrophysics Data System (ADS)

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

Palamodov, V. P.

2011-12-01

146

Radon transforms on generalized Cormack's curves and a new Compton scatter tomography modality  

E-print Network

Radon transforms on generalized Cormack's curves and a new Compton scatter tomography modality T. T that Radon transforms defined on two remarkable families of curves in the plane are invertible and admit is invariant under geometric inversion. A derivation of the analytic inverse formula of the corresponding Radon

Paris-Sud XI, Université de

147

A simple and fast method for computing the relativistic Compton Scattering Kernel for radiative transfer  

NASA Technical Reports Server (NTRS)

The Klein-Nishina differential cross section averaged over a relativistic Maxwellian electron distribution is analytically reduced to a single integral, which can then be rapidly evaluated in a variety of ways. A particularly fast method for numerically computing this single integral is presented. This is, to the authors' knowledge, the first correct computation of the Compton scattering kernel.

Kershaw, David S.; Prasad, Manoj K.; Beason, J. Douglas

1986-01-01

148

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

E-print Network

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

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

2014-03-17

149

Nuclear Compton scattering from 12C and bound-nucleon polarizabilities  

Microsoft Academic Search

Compton scattering cross sections from 12C have been measured at scattering angles of thetagamma=35°-150° using tagged photons of Egamma=84-105 MeV. Attempts to extract nucleon polarizabilities from the data were hampered by model ambiguities. These included uncertainties in the strength of the electric quadrupole and quasideuteron total photon absorption channels, and in the parametrizations of meson-exchange effects and nuclear form factors.

B. J. Warkentin; D. L. Hornidge; R. Igarashi; J. C. Bergstrom; E. L. Hallin; N. R. Kolb; R. E. Pywell; D. M. Skopik; J. M. Vogt; G. Feldman

2001-01-01

150

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

151

How the hydrogen bond in NH4F is revealed with Compton scattering  

NASA Astrophysics Data System (ADS)

In order to probe electron wave functions involved in the bonding of NH4F , we have performed Compton scattering experiments in an oriented single crystal and in a powder. Ab initio calculations of the Compton profiles for NH4F and NH4Cl are used to enlighten the nature of the bonds in the NH4F crystal. As a consequence, we are able to show significant charge transfer in the ammonium ion which is not observable using other methods. Our study provides a compelling proof for hydrogen bond formation in NH4F .

Barbiellini, B.; Bellin, Ch.; Loupias, G.; Buslaps, T.; Shukla, A.

2009-04-01

152

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

Microsoft Academic Search

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

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

1993-01-01

153

Electromagnetic Form Factors of the Nucleon and Compton Scattering  

E-print Network

We review the experimental and theoretical status of elastic electron scattering and elastic low-energy photon scattering (with both real and virtual photons) from the nucleon. As a consequence of new experimental facilities and new theoretical insights, these subjects are advancing with unprecedented precision. These reactions provide many important insights into the spatial distributions and correlations of quarks in the nucleon.

Charles Earl Hyde-Wright; Kees de Jager

2005-07-01

154

INVERSE-COMPTON CONTRIBUTION TO THE STAR-FORMING EXTRAGALACTIC GAMMA-RAY BACKGROUND  

SciTech Connect

Fermi has resolved several star-forming galaxies, but the vast majority of the star-forming universe is unresolved, and thus contributes to the extragalactic gamma-ray background (EGB). Here, we calculate the contribution of star-forming galaxies to the EGB in the Fermi range from 100 MeV to 100 GeV due to inverse-Compton (IC) scattering of the interstellar photon field by cosmic-ray electrons. We first construct one-zone models for individual star-forming galaxies assuming that supernovae power the acceleration of cosmic rays. We develop templates for both normal and starburst galaxies, accounting for differences in the cosmic-ray electron propagation and in the interstellar radiation fields. For both types of star-forming galaxies, the same IC interactions leading to gamma rays also substantially contribute to the energy loss of the high-energy cosmic-ray electrons. Consequently, a galaxy's IC emission is determined by the relative importance of IC losses in the cosmic-ray electron energy budget ({sup p}artial calorimetry{sup )}. We calculate the cosmological contribution of star-forming galaxies to the EGB using our templates and the cosmic star formation rate distribution. For all of our models, we find that the IC EGB contribution is almost an order of magnitude less than the peak of the emission due to cosmic-ray ion interactions (mostly pionic p{sub cr} p{sub ism} {yields} {pi}{sup 0} {yields} {gamma}{gamma}); even at the highest Fermi energies, IC is subdominant. The flatter IC spectrum increases the high-energy signal of the pionic+IC sum, bringing it closer to the EGB spectral index observed by Fermi. Partial calorimetry ensures that the overall IC signal is relatively well constrained, with only uncertainties in the amplitude and spectral shape for plausible model choices. We conclude with a brief discussion on how the pionic spectral feature and other methods can be used to measure the star-forming component of the EGB.

Chakraborty, Nachiketa [Department of Astronomy, University of Illinois, Urbana, IL (United States); Fields, Brian D. [Also, Department of Physics, University of Illinois, Urbana, IL (United States)

2013-08-20

155

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

SciTech Connect

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

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

2012-07-31

156

Supercontinuum and ultra-short pulse generation from nonlinear Thomson and Compton scattering  

E-print Network

Nonlinear Thomson and Compton processes, in which energetic electrons collide with an intense optical pulse, are investigated in the framework of classical and quantum electrodynamics. Spectral modulations of the emitted radiation, appearing as either oscillatory or pulsating structures, are observed and explained. It is shown that both processes generate a bandwidth radiation spanning the range of few MeV, which occurs in a small cone along the propagation direction of the colliding electrons. Most importantly, these broad bandwidth structures are temporarily coherent which proves that Thomson and Compton processes lead to generation of a supercontinuum. It is demonstrated that the radiation from the supercontinuum can be synthesized into zeptosecond (possibly even yoctosecond) pulses. Thus, confirming that Thomson and Compton scattering can be used as novel sources of an ultra-short radiation, opening routes to new physical domains for strong laser physics.

Krajewska, K; Kami?ski, J Z

2013-01-01

157

Supercontinuum and ultra-short pulse generation from nonlinear Thomson and Compton scattering  

E-print Network

Nonlinear Thomson and Compton processes, in which energetic electrons collide with an intense optical pulse, are investigated in the framework of classical and quantum electrodynamics. Spectral modulations of the emitted radiation, appearing as either oscillatory or pulsating structures, are observed and explained. It is shown that both processes generate a bandwidth radiation spanning the range of few MeV, which occurs in a small cone along the propagation direction of the colliding electrons. Most importantly, these broad bandwidth structures are temporarily coherent which proves that Thomson and Compton processes lead to generation of a supercontinuum. It is demonstrated that the radiation from the supercontinuum can be synthesized into zeptosecond (possibly even yoctosecond) pulses. Thus, confirming that Thomson and Compton scattering can be used as novel sources of an ultra-short radiation, opening routes to new physical domains for strong laser physics.

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

2013-11-19

158

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

159

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

160

One- and two-photon Compton scattering in strong magnetic fields  

NASA Technical Reports Server (NTRS)

Calculations are made of the Compton scattering cross section in a very strong magnetic field, such as encountered in pulsars, for arbitrary photon and electron energies. The effect of the vacuum polarization in the weak-field limit is included as well as the plasma polarizability. Radiative transitions between any pair of Landau levels are included as well as two-photon scattering. The latter process, due to the presence of the cyclotron resonance, becomes comparable to nonresonant one-photon scattering when excited final states are allowed, and acts as a source of photons which is more important than bremsstrahlung at low plasma densities.

Bussard, R. W.; Alexander, S. B.; Meszaros, P.

1986-01-01

161

Nuclear Instruments and Methods in Physics Research A 457 (2001) 203}211 Evaluation of a Compton scattering camera using  

E-print Network

scattering camera using 3-D position sensitive CdZnTe detectors Y.F. Du*, Z. He, G.F. Knoll, D.K. Wehe, W. Li, USA Received 22 May 2000; accepted 15 June 2000 Abstract A CZT Compton Camera (CCC) is being built imaging; 3-D position sensitive; Room-temperature CZT detector 1. Introduction Compton cameras have

He, Zhong

162

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

163

Nonlinear Compton scattering of ultrashort intense laser pulses  

SciTech Connect

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

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

2011-02-15

164

Nonlinear Compton scattering of ultrashort intense laser pulses  

NASA Astrophysics Data System (ADS)

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

Seipt, D.; Kämpfer, B.

2011-02-01

165

Balloon-borne experiment for observation of sub-MeV/MeV gamma-rays from Crab Nebula using an Electron Tracking Compton Camera  

NASA Astrophysics Data System (ADS)

In astronomy, the observations of gamma-ray in sub-MeV/MeV energy band is expected to provide much information of various high energy phenomena, for example, the nucleosynthesis in supernovae, the particle acceleration in active galactic nuclei, gamma-ray bursts, and the strong gravity potential of black holes. However, sufficient observation has not yet been achieved due to difficulties of Compton gamma-ray imaging and rejection of large radiation backgrounds produced by the interaction of cosmic rays with a satellite body. To advance the MeV gamma-ray astronomy, we have developed an Electron Tracking Compton Camera (ETCC) as a next-generation MeV gamma-ray telescope. In comparison with a classical Compton camera, the ETCC measures a three dimensional track of the Compton recoil electron in the gas detector, which makes it possible to restrict the arrival direction of each incident gamma-ray to arc segment and remove backgrounds strongly using the kinematics test of Compton scattering and the particle identification by energy loss rate of charged particle. We planned the balloon experiments “Sub-MeV gamma-ray Imaging Loaded-on-balloon Experiment” (SMILE) to check the performance of ETCC in space for the future satellite observation. We have already carried out the first balloon borne experiment in 2006 using a small size ETCC with a 10 times 10 times 15 cm(3) detection area (SMILE-I), and we observed successfully the fluxes of the diffuse cosmic and atmospheric gamma rays at an altitude of 35 km during a live time of 3 hours and reveal the good background rejection ability of an ETCC. As the next step of SMILE, we plan to observe bright celestial sources like Crab Nebula to verify the gamma-ray imaging ability of an ETCC (SMILE-II) at middle latitude in the northern hemisphere. We have already constructed the SMILE-II flight ETCC system using a large size ETCC with (30 cm)(3) detection area and completely upgraded data acquisition system for reducing the dead time and power consumption. Furthermore, we improved the data acquisition algorithm of electron tracking to improve the effective area of the ETCC. Now we have confirmed the performance of the SMILE-II flight ETCC system by ground-based experiments. With the obtained results, Crab Nebula can be detected by the ETCC with a significance above the 5 sigma level in several hours in a one day balloon flight experiment. In this paper, we will report the details of the SMILE-II project and the the performance of the SMILE-II flight ETCC.

Komura, Shotaro

166

Investigating the proton structure through polarization transfers in real Compton scattering processes at JLAB  

NASA Astrophysics Data System (ADS)

In the present work, preliminary results of the analysis of polarization transfers in real Compton scattering (RCS) performed in Hall-C at JLAB are presented, for data collected at large scattering angle (?cm=70o) in the experiment E07-002. A previous experiment, E99-114, has already demonstrated a complete inconsistence of its results with a pQCD mechanism at JLAB energy regime. This kind of experiment, therefore, is of crucial importance for understanding the nature of the reaction mechanism for such a simple process, involving a real photon. Furthermore, RCS experiments allow the extraction of Compton form factors and Generalized Parton Distributions (GPDs), the latter connected to the total angular momentum of the nucleon.

Fanelli, C.; Cisbani, E.; Hamilton, D.; Salmè, G.; Wojtsekhowski, B.

2014-06-01

167

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

SciTech Connect

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

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

2009-12-15

168

Investigating the proton structure through polarization transfers in real Compton scattering processes at JLAB  

SciTech Connect

In the present work, preliminary results of the analysis of polarization transfers in real Compton scattering (RCS) performed in Hall-C at JLAB are presented, for data collected at large scattering angle (?{sub cm}=70{degrees}) in the experiment E07-002. A previous experiment, E99-114, has already demonstrated a complete inconsistence of its results with a pQCD mechanism at JLAB energy regime. This kind of experiment, therefore, is of crucial importance for understanding the nature of the reaction mechanism for such a simple process, involving a real photon. Furthermore, RCS experiments allow the extraction of Compton form factors and Generalized Parton Distributions (GPDs), the latter connected to the total angular momentum of the nucleon.

Fanelli, Cristiano V. [INFN/Sanita, Roma, ITALY; Cisbani, Evaristo [INFN/Sanita, Roma, ITALY; Hamilton, David J. [Glasgow University; Salme, Giovanni [Instituto Nazionale de Fisica Nucleare, Italy; Wojtsekhowski, Bogdan B. [JLAB

2014-06-01

169

Study of the proton structure by measurements of polarization transfers in real Compton scattering at Jlab  

SciTech Connect

A preliminary analysis of polarization-transfer data at large scattering angle (70°), obtained in an experiment of real Compton scattering on proton, performed in Hall-C of Jefferson Lab, is presented. It is also discussed the relevance of this kind of experiments for shedding light on the non-perturbative structure of the proton, at low energy, and on the transition from the non-perturbative regime to the perturbative one, that occurs at high energy. Moreover, the possibility to extract Compton form factors and the Generalized Parton Distributions, one of the most promising theoretical tool to determine the total angular momentum contribution of quarks and gluons to nucleon spin, is emphasized.

Fanelli, Cristiano Fanelli; Cisbani, Evarostp; Hamilton, David; Salme, G.; Wojtsekhowski, Bogdan B. [JLAB

2014-03-01

170

In-Flight Calibration of the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory  

NASA Technical Reports Server (NTRS)

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

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

1998-01-01

171

Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz  

E-print Network

A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness ...

Bessuille, J.

172

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

E-print Network

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e, e'p)? exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at ...

Zhou, Z. -L.

173

Compton Effect  

NSDL National Science Digital Library

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

Palop, Jose I.

2010-12-12

174

An X-ray spectroscopy system and its application to the laser-Compton scattering experiments  

Microsoft Academic Search

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.

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

2010-01-01

175

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

176

A simple method for computing the relativistic Compton scattering kernel for radiative transfer  

NASA Technical Reports Server (NTRS)

Correct computation of the Compton scattering kernel (CSK), defined to be the Klein-Nishina differential cross section averaged over a relativistic Maxwellian electron distribution, is reported. The CSK is analytically reduced to a single integral, which can then be rapidly evaluated using a power series expansion, asymptotic series, and rational approximation for sigma(s). The CSK calculation has application to production codes that aim at understanding certain astrophysical, laser fusion, and nuclear weapons effects phenomena.

Prasad, M. K.; Kershaw, D. S.; Beason, J. D.

1986-01-01

177

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

178

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

NASA Technical Reports Server (NTRS)

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 identification of this object as a quasar. The differential photon spectrum is well represented by a power law with an exponent of 2.56 +/- 0.09 and a photon intensity above 100 MeV of (8.4 +/- 1.0) x 10 exp -7 photons sq cm/s. There is evidence for time variability on a time scale of a few days.

Hunter, S. D.; Bertsch, D. L.; Dingus, B. L.; Fichtel, C. E.; Hartman, R. C.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

1993-01-01

179

An Investigation of the Isovector Giant Quadrupole Resonance in Bismuth-209 using Polarized Compton Scattering  

NASA Astrophysics Data System (ADS)

Giant multipole resonances are a fundamental property of nuclei and arise from the collective motion of the nucleons inside the nucleus. Careful studies of these resonances and their properties provides insight into the nature of nuclear matter and constraints which can be used to test our theories. An investigation of the Isovector Giant Quadrupole Resonance (IVGQR) in 209Bi has been preformed using the High Intensity gamma-ray Source (HI g? S) facility. Intense nearly monochromatic polarized g? -rays were incident upon a 209Bi target producing nuclear Compton scattered gamma-rays that were detected using the HI g? S NaI(Tl) Detector Array (HINDA). The HINDA array consists of six large (10"x10") NaI(Tl) core crystals, each surrounded by an optically segmented 3" thick NaI(Tl) annulus. The scattered gamma-rays both parallel and perpendicular to the plane of polarization were detected at scattering angles of 55° and 125° with respect to the beam axis. This was motivated by the realization that the term representing the interference between the electric dipole ( E1) and electric quadrupole (E2) amplitudes, which appears in the theoretical expression for the ratio of the polarized cross sections, has a sign difference between the forward and backward angles and also changes sign as the incident gamma-ray energy is scanned over the E2 resonance energy. The ratio of cross sections perpendicular and parallel to the plane of polarization of the incident gamma-ray were measured for thirteen different incident gamma-ray energies between 15 and 26 MeV at these two angles and used to extract the parameters of the IVGQR in 209Bi. The polarization ratio was calculated at 55° and 125° using a model consisting of E1 and E2 giant resonances as well as a modified Thomson scattering amplitude. The parameters of the E1 giant resonance came from previous measurements of the Giant Dipole Resonance (GDR) in 209Bi. The finite size of the nucleus was accounted for by introducing a charge form factor in the (modified) Thomson amplitude. This form factor was obtained from measurements of the charge density in inelastic electron scattering experiments. The resulting curves were fit to the data by varying the E2 parameters until a minimum value of the chi2 was found. The resulting parameters from the fit yield an IVGQR in 209Bi located at Eres = 23.0 +/- 0.13(stat)+/-0.25(sys) MeV with a width of Gamma = 3.9 +/- 0.7(stat)+/-1.3(sys) MeV and a strength of 0.56 +/- 0.04(stat)+/-0.10(sys) Isovector Giant Quadrupole Energy Weighted Sum Rules (IVQ-EWSRs). The ability to make precise measurements of the parameters of the IVGQR demonstrated by this work opens up new challenges to both experimental and theoretical work in nuclear structure. A detailed search for the missing sum rule strength in the case of 209Bi should be performed. In addition, a systematic study of a number of nuclei should be studied with this technique in order to carefully examine the A dependence of the energy, width and sum rule strength of the IVGQR as a function of the mass number A. The unique properties of the HI g? S facility makes it the ideal laboratory at which to perform these studies. Such a data base will provide more stringent tests of nuclear theory. The effective parameters of collective models can be fine tuned to account for such precision data. This should lead to new insights into the underlying interactions responsible for the nature of the IVGQR. Furthermore, with the recent advances in computational power and techniques, microscopic shell model based calculations should be possible and could lead to new insights into the underlying properties of nuclear matter which are responsible for the collective behavior evidenced by the existence and properties of the IVGQR.

Henshaw, Seth S.

180

Structured x-ray beams from twisted electrons by inverse Compton scattering of laser light  

E-print Network

The inverse Compton scattering of laser light on high-energetic twisted electrons is investigated with the aim to construct spatially structured x-ray beams. In particular, we analyze how the properties of the twisted electrons, such as the topological charge and aperture angle of the electron Bessel beam, affects the energy and angular distribution of scattered x-rays. We show that with suitably chosen initial twisted electron states one can synthesize tailor-made x-ray beam profiles with a well-defined spatial structure, in a way not possible with ordinary plane-wave electron beams.

D. Seipt; A. Surzhykov; S. Fritzsche

2014-07-28

181

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

182

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

NASA Astrophysics Data System (ADS)

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

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

2004-11-01

183

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

PubMed

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

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

2011-12-01

184

The diffuse galactic gamma radiation: The Compton contribution and component separation by energy interval and galactic coordinates  

NASA Technical Reports Server (NTRS)

The radiation to be expected from cosmic ray interactions with matter and photons was examined. Particular emphasis is placed on the Compton emission. Both the photon density in and near the visible region and that in the region are deduced from the estimates of the emission functions throughout the Galaxy. The blackbody radiation is also included in the estimate of the total Compton emission. The result suggests that the gamma ray Compton radiation from cosmic ray ineractions with galactic visible and infrared photons is substantially larger than previously believed.

Kniffen, D. A.; Fichtel, C.

1981-01-01

185

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

PubMed

In this paper, we study the feasibility of using the stochastic origin ensemble (SOE) algorithm for reconstructing images of secondary gammas emitted during proton radiotherapy from data measured with a three-stage Compton camera. The purpose of this study was to evaluate the quality of the images of the gamma rays emitted during proton irradiation produced using the SOE algorithm and to measure how well the images reproduce the distal falloff of the beam. For our evaluation, we performed a Monte Carlo simulation of an ideal three-stage Compton camera positioned above and orthogonal to a proton pencil beam irradiating a tissue phantom. Scattering of beam protons with nuclei in the phantom produces secondary gamma rays, which are detected by the Compton camera and used as input to the SOE algorithm. We studied the SOE reconstructed images as a function of the number of iterations, the voxel probability parameter, and the number of detected gammas used by the SOE algorithm. We quantitatively evaluated the capabilities of the SOE algorithm by calculating and comparing the normalized mean square error (NMSE) of SOE reconstructed images. We also studied the ability of the SOE reconstructed images to predict the distal falloff of the secondary gamma production in the irradiated tissue. Our results show that the images produced with the SOE algorithm converge in ~10,000 iterations, with little improvement to the image NMSE for iterations above this number. We found that the statistical noise of the images is inversely proportional to the ratio of the number of gammas detected to the SOE voxel probability parameter value. In our study, the SOE predicted distal falloff of the reconstructed images agrees with the Monte Carlo calculated distal falloff of the gamma emission profile in the phantom to within ±0.6 mm for the positions of maximum emission (100%) and 90%, 50% and 20% distal falloff of the gamma emission profile. We conclude that the SOE algorithm is an effective method for reconstructing images of a proton pencil beam from the data collected by an ideal Compton camera and that these images accurately model the distal falloff of secondary gamma emission during proton irradiation. PMID:22588144

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

2012-06-01

186

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

NASA Technical Reports Server (NTRS)

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

Psaltis, Dimitrios; Lamb, Frederick K.

1997-01-01

187

Time-resolved Compton scattering for a model fermion-boson system  

NASA Astrophysics Data System (ADS)

We study the scattering of a boson with a fermion with full spatial and temporal resolution based on the one-dimensional Yukawa Hamiltonian. In quantum field theory this interaction is described by the annihilation and creation of bosons with intermediate virtual particle states. We show that this process can be modeled in the center-of-mass frame by a scattering potential, permitting us to interpret the absorption and re-emission processes in quantum mechanical terms of a characteristic force. This Compton force between the fermion and boson is repulsive for large distances and attractive for shorter spacings. We also examine the periodic dynamics of a fermion and a boson that are spatially confined to a ring cavity in which they counterpropagate, enabling us to study interactions independent of the transients that characterize the (one-time) scattering event of two wave packets.

Wagner, R. E.; Su, Q.; Grobe, R.

2010-08-01

188

Time resolved Compton scattering for a model fermion-boson system  

NASA Astrophysics Data System (ADS)

We study the scattering of a boson with a fermion with full spatial and temporal resolution based on the one-dimensional Yukawa Hamiltonian. In quantum field theory this interaction is described by the annihilation and creation of bosons with intermediate virtual particle states. We show that this process can be modeled in the center of mass frame by a scattering potential, permitting us to interpret the absorption and re-emission processes in quantum mechanical terms of a characteristic force. This Compton force between the fermion and boson is repulsive for large distances and attractive for shorter spacings. We also examine the periodic dynamics of a fermion and a boson that are spatially confined to a ring-cavity in which they counter-propagate, enabling us to study interactions independent of the transients that characterize the (one-time) scattering event of two wavepackets.

Wagner, R.; Su, Q.; Grobe, R.

2011-06-01

189

Temporal synchronization of GHz repetition rate electron and laser pulses for the optimization of a compact inverse-Compton scattering x-ray source  

NASA Astrophysics Data System (ADS)

The operation of an inverse-Compton scattering source of x-rays or gamma-rays requires the precision alignment and synchronization of highly focused electron bunches and laser pulses at the collision point. The arrival times of electron and laser pulses must be synchronized with picosecond precision. We have developed an RF synchronization technique that reduces the initial timing uncertainty from 350 ps to less than 2 ps, greatly reducing the parameter space to be optimized while commissioning the x-ray source. We describe the technique and present measurements of its performance.

Hadmack, M. R.; Szarmes, E. B.; Madey, J. M. J.; Kowalczyk, J. M. D.

2015-02-01

190

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

191

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

NASA Astrophysics Data System (ADS)

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

Grießhammer, Harald W.

2013-08-01

192

An inverse Compton scattering (ICS) model of pulsar emission: III. polarization  

E-print Network

Qiao and his collaborators recently proposed an inverse Compton Scattering (ICS) model to explain radio emission of pulsars. In this paper, we investigate the polarization properties of pulsar emission in the model. First of all, using the lower frequency approximation, we derived the analytical amplitude of inverse Compton scattered wave of a single electron in strong magnetic field. We found that the out-going radio emission of a single relativistic electron scattering off the ``low frequency waves'' produced by gap-sparking should be linearly polarized and have no circular polarization at all. However, considering the coherency of the emission from a bunch of electrons, we found that the out-going radiation from the inner part of emission beam, i.e., that from the lower emission altitudes, prefers to have circular polarization. Computer simulations show that the polarization properties, such as the sense reversal of circular polarization near the pulse center, S-shape of position angle swing of the linear polarization, strong linear polarization in conal components, can be reproduced in the ICS model.

R. X. Xu; J. F. Liu; J. L. Han; G. J. Qiao

1999-11-15

193

An inverse Compton scattering (ICS) model of pulsar emission; 3, polarization  

E-print Network

Qiao and his collaborators recently proposed an inverse Compton Scattering (ICS) model to explain radio emission of pulsars. In this paper, we investigate the polarization properties of pulsar emission in the model. First of all, using the lower frequency approximation, we derived the analytical amplitude of inverse Compton scattered wave of a single electron in strong magnetic field. We found that the out-going radio emission of a single relativistic electron scattering off the ``low frequency waves'' produced by gap-sparking should be linearly polarized and have no circular polarization at all. However, considering the coherency of the emission from a bunch of electrons, we found that the out-going radiation from the inner part of emission beam, i.e., that from the lower emission altitudes, prefers to have circular polarization. Computer simulations show that the polarization properties, such as the sense reversal of circular polarization near the pulse center, S-shape of position angle swing of the linear ...

Xu, R X; Han, J L; Qiao, G J

1999-01-01

194

Compton Scattering and its Applications:. the Pleiades Femtosecond X-Ray Source at LLNL  

NASA Astrophysics Data System (ADS)

Remarkable developments in critical technologies including terawatt-class lasers using chirped-pulse amplification, high brightness photoinjectors, high-gradient accelerators, and superconducting linacs make it possible to design and operate compact, tunable, subpicosecond Compton scattering x-ray sources with a wide variety of applications. In such novel radiation sources, the collision between a femtosecond laser pulse and a low emittance relativistic electron bunch in a small (?m3) interaction volume produces Doppler-upshifted scattered photons with unique characteristics: the energy is tunable in the 5-500 keV range, the angular divergence of the beam is small (mrad), and the pulses are ultrashort (10 fs - 10 ps). Two main paths are currently being followed in laboratories worldwide: high peak brightness, using ultrahigh intensity femtosecond lasers at modest repetition rates, and high average brightness, using superconducting linac and high average power laser technology at MHz repetition rates. Targeted applications range from x-ray protein crystallography and high contrast medical imaging to femtosecond pump-probe and diffraction experiments. More exotic uses of such sources include the ?-? collider, NIF backlighting, nonlinear Compton scattering, and high-field QED. Theoretical considerations and experimental results will be discussed within this context.

Hartemann, F. V.; Brown, W. J.; Anderson, S. G.; Barty, C. P. J.; Betts, S. M.; Booth, R.; Crane, J. K.; Cross, R. R.; Fittinghoff, D. N.; Gibson, D. J.; Kuba, J.; Rupp, B.; Tremaine, A. M.; Springer, P. T.

2004-10-01

195

Measurement of Compton Scattering from the Deuteron and an Improved Extraction of the Neutron Electromagnetic Polarizabilities  

NASA Astrophysics Data System (ADS)

The electromagnetic polarizabilities of the nucleon are fundamental properties that describe its response to external electric and magnetic fields. They can be extracted from Compton-scattering data—and have been, with good accuracy, in the case of the proton. In contradistinction, information for the neutron requires the use of Compton scattering from nuclear targets. Here, we report a new measurement of elastic photon scattering from deuterium using quasimonoenergetic tagged photons at the MAX IV Laboratory in Lund, Sweden. These first new data in more than a decade effectively double the world data set. Their energy range overlaps with previous experiments and extends it by 20 MeV to higher energies. An analysis using chiral effective field theory with dynamical ? (1232 ) degrees of freedom shows the data are consistent with and within the world data set. After demonstrating that the fit is consistent with the Baldin sum rule, extracting values for the isoscalar nucleon polarizabilities, and combining them with a recent result for the proton, we obtain the neutron polarizabilities as ?n=[11.55 ±1.25 (stat)±0.2 (BSR )±0.8 (th )]×10-4 fm3 and ?n=[3.65 ?1.25 (stat)±0.2 (BSR )?0.8 (th )]×10-4 fm3 , with ?2=45.2 for 44 degrees of freedom.

Myers, L. S.; Annand, J. R. M.; Brudvik, J.; Feldman, G.; Fissum, K. G.; Grießhammer, H. W.; Hansen, K.; Henshaw, S. S.; Isaksson, L.; Jebali, R.; Kovash, M. A.; Lundin, M.; McGovern, J. A.; Middleton, D. G.; Nathan, A. M.; Phillips, D. R.; Schröder, B.; Stave, S. C.; Compton@Max-Lab Collaboration

2014-12-01

196

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

197

Finite-t and target-mass corrections to deeply virtual compton scattering.  

PubMed

We carry out the first complete calculation of kinematic power corrections ~t/Q(2) and ~m(2)/Q(2) to the helicity amplitudes of deeply virtual Compton scattering. This result removes an important source of uncertainties in the quantum chromodynamics predictions for intermediate momentum transfers Q(2) ~ 1-10 GeV(2) that are accessible in the existing and planned experiments. In particular, the finite-t corrections are significant and must be taken into account in the data analysis. PMID:23368308

Braun, V M; Manashov, A N; Pirnay, B

2012-12-14

198

Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering  

NASA Astrophysics Data System (ADS)

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

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

2006-12-01

199

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

200

Testing Models of Resonant Compton Scattering in X-Ray Pulsars  

NASA Technical Reports Server (NTRS)

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

Brainerd, Jerome J.

2000-01-01

201

Data acquisition and analysis for the energy-subtraction Compton scatter camera for medical imaging  

NASA Astrophysics Data System (ADS)

In response to the shortcomings of the Anger camera currently being used in conventional SPECT, particularly the trade-off between sensitivity and spatial resolution, a novel energy-subtraction Compton scatter camera, or the ESCSC, has been proposed. A successful clinical implementation of the ESCSC could revolutionize the field of SPECT. Features of this camera include utilization of silicon and CdZnTe detectors in primary and secondary detector systems, list-mode time stamping data acquisition, modular architecture, and post-acquisition data analysis. Previous ESCSC studies were based on Monte Carlo modeling. The objective of this work is to test the theoretical framework developed in previous studies by developing the data acquisition and analysis techniques necessary to implement the ESCSC. The camera model working in list-mode with time stamping was successfully built and tested thus confirming potential of the ESCSC that was predicted in previous simulation studies. The obtained data were processed during the post-acquisition data analysis based on preferred event selection criteria. Along with the construction of a camera model and proving the approach, the post-acquisition data analysis was further extended to include preferred event weighting based on the likelihood of a preferred event to be a true preferred event. While formulated to show ESCSC capabilities, the results of this study are important for any Compton scatter camera implementation as well as for coincidence data acquisition systems in general.

Khamzin, Murat Kamilevich

202

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. [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States)], E-mail: jdd@lanl.gov; Warsa, James S. [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States)], E-mail: warsa@lanl.gov; Lowrie, Robert B. [Computational Physics and Methods Group, Los Alamos National Laboratory, P.O. Box 1663, MS D409, Los Alamos, NM 87545 (United States)], E-mail: lowrie@lanl.gov; Morel, Jim E. [Department of Nuclear Engineering, Texas A and M University, 3133 TAMU, College Station, TX 77843 (United States)], E-mail: morel@tamu.edu

2009-09-01

203

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

204

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

205

Quasi-free Compton scattering and the polarizabilities of the neutron  

NASA Astrophysics Data System (ADS)

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

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

206

Results from the energetic gamma-ray experiment telescope (EGRET) on the Compton Observatory  

NASA Technical Reports Server (NTRS)

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO) covers the high energy gamma ray energy range, approximately 30 MeV to 30 GeV, with a sensitivity considerably greater than earlier high energy gamma-ray satellites. Thus far, 4 pulsars have been detected and their properties measured, including in 3 cases the energy spectrum as a function of phase. The details of the galactic plane are being mapped and a spectra of the center region has been obtained in good agreement with that expected from cosmic ray interactions. The Magellanic clouds have been examined with the Large Magellanic Cloud (LMC) having been detected at a level consistent with it having a cosmic ray density compatible with quasi-stable equilibrium. Sixteen Active Galactic Nuclei (AGN's) have been seen thus far with a high degree of certainty including 12 quasars and 4 BL Lac objects, but no Seyferts. Time variation has been detected in some of these AGN's

Fichtel, C. E.; Bertsch, D. L.; Dingus, B.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.

1993-01-01

207

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

PubMed

Compton side-scattering has been used to simultaneously downshift the energy of keV to MeV energy range photons while attenuating their flux to enable single-shot, spectrally resolved, measurements of high flux X-ray sources to be undertaken. To demonstrate the technique a 1 mm thick pixelated cadmium telluride detector has been used to measure spectra of Compton side-scattered radiation from a Cobalt-60 laboratory source and a high flux, high peak brilliance X-ray source of betatron radiation from a laser-plasma wakefield accelerator. PMID:24289391

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

2013-11-01

208

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

SciTech Connect

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

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

2013-11-15

209

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

SciTech Connect

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

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

2012-09-15

210

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.

211

Nonrelativistic Compton scattering in Furry's picture. II. Bethe surface by means of the complex-coordinate method  

NASA Astrophysics Data System (ADS)

Bethe surface as a means of characterizing the inelastic scattering of photons and electrons on atomic targets is discussed, and framed within the two-potential Furry's picture of scattering theory. In particular, the cross section for inelastic photon scattering is considered, and its first distorted Born approximation is identified to be given in terms of Bethe surface along the path conserving energy and momentum transfer. The difficulties in obtaining accurate cross sections in situations where the energy transfer is close to the ionization threshold are indicated, and related to the so-called Compton defect. The method for calculating the inelastic photon scattering cross section, introduced in Part I of this work [J. Chem. Phys. 80, 5669 (1984)] is summarized. The scattering cross section, and the entire Bethe surface, is obtained by means of the L2 discretization of the continuum and implemented in terms of the complex-coordinate method, without explicit calculation of the final scattering waves. The method is tested for the case of photon scattering off the hydrogen atom. The results are encouraging, and may be relevant for applications of the complex-coordinate method to calculations of more general transition amplitudes. The method is predicted to be most useful in cases close to ionization threshold (e.g., appearance edges in Compton scattering, Compton defect). Although applied to the one-electron problem the procedure is readily applicable to many electron atoms.

Froelich, Piotr; Flores-Riveros, A.; Weyrich, W.

1985-03-01

212

Gamma ray burst source locations with the Ulysses/Compton/PVO Network. [GB 910814; GB 910522; GB 910717  

SciTech Connect

The new interplanetary gamma-ray burst network will determine source fields with unprecedented accuracy. The baseline of the Ulysses mission and the locations of Pioneer-Venus Orbiter and of Mars Observer will ensure precision to a few tens of arc seconds. Combined with the event phenomenologies of the Burst and Transient Source Experiment on Compton Observatory, the source locations to be achieved with this network may provide a basic new understanding of the puzzle of gamma ray bursts.

Cline, T.L. (NASA/Goddard Space Flight Center, Code 661, Greenbelt, Maryland 20771 (United States)); Hurley, K.C. (University of California, Space Sciences Laboratory, Berkeley, California 94720 (United States)); Boer, M.; Sommer, M. (Max-Planck Institut fur Extraterrestrische Physik, Garching (Germany)); Niel, M. (Centre d'Etude Spatiale des Rayonnements, Toulouse (France)); Fishman, G.J.; Kouveliotou, C.; Meegan, C.A. (NASA/Marshall Space Flight Center, ES-62, Huntsville, Alabama 35812 (United States)); Paciesas, W.S. (NASA/Marshall Space Flight Center, ES-62, Huntsville, Alabama 35812 (United States) Physics Department, University of Alabama, Huntsville, Alabama 358899 (United States)); Wilson, R.B. (NASA/Marshall Space Flight Center, ES-62, Huntsville, Alabama 35812 (United States)); Laros, J.G.; Klebesadel, R.W. (Los Alamos National Laboratory, MS D436, Los Alamos, New Mexico 87545 (United States))

1991-09-01

213

Compton scattering from the proton in an effective field theory with explicit Delta degrees of freedom  

NASA Astrophysics Data System (ADS)

We analyse the proton Compton-scattering differential cross section for photon energies up to 325 MeV using Chiral Effective Field Theory (?EFT) and extract new values for the electric and magnetic polarisabilities of the proton. Our approach builds in the key physics in two different regimes: photon energies ? ? m ? ("low energy"), and the higher energies where the ?(1232) resonance plays a key role. The Compton amplitude is complete at N4LO, {O}( {e^2 ? ^4 } ), in the low-energy region, and at NLO, {O}( {e^2 ? ^0 } ), in the resonance region. Throughout, the Delta-pole graphs are dressed with ? N loops and ?N ? vertex corrections. A statistically consistent database of proton Compton experiments is used to constrain the free parameters in our amplitude: the M1 ?N ? transition strength b 1 (which is fixed in the resonance region) and the polarisabilities ? E1 and ? M1 (which are fixed from data below 170 MeV). In order to obtain a reasonable fit, we find it necessary to add the spin polarisability ? M1 M1 as a free parameter, even though it is, strictly speaking, predicted in ?EFT at the order to which we work. We show that the fit is consistent with the Baldin sum rule, and then use that sum rule to constrain ? E1 + ? M1. In this way we obtain ? E1 = [10.65 ± 0.35(stat) ± 0.2(Baldin) ± 0.3(theory)] × 10-4 fm3 and ? M1 = [3.15 ? 0.35(state) ± 0.2(Baldin) ? 0.3()theory] × 10-4 fm3, with ?2 = 113.2 for 135 degrees of freedom. A detailed rationale for the theoretical uncertainties assigned to this result is provided.

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

2013-01-01

214

Directional Stand-off Detection of Fast Neutrons and Gammas Using Angular Scattering Distributions  

SciTech Connect

We have investigated the response of a DoubleScatter Neutron Spectrometer (DSNS) for sources at long distances (gr than 200 meters). We find that an alternative method for analyzing double scatter data avoids some uncertainties introduced by amplitude measurements in plastic scintillators.Time of flight is used to discriminate between gamma and neutron events, and the kinematic distributions of scattering angles are assumed to apply. Non-relativistic neutrons are most likely to scatter at 45°, while gammas with energies greater than 2 MeV are most likely to be forward scattered. The distribution of scattering angles of fission neutrons arriving from a distant point source generates a 45° cone, which can be back-projected to give the source direction. At the same time, the distribution of Compton-scattered gammas has a maximum in the forward direction, and can be made narrower by selecting events that deposit minimal energy in the first scattering event. We have further determined that the shape of spontaneous fission neutron spectra at ranges gr than 110 m is still significantly different from thecosmic ray background.

Vanier P. e.; Dioszegi, I.; Salwen, C.; Forman, L.

2009-10-25

215

Compton Scattering Focused X-Ray Source for Advanced Biomedical Applications  

NASA Astrophysics Data System (ADS)

The generation of tunable, focused X-ray pulses via ultrahigh intensity Compton backscattering is a subject of considerable importance, with numerous potential applications ranging from biology and medicine to basic research and microchip technology. The practical realization of such a revolutionary light source, however, has been hampered by three serious problems : the lack of ultrahigh intensity sources at optical wavelengths, the absence of focusing optics in the X-ray range, and the nonlinear Doppler shift associated with ultrahigh intensity Compton scattering, which distributes the X-ray energy over many spectral lines. The first issue has now been resolved through the pioneering of laser chirped pulse amplification (CPA). The remaining issues are addressed by two novel ideas : electron beam lensing of the X-rays, and holographic filtering at the Fourier plane of a CPA laser to generate flat-top laser pulses with constant Doppler shift during the interaction. Combined together, these ideas alleviate the major potential problems for the production of focused X-rays.

Chu, T. S.; Hartemann, F. V.; Luhmann, N. C., Jr.

1996-11-01

216

Cross sections of discrete-level excitation of noble-gas atoms in Compton scattering  

NASA Astrophysics Data System (ADS)

The differential cross section in angle and the total cross sections for the excitation of atomic discrete levels in Compton scattering are investigated. Results are presented for the valent np-n,(n+1)d and np-(n+1),(n+2)p levels of the outer subshells of the noble-gas atoms Ne, Ar, Kr, and Xe, covering the range of the momentum transferred to the atom up to 8 a.u., which is sufficiently large for the calculation of the total Compton excitation cross sections. Calculations were performed in one-electron Hartree-Fock approximation and with many-electron effects taken into account in the random-phase approximation with exchange for monopole, dipole, quadrupole, and octupole transitions. Contributions from higher multipoles proved to be unimportant and many-electron effects were found to be quite noticeable in the differential cross section, while almost negligible in the total excitation cross sections. We conclude that the contributions of discrete excitations are comparable to those of the ionization process.

Amusia, M. Ya.; Chernysheva, L. V.; Felfli, Z.; Msezane, A. Z.

2002-06-01

217

The influence of inverse Compton scattering on GRB afterglows: one possible way to flatten and steepen the light curves  

E-print Network

The fireball model of gamma-ray bursts predicted that when the energetic blast wave encountered the surrounding medium, there will be afterglow emission, and the subsequent afterglow observations appeared to confirm this prediction. In this simplest fireball model, the electrons have been accelerated to a power law energy distribution in a relativistic blast wave, then they give afterglow emission through synchrotron radiation. Up to now synchrotron radiation is believed to be the main mechanism of GRB emission, however, here we will show that under some circumstances, the inverse Compton scattering (ICS) may play an important role, and can change the light curves of GRB afterglows. Here we investigate the effects of ICS in the relativistic case (the surrounding medium density $\\rho \\propto r^{-2}$) and in the non-relativistic case (for both $\\rho =constant$ and $\\rho \\propto r^{-2}$), we find that in the relativistic case the effect of ICS is usually important, while in the non-relativistic case, this effect is usually unimportant, unless the surrounding medium density is very high. We show that if ICS is important, then it can flatten and steepen the light curves of GRB afterglows, and this may provide the explanation for some afterglow observations.

D. M. Wei; T. Lu

2000-07-20

218

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

NASA Astrophysics Data System (ADS)

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

Tanaka, Shuta J.; Takahara, Fumio

2013-12-01

219

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

NASA Astrophysics Data System (ADS)

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

Tanaka, Shuta J.; Takahara, Fumio

2013-12-01

220

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

221

Scaling Tests of the Cross Section for Deeply Virtual Compton Scattering  

E-print Network

We present the first measurements of \\vec{e}p->epg cross section in the deep virtual Compton scattering (DVCS) regime and the valence quark region (x_{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^2 = 1.5, 1.9, and 2.3 GeV^2, and the real part of the BH-DVCS interference terms at Q^2 = 2.3 GeV^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^2-variation of the extracted terms -- thereby constraining the size of higher twist contributions to our observables.

Munoz Camacho, C; 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; Gómez, 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; Kelleher, A; Kolarkar, A; Kumbartzki, G; Laveissière, G; Le Rose, 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 V; Potokar, M; Qiang, Y; Ransome, R D; Real, J S; Reitz, B; Roblin, Y; Roche, J; Sabatie, F; Saha, A; Sirca, S; Slifer, K J; Solvignon, P; Subedi, R; Sulkosky, V; Ulmer, P E; Voutier, E; Wang, K; Weinstein, L B; Wojtsekhowski, B; Zheng, X; Zhu, L

2006-01-01

222

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

223

Compton back scatter imaging for mild steel rebar detection and depth characterization embedded in concrete  

NASA Astrophysics Data System (ADS)

A novel non-destructive Compton scattering technique is described to ensure the feasibility, reliability and applicability of detecting the reinforcing steel bar in concrete. The indigenously developed prototype system presented in this paper is capable of detecting the reinforcement of varied diameters embedded in the concrete and as well as up to 60 mm depth, with the aid of Caesium-137(137Cs) radioactive source and a high resolution HPGe detector. The technique could also detect the inhomogeneities present in the test specimen by interpreting the material density variation caused due to the count rate. The experimental results are correlated using established techniques such as radiography and rebar locators. The results obtained from its application to locate the rebars are quite promising and also been successfully used for reinforcement mapping. This method can be applied, especially when the intrusion is located underneath the cover of the concrete or considerably at larger depths and where two sided access is restricted.

Margret, M.; Menaka, M.; Venkatraman, B.; Chandrasekaran, S.

2015-01-01

224

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

225

Laser-Compton Gamma-Ray Source at a Beamline (BL1) in NewSUBARU  

SciTech Connect

We have developed a laser-Compton gamma-ray source at beamline (BL1) in NewSUBARU, an electron storage ring operating at electron energies of 0.7-1.5 GeV. Initially, we generated 17-37 MeV gamma rays using a Nd:YVO{sub 4} laser operating at 1.06 {mu}m and 0.53 {mu}m, achieving a luminosity of 6000 photons/(W{center_dot}mA{center_dot}s) and a flux of 5x10{sup 6} photons/s with a laser power of 4 W and a beam current of 200 mA. We then installed a CO{sub 2} laser operating at 10.6 {mu}m, and generated gamma rays in the energy range of 1-4 MeV. In this range, the gamma-ray luminosity is 7300 photons/(W{center_dot}mA{center_dot}s) and the flux is 5.6x10{sup 6} photons/s when operating the laser at 4 W and 200 mA. These performances are in good agreement with calculations. We will next add a Tm-fiber laser operating at 2 {mu}m to generate gamma rays in the energy range of 4-21 MeV, using a laser-focusing design to generate the maximum flux. The luminosity of this stage is calculated to be 6400 photons/(W{center_dot}mA{center_dot}s). Nd:YVO{sub 4}, CO{sub 2}, and Tm-fiber laser are all capable of operating in a high-power regime and can generate kW-level output power. At present, the maximum gamma-ray flux is limited only by the laser power. When operating the laser at 1 kW of output power with a beam current of 200 mA, we expect a flux of up to {approx}10{sup 9} photons/s. At NewSUBARU, up to several dozen MeV gamma-ray sources are capable of generating such high power.

Amano, Sho; Horikawa, Ken; Miyamoto, Shuji; Mochizuki, Takayasu [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Koto, Kamigori, Ako, Hyogo 678-1205 (Japan)

2010-06-23

226

Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by Mars Observer, Compton Gamma Ray Observatory and Ulysses  

NASA Technical Reports Server (NTRS)

Between 1992 October 4 and 1993 August 1, concurrent coverage by the Compton Gamma Ray Observatory (CGRO), Mars Observer (MO), and Ulysses spacecraft was obtained for 78 gamma-ray bursts (GRBs). Although most of these were below the MO and Ulysses thresholds, nine were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to approximately 2 deg accuracy by the CGRO Burst and Transient Source Experiment (BATSE). We computed arrival-time error boxes with larger dimensions ranging from a few arcminutes to the diameters of the BATSE-only boxes and with smaller dimensions in the arcminute range. Three events are of particular interest: GB 930704 (BATSE 2428) has been described as a possible repeater. The arrival-time information is consistent with that hypothesis, but only just so. The GB 930706 (2431) box, at approximately 1 min x 4 min, is the only one this small obtained since Pioneer Venus Orbiter (PVO) entered the Venusian atmosphere in 1992 October. Sensitive radio and optical observations of this location were made within 8 and 9 days of the burst, but no counterpart candidates were identified. GB 930801 (2477) is the first GRB that had its localization improved by taking into account BATSE Earth occultation.

Laros, J. G.; Boynton, W. V.; Hurley, K.; Kouveliotou, C.; McCollough, M. L.; Fishman, G. J.; Meegan, C. A.

1997-01-01

227

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

228

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

229

The Role of Inverse Compton Scattering in Solar Coronal Hard X-ray and ?-ray Sources  

NASA Astrophysics Data System (ADS)

We consider the role of inverse Compton scattering (ICS) as a means of producing coronal hard X-ray (HXR) and continuum ?-ray sources during solar flares. Coronal HXR and continuum ?-ray emission observed during solar flares has been interpreted in terms of thin-target bremsstrahlung emission. In one case, this interpretation leads to the conclusion that the number of energetic electrons required to account for the coronal HXR source must be large, implying that essentially all electrons in the source must be accelerated to energies ? 16 keV. In other cases, the spectral index of the photon spectrum of ?-ray sources approaches the theoretical limit for bremsstrahlung emission (? ~ 1.5 - 2). Here we investigate ICS in both the fully relativistic and mildly relativistic regimes as an alternative to non-thermal bremsstrahlung. It is known that relativistic electrons are produced during powerful flares; these are capable of up-scattering soft photospheric photons to HXR energies. Previously overlooked is the fact that mildly relativistic electrons, generally produced in much greater numbers in flares of all sizes, can up-scatter EUV/SXR photons to HXR energies. We also explore ICS on anisotropic electron distributions and show that the resulting emission can be significantly enhanced over the case of scattering on an isotropic electron distribution. We apply our results to a selection of coronal HXR and ?-ray events and find that in some cases the ICS mechanism is a viable alternative to non-thermal bremsstrahlung emission, particularly if the energetic population of electrons responsible for the emission is anisotropic.

Chen, B.; Bastian, T. S.

2011-12-01

230

Reionization and cosmic microwave background distortions: a complete treatment of second order Compton scattering  

E-print Network

The ionization history of the universe provides a major source of ambiguity in constraining cosmological models using small angular scale microwave background anisotropies. To clarify these issues, we consider a complete treatment of Compton scattering to second order, an approach which may be applicable to other astrophysical situations. We find that only the ${\\cal O} (v)$ Doppler effect, and the ${\\cal O} (v\\delta)$ Vishniac effect are important for recent last scattering epochs; the ${\\cal O} (v^2)$ Doppler effect is not significant on any angular scale, and other higher-order effects are completely negligible. However the ${\\cal O}(v^2)$ effect does lead to \\Cy\\ distortions, which although generally below current constraints, set an unavoidable minimum level in reionization models. We consider the small-angle approximation for the Vishniac effect in detail, and show several improvements over previous treatments, particularly for low $\\Omega_0$. For standard cold dark matter models, the effect of reionization is to redistribute the anisotropies to arcminute scales; late reionization leads to partially erased primary fluctuations and a secondary contribution of comparable magnitude. Using recent anisotropy limits from the ATCA experiment, we set new constraints on baryonic dark matter models. Stronger constraints are imposed (in second order) upon models with higher Hubble constant, steeper $n$, and higher density. These limits depend on the specific ionization history assumed, but the factor gained by lowering the ionization fraction is generally small, and may be tested by currently-planned

Wayne Hu; Douglas Scott; Joseph Silk

1993-05-29

231

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

232

Radon transforms on generalized Cormack's curves and a new Compton scatter tomography This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Radon transforms on generalized Cormack's curves and a new Compton scatter tomography modality:10.1088/0266-5611/27/12/125001 Radon transforms on generalized Cormack's curves and a new Compton/125001 Abstract In his seminal work of 1981, Cormack established that Radon transforms defined on two remarkable

Nguyen-Verger, Maï K.

233

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

234

Compton scattering and charge transfer in Er substituted DyAl2  

NASA Astrophysics Data System (ADS)

A unique applicability of Compton spectroscopy in probing the electronic states of rare earth aluminides using high energy (662 keV) ?-rays is reported. We have measured first-ever Compton profiles of Dy1-xErxAl2 (x=0, 0.2) using 20Ci 137Cs Compton spectrometer. The charge reorganization in Dy1-xErxAl2 (x=0, 0.2), on the formation of compound, has been discussed using the valence band Compton profile data. The experimental Compton profile data unambiguously establish charge transfer from Al to Dy (Dy and Er) on formation of x=0.0 (0.2) compound, which is in tune with spin polarized relativistic Korringa-Kohn-Rostoker (SPR-KKR) calculations. A reasonable agreement between SPR-KKR based Compton profiles and the experimental data show applicability of the Green function method in predicting the electronic properties of rare earth compounds.

Ahuja, B. L.; Mohammad, F. M.; Mohammed, S. F.; Sahariya, Jagrati; Mund, H. S.; Heda, N. L.

2015-02-01

235

Inversion of a new circular-arc Radon transform for Compton scattering tomography This article has been downloaded from IOPscience. Please scroll down to see the full text article.  

E-print Network

Inversion of a new circular-arc Radon transform for Compton scattering tomography This article has:10.1088/0266-5611/26/6/065005 Inversion of a new circular-arc Radon transform for Compton scattering-arc Radon transform arising from the mathematical modeling of image formation in a new modality of Compton

Nguyen-Verger, Maï K.

236

Collective Spectra of the Resonant Inverse Compton Scattering of the Assembly of Relativistic Electrons in an Intense Magnetic Field  

NASA Astrophysics Data System (ADS)

The resonant inverse Compton scattering (RICS) of relativistic electrons in an intense magnetic field of a neutron star is an efficient mechanism for producing the high-energy ?-rays due to its high efficiency, high frequency, highly beaming behaviour and comparatively good monochromaticity, concentrating most radiation in the high-frequency band (hard X-ray and ?-ray). In our previous work, it is argued that the dominant radiation mechanism responsible for the prompt ?-ray emission of gamma-ray bursts (GRBs) in the early stage could be the RICS of relativistic electrons. By using this mechanism, some puzzles in the study of GRBs could be clarified, e.g., the origin of the Amati relation, the formation of the observed broken power-law spectra, the related deadline problem, the polarization property, etc. The simplified analytical formulae of collective RICS spectra of the assembly of relativistic electrons in an intense magnetic field are derived in this paper, based on the simple RICS power spectra of a single fast electron given in our previous work. By using these formulae, a series of collective RICS spectra for various typical ambient low-frequency radiation fields around the central neutron star, e.g., the black body radiation, the nonthermal field with a power-law spectrum and the thermal bremsstrahlung field, are calculated. The collective RICS spectra are all in quite simple analytical expressions, which are convenient for comparison with the observed spectra. Our calculations show that the RICS process is really a very efficient radiation mechanism in the hard X-ray and ?-ray bands if the "accommodation condition" (or the "matching condition") is satisfied. Our calculations show that despite what kind of ambient soft-photon field is related, various collective RICS spectra have common broken power-law forms with different indexes in the low- and high-frequency bands respectively. Finally, we discuss the potential applications of RICS mechanism in high-energy astrophysics, i.e., in the explorations of the origins of radiation from GRBs, soft gamma-ray repeaters (SGRs) and gamma-ray pulsars (GRPs), etc.

Liu, D. B.; Huang, Y. F.; Danzeng, L. B.; Chen, T. L.

2011-01-01

237

The detector response matrices of the burst and transient source experiment (BATSE) on the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

The detector response matrices for the Burst And Transient Source Experiment (BATSE) on board the Compton Gamma Ray Observatory (CGRO) are described, including their creation and operation in data analysis. These response matrices are a detailed abstract representation of the gamma-ray detectors' operating characteristics that are needed for data analysis. They are constructed from an extensive set of calibration data coupled with a complex geometry electromagnetic cascade Monte Carlo simulation code. The calibration tests and simulation algorithm optimization are described. The characteristics of the BATSE detectors in the spacecraft environment are also described.

Pendleton, Geoffrey N.; Paciesas, William S.; Mallozzi, Robert S.; Koshut, Tom M.; Fishman, Gerald J.; Meegan, Charles A.; Wilson, Robert B.; Horack, John M.; Lestrade, John Patrick

1995-01-01

238

Electronic structure of CdMoO{sub 4} using Compton scattering technique  

SciTech Connect

The first ever Compton profile of polycrystalline CdMoO{sub 4} has been measured using {sup 137}Cs spectrometer. The results are compared with theoretical Compton profiles deduced from free atom and linear combination of atomic orbitals (LCAO) methods. We have also computed the energy bands using density functional theory (DFT) within LCAO. The computed bands confirm the semiconducting behaviour of this compound. It is seen that the DFT theoretical profile (with local density approximation) gives a better agreement with the experimental Compton data than free atom Compton profile.

Sharma, Khushboo, E-mail: khushboo.phy@gmail.com; Ahuja, B. L. [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur-313001 (India); Sahariya, Jagrati [Department of Physics, Manipal University, Jaipur-303007 (India)

2014-04-24

239

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

E-print Network

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

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

2012-06-28

240

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

SciTech Connect

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

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

2012-07-01

241

Evaluation of Compton gamma camera prototype based on pixelated CdTe detectors.  

PubMed

A proposed Compton camera prototype based on pixelated CdTe is simulated and evaluated in order to establish its feasibility and expected performance in real laboratory tests. The system is based on module units containing a 2×4 array of square CdTe detectors of 10×10 mm(2) area and 2 mm thickness. The detectors are pixelated and stacked forming a 3D detector with voxel sizes of 2 × 1 × 2 mm(3). The camera performance is simulated with Geant4-based Architecture for Medicine-Oriented Simulations(GAMOS) and the Origin Ensemble(OE) algorithm is used for the image reconstruction. The simulation shows that the camera can operate with up to 10(4) Bq source activities with equal efficiency and is completely saturated at 10(9) Bq. The efficiency of the system is evaluated using a simulated (18) F point source phantom in the center of the Field-of-View (FOV) achieving an intrinsic efficiency of 0.4 counts per second per kilobecquerel. The spatial resolution measured from the point spread function (PSF) shows a FWHM of 1.5 mm along the direction perpendicular to the scatterer, making it possible to distinguish two points at 3 mm separation with a peak-to-valley ratio of 8. PMID:24932209

Calderón, Y; Chmeissani, M; Kolstein, M; De Lorenzo, G

2014-06-01

242

High efficiency x-ray source based on inverse Compton scattering in an optical Bragg structure  

NASA Astrophysics Data System (ADS)

Existing x-ray sources based on inverse Compton scattering rely on free-space lasers and have modest efficiency due to the inherent limitation of maintaining their peak field intensity over a few Rayleigh lengths. Moreover, their typical interaction spots are tens of micrometres in diameter and they rely on large electron accelerators. We propose a new structure that mitigates many of these limiting factors by confining the interaction in an optical Bragg waveguide, specially designed to support a TEM mode within its sub-micrometre hollow core. This allows the e-beam-laser interaction to be as long as the waveguide itself, resulting in superior spectral quality of the emerging x-ray. Furthermore, the regular RF accelerator may be replaced by an optical Bragg accelerator. This two-stage design, from acceleration to x-ray emission, is expected to have a table-top size, and it is estimated to provide x-ray brightness of 3 × 1017 (photons s-1 mm-2 mrad-2/0.1%BW), while utilizing laser power several orders of magnitude smaller than comparable free-space sources.

Karagodsky, Vadim; Schächter, Levi

2011-01-01

243

Development of a 4-mirror optical cavity for an inverse Compton scattering experiment in the STF  

NASA Astrophysics Data System (ADS)

To obtain high-brightness quasi-monochromatic X-rays via inverse Compton scattering (ICS), an optical cavity for intensifying laser beams was designed and implemented in a new beam line at the KEK Superconducting RF Test Facility (STF) accelerator. The optical cavity adopts a planar configuration consisting of 4 mirrors. This confocal type resonator provides stable laser storage even with a long mirror distance, enabling head-on collision with the electron beams. To overcome the well-known astigmatism problems of the planar-type optical cavity, two forcibly bendable cylindrical mirrors were introduced instead of flat mirrors. With this new function for laser profile adjustment, an almost round laser profile at the waist point in the accelerator environment was successfully achieved. Estimated waist sizes were 43.7 ?m for the horizontal and 50.8 ?m for the vertical dimensions. The feedback control of this 4-mirror optical cavity worked with a stiff plate supporting all 4 mirrors. 1.7×103 finesse and 2.8-kW stored power for a 1-ms duration with 5 Hz were achieved.

Shimizu, Hirotaka; Aryshev, Alexander; Higashi, Yasuo; Honda, Yosuke; Urakawa, Junji

2014-05-01

244

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

245

X-ray generation by inverse Compton scattering at the superconducting RF test facility  

NASA Astrophysics Data System (ADS)

Quasi-monochromatic X-rays with high brightness have a broad range of applications in fields such as life sciences, bio-, medical applications, and microlithography. One method for generating such X-rays is via inverse Compton scattering (ICS). X-ray generation experiments using ICS were carried out at the superconducting RF test facility (STF) accelerator at KEK. A new beam line, newly developed four-mirror optical cavity system, and new X-ray detector system were prepared for experiments downstream section of the STF electron accelerator. Amplified pulsed photons were accumulated into a four-mirror optical cavity and collided with an incoming 40 MeV electron beam. The generated X-rays were detected using a microchannel plate (MCP) detector for X-ray yield measurements and a new silicon-on-insulator (SOI) detector system for energy measurements. The detected X-ray yield by the MCP detector was 1756.8±272.2 photons/(244 electron bunches). To extrapolate this result to 1 ms train length under 5 Hz operations, 4.60×105 photons/1%-bandwidth were obtained. The peak X-ray energy, which was confirmed by the SOI detector, was 29 keV, and this is consistent with ICS X-rays.

Shimizu, Hirotaka; Akemoto, Mitsuo; Arai, Yasuo; Araki, Sakae; Aryshev, Alexander; Fukuda, Masafumi; Fukuda, Shigeki; Haba, Junji; Hara, Kazufumi; Hayano, Hitoshi; Higashi, Yasuo; Honda, Yosuke; Honma, Teruya; Kako, Eiji; Kojima, Yuji; Kondo, Yoshinari; Lekomtsev, Konstantin; Matsumoto, Toshihiro; Michizono, Shinichiro; Miyoshi, Toshinobu; Nakai, Hirotaka; Nakajima, Hiromitsu; Nakanishi, Kota; Noguchi, Shuichi; Okugi, Toshiyuki; Sato, Masato; Shevelev, Mikhail; Shishido, Toshio; Takenaka, Tateru; Tsuchiya, Kiyosumi; Urakawa, Junji; Watanabe, Ken; Yamaguchi, Seiya; Yamamoto, Akira; Yamamoto, Yasuchika; Sakaue, Kazuyuki; Hosoda, Seiichi; Iijima, Hokuto; Kuriki, Masao; Tanaka, Ryuta; Kuramoto, Ayaka; Omet, Mathieu; Takeda, Ayaki

2015-02-01

246

Driver linac design for a femtosecond head-on inverse Compton scatteringX-ray source  

NASA Astrophysics Data System (ADS)

The feasibility of generating an ultra-short relativistic electron beam with a thermionic cathode rf gun driver linac for a femtosecond head-on inverse Compton scattering (ICS) X-ray source has been examined by space charge tracking throughout the entire beamline, from the cathode to the interaction point. It has been determined that GHz-repetition-rate electron pulses as short as 49 fs can be produced by compressing the energy-chirped beam from a 2998-MHz, 1.5-cell rf gun with an alpha magnet and an rf linac operating at the injection phase near the zero crossing. These electron pulses, with a 42-pC bunch charge, are accelerated to 27 MeV with an S-band traveling-wave constant-gradient linac structure for the ICS in an interaction chamber located downstream. The driver linac design that allows the operation of an ultra-short ICS X-ray source at a 0.7-Å wavelength, with a peak photon flux of 9.08×1017 photons/s, is presented in this paper.

Huang, N. Y.; Lau, W. K.; Liang, C. C.; Lee, A. P.; Cheng, W. C.; Yang, S. S.

2011-05-01

247

Inverse Compton scattering of coherent synchrotron radiation in an energy recovery linac  

NASA Astrophysics Data System (ADS)

We propose inverse Compton scattering (ICS) of coherent synchrotron radiation (CSR) from a relativistic short electron bunch in energy recovery linacs (ERL) as a high-flux subpicosecond x-ray and ?-ray source. An advantage of the CSR scheme over a conventional ICS source is that no external laser is required, and synchronization between CSR pulses and electron bunches is obtained automatically. Moreover, higher-flux x rays can be generated from the ICS of CSR in an ERL operated at a high repetition rate, 100 MHz to 1.3 GHz. Using parameters of the Compact ERL at KEK, 1×1013-14phs/s b.w. 10% (the number of photons pulse-1 bandwidth unit-1) x ray with a 100 fs-1 ps pulse duration can be obtained, for an energy range from 0.04 to 4 keV. In the case of a 5-GeV ERL, ? rays with energy around tens of MeV are generated with 1×108phs/pulse b.w. 10% at a repetition rate of several hundreds of MHz.

Shimada, M.; Hajima, R.

2010-10-01

248

Nonstationary Radiative Transfer: Evolution of a Spectrum by Multiple Compton Scattering  

NASA Astrophysics Data System (ADS)

A new method is used for numerical solution of the nonlinear integro-differential radiative transfer equation for the evolution of a homogeneous emission spectrum owing to Compton scattering on equilibrium free electrons in an infinite uniform space. The temperature of the electron gas is assumed constant with no limits placed on it: the electrons can be both nonrelativistic and relativistic. The evolution of the spectrum is found to depend substantially on the initial dimensionless photon density. There is a bounday value for this density such that at lower values, there is a limiting equilibrium Bose-Einstein photon distribution, but not at higher values. In the latter case a quasi-line develops which shifts to shorter wavelengths with time while its width decreases and its maximum intensity increases. Calculations are carried out using two frequency redistribution functions of the photons, exact and simplified (assuming an isotropic distribution in the laboratory coordinate system). The results are compared with solutions of the Kompaneets equation.

Grachev, S. I.

2014-12-01

249

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. PMID:21508442

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

2011-01-01

250

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

251

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

2011-05-21

252

The effective attenuation coefficient of soft tissue in the presence of Compton scattering from bone: experiments on models.  

PubMed

Calibration methods are investigated for the determination of bone density by the Compton scattering method. The scattered radiation from materials of different densities and dimensions is measured for this purpose. A function for the dependence of the intensity on these parameters is derived and compared with the experimental results. The influence of the surrounding soft tissue is studied by simulation experiments with water. It is found that the 'effective attenuation coefficient' of water for the incident and scattered radiation depends on the thickness of the surrounding water layer itself, as well as on the density of the scattering material. The implications of these findings for the evaluation of bone density measurements are discussed. PMID:7454760

Leichter, I; Weinreb, A; Hazan, G

1980-07-01

253

Magnetic Properties of Co2MnO4 using Magnetic Compton Scattering  

NASA Astrophysics Data System (ADS)

Spin momentum density of Co2MnO4 has been measured at 10 K using magnetic Compton spectrometer at SPring-8, Japan. Magnetic Compton profile has also been analyzed to determine the spin moment at different sites of the constituent atoms. It is observed that the Co 3d electrons are coupled antiferromagnetically with Mn 3d electrons. The total magnetic moment of Co2MnO4 is dominated by Mn 3d site. The Compton profile based spin moment at 10 K when compared with the magnetization data (using vibrating sample magnetometer) shows small contribution of orbital moment (0.06±0.02?B).

Ahuja, B. L.; Dashora, Alpa; Heda, N. L.; Tiwari, Shailja; Kumar, Ravi; Itou, M.; Sakurai, Y.

2011-06-01

254

Frequency scaling law for nonlinear Compton and Thomson scattering: Relevance of spin and polarization effects  

NASA Astrophysics Data System (ADS)

The distributions of Compton and Thomson radiation for a shaped laser pulse colliding with a free electron are calculated in the framework of quantum and classical electrodynamics, respectively. We introduce a scaling law for the Compton and the Thomson frequency distributions which universally applies to long and short incident pulses. Thus, we extend the validity of frequency scaling postulated in previous studies comparing nonlinear Compton and Thomson processes. The scaling law introduced in this paper relates the Compton no-spin flipping process to the Thomson process over nearly the entire spectrum of emitted radiation, including its high-energy portion. By applying the frequency scaling, we identify that both spin and polarization effects are responsible for differences between classical and quantum results. The same frequency scaling applies to angular distributions and to temporal power distributions of emitted radiation, which we illustrate numerically.

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

2014-11-01

255

Frequency scaling law for nonlinear Compton and Thomson scattering: Relevance of spin and polarization effects  

E-print Network

The distributions of Compton and Thomson radiation for a shaped laser pulse colliding with a free electron are calculated in the framework of quantum and classical electrodynamics, respectively. We introduce a scaling law for the Compton and the Thomson frequency distributions which universally applies to long and short incident pulses. Thus, we extend the validity of frequency scaling postulated in previous studies comparing nonlinear Compton and Thomson processes. The scaling law introduced in this paper relates the Compton no-spin flipping process to the Thomson process over nearly the entire spectrum of emitted radiation, including its high-energy portion. By applying the frequency scaling, we identify that both spin and polarization effects are responsible for differences between classical and quantum results. The same frequency scaling applies to angular distributions and to temporal power distributions of emitted radiation, which we illustrate numerically.

K. Krajewska; J. Z. Kaminski

2014-11-09

256

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

257

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

NASA Technical Reports Server (NTRS)

The Arthur Holly Compton Gamma Ray Observatory (GRO) was launched by the shuttle Atlantis in April 1991. This paper presents the results of the attitude sensor calibration that was performed during the early mission. The GSFC Flight Dynamics Facility (FDF) performed an alignment calibration of the two fixed-head star trackers (FHST's) and two fine Sun sensors (FSS's) on board Compton GRO. The results show a 27-arcsecond shift between the bore sights of the FHST's with respect to prelaunch measurements. The alignments of the two FSS's shifted by 0.20 and 0.05 degree. During the same time period, the Compton GRO science teams performed an alignment calibration of the science instruments with respect to the attitude reported by the on board computer (OBC). In order to preserve these science alignments, FDF adjusted the overall alignments of the FHST's and FSS's, obtained by the FDF calibration, such that when up linked to the OBC, the shift in the OBC-determined attitude is minimized. FDF also calibrated the inertial reference unit (IRU), which consists of three dual-axis gyroscopes. The observed gyro bias matched the bias that was solved for by the OBC. This bias drifted during the first 6 days after release. The results of the FDF calibration of scale factor and alignment shifts showed changes that were of the same order as their uncertainties.

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

1993-01-01

258

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

259

Gamma-ray burst spectra and spectral correlations from sub-photospheric Comptonization  

E-print Network

One of the most important unresolved issues in gamma-ray burst physics is the origin of the prompt gamma-ray spectrum. Its general non-thermal character and the softness in the X-ray band remain unexplained. We tackle these issues by performing Monte Carlo simulations of radiation-matter interactions in a scattering dominated photon-lepton plasma. The plasma -- initially in equilibrium -- is driven to non-equilibrium conditions by a sudden energy injection in the lepton population, mimicking the effect of a shock wave or the dissipation of magnetic energy. Equilibrium restoration occurs due to energy exchange between the photons and leptons. While the initial and final equilibrium spectra are thermal, the transitional photon spectra are characterized by non-thermal features such as power-law tails, high energy bumps, and multiple components. Such non-thermal features are observed at infinity if the dissipation occurs at small to moderate optical depths, and the spectrum is released before thermalization is co...

Chhotray, Atul

2015-01-01

260

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

SciTech Connect

We have made the first measurements of the virtual Compton scattering (VCS) process via the H(e,e'p)? exclusive reaction in the nucleon resonance region, at backward angles. Results are presented for the W-dependence at fixed Q2=1 GeV2, and for the Q2-dependence at fixed W near 1.5 GeV. The VCS data show resonant structures in the first and second resonance regions. The observed Q2-dependence is smooth. The measured ratio of H(e,e'p)? to H(e,e'p)?0 cross sections emphasizes the different sensitivity of these two reactions to the various nucleon resonances. Finally, when compared to Real Compton Scattering (RCS) at high energy and large angles, our VCS data at the highest W (1.8-1.9 GeV) show a striking Q2-independence, which may suggest a transition to a perturbative scattering mechanism at the quark level.

Laveissiere, Geraud; Degrande, Natalie; Jaminion, Stephanie; Jutier, Christophe; Todor, Luminita; Di Salvo, Rachele; Van Hoorebeke, L.; Alexa, L.C.; Anderson, Brian; Aniol, Konrad; Arundell, Kathleen; Audit, Gerard; Auerbach, Leonard; Baker, F.; Baylac, Maud; Berthot, J.; Bertin, Pierre; Bertozzi, William; Bimbot, Louis; Boeglin, Werner; Brash, Edward; Breton, Vincent; Breuer, Herbert; Burtin, Etienne; Calarco, John; Cardman, Lawrence; Cavata, Christian; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chen, Jian-Ping; Chudakov, Eugene; Cisbani, Evaristo; Dale, Daniel; De Jager, Cornelis; De Leo, Raffaele; Deur, Alexandre; D'Hose, Nicole; Dodge, Gail; Domingo, John; Elouadrhiri, Latifa; Epstein, Martin; Ewell, Lars; Finn, John; Fissum, Kevin; Fonvieille, Helene; Fournier, Guy; Frois, Bernard; Frullani, Salvatore; Furget, Christophe; Gao, Haiyan; Gao, Juncai; Garibaldi, Franco; Gasparian, Ashot; Gilad, Shalev; Gilman, Ronald; Glamazdin, Oleksandr; Glashausser, Charles; Gomez, Javier; Gorbenko, Viktor; Grenier, Philippe; Guichon, Pierre; Hansen, Jens-Ole; Holmes, Richard; Holtrop, Maurik; Howell, Calvin; Huber, Garth; Hyde, Charles; Incerti, Sebastien; Iodice, Mauro; Jardillier, Johann; Jones, Mark; Kahl, William; Kamalov, Sabit; Kato, Seigo; Katramatou, A.T.; Kelly, James; Kerhoas, Sophie; Ketikyan, Armen; Khayat, Mohammad; Kino, Kouichi; Kox, Serge; Kramer, Laird; Kumar, Krishna; Kumbartzki, Gerfried; Kuss, Michael; Leone, Antonio; LeRose, John; Liang, Meihua; Lindgren, Richard; Liyanage, Nilanga; Lolos, George; Lourie, Robert; Madey, Richard; Maeda, Kazushige; Malov, Sergey; Manley, D.; Marchand, Claude; Marchand, Dominique; Margaziotis, Demetrius; Markowitz, Pete; Marroncle, Jacques; Martino, Jacques; McCormick, Kathy; McIntyre, Justin; Mehrabyan, Surik; Merchez, Fernand; Meziani, Zein-Eddine; Michaels, Robert; Miller, Gerald; Mougey, Jean; Nanda, Sirish; Neyret, Damien; Offermann, Edmond; Papandreou, Zisis; Perdrisat, Charles; Perrino, R.; Petratos, Gerassimos; Platchkov, Stephane; Pomatsalyuk, Roman; Prout, David; Punjabi, Vina; Pussieux, Thierry; Quemener, Gilles; Ransome, Ronald; Ravel, Oliver; Real, Jean-Sebastien; Renard, F.; Roblin, Yves; Rowntree, David; Rutledge, Gary; Rutt, Paul; Saha, Arunava; Saito, Teijiro; Sarty, Adam; Serdarevic, A.; Smith, T.; Smirnov, G.; Soldi, K.; Sorokin, Pavel; Souder, Paul; Suleiman, Riad; Templon, Jeffrey; Terasawa, Tatsuo; Tiator, Lothar; Tieulent, Raphael; Tomasi-Gustaffson, E.; Tsubota, Hiroaki; Ueno, Hiroaki; Ulmer, Paul; Urciuoli, Guido; Van De Vyver, R.; van der Meer, Rob; Vernin, Pascal; Vlahovic, B.; Voskanyan, Hakob; Voutier, Eric; Watson, J.W.; Weinstein, Lawrence; Wijesooriya, Krishni; Wilson, R.; Wojtsekhowski, Bogdan; Zainea, Dan; Zhang, Wei-Ming; Zhao, Jie; Zhou, Z.-L.

2009-01-01

261

Gamma-ray burst observations with the [ital Compton]/[ital Ulysses]/[ital Pioneer]-[ital Venus] network  

SciTech Connect

The third and latest interplanetary network for the precise directional analysis of gamma ray bursts consists of the Burst and Transient Source Experiment in [ital Compton] [ital Gamma] [ital Ray] [ital Observatory] and instruments on [ital Pioneer]-[ital Venus] [ital Orbiter] and the deep-space mission [ital Ulysses]. The unsurpassed resolution of the BATSE instrument, the use of refined analysis techniques, and [ital Ulysses]' distance of up to 6 AU all contribute to a potential for greater precision than had been achieved with former networks. Also, the departure of [ital Ulysses] from the ecliptic plane in 1992 avoids any positional alignment of the three instruments that would lessen the source directional accuracy.

Cline, T.L. (NASA/Goddard Space Flight Center, Code 661, Greenbelt, Maryland 20771 (United States)); Hurley, K.C. (University of California, Space Sciences Laboratory, Berkeley, California 94720 (United States)); Sommer, M. (Max-Planck Institut fuer Extraterrestrische Physik, Garching (Germany)); Boer, M.; Niel, M. (Centre d'Etude Spatiale des Rayonnements, Toulouse (France)); Fishman, G.J.; Kouveliotou, C.; Meegan, C.A.; Paciesas, W.S.; Wilson, R.B. (NASA/Marshall Space Flight Center, ES-62, Huntsville, Alabama 35812 (United States)); Fenimore, E.E.; Laros, J.G.; Klebesadel, R.W. (Los Alamos National Laboratory, MS D436, Los Alamos, New Mexico 87545 (United States))

1993-07-05

262

THE {gamma}-RAY SPECTRUM OF GEMINGA AND THE INVERSE COMPTON MODEL OF PULSAR HIGH-ENERGY EMISSION  

SciTech Connect

We reanalyze the Fermi spectra of the Geminga and Vela pulsars. We find that the spectrum of Geminga above the break is well approximated by a simple power law without the exponential cutoff, making Geminga's spectrum similar to that of Crab. Vela's broadband {gamma}-ray spectrum is equally well fit with both the exponential cutoff and the double power-law shapes. In the broadband double power-law fits, for a typical Fermi spectrum of a bright {gamma}-ray pulsar, most of the errors accumulate due to the arbitrary parameterization of the spectral roll-off. In addition, a power law with an exponential cutoff gives an acceptable fit for the underlying double power-law spectrum for a very broad range of parameters, making such fitting procedures insensitive to the underlying Fermi photon spectrum. Our results have important implications for the mechanism of pulsar high-energy emission. A number of observed properties of {gamma}-ray pulsars-i.e., the broken power-law spectra without exponential cutoffs and stretching in the case of Crab beyond the maximal curvature limit, spectral breaks close to or exceeding the maximal breaks due to curvature emission, patterns of the relative intensities of the leading and trailing pulses in the Crab repeated in the X-ray and {gamma}-ray regions, presence of profile peaks at lower energies aligned with {gamma}-ray peaks-all point to the inverse Compton origin of the high-energy emission from majority of pulsars.

Lyutikov, Maxim [Department of Physics, Purdue University, 525 Northwestern Avenue, West Lafayette, IN 47907-2036 (United States)

2012-09-20

263

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 5×10 13 gammas/s with the latest laser and accelerator technologies.

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

2010-09-01

264

Determination of the mass attenuation coefficients for X-ray fluorescence measurements correction by the Rayleigh to Compton scattering ratio  

NASA Astrophysics Data System (ADS)

X-ray fluorescence technique plays an important role in nondestructive analysis nowadays. The development of equipment, including portable ones, enables a wide assortment of possibilities for analysis of stable elements, even in trace concentrations. Nevertheless, despite of the advantages, one important drawback is radiation self-attenuation in the sample being measured, which needs to be considered in the calculation for the proper determination of elemental concentration. The mass attenuation coefficient can be determined by transmission measurement, but, in this case, the sample must be in slab shape geometry and demands two different setups and measurements. The Rayleigh to Compton scattering ratio, determined from the X-ray fluorescence spectrum, provides a link to the mass attenuation coefficient by means of a polynomial type equation. This work presents a way to construct a Rayleigh to Compton scattering ratio versus mass attenuation coefficient curve by using the MCNP5 Monte Carlo computer code. The comparison between the calculated and literature values of the mass attenuation coefficient for some known samples showed to be within 15%. This calculation procedure is available on-line at www.macx.net.br.

Conti, C. C.; Anjos, M. J.; Salgado, C. M.

2014-09-01

265

Electron density of Rhizophora spp. wood using Compton scattering technique at 15.77, 17.48 and 22.16 keV XRF energies  

NASA Astrophysics Data System (ADS)

Compton (incoherently) scattered photons which are directly proportional to the electron density of the scatterer, have been employed in characterizing Rhizophora spp. as breast tissue equivalent. X-ray fluorescent scattered incoherently from Rhizophora spp. sample was measured using Si-PIN detector and three XRF energy values 15.77, 17.48 and 22.16 keV. This study is aimed at providing electron density information in support of the introduction of new tissue substitute materials for mammography phantoms.

Shakhreet, B. Z.; Bauk, S.; Shukri, A.

2015-02-01

266

Forward Compton Scattering with weak neutral current: constraints from sum rules  

E-print Network

We generalize forward real Compton amplitude to the case of the interference of the electromagnetic and weak neutral current, formulate a low-energy theorem, relate the new amplitudes to the interference structure functions and obtain a new set of sum rules. We address a possible new sum rule that relates the product of the axial charge and magnetic moment of the nucleon to the 0th moment of the structure function $g_5(\

Gorchtein, Mikhail

2015-01-01

267

Electronic properties of RDX and HMX: Compton scattering experiment and first-principles calculation.  

PubMed

The first-ever electron momentum density (EMD) measurements of explosive materials, namely, RDX (1,3,5-trinitro-1,3,5-triazacyclohexane, (CH2-N-NO2)3) and HMX (1,3,5,7-tetranitro-1,3,5,7-tetraazacyclooctane, (CH2-N-NO2)4), have been reported using a 740 GBq (137)Cs Compton spectrometer. Experimental Compton profiles (CPs) are compared with the EMDs derived from linear combination of atomic orbitals with density functional theory. It is found that the CPs deduced from generalized gradient approximation (GGA) with Wu-Cohen exchange energies give a better agreement with the corresponding experimental profiles than those from local density approximation and other schemes of GGA. Further, Mulliken population, energy bands, partial and total density of states, and band gap have also been reported using GGA calculations. Present ground state calculations unambiguously show large band gap semiconductor nature of both RDX and HMX. A similar type of bonding in these materials is uniquely established using Compton data and density of states. It is also outstandingly consistent with the Mulliken population, which predicts almost equal amount of charge transfer (0.84 and 0.83 e(-)) from H1 + H2 + N2 to C1 + N1 + O1 + O2 in both the explosives. PMID:23763382

Ahuja, B L; Jain, Pradeep; Sahariya, Jagrati; Heda, N L; Soni, Pramod

2013-07-11

268

Inverse Compton conversion. Final report  

SciTech Connect

Inverse Compton conversion has been proposed as an alternative to the bremsstrahlung conversion process as a method of transforming the kinetic energy of an electron beam into a directed beam of photons. An electron beam with incident electron kinetic energy E{sub o} enters a volume of dimension L containing a photon gas, which is characterized by a blackbody temperature E{sub bb} and a density {rho}{sub {gamma}}. The electrons will inverse-Compton scatter with individual photons in the photon gas. In this process, energy is transferred to the photons, which are then emitted in the forward direction. The resultant photon beam could be used to deliver a radiation dose to a distant target. This report discusses the theoretical formulation of the problem, presents sample results, and describes the computer code developed to analyze this concept.

Weitz, R.L. [Science Applications International Corp., Albuquerque, NM (United States)

1990-11-19

269

Neutron Compton scattering investigation of sodium hydride: From bulk material to encapsulated nanoparticulates in amorphous silica gel  

NASA Astrophysics Data System (ADS)

In this study we utilize neutron Compton scattering (NCS) to determine differences in nuclear momentum distributions in NaH, both as bulk material and encapsulated as nanoscale particles (from 20 to 50 nm in diameter) within an amorphous silica-gel matrix (SiGNaH). In addition, elemental Na dispersed in such a matrix is also studied (SiGNa). Data treatment and fitting of experimental spectra yields comparison of the nuclear Compton profiles and radial momentum distributions for the proton in both bulk NaH and nanoscale SiGNaH, with resultant proton kinetic energies being in agreement with previous inelastic neutron studies of bulk NaH. Slight differences in proton radial momentum distributions for bulk and nanoscale systems are witnessed and discussed. The technique of stoichiometric-fixing is applied to the backscattering spectra of each system in order to examine changes in the Na profile width, and NCS is shown to be sensitive to the chemical environment change of this heavier nucleus. Examination of the Si and O profile widths in the gel samples also supports this method.

Seel, A. G.; Sartbaeva, A.; Mayers, J.; Ramirez-Cuesta, A. J.; Edwards, P. P.

2011-03-01

270

Compton profile of polycrystalline tungsten  

SciTech Connect

In this paper we report the experimental Compton profile of polycrystalline tungsten. The measurements have been made by scattering 59.54-keV ..gamma.. rays and are compared with the band-structure calculation of Papanicolaou et al. These results have also been compared with our calculation based on the renormalized-free-atom model with different 5d-6s configurations. Best agreement with experiment is found for the 5d/sup 5.4/6s/sup 0.6/ electron configuration.

Mittal, U.; Sharma, B.K.; Mohammad, F.M.; Ahuja, B.L.

1988-12-15

271

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

NASA Astrophysics Data System (ADS)

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 volume resolution in thick structures has previously been achieved only by fixed laboratory installations involving massive primary beam shields (collimators) between source and detectors. Here the design of a relatively portable collimator (98 kg mass) for a cobalt 60 source is given. It permits three dimensional material density imaging, with voxel (3-dimensional pixel) volumes small enough to permit the detection of voids down to 10 cubic mm in up to 30 mm thickness of steel or 250 mm of wood (for example, a 500 mm diameter tree trunk). Using a 370 GBq source, typical results of thickness measurements to a precision of 1 mm over cross sections down to 10 square mm are presented. The collimator mass is reducible to about 68 kg with the use of depleted uranium instead of lead. The means of deploying such a collimator in a mobile way are discussed. A typical in-situ application is the detection of inner wall corrosion and flooding of tubular members of underwater offshore oil platforms and ship hulls without the need to remove hard marine growth. Another case is the detection of telegraph pole and tree rot below ground level.

Bridge, B.

2000-05-01

272

Development and Assessment of Compton Scattered X-Ray Technique for Bone Density Measurement In-Vivo  

NASA Astrophysics Data System (ADS)

A Compton Scatter X-ray Bone Densitometer for Bone Density determination in-vivo is described. The system uses a single 90 kVp quasi-continuous X-ray source and three scintillation crystal detectors--two CsI(Na) scintillators for low flux scattered beam and one plastic scintillator for high flux transmission beam. Each density determination involves four intensity measurements using digital electronics --two of transmitted beams and two of compton scattered radiation. Theoretical studies are made on the contribution from multiple scattering phenomenon which limits the precise determination of density. Preliminary studies have been made on beam hardening effects which arise due to the polychromatic nature of X-ray photon beam. A number of spectra for transmitted and scattered X-ray beams have been taken under various configurations to make some qualitative assessment of the complexity of the problem involved. The main emphasis has been on the compromise between the radiation dose to the limited area of the human subject under investigation and the statistical precision of density measurement. In -vitro measurements on non-biological samples have been made to assess the accuracy and precision of the system before performing in-vivo studies on subjects. A series of normal volunteer human subjects selected at random from among the Carleton University community has been studied to collect density data for normals. The site chosen for density measurement was in the tibia of right leg of the subject. Using linear regression, measurements were normalized to 40 yrs age & 70 kg wt for male subjects and 40 yrs age & 60 kg wt for female subjects. It is found that the bone density values thus obtained had a mean of 1.35 g/cm('3) with FWHM of 0.20 g/cm('3) for males and 0.35 g/cm('3) for females. The frequency distribution of density values showed they were skewed towards higher density from mean value and peaked at 1.48 g/cm('3) both for male and female subjects. In-vivo density measurements on human subjects were obtained with a standard deviation of the order of (+OR-) 1.5 % from counting statistics with exposure dose to the localized region under study of about 200 mR. Repositioning of bone site under study reduces the precision to about (+OR-) 5 %.

Kapoor, Kulvir Kumar

273

Microscopic magnetic properties of an oxygen-doped Tb-Fe thin film by magnetic Compton scattering  

SciTech Connect

The magnetic Compton scattering of a Tb{sub 32}Fe{sub 55}O{sub 13} film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect the magnetization process of the magnetic moments of Tb and Fe.

Agui, Akane, E-mail: agui@spring8.or.jp [Quantum Beam Science Directorate, Japan Atomic Energy Agency, SPring-8, Sayo, Hyogo 679-5148 (Japan); Unno, Tomoya; Matsumoto, Sayaka; Suzuki, Kousuke; Sakurai, Hiroshi [Department of Production Science and Technology, Gunma University, Ota, Gunma 373-0057 (Japan); Koizumi, Akihisa [Graduate School of Material Science, University of Hyogo, Kamigori, Hyogo 678-1297 (Japan)

2013-11-14

274

Guiding of X-rays from Inverse Compton Scattering as a means to enhance flux and brightness  

NASA Astrophysics Data System (ADS)

Guiding of the X-ray photons emitted in an Inverse Compton Scattering (ICS) device is possible using small diameter tubes. Whereas guiding of the electron and laser beams can directly increase the flux output of ICS interactions, manipulating the beams' propagation can be very challenging. Guiding the output X-rays can be straightforward and offers three enhancements of the usable flux: off-axis X-rays are collimated along the tube; out of bandwidth photons are not guided and therefore filtered out; and, the guiding can be extended far from the interaction region towards the intended application. A tube, acting as a waveguide for the X-rays, can increase the brightness relative to free space propagation by the square of the number of reflections. We present preliminary calculations of the guiding mechanism and explain why Liouville's theorem is not violated. Typical achievable parameters and application scenarios are also described including practically realizable waveguides and materials.

Travish, G.; Gover, A.; Pellegrini, C.; Rosenzweig, J. B.

2009-09-01

275

Microscopic magnetic properties of an oxygen-doped Tb-Fe thin film by magnetic Compton scattering  

NASA Astrophysics Data System (ADS)

The magnetic Compton scattering of a Tb32Fe55O13 film was measured in order to investigate the microscopic magnetization processes (i.e., the spin moment, orbital moment, and element specific moments). The trend of the spin magnetic moment was the same as that of the total magnetic moment but opposite to the orbital magnetic moment. In the low magnetic field region, the magnetic moments were not perfectly aligned perpendicular to the film surface, and the perpendicular components were found to mainly arise from the magnetic moment of Tb. Oxygen atoms hinder long range magnetic interaction and hence also affect the magnetization process of the magnetic moments of Tb and Fe.

Agui, Akane; Unno, Tomoya; Matsumoto, Sayaka; Suzuki, Kousuke; Koizumi, Akihisa; Sakurai, Hiroshi

2013-11-01

276

Advances on Ultrafast Silicon Field Emitter Array Photocathodes for Coherent Radiation Sources Based on Inverse Compton Scattering  

NASA Astrophysics Data System (ADS)

Low-cost, compact, and coherent X-rays sources would enable exciting applications such as biomedical imaging of soft tissue and real-time visualisation of molecules at a widespread scale. A promising approach to implement such an X-ray source is based on inverse Compton scattering of a series of nanostructured electron sheets accelerated to relativistic speeds. Photon-triggered field emission arrays can readily produce planar arrays of electron bunches with pC-level sheet charge at high repetition rates using intense laser pulses. In this article, the performance of single-crystal, ultrafast, photon-actuated silicon field emitter arrays is investigated for varying emitter height. Charge vs. incident photon pulse energy characteristics and quantum efficiency of the devices are reported.

Dong, C.; Swanwick, M.; Keathley, P. D.; Kärtner, F. X.; Velásquez-García, L. F.

2014-11-01

277

High-energy gamma-ray beams from Compton-backscattered laser light  

SciTech Connect

Collisions of light photons with relativistic electrons have previously been used to produce polarized ..gamma..-ray beams with modest (-10%) resolution but relatively low intensity. In contrast, the LEGS project (Laser + Electron Gamma Source) at Brookhaven will produce a very high flux (>2 x 10/sup 7/ s/sup -1/) of background-free polarized ..gamma.. rays whose energy will be determined to a high accuracy (..delta..E = 2.3 MeV). Initially, 300(420)-MeV ..gamma.. rays will be produced by backscattering uv light from the new 2.5(3.0)-GeV X-ray storage ring of the National Synchrotron Light Source (NSLS). The LEGS facility will operate as one of many passive users of the NSLS. In a later stage of the project, a Free Electron Laser is expectred to extend the ..gamma..-ray energy up to 700 MeV.

Sandorfi, A.M.; LeVine, M.J.; Thorn, C.E.; Giordano, G.; Matone, G.

1983-01-01

278

Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz  

NASA Astrophysics Data System (ADS)

A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standing-wave linac and rf photoinjector powered by a single ultrastable rf transmitter at X-band rf frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. The entire accelerator is approximately 1 meter long and produces hard x rays tunable over a wide range of photon energies. The colliding laser is a Yb ?YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for many passes in a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is 5 ×1 011 photons /second in a 5% bandwidth and the brilliance is 2 ×1 012 photons /(sec mm2 mrad2 0.1 %) in pulses with rms pulse length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic energy, 10 microamp average current, 0.5 microsecond macropulse length, resulting in average electron beam power of 180 W. Optimization of the x-ray output is presented along with design of the accelerator, laser, and x-ray optic components that are specific to the particular characteristics of the Compton scattered x-ray pulses.

Graves, W. S.; Bessuille, J.; Brown, P.; Carbajo, S.; Dolgashev, V.; Hong, K.-H.; Ihloff, E.; Khaykovich, B.; Lin, H.; Murari, K.; Nanni, E. A.; Resta, G.; Tantawi, S.; Zapata, L. E.; Kärtner, F. X.; Moncton, D. E.

2014-12-01

279

The Quantum Mechanics of Nano-Confined Water: New Cooperative Effects Revealed with Neutron and X-Ray Compton Scattering  

NASA Astrophysics Data System (ADS)

Neutron Compton scattering(NCS) measurements of the momentum distribution of light ions using the Vesuvio instrument at ISIS provide a sensitive local probe of the environment of those ions. NCS measurements of the proton momentum distribution in bulk water show only small deviations from the usual picture of water as a collection of molecules, with the protons covalently bonded to an oxygen and interacting weakly, primarily electrostatically, with nearby molecules. However, a series of measurements of the proton momentum distribution in carbon nanotubes, xerogel, and Nafion show that the proton delocalizes over distances of 0.2-0.3Å when water is confined on the scale of 20Å. This delocalization must be the result of changes in the Born-Oppenheimer surface for the protons, which would imply that there are large deviations in the electron distribution from that of a collection of weakly interacting molecules. This has been observed at Spring-8 using x-ray Compton scattering. The observed deviation in the valence electron momentum distribution from that of bulk water is more than an order of magnitude larger than the change observed in bulk water as the water is heated from just above melting to just below boiling. We conclude that the protons and electrons in nano-confined water are in a qualitatively different ground state from that of bulk water. Since the properties of this state persist at room temperature, and the confinement distance necessary to observe it is comparable to the distance between the elements of biological cells, this state presumably plays a role in the functioning of those cells.

Reiter, G. F.; Deb, Aniruddha

2014-12-01

280

Analysis of Data from the Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

The final report consists of summaries of work proposed, work accomplished, papers and presentations published and continuing work regarding the cooperative agreement. The work under the agreement is based on high energy gamma ray source data analysis collected from the Energetic Gamma-Ray Experiment Telescope (EGRET).

Kniffen, Donald A.; Elliott, William W.

1999-01-01

281

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

NASA Technical Reports Server (NTRS)

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 listed in the Third EGRET Catalog and were included in determining the detection likelihood, flux, and spectra of those sources. In particular, five detected EGRET pulsars are found to have events above 10 GeV, and together they account for 37 events. A pulsar not included in the Third EGRET Catalog has 2 events, both with the same phase and in one peak of the lower-energy gamma-ray light-curve. Most of the remaining 1319 events appear to be diffuse Galactic and extragalactic radiation based on the similarity of the their spatial and energy distributions with the diffuse model and in the E>100, MeV emission. No significant time clustering which would suggest a burst was detected.

Thompson, D. J.; Bertsch, D. L.; ONeal, R. H., Jr.

2005-01-01

282

Few arc-minute and keV resolutions with the TIGRE Compton telescope  

NASA Technical Reports Server (NTRS)

The tracking and imaging gamma ray experiment (TIGRE) Compton telescope concept can provide an angular resolution of a few arcmin, an energy resolution of a few keV and high sensitivity, while providing the wide field of view necessary for surveying and monitoring observations. Silicon and CdZnTe strip detectors are used to detect Compton pair events and determine their incident directions and energies. Above 400 keV, Compton recoil electrons are tracked through successive layers of thin silicon strip detectors. Compton scattered photons are detected with CdZnTe strip detectors. Pair electrons and positrons are tracked to provide high sensitivity observations in the 10 to 100 MeV range. Polarization studies are performed with large angle Compton scatter events. The TIGRE concept and development status are described.

Zych, A.; Bhattacharya, D.; Dixon, D.; ONeill, T.; Tuemer, T.; White, R. S.; Ryan, J.; McConnell, M.; Macri, J.; Oegelman, H.; Paulos, R.; Wheaton, W.; Akyuez, A.; Samimi, J.; Oezel, M.

1997-01-01

283

Nonrelativistic Compton scattering in Furry's picture: Beyond the sudden impulse approximation by means of the complex coordinate method  

NASA Astrophysics Data System (ADS)

Basic electrodynamical and collision theory presumptions related to Compton scattering are critically reconsidered (with particular emphasis on identifying the proper transition matrix element effectively controlling the process, and on framing it within time dependent perturbation theory and scattering theory) in order to indicate the main features and the validity of the proposed method. The on-energy-shell transition matrix element governing the cross-sectional formula is obtained from Furry's two-potential formalism, which makes possible a treatment of the primary electron-photon interaction to first order while incorporating the effects of the final state Coulombic interaction to all orders. Furry's procedure, in addition to defining clearly which initial and final states should enter the transition matrix element, also brings additional insight into the nature of the so-called ``sudden impulse approximation.'' A treatment is proposed in which the decisive transition matrix element is obtained without explicit calculation of the distorted continuum solutions implied by Furry's procedure, but is instead extracted from the dispersion relations of the ``beat-frequency'' dependent generalized polarizability by means of the L2 treatment based on the complex-coordinate method. The practical advantage of the method will be its ability to incorporate correlation between the ejected electron and the electrons remaining in the ion.

Froelich, P.; Weyrich, Wolf

1984-06-01

284

Proton momentum distribution and anomalous scattering intensities in a pseudo-spherical ammonium ion: a neutron Compton scattering study of (NH(4))(2)PdCl(6) and (NH(4))(2)TeCl(6).  

PubMed

Neutron Compton scattering (NCS) measurements on ammonium hexachloropalladate and hexachlorotellurate were performed at room temperature. Proton scattering intensities and momentum distributions, as measured in the NCS experiment, have been compared with results expected from the impulse approximation (IA) for both systems. The measurement shows that scattering intensity from protons is anomalous even though their momentum distribution has a second moment that agrees very well with the ab initio calculation for an isolated pseudo-spherical NH(4)(+) ion in the ground vibrational state. Detailed data analysis shows that there is no extra (beyond the IA expected value) broadening or peak shift of proton momentum distribution due to ultra-fast kinetics of the Compton scattering process leading to anomalous scattering intensities. This is most probably due to highly symmetric local potential in the NH(4)(+). Presented results have interesting implications for further theoretical work in the field. PMID:21817329

Krzystyniak, M; Lalowicz, Z T; Chatzidimitriou-Dreismann, C A; Lerch, M

2009-02-18

285

Synchrotron-Self Compton XRay and gamma Ray Variability in Relativistic Jets  

Microsoft Academic Search

All of the extragalactic objects so far detected in high energy gamma -rays (>50 MeV) by the EGRET instrument aboard CGRO are highly variable radio loud sources having compact core emission. These properties are thought to result from nonthermal radiation in a compact relativistic jet which is occassionally enhanced by propagating shock waves. At some level, the electrons which produce

John P. Travis; Alan P. Marscher

1993-01-01

286

The development of a Compton lung densitometer  

SciTech Connect

A field instrument is being developed for the non-invasive determination of absolute lung density using unique Compton backscattering techniques. A system consisting of a monoenergetic gamma-ray beam and a shielded high resolution high-purity-germanium (HPGe) detector in a close-coupled geometry is designed to minimize errors due to multiple scattering and uncontrollable attenuation in the chestwall. Results of studies on system performance with phantoms, the optimization of detectors, and the fabrication of a practical gamma-ray source are presented. 3 refs., 6 figs., 2 tabs.

Loo, B.W.; Goulding, F.S.; Madden, N.W.; Simon, D.S.

1988-11-01

287

Gamma ray astrophysics. [emphasizing processes and absorption  

NASA Technical Reports Server (NTRS)

Gamma ray production processes are reviewed, including Compton scattering, synchrotron radiation, bremsstrahlung interactions, meson decay, nucleon-antinucleon annihilations, and pion production. Gamma ray absorption mechanisms through interactions with radiation and with matter are discussed, along with redshifts and gamma ray fluxes.

Stecker, F. W.

1974-01-01

288

Compton Profile Study of Intermetallic Ti{sub 3}Al  

SciTech Connect

The Compton scattering measurement on intermetallic alloy Ti{sub 3}Al is reported in this work. The measurement is made using 59.54 keV gamma-rays from Am{sup 241} source. Theoretical calculation of Compton profile is also performed employing CRYSTAL code within the framework of density functional theory to compare with the measurement. The theoretical profile of the alloy is also synthesized following the superposition model taking the published Compton profiles of elemental solids from the APW method. The experimental study of charge transfer in the alloys has also been done by performing the experimental Compton profile measurements on Ti and Al following the superposition model and charge transfer from Al to Ti is clearly seen on the alloy formation.

Vyas, V.; Sharma, G. [Department of Physics, Banasthali University, Banasthali-304022 (India); Mishra, M. C.; Sharma, B. K. [Department of Physics, University of Rajasthan, Jaipur-302004 (India); Joshi, K. B. [Department of Physics, University College of Science, M.L.Sukhadia University, Udaipur-313 002 (India)

2011-10-20

289

Neutron Compton scattering as a molecular characterization technique: A study on NaHF{sub 2}  

SciTech Connect

Inelastic neutron scattering experiments were performed at intermediate and high momentum transfers, up to 85-90 A ring {sup -1}, to study the proton momentum distribution in polycrystalline sodium hydrogen fluoride (NaHF{sub 2}) at low temperature (below 5 K). The H mean kinetic energy was extracted and compared to the results from hydrogen-projected density of phonon states derived from intermediate momentum transfer inelastic neutron scattering and lattice dynamics simulations. A reasonable agreement between the two figures was found. In addition, relevant aspects of high momentum transfer neutron scattering from NaHF{sub 2} were explored in detail, ranging from an alternative evaluation of final state effects to the role played by the instrumental resolution and to the possibility to reconstruct the potential felt by a proton from its momentum distribution.

Colognesi, D. [Istituto dei Sistemi Complessi, Consiglio Nazionale delle Ricerche, Sezione di Firenze, via Madonna del Piano 10, 50019 Sesto Fiorentino, Florence (Italy); Pietropaolo, A.; Senesi, R. [Dipartimento di Fisica and Centro NAST, Universita degli Studi di Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Rome (Italy); Ramirez-Cuesta, A. J. [ISIS Facility, Rutherford Appleton Laboratory, Chilton, Didcot, Oxon OX11 0QX (United Kingdom)

2007-11-01

290

Design of a 4.8-m ring for inverse Compton scattering x-ray source  

NASA Astrophysics Data System (ADS)

In this paper we present the design of a 50 MeV compact electron storage ring with 4.8-meter circumference for the Tsinghua Thomson scattering x-ray source. The ring consists of four dipole magnets with properly adjusted bending radii and edge angles for both horizontal and vertical focusing, and a pair of quadrupole magnets used to adjust the horizontal damping partition number. We find that the dynamic aperture of compact storage rings depends essentially on the intrinsic nonlinearity of the dipole magnets with small bending radius. Hamiltonian dynamics is found to agree well with results from numerical particle tracking. We develop a self-consistent method to estimate the equilibrium beam parameters in the presence of the intrabeam scattering, synchrotron radiation damping, quantum excitation, and residual gas scattering. We also optimize the rf parameters for achieving a maximum x-ray flux.

Xu, H. S.; Huang, W. H.; Tang, C. X.; Lee, S. Y.

2014-07-01

291

Head-On Inverse Compton Scattering X-rays with Energy beyond 10 keV from Laser-Accelerated Quasi-Monoenergetic Electron Bunches  

NASA Astrophysics Data System (ADS)

Inverse Compton X-rays from laser-accelerated multiple electron bunches are observed. A Ti:sapphire laser (pulse energy: 500 mJ; pulse width: 150 fs) beam is divided into two beams. The main beam is focused onto an edge of a helium gas jet to accelerate electrons to energies of 14 and 23 MeV, which inversely scattered the head-on colliding secondary laser beam into 6 and 12 keV X-rays; this agrees well with that calculated from the electron spectra obtained. This demonstrates a first on-axis inverse Compton scattering X-ray energy detection beyond 10 keV induced by laser-accelerated electrons.

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

2012-05-01

292

Non-Linear Compton Scattering of Ultrashort and Ultraintense Laser Pulses  

E-print Network

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

D. Seipt; B. Kampfer

2010-10-16

293

Evaluation of list-mode ordered subset expectation maximization image reconstruction for pixelated solid-state compton gamma camera with large number of channels  

NASA Astrophysics Data System (ADS)

The Voxel Imaging PET (VIP) Pathfinder project intends to show the advantages of using pixelated solid-state technology for nuclear medicine applications. It proposes designs for Positron Emission Tomography (PET), Positron Emission Mammography (PEM) and Compton gamma camera detectors with a large number of signal channels (of the order of 106). For Compton camera, especially with a large number of readout channels, image reconstruction presents a big challenge. In this work, results are presented for the List-Mode Ordered Subset Expectation Maximization (LM-OSEM) image reconstruction algorithm on simulated data with the VIP Compton camera design. For the simulation, all realistic contributions to the spatial resolution are taken into account, including the Doppler broadening effect. The results show that even with a straightforward implementation of LM-OSEM, good images can be obtained for the proposed Compton camera design. Results are shown for various phantoms, including extended sources and with a distance between the field of view and the first detector plane equal to 100 mm which corresponds to a realistic nuclear medicine environment.

Kolstein, M.; De Lorenzo, G.; Chmeissani, M.

2014-04-01

294

Nondestructive assay of plutonium and minor actinide in spent fuel using nuclear resonance fluorescence with laser Compton scattering ?-rays  

NASA Astrophysics Data System (ADS)

We propose a new nondestructive assay method for 235U, 239Pu, and minor actinides in spent nuclear fuel assembly in a water pool. Nuclear fuel materials are detected using nuclear resonance fluorescence (NRF) with laser Compton scattering (LCS) ?-rays. The NRF assay can provide a finger print of each isotope since the NRF ?-ray energy is characteristic of a specific nuclide. We design a high-flux LCS ?-ray source, in which ?-rays are generated by collision of laser photons provided from Yb-doped fiber laser and electrons from energy recovery linac. This system has following advantages; this can detect isotopes of most elements behind heavy materials such as uranium of a thickness of several centimeters, and analyze the fuel assembly in a water pool. A simulation calculation shows that we can detect 1% fraction 239Pu in all the fuel rods with statistical error lower than 2% using the high flux LCS ?-ray source and the measurement time of 4000 s.

Hayakawa, Takehito; Kikuzawa, Nobuhiro; Hajima, Ryoichi; Shizuma, Toshiyuki; Nishimori, Nobuyuki; Fujiwara, Mamoru; Seya, Michio

2010-09-01

295

Inhomogeneities in type Ib/c supernovae: An inverse Compton scattering origin of the X-ray emission  

E-print Network

Inhomogeneities in a synchrotron source can severely affect the conclusions drawn from observations regarding the source properties. However, their presence is not always easy to establish, since several other effects can give rise to similar observed characteristics. It is argued that the recently observed broadening of the radio spectra and/or light curves in some of the type Ib/c supernovae is a direct indication of inhomogeneities. As compared to a homogeneous source, this increases the deduced velocity of the forward shock and the observed correlation between total energy and shock velocity could in part be due to a varying covering factor. The X-ray emission from at least some type Ib/c supernovae is unlikely to be synchrotron radiation from an electron distribution accelerated in a non-linear shock. Instead it is shown that the observed correlation during the first few hundred days between the radio, X-ray and bolometric luminosities indicates that the X-ray emission is inverse Compton scattering of th...

Bjornsson, C -I

2013-01-01

296

INHOMOGENEITIES IN TYPE Ib/c SUPERNOVAE: AN INVERSE COMPTON SCATTERING ORIGIN OF THE X-RAY EMISSION  

SciTech Connect

Inhomogeneities in a synchrotron source can severely affect the conclusions drawn from observations regarding the source properties. However, their presence is not always easy to establish, since several other effects can give rise to similar observed characteristics. It is argued that the recently observed broadening of the radio spectra and/or light curves in some Type Ib/c supernovae is a direct indication of inhomogeneities. As compared to a homogeneous source, this increases the deduced velocity of the forward shock and the observed correlation between total energy and shock velocity could in part be due to a varying covering factor. The X-ray emission from at least some Type Ib/c supernovae is unlikely to be synchrotron radiation from an electron distribution accelerated in a nonlinear shock. Instead it is shown that the observed correlation during the first few hundred days between the radio, X-ray, and bolometric luminosities indicates that the X-ray emission is inverse Compton scattering of the photospheric photons. Inhomogeneities are consistent with equipartition between electrons and magnetic fields in the optically thin synchrotron emitting regions.

Bjoernsson, C.-I., E-mail: bjornsson@astro.su.se [Department of Astronomy, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden)

2013-05-20

297

The Compton Observatory in perspective  

Microsoft Academic Search

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 15 keV to 30 GeV, with sensitivity over the entire range and order of magnitude better than

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

1993-01-01

298

A global test of factorization for nucleon-nucleon, gamma p and gamma gamma scattering  

Microsoft Academic Search

The purpose of this note is to show that the cross section factorization relation $\\\\sigma_{nn}(s)\\/\\\\sigma_{\\\\gamma p}(s) = \\\\sigma_{\\\\gamma p}(s)\\/ \\\\sigma_{\\\\gamma\\\\gamma}(s)$ is satisfied experimentally in the energy domain $8\\\\le\\\\sqrt s\\\\le 2000$ GeV, where the $\\\\sigma$'s are total cross sections and $nn$ denotes the even portion of the $pp$ and $\\\\pbar p$ total cross section. A convenient phenomenological paramaterization for a global

Martin M. Block; K. Kang

2003-01-01

299

Detection of high-energy gamma-ray emission from the BL Lacertae object Markarian 421 by the Egret telescope on the Compton Observatory  

NASA Technical Reports Server (NTRS)

Gamma radiation in the energy range from 50 MeV to well over 1 GeV has been observed from the direction of the BL Lac object Markarian 421 by the Energetic Gamma Ray Experiment Telescope on the Compton Observatory during the period 1991 June 27-July 11. The source flux is weak, but still statistically significant at the level of 10 exp -5; the integrated photon flux above 100 MeV is (1.4 +/- 0.3) x 10 exp -7/sq cm s. The differential photon energy spectrum can be represented by a power law with exponent 1.96 +/- 0.14. This is the first detection of gamma-ray emission from a BL Lac object.

Lin, Y. C.; Bertsch, D. L.; Chiang, J.; Fichtel, C. E.; Hartman, R. C.; Hunter, S. D.; Kanbach, G.; Kniffen, D. A.; Kwok, P. W.; Mattox, J. R.

1992-01-01

300

A global test of factorization for nucleon-nucleon, gamma p and gamma gamma scattering  

E-print Network

The purpose of this note is to show that the cross section factorization relation $\\sigma_{nn}(s)/\\sigma_{\\gamma p}(s) = \\sigma_{\\gamma p}(s)/ \\sigma_{\\gamma\\gamma}(s)$ is satisfied experimentally in the energy domain $8\\le\\sqrt s\\le 2000$ GeV, where the $\\sigma$'s are total cross sections and $nn$ denotes the even portion of the $pp$ and $\\pbar p$ total cross section. A convenient phenomenological paramaterization for a global simultaneous fit to the $pp$, $\\pbar p$, $\\gamma p$ and $\\gamma\\gamma$ total cross section data together with the $\\rho$-value data for $pp$ and $\\pbar p$ is provided by using real analytic amplitudes. Within experimental errors, we show that factorization is satisfied when we unfold the published $\\gamma\\gamma$ data which had averaged the cross sections obtained by using the two different PHOJET and PYTHIA Monte Carlo results. Our analysis clearly favors the PHOJET results and suggests that the additive quark model, together with vector meson dominance, allows one to compute $\\sigma_{\\gamma p}(s)$ and $\\sigma_{\\gamma\\gamma}(s)$ from $\\sigma_{nn}(s)$ with essentially no free parameters. The universal $\\rho$-value predicted by our fit, {\\em i.e.,} $\\rho_{nn} = \\rho_{\\gamma p} = \\rho_{\\gamma\\gamma}$, is compared to the $\\rho$-value obtained by a QCD-inspired analysis of $\\pbar p$ and $pp$ data, including the p-air cross sections from cosmic rays. The $\\rho$-values obtained from the two techniques are essentially indistinguishable in the energy region $8\\le\\sqrt s\\le 2000$ GeV, giving us increased confidence in our parameterization of the cross sections needed for the factorization relation.

M. M. Block; K. Kang

2004-03-02

301

JOURNAL DE PHYSIQUE CoZZoque C7, supptdment a u n07, Tome 40, JuiZZet 1979, page C7-853 RAYLnGH AND COMPTON XATTEFUNGCROSS SECTIOUS OF X-RAYS BY OXYGENIONS  

E-print Network

scattering are widely used in plasma diagnostic [I) .The X-rays and gamma rays attenuation and energy cross sections for X-rays absorption at energies above 1 keV can be written as the sum of all partial cross sections for the photoelec- tric effect, for Rayleigh and Compton scattering. X-rays and gamma

Boyer, Edmond

302

The role of 3d electrons in the appearance of ferromagnetism in the antiferromagnetic Ru2MnGe Heusler compound: a magnetic Compton scattering study.  

PubMed

The antiferromagnetism in Ru(2)MnGe can be suppressed by the substitution of V by Mn and ferromagnetism appears. Synchrotron-based magnetic Compton scattering experiments are used in order to investigates the role of 3d electrons in the indirect/direct exchange interactions for the appearance of ferromagnetism. A small spin moment for the itinerant electron part on the magnetic Compton profile indicates that the metallic ferromagnet Ru(2)Mn(0.5)V(0.5)Ge has a weak indirect exchange interaction between the d-like and sp-like (itinerant) electrons. This suggests that the appearance of ferromagnetism is caused by the enhancement of the direct exchange interactions between d-d electrons in the Ru(2)MnGe Heusler compound. These findings indicate that the indirect exchange interaction between itinerant electrons and localized electrons is a significant key point for the appearance of ferromagnetism in this system. PMID:22634608

Mizusaki, S; Ohnishi, T; Douzono, A; Hirose, M; Nagata, Y; Itou, M; Sakurai, Y; Ozawa, T C; Samata, H; Noro, Y

2012-06-27

303

METHOD FOR MEASURING DENSITY AND THICKNESS OF OBJECT BY $gamma$RAY SCATTERING  

Microsoft Academic Search

Experiments concerned with sensitive and exact measurements of the ; density and thickness of an object, reducing such disadvantages as usually occur ; in the ordinary scattering method, are reported. The essentials of the ; experiments are that gamma rays emitting from the source are collimated, ; directed, and scattered into the object undergoing measurement, and thus ; scattered gamma

I. Tajiri; M. Shimada; M. Mitsutsuka; M. Yamate

1963-01-01

304

Detection of a long-duration solar gamma-ray flare on Jun. 11, 1991 with EGRET on Compton-GRO  

NASA Technical Reports Server (NTRS)

On 11 Jun. 1991, the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (Comption-GRO) observed high energy gamma radiation above 30 MeV from the Sun following an intense flare around 2:00 Universal Time (UT). After the decay of most of the x ray flare, which caused nearly complete deadtime losses in EGRET, high energy emission was registered during the interval from about 3:30 UT to at least 10:30 UT. Gamma rays were detected up to energies above 1 GeV. The solar origin of the emission is assured by the time profile of the gamma ray count rate and by time resolved sky maps, which show a clear maximum at the position of the sun. The gamma ray lightcurve of the flare can be described with two components: a fast decaying emission with an e-folding time constant of about 25 minutes and a slow decay with about 255 minutes. There are indications for a spectral evolution with time, such that the emission below 100 MeV fades away earlier than the 100 to 300 MeV radiation, roughly in the time scale of the fast component. The spectrum of the flare can be fitted with a composite of a proton generated pion neutral spectrum and an electron bremsstrahlung component. The latter can be identified with the fast decaying component of the lightcurve.

Kanbach, G.; Bertsch, D. L.; Fitchel, C. E.; Hartman, R. C.; Hunter, S. D.; Kniffen, D. A.; Kwok, P. W.; Lin, Y. C.; Mattox, J. R.; Mayer-Hasslewander, H. A.

1992-01-01

305

Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering at Q2=0.92 and 1.76 Gev2: II. Dispersion Relation Analysis  

SciTech Connect

Virtual Compton Scattering is studied at the Thomas Jefferson National Accelerator Facility in the energy domain below pion threshold and in the Delta(1232) resonance region. The data analysis is based on the Dispersion Relation (DR) approach. The electric and magnetic Generalized Polarizabilities (GPs) of the proton and the structure functions Pll-Ptt/epsilon and Plt are determined at four-momentum transfer squared Q2=0.92 and 1.76 GeV2. The DR analysis is consistent with the low-energy expansion analysis. The world data set indicates that neither the electric nor magnetic GP follows a simple dipole form.

Geraud Laveissiere; Luminita Todor; Natalie Degrande; Stephanie Jaminion; Christophe Jutier; Rachele Di Salvo; L. Van Hoorebeke; et al

2003-12-01

306

Magnetic properties of NiFe2-xRExO4 (RE=Dy, Gd) using magnetic Compton scattering  

NASA Astrophysics Data System (ADS)

Temperature dependent spin momentum densities of NiFe2-xRExO4 (x=0, 0.05; RE=Dy, Gd) ferrites have been measured using a magnetic Compton spectrometer available at SPring-8, Japan. The experimental profiles of NiFe2O4 (NFO) with doping of Dy and Gd show almost similar spin moment as of undoped NFO. The contribution of different constituents in the formation of total spin moment is also deduced from the analysis of Compton line shape. It is seen that 5% doping of Dy3+ or Gd3+ ions at Fe3+ sites leads to a redistribution of spin moment at Fe3+ and RE3+ sites. The magnetic Compton data when compared with the magnetization data (using a vibrating sample magnetometer) show almost a constant orbital moment (0.21±0.03 µB/f.u.) in the doped and undoped NFO.

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

2014-06-01

307

A Simple Comptonization Model  

NASA Astrophysics Data System (ADS)

We present an empirical model of Comptonization for fitting the spectra of X-ray binaries. This model, named simpl, has been developed as a package implemented in XSPEC. With only two free parameters, simpl is competitive as the simplest model of Compton scattering. Unlike the pervasive standard power-law model, simpl incorporates the basic features of Compton scattering of soft photons by energetic coronal electrons. Using a simulated spectrum, we demonstrate that simpl closely matches the behavior of physical Comptonization models that consider the effects of optical depth, coronal electron temperature, and geometry. We present fits to RXTE spectra of the black hole transient H1743-322 and a BeppoSAX spectrum of LMC X-3 using both simpl and the standard power-law model. A comparison of the results shows that simpl gives equally good fits, while eliminating the troublesome divergence of the standard power-law model at low energies. simpl is completely flexible and can be used self-consistently with any seed spectrum of photons. We show an example of how simpl-unlike the standard power law-teamed up with diskbb (the standard model of disk accretion) provides a uniform disk normalization that is unaffected by moderate Comptonization.

Steiner, James F.; Narayan, Ramesh; McClintock, Jeffrey E.; Ebisawa, Ken

2009-11-01

308

Fast neutron scattering cross sections for terbium-159 via the (n,n'gamma) and (n,n') techniques  

NASA Astrophysics Data System (ADS)

Scattering cross sections for fast neutrons were measured for low-lying levels of 159Tb, a deformed odd-A nucleus. Levels from 400 keV up to 1000 keV in excitation were studied by the (n,n'?) technique, while elastic and inelastic scattering for the lower lying excited states were studied via the (n,n') technique. For the (n,n'?) experiment, a Ge detector was used in conjunction with the pulsed beam time-of-flight technique to observe de-excitation gamma decays. A NaI(Tl) annulus was used to suppress signals caused by Compton scattered gamma rays. Gamma-ray production cross sections were measured in the 400- to 1000-keV incident neutron energy range in 50-keV intervals at a scattering angle of 125°. Thirty six gamma-ray transitions from 16 levels of 159.Tb were observed and placed in the decay scheme. Neutron level cross sections were inferred from the differential gamma- ray production cross sections. Neutron elastic and inelastic scattering angular distributions for this nuclide were measured via the time-of-flight technique at incident neutron energies of 575 keV and 995 keV. The neutron detector consisted of a plastic scintillator mounted on a fast photomultiplier tube. Measurements were made at 11 angles from 35° to 135° in 10-degree steps for 995 keV and at 5 angles for 575 keV. Neutrons were produced in a thin lithium target using the 7Li(p,n)7Be reaction with protons generated by the University of Massachusetts Lowell Van de Graaff Accelerator. Level cross section results using the (n,n'?) technique are compared with the those using the (n,n') technique for lower-lying levels, 241 keV(9/2+), a three-level cluster of 348 keV(5/2+), 363 keV(5/2-), and 388 keV(7/2-), and 428 keV(7/2+) states. The results are also compared with previous work and to the ENDF/B-VI, JEF-2, and JENDL-3 evaluations.

Seo, Pil-Neyo

2001-08-01

309

Helium Compton Form Factor Measurements at CLAS  

SciTech Connect

The distribution of the parton content of nuclei, as encoded via the generalized parton distributions (GPDs), can be accessed via the deeply virtual Compton scattering (DVCS) process contributing to the cross section for leptoproduction of real photons. Similarly to the scattering of light by a material, DVCS provides information about the dynamics and the spatial structure of hadrons. The sensitivity of this process to the lepton beam polarization allows to single-out the DVCS amplitude in terms of Compton form factors that contain GPDs information. The beam spin asymmetry of the $^4$He($\\vec {\\mathrm e}$,e$' \\gamma ^4$He) process was measured in the experimental Hall B of the Jefferson Laboratory to extract the real and imaginary parts of the twist-2 Compton form factor of the $^4$He nucleus. The experimental results reported here demonstrate the relevance of this method for such a goal, and suggest the dominance of the Bethe-Heitler amplitude to the unpolarized process in the kinematic range explored by the experiment.

Voutier, Eric J.-M. [Laboratoire de Physique Subatomique et Cosmologie

2013-07-01

310

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

PubMed

A three-dimensional (3D) point-kernel multiple scatter model for point spread function (PSF) determination in parallel-beam single-photon emission computed tomography (SPECT), based on a dose gamma-ray buildup factor, is proposed. This model embraces nonuniform attenuation in a voxelized object of imaging (patient body) and multiple scattering that is treated as in the point-kernel integration gamma-ray shielding problems. First-order Compton scattering is done by means of the Klein-Nishina formula, but the multiple scattering is accounted for by making use of a dose buildup factor. An asset of the present model is the possibility of generating a complete two-dimensional (2D) PSF that can be used for 3D SPECT reconstruction by means of iterative algorithms. The proposed model is convenient in those situations where more exact techniques are not economical. For the proposed model's testing purpose calculations (for the point source in a nonuniform scattering object for parallel beam collimator geometry), the multiple-order scatter PSF generated by means of the proposed model matched well with those using Monte Carlo (MC) simulations. Discrepancies are observed only at the exponential tails mostly due to the high statistic uncertainty of MC simulations in this area, but not because of the inappropriateness of the model. PMID:17881800

Marinkovic, Predrag; Ilic, Radovan; Spaic, Rajko

2007-10-01

311

Giant Compton Shifts in Hyperbolic Metamaterial  

E-print Network

We study the Compton scattering of light by free electrons inside a hyperbolic medium. We demonstrate that the unconventional dispersion and local density of states of the electromagnetic modes in such media can lead to a giant Compton shift and dramatic enhancement of the scattering cross section. We develop an universal approach for the study of coupled multi-photon processes in nanostructured media and derive the spectral intensity function of the scattered radiation for realistic metamaterial structures. We predict the Compton shift of the order of a few meVs for the infrared spectrum that is at least one order of magnitude larger than the Compton shift in any other system.

Iorsh, Ivan; Ginzburg, Pavel; Belov, Pavel; Kivshar, Yuri

2014-01-01

312

Gamma Spectroscopy  

NSDL National Science Digital Library

Students use NaI/PMT gamma detectors to gather spectra of several radioactive sources. The full-enrgy peak, Compton edge, Compton shelf and backscatter peaks are identified. The physics of the detection process is emphasized.

Bistrow, Van

2009-01-05

313

Compton Modified Line Structure and its Relation to the Electron Theory of Solid Bodies  

Microsoft Academic Search

A tube especially designed for the study of the Compton effect at large angles of scattering.-The structure of the Compton line obtained with this tube for a scattering angle of nearly 180° with a metallic beryllium scatterer is shown. Interpretation of the structure of the Compton line.-The diffuse structure of the Compton line is here attributed to a broadening caused

Jesse W. Du Mond

1929-01-01

314

Noise evaluation of Compton camera imaging for proton therapy.  

PubMed

Compton Cameras emerged as an alternative for real-time dose monitoring techniques for Particle Therapy (PT), based on the detection of prompt-gammas. As a consequence of the Compton scattering process, the gamma origin point can be restricted onto the surface of a cone (Compton cone). Through image reconstruction techniques, the distribution of the gamma emitters can be estimated, using cone-surfaces backprojections of the Compton cones through the image space, along with more sophisticated statistical methods to improve the image quality. To calculate the Compton cone required for image reconstruction, either two interactions, the last being photoelectric absorption, or three scatter interactions are needed. Because of the high energy of the photons in PT the first option might not be adequate, as the photon is not absorbed in general. However, the second option is less efficient. That is the reason to resort to spectral reconstructions, where the incoming ? energy is considered as a variable in the reconstruction inverse problem. Jointly with prompt gamma, secondary neutrons and scattered photons, not strongly correlated with the dose map, can also reach the imaging detector and produce false events. These events deteriorate the image quality. Also, high intensity beams can produce particle accumulation in the camera, which lead to an increase of random coincidences, meaning events which gather measurements from different incoming particles. The noise scenario is expected to be different if double or triple events are used, and consequently, the reconstructed images can be affected differently by spurious data. The aim of the present work is to study the effect of false events in the reconstructed image, evaluating their impact in the determination of the beam particle ranges. A simulation study that includes misidentified events (neutrons and random coincidences) in the final image of a Compton Telescope for PT monitoring is presented. The complete chain of detection, from the beam particle entering a phantom to the event classification, is simulated using FLUKA. The range determination is later estimated from the reconstructed image obtained from a two and three-event algorithm based on Maximum Likelihood Expectation Maximization. The neutron background and random coincidences due to a therapeutic-like time structure are analyzed for mono-energetic proton beams. The time structure of the beam is included in the simulations, which will affect the rate of particles entering the detector. PMID:25658644

Ortega, P G; Torres-Espallardo, I; Cerutti, F; Ferrari, A; Gillam, J E; Lacasta, C; Llosá, G; Oliver, J F; Sala, P R; Solevi, P; Rafecas, M

2015-02-21

315

Calibration of a low-level anti-Compton underground gamma-spectrometer by experiment and Monte Carlo.  

PubMed

In this work we present the experimental and Monte Carlo calibration of the Compton-suppressed spectrometer of the IAEA's Environment Laboratories, Monaco. For this purpose the GESPECOR code was extended to include the specific geometry and to implement the veto logic, integrated with the coincidence summing module of the code. The simulation results are in good accordance with experimental calibrations. The code is fast and user-friendly, able to evaluate the efficiency and the correction factors for nuclides with arbitrary complex decay schemes. PMID:23548692

Sima, Octavian; Osvath, Iolanda

2013-11-01

316

Measurement of the Generalized Polarizabilities of the Proton in Virtual Compton Scattering at Q2= 0.92 and 1.76 GeV2  

SciTech Connect

We report a Virtual Compton Scattering study of the proton at low CM energies. We have determined the structure functions P{sub LL} - P{sub TT}/{epsilon} and P{sub LT}, and the electric and magnetic Generalized Polarizabilities (GPs) {alpha}{sub E}(Q{sup 2}) and {beta}{sub M}(Q{sup 2}) at momentum transfer Q{sup 2} = 0.92 and 1.76 GeV{sup 2}. The electric GP shows a strong fall-off with Q{sup 2}, and its global behavior does not follow a simple dipole form. The magnetic GP shows a rise and then a fall-off; this can be interpreted as the dominance of a long-distance diamagnetic pion cloud at low Q{sup 2}, compensated at higher Q{sup 2} by a paramagnetic contribution from {pi}N intermediate states.

Geraud Laveissiere; Natalie Degrande; Stephanie Jaminion; Christophe Jutier; Luminita Todor; Rachele Di Salvo; L. Van Hoorebeke; Et. Al.

2004-09-01

317

Inspection of reinforced concrete samples by Compton backscattering technique  

NASA Astrophysics Data System (ADS)

Reinforced concrete structures require frequent monitoring to ensure the concrete quality during its service life and for evaluation of in situ existing conditions. Compton backscattering of gamma rays is a nondestructive technique used for material characterization and detection of defects and inclusions in materials and can be employed on reinforced concrete. The methodology allows one-sided inspection of large structures, is relatively inexpensive and can be portable. The concept is based on detection of backscattered radiation produced from a collimated beam aimed at the sample. By measuring the spectrum of these scattered gamma rays it is possible to determine local density perturbations. In this work we used the Compton backscattering technique to locate and measure steel, defects and crushed stone inside concrete. The samples were irradiated with gamma rays from a Ø2 mm diameter collimated 241Am (100 mCi) source and the inelastically scattered photons were recorded at an angle of 135° by a high resolution CdTe semiconductor detector. Scanning was achieved by lateral movement of the sample blocks across the source and detector field of view in steps of 1 mm. A previous optimization of the experimental setup was performed with Monte Carlo simulation. The results showed that it was possible to locate inclusions and defects with Ø8 mm positioned at a depth of 20 mm below the surface of the sample. It was observed that aggregates such as crushed stone could mask defects at specific points due to high attenuation of the incident and scattered beam.

Boldo, E. M.; Appoloni, C. R.

2014-02-01

318

Statistical properties of the time histories of cosmic gamma-ray bursts detected by the BATSE experiment of the Compton gamma-ray observatory  

NASA Technical Reports Server (NTRS)

The main scientific objectives of the project were: (1) Calculation of average time history for different subsets of BATSE gamma-ray bursts; (2) Comparison of averaged parameters and averaged time history for different Burst And Transient Source Experiments (BASTE) Gamma Ray Bursts (GRB's) sets; (3) Comparison of results obtained with BATSE data with those obtained with APEX experiment at PHOBOS mission; and (4) Use the results of (1)-(3) to compare current models of gamma-ray bursts sources.

Sagdeev, Roald

1995-01-01

319

IEEE TRANSACTIONS ON NUCLEAR SCIENCE, VOL. 50, NO. 5, OCTOBER 2003 1609 Feasibility Study of Compton Scattering Enchanced  

E-print Network

selected pinhole spacing, the proposed detector design leads to an improved image quality. Index Terms or scattered. However, this uniqueness of information is achieved at the cost of losing all photons that do

He, Zhong

320

Nonrelativistic Compton scattering in Furry's picture. III. Kramers-Heisenberg transition amplitude by means of the complex-coordinate method  

NASA Astrophysics Data System (ADS)

The procedure for calculating the general Kramers-Heisenberg transition amplitude for scattering of light is presented. The procedure is based on L2 atomic structure calculations implemented within the framework of the complex-coordinate method, gives the transition amplitudes without explicit calculation of the final states, and includes the contribution from ? 2 terms, p¯? terms to second order, and interference terms between these scattering contributions.

Froelich, Piotr; Weyrich, Wolf

1986-08-01

321

Study of scattered photons from the collimator system of Leksell Gamma Knife using the EGS4 Monte Carlo Code  

E-print Network

Study of scattered photons from the collimator system of Leksell Gamma Knife using the EGS4 Monte Carlo Code Joel Y. C. Cheung Gamma Knife Centre, Canossa Hospital, 1 Old Peak Road, Hong Kong K. N. Yua Gamma Knife , scattered photons from the collimator system are presumed to have negligible effects

Yu, K.N.

322

Design Concept of a Gamma-gamma Higgs Factory Driven by Thin Laser Targets and Energy Recovery Linacs  

SciTech Connect

A gamma-gamma collider has long been considered an option for a Higgs Factory. Such photon colliders usually rely on Compton back-scattering for generating high energy gamma photons and further Higgs bosons through gamma-gamma collisions. The presently existing proposals or design concepts all have chosen a very thick laser target (i.e., high laser photon intensity) for Compton scatterings. In this paper, we present a new design concept of a gamma-gamma collider utilizing a thin laser target (i.e., relatively low photon density), thus leading to a low electron to gamma photon conversion rate. This new concept eliminates most useless and harmful low energy soft gamma photons from multiple Compton scattering so the detector background is improved. It also greatly relaxes the requirement of the high peak power of the laser, a significant technical challenge. A high luminosity for such a gamma-gamma collider can be achieved through an increase of the bunch repetition rate and current of the driven electron beam. Further, multi-pass recirculating linac could greatly reduce the linac cost and energy recovery is required to reduce the needed RF power.

Zhang, Yuhong [JLAB

2013-06-01

323

Experimental analysis of scattered photons in Tc-99m imaging with a gamma camera.  

PubMed

The amount of scattered photons in a clinical imaging window of Tc-99m was experimentally measured by means of a line source with scattering materials and a gamma camera. A symmetrical photopeak energy window centered at 140 keV with a width of 20% (126-154 keV) was partitioned into several small windows. Energy spectra were analyzed to determine the scatter fraction and the attenuation coefficient for each window. Line spread functions (LSF) were also obtained to characterize the spatial scatter distribution. The results of analysis of energy spectra show that scattered photons are included over the symmetric 20% window (SW) and scatter fractions increase linearly with the increasing thickness of the scattering material in all energy windows investigated. In addition, the results for the LSF show that the scatter distribution within the SW is represented as a mono-exponential function. Experimental measurements obtained with a phantom and a gamma camera simplify accurate quantification of scattered photons. Such quantitative analysis of scattered photons is important in developing and evaluating a scatter correction technique. PMID:1797068

Kojima, A; Matsumoto, M; Takahashi, M

1991-11-01

324

Stimulated Raman and Compton scattering of high energy laser beams in a disturbed ionospheric space plasma environment - Linear theory  

Microsoft Academic Search

The interaction of a high energy laser beam with the ionospheric space plasma environment is discussed. The plasma is considered to be inhomogeneous, underdense, collisional, and embedded in a magnetic field. Linear theory is used to compute the growth rates for stimulated Raman scattering and beam filamentation parametric instabilities using several values for laser beam intensity and disturbed ionospheric space

M. K. Keskinen; H. L. Rowland; P. K. Chaturvedi; Y. C. Lee

1989-01-01

325

Hadronic light-by-light scattering in the muon g-2: impact of proposed measurements of the (pi^0 -> gamma gamma) decay width and the (gamma^* gamma -> pi^0) transition form factor with the KLOE-2 experiment  

E-print Network

We discuss, how planned measurements at KLOE-2 of the (pi^0 -> gamma gamma) decay width and the (gamma^* gamma -> pi^0) transition form factor can improve estimates for the numerically dominant pion-exchange contribution to hadronic light-by-light scattering in the muon g-2 and what are the limitations related to the modelling of the off-shellness of the pion.

Nyffeler, Andreas

2012-01-01

326

Hadronic light-by-light scattering in the muon g-2: impact of proposed measurements of the (pi^0 -> gamma gamma) decay width and the (gamma^* gamma -> pi^0) transition form factor with the KLOE-2 experiment  

E-print Network

We discuss, how planned measurements at KLOE-2 of the (pi^0 -> gamma gamma) decay width and the (gamma^* gamma -> pi^0) transition form factor can improve estimates for the numerically dominant pion-exchange contribution to hadronic light-by-light scattering in the muon g-2 and what are the limitations related to the modelling of the off-shellness of the pion.

Andreas Nyffeler

2012-12-04

327

MIT inverse Compton source concept  

E-print Network

A compact X-ray source based on inverse Compton scattering of a high-power laser on a high-brightness linac beam is described. The facility can operate in two modes: at high (MHz) repetition rate with flux and brilliance ...

Graves, William S.

328

N-SAP and G-SAP neutron and gamma ray albedo model scatter shield analysis program  

NASA Technical Reports Server (NTRS)

Computer program calculates neutron or gamma ray first order scattering from a plane or cylindrical surface to a detector point. The SAP Codes, G-SAP and N-SAP, constitute a multiple scatter albedo model shield analysis.

Sapovchak, B. J.; Stephenson, L. D.

1967-01-01

329

Detection of high-energy gamma radiation from quasar 3C 279 by the EGRET telescope on the Compton Gamma Ray Observatory  

NASA Technical Reports Server (NTRS)

Intense gamma radiation has been observed from the direction of the quasar 3C 279 throughout the energy range from 30 MeV to over 5 GeV by the Energetic Gamma Ray Experiment Telescope (EGRET) during the period June 15-28, 1991. Its spectrum is well represented by a photon differential power-law exponent of 2.0 +/- 0.1, with a photon intensity above 100 MeV of (2.8 +/- 0.4) x 10 exp -6/sq cm s. For E is greater than 100 MeV, the 2-sigma upper limits were 1.0 x 10 exp -6/sq cm s in 1973 from the SAS 2 observations and 0.3 x 10 exp -6/sq cm s for the combined 1976, 1978, and 1980 COS B observations. Hence, there has been a large increase in high-energy gamma-ray intensity relative to the earlier times, as there has been in the radio, infrared, optical, and X-ray ranges. This source is the most distant and by far the most luminous gamma-ray source yet detected.

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

1992-01-01

330

Gamma-Ray Burst Arrival Time Localizations: Simultaneous Observations by {ital Pioneer} {ital V}{ital enus} {ital Orbiter}, {ital Compton} {ital Gamma}-{ital Ray} {ital Observatory}, and {ital Ulysses}  

SciTech Connect

Between the {ital Compton} {ital Gamma} {ital Ray} {ital Observatory} ({ital CGRO}) launch in 1991 April and the {ital Pioneer} {ital V}{ital enus} {ital Orbiter} ({ital PVO}) demise in 1992 October, concurrent coverage by {ital CGRO}, {ital PVO}, and {ital Ulysses} was obtained for several hundred gamma-ray bursts (GRBs). Although most of these were below the {ital PVO} and {ital Ulysses} thresholds, 37 were positively detected by all three spacecraft, with data quality adequate for quantitative localization analysis. All were localized independently to {approximately}2{degree} accuracy by the {ital 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{prime} to several degrees and whose smaller dimensions are in the arcminute range. Twelve have areas less than 10 arcmin{sup 2}, and only four have areas greater than 1 deg{sup 2}. The area of the smallest box is 0.44 arcmin{sup 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 {ital 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. {copyright} {ital {copyright} 1998.} {ital The American Astronomical Society}

Laros, J.G. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)] [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States); Hurley, K.C. [Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720-7450 (United States)] [Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720-7450 (United States); Fenimore, E.E.; Klebesadel, R.W. [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)] [Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Briggs, M.S. [University of Alabama in Huntsville, Huntsville, AL 35899 (United States)] [University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Kouveliotou, C.; McCollough, M.L. [USRA, at NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States)] [USRA, at NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Fishman, G.J.; Meegan, C.A. [NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States)] [NASA/Marshall Space Flight Center, Huntsville, AL 35812 (United States); Cline, T.L. [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)] [NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Boer, M.; Niel, M. [CESR, F-31029 Toulouse Cedex (France)] [CESR, F-31029 Toulouse Cedex (France)

1998-10-01

331

A library least-squares approach for scatter correction in gamma-ray tomography  

NASA Astrophysics Data System (ADS)

Scattered radiation is known to lead to distortion in reconstructed images in Computed Tomography (CT). The effects of scattered radiation are especially more pronounced in non-scanning, multiple source systems which are preferred for flow imaging where the instantaneous density distribution of the flow components is of interest. In this work, a new method based on a library least-squares (LLS) approach is proposed as a means of estimating the scatter contribution and correcting for this. The validity of the proposed method is tested using the 85-channel industrial gamma-ray tomograph previously developed at the University of Bergen (UoB). The results presented here confirm that the LLS approach can effectively estimate the amounts of transmission and scatter components in any given detector in the UoB gamma-ray tomography system.

Meric, Ilker; Anton Johansen, Geir; Valgueiro Malta Moreira, Icaro

2015-03-01

332

Compton amplifier  

NASA Astrophysics Data System (ADS)

An amplifier was developed for Compton detectors signals, used for the positioning of the electron beam of the linear accelerator MEA (Medium Energy Accelerator). The wire between detector and amplifier have to be about 30 m long due to radioactive radiation. The amplifier is broadband (60Hz to 2.3MHz), low noise (equivalent to 1 microA input current), and has a high common mode rejection (more than 80 dB); the inputs are galvanically separated with an input sensitivity of 1 microA. The signal to be detected is gated. Signals can be amplified to an output voltage of 5 V on 50 ohms with a 150 ms rise time.

Vanes, J. T.; Verkooijen, J. C.

1989-03-01

333

PLEIADES: A picosecond Compton scattering x-ray source for advanced backlighting and time-resolved material studies  

NASA Astrophysics Data System (ADS)

The PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility has produced first light at 70 keV. This milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as diagnostics for the National Ignition Facility and time-resolved material studies. The electron beam was focused to 50 ?m rms, at 57 MeV, with 260 pC of charge, a relative energy spread of 0.2%, and a normalized emittance of 5 mm mrad horizontally and 13 mm mrad vertically. The scattered 820 nm laser pulse had an energy of 180 mJ and a duration of 54 fs. Initial x rays were captured with a cooled charge-coupled device using a cesium iodide scintillator; the peak photon energy was approximately 78 keV, with a total x-ray flux of 1.3×106 photons/shot, and the observed angular distribution found to agree very well with three-dimensional codes. Simple K-edge radiography of a tantalum foil showed good agreement with the theoretical divergence-angle dependence of the x-ray energy. Optimization of the x-ray dose is currently under way, with the goal of reaching 108 photons/shot and a peak brightness approaching 1020 photons/mm2/mrad2/s/0.1% bandwidth.

Gibson, David J.; Anderson, Scott G.; Barty, Christopher P. J.; Betts, Shawn M.; Booth, Rex; Brown, Winthrop J.; Crane, John K.; Cross, Robert R.; Fittinghoff, David N.; Hartemann, Fred V.; Kuba, Jaroslav; Le Sage, Gregory P.; Slaughter, Dennis R.; Tremaine, Aaron M.; Wootton, Alan J.; Hartouni, Edward P.; Springer, Paul T.; Rosenzweig, James B.

2004-05-01

334

Compton Scattering on ^209Bi at HI?S From E?=11-30 MeV  

NASA Astrophysics Data System (ADS)

New data collected at the High Intensity ?-ray Source (HI?S) were taken to investigate the Iso-Vector Giant Dipole (IVGDR) and Giant Quadrupole (IVGQR) Resonance Regions in ^209Bi, E?=11-30 MeV. Linearly polarized ?-rays were incident upon an isotopically pure (>99.9%) ^209Bi target and the scattered ?-rays were detected using the HI?S NaI Detector Array (HINDA). HINDA is an array of large (10''x10'') core detectors surrounded by 3'' thick NaI shields that are segmented optically into 8 individual segments. This assembly was run in an anti-coincidence mode to reduce background and improve the resolution as well as a coincidence mode to isolate the first escape peak. During the 150 hour run, the nearly mono-energetic ?-ray intensities were 1x10^5-1x10^7?'s/sec on target and statistical accuracies of 1-3% were achieved. Preliminary analysis of angular distributions of cross sections and analyzing powers as well as absolute cross sections will be reported.

Henshaw, S. S.; Ahmed, M. W.; Brown, N.; Perdue, B. A.; Stave, S.; Weller, H. R.; Martel, P. P.; Teymurazyan, A.; Miskimen, R.; Prior, R. M.; Spraker, M. C.; Pywell, R.; Feldman, G.; Nathan, A. M.; Whisnant, S.

2009-10-01

335

Development of polarization-controlled multi-pass Thomson scattering system in the GAMMA 10 tandem mirror  

SciTech Connect

In the GAMMA 10 tandem mirror, the typical electron density is comparable to that of the peripheral plasma of torus-type fusion devices. Therefore, an effective method to increase Thomson scattering (TS) signals is required in order to improve signal quality. In GAMMA 10, the yttrium-aluminum-garnet (YAG)-TS system comprises a laser, incident optics, light collection optics, signal detection electronics, and a data recording system. We have been developing a multi-pass TS method for a polarization-based system based on the GAMMA 10 YAG TS. To evaluate the effectiveness of the polarization-based configuration, the multi-pass system was installed in the GAMMA 10 YAG-TS system, which is capable of double-pass scattering. We carried out a Rayleigh scattering experiment and applied this double-pass scattering system to the GAMMA 10 plasma. The integrated scattering signal was made about twice as large by the double-pass system.

Yoshikawa, M.; Morimoto, M.; Shima, Y.; Kohagura, J.; Sakamoto, M.; Nakashima, Y.; Imai, T. [Plasma Research Center, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8577 (Japan); Yasuhara, R.; Yamada, I.; Kawahata, K.; Funaba, H. [National Institute for Fusion Science, 322-6 Oroshi-cho, Toki, Gifu 509-5292 (Japan); Minami, T. [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan)

2012-10-15

336

Constrained {gamma}Z correction to parity-violating electron scattering  

SciTech Connect

We update the calculation of {gamma}Z interference corrections to the weak charge of the proton. We show how constraints from parton distributions, together with new data on parity-violating electron scattering in the resonance region, significantly reduce the uncertainties on the corrections compared to previous estimates.

Hall, Nathan Luk [Adelaide U.; Blunden, Peter Gwithian [Manitoba U.; Melnitchouk, Wally [JLAB; Thomas, Anthony W. [Adelaide U.; Young, Ross D. [Adelaide U.

2013-11-01

337

Neutron-neutron scattering length from the reaction gamma d --> pi^+ nn employing chiral perturbation theory  

E-print Network

We discuss the possibility to extract the neutron-neutron scattering length a_{nn} from experimental spectra on the reaction gamma d --> pi^+ nn. The transition operator is calculated to high accuracy from chiral perturbation theory. We argue that for properly chosen kinematics, the theoretical uncertainty of the method can be as low as 0.1 fm.

V. Lensky; V. Baru; E. Epelbaum; C. Hanhart; J. Haidenbauer; A. Kudryavtsev; Ulf-G. Meißner

2007-04-03

338

Performance evaluation of a pixellated Ge Compton camera  

NASA Astrophysics Data System (ADS)

An ongoing project is being carried out to develop a high purity germanium (HPGe) Compton camera for medical applications. The Compton camera offers many potential advantages over the conventional gamma camera. The camera reported in this paper comprises two pixellated germanium detector planes housed 9.6 cm apart in the same vacuum housing. The camera has 177 pixels, 152 in the scatter detector and 25 in the absorption detector. The pixels are 4 × 4 mm2 with a thickness of 4 mm in the scatter detector and 10 mm in the absorption detector. Images have been taken for a variety of test objects including point sources, a ring source and a Perspex phantom. The measured angular resolution is 9.4° ± 0.4° for a 662 keV gamma-ray source at 3 cm. Due to the limited number of readout modules a multiple-view technique was used to image the source distributions from different angles and simulate the pixel arrangement in the full camera.

Alnaaimi, M. A.; Royle, G. J.; Ghoggali, W.; Banoqitah, E.; Cullum, I.; Speller, R. D.

2011-06-01

339

A multiple voxel model for scattered gamma radiation in pipe flow  

NASA Astrophysics Data System (ADS)

A multiple voxel model for scattered gamma radiation in pipe flow has been developed. The model has been used in the development of the dual modality densitometry measurement principle. In this measurement principle the gas volume fraction and the water salinity of an oil/water/gas pipe flow are measured by combining measurements of the intensity of scattered and transmitted radiation. The model has been applied to two different measurement geometries. The purpose of the model is to predict the intensity of scattered radiation at a detector position and to produce a three-dimensional spatial sensitivity map of the scatter generation. This is done by dividing the measurement volume into small cubic volumes; voxels. The contribution to the measured intensity of scattered radiation from each voxel is calculated and integrated for all voxels. The model has been verified by comparing with experiments and Monte Carlo simulations.

Tjugum, S. A.; Johansen, G. A.; Holstad, M. B.

2003-10-01

340

A double photomultiplier Compton camera and its readout system for mice imaging  

SciTech Connect

We have designed a Compton Camera (CC) to image the bio-distribution of gamma-emitting radiopharmaceuticals in mice. A CC employs the 'electronic collimation', i.e. a technique that traces the gamma-rays instead of selecting them with physical lead or tungsten collimators. To perform such a task, a CC measures the parameters of the Compton interaction that occurs in the device itself. At least two detectors are required: one (tracker), where the primary gamma undergoes a Compton interaction and a second one (calorimeter), in which the scattered gamma is completely absorbed. Eventually the polar angle and hence a 'cone' of possible incident directions are obtained (event with 'incomplete geometry'). Different solutions for the two detectors are proposed in the literature: our design foresees two similar Position Sensitive Photomultipliers (PMT, Hamamatsu H8500). Each PMT has 64 output channels that are reduced to 4 using a charge multiplexed readout system, i.e. a Series Charge Multiplexing net of resistors. Triggering of the system is provided by the coincidence of fast signals extracted at the last dynode of the PMTs. Assets are the low cost and the simplicity of design and operation, having just one type of device; among drawbacks there is a lower resolution with respect to more sophisticated trackers and full 64 channels Readout. This paper does compare our design of our two-Hamamatsu CC to other solutions and shows how the spatial and energy accuracy is suitable for the inspection of radioactivity in mice.

Fontana, Cristiano Lino [Physics Department Galileo Galilei, University of Padua, Via Marzolo 8, Padova 35131 (Italy) and INFN Padova, Via Marzolo 8, Padova 35131 (Italy); Atroshchenko, Kostiantyn [Physics Department Galileo Galilei, University of Padua, Via Marzolo 8, Padova 35131 (Italy) and INFN Legnaro, Viale dell'Universita 2, Legnaro PD 35020 (Italy); Baldazzi, Giuseppe [Physics Department, University of Bologna, Viale Berti Pichat 6/2, Bologna 40127, Italy and INFN Bologna, Viale Berti Pichat 6/2, Bologna 40127 (Italy); Bello, Michele [INFN Legnaro, Viale dell'Universita 2, Legnaro PD 35020 (Italy); Uzunov, Nikolay [Department of Natural Sciences, Shumen University, 115 Universitetska str., Shumen 9712, Bulgaria and INFN Legnaro, Viale dell'Universita 2, Legnaro PD 35020 (Italy); Di Domenico, Giovanni [Physics Department, University of Ferrara, Via Saragat 1, Ferrara 44122 (Italy) and INFN Ferrara, Via Saragat 1, Ferrara 44122 (Italy)

2013-04-19

341

Inelastic neutron scatter iron concentrations of the moon from orbital gamma ray data  

NASA Technical Reports Server (NTRS)

The considered investigation is concerned with the relation between KREEP and thermal neutron flux depression. The Fe(n, n-prime gamma) concentrations of selected lunar regions were calculated by energy-band analysis of the 0.803-0.872 MeV band. The result of the investigation will be used to evaluate the reliability of the previously determined Fe(n, gamma) values. A 0.803-0.872 MeV band was isolated from the Apollo 15 and 16 orbital gamma ray spectra. Preliminary regression analysis of regional ground truth count rates and Fe concentrations showed this energy interval to be optimum for the 0.8467 MeV inelastic scatter (n, n-prime gamma)Fe peak.

Davis, P. A., Jr.; Bielefeld, M. J.

1981-01-01

342

Testing the DC-electric field model in a solar flare observed by Yohkoh and the Compton Gamma-Ray Observatory  

NASA Technical Reports Server (NTRS)

We apply a DC-electric field model to the analysis of soft and hard X-ray observations of a solar flare observed by Yohkoh and the Compton Gamma Ray Observatory (CGRO) on 6 September 1992. The flare was observed simultaneously in the soft X-ray Ca XIX line by the Yohkoh Bragg Crystal Spectrometer (BCS) and in hard X-rays (greater than 50 keV) by the CGRO Burst and Transient Spectrometer Experiment (BATSE). A strong stationary component of Ca XIX emission was present at the start of impulsive hard X-ray emission indicating an extended phase of heating prior to the production of energetic nonthermal electrons. We interpret the preflare Ca XIX emission as a signature of Joule heating by field-aligned currents. We relate the temporal variation of impulsive hard X-ray emission to the rate of runaway electron acceleration by the DC-electric field associated with the current. We find that the initial rise in hard X-ray emission is consistent with electron acceleration by a DC-electric field that increased from a preflare value of less than approximately 10(exp -5) V/cm to approximately (9 +/- 1) x 10(exp -5) V/cm at the time of the first hard X-ray peak and then remained constant during the rest of the impulsive phase. We attribute the increase in electric field strength to the formation of a current sheet at the reconnection point of two loop structures. The decrease in hard X-ray emission after flare maximum is consistent with a reduction in the number of runaway electrons due to an increase in coronal density produced by chromospheric evaporation. The increased density quenches the runaway process by enhancing collisional thermalization of electrons. To avoid the generation of an unrealistically large magnetic field, the flaring region must be highly filamented into greater than approximately 10(exp 6) oppositely directed current channels of approximately 30 cm width with an initial preflare current of approximately 3 x 10(exp 10) A per channel.

Zarro, D. M.; Mariska, J. T.; Dennis, B. R.

1995-01-01

343

A Non-Relativistic Look at the Compton Effect  

NASA Astrophysics Data System (ADS)

In a usual modern physics class the Compton effect is used as the pedagogical model for introducing relativity into quantum effects. The shift in photon wavelengths is usually introduced and derived using special relativity. Indeed, this works well for explaining the effect. However, in the senior author's class one of the student coauthors of this paper, Sandeep Giri, asked what would happen if classical expressions for the electrons' momentum (mv) and kinetic energy [(1/2)mv2] were used. The first response given to the question was that the relevant energies were relativistic and hence this approach would not work. Further thought led to the realization that the electron receives only the difference in the energies of the incoming and outgoing photons. This left the initial conclusion in doubt and we began a serious look at what would the answer be. As a result of our analyses, we believe that the Compton effect provides the clearest pedagogical test for the need of relativity in the case of gamma ray scattering while allowing both the classical and relativistic results to explain the original x-ray results of Compton.

Feller, Steve; Giri, Sandeep; Zakrasek, Nicholas; Affatigato, Mario

2014-01-01

344

A two-pixel Compton imager  

NASA Astrophysics Data System (ADS)

We are designing a Compton imager for use in security investigations and in radiological incident remediation. Previously, results from simulations of a system consisting of several layers of pixellated solid scintillator for both the scatter and absorber detectors were reported. We have now established a two-pixel test stand for validation of the simulations. The stand consists of a single scatter pixel fixed in space, and a single absorber pixel affixed to a two-dimensional translator. Automated translation of the absorber pixel to different positions allows for the acquisition of data at multiple Compton scattering angles, thereby building up a dataset from an effectively multi-channel Compton imager. Here we present performance characteristics for an imager composed of a single 1 cm3 pixel of NaI(Tl) for the scatter detector, and a single 1 cm3 pixel of LaBr3 for the absorber detector.

Saull, P. R. B.; Sinclair, L. E.; Seywerd, H. C. J.; Boyle, P. J.; MacLeod, A. M. L.; Hanna, D. S.

2010-04-01

345

Intercomparison of gamma scattering, gammatography, and radiography techniques for mild steel nonuniform corrosion detection  

NASA Astrophysics Data System (ADS)

This paper focuses on the mild steel (MS) corrosion detection and intercomparison of results obtained by gamma scattering, gammatography, and radiography techniques. The gamma scattering non-destructive evaluation (NDE) method utilizes scattered gamma radiation for the detection of corrosion, and the scattering experimental setup is an indigenously designed automated personal computer (PC) controlled scanning system consisting of computerized numerical control (CNC) controlled six-axis source detector system and four-axis job positioning system. The system has been successfully used to quantify the magnitude of corrosion and the thickness profile of a MS plate with nonuniform corrosion, and the results are correlated with those obtained from the conventional gammatography and radiography imaging measurements. A simple and straightforward reconstruction algorithm to reconstruct the densities of the objects under investigation and an unambiguous interpretation of the signal as a function of material density at any point of the thick object being inspected is described. In this simple and straightforward method the density of the target need not be known and only the knowledge of the target material's mass attenuation coefficients (composition) for the incident and scattered energies is enough to reconstruct the density of the each voxel of the specimen being studied. The Monte Carlo (MC) numerical simulation of the phenomena is done using the Monte Carlo N-Particle Transport Code (MCNP) and the quantitative estimates of the values of signal-to-noise ratio for different percentages of MS corrosion derived from these simulations are presented and the spectra are compared with the experimental data. The gammatography experiments are carried out using the same PC controlled scanning system in a narrow beam, good geometry setup, and the thickness loss is estimated from the measured transmitted intensity. Radiography of the MS plates is carried out using 160 kV x-ray machine. The digitized radiographs with a resolution of 50 ?m are processed for the detection of corrosion damage in five different locations. The thickness losses due to the corrosion of the MS plate obtained by gamma scattering method are compared with those values obtained by gammatography and radiography techniques. The percentage thickness loss estimated at different positions of the corroded MS plate varies from 17.78 to 27.0, from 18.9 to 24.28, and from 18.9 to 24.28 by gamma scattering, gammatography, and radiography techniques, respectively. Overall, these results are consistent and in line with each other.

Priyada, P.; Margret, M.; Ramar, R.; Shivaramu, Menaka, M.; Thilagam, L.; Venkataraman, B.; Raj, Baldev

2011-03-01

346

First results of electron temperature measurements by the use of multi-pass Thomson scattering system in GAMMA 10a)  

NASA Astrophysics Data System (ADS)

A multi-pass Thomson scattering (TS) has the advantage of enhancing scattered signals. We constructed a multi-pass TS system for a polarisation-based system and an image relaying system modelled on the GAMMA 10 TS system. We undertook Raman scattering experiments both for the multi-pass setting and for checking the optical components. Moreover, we applied the system to the electron temperature measurements in the GAMMA 10 plasma for the first time. The integrated scattering signal was magnified by approximately three times by using the multi-pass TS system with four passes. The electron temperature measurement accuracy is improved by using this multi-pass system.

Yoshikawa, M.; Yasuhara, R.; Nagasu, K.; Shimamura, Y.; Shima, Y.; Kohagura, J.; Sakamoto, M.; Nakashima, Y.; Imai, T.; Ichimura, M.; Yamada, I.; Funaba, H.; Kawahata, K.; Minami, T.

2014-11-01

347

Range verification of passively scattered proton beams using prompt gamma-ray detection.  

PubMed

We performed an experimental study to verify the range of passively scattered proton beams by detecting prompt gamma-rays emitted from proton-nuclear interactions. A method is proposed using a single scintillation detector positioned near the distal end of the irradiated target. Lead shielding was used to attenuate gamma-rays emitted along most of the entrance path of the beam. By synchronizing the prompt gamma-ray detector to the rotation of the range modulation wheel, the relation between the gamma emission from the distal part of the target and the range of the incident proton beam was determined. In experiments with a water phantom and an anthropomorphic head phantom, this relation was found to be sensitive to range shifts that were introduced. The wide opening angle of the detector enabled a sufficient signal-to-background ratio to be achieved in the presence of neutron-induced background from the scattering and collimating devices. Uniform range shifts were detected with a standard deviation of 0.1 mm to 0.2 mm at a dose level of 30 cGy to 50 cGy (RBE). The detectable magnitude of a range shift limited to a part of the treatment field area was approximately proportional to the ratio between the field area and the area affected by the range shift. We conclude that it is feasible to detect changes in the range of passively scattered proton beams using a relatively simple prompt gamma-ray detection system. The method can be employed for in vivo verification of the consistency of the delivered range in fractionated treatments. PMID:25585521

Verburg, Joost M; Testa, Mauro; Seco, Joao

2015-02-01

348

Range verification of passively scattered proton beams using prompt gamma-ray detection  

NASA Astrophysics Data System (ADS)

We performed an experimental study to verify the range of passively scattered proton beams by detecting prompt gamma-rays emitted from proton-nuclear interactions. A method is proposed using a single scintillation detector positioned near the distal end of the irradiated target. Lead shielding was used to attenuate gamma-rays emitted along most of the entrance path of the beam. By synchronizing the prompt gamma-ray detector to the rotation of the range modulation wheel, the relation between the gamma emission from the distal part of the target and the range of the incident proton beam was determined. In experiments with a water phantom and an anthropomorphic head phantom, this relation was found to be sensitive to range shifts that were introduced. The wide opening angle of the detector enabled a sufficient signal-to-background ratio to be achieved in the presence of neutron-induced background from the scattering and collimating devices. Uniform range shifts were detected with a standard deviation of 0.1 mm to 0.2 mm at a dose level of 30 cGy to 50 cGy (RBE). The detectable magnitude of a range shift limited to a part of the treatment field area was approximately proportional to the ratio between the field area and the area affected by the range shift. We conclude that it is feasible to detect changes in the range of passively scattered proton beams using a relatively simple prompt gamma-ray detection system. The method can be employed for in vivo verification of the consistency of the delivered range in fractionated treatments.

Verburg, Joost M.; Testa, Mauro; Seco, Joao

2015-02-01

349

Compton imager for detection of special nuclear material  

NASA Astrophysics Data System (ADS)

A Compton imager design for the detection of Special Nuclear Material (SNM), with specific focus on shielded Highly Enriched Uranium (HEU) is presented. It is based on a large field-of-view Compton gamma-ray imager that uses 24 layers of 2 mm thick, position-sensitive (1.4 mm strips) silicon detectors, designed for room-temperature operation, as a scatterer and a position-sensitive NaI scintillator array as the absorber. Each layer of silicon detectors consists of double-sided silicon strip detectors daisy chained in a 3×3 array with a total active area of 729 cm 2. The NaI detectors are 2.9×2.9 cm 2 and 7.6 cm thick and will cover the bottom and sides of the instrument. Simulations of an ASIC-based readout system show that an energy resolution of 4.5 keV full-width at half-maximum (FWHM) at room temperature is attainable on each daisy-chained silicon strip assuming 35 pF of capacitance and 20 nA of leakage current. Full simulations of the current instrument design are shown and are demonstrated that it can detect 8 kg of shielded HEU at 2.5 m in 1 min in a realistic gamma-ray background environment.

Wulf, Eric A.; Phlips, Bernard F.; Neil Johnson, W.; Kurfess, James D.; Novikova, Elena I.; O'Connor, Paul; De Geronimo, Gianluigi

2007-08-01

350

Spin momentum density of Nd using Compton spectroscopy  

SciTech Connect

Spin momentum density of Nd has been measured at 6K temperature using magnetic Compton scattering. The individual contribution of different electronic states, in the formation of total spin moment, is deduced from the analysis of magnetic Compton profile. The electron-specific spin moments deduced from the experimental Compton data are compared with the theoretical results obtained from full potential linearized augmented plane wave method and are found to be in good agreement.

Sahariya, Jagrati; Dashora, Alpa; Mund, H. S.; Ahuja, B. L. [Department of Physics, ML Sukhadia University, Udaipur-313001, Rajasthan (India); Tiwari, Shailja [Department of Physics, Govt. Women Engineering College, Ajmer-305001, Rajasthan (India); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

2013-02-05

351

Design of a coded aperture Compton telescope imaging system (CACTIS)  

NASA Astrophysics Data System (ADS)

We have developed a prototype of a scalable high-resolution direction and energy sensitive gamma-ray detection system that operates in both coded aperture (CA) and Compton scatter (CS) modes to obtain optimal efficiency and angular resolution over a wide energy range. The design consists of an active coded aperture constructed from 52 individual CZT planar detectors each measuring 3×3×6 mm3 arranged in a MURA pattern on a 10×10 grid, with a monolithic 20×20×5 mm3 pixelated (8×8) CZT array serving as the focal plane. The combined mode is achieved by using the aperture plane array for both Compton scattering of high-energy photons and as a coded mask for low-energy radiation. The prototype instrument was built using two RENA-3 test systems, one each for the aperture and the focal plane, stacked on top of each other at a distance of 130 mm. The test systems were modified to coordinate (synchronize) readout and provide coincidence information of events within a user-adjustable 40-1,280 ns window. The measured angular resolution of the device is <1 deg (17 mrad) in CA mode and is predicted to be approximately 3 deg (54 mrad) in CS mode. The energy resolution of the CZT detectors is approximately 5% FWHM at 120 keV. We will present details of the system design and initial results for the calibration and performance of the prototype.

Volkovskii, Alexander; Clajus, Martin; Gottesman, Stephen R.; Malik, Hans; Schwartz, Kenneth; Tumer, Evren; Tumer, Tumay; Yin, Shi

2010-08-01

352

Inverse Compton Cross Section Revisited  

NASA Astrophysics Data System (ADS)

The design of advanced machines working in the quantum regime (ELI-NP, IRIDE, e - ? and ? - ? colliders) requires to set the fundamentals needed to have an accurate prediction of the radiation qualities after the Compton scattering. Due to the high energy of the electron beam in the cases above mentioned, the quantum effects, referred as inverse Compton, which occur during the collision with the laser radiation, are not negligible. We present a rigorous method to obtain the inverse Compton cross section in the general case of not null initial momentum of the electrons from a pure QED calculation, avoiding the usual approaches based on the derivation of this cross section either from the Klein and Nishina formula and the Lorentz transformations or throught Feynman diagrams and Mandelstam invariants. In the derivation of the cross section from the transition amplitude we pay particular attention to the long time behavior of the system evolution. Proceeding in this way we obtain the transition probability in the time unit, which integrated over the solid angle of emission defines spectrum and number of the scattered photons.

Curatolo, C.; Lanz, L.; Petrillo, V.

353

Discrimination of gamma rays due to inelastic neutron scattering in AGATA  

E-print Network

Possibilities of discriminating neutrons and gamma rays in the AGATA gamma-ray tracking spectrometer have been investigated with the aim of reducing the background due to inelastic scattering of neutrons in the high-purity germanium crystals. This background may become a serious problem especially in experiments with neutron-rich radioactive ion beams. Simulations using the Geant4 toolkit and a tracking program based on the forward tracking algorithm were carried out by emitting neutrons and gamma rays from the center of AGATA. Three different methods were developed and tested in order to find 'fingerprints' of the neutron interaction points in the detectors. In a simulation with simultaneous emission of six neutrons with energies in the range 1-5 MeV and ten gamma rays with energies between 150 and 1450 keV, the peak-to-background ratio at a gamma-ray energy of 1.0 MeV was improved by a factor of 2.4 after neutron rejection with a reduction of the photopeak efficiency at 1.0 MeV of only a factor of 1.25.

A. Ataç; A. Ka?ka?; S. Akkoyun; M. ?enyi?it; T. Hüyük; S. O. Kara; J. Nyberg

2009-06-10

354

Exact Solutions of the Kompaneets Equation for Photon "Comptonization" Kinetics  

NASA Astrophysics Data System (ADS)

The nonlinear Kompaneets equation for the evolution of the spectrum of a photon gas with Compton scattering in a rarefied nonrelativistic electron plasma (i.e., the "comptonization" of the radiation) is examined. Exact solutions of this equation are obtained by separation of variables. The solutions are expressed in terms of transcendental Heun and Bessel functions.

Dubinov, A. E.; Kitayev, I. N.

2014-09-01

355

Hadronic light-by-light scattering in the muon g-2: impact of proposed measurements of the (pi^0 -> gamma gamma) decay width and the (gamma^* gamma -> pi^0) transition form factor with the KLOE-2 experiment  

E-print Network

The calculation of the hadronic light-by-light scattering contribution to the muon g-2 currently relies entirely on models. Measurements of the form factors which describe the interactions of hadrons with photons can help to constrain the models and reduce the uncertainty in a_{mu}(had. LbyL) = (116 \\pm 40) x 10^{-11}. In the dominant pion-exchange contribution, the form factor F_{{pi^0}^*gamma^*gamma^*}((q_1 + q_2)^2, q_1^2, q_2^2) with an off-shell pion enters. In general, measurements of the transition form factor F(Q^2) = F_{{pi^0}^*gamma^*gamma^*}(m_{pi}^2, -Q^2, 0) are only sensitive to a subset of the model parameters. Thus, having a good description for F(Q^2) is only necessary, not sufficient, to determine a_{mu}(LbyL; pi^0). Simulations have shown that measurements at KLOE-2 should be able to determine the (pi^0 -> gamma gamma) decay width to 1% statistical precision and the transition form factor for small space-like momenta, 0.01 GeV^2 gamma gamma) decay width from the PDG [PrimEx] and current da...

Nyffeler, Andreas

2013-01-01

356

Modeled Performance of a Compton Telescope Based on Planar Germanium Detectors  

NASA Astrophysics Data System (ADS)

A Monte Carlo technique for modeling the gamma-ray background spectra in space-based gamma-ray telescopes has been developed. The background spectrum is one of the key factors to the ultimate sensitivity that gamma-ray telescopes can achieve. The major sources of background are the diffuse cosmic gamma-ray flux, the Earth's atmospheric flux, and the decay of nuclei produced by spallation of cosmic rays, trapped protons and their secondary particles, the decay of nuclei produced by neutron capture and the de-excitation of excited states produced by inelastic scattering of neutrons. All of these sources are included in the model. The method for calculating the nuclear activation and decay component of the background combines the low Earth orbit primary proton and neutron flux, the production of secondary hadrons with GEANT, the spallation cross sections from Alice91 and YieldX, nuclear decay data from National Nuclear Data Center's (NNDC) Evaluated Nuclear Structure Data Files (ENSDF) database, and three-dimensional gamma-ray and beta particle transport with Electron Gamma-ray Shower version 4 (EGS4) using MORSE-CG. The background in the High Energy Astrophysics Observatory 3 (HEAO 3) gamma-ray instrument was modeled and compared to the measured background to validate the code. HEAO 3 is a space-based germanium spectrometer surrounded by active scintillators that provide shielding. Both the active and passive components of the HEAO 3 instrument are included in the simulation. The measured background from the HEAO 3 space instrument is compared with the simulation. This Monte Carlo code handles the following decay types: electron capture, beta-, beta+, meta-stable isotopes and short lived meta-stable decay products, and isotopes that have branchings to both beta- and beta+. The code follows a cascade of photons to the ground state of the decay product, and propagates these photons and appropriate accompanying beta simultaneously. This model was applied to the design of an advanced Compton telescope (proposed as the ATHENA mission) to predict its performance capabilities. The effective area, background, and point spread function (the imaged response to a point source) were modeled for several configurations of this Compton telescope. Thus, the sensitivity of these different configurations of this Compton telescope were compared. The sensitivity of the best configurations of this advanced Compton telescope are ~3×10-7 gamma-rays s-1 cm-2 which is nearly 100 times more sensitivity than previous gamma-ray instruments.

Graham, Bradley L.

357

Study of scattered photons from the collimator system of Leksell Gamma Knife using the EGS4 Monte Carlo Code  

SciTech Connect

In the algorithm of Leksell GAMMAPLAN (the treatment planning software of Leksell Gamma Knife), scattered photons from the collimator system are presumed to have negligible effects on the Gamma Knife dosimetry. In this study, we used the EGS4 Monte Carlo (MC) technique to study the scattered photons coming out of the single beam channel of Leksell Gamma Knife. The PRESTA (Parameter Reduced Electron-Step Transport Algorithm) version of the EGS4 (Electron Gamma Shower version 4) MC computer code was employed. We simulated the single beam channel of Leksell Gamma Knife with the full geometry. Primary photons were sampled from within the {sup 60}Co source and radiated isotropically in a solid angle of 4{pi}. The percentages of scattered photons within all photons reaching the phantom space using different collimators were calculated with an average value of 15%. However, this significant amount of scattered photons contributes negligible effects to single beam dose profiles for different collimators. Output spectra were calculated for the four different collimators. To increase the efficiency of simulation by decreasing the semiaperture angle of the beam channel or the solid angle of the initial directions of primary photons will underestimate the scattered component of the photon fluence. The generated backscattered photons from within the {sup 60}Co source and the beam channel also contribute to the output spectra.

Cheung, Joel Y.C.; Yu, K.N. [Gamma Knife Centre, Canossa Hospital, 1 Old Peak Road, Hong Kong (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon Tong, Hong Kong (China)

2006-01-15

358

A Monte Carlo evaluation of three Compton camera absorbers.  

PubMed

We present a quantitative study on the performance of cadmium zinc telluride (CZT), thallium-doped sodium iodide (NaI(Tl)) and germanium (Ge) detectors as potential Compton camera absorbers. The GEANT4 toolkit was used to model the performance of these materials over the nuclear medicine energy range. CZT and Ge demonstrate the highest and lowest efficiencies respectively. Although the best spatial resolution was attained for Ge, its lowest ratio of single photoelectric to multiple interactions suggests that it is most prone to inter-pixel cross-talk. In contrast, CZT, which demonstrates the least positioning error due to multiple interactions, has a comparable spatial resolution with Ge. Therefore, we modelled a Compton camera system based on silicon (Si) and CZT as the scatterer and absorber respectively. The effects of the detector parameters of our proposed system on image resolution were evaluated and our results show good agreement with previous studies. Interestingly, spatial resolution which accounted for the least image degradation at 140.5 keV became the dominant degrading factor at 511 keV, indicating that the absorber parameters play some key roles at higher energies. The results of this study have validated the predictions by An et al. which state that the use of a higher energy gamma source together with reduction of the absorber segmentation to sub-millimetre could achieve the image resolution of 5 mm required in medical imaging. PMID:21710232

Uche, C Z; Round, W H; Cree, M J

2011-09-01

359

Messung des Asymmetrie-Koeffizienten der beta-gamma-Zirkularpolarisationskorrelation an erlaubten beta-Übergängen  

Microsoft Academic Search

The asymmetry coefficient of the beta-circularly-polarized gamma-correlation of allowed beta-decays has been measured for several nuclides with high accuracy. The polarimeter was a new type. Here the magnet is used as Compton-scatterer and as beta-spectrometer at the same time with the advantage that one has four coincidence possibilities between two gamma- and two beta-counters. The results of the measurements are

H. Behrens

1967-01-01

360

Gamma ray production cross-sections associated with multiple inelastic scattering of 14 MeV neutrons in lead  

NASA Astrophysics Data System (ADS)

The gamma ray angular distributions and differential production cross-sections have been measured for the inelastic scattering of 14 MeV neutrons in lead, using a gamma ray spectrometer based on an associated particle time-of-flight gating technique. The variation of cross-section with sample thickness was measured and the results compared with the predictions of the Monte Carlo computer code MORSE.

Warner, P. C.; Cox, A. J.

1985-11-01

361

The Design of Diamond Compton Telescope  

E-print Network

We have developed radiation detectors using the new synthetic diamonds. The diamond detector has an advantage for observations of "low/medium" energy gamma rays as a Compton telescope. The primary advantage of the diamond detector can reduce the photoelectric effect in the low energy range, which is background noise for tracking of the Compton recoil electron. A concept of the Diamond Compton Telescope (DCT) consists of position sensitive layers of diamond-striped detector and calorimeter layer of CdTe detector. The key part of the DCT is diamond-striped detectors with a higher positional resolution and a wider energy range from 10 keV to 10 MeV. However, the diamond-striped detector is under development. We describe the performance of prototype diamond detector and the design of a possible DCT evaluated by Monte Carlo simulations.

Hibino, Kinya; Okuno, Shoji; Yajima, Kaori; Uchihori, Yukio; Kitamura, Hisashi; Takashima, Takeshi; Yokota, Mamoru; Yoshida, Kenji

2007-01-01

362

The Design of Diamond Compton Telescope  

E-print Network

We have developed radiation detectors using the new synthetic diamonds. The diamond detector has an advantage for observations of "low/medium" energy gamma rays as a Compton telescope. The primary advantage of the diamond detector can reduce the photoelectric effect in the low energy range, which is background noise for tracking of the Compton recoil electron. A concept of the Diamond Compton Telescope (DCT) consists of position sensitive layers of diamond-striped detector and calorimeter layer of CdTe detector. The key part of the DCT is diamond-striped detectors with a higher positional resolution and a wider energy range from 10 keV to 10 MeV. However, the diamond-striped detector is under development. We describe the performance of prototype diamond detector and the design of a possible DCT evaluated by Monte Carlo simulations.

Kinya Hibino; Toshisuke Kashiwagi; Shoji Okuno; Kaori Yajima; Yukio Uchihori; Hisashi Kitamura; Takeshi Takashima; Mamoru Yokota; Kenji Yoshida

2007-07-23

363

First coincidences in pre-clinical Compton camera prototype for medical imaging  

NASA Astrophysics Data System (ADS)

Compton collimated imaging may improve the detection of gamma rays emitted by radioisotopes used in single photon emission computed tomography (SPECT). We present a crude prototype consisting of a single 500?m thick, 256 pad silicon detector with pad size of 1.4×1.4mm2, combined with a 15×15×1cm3 NaI scintillator crystal coupled to a set of 20 photo multipliers. Emphasis is placed on the performance of the silicon detector and the associated read-out electronics, which has so far proved to be the most challenging part of the set-up. Results were obtained using the VATAGP3, 128 channel low-noise self-triggering ASIC as the silicon detector's front-end. The noise distribution (?) of the spectroscopic outputs gave an equivalent noise charge (ENC) with a mean value of =137e with a spread of 10e, corresponding to an energy resolution of 1.15keV FWHM for the scattered electron energy. Threshold settings above 8.2keV were required for stable operation of the trigger. Coincident Compton scatter events in both modules were observed for photons emitted by 57Co source with principal gamma ray energies of 122 and 136keV.

Studen, A.; Burdette, D.; Chesi, E.; Cindro, V.; Clinthorne, N. H.; Dulinski, W.; Fuster, J.; Han, L.; Kagan, H.; Lacasta, C.; Llosá, G.; Marques, A. C.; Malakhov, N.; Meier, D.; Mikuž, M.; Park, S. J.; Roe, S.; Rogers, W. L.; Steinberg, J.; Weilhammer, P.; Wilderman, S. J.; Zhang, L.; Žontar, D.

2004-09-01

364

Bulk Compton motion in the luminous quasar 4C04.42?  

E-print Network

We present the broadband analysis of the powerful quasar 4C04.42 (z=0.965) observed by XMM and INTEGRAL. The 0.2--200 keV spectrum is well reproduced with a hard power-law component ($\\Gamma\\sim$1.2), augmented by a soft component below 2 keV (observer frame), which is described by a thermal blackbody with temperature kT$\\backsimeq$ 0.15 keV. Alternatively, a broken power-law with E$_{break}$=2 keV and $\\Delta\\Gamma$=0.4 can equally well describe the data. Using archival data we compile the not-simultaneous Spectral Energy Distribution of the source from radio to gamma-ray frequencies. The SED shows two main components: the low frequency one produced by Synchrotron radiation from the electrons moving in the jet and the high energy one produced through external Compton scattering of the electrons with the photon field of the Broad Line Region. Within this scenario the excess emission in the soft-X ray band can be interpreted as due to Bulk Compton radiation of cold electrons. However, some other processes, bri...

De Rosa, A; Ubertini, P; Malizia, A; Dean, A J

2008-01-01

365

Prototype of hand-held Compton spectrometer for the spectrometric and dosimetric control of X-ray generators  

NASA Astrophysics Data System (ADS)

The Compton spectrometer is a device in which radiation coming from an X-ray generator is scattered at a known angle in order to reduce the flux and to allow spectrometric measurements without saturating the detector. A small-size prototype Compton spectrometer usable in the range 20-150 keV was developed, using a pen-type NaI detector. The source spectrum is reconstructed by unfolding the measured spectrum, using the response matrix calculated by the Monte-Carlo method. The Monte-Carlo geometrical model was validated with gamma-ray point sources. Unfolding is performed using a modified version of the GRAVEL algorithm. Results are presented for the unfolded spectrum obtained with a test measurement on a medical X-ray device.

Marwaha, Lara; Tondeur, François; Baré, Jonathan; Gerardy, Isabelle

2014-11-01

366

Introduction and recent developments in gamma-gamma, gamma-electron colliders  

E-print Network

High energy photon colliders (gamma-gamma, gamma-electron) based on backward Compton scattering of laser light is a very natural addition to e+e- linear colliders. In this report we consider mainly this option for the TESLA project. Recent study has shown that the horizontal emittance in the TESLA damping ring can be further decreased by a factor of four. In this case the gamma-gamma luminosity luminosity in the high energy part of spectrum can reach 0.3--0.5 L_e+e-. Typical cross sections of interesting processes in gamma-gamma collisions are higher than those in e+e- collisions by about one order of magnitude, so the number of events in gamma-gamma collisions will be more that in e+e- collisions. The key new element in photon colliders is a very powerful laser system. The most straightforward solution is ``an optical storage ring (optical trap)'' with diode pumped laser injector which is today technically feasible. This paper briefly review the status of a photon collider based at TESLA, its possible parameters.

Valery Telnov

2000-10-14

367

Analysis of a proposed Compton backscatter imaging technique  

SciTech Connect

Imaging techniques which require access to only one side of the object being viewed are potentially useful in situations where conventional projection radiography and tomography cannot be applied, such as looking for voids in a large container where access to the back of the object is inconvenient or even impossible. One-sided imaging techniques are currently being used in nondestructive evaluation of surfaces and shallow subsurface structures. In this work we present both analytical calculations and detailed Monte Carlo simulations aimed at assessing the capability of a proposed Compton backscatter imaging technique designed to detect and characterize voids located several centimeters below the surface of a solid. The proposed technique, based on a scheme suggested by Farmer and Collins, encodes the spatial position and structure of voids in a solid in the energy spectrum of the Compton-scattered photons as recorded by a high resolution detector. Our calculations model a {sup 137}Cs source projecting a 1 mm{sup 2} pencil beam of 662 keV gammas into a target slab at an incident angle of 45{degrees} and a collimated detector (also oriented at 45{degrees} with respect to the surface) which views the beam path at a central angle of 90{degrees}. The detector collimator is modeled here as a triangular slit viewing a 2.54 cm (1.000``) segment of the beam path at a depth of 2 cm below the surface of the slab. Our results suggest that the proposed technique should be capable of an absolute position resolution of {approx} 0.25 mm ({approx} 0.010``) for isolated voids and an overall object resolution of {approx} 1.00 Ip/mm ({approx} 0.04``). The predicted signal contrast for voids packed with various contraband materials will be discussed as well as multiple scattering contributions to the predicted yields.

Hall, J.; Jacoby, B.

1992-12-01

368

A position sensitive gamma-ray detector based on silicon drift detectors coupled to scintillators for application in the MEGA Compton telescope  

Microsoft Academic Search

An array of gamma-ray detectors based on silicon drift detectors (SDD) coupled to thallium activated cesium iodide (CsI(Tl)) scintillating crystals is presented. Because of SDDs low output capacitance and the possibility to have the first amplifying stage directly integrated on chip, SDDs show better noise performance than traditional p-i-n photodiodes. The array is read out with custom made ASICs built

M. Marisaldi; C. Labanti; A. Bulgarelli; A. Andritschke; G. Di Cocco; G. Kanbach; F. Gianotti; A. Mauri; E. Rossi; A. Traci; M. Trifoglio

2004-01-01

369

Geant4 Model Validation of Compton Suppressed System for Process monitoring of Spent Fuel  

SciTech Connect

Nuclear material accountancy is of continuous concern for the regulatory, safeguards, and verification communities. In particular, spent nuclear fuel reprocessing facilities pose one of the most difficult accountancy challenges: monitoring highly radioactive, fluid sample streams in near real-time. The Multi-Isotope Process monitor will allow for near-real-time indication of process alterations using passive gamma-ray detection coupled with multivariate analysis techniques to guard against potential material diversion or to enhance domestic process monitoring. The Compton continuum from the dominant 661.7 keV 137Cs fission product peak obscures lower energy lines which could be used for spectral and multivariate analysis. Compton suppression may be able to mitigate the challenges posed by the high continuum caused by scattering. A Monte Carlo simulation using the Geant4 toolkit is being developed to predict the expected suppressed spectrum from spent fuel samples to estimate the reduction in the Compton continuum. Despite the lack of timing information between decay events in the particle management of Geant4, encouraging results were recorded utilizing only the information within individual decays without accounting for accidental coincidences. The model has been validated with single and cascade decay emitters in two steps: as an unsuppressed system and with suppression activated. Results of the Geant4 model validation will be presented.

Bender, Sarah; Unlu, Kenan; Orton, Christopher R.; Schwantes, Jon M.

2013-05-01

370

Cosmic ray-dark matter scattering: a new signature of (asymmetric) dark matter in the gamma ray sky  

SciTech Connect

We consider the process of scattering of Galactic cosmic-ray electrons and protons off of dark matter with the radiation of a final-state photon. This process provides a novel way to search for Galactic dark matter with gamma rays. We argue that for a generic weakly interacting massive particle, barring effects such as co-annihilation or a velocity-dependent cross section, the gamma-ray emission from cosmic-ray scattering off of dark matter is typically smaller than that from dark matter pair-annihilation. However, if dark matter particles cannot pair-annihilate, as is the case for example in asymmetric dark matter scenarios, cosmic-ray scattering with final state photon emission provides a unique window to detect a signal from dark matter with gamma rays. We estimate the expected flux level and its spectral features for a generic supersymmetric setup, and we also discuss dipolar and luminous dark matter. We show that in some cases the gamma-ray emission might be large enough to be detectable with the Fermi Large Area Telescope.

Profumo, Stefano; Ubaldi, Lorenzo, E-mail: profumo@scipp.ucsc.edu, E-mail: ubaldi@physics.ucsc.edu [Department of Physics, University of California, 1156 High St., Santa Cruz, CA 95064 (United States)

2011-08-01

371

Bin mode estimation methods for Compton camera imaging  

NASA Astrophysics Data System (ADS)

We study the image reconstruction problem of a Compton camera which consists of semiconductor detectors. The image reconstruction is formulated as a statistical estimation problem. We employ a bin-mode estimation (BME) and extend an existing framework to a Compton camera with multiple scatterers and absorbers. Two estimation algorithms are proposed: an accelerated EM algorithm for the maximum likelihood estimation (MLE) and a modified EM algorithm for the maximum a posteriori (MAP) estimation. Numerical simulations demonstrate the potential of the proposed methods.

Ikeda, S.; Odaka, H.; Uemura, M.; Takahashi, T.; Watanabe, S.; Takeda, S.

2014-10-01

372

Fermi gamma-ray imaging of a radio galaxy.  

PubMed

The Fermi Gamma-ray Space Telescope has detected the gamma-ray glow emanating from the giant radio lobes of the radio galaxy Centaurus A. The resolved gamma-ray image shows the lobes clearly separated from the central active source. In contrast to all other active galaxies detected so far in high-energy gamma-rays, the lobe flux constitutes a considerable portion (greater than one-half) of the total source emission. The gamma-ray emission from the lobes is interpreted as inverse Compton-scattered relic radiation from the cosmic microwave background, with additional contribution at higher energies from the infrared-to-optical extragalactic background light. These measurements provide gamma-ray constraints on the magnetic field and particle energy content in radio galaxy lobes, as well as a promising method to probe the cosmic relic photon fields. PMID:20360067

Abdo, A A; Ackermann, M; Ajello, M; Atwood, W B; Baldini, L; Ballet, J; Barbiellini, G; Bastieri, D; Baughman, B M; Bechtol, K; Bellazzini, R; Berenji, B; Blandford, R D; Bloom, E D; Bonamente, E; Borgland, A W; Bregeon, J; Brez, A; Brigida, M; Bruel, P; Burnett, T H; Buson, S; Caliandro, G A; Cameron, R A; Caraveo, P A; Casandjian, J M; Cavazzuti, E; Cecchi, C; Celik, O; Chekhtman, A; Cheung, C C; Chiang, J; Ciprini, S; Claus, R; Cohen-Tanugi, J; Colafrancesco, S; Cominsky, L R; Conrad, J; Costamante, L; Cutini, S; Davis, D S; Dermer, C D; de Angelis, A; de Palma, F; Digel, S W; do Couto e Silva, E; Drell, P S; Dubois, R; Dumora, D; Farnier, C; Favuzzi, C; Fegan, S J; Finke, J; Focke, W B; Fortin, P; Fukazawa, Y; Funk, S; Fusco, P; Gargano, F; Gasparrini, D; Gehrels, N; Georganopoulos, M; Germani, S; Giebels, B; Giglietto, N; Giordano, F; Giroletti, M; Glanzman, T; Godfrey, G; Grenier, I A; Grove, J E; Guillemot, L; Guiriec, S; Hanabata, Y; Harding, A K; Hayashida, M; Hays, E; Hughes, R E; Jackson, M S; Jóhannesson, G; Johnson, A S; Johnson, T J; Johnson, W N; Kamae, T; Katagiri, H; Kataoka, J; Kawai, N; Kerr, M; Knödlseder, J; Kocian, M L; Kuss, M; Lande, J; Latronico, L; Lemoine-Goumard, M; Longo, F; Loparco, F; Lott, B; Lovellette, M N; Lubrano, P; Madejski, G M; Makeev, A; Mazziotta, M N; McConville, W; McEnery, J E; Meurer, C; Michelson, P F; Mitthumsiri, W; Mizuno, T; Moiseev, A A; Monte, C; Monzani, M E; Morselli, A; Moskalenko, I V; Murgia, S; Nolan, P L; Norris, J P; Nuss, E; Ohsugi, T; Omodei, N; Orlando, E; Ormes, J F; Paneque, D; Parent, D; Pelassa, V; Pepe, M; Pesce-Rollins, M; Piron, F; Porter, T A; Rainò, S; Rando, R; Razzano, M; Razzaque, S; Reimer, A; Reimer, O; Reposeur, T; Ritz, S; Rochester, L S; Rodriguez, A Y; Romani, R W; Roth, M; Ryde, F; Sadrozinski, H F-W; Sambruna, R; Sanchez, D; Sander, A; Saz Parkinson, P M; Scargle, J D; Sgrò, C; Siskind, E J; Smith, D A; Smith, P D; Spandre, G; Spinelli, P; Starck, J-L; Stawarz, ?; Strickman, M S; Suson, D J; Tajima, H; Takahashi, H; Takahashi, T; Tanaka, T; Thayer, J B; Thayer, J G; Thompson, D J; Tibaldo, L; Torres, D F; Tosti, G; Tramacere, A; Uchiyama, Y; Usher, T L; Vasileiou, V; Vilchez, N; Vitale, V; Waite, A P; Wallace, E; Wang, P; Winer, B L; Wood, K S; Ylinen, T; Ziegler, M; Hardcastle, M J; Kazanas, D

2010-05-01

373

Performance of a new electron-tracking Compton camera under intense radiations from a water target irradiated with a proton beam  

E-print Network

We have developed an electron-tracking Compton camera (ETCC) for use in next-generation MeV gamma ray telescopes. An ETCC consists of a gaseous time projection chamber (TPC) and pixel scintillator arrays (PSAs). Since the TPC measures the three dimensional tracks of Compton-recoil electrons, the ETCC can completely reconstruct the incident gamma rays. Moreover, the ETCC demonstrates efficient background rejection power in Compton-kinematics tests, identifies particle from the energy deposit rate (dE/dX) registered in the TPC, and provides high quality imaging by completely reconstructing the Compton scattering process. We are planning the "Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment" (SMILE) for our proposed all-sky survey satellite. Performance tests of a mid-sized 30 cm-cubic ETCC, constructed for observing the Crab nebula, are ongoing. However, observations at balloon altitudes or satellite orbits are obstructed by radiation background from the atmosphere and the detector itself. The background rejection power was checked using proton accelerator experiments conducted at the Research Center for Nuclear Physics, Osaka University. To create the intense radiation fields encountered in space, which comprise gamma rays, neutrons, protons, and other energetic entities, we irradiated a water target with a 140 MeV proton beam and placed a SMILE-II ETCC near the target. In this situation, the counting rate was five times than that expected at the balloon altitude. Nonetheless, the ETCC stably operated and identified particles sufficiently to obtain a clear gamma ray image of the checking source. Here, we report the performance of our detector and demonstrate its effective background rejection based in electron tracking experiments.

Yoshihiro Matsuoka; T. Tanimori; H. Kubo; A. Takada; J. D. Parker; T. Mizumoto; Y. Mizumura; S. Iwaki; T. Sawano; S. Komura; T. Kishimoto; M. Oda; T. Takemura; S. Miyamoto; S. Sonoda; D. Tomono; K. Miuchi; S. Kabuki; S. Kurosawa

2015-01-22

374

Performance of a new electron-tracking Compton camera under intense radiations from a water target irradiated with a proton beam  

E-print Network

We have developed an electron-tracking Compton camera (ETCC) for use in next-generation MeV gamma ray telescopes. An ETCC consists of a gaseous time projection chamber (TPC) and pixel scintillator arrays (PSAs). Since the TPC measures the three dimensional tracks of Compton-recoil electrons, the ETCC can completely reconstruct the incident gamma rays. Moreover, the ETCC demonstrates efficient background rejection power in Compton-kinematics tests, identifies particle from the energy deposit rate (dE/dX) registered in the TPC, and provides high quality imaging by completely reconstructing the Compton scattering process. We are planning the "Sub-MeV gamma ray Imaging Loaded-on-balloon Experiment" (SMILE) for our proposed all-sky survey satellite. Performance tests of a mid-sized 30 cm-cubic ETCC, constructed for observing the Crab nebula, are ongoing. However, observations at balloon altitudes or satellite orbits are obstructed by radiation background from the atmosphere and the detector itself. The background rejection power was checked using proton accelerator experiments conducted at the Research Center for Nuclear Physics, Osaka University. To create the intense radiation fields encountered in space, which comprise gamma rays, neutrons, protons, and other energetic entities, we irradiated a water target with a 140 MeV proton beam and placed a SMILE-II ETCC near the target. In this situation, the counting rate was five times than that expected at the balloon altitude. Nonetheless, the ETCC stably operated and identified particles sufficiently to obtain a clear gamma ray image of the checking source. Here, we report the performance of our detector and demonstrate its effective background rejection based in electron tracking experiments.

Yatsuoka Matsuoka; T. Tanimori; H. Kubo; A. Takada; J. D. Parker; T. Mizumoto; Y. Mizumura; S. Iwaki; T. Sawano; S. Komura; T. Kishimoto; M. Oda; T. Takemura; S. Miyamoto; S. Sonoda; D. Tomono; K. Miuchi; S. Kabuki; S. Kurosawa

2014-12-12

375

The Timing of Electron Beam Signatures in Hard X-Ray and Radio: Solar Flare Observations by BATSE/Compton Gamma-Ray Observatory and PHOENIX  

NASA Astrophysics Data System (ADS)

We analyzed two solar flares of 1992 September 5 and 6, using the high time resolution (64 ms) hard X-ray data from BATSE/CGRO, and 100-3000 MHz radio (100 ms) dynamic spectra from PHOENIX. The broadband radio data reveal a separatrix frequency (at 620 and 750 MHz in the two flares) between normal- and reverse-drifting radio bursts, indicating a compact acceleration source where electron beams are injected in both the upward and downward direction. We find a mean injection rate of 1.2 bursts s-1 in one flare and more than 0.7 bursts s-1 in the other. From 12 broad-band, reverse-drifting radio bursts we find in five cases an unambiguous one-to-one correlation between the reverse-drifting radio bursts and hard X-ray (HXR) pulses of similar duration (400±220 ms). The high significance (15±6 ?) of the HXR pulses and the small scatter (±150 ms) in the relative timing strongly supports a close causal connection. The cross-correlation between HXR and radio pulses shows that the HXR pulses are coincident (within the instrumental time resolution) with the reverse-drifting bursts at the injection frequency (880±50 MHz), and lead the radio bursts by 270±150 ms at the highest observable frequency (1240±100 MHz). The average drift time of the downward propagating radio bursts is measured to 150 ms, corresponding to a drift rate of 2350 MHz s-1. We examined various effects to model the observed timing of radio and HXR pulses (propagation delays, radio wave growth and damping, group velocity delays, radio wave scattering, radio wave ducting, light path differences, etc.). Assuming an exciter velocity of ?R/c = 0.2±0.1 for the reverse-drifting radio bursts, we infer an altitude difference of H = 8000±3000 km between the injection site and the HXR source. The most likely explanation for the retarded radio emission seems to be a combination of the following two effects: (1) HXR-emitting (>25 keV) and radio-emitting electrons have different energies (the exciter velocity of the reverse-drifting radio bursts is associated with ?5 keV electrons), and (2) a low (marginal) growth rate for plasma emission at the second harmonics. Delay effects caused by group velocity, collisional damping, wave scattering, and wave ducting are found to be minor (<30 ms each).

Aschwanden, Markus J.; Benz, Arnold O.; Schwartz, Richard A.

1993-11-01

376

Ultra-high brilliance multi-MeV $\\gamma$-ray beam from non-linear Thomson scattering  

E-print Network

We report on the generation of a narrow divergence ($\\theta\\approx 2.5$ mrad), multi-MeV ($E_\\text{MAX} = 18$ MeV) and ultra-high brilliance ($\\approx 2\\times10^{19}$ photons s$^{-1}$ mm$^{-2}$ mrad $^{-2}$ 0.1\\% BW) $\\gamma$-ray beam from the scattering of an ultra-relativistic laser-wakefield accelerated electron beam in the field of a relativistically intense laser (dimensionless amplitude $a_0\\approx2$). The spectrum of the generated $\\gamma$-ray beam is measured, with MeV resolution, seamlessly from 6 MeV to 18 MeV, giving clear evidence of the onset of non-linear Thomson scattering. The photon source has the highest brilliance in the multi-MeV regime ever reported in the literature.

Sarri, G; Schumaker, W; Cole, J; Di Piazza, A; Ahmed, H; Harvey, C; Keitel, C H; Krushelnick, K; Mangles, S P D; Najmudin, Z; Symes, D; Thomas, A G R; Yeung, M; Zhao, Z; Zepf, M

2014-01-01

377

The Compton effect: Transition to quantum mechanics  

NASA Astrophysics Data System (ADS)

The discovery of the Compton effect at the end of 1922 was a decisive event in the transition to the new quantum mechanics of 1925-1926 because it stimulated physicists to examine anew the fundamental problem of the interaction between radiation and matter. I first discuss Albert Einstein's light-quantum hypothesis of 1905 and why physicists greeted it with extreme skepticism, despite Robert A. Millikan's confirmation of Einstein's equation of the photoelectric effect in 1915. I then follow in some detail the experimental and theoretical research program that Arthur Holly Compton pursued between 1916 and 1922 at the University of Minnesota, the Westinghouse Lamp Company, the Cavendish Laboratory, and Washington University that culminated in his discovery of the Compton effect. Surprisingly, Compton was not influenced directly by Einstein's light-quantum hypothesis, in contrast to Peter Debye and H.A. Kramers, who discovered the quantum theory of scattering independently. I close by discussing the most significant response to that discovery, the Bohr-Kramers-Slater theory of 1924, its experimental refutation, and its influence on the emerging new quantum mechanics.

Stuewer, R. H.

2000-11-01

378

Filtered backprojection reconstruction and redundancy in Compton camera imaging.  

PubMed

During the acquisition process with the Compton gamma-camera, integrals of the intensity distribution of the source on conical surfaces are measured. They represent the Compton projections of the intensity. The inversion of the Compton transform reposes on a particular Fourier-Slice theorem. This paper proposes a filtered backprojection algorithm for image reconstruction from planar Compton camera data. We show how different projections are related together and how they may be combined in the tomographical reconstruction step. Considering a simulated Compton imaging system, we conclude that the proposed method yields accurate reconstructed images for simple sources. An elongation of the source in the direction orthogonal to the camera may be observed and is to be related to the truncation of the projections induced by the finite extent of the device. This phenomenon was previously observed with other reconstruction methods, e.g., iterative maximum likelihood expectation maximization. The redundancy of the Compton transform is thus an important feature for the reduction of noise in Compton images, since the ideal assumptions of infinite width and observation time are never met in practice. We show that a selection operated on the set of data allows to partially get around projection truncation, at the expense of an enhancement of the noise in the images. PMID:24196864

Maxim, Voichi?a

2014-01-01

379

Inclusive and Exclusive Compton Processes in Quantum Chromodynamics  

SciTech Connect

In our work, we describe two types of Compton processes. As an example of an inclusive process, we consider the high-energy photoproduction of massive muon pairs off the nucleon. We analyze the process in the framework of the QCD parton model, in which the usual parton distributions emerge as a tool to describe the nucleon in terms of quark and gluonic degrees of freedom. To study its exclusive version, a new class of phenomenological functions is required, namely, generalized parton distributions. They can be considered as a generalization of the usual parton distributions measured in deeply inelastic lepton-nucleon scattering. Generalized parton distributions (GPDs) may be observed in hard exclusive reactions such as deeply virtual Compton scattering. We develop an extension of this particular process into the weak interaction sector. We also investigate a possible application of the GPD formalism to wide-angle real Compton scattering.

Ales Psaker

2005-12-31

380

Compton Thick AGN  

NASA Astrophysics Data System (ADS)

Compton thick active galactic nuclei (AGN), which are obscured by column density NH > 1.5 × 104 cm-2, can be difficult to identify. They are certainly cosmically significant, both in producing the observed cosmic X-ray background, and in providing a location where black hole growth is hidden from view. Here I review some recent results from surveys that provide indications of Compton thick AGN, considering X-ray, radio, and infrared selection techniques. I also offer a caution against using mid-infrared silicate features to measure line-of-sight obscuration to active galactic nuclei. Instead, these features better indicate the geometric distribution of dust that the central engine heats. I conclude that the outstanding problem of Compton thick AGN is not the cases where the obscuration is directly associated with the environment of the active nucleus itself, even in the most obscured examples. Instead, we still risk missing the completely buried AGN, which are obscured by large amounts of gas and dust over large solid angles. The solution to finding Compton thick AGN may be to begin the search based on infrared emission and star formation, and then select for nuclear activity.

Levenson, N. A.

2014-07-01

381

Developing a Compton Polarimeter to Measure Polarization of Hard X-Rays in the 50-300 keV Energy Range  

E-print Network

This paper discusses the latest progress in the development of GRAPE (Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The purpose of GRAPE is to measure the polarization of hard X-rays in the 50-300 keV energy range. We are particularly interested in X-rays that are emitted from solar flares and gamma-ray bursts (GRBs). Accurately measuring the polarization of the emitted radiation from these sources will lead, to a better understating of both the emission mechanisms and source geometries. The GRAPE design consists of an array of plastic scintillators surrounding a central high-Z crystal scintillator. We can monitor individual Compton scatters that occur in the plastics and determine whether the photon is photo absorbed by the high-Z crystal or not. A Compton scattered photon that is immediately photo absorbed by the high-Z crystal constitutes a valid event. These valid events provide us with the interaction locations of each incident photon and ultimately produces a modulation pattern for the Compton scattering of the polarized radiation. Comparing with Monte Carlo simulations of a 100% polarized beam, the level of polarization of the measured beam can then be determined. The complete array is mounted on a flat-panel multi-anode photomultiplier tube (MAPMT) that can measure the deposited energies resulting from the photon interactions. The design of the detector allows for a large field-of-view (>pi steradian), at the same time offering the ability to be close-packed with multiple modules in order to reduce deadspace. We plan to present in this paper the latest laboratory results obtained from GRAPE using partially polarized radiation sources.

J. S. Legere; P. Bloser; J. R. Macri; M. L. McConnell; T. Narita; J. M. Ryan

2005-08-14

382

Determination of boron in water using neutron scattering and transmission, and prompt gamma ray neutron activation analysis methods: A comparative study  

NASA Astrophysics Data System (ADS)

The boron concentration in water was determined using neutron scattering and transmission, and prompt gamma ray neutron activation analysis methods. The experimental setup is based on a Pu-Be neutron source, 3He neutron detectors and an NaI(Tl) gamma-ray detector. Water samples of different volumes and known amounts of boron were prepared. Transmitted and scattered neutrons and prompt gamma rays resulting from neutron capture reactions within the samples were simultaneously measured. The sensitivities of the neutron scattering and transmission measurements were determined to be better than those of the prompt gamma ray neutron activation analysis. The neutron scattering measurements were determined to be more sensitive than those of the neutron transmission measurements.

El Abd, A.

2014-10-01

383

Gamma ray production cross section from energetic neutron inelastic scattering for methodical improvements in planetary gamma-ray spectroscopy  

SciTech Connect

Planetary Gamma ray spectroscopy can be used to chemically analyze the top soil from planets in future planetary missions. The production from inelastic neutron interaction plays an effective role in the determination on the C and H at the surface. The gamma ray production cross section from the strongest lines excited in the neutron bombardment of Fe have been measured by the use of a time analyzed quasi-mono-energetic neutron beam and a high purity germanium detector. The results from En=6.5, 32, 43, and 65 MeV are presented.

Castaneda, C.M.; Gearhart, R.; Sanii, B. (California Univ., Davis, CA (United States). Crocker Nuclear Lab.); Englert, P.A.J. (San Jose State Univ., CA (United States)); Drake, D.M.; Reedy, R.C. (Los Alamos National Lab., NM (United States))

1991-01-01

384

Gamma ray production cross section from energetic neutron inelastic scattering for methodical improvements in planetary gamma-ray spectroscopy  

SciTech Connect

Planetary Gamma ray spectroscopy can be used to chemically analyze the top soil from planets in future planetary missions. The production from inelastic neutron interaction plays an effective role in the determination on the C and H at the surface. The gamma ray production cross section from the strongest lines excited in the neutron bombardment of Fe have been measured by the use of a time analyzed quasi-mono-energetic neutron beam and a high purity germanium detector. The results from En=6.5, 32, 43, and 65 MeV are presented.

Castaneda, C.M.; Gearhart, R.; Sanii, B. [California Univ., Davis, CA (United States). Crocker Nuclear Lab.; Englert, P.A.J. [San Jose State Univ., CA (United States); Drake, D.M.; Reedy, R.C. [Los Alamos National Lab., NM (United States)

1991-12-31

385

PLEIADES: a Picosecond, High Peak Brightness Compton Scattering X-Ray Source for Advanced Backlighting and Time-Resolved Material Studies  

NASA Astrophysics Data System (ADS)

In January 2003, the PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility produced first light at 70 keV. This important milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as NIF diagnostics and time-resolved material studies. Initial x-rays were captured with a cooled CCD using a Cesium Iodide scintillator; the photon energy was measured at approximately 70 keV, and the observed angular distribution found to agree very well with three-dimensional codes. The electron beam was focused to 80 mm rms, at 54 MeV, with 250 pC of charge, a relative energy spread of 0.2%, and a normalized emittance of 10 mm.mrad. Optimization of the x-ray dose is currently underway, with the goal of reaching 10^8 photons per shot and a peak brightness approaching 10^20 photons / mm^2 / mrad^2 / s / 0.1% bandwidth, which would represent a world-record brightness at this x-ray energy and pulse duration. Nonlinear scattering experiments, using a tightly focused laser spot will also be discussed, as well as plans to develop a source capable of reaching 1% conversion efficiency from the electron beam kinetic energy into x-rays.

Fittinghoff, David

2003-10-01

386

Diffuse Galactic low energy gamma ray continuum emission  

NASA Technical Reports Server (NTRS)

We investigate the origin of diffuse low-energy Galactic gamma-ray continuum down to about 30 keV. We calculate gamma-ray emission via bremsstrahlung and inverse Compton scattering by propagating an unbroken electron power law injection spectrum and employing a Galactic emmissivity model derived from COSB observations. To maintain the low energy electron population capable of producing the observed continuum via bremsstrahlung, a total power input of 4 x 10 exp 41 erg/s is required. This exceeds the total power supplied to the nuclear cosmic rays by about an order of magnitude.

Skibo, J. G.; Ramaty, R.

1993-01-01

387

Precision linac and laser technologies for nuclear photonics gamma-ray sources  

SciTech Connect

Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scattered and Doppler upshifted by a high brightness electron beam to generate tunable and highly collimated gamma-ray pulses. The electron and laser beam parameters can be optimized to achieve the spectral brightness and narrow bandwidth required by nuclear photonics applications. A description of the design of the next generation precision gamma-ray source currently under construction at Lawrence Livermore National Laboratory is presented, along with the underlying motivations. Within this context, high-gradient X-band technology, used in conjunction with fiber-based photocathode drive laser and diode pumped solid-state interaction laser technologies, will be shown to offer optimal performance for high gamma-ray spectral flux, narrow bandwidth applications.

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

2012-05-15

388

Synchro-self-compton Radiation Mechanism Of Jets Of AGN With Ultra And Moderate Relativistic Electrons  

Microsoft Academic Search

New expressions are obtained for intensity of radiation of moderate relativistic electrons in a weak magnetic field. For ultrarelativistic electrons these expressions transform to well known formulae. With obtained earlier formulae for Compton scattering for arbitrary electron and photon energies the complete description of synchro-self-Compton radiation mechanism is given. Corresponding computer codes for calculation are written. The results can be

D. Nagirner

2011-01-01

389

High Energy Gamma-Ray Emission From Blazars: EGRET Observations  

E-print Network

We will present a summary of the observations of blazars by the Energetic Gamma Ray Experiment Telescope (EGRET) on the Compton Gamma Ray Observatory (CGRO). EGRET has detected high energy gamma-ray emission at energies greater than 100 MeV from more that 50 blazars. These sources show inferred isotropic luminosities as large as $3\\times 10^{49}$ ergs s$^{-1}$. One of the most remarkable characteristics of the EGRET observations is that the gamma-ray luminosity often dominates the bolometric power of the blazar. A few of the blazars are seen to exhibit variability on very short time-scales of one day or less. The combination of high luminosities and time variations seen in the gamma-ray data indicate that gamma-rays are an important component of the relativistic jet thought to characterize blazars. Currently most models for blazars involve a beaming scenario. In leptonic models, where electrons are the primary accelerated particles, gamma-ray emission is believed to be due to inverse Compton scattering of low energy photons, although opinions differ as to the source of the soft photons. Hardronic models involve secondary production or photomeson production followed by pair cascades, and predict associated neutrino production.

R. Mukherjee

1999-01-17

390

OVERVIEW OF MONO-ENERGETIC GAMMA-RAY SOURCES & APPLICATIONS  

SciTech Connect

Recent progress in accelerator physics and laser technology have enabled the development of a new class of tunable 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 Mono-Energetic Gamma-ray (MEGa-ray) source driven by a compact, high-gradient X-band linac is currently under development and construction at LLNL. High-brightness, relativistic electron bunches produced by an X-band linac designed in collaboration with SLAC NAL will interact with a Joule-class, 10 ps, diode-pumped CPA laser pulse to generate tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range via Compton scattering. This MEGa-ray source will be used to excite nuclear resonance fluorescence 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, along with important applications, including nuclear resonance fluorescence. In conclusion, we have optimized the design of a high brightness Compton scattering gamma-ray source, specifically designed for NRF applications. Two different parameters sets have been considered: one where the number of photons scattered in a single shot reaches approximately 7.5 x 10{sup 8}, with a focal spot size around 8 {micro}m; in the second set, the spectral brightness is optimized by using a 20 {micro}m spot size, with 0.2% relative bandwidth.

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 P; Vlieks, A E; Jongewaard, E N; Tantawi, S G; Raubenheimer, T O

2010-05-18

391

Incoherent scattering of 59.54 keV gamma rays by selected elements in the atomic region 29<=Z<=74  

Microsoft Academic Search

Incoherent scattering cross-sections for 11 moderate to high atomic number elements have been experimentally determined using 59.54 keV gamma rays emitted by the radionuclide 241Am. Measurements were performed using a standard back-scattering geometry set up to obtain scattering angles of 145 deg, 154 deg and 165 deg. Resulting photon momentum transfers were in the range 4.58<=x<=4.76 Å-1. High purity (better

I. S. Elyaseery; A. Shukri; C. S. Chong; A. A. Tajuddin; D. A. Bradley

1999-01-01

392

Prompt Gamma-Ray Burst Spectra: Detailed Calculations and the Effect of Pair Production  

Microsoft Academic Search

We present detailed calculations of the prompt spectrum of gamma-ray bursts (GRBs) predicted within the fireball model framework, in which emission is due to internal shocks in an expanding relativistic wind. Our time-dependent numerical model describes cyclo-synchrotron emission and absorption, inverse and direct Compton scattering, and e+\\/- pair production and annihilation (including the evolution of high-energy electromagnetic cascades). It allows,

Asaf Pe'er; Eli Waxman

2004-01-01

393

Least-Squares Deconvolution of Compton Telescope Data with the Positivity Constraint  

NASA Technical Reports Server (NTRS)

We describe a Direct Linear Algebraic Deconvolution (DLAD) approach to imaging of data from Compton gamma-ray telescopes. Imposition of the additional physical constraint, that all components of the model be non-negative, has been found to have a powerful effect in stabilizing the results, giving spatial resolution at or near the instrumental limit. A companion paper (Dixon et al. 1993) presents preliminary images of the Crab Nebula region using data from COMPTEL on the Compton Gamma-Ray Observatory.

Wheaton, William A.; Dixon, David D.; Tumer, O. Tumay; Zych, Allen D.

1993-01-01

394

G. E. M. Jauncey and the Compton Effect  

NASA Astrophysics Data System (ADS)

In late 1922 Arthur Holly Compton (1892-1962) discovered that an X-ray quantum of radiation undergoes a discrete change in wavelength when it experiences a billiard-ball collision with a single atomic electron, a phenomenon that became known as the Compton effect and for which he shared the Nobel Prize in Physics for 1927. But for more than five years before he made his discovery, Compton had analyzed X-ray scattering in terms of classical electrodynamics. I suggest that his colleague at Washington University in St. Louis, G. E. M. Jauncey (1888-1947), helped materially to persuade him to embrace the quantum interpretation of his X-ray scattering experiments.

Jenkin, John

395

Giant Flare in SGR 1806-20 and Its Compton Reflection from the Moon  

E-print Network

We analyze the data obtained when the Konus-Wind gamma-ray spectrometer detected a giant flare in SGR 1806-20 on December 27, 2004. The flare is similar in appearance to the two known flares in SGR 0526-66 and SGR 1900+14 while exceeding them significantly in intensity. The enormous X-ray and gamma-ray flux in the narrow initial pulse of the flare leads to almost instantaneous deep saturation of the gamma-ray detectors, ruling out the possibility of directly measuring the intensity, time profile, and energy spectrum of the initial pulse. In this situation, the detection of an attenuated signal of Compton back-scattering of the initial pulse emission by the Moon with the Helicon gamma-ray spectrometer onboard the Coronas-F satellite was an extremely favorable circumstance. Analysis of this signal has yielded the most reliable temporal, energy, and spectral characteristics of the pulse. The temporal and spectral characteristics of the pulsating flare tail have been determined from Konus-Wind data. Its soft spectra have been found to contain also a hard power-law component extending to 10 MeV. A weak afterglow of SGR 1806-20 decaying over several hours is traceable up to 1 MeV. We also consider the overall picture of activity of SGR 1806-20 in the emission of recurrent bursts before and after the giant flare.

D. D. Frederiks; S. V. Golenetskii; V. D. Palshin; R. L. Aptekar; V. N. Ilyinskii; F. P. Oleinik; E. P. Mazets; T. L. Cline

2006-12-12

396

Dark matter multi-wavelength constraints from synchrotron and inverse compton radiation  

NASA Astrophysics Data System (ADS)

If coming from WIMP annihilation, the excess of electrons/positrons observed by the Pamela/ATIC/Fermi experiments gives rise to a noticeable amount of synchrotron and Inverse Compton Scattering (ICS) radiation around 10-100 GeV when the e+e- interact with the Galactic Magnetic Field, and the InterStellar Radiation Field (ISRF). Further, the Pamela/ATIC/Fermi excess can be tested through the shape of the ICS signal, which is expected to show a peculiar and clean “ICS Haze” feature. We discuss the constraints coming from radio observations, as well as the implications of some preliminary Fermi results on the diffuse gamma background in the inner galactic region.

Cuoco, A.

2011-02-01

397

A Compton camera application for the GAMOS GEANT4-based framework  

NASA Astrophysics Data System (ADS)

Compton camera systems can be used to image sources of gamma radiation in a variety of applications such as nuclear medicine, homeland security and nuclear decommissioning. To locate gamma-ray sources, a Compton camera employs electronic collimation, utilising Compton kinematics to reconstruct the paths of gamma rays which interact within the detectors. The main benefit of this technique is the ability to accurately identify and locate sources of gamma radiation within a wide field of view, vastly improving the efficiency and specificity over existing devices. Potential advantages of this imaging technique, along with advances in detector technology, have brought about a rapidly expanding area of research into the optimisation of Compton camera systems, which relies on significant input from Monte-Carlo simulations. In this paper, the functionality of a Compton camera application that has been integrated into GAMOS, the GEANT4-based Architecture for Medicine-Oriented Simulations, is described. The application simplifies the use of GEANT4 for Monte-Carlo investigations by employing a script based language and plug-in technology. To demonstrate the use of the Compton camera application, simulated data have been generated using the GAMOS application and acquired through experiment for a preliminary validation, using a Compton camera configured with double sided high purity germanium strip detectors. Energy spectra and reconstructed images for the data sets are presented.

Harkness, L. J.; Arce, P.; Judson, D. S.; Boston, A. J.; Boston, H. C.; Cresswell, J. R.; Dormand, J.; Jones, M.; Nolan, P. J.; Sampson, J. A.; Scraggs, D. P.; Sweeney, A.; Lazarus, I.; Simpson, J.

2012-04-01

398

Studies on sensitivity, resolution, and Doppler broadening in gamma-ray imaging with pixellated semiconductor detectors  

NASA Astrophysics Data System (ADS)

We studied the Doppler broadening effect which is one of the major issues pertaining to overall imaging quality in Compton cameras. For the study of Doppler broadening due to the pre-collision electron momentum, we used a collimated beam of 662-keV gamma rays and selected events corresponding to the 90° Compton scattering using a Compton spectrometer, consisting of a 25-fold segmented germanium detector and a coaxial germanium detector shielded with a bismuth germanate (BGO) scintillator. Comparison of the energy spread due to Doppler broadening between a silicon and a germanium detector was made with the Monte Carlo simulation. To see the effect of Doppler broadening on the image resolution, we performed the Monte Carlo simulation in a simple backprojection method.

Lee, J. H.; Lee, C. S.

2004-12-01

399

A resonance-fluorescence measurement of the lifetime of the 1.013 MeV level in ²?Al using Compton-scattered gamma rays  

E-print Network

:; 0"". ;. ;. i F V. l'i~ 'i:1. '! VR'-'"" 6-" 8 4 g / 5 Q3': 86 f: 4" ""'8 t:!" ~ %" '-" 8 Z ' '!'. :. ~', l (' -'&);; ", y ge & p g ja ~y-. g~~~)", $y P tt". "I i!J ':ii:itS S !" QSC ", '*O' "" OI ts'". PGt'I "t f f S!. S i C h ' CO ISDVCS SVO..., TtflS !, ', SO!! ':;:S'O tS! tV!'. ;StSt. lit ti. ?' S SOSSPt 1". a Ottp Of Chip f OV"" 100 C hl":VQSl S!O::i!op!It OS Of C I'. S !t!V 1 '-1 CI!S VSi81 S OS 1 ti ZS V. 'tQ S!t'CStt SVO'"t. t X'V!S ChP, " S!SiSS'!'! Ji C-; ' lt. '"SS:LOP Of f hO EV 1 I...

Peticolas, John Davis

1967-01-01

400

POLARIZED POSITRON SOURCE WITH A COMPTON MULTIPLE INTERACTION POINT LINE  

E-print Network

according to the elec- tron source used for the Compton scattering: linac based, storage ring based, a capture section based on an adiabatic matching device (AMD) followed by a pre-injector linac is simulated to capture the produced positrons and the pre-injector linac for primary acceleration. Then, the positron

Paris-Sud XI, Université de

401

Compton Polarimetry in Gamma-Ray Astronomy  

Microsoft Academic Search

The analysis of compact astronomical objects has generally dealt with the physical properties of the source within a two-parameter space, which is defined by the spectral characteristics and time variability. This approach often leads to the situation whereby two or more very different models can explain the observations successfully. Polarimetric observations have the diagnostic potential to discriminate between the different

F. Lei; A. J. Dean; G. L. Hills

1997-01-01

402

A cubic gamma camera with an active collimator.  

PubMed

Mechanical collimation with photon absorption and electronic collimation using Compton scattering are combined to form a cubic gamma camera with an active collimator. The collimator is made active by constructing it with a uniformly redundant array of patterned Bi4Ge3O12 (BGO) scintillators, which not only attenuates incident radiations but also detects scattered radiation, in a gamma-camera consisting of and five planar CsI(Na) scintillators. The entire module forms a cubic structure that generates images on the basis of radiation interactions from every direction. The coverage angle for detecting scattered radiation is 2? with a detection efficiency approximately 17 times higher than previous systems that comprised only one pair of detectors. PMID:24709608

Lee, Taewoong; Lee, Wonho

2014-08-01

403

Method and apparatus for measuring lung density by Compton backscattering  

DOEpatents

The density of the lung of a patient suffering from pulmonary edema is monitored by irradiating the lung by a single collimated beam of monochromatic photons and measuring the energies of photons compton back-scattered from the lung by a single high-resolution, high-purity germanium detector. A compact system geometry and a unique data extraction scheme are utilized to minimize systematic errors due to the presence of the chestwall and multiple scattering. 11 figs., 1 tab.

Loo, B.W.; Goulding, F.S.

1988-03-11

404

Compton profile study of ZrB2  

NASA Astrophysics Data System (ADS)

In this paper, we investigate the Compton profile of ZrB2. The theoretical Compton profile of ZrB2 is computed within the framework of density functional theory (DFT) based on linear combination of atomic orbitals (LCAO). To compare the spherically averaged theoretical values, the measurement on polycrystalline ZrB2 is performed using 59.54 keV gamma-rays emanating from an 241Am radioisotope. To estimate the charge transfer in ZrB2, ionic model based calculations have also been performed which suggest transfer of electron from Zr to B atoms.

Vyas, V.; Kumar, R.; Sharma, G.; Sharma, B. K.

2013-06-01

405

High-repetition intra-cavity source of Compton radiation  

NASA Astrophysics Data System (ADS)

We report our progress in developing a high-power Compton source for a diversity of applications ranging from university-scale compact x-ray light sources and metrology tools for EUV lithography, to high-brilliance gamma-sources for nuclear analysis. Our conceptual approach lies in multiplying the source’s repetition rate and increasing its average brightness by placing the Compton interaction point inside the optical cavity of an active laser. We discuss considerations in its design, our simulations, and tests of the laser’s cavity that confirm the feasibility of the proposed concept.

Pogorelsky, I.; Agustsson, R.; Campese, T.; Murokh, A.; Ovodenko, A.; Polyanskiy, M.; Shaftan, T.

2014-12-01

406

Picosecond Pulse Recirculation for High Average Brightness Thomson Scattering-based Gamma-ray Sources  

SciTech Connect

Pulse recirculation has been successfully demonstrated with the interaction laser system of LLNL's Thomson-Radiated Extreme X-ray (T-REX) source. The recirculation increased twenty-eight times the intensity of the light coming out of the laser system, demonstrating the capability of increasing the gamma-ray flux emitted by T-REX. The technical approach demonstrated could conceivably increase the average gamma-ray flux output by up to a hundred times.

Semenov, V

2009-05-28

407

Small Angle Neutron Scattering and Gamma-Ray Scattering for the Study of Second Phase Precipitation in Semiconductor Silicon and the Nimonic Superalloy PE16.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. The precipitation of oxygen in silicon has been investigated using SANS. A major investigation has been made using a heat treatment temperature of 750 ^circC. The measured cross-sections have been analysed using the Guinier approximation and the results linked with infrared measurements of the interstitial oxygen concentration in solid solution. Kinetic constants have been derived through a use of Ham's theory of diffusion limited precipitation (Ham (1958)). The diffusion coefficient of oxygen in silicon has been derived. Good correlation has been found between SANS and TEM measurements of precipitate dimensions. Further investigations have been made using samples heat treated at 450, 550, 650 and 850^ circC. The technique of gamma Ray diffraction has been used in an attempt to observe effects due to oxygen precipitation in silicon. Asymmetric diffuse scattering has been observed around Bragg peaks, as characteristic of interstitial type defects. Quantitative analysis of this scattering has lead to precipitate dimensions in reasonable agreement with that found by the analysis of SANS data. Changes in the integrated reflecting power have been found, both within the same sample and as a function of heat treatment temperature. These changes have been attributed to crystal defects as a result of crystal growth and precipitation. An initial investigation has been made on the combined effects of temperature and stress on the microstructure of a nickel based superalloy, the Nimonic Alloy PE16. The action of stress on top of temperature has been found to cause an increase in the size of gamma^ ' precipitates. A method has been developed for the extraction of size distribution functions from SANS data. Simulations have been performed to test the feasibility of this method, and gain experience for the use of experimental data. One set of real SANS data has also been used to extract a size distribution function.

Kinder, Stephen Hugh

408

Nuclear {gamma} resonance time-domain interferometry: Quantum beat and radiative coupling regimes compared in revealing quasielastic scattering  

SciTech Connect

Nuclear {gamma} resonance time-domain interferometry (TDI) is a method where the interference pattern is built in time during the delayed scattering of synchrotron radiation by a system composed of two nuclear resonant targets and a nonresonant sample placed in between. The radiation transmitted through the upstream target is scattered by the sample at a finite angle and is transmitted through the downstream target. Atomic motions in the sample perturbing the delayed radiation can be revealed directly in the time interference pattern. The unique sharpness of nuclear resonant scattering allows one to investigate atomic motions proceeding for times in the range of nanoseconds to microseconds. The radiative coupling (RC) regime of TDI where the radiation from the upstream nuclear target is in resonance with the downstream target was investigated experimentally and compared with the quantum beat (QB) regime where the resonances in the targets are well separated. Clear evolutions of the interference patterns were observed with glycerol as a sample in both regimes, manifesting the increase of quasielastic scattering both with increasing temperature and with momentum transfer. However, the increase of quasielastic scattering is revealed in quite different ways: in the QB regime through pronounced changes of the quantum beat modulation of a fixed interference pattern, in the RC regime via strong changes of the interference pattern itself, mainly of its dynamical beat structure. It was possible to find relaxation parameters by which the two sets of completely different time evolutions for the QB and RC regimes were consistently fitted. Such a treatment will in the future considerably enlarge the dynamic range of the method and increase the reliability of the data analysis.

Smirnov, G. V. [Russian Research Center 'Kurchatov Institute', 123182 Moscow (Russian Federation); Buerck, U. van; Petry, W. [Physik-Department, Technische Universitaet Muenchen, D-85748 Garching (Germany); Franz, H. [Hamburger Synchrotronstrahlungslabor, Deutsches Elektronen Synchrotron, D-22603 Hamburg (Germany); Asthalter, T. [Institut fuer Physikalische Chemie, Universitaet Stuttgart, D-70569 Stuttgart (Germany); Leupold, O.; Schreier, E. [European Synchrotron Radiation Facility, F-38043, Grenoble (France)

2006-05-01

409

POLAR: a new polarimeter for X and gamma rays  

NASA Astrophysics Data System (ADS)

We present a novel compact polarimeter instrument POLAR for polarization measurements in the energy range from hard X-rays to soft gamma rays It uses an array of fast low density scintillators and properties of the gamma-electron Compton scattering to determine polarization of the incoming photons The design consists of 2304 plastic scintillator bars with dimension of 6x6x200 mm 3 The instrument has a wide viewing angle third of the sky cover and is sensitive in the range from about ten to few hundred keV Its analyzing power and efficiency were optimized and modeled with Monte Carlo simulations Large active area and high efficiency for Compton scattering detection result in a particularly big figure of merit that combines analyzing power and the effective area of the detector Moreover such high values are kept also for gammas coming off the detector axis what makes POLAR especially attractive as a large field of view device that can be easily used for measurements from random sources like Gamma Ray Bursts Currently the laboratory tests are performed using smaller version of the instrument and polarized photon sources at different energies In the next step the detector prototype will be intensively calibrated with the polarized light from the PSI synchrotron source First verification in space will be performed using a balloon flight for background studies and observations of bright X-ray sources like CRAB

Suarez-Garcia, E.; Polar Team

410

HIGH-ENERGY EMISSION OF GRB 130427A: EVIDENCE FOR INVERSE COMPTON RADIATION  

SciTech Connect

A nearby superluminous burst GRB 130427A was simultaneously detected by six ?-ray space telescopes (Swift, the Fermi GLAST Burst Monitor (GBM)/Large Area Telescope, Konus-Wind, SPI-ACS/INTEGRAL, AGILE, and RHESSI) and by three RAPTOR full-sky persistent monitors. The isotropic ?-ray energy release is ?10{sup 54} erg, rendering it the most powerful explosion among gamma-ray bursts (GRBs) with a redshift z ? 0.5. The emission above 100 MeV lasted about one day, and four photons are at energies greater than 40 GeV. We show that the count rate of 100 MeV-100 GeV emission may be mainly accounted for by the forward shock synchrotron radiation and the inverse Compton radiation likely dominates at GeV-TeV energies. In particular, an inverse Compton radiation origin is favored for the ?(95.3, 47.3, 41.4, 38.5, 32) GeV photons arriving at t ? (243, 256.3, 610.6, 3409.8, 34366.2) s after the trigger of Fermi-GBM. Interestingly, the external inverse Compton scattering of the prompt emission (the second episode, i.e., t ? 120-260 s) by the forward-shock-accelerated electrons is expected to produce a few ?-rays at energies above 10 GeV, while five were detected in the same time interval. A possible unified model for the prompt soft ?-ray, optical, and GeV emission of GRB 130427A, GRB 080319B, and GRB 090902B is outlined. Implications of the null detection of >1 TeV neutrinos from GRB 130427A by IceCube are discussed.

Fan, Yi-Zhong; Zhang, Fu-Wen; He, Hao-Ning; Zhou, Bei; Yang, Rui-Zhi; Jin, Zhi-Ping; Wei, Da-Ming [Key Laboratory of Dark Matter and Space Astronomy, Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China); Tam, P. H. T. [Institute of Astronomy and Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan (China); Liang, Yun-Feng, E-mail: yzfan@pmo.ac.cn, E-mail: fwzhang@pmo.ac.cn, E-mail: dmwei@pmo.ac.cn [Department of Physics, Guangxi University, Guangxi 530004 (China)

2013-10-20

411

Proton scattering from an excited nucleus (18Fm,Jpi=5+,Ex=1.1 MeV) using a gamma-ray-tagged secondary isomeric nuclear beam  

Microsoft Academic Search

We have used gamma-ray tagging to identify a secondary isomeric beam of the short-lived, high-spin isomer 18Fm (Ex=1.1 MeV, Jpi=5+) produced at the K1200 cyclotron at the National Superconducting Cyclotron Laboratory. Elastic scattering of p+18Fm at Ec.m.~=20 MeV was observed using the characteristic gamma decays of 18Fm (T1\\/2=163 ns) to identify the state of the projectile after the scattering, thus

J. A. Brown; F. D. Becchetti; J. Jänecke; D. A. Roberts; D. W. Litzenberg; T. W. O'donnell; R. E. Warner; N. A. Orr; R. M. Ronningen

1995-01-01

412

Precision X-Band Linac Technologies for Nuclear Photonics Gamma-Ray Sources  

SciTech Connect

Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies. The nascent field of nuclear photonics is enabled by the recent maturation of new technologies, including high-gradient X-band electron acceleration, robust fiber laser systems, and hyper-dispersion CPA. Recent work has been performed at LLNL to demonstrate isotope-specific detection of shielded materials via NRF using a tunable, quasi-monochromatic Compton scattering gamma-ray source operating between 0.2 MeV and 0.9 MeV photon energy. This technique is called Fluorescence Imaging in the Nuclear Domain with Energetic Radiation (or FINDER). This work has, among other things, demonstrated the detection of {sup 7}Li shielded by Pb, utilizing gamma rays generated by a linac-driven, laser-based Compton scattering gamma-ray source developed at LLNL. Within this context, a new facility is currently under construction at LLNL, with the goal of generating tunable {gamma}-rays in the 0.5-2.5 MeV photon energy range, at a repetition rate of 120 Hz, and with a peak brightness in the 10{sup 20} photons/(s x mm{sup 2} x mrad{sup 2} x 0.1% bw).

Hartemann, F V; Albert, F; Anderson, S G; Bayramian, A J; Cross, R R; Ebbers, C A; Gibson, D J; Houck, T L; Marsh, R A; Messe