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Sample records for compton thick active

  1. An Iwasawa-Taniguchi Effect for Compton-thick Active Galactic Nuclei

    Science.gov (United States)

    Boorman, Peter G.; Gandhi, Poshak; Baloković, Mislav; Brightman, Murray; Harrison, Fiona; Ricci, Claudio; Stern, Daniel

    2018-04-01

    We present the first study of an Iwasawa-Taniguchi/`X-ray Baldwin' effect for Compton-thick active galactic nuclei (AGN). We report a statistically significant anti-correlation between the rest-frame equivalent width (EW) of the narrow core of the neutral Fe Kα fluorescence emission line, ubiquitously observed in the reflection spectra of obscured AGN, and the mid-infrared 12 μ m continuum luminosity (taken as a proxy for the bolometric AGN luminosity). Our sample consists of 72 Compton-thick AGN selected from pointed and deep-field observations covering a redshift range of z ˜ 0.0014 - 3.7. We employ a Monte Carlo-based fitting method, which returns a Spearman's Rank correlation coefficient of ρ = - 0.28 ± 0.12, significant to 98.7% confidence. The best fit found is log(EW_{Fe Kα }) ∝ -0.08± 0.04 log(L_{12 {μ } m}), which is consistent with multiple studies of the X-ray Baldwin effect for unobscured and mildly obscured AGN. This is an unexpected result, as the Fe Kα line is conventionally thought to originate from the same region as the underlying reflection continuum, which together constitute the reflection spectrum. We discuss the implications this could have if confirmed on larger samples, including a systematic underestimation of the line of sight X-ray obscuring column density and hence the intrinsic luminosities and growth rates for the most luminous AGN.

  2. Compton-thick AGN at high and low redshift

    Science.gov (United States)

    Akylas, A.; Georgantopoulos, I.; Corral, A.; Ranalli, P.; Lanzuisi, G.

    2017-10-01

    The most obscured sources detected in X-ray surveys, the Compton-thick AGN present great interest both because they represent the hidden side of accretion but also because they may signal the AGN birth. We analyse the NUSTAR observations from the serendipitous observations in order to study the Compton-thick AGN at the deepest possible ultra-hard band (>10 keV). We compare our results with our SWIFT/BAT findings in the local Universe, as well as with our results in the CDFS and COSMOS fields. We discuss the comparison with X-ray background synthesis models finding that a low fraction of Compton-thick sources (about 15 per cent of the obscured population) is compatible with both the 2-10keV band results and those at harder energies.

  3. Determining the Covering Factor of Compton-Thick Active Galactic Nuclei with NuSTAR

    Science.gov (United States)

    Brightman, M.; Balokovic, M.; Stern, D.; Arevalo, P.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Zhang, W. W.

    2015-01-01

    The covering factor of Compton-thick (CT) obscuring material associated with the torus in active galactic nuclei (AGNs) is at present best understood through the fraction of sources exhibiting CT absorption along the line of sight (N(sub H) greater than 1.5 x 10(exp 24) cm(exp -2)) in the X-ray band, which reveals the average covering factor. Determining this CT fraction is difficult, however, due to the extreme obscuration. With its spectral coverage at hard X-rays (greater than 10 keV), Nuclear Spectroscopic Telescope Array (NuSTAR) is sensitive to the AGNs covering factor since Compton scattering of X-rays off optically thick material dominates at these energies. We present a spectral analysis of 10 AGNs observed with NuSTAR where the obscuring medium is optically thick to Compton scattering, so-called CT AGNs. We use the torus models of Brightman and Nandra that predict the X-ray spectrum from reprocessing in a torus and include the torus opening angle as a free parameter and aim to determine the covering factor of the CT gas in these sources individually. Across the sample we find mild to heavy CT columns, with N(sub H) measured from 10(exp 24) to 10(exp 26) cm(exp -2), and a wide range of covering factors, where individual measurements range from 0.2 to 0.9. We find that the covering factor, f(sub c), is a strongly decreasing function of the intrinsic 2-10 keV luminosity, L(sub X), where f(sub c) = (-0.41 +/- 0.13)log(sub 10)(L(sub X)/erg s(exp -1))+18.31 +/- 5.33, across more than two orders of magnitude in L(sub X) (10(exp 41.5) - 10(exp 44) erg s(exp -1)). The covering factors measured here agree well with the obscured fraction as a function of LX as determined by studies of local AGNs with L(sub X) greater than 10(exp 42.5) erg s(exp -1).

  4. The NuSTAR View of Nearby Compton-thick Active Galactic Nuclei: The Cases of NGC 424, NGC 1320, and IC 2560

    Energy Technology Data Exchange (ETDEWEB)

    Baloković, M.; Comastri, A.; Harrison, F. A.; Alexander, D. M.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Moro, A. Del; Gandhi, P.; Hailey, C. J.; Koss, M.; Lansbury, G. B.; Luo, B.; Madejski, G. M.; Marinucci, A.; Matt, G.; Markwardt, C. B.; Puccetti, S.; Reynolds, C. S.; Risaliti, G.; Rivers, E.; Stern, D.; Walton, D. J.; Zhang, W. W.

    2014-09-30

    We present X-ray spectral analyses for three Seyfert 2 active galactic nuclei, NGC 424, NGC 1320, and IC 2560, observed by NuSTAR in the 3-79 keV band. The high quality hard X-ray spectra allow detailed modeling of the Compton reflection component for the first time in these sources. Using quasi-simultaneous NuSTAR and Swift/XRT data, as well as archival XMM-Newton data, we find that all three nuclei are obscured by Compton-thick material with column densities in excess of ~ 5 x 1024 cm-2, and that their X-ray spectra above 3 keV are dominated by reflection of the intrinsic continuum on Compton-thick material. Due to the very high obscuration, absorbed intrinsic continuum components are not formally required by the data in any of the sources. We constrain the intrinsic photon indices and the column density of the reflecting medium through the shape of the reflection spectra. Using archival multi-wavelength data we recover the intrinsic X-ray luminosities consistent with the broadband spectral energy distributions. Our results are consistent with the reflecting medium being an edge-on clumpy torus with a relatively large global covering factor and overall reflection efficiency of the order of 1%. Given the unambiguous confirmation of the Compton-thick nature of the sources, we investigate whether similar sources are likely to be missed by commonly used selection criteria for Compton-thick AGN, and explore the possibility of finding their high-redshift counterparts.

  5. CONSTRAINTS ON COMPTON-THICK WINDS FROM BLACK HOLE ACCRETION DISKS: CAN WE SEE THE INNER DISK?

    International Nuclear Information System (INIS)

    Reynolds, Christopher S.

    2012-01-01

    Strong evidence is emerging that winds can be driven from the central regions of accretion disks in both active galactic nuclei and Galactic black hole binaries. Direct evidence for highly ionized, Compton-thin inner-disk winds comes from observations of blueshifted (v ∼ 0.05-0.1c) iron-K X-ray absorption lines. However, it has been suggested that the inner regions of black hole accretion disks can also drive Compton-thick winds—such winds would enshroud the inner disk, preventing us from seeing direct signatures of the accretion disk (i.e., the photospheric thermal emission, or the Doppler/gravitationally broadened iron Kα line). Here, we show that, provided the source is sub-Eddington, the well-established wind-driving mechanisms fail to launch a Compton-thick wind from the inner disk. For the accelerated region of the wind to be Compton-thick, the momentum carried in the wind must exceed the available photon momentum by a factor of at least 2/λ, where λ is the Eddington ratio of the source, ruling out radiative acceleration unless the source is very close to the Eddington limit. Compton-thick winds also carry large mass fluxes, and a consideration of the connections between the wind and the disk shows this to be incompatible with magneto-centrifugal driving. Finally, thermal driving of the wind is ruled out on the basis of the large Compton radii that typify black hole systems. In the absence of some new acceleration mechanisms, we conclude that the inner regions of sub-Eddington accretion disks around black holes are indeed naked.

  6. A COMPTON-THICK ACTIVE GALACTIC NUCLEUS AT z ∼ 5 IN THE 4 Ms CHANDRA DEEP FIELD SOUTH

    International Nuclear Information System (INIS)

    Gilli, R.; Comastri, A.; Su, J.; Norman, C.; Vignali, C.; Tozzi, P.; Rosati, P.; Mainieri, V.; Stiavelli, M.; Brandt, W. N.; Xue, Y. Q.; Luo, B.; Castellano, M.; Fontana, A.; Fiore, F.; Ptak, A.

    2011-01-01

    We report the discovery of a Compton-thick active galactic nucleus (AGN) at z = 4.76 in the 4 Ms Chandra Deep Field South. This object was selected as a V-band dropout in HST/ACS images and previously recognized as an AGN from optical spectroscopy. The 4 Ms Chandra observations show a significant (∼4.2σ) X-ray detection at the V-band dropout position. The X-ray source displays a hardness ratio of HR = 0.23 ± 0.24, which, for a source at z ∼ 5, is highly suggestive of Compton-thick absorption. The source X-ray spectrum is seen above the background level in the energy range of ∼0.9-4 keV, i.e., in the rest-frame energy range of ∼5-23 keV. When fixing the photon index to Γ = 1.8, the measured column density is N H = 1.4 +0.9 -0.5 x 10 24 cm -2 , which is Compton thick. To our knowledge, this is the most distant heavily obscured AGN, confirmed by X-ray spectral analysis, discovered so far. The intrinsic (de-absorbed), rest-frame luminosity in the 2-10 keV band is ∼2.5 x 10 44 erg s -1 , which places this object among type-2 quasars. The spectral energy distribution shows that massive star formation is associated with obscured black hole (BH) accretion. This system may have then been caught during a major coeval episode of BH and stellar mass assembly at early times. The measure of the number density of heavily obscured AGN at high redshifts will be crucial to reconstructing the BH/galaxy evolution history from the beginning.

  7. The Compton-thick Growth of Supermassive Black Holes constrained

    Science.gov (United States)

    Buchner, J.; Georgakakis, A.; Nandra, K.

    2017-10-01

    A heavily obscured growth phase of supermassive black holes (SMBH) is thought to be important in the co-evolution with galaxies. X-rays provide a clean and efficient selection of unobscured and obscured AGN. Recent work with deeper observations and improved analysis methodology allowed us to extend constraints to Compton-thick number densities. We present the first luminosity function of Compton-thick AGN at z=0.5-4 and constrain the overall mass density locked into black holes over cosmic time, a fundamental constraint for cosmological simulations. Recent studies including ours find that the obscuration is redshift and luminosity-dependent in a complex way, which rules out entire sets of obscurer models. A new paradigm, the radiation-lifted torus model, is proposed, in which the obscurer is Eddington-rate dependent and accretion creates and displaces torus clouds. We place observational limits on the behaviour of this mechanism.

  8. Suzaku  Observations of Heavily Obscured (Compton-thick) Active Galactic Nuclei Selected by the Swift/BAT Hard X-Ray Survey

    Science.gov (United States)

    Tanimoto, Atsushi; Ueda, Yoshihiro; Kawamuro, Taiki; Ricci, Claudio; Awaki, Hisamitsu; Terashima, Yuichi

    2018-02-01

    We present a uniform broadband X-ray (0.5–100.0 keV) spectral analysis of 12 Swift/Burst Alert Telescope selected Compton-thick ({log}{N}{{H}}/{{cm}}-2≥slant 24) active galactic nuclei (CTAGNs) observed with Suzaku. The Suzaku data of three objects are published here for the first time. We fit the Suzaku and Swift spectra with models utilizing an analytic reflection code and those utilizing the Monte-Carlo-based model from an AGN torus by Ikeda et al. The main results are as follows: (1) The estimated intrinsic luminosity of a CTAGN strongly depends on the model; applying Compton scattering to the transmitted component in an analytic model may largely overestimate the intrinsic luminosity at large column densities. (2) Unabsorbed reflection components are commonly observed, suggesting that the tori are clumpy. (3) Most of CTAGNs show small scattering fractions (<0.5%), implying a buried AGN nature. (4) Comparison with the results obtained for Compton-thin AGNs suggests that the properties of these CTAGNs can be understood as a smooth extension from Compton-thin AGNs with heavier obscuration; we find no evidence that the bulk of the population of hard-X-ray-selected CTAGNs are different from less obscured objects.

  9. Towards A Complete Census of Compton-thick AGN and N_H Distribution in the Local Universe

    Science.gov (United States)

    Annuar, A.; Gandhi, P.; Alexander, D.; Asmus, D.; Goulding, A.; Harrison, C.; Lansbury, G.

    2014-07-01

    Many studies have shown that Compton-thick AGNs (CTAGNs) provide important contribution to the cosmic X-ray background spectrum (˜25% at 20keV). They are expected to dominate the Seyfert 2 population in the local universe, yet only ˜20 bona fide CTAGNs are known. We present an updated census of CTAGN population in the local universe using a volume-limited AGN sample complete to D=15Mpc. Intrinsic relations between 2-10keV X-ray luminosity and mid-IR emission at 12μm, [OIV]λ25.68μm and [NeV]λ14.32μm are investigated, and it is found that the emission at 12μm has the tightest correlation with the X-ray luminosity.Candidates for CTAGN are then selected using this relation and by comparing their 12μm luminosity with the observed X-ray luminosity.We also investigate the Compton-thick nature of these sources using the optical [OIII]λ5007{A}:X-ray diagnostic for comparison, and find that 35-50% of the sample are Compton-thick,of which 10-20% would be missed with the optical approach.Finally, we estimate the intrinsic N_{H} distribution of AGN population in the local universe from this analysis, and show that up to 70% of the sources are heavily obscured (N_{H}>10^{23} cm^{-2}), with ≥50% lying in the Compton-thick regime (N_{H}>10^{24} cm^{-2}).This work provides a well-defined local benchmark for AGN obscuration studies.

  10. The weak neutral Fe fluorescence line and long-term X-ray evolution of the Compton-thick AGN in NGC 7674

    DEFF Research Database (Denmark)

    Gandhi, P.; Annuar, A.; Lansbury, G. B.

    2017-01-01

    We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a rec...

  11. Effect of detector collimator and sample thickness on 0.662 MeV multiply Compton-scattered gamma rays

    International Nuclear Information System (INIS)

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

    2006-01-01

    The simultaneous effect of detector collimator and sample thickness on 0.662 MeV multiply Compton-scattered gamma photons was studied experimentally. An intense collimated beam, obtained from 6-Ci 137 Cs source, is allowed to impinge on cylindrical aluminium samples of varying diameter and the scattered photons are detected by a 51 mmx51 mm NaI(Tl) scintillation detector placed at 90 o to the incident beam. The full energy peak corresponding to singly scattered events is reconstructed analytically. The thickness at which the multiply scattered events saturate is determined for different detector collimators. The parameters like signal-to-noise ratio and multiply scatter fraction (MSF) have also been deduced and support the work carried out by Shengli et al. [2000. EGS4 simulation of Compton scattering for nondestructive testing. KEK proceedings 200-20, Tsukuba, Japan, pp. 216-223] and Barnea et al. [1995. A study of multiple scattering background in Compton scatter imaging. NDT and E International 28, 155-162] based upon Monte Carlo calculations

  12. A SUPER-EDDINGTON, COMPTON-THICK WIND IN GRO J1655–40?

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, J.; Homan, J. [MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA 02139 (United States); Rahoui, F. [European Southern Observatory, Karl Schwarzschild-Strasse 2, D-85748 Garching bei Munchen (Germany); Buxton, M., E-mail: jneilsen@space.mit.edu [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)

    2016-05-01

    During its 2005 outburst, GRO J1655–40 was observed at high spectral resolution with the Chandra High-Energy Transmission Grating Spectrometer, revealing a spectrum rich with blueshifted absorption lines indicative of an accretion disk wind—apparently too hot, too dense, and too close to the black hole to be driven by radiation pressure or thermal pressure (Miller et al.). However, this exotic wind represents just one piece of the puzzle in this outburst, as its presence coincides with an extremely soft and curved X-ray continuum spectrum, remarkable X-ray variability (Uttley and Klein-Wolt), and a bright, unexpected optical/infrared blackbody component that varies on the orbital period. Focusing on the X-ray continuum and the optical/infrared/UV spectral energy distribution, we argue that the unusual features of this “hypersoft state” are natural consequences of a super-Eddington Compton-thick wind from the disk: the optical/infrared blackbody represents the cool photosphere of a dense, extended outflow, while the X-ray emission is explained as Compton scattering by the relatively cool, optically thick wind. This wind obscures the intrinsic luminosity of the inner disk, which we suggest may have been at or above the Eddington limit.

  13. The 2-79 keV X-ray spectrum of the Circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully Compton-thick active galactic nucleus

    International Nuclear Information System (INIS)

    Arévalo, P.; Bauer, F. E.; Puccetti, S.; Walton, D. J.; Fuerst, F.; Grefenstette, B. W.; Harrison, F. A.; Madsen, K. K.; Koss, M.; Boggs, S. E.; Craig, W. W.; Brandt, W. N.; Luo, B.; Brightman, M.; Christensen, F. E.; Comastri, A.; Gandhi, P.; Hailey, C. J.; Madejski, G.; Marinucci, A.

    2014-01-01

    The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical parameters for the obscuring material. Chandra's high angular resolution allows a separation of nuclear and off-nuclear galactic emission. In the off-nuclear diffuse emission, we find signatures of strong cold reflection, including high equivalent-width neutral Fe lines. This Compton-scattered off-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton scattering by an optically thick torus, where the intrinsic spectrum is a power law of photon index Γ = 2.2-2.4, the torus has an equatorial column density of N H = (6-10) × 10 24 cm –2 , and the intrinsic AGN 2-10 keV luminosity is (2.3-5.1) × 10 42 erg s –1 . These values place Circinus along the same relations as unobscured AGNs in accretion rate versus Γ and L X versus L IR phase space. NuSTAR's high sensitivity and low background allow us to study the short timescale variability of Circinus at X-ray energies above 10 keV for the first time. The lack of detected variability favors a Compton-thick absorber, in line with the spectral fitting results.

  14. The weak Fe fluorescence line and long-term X-ray evolution of the Compton-thick active galactic nucleus in NGC 7674

    Science.gov (United States)

    Gandhi, P.; Annuar, A.; Lansbury, G. B.; Stern, D.; Alexander, D. M.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Comastri, A.; Craig, W. W.; Del Moro, A.; Elvis, M.; Guainazzi, M.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Lamperti, I.; Malaguti, G.; Masini, A.; Matt, G.; Puccetti, S.; Ricci, C.; Rivers, E.; Walton, D. J.; Zhang, W. W.

    2017-06-01

    We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC 7674. The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe Kα emission line (equivalent width [EW] of ≈ 0.4 keV) and a strong Fe xxvi ionized line (EW ≈ 0.2 keV). We construct an updated long-term X-ray light curve of NGC 7674 and find that the observed 2-10 keV flux has remained constant for the past ≈ 20 yr, following a high-flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be ˜ 3.2 pc under the switched-off AGN scenario, ≈ 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (NH) of 3 × 1024 cm-2 at present, and yields an intrinsic 2-10 keV luminosity of (3-5) × 1043 erg s-1. Realistic uncertainties span the range of ≈ (1-13) × 1043 erg s-1. The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionized Fe emission. It exemplifies the difficulty of identification and proper characterization of distant CTAGN based on the strength of the neutral Fe Kα line.

  15. The Weak Fe Fluorescence Line and Long-Term X-Ray Evolution of the Compton-Thick Active Galactic Nucleus in NGC7674

    Science.gov (United States)

    Ghandi, P.; Annuar, A.; Lansbury, G. B.; Stern, D.; Alexander, D. M.; Bauer, F. E.; Bianchi, S.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; hide

    2017-01-01

    We present NuSTAR X-ray observations of the active galactic nucleus (AGN) in NGC7674.The source shows a flat X-ray spectrum, suggesting that it is obscured by Compton-thick gas columns. Based upon long-term flux dimming, previous work suggested the alternate possibility that the source is a recently switched-off AGN with the observed X-rays being the lagged echo from the torus. Our high-quality data show the source to be reflection-dominated in hard X-rays, but with a relatively weak neutral Fe K(alpha) emission line (equivalent width [EW] of approximately 0.4 keV) and a strong Fe XXVI ionized line (EW approximately 0.2 keV).We construct an updated long-term X-ray light curve of NGC7674 and find that the observed 2-10 keV flux has remained constant for the past approximately 20 yr, following a high-flux state probed by Ginga. Light travel time arguments constrain the minimum radius of the reflector to be approximately 3.2 pc under the switched-off AGN scenario, approximately 30 times larger than the expected dust sublimation radius, rendering this possibility unlikely. A patchy Compton-thick AGN (CTAGN) solution is plausible, requiring a minimum line-of-sight column density (N(sub H)) of 3 x 10(exp 24) cm(exp -2) at present, and yields an intrinsic 2-10 keV luminosity of (3-5) x 10(exp 43) erg s(exp -1). Realistic uncertainties span the range of approximately (1-13) x 10(exp 43) erg s1. The source has one of the weakest fluorescence lines amongst bona fide CTAGN, and is potentially a local analogue of bolometrically luminous systems showing complex neutral and ionized Fe emission. It exemplifies the difficulty of identification and proper characterization of distant CTAGN based on the strength of the neutral Fe K line

  16. Thick silicon microstrip detectors simulation for PACT: Pair and Compton Telescope

    Science.gov (United States)

    Khalil, M.; Laurent, P.; Lebrun, F.; Tatischeff, V.; Dolgorouky, Y.; Bertoli, W.; Breelle, E.

    2016-11-01

    PACT is a space borne Pair and Compton Telescope that aims to make a sensitive survey of the gamma-ray sky between 100 keV and 100 MeV. It is based upon two main components: a silicon-based gamma-ray tracker and a crystal-based calorimeter. In this paper we will explain the imaging technique of PACT as a Multi-layered Compton telescope (0.1-10 MeV) and its major improvements over its predecessor COMPTEL. Then we will present a simulation study to optimize the silicon tracker of PACT. This tracker is formed of thousands of identical silicon double sided strip detectors (DSSDs). We have developed a simulation model (using SILVACO) to simulate the DSSD performance while varying its thickness, impurity concentration of the bulk material, electrode pitch, and electrode width. We will present a comprehensive overview of the impact of each varied parameter on the DSSD performance, in view of the application to PACT. The considered DSSD parameters are its depletion voltage, capacitance, and leakage current. After the selection of the PACT DSSD, we will present a simulation of the performance of the PACT telescope in the 0.1-10 MeV range.

  17. Thick silicon microstrip detectors simulation for PACT: Pair and Compton Telescope

    International Nuclear Information System (INIS)

    Khalil, M.; Laurent, P.; Lebrun, F.; Tatischeff, V.; Dolgorouky, Y.; Bertoli, W.; Breelle, E.

    2016-01-01

    PACT is a space borne Pair and Compton Telescope that aims to make a sensitive survey of the gamma-ray sky between 100 keV and 100 MeV. It is based upon two main components: a silicon-based gamma-ray tracker and a crystal-based calorimeter. In this paper we will explain the imaging technique of PACT as a Multi-layered Compton telescope (0.1–10 MeV) and its major improvements over its predecessor COMPTEL. Then we will present a simulation study to optimize the silicon tracker of PACT. This tracker is formed of thousands of identical silicon double sided strip detectors (DSSDs). We have developed a simulation model (using SILVACO) to simulate the DSSD performance while varying its thickness, impurity concentration of the bulk material, electrode pitch, and electrode width. We will present a comprehensive overview of the impact of each varied parameter on the DSSD performance, in view of the application to PACT. The considered DSSD parameters are its depletion voltage, capacitance, and leakage current. After the selection of the PACT DSSD, we will present a simulation of the performance of the PACT telescope in the 0.1–10 MeV range.

  18. Thick silicon microstrip detectors simulation for PACT: Pair and Compton Telescope

    Energy Technology Data Exchange (ETDEWEB)

    Khalil, M., E-mail: khalilmohammad@hotmail.com [APC Laboratory, 10rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); Laurent, P.; Lebrun, F. [APC Laboratory, 10rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France); CEA, Centre de Saclay, 91191 Gif-Sur-Yvette Cedex (France); Tatischeff, V. [CSNSM, IN2P3/CNRSand Paris-Sud University, 91405 Orsay Campus (France); Dolgorouky, Y.; Bertoli, W.; Breelle, E. [APC Laboratory, 10rue Alice Domon et Léonie Duquet, 75205 Paris Cedex 13 (France)

    2016-11-01

    PACT is a space borne Pair and Compton Telescope that aims to make a sensitive survey of the gamma-ray sky between 100 keV and 100 MeV. It is based upon two main components: a silicon-based gamma-ray tracker and a crystal-based calorimeter. In this paper we will explain the imaging technique of PACT as a Multi-layered Compton telescope (0.1–10 MeV) and its major improvements over its predecessor COMPTEL. Then we will present a simulation study to optimize the silicon tracker of PACT. This tracker is formed of thousands of identical silicon double sided strip detectors (DSSDs). We have developed a simulation model (using SILVACO) to simulate the DSSD performance while varying its thickness, impurity concentration of the bulk material, electrode pitch, and electrode width. We will present a comprehensive overview of the impact of each varied parameter on the DSSD performance, in view of the application to PACT. The considered DSSD parameters are its depletion voltage, capacitance, and leakage current. After the selection of the PACT DSSD, we will present a simulation of the performance of the PACT telescope in the 0.1–10 MeV range.

  19. Applicability of compton imaging in nuclear decommissioning activities

    International Nuclear Information System (INIS)

    Ljubenov, V.Lj.; Marinkovic, P.M.

    2002-01-01

    During the decommissioning of nuclear facilities significant part of the activities is related to the radiological characterization, waste classification and management. For these purposes a relatively new imaging technique, based on information from the gamma radiation that undergoes Compton scattering, is applicable. Compton imaging systems have a number of advantages for nuclear waste characterization, such as identifying hot spots in mixed waste in order to reduce the volume of high-level waste requiring extensive treatment or long-term storage, imaging large contaminated areas and objects etc. Compton imaging also has potential applications for monitoring of production, transport and storage of nuclear materials and components. This paper discusses some system design requirements and performance specifications for these applications. The advantages of Compton imaging are compared to competing imaging techniques. (author)

  20. The Contribution of Compton-Thick AGN/ULIRGs to the X-Ray Background

    Science.gov (United States)

    Nardini, Emanuele

    Accretion onto the supermassive black holes located at the centre of Active Galactic Nuclei(AGN) is one of the most efficient power sources in the Universe, and provides a significant contribution to the energy radiated over cosmic times. The spectral shape of the X-ray background and its progressive resolution strongly suggests that most AGN are heavily obscured by large amounts of dust and gas. Their primary radiation field is reprocessed and re-emitted at longer wavelengths, driving a huge IR luminosity. Ultraluminous Infrared Galaxies (ULIRGs) are the local counterparts of the high-redshift (z sport the typical features of buried AGN in the mid-IR. IRAS 12127 1412 was observed for the first time in the X-rays by our group. Its Chandra spectrum clearly shows the signatures of AGN reflection at 2 10 keV. Similar properties were previously found in IRAS 00182 7112. Our Suzaku observations will allow to pinpont the AGN emission above 10 keV, and will provide fundamental information on the physical and geometrical structure of Compton-thick AGN embedded in a nuclear starburst. These sources are believed to experience the very initial phase of the AGN feedback on the surrounding environment, eventually leading to the formation of powerful optically- bright quasars. Besides this, we stress another remarkable opportunity related to the study of these two ULIRGs. Due to their really unique mid-IR and hard X-ray spectral properties, IRAS 00182 7112 and IRAS 12127 1412 can be considered as representative templates for a significant fraction of the obscured AGN population. Their broadband spectral energy distribution can then be used to calibrate new photometric diagnostics based on mid-IR colors and bolometric corrections, capable of selecting their faint counterparts within the IR deep fields. The wealth of data in the WISE and Spitzer archives will allow a complete census of this AGN subclass. The reflection efficiency inferred from our new Suzaku observations will make

  1. Description of the double Compton spectrometer at Mayence MPI

    International Nuclear Information System (INIS)

    Borchert, H.; Ziegler, B.; Gimm, H.; Zieger, A.; Hughes, R.J.; Ahrens, J.

    1977-01-01

    The double Compton spectrometer of the Laboratories of the Mayence Linear Accelerator consists in two identical magnetic spectrometers, in which the electron scattered forwards by photons through a Compton process, are detected. The spectrometers have been built to detect 10-350 MeV photons and, as they involve thin Compton targets, their effect on the photon flux is negligible. They are put in cascade inside a well collimated bremsstrahlung beam. A thick absorbing target (max. thickness 2m) can be inserted inside the beam. The facility is outlined, some special properties of the accelerator and the bremsstrahlung beam are given. The properties of a Compton spectrometer involving eleven detectors are given by eleven response functions giving the relations between the photon flux impinging the Compton target and the counting rates of the detectors for a given adjustment of the magnets. A Monte-Carlo method is used for the calculation together with analytical methods neglecting the multiple scattering effects [fr

  2. Arthur H. Compton and Compton Scattering

    Science.gov (United States)

    dropdown arrow Site Map A-Z Index Menu Synopsis Arthur H. Compton and Compton Scattering Resources with Additional Information * Compton Honored * Compton Scattering Arthur H. Compton Courtesy of Lawrence Berkeley , 1923 Establishing Site X: Letter, Arthur H. Compton to Enrico Fermi, September 14, 1942, DOE Technical

  3. Compton effect thermally activated depolarization dosimeter

    Science.gov (United States)

    Moran, Paul R.

    1978-01-01

    A dosimetry technique for high-energy gamma radiation or X-radiation employs the Compton effect in conjunction with radiation-induced thermally activated depolarization phenomena. A dielectric material is disposed between two electrodes which are electrically short circuited to produce a dosimeter which is then exposed to the gamma or X radiation. The gamma or X-radiation impinging on the dosimeter interacts with the dielectric material directly or with the metal composing the electrode to produce Compton electrons which are emitted preferentially in the direction in which the radiation was traveling. A portion of these electrons becomes trapped in the dielectric material, consequently inducing a stable electrical polarization in the dielectric material. Subsequent heating of the exposed dosimeter to the point of onset of ionic conductivity with the electrodes still shorted through an ammeter causes the dielectric material to depolarize, and the depolarization signal so emitted can be measured and is proportional to the dose of radiation received by the dosimeter.

  4. Toward the standard population synthesis model of the X-ray background: Evolution of X-ray luminosity and absorption functions of active galactic nuclei including Compton-thick populations

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, Yoshihiro [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Akiyama, Masayuki [Astronomical Institute, Tohoku University, 6-3 Aramaki, Aoba-ku, Sendai 980-8578 (Japan); Hasinger, Günther [Institute for Astronomy, 2680 Woodlawn Drive Honolulu, HI 96822-1839 (United States); Miyaji, Takamitsu [Instituto de Astronomía, Universidad Nacional Autónoma de México, Ensenada, Baja California (Mexico); Watson, Michael G. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

    2014-05-10

    We present the most up to date X-ray luminosity function (XLF) and absorption function of active galactic nuclei (AGNs) over the redshift range from 0 to 5, utilizing the largest, highly complete sample ever available obtained from surveys performed with Swift/BAT, MAXI, ASCA, XMM-Newton, Chandra, and ROSAT. The combined sample, including that of the Subaru/XMM-Newton Deep Survey, consists of 4039 detections in the soft (0.5-2 keV) and/or hard (>2 keV) band. We utilize a maximum likelihood method to reproduce the count rate versus redshift distribution for each survey, by taking into account the evolution of the absorbed fraction, the contribution from Compton-thick (CTK) AGNs, and broadband spectra of AGNs, including reflection components from tori based on the luminosity- and redshift-dependent unified scheme. We find that the shape of the XLF at z ∼ 1-3 is significantly different from that in the local universe, for which the luminosity-dependent density evolution model gives much better description than the luminosity and density evolution model. These results establish the standard population synthesis model of the X-ray background (XRB), which well reproduces the source counts, the observed fractions of CTK AGNs, and the spectrum of the hard XRB. The number ratio of CTK AGNs to the absorbed Compton-thin (CTN) AGNs is constrained to be ≈0.5-1.6 to produce the 20-50 keV XRB intensity within present uncertainties, by assuming that they follow the same evolution as CTN AGNs. The growth history of supermassive black holes is discussed based on the new AGN bolometric luminosity function.

  5. Compton suppression gamma ray spectrometry

    International Nuclear Information System (INIS)

    Landsberger, S.; Iskander, F.Y.; Niset, M.; Heydorn, K.

    2002-01-01

    In the past decade there have been many studies to use Compton suppression methods in routine neutron activation analysis as well as in the traditional role of low level gamma ray counting of environmental samples. On a separate path there have been many new PC based software packages that have been developed to enhance photopeak fitting. Although the newer PC based algorithms have had significant improvements, they still suffer from being effectively used in weak gamma ray lines in natural samples or in neutron activated samples that have very high Compton backgrounds. We have completed a series of experiments to show the usefulness of Compton suppression. As well we have shown the pitfalls when using Compton suppression methods for high counting deadtimes as in the case of neutron activated samples. We have also investigated if counting statistics are the same both suppressed and normal modes. Results are presented in four separate experiments. (author)

  6. NuSTAR OBSERVATIONS OF THE COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND ULTRALUMINOUS X-RAY SOURCE CANDIDATE IN NGC 5643

    International Nuclear Information System (INIS)

    Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Moro, A. Del; Arévalo, P.; Ballantyne, D. R.; Baloković, M.; Brightman, M.; Harrison, F. A.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Brandt, W. N.; Christensen, F. E.; Hailey, C. J.; Hickox, R. C.; Matt, G.; Puccetti, S.; Ricci, C.

    2015-01-01

    We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (∼0.5–100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X–1, have left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X–1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of N H ≳ 5 × 10 24 cm −2 . The range of 2–10 keV absorption-corrected luminosity inferred from the best-fitting models is L 2–10,int = (0.8–1.7) × 10 42 erg s −1 , consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X–1 and show that it exhibits evidence of a spectral cutoff at energy E ∼ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3–8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X–1

  7. NuSTAR Observations of the Compton-thick Active Galactic Nucleus and Ultraluminous X-Ray Source Candidate in NGC 5643

    Science.gov (United States)

    Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Arévalo, P.; Ballantyne, D. R.; Baloković, M.; Bauer, F. E.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Del Moro, A.; Hailey, C. J.; Harrison, F. A.; Hickox, R. C.; Matt, G.; Puccetti, S.; Ricci, C.; Rigby, J. R.; Stern, D.; Walton, D. J.; Zappacosta, L.; Zhang, W.

    2015-12-01

    We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (˜0.5-100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X-1, have left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X-1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of NH ≳ 5 × 1024 cm-2. The range of 2-10 keV absorption-corrected luminosity inferred from the best-fitting models is L2-10,int = (0.8-1.7) × 1042 erg s-1, consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X-1 and show that it exhibits evidence of a spectral cutoff at energy E ˜ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3-8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X-1.

  8. Compton radiography, 4. Magnification compton radiography

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, S; Sera, K; Shishido, F; Fukuda, H [Tohoku Univ., Sendai (Japan). Research Inst. for Tuberculosis and Cancer; Mishina, H

    1978-03-01

    Compton radiography permits an acquisition of direct magnification Compton radiograms by use of a pinhole collimator, rendering it feasible to overcome the resolution of the scinticamera being employed. An improvement of resolution was attained from 7 mm to 1 mm separation. Usefulness of its clinical application can be seen in orientation of puncture and biopsy in deep structures and detection of various foreign bodies penetrated by blasts and so on under the ''magnification Compton fluoroscopy'' which can be developed on this principle in the near future.

  9. Optimisation of a dual head semiconductor Compton camera using Geant4

    Energy Technology Data Exchange (ETDEWEB)

    Harkness, L.J. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L697ZE (United Kingdom)], E-mail: ljh@ns.ph.liv.ac.uk; Boston, A.J.; Boston, H.C.; Cooper, R.J.; Cresswell, J.R.; Grint, A.N.; Nolan, P.J.; Oxley, D.C.; Scraggs, D.P. [Department of Physics, University of Liverpool, Oliver Lodge Laboratory, Liverpool L697ZE (United Kingdom); Beveridge, T.; Gillam, J. [School of Physics and Materials Engineering, Monash University, Melbourne (Australia); Lazarus, I. [STFC Daresbury Laboratory, Warrington, Cheshire (United Kingdom)

    2009-06-01

    Conventional medical gamma-ray camera systems utilise mechanical collimation to provide information on the position of an incident gamma-ray photon. Systems that use electronic collimation utilising Compton image reconstruction techniques have the potential to offer huge improvements in sensitivity. Position sensitive high purity germanium (HPGe) detector systems are being evaluated as part of a single photon emission computed tomography (SPECT) Compton camera system. Data have been acquired from the orthogonally segmented planar SmartPET detectors, operated in Compton camera mode. The minimum gamma-ray energy which can be imaged by the current system in Compton camera configuration is 244 keV due to the 20 mm thickness of the first scatter detector which causes large gamma-ray absorption. A simulation package for the optimisation of a new semiconductor Compton camera has been developed using the Geant4 toolkit. This paper will show results of preliminary analysis of the validated Geant4 simulation for gamma-ray energies of SPECT, 141 keV.

  10. IC 3639 - A New Bona Fide Compton-Thick AGN Unveiled By NuSTAR

    Science.gov (United States)

    Boorman, Peter G.; Gandhi, P.; Alexander, D. M.; Annuar, A.; Ballantyne, D. R.; Bauer, F.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; hide

    2016-01-01

    We analyze high-quality NuSTAR observations of the local (z = 0.011) Seyfert 2 active galactic nucleus (AGN) IC 3639, in conjunction with archival Suzaku and Chandra data. This provides the first broadband X-ray spectral analysis of the source, spanning nearly two decades in energy (0.5-30 keV). Previous X-ray observations of the source below 10 keV indicated strong reflection/obscuration on the basis of a pronounced iron fluorescence line at 6.4 keV. The hard X-ray energy coverage of NuSTAR, together with self-consistent toroidal reprocessing models, enables direct broadband constraints on the obscuring column density of the source. We find the source to be heavily Compton-thick (CTK) with an obscuring column in excess of 3.6 x 10(exp 24) cm(exp -2), unconstrained at the upper end. We further find an intrinsic 2-10 keV luminosity of log(sub 10) (L(sub 2-10 keV) [erg s(exp -1)])= 43.4(+0.6/-1.1) to 90% confidence, almost 400 times the observed flux, and consistent with various multiwavelength diagnostics. Such a high ratio of intrinsic to observed flux, in addition to an Fe-K(alpha) fluorescence line equivalent width exceeding 2 keV, is extreme among known bona fide CTK AGNs, which we suggest are both due to the high level of obscuration present around IC 3639. Our study demonstrates that broadband spectroscopic modeling with NuSTAR enables large corrections for obscuration to be carried out robustly and emphasizes the need for improved modeling of AGN tori showing intense iron fluorescence.

  11. IC 3639—a New Bona Fide Compton-Thick AGN Unveiled by NuSTAR

    Science.gov (United States)

    Boorman, Peter G.; Gandhi, P.; Alexander, D. M.; Annuar, A.; Ballantyne, D. R.; Bauer, F.; Boggs, S. E.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Hönig, S. F.; Koss, M.; LaMassa, S. M.; Masini, A.; Ricci, C.; Risaliti, G.; Stern, D.; Zhang, W. W.

    2016-12-01

    We analyze high-quality NuSTAR observations of the local (z = 0.011) Seyfert 2 active galactic nucleus (AGN) IC 3639, in conjunction with archival Suzaku and Chandra data. This provides the first broadband X-ray spectral analysis of the source, spanning nearly two decades in energy (0.5-30 keV). Previous X-ray observations of the source below 10 keV indicated strong reflection/obscuration on the basis of a pronounced iron fluorescence line at 6.4 keV. The hard X-ray energy coverage of NuSTAR, together with self-consistent toroidal reprocessing models, enables direct broadband constraints on the obscuring column density of the source. We find the source to be heavily Compton-thick (CTK) with an obscuring column in excess of 3.6× {10}24 cm-2, unconstrained at the upper end. We further find an intrinsic 2-10 keV luminosity of {{log}}10({L}2{--10{keV}} [{erg} {{{s}}}-1])={43.4}-1.1+0.6 to 90% confidence, almost 400 times the observed flux, and consistent with various multiwavelength diagnostics. Such a high ratio of intrinsic to observed flux, in addition to an Fe-Kα fluorescence line equivalent width exceeding 2 keV, is extreme among known bona fide CTK AGNs, which we suggest are both due to the high level of obscuration present around IC 3639. Our study demonstrates that broadband spectroscopic modeling with NuSTAR enables large corrections for obscuration to be carried out robustly and emphasizes the need for improved modeling of AGN tori showing intense iron fluorescence.

  12. NuSTAR OBSERVATIONS OF THE COMPTON-THICK ACTIVE GALACTIC NUCLEUS AND ULTRALUMINOUS X-RAY SOURCE CANDIDATE IN NGC 5643

    Energy Technology Data Exchange (ETDEWEB)

    Annuar, A.; Gandhi, P.; Alexander, D. M.; Lansbury, G. B.; Moro, A. Del [Centre for Extragalactic Astronomy, Department of Physics, University of Durham, South Road, Durham, DH1 3LE (United Kingdom); Arévalo, P. [Instituto de Física y Astronomía, Facultad de Ciencias, Universidad de Valparaíso, Gran Bretana N 1111, Playa Ancha, Valparaíso (Chile); Ballantyne, D. R. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Baloković, M.; Brightman, M.; Harrison, F. A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Bauer, F. E. [EMBIGGEN Anillo, Concepción (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Brandt, W. N. [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Christensen, F. E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hickox, R. C. [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universitá degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Puccetti, S. [ASI Science Data Center, via Galileo Galilei, I-00044 Frascati (Italy); Ricci, C. [Department of Astronomy, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); and others

    2015-12-10

    We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband spectral analysis of the AGN over two decades in energy (∼0.5–100 keV). Previous X-ray observations suggested that the AGN is obscured by a Compton-thick (CT) column of obscuring gas along our line of sight. However, the lack of high-quality ≳10 keV observations, together with the presence of a nearby X-ray luminous source, NGC 5643 X–1, have left significant uncertainties in the characterization of the nuclear spectrum. NuSTAR now enables the AGN and NGC 5643 X–1 to be separately resolved above 10 keV for the first time and allows a direct measurement of the absorbing column density toward the nucleus. The new data show that the nucleus is indeed obscured by a CT column of N{sub H} ≳ 5 × 10{sup 24} cm{sup −2}. The range of 2–10 keV absorption-corrected luminosity inferred from the best-fitting models is L{sub 2–10,int} = (0.8–1.7) × 10{sup 42} erg s{sup −1}, consistent with that predicted from multiwavelength intrinsic luminosity indicators. In addition, we also study the NuSTAR data for NGC 5643 X–1 and show that it exhibits evidence of a spectral cutoff at energy E ∼ 10 keV, similar to that seen in other ULXs observed by NuSTAR. Along with the evidence for significant X-ray luminosity variations in the 3–8 keV band from 2003 to 2014, our results further strengthen the ULX classification of NGC 5643 X–1.

  13. A Compton-thick Wind in the High Luminosity Quasar, PDS 456

    Science.gov (United States)

    Reeves, J. N.; O'Brien, P. T.; Behar, E.; Miller, L.; Turner, T. J.; Braito, V.; Fabian, A. C.; Kaspi, S.; Mushotzky, R.; Ward, M.

    2009-01-01

    PDS 456 is a nearby (z=0.184), luminous (L(sub bol) approximately equal to 10(exp 47) ergs(exp -1) type I quasar. A deep 190 ks Suzaku observation in February 2007 revealed the complex, broad band X-ray spectrum of PDS 456. The Suzaku spectrum exhibits highly statistically significant absorption features near 9 keV in the quasar rest-frame. We show that the most plausible origin of the absorption is from blue-shifted resonance (1s-2p) transitions of hydrogen-like iron (at 6.97 keV in the rest frame). This indicates that a highly ionized outflow may be present moving at near relativistic velocities (0.26-0.31c). A possible hard X-ray excess is detected above 15 keV with HXD (at 99.8% confidence), which may arise from high column density gas (N(sub H) greater than 10(exp 24)cm(exp -2) partially covering the X-ray emission, or through strong Compton reflection. Here we propose that the iron K-shell absorption in PDS 456 is associated with a thick, possibly clumpy outflow, covering about 20% of 4(pi) steradian solid angle. The outflow is likely launched from the inner accretion disk, within 15-100 gravitational radii of the black hole. The kinetic power of the outflow may be similar to the bolometric luminosity of PDS 456. Such a powerful wind could have a significant effect on the co-evolution of the host galaxy and its supermassive black hole, through feedback.

  14. Compton radiography, 2

    International Nuclear Information System (INIS)

    Okuyama, Shinichi; Sera, Koichiro; Fukuda, Hiroshi; Shishido, Fumio; Mishina, Hitoshi.

    1977-01-01

    Compton radiography, a tomographic technic with Compton-scattered rays of a monochromatic gamma ray beam, was feasible of tomographing a chest phantom. The result suggested that the technic could be extended to imaging of the lung and the surrounding structures of the chest wall, mediastinum and liver in Compton tomographic mode. (auth.)

  15. Analysis of the factors that affect photon counts in Compton scattering

    International Nuclear Information System (INIS)

    Luo, Guang; Xiao, Guangyu

    2015-01-01

    Compton scattering has been applied in a variety of fields. The factors that affect Compton scattering have been studied extensively in the literature. However, the factors that affect the measured photon counts in Compton scattering are rarely considered. In this paper, we make a detailed discussion on those factors. First, Compton scattering experiments of some alloy series and powder mixture series are explored. Second, the electron density is researched in terms of atom and lattice constants. Third, the factor of attenuation coefficient is discussed. And then, the active degree of electrons is discussed based on the DFT theory. Lastly, the conclusions are made, that the factors affecting Compton scattering photon counts include mainly electron number density, attenuation coefficient and active degree of electrons. - Highlights: • Compton scattering experiments of some alloy series and powder mixture series are explored. • The influence of electron density is researched in terms of atom and lattice constants. • The influence of attenuation coefficient is discussed. • The active degree of electrons is discussed detailedly based on DFT theory

  16. Compton tomography system

    Science.gov (United States)

    Grubsky, Victor; Romanoov, Volodymyr; Shoemaker, Keith; Patton, Edward Matthew; Jannson, Tomasz

    2016-02-02

    A Compton tomography system comprises an x-ray source configured to produce a planar x-ray beam. The beam irradiates a slice of an object to be imaged, producing Compton-scattered x-rays. The Compton-scattered x-rays are imaged by an x-ray camera. Translation of the object with respect to the source and camera or vice versa allows three-dimensional object imaging.

  17. Developments in gamma-ray spectrometry: systems, software, and methods-II. 3. Low-Energy Gamma-Ray Spectrometry Using a Compton-Suppressed Telescope Detector

    International Nuclear Information System (INIS)

    Sigg, R.A.; DiPrete, D.P.

    2001-01-01

    The Savannah River Technology Center (SRTC) utilizes gamma-ray spectrometry in studying numerous areas of applied interest to the Savannah River Site (SRS). For example, analyses of long-lived gamma-ray-emitting fission products and actinides are required to meet waste characterization, process holdup, environmental restoration, and decontamination and decommissioning efforts. A significant portion of the overall effort centers on measurements of gamma rays having energies below several hundred kilo-electron-volts. To assist these efforts, the SRTC recently acquired a spectrometer system that provides lower natural and Compton scattered background levels while achieving relatively high counting efficiencies for low-energy gamma rays. The combination of high efficiency and low background provides factor-of- 2-to-4 improvements in minimum detectable activities and allows meeting programmatic objectives with shorter measurement times. Numerous Compton-suppression spectrometers have been reported since the concept was first advanced. The spectrometer consists of two high-purity germanium detectors in a telescope configuration surrounded by a background /Compton-suppression sodium iodide detector. The front germanium detector is a 20-mm-thick x 60-mm-diam broad energy spectrometer, and the rear detector is a 40% efficient 61- mm-diam x 60-cm-thick closed-end coaxial spectrometer. The cryostat housing the germanium detectors (a) includes a carbon composite window for transmitting low-energy gamma rays, (b) is in a J-type configuration to mask the germanium detectors from natural activities in the cryo-pumping media, and (c) is fabricated from materials selected for low background. The telescope detector is in the 8.6-cm-inside-diameter annulus of a 22.9- x 22.9-cm sodium iodide detector encased in a 10-cm-thick lead shield. The counting system is located in a basement counting room having ∼60-cm-thick concrete walls. Initial tests show that the low-energy segment of

  18. Compton radiography, 2. Clinical significance of Compton radiography of a chest phantom

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, S; Sera, K; Fukuda, H; Shishido, F [Tohoku Univ., Sendai (Japan). Research Inst. for Tuberculosis, Leprosy and Cancer; Mishina, H

    1977-09-01

    Compton radiography, a tomographic technic with Compton-scattered rays of a monochromatic gamma ray beam, was feasible of tomographing a chest phantom. The result suggested that the technic could be extended to imaging of the lung and the surrounding structures of the chest wall, mediastinum and liver in Compton tomographic mode.

  19. The NuSTAR Extragalactic Surveys: Source Catalog and the Compton-thick Fraction in the UDS Field

    Science.gov (United States)

    Masini, A.; Civano, F.; Comastri, A.; Fornasini, F.; Ballantyne, D. R.; Lansbury, G. B.; Treister, E.; Alexander, D. M.; Boorman, P. G.; Brandt, W. N.; Farrah, D.; Gandhi, P.; Harrison, F. A.; Hickox, R. C.; Kocevski, D. D.; Lanz, L.; Marchesi, S.; Puccetti, S.; Ricci, C.; Saez, C.; Stern, D.; Zappacosta, L.

    2018-03-01

    We present the results and the source catalog of the NuSTAR survey in the UKIDSS Ultra Deep Survey (UDS) field, bridging the gap in depth and area between NuSTAR’s ECDFS and COSMOS surveys. The survey covers a ∼0.6 deg2 area of the field for a total observing time of ∼1.75 Ms, to a half-area depth of ∼155 ks corrected for vignetting at 3–24 keV, and reaching sensitivity limits at half-area in the full (3–24 keV), soft (3–8 keV), and hard (8–24 keV) bands of 2.2 × 10‑14 erg cm‑2 s‑1, 1.0 × 10‑14 erg cm‑2 s‑1, and 2.7 × 10‑14 erg cm‑2 s‑1, respectively. A total of 67 sources are detected in at least one of the three bands, 56 of which have a robust optical redshift with a median of ∼ 1.1. Through a broadband (0.5–24 keV) spectral analysis of the whole sample combined with the NuSTAR hardness ratios, we compute the observed Compton-thick (CT; N H > 1024 cm‑2) fraction. Taking into account the uncertainties on each N H measurement, the final number of CT sources is 6.8 ± 1.2. This corresponds to an observed CT fraction of 11.5% ± 2.0%, providing a robust lower limit to the intrinsic fraction of CT active galactic nuclei and placing constraints on cosmic X-ray background synthesis models.

  20. Weak hard X-ray emission from two broad absorption line quasars observed with NuSTAR: Compton-thick absorption or intrinsic X-ray weakness?

    DEFF Research Database (Denmark)

    Luo, B.; Brandt, W. N.; Alexander, D. M.

    2013-01-01

    are not significantly absorbed (NH ≲ 1024 cm-2). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain...... likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place...

  1. Development of silicon pad detectors and readout electronics for a Compton camera

    CERN Document Server

    Studen, A; Clinthorne, N H; Czermak, A; Dulinski, W; Fuster, J A; Han, L; Jalocha, P; Kowal, M; Kragh, T; Lacasta, C; Llosa, G; Meier, D; Mikuz, M; Nygård, E; Park, S J; Roe, S; Rogers, W L; Sowicki, B; Weilhammer, P; Wilderman, S J; Yoshioka, K; Zhang, L

    2003-01-01

    Applications in nuclear medicine and bio-medical engineering may profit using a Compton camera for imaging distributions of radio-isotope labelled tracers in organs and tissues. These applications require detection of photons using thick position-sensitive silicon sensors with the highest possible energy and good spatial resolution. In this paper, research and development on silicon pad sensors and associated readout electronics for a Compton camera are presented. First results with low-noise, self-triggering VATAGP ASIC's are reported. The measured energy resolution was 1.1 keV FWHM at room temperature for the sup 2 sup 4 sup 1 Am photo-peak at 59.5 keV.

  2. The 2-79 keV X-ray spectrum of the circinus galaxy with NuSTAR, XMM-Newton, and Chandra: a fully compton-thick active galactic nucleus

    DEFF Research Database (Denmark)

    Arévalo, P.; Bauer, F. E.; Puccetti, S.

    2014-01-01

    The Circinus galaxy is one of the closest obscured active galactic nuclei (AGNs), making it an ideal target for detailed study. Combining archival Chandra and XMM-Newton data with new NuSTAR observations, we model the 2-79 keV spectrum to constrain the primary AGN continuum and to derive physical......-nuclear emission amounts to 18% of the nuclear flux in the Fe line region, but becomes comparable to the nuclear emission above 30 keV. The new analysis no longer supports a prominent transmitted AGN component in the observed band. We find that the nuclear spectrum is consistent with Compton scattering...

  3. Compton current detector

    International Nuclear Information System (INIS)

    Carvalho Campos, J.S. de.

    1984-01-01

    The project and construction of a Compton current detector, with cylindrical geometry using teflon as dielectric material; for electromagnetic radiation in range energy between 10 KeV and 2 MeV are described. The measurements of Compton current in teflon were obtained using an electrometer. The Compton current was promoted by photon flux proceeding from X ray sources (MG 150 Muller device) and gamma rays of 60 Co. The theory elaborated to explain the experimental results is shown. The calibration curves for accumulated charge and current in detector in function of exposition rates were obtained. (M.C.K.) [pt

  4. A Compton Imaging Prototype for Range Verification in Particle Therapy

    International Nuclear Information System (INIS)

    Golnik, C.; Hueso Gonzalez, F.; Kormoll, T.; Pausch, G.; Rohling, H.; Fiedler, F.; Heidel, K.; Schoene, S.; Sobiella, M.; Wagner, A.; Enghardt, W.

    2013-06-01

    During the 2012 AAPM Annual Meeting 33 percent of the delegates considered the range uncertainty in proton therapy as the main obstacle of becoming a mainstream treatment modality. Utilizing prompt gamma emission, a side product of particle tissue interaction, opens the possibility of in-beam dose verification, due to the direct correlation between prompt gamma emission and particle dose deposition. Compton imaging has proven to be a technique to measure three dimensional gamma emission profiles and opens the possibility of adaptive dose monitoring and treatment correction. We successfully built a Compton Imaging prototype, characterized the detectors and showed the imaging capability of the complete device. The major advantage of CZT detectors is the high energy resolution and the high spatial resolution, which are key parameters for Compton Imaging. However, our measurements at the proton beam accelerator facility KVI in Groningen (Netherlands) disclosed a spectrum of prompt gamma rays under proton irradiation up to 4.4 MeV. As CZT detectors of 5 mm thickness do not efficiently absorb photons in such energy ranges, another absorption, based on a Siemens LSO block detector is added behind CZT1. This setup provides a higher absorption probability of high energy photons. With a size of 5.2 cm x 5.2 cm x 2.0 cm, this scintillation detector further increases the angular acceptance of Compton scattered photons due to geometric size. (authors)

  5. A possible role for silicon microstrip detectors in nuclear medicine Compton imaging of positron emitters

    CERN Document Server

    Scannavini, M G; Royle, G J; Cullum, I; Raymond, M; Hall, G; Iles, G

    2002-01-01

    Collimation of gamma-rays based on Compton scatter could provide in principle high resolution and high sensitivity, thus becoming an advantageous method for the imaging of radioisotopes of clinical interest. A small laboratory prototype of a Compton camera is being constructed in order to initiate studies aimed at assessing the feasibility of Compton imaging of positron emitters. The design of the camera is based on the use of a silicon collimator consisting of a stack of double-sided, AC-coupled microstrip detectors (area 6x6 cm sup 2 , 500 mu m thickness, 128 channels/side). Two APV6 chips are employed for signal readout on opposite planes of each detector. This work presents the first results on the noise performance of the silicon strip detectors. Measurements of the electrical characteristics of the detector are also reported. On the basis of the measured noise, an angular resolution of approximately 5 deg. is predicted for the Compton collimator.

  6. A Chandra Observation of the Ultraluminous Infrared Galaxy IRAS 19254-7245 (The Superantennae): X-Ray Emission from the Compton-Thick Active Galactic Nucleus and the Diffuse Starburst

    Science.gov (United States)

    Jia, Jianjun; Ptak, Andrew; Heckman, Timothy M.; Braito, Valentina; Reeves, James

    2012-01-01

    We present a Chandra observation of IRAS 19254-7245, a nearby ultraluminous infrared galaxy also known as the Superantennae. The high spatial resolution of Chandra allows us to disentangle for the first time the diffuse starburst (SB) emission from the embedded Compton-thick active galactic nucleus (AGN) in the southern nucleus. No AGN activity is detected in the northern nucleus. The 2-10 keV spectrum of the AGN emission is fitted by a flat power law (TAU = 1.3) and an He-like Fe Kalpha line with equivalent width 1.5 keV, consistent with previous observations. The Fe K line profile could be resolved as a blend of a neutral 6.4 keV line and an ionized 6.7 keV (He-like) or 6.9 keV (H-like) line. Variability of the neutral line is detected compared with the previous XMM-Newton and Suzaku observations, demonstrating the compact size of the iron line emission. The spectrum of the galaxy-scale extended emission excluding the AGN and other bright point sources is fitted with a thermal component with a best-fit kT of approximately 0.8 keV. The 2-10 keV luminosity of the extended emission is about one order of magnitude lower than that of the AGN. The basic physical and structural properties of the extended emission are fully consistent with a galactic wind being driven by the SB. A candidate ultraluminous X-ray source is detected 8 south of the southern nucleus. The 0.3 - 10 keV luminosity of this off-nuclear point source is approximately 6 x 10(exp 40) erg per second if the emission is isotropic and the source is associated with the Superantennae.

  7. Fast sampling algorithm for the simulation of photon Compton scattering

    International Nuclear Information System (INIS)

    Brusa, D.; Salvat, F.

    1996-01-01

    A simple algorithm for the simulation of Compton interactions of unpolarized photons is described. The energy and direction of the scattered photon, as well as the active atomic electron shell, are sampled from the double-differential cross section obtained by Ribberfors from the relativistic impulse approximation. The algorithm consistently accounts for Doppler broadening and electron binding effects. Simplifications of Ribberfors' formula, required for efficient random sampling, are discussed. The algorithm involves a combination of inverse transform, composition and rejection methods. A parameterization of the Compton profile is proposed from which the simulation of Compton events can be performed analytically in terms of a few parameters that characterize the target atom, namely shell ionization energies, occupation numbers and maximum values of the one-electron Compton profiles. (orig.)

  8. Compton radiography, 3. Compton scinti-tomography of the chest diseases

    Energy Technology Data Exchange (ETDEWEB)

    Okuyama, S; Sera, K; Shishido, F; Fukuda, H [Tohoku Univ., Sendai (Japan). Research Inst. for Tuberculosis, Leprosy and Cancer; Mishina, H

    1977-10-01

    The compton radiography aims at collection of depth information by recording with a scinticamera those Compton rays that have resulted from scattering of a monoenergetic gamma beam by a volume of interest. Appreciably clear clinical scinti-tomograms were obtained of the chest wall, and intrathoracic structures such as the lungs, intrapulmonary pathologies, and mediastinum. This was achieved without any computer assistance for image reconstruction such as those in the case of XCT. Apparently, suitable corrections of the attenuations of the primary monoenergetic gamma rays and secondary Compton rays would greatly improve the image quality, and imaging time and radiation exposure as well. This technic is simple in principle, relatively cheap, and yet prospective of development of stereoptic fluoroscopy that would be extremely helpful in guiding such procedures as visceral biopsies.

  9. Dispersion relations in real and virtual Compton scattering

    International Nuclear Information System (INIS)

    Drechsel, D.; Pasquini, B.; Vanderhaeghen, M.

    2003-01-01

    A unified presentation is given on the use of dispersion relations in the real and virtual Compton scattering processes off the nucleon. The way in which dispersion relations for Compton scattering amplitudes establish connections between low energy nucleon structure quantities, such as polarizabilities or anomalous magnetic moments, and the nucleon excitation spectrum is reviewed. We discuss various sum rules for forward real and virtual Compton scattering, such as the Gerasimov-Drell-Hearn sum rule and its generalizations, the Burkhardt-Cottingham sum rule, as well as sum rules for forward nucleon polarizabilities, and review their experimental status. Subsequently, we address the general case of real Compton scattering (RCS). Various types of dispersion relations for RCS are presented as tools for extracting nucleon polarizabilities from the RCS data. The information on nucleon polarizabilities gained in this way is reviewed and the nucleon structure information encoded in these quantities is discussed. The dispersion relation formalism is then extended to virtual Compton scattering (VCS). The information on generalized nucleon polarizabilities extracted from recent VCS experiments is described, along with its interpretation in nucleon structure models. As a summary, the physics content of the existing data is discussed and some perspectives for future theoretical and experimental activities in this field are presented

  10. A method for determination mass absorption coefficient of gamma rays by Compton scattering.

    Science.gov (United States)

    El Abd, A

    2014-12-01

    A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Inverse Compton gamma-rays from pulsars

    International Nuclear Information System (INIS)

    Morini, M.

    1983-01-01

    A model is proposed for pulsar optical and gamma-ray emission where relativistic electrons beams: (i) scatter the blackbody photons from the polar cap surface giving inverse Compton gamma-rays and (ii) produce synchrotron optical photons in the light cylinder region which are then inverse Compton scattered giving other gamma-rays. The model is applied to the Vela pulsar, explaining the first gamma-ray pulse by inverse Compton scattering of synchrotron photons near the light cylinder and the second gamma-ray pulse partly by inverse Compton scattering of synchrotron photons and partly by inverse Compton scattering of the thermal blackbody photons near the star surface. (author)

  12. Weak Hard X-Ray Emission from Two Broad Absorption Line Quasars Observed with NuStar: Compton-Thick Absorption or Intrinsic X-Ray Weakness?

    Science.gov (United States)

    Luo, B.; Brandt, W. N.; Alexander, D. M.; Harrison, F. A.; Stern, D.; Bauer, F. E.; Boggs, S. E.; Christensen, F. E.; Comastri, A.; Craig, W. W..; hide

    2013-01-01

    We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain approx. or equal to 400-600 hard X-ray (is greater than or equal to 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed N(sub H) is less than or equal to 10(exp24) cm(exp-2). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N(sub H) 7 × 10(exp 24) cm(exp-2) if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe Ka line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

  13. WEAK HARD X-RAY EMISSION FROM TWO BROAD ABSORPTION LINE QUASARS OBSERVED WITH NuSTAR: COMPTON-THICK ABSORPTION OR INTRINSIC X-RAY WEAKNESS?

    Energy Technology Data Exchange (ETDEWEB)

    Luo, B.; Brandt, W. N. [Department of Astronomy and Astrophysics, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16802 (United States); Alexander, D. M.; Hickox, R. [Department of Physics, Durham University, South Road, Durham DH1 3LE (United Kingdom); Harrison, F. A.; Fuerst, F.; Grefenstette, B. W.; Madsen, K. K. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Stern, D. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Bauer, F. E. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago 22 (Chile); Boggs, S. E.; Craig, W. W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E. [DTU Space-National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, A. [INAF-Osservatorio Astronomico di Bologna, Via Ranzani 1, I-40127 Bologna (Italy); Fabian, A. C. [Institute of Astronomy, Madingley Road, Cambridge CB3 0HA (United Kingdom); Farrah, D. [Department of Physics, Virginia Tech, Blacksburg, VA 24061 (United States); Fiore, F. [Osservatorio Astronomico di Roma, via Frascati 33, I-00040 Monteporzio Catone (Italy); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Matt, G. [Dipartimento di Matematica e Fisica, Universita degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Ogle, P. [IPAC, California Institute of Technology, Mail Code 220-6, Pasadena, CA 91125 (United States); and others

    2013-08-01

    We present Nuclear Spectroscopic Telescope Array (NuSTAR) hard X-ray observations of two X-ray weak broad absorption line (BAL) quasars, PG 1004+130 (radio loud) and PG 1700+518 (radio quiet). Many BAL quasars appear X-ray weak, probably due to absorption by the shielding gas between the nucleus and the accretion-disk wind. The two targets are among the optically brightest BAL quasars, yet they are known to be significantly X-ray weak at rest-frame 2-10 keV (16-120 times fainter than typical quasars). We would expect to obtain Almost-Equal-To 400-600 hard X-ray ({approx}> 10 keV) photons with NuSTAR, provided that these photons are not significantly absorbed (N{sub H} {approx}< 10{sup 24} cm{sup -2}). However, both BAL quasars are only detected in the softer NuSTAR bands (e.g., 4-20 keV) but not in its harder bands (e.g., 20-30 keV), suggesting that either the shielding gas is highly Compton-thick or the two targets are intrinsically X-ray weak. We constrain the column densities for both to be N{sub H} Almost-Equal-To 7 Multiplication-Sign 10{sup 24} cm{sup -2} if the weak hard X-ray emission is caused by obscuration from the shielding gas. We discuss a few possibilities for how PG 1004+130 could have Compton-thick shielding gas without strong Fe K{alpha} line emission; dilution from jet-linked X-ray emission is one likely explanation. We also discuss the intrinsic X-ray weakness scenario based on a coronal-quenching model relevant to the shielding gas and disk wind of BAL quasars. Motivated by our NuSTAR results, we perform a Chandra stacking analysis with the Large Bright Quasar Survey BAL quasar sample and place statistical constraints upon the fraction of intrinsically X-ray weak BAL quasars; this fraction is likely 17%-40%.

  14. Towards A Complete Census of the Compton-thick AGN population and the NH Distribution of AGN in the Local Universe.

    Science.gov (United States)

    Annuar, A.

    2015-09-01

    We present updated results from an ongoing project to establish the most unbiased census of the Compton- thick active galactic nucleus (CTAGN) population and the intrinsic column density (NH) distribution of the overall AGN population in the local universe, using a sample of mid-infrared (mid-IR) selected AGN within 15 Mpc. We find that 20% of the AGN in the sample are bona-fide CTAGN based upon hard X-ray studies (E > 10 keV). More candidates are then selected using multiwavelength techniques, i.e. mid-IR:X-ray and optical [OIII]5007:X-ray flux ratios. Based on these analyses along with evidence from previous literature, we initially find a further 25% of potential candidates. We then observed two of these candidates, NGC 5643 and NGC 3486, using NuSTAR and is able to confirm the former as a CTAGN and rule out the latter as an obscured AGN. This constrains the total CTAGN population in the sample to 25-40%, though it could potentially be as high as 65% accounting for those that still lack data. Finally, we use these results to estimate the intrinsic NH distribution of the local AGN population. Two more of our CTAGN candidates are scheduled to be observed by NuSTAR, bringing the completeness of hard X-ray energy data of the sample to 65%. This work provides a well-defined local benchmark for AGN unification studies.

  15. A method for determination mass absorption coefficient of gamma rays by Compton scattering

    International Nuclear Information System (INIS)

    El Abd, A.

    2014-01-01

    A method was proposed for determination mass absorption coefficient of gamma rays for compounds, alloys and mixtures. It is based on simulating interaction processes of gamma rays with target elements having atomic numbers from Z=1 to Z=92 using the MCSHAPE software. Intensities of Compton scattered gamma rays at saturation thicknesses and at a scattering angle of 90° were calculated for incident gamma rays of different energies. The obtained results showed that the intensity of Compton scattered gamma rays at saturations and mass absorption coefficients can be described by mathematical formulas. These were used to determine mass absorption coefficients for compound, alloys and mixtures with the knowledge of their Compton scattered intensities. The method was tested by calculating mass absorption coefficients for some compounds, alloys and mixtures. There is a good agreement between obtained results and calculated ones using WinXom software. The advantages and limitations of the method were discussed. - Highlights: • Compton scattering of γ−rays was used for determining mass absorption coefficient. • Scattered intensities were determined by the MCSHAPE software. • Mass absorption coefficients were determined for some compounds, mixtures and alloys. • Mass absorption coefficients were calculated by Winxcom software. • Good agreements were found between determined and calculated results

  16. Thermal Comptonization in standard accretion disks

    International Nuclear Information System (INIS)

    Maraschi, L.; Molendi, S.

    1990-01-01

    The standard model of an accretion disk is considered. The temperature in the inner region is computed assuming that the radiated power derives from Comptonized photons, produced in a homogeneous single-temperature plasma, supported by radiation pressure. The photon production mechanisms are purely thermal, including ion-electron bremsstrahlung, bound-free and bound-bound processes, and e-e bremsstrahlung. Pair production is not included, which limits the validity of the treatment to kT less than 60 keV. Three different approximations for the effects of Comptonization on the energy loss are used, yielding temperatures which agree within 50 percent. The maximum temperature is very sensitive to the accretion rate and viscosity parameters, ranging, for a 10 to the 8th solar mass black hole, between 0.1 and 50 keV for m between 0.1 and 1 and alpha between 0.1 and 1 and, for a 10-solar-mass black hole, between 0.6 and 60 keV for m between 0.1 and 0.9 and alpha between 0.1 and 0.5. For high viscosity and accretion rates, the emission spectra show a flat component following a peak corresponding to the temperature of the innermost optically thick annulus. 28 refs

  17. High-resolution Compton cameras based on Si/CdTe double-sided strip detectors

    International Nuclear Information System (INIS)

    Odaka, Hirokazu; Ichinohe, Yuto; Takeda, Shin'ichiro; Fukuyama, Taro; Hagino, Koichi; Saito, Shinya; Sato, Tamotsu; Sato, Goro; Watanabe, Shin; Kokubun, Motohide; Takahashi, Tadayuki; Yamaguchi, Mitsutaka

    2012-01-01

    We have developed a new Compton camera based on silicon (Si) and cadmium telluride (CdTe) semiconductor double-sided strip detectors (DSDs). The camera consists of a 500-μm-thick Si-DSD and four layers of 750-μm-thick CdTe-DSDs all of which have common electrode configuration segmented into 128 strips on each side with pitches of 250μm. In order to realize high angular resolution and to reduce size of the detector system, a stack of DSDs with short stack pitches of 4 mm is utilized to make the camera. Taking advantage of the excellent energy and position resolutions of the semiconductor devices, the camera achieves high angular resolutions of 4.5° at 356 keV and 3.5° at 662 keV. To obtain such high resolutions together with an acceptable detection efficiency, we demonstrate data reduction methods including energy calibration using Compton scattering continuum and depth sensing in the CdTe-DSD. We also discuss imaging capability of the camera and show simultaneous multi-energy imaging.

  18. Environmental radioactivity measurements Using a compton suppression spectrometer

    International Nuclear Information System (INIS)

    Sharshar, T.; Elnimr, T.

    1998-01-01

    The natural and artificial radioactivities of some environmental samples such as soil and vegetables have been studied through gamma-ray spectroscopy with a new constructed compton suppression spectrometer (CSS). The spectrometer consists of a 10% p-type HPGe detector as a main detector, an annular NE-102 A plastic scintillator as a guard detector, and a fast-slow coincidence system employing standard electronic modules for anti-compton operation. This study shows that CSS is a powerful tool for measuring the low level activities of environmental samples

  19. A deep NuSTAR observation of M51: Investigating its Compton-thick nucleus, LINER companion and ULXs above 10 keV

    Science.gov (United States)

    Brightman, Murray; Annuar, Ady; Alexander, David M.; Earnshaw, Hannah; Gandhi, Poshak; Hornschemeier, Ann E.; Lehmer, Bret; Ptak, Andrew; Rangelov, Blagoy; Roberts, Tim P.; Stern, Daniel; Zezas, Andreas

    2017-08-01

    We present the results from a deep 200ks observation of M51 with NuSTAR. This observation was taken simultaneously with Chandra to provide soft-X-ray-coverage as well as to resolve the different point sources. We detect the Compton-thick nucleus of M51a, the LINER nucleus of M51b and several ultraluminous X-ray sources located in the galaxies above 10 keV. From X-ray torus modeling, we find that the covering factor of the torus in the nucleus of M51a is ~40% and supports a decline in the obscured fration at low X-ray luminosities. We find that the X-ray spectrum of the intermediate mass black hole candidate, ULX-7, is consistent with a power-law up to high energies, supporting its IMBH status. We further resolve the nucleus of M51b into two X-ray sources with Chandra, and measure its X-ray luminosity.

  20. Compton Operator in Quantum Electrodynamics

    International Nuclear Information System (INIS)

    Garcia, Hector Luna; Garcia, Luz Maria

    2015-01-01

    In the frame in the quantum electrodynamics exist four basic operators; the electron self-energy, vacuum polarization, vertex correction, and the Compton operator. The first three operators are very important by its relation with renormalized and Ward identity. However, the Compton operator has equal importance, but without divergence, and little attention has been given it. We have calculated the Compton operator and obtained the closed expression for it in the frame of dimensionally continuous integration and hypergeometric functions

  1. LIFTING THE VEIL ON OBSCURED ACCRETION: ACTIVE GALACTIC NUCLEI NUMBER COUNTS AND SURVEY STRATEGIES FOR IMAGING HARD X-RAY MISSIONS

    International Nuclear Information System (INIS)

    Ballantyne, D. R.; Draper, A. R.; Madsen, K. K.; Rigby, J. R.; Treister, E.

    2011-01-01

    Finding and characterizing the population of active galactic nuclei (AGNs) that produces the X-ray background (XRB) is necessary to connect the history of accretion to observations of galaxy evolution at longer wavelengths. The year 2012 will see the deployment of the first hard X-ray imaging telescope which, through deep extragalactic surveys, will be able to measure the AGN population at the energies where the XRB peaks (∼20-30 keV). Here, we present predictions of AGN number counts in three hard X-ray bandpasses: 6-10 keV, 10-30 keV, and 30-60 keV. Separate predictions are presented for the number counts of Compton thick AGNs, the most heavily obscured active galaxies. The number counts are calculated for five different models of the XRB that differ in the assumed hard X-ray luminosity function, the evolution of the Compton thick AGNs, and the underlying AGN spectral model. The majority of the hard X-ray number counts will be Compton thin AGNs, but there is a greater than tenfold increase in the Compton thick number counts from the 6-10 keV to the 10-30 keV band. The Compton thick population shows enough variation that a hard X-ray number counts measurement will constrain the models. The computed number counts are used to consider various survey strategies for the NuSTAR mission, assuming a total exposure time of 6.2 Ms. We find that multiple surveys will allow a measurement of Compton thick evolution. The predictions presented here should be useful for all future imaging hard X-ray missions.

  2. Angular distribution of 662keV multiply-Compton scattered gamma rays in copper

    International Nuclear Information System (INIS)

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

    2007-01-01

    The angular distribution of multiple Compton scattering of 662keV gamma photons, obtained from six Curie 137 Cs source, incident on copper scatterer of varying thickness is studied experimentally in both the forward and backward hemispheres. The scattered photons are detected by a 51mmx51mm NaI(Tl) scintillation detector. The full-energy peak corresponding to singly scattered events is reconstructed analytically. We observe that the numbers of multiply scattered events, having same energy as in the singly scattered distribution, first increases with increase in target thickness and then saturate. The optimum thickness at which the multiply scattered events saturate is determined at different scattering angles

  3. Compton scattering revisited

    International Nuclear Information System (INIS)

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

    2010-01-01

    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 Suric 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

  4. High-repetition intra-cavity source of Compton radiation

    International Nuclear Information System (INIS)

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

    2014-01-01

    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. (paper)

  5. A dual purpose Compton suppression spectrometer

    CERN Document Server

    Parus, J; Raab, W; Donohue, D

    2003-01-01

    A gamma-ray spectrometer with a passive and an active shield is described. It consists of a HPGe coaxial detector of 42% efficiency and 4 NaI(Tl) detectors. The energy output pulses of the Ge detector are delivered into the 3 spectrometry chains giving the normal, anti- and coincidence spectra. From the spectra of a number of sup 1 sup 3 sup 7 Cs and sup 6 sup 0 Co sources a Compton suppression factor, SF and a Compton reduction factor, RF, as the parameters characterizing the system performance, were calculated as a function of energy and source activity and compared with those given in literature. The natural background is reduced about 8 times in the anticoincidence mode of operation, compared to the normal spectrum which results in decreasing the detection limits for non-coincident gamma-rays up to a factor of 3. In the presence of other gamma-ray activities, in the range from 5 to 11 kBq, non- and coincident, the detection limits can be decreased for some nuclides by a factor of 3 to 5.7.

  6. X-ray Compton line scan tomography

    Energy Technology Data Exchange (ETDEWEB)

    Kupsch, Andreas; Lange, Axel; Jaenisch, Gerd-Ruediger [Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin (Germany). Fachgruppe 8.5 - Mikro-ZfP; Hentschel, Manfred P. [Technische Univ. Berlin (Germany); Kardjilov, Nikolay; Markoetter, Henning; Hilger, Andre; Manke, Ingo [Helmholtz-Zentrum Berlin (HZB) (Germany); Toetzke, Christian [Potsdam Univ. (Germany)

    2015-07-01

    The potentials of incoherent X-ray scattering (Compton) computed tomography (CT) are investigated. The imaging of materials of very different atomic number or density at once is generally a perpetual challenge for X-ray tomography or radiography. In a basic laboratory set-up for simultaneous perpendicular Compton scattering and direct beam attenuation tomography are conducted by single channel photon counting line scans. This results in asymmetric distortions of the projection profiles of the scattering CT data set. In a first approach, corrections of Compton scattering data by taking advantage of rotational symmetry yield tomograms without major geometric artefacts. A cylindrical sample composed of PE, PA, PVC, glass and wood demonstrates similar Compton contrast for all the substances, while the conventional absorption tomogram only reveals the two high order materials. Comparison to neutron tomography reveals astonishing similarities except for the glass component (without hydrogen). Therefore, Compton CT offers the potential to replace neutron tomography, which requires much more efforts.

  7. Compton scattering revisited

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, R.H., E-mail: rpratt@pitt.ed [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); LaJohn, L.A., E-mail: lal18@pitt.ed [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15260 (United States); Florescu, V., E-mail: flor@barutu.fizica.unibuc.r [Centre for Advanced Quantum Physics, University of Bucharest, MG-11 Bucharest-Magurele, 077125 Magurele (Romania); Suric, T., E-mail: suric@irb.h [R. Boskovic Institute, Bijenicka 54, 10000 Zagreb (Croatia); Chatterjee, B.K., E-mail: barun_k_chatterjee@yahoo.co [Department of Physics, Bose Institute, Kolkata 700009 (India); Roy, S.C., E-mail: suprakash.roy@gmail.co [Department of Physics, Bose Institute, Kolkata 700009 (India)

    2010-02-15

    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 Suric 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{sup -}>.A{sup -}> effects come into play. (4) Most relativistic effects, except at low

  8. Energy distribution of 0. 279 MeV gamma rays Compton scattered from bound electrons

    Energy Technology Data Exchange (ETDEWEB)

    Singh, B; Singh, P; Singh, G; Ghumman, B S

    1984-11-01

    Energy and intensity distribution of 0.279 MeV gamma rays Compton scattered from K-shell electrons of tantalum is measured at scattering angle of 70deg. The experimental results are compared with the available theoretical data. Spectral distribution is also obtained as a function of scatterer thickness to account for the contribution of false events. 13 refs.

  9. The Compton generator revisited

    Science.gov (United States)

    Siboni, S.

    2014-09-01

    The Compton generator, introduced in 1913 by the US physicist A H Compton as a relatively simple device to detect the Earth's rotation with respect to the distant stars, is analyzed and discussed in a general perspective. The paper introduces a generalized definition of the generator, emphasizing the special features of the original apparatus, and provides a suggestive interpretation of the way the device works. To this end, an intriguing electromagnetic analogy is developed, which turns out to be particularly useful in simplifying the calculations. Besides the more extensive description of the Compton generator in itself, the combined use of concepts and methods coming from different fields of physics, such as particle dynamics in moving references frames, continuum mechanics and electromagnetism, may be of interest to both teachers and graduate students.

  10. Characterization of a Compton suppression system and the applicability of Poisson statistics

    International Nuclear Information System (INIS)

    Nicholson, G.; Landsberger, S.; Welch, L.

    2008-01-01

    The Compton suppression system (CSS) has been thoroughly characterized at the University of Texas' Nuclear Engineering Teaching Laboratory (NETL). Effects of dead-time, sample displacement from primary detector, and primary energy detector position relative to the active shield detector have been measured and analyzed. Also, the applicability of Poisson counting statistics to Compton suppression spectroscopy has been evaluated. (author)

  11. A simple scanner for Compton tomography

    CERN Document Server

    Cesareo, R; Brunetti, A; Golosio, B; Castellano, A

    2002-01-01

    A first generation CT-scanner was designed and constructed to carry out Compton images. This CT-scanner is composed of a 80 kV, 5 mA X-ray tube and a NaI(Tl) X-ray detector; the tube is strongly collimated, generating a X-ray beam of 2 mm diameter, whilst the detector is not collimated to collect Compton photons from the whole irradiated cylinder. The performances of the equipment were tested contemporaneous transmission and Compton images.

  12. Nuclear Compton scattering

    International Nuclear Information System (INIS)

    Christillin, P.

    1986-01-01

    The theory of nuclear Compton scattering is reformulated with explicit consideration of both virtual and real pionic degrees of freedom. The effects due to low-lying nuclear states, to seagull terms, to pion condensation and to the Δ dynamics in the nucleus and their interplay in the different energy regions are examined. It is shown that all corrections to the one-body terms, of diffractive behaviour determined by the nuclear form factor, have an effective two-body character. The possibility of using Compton scattering as a complementary source of information about nuclear dynamics is restressed. (author)

  13. Development of a Compton camera for online monitoring and dosimetry of laser-accelerated proton beams

    Energy Technology Data Exchange (ETDEWEB)

    Thirolf, Peter G.; Lang, Christian; Aldawood, Saad; Parodi, Katia [LMU Muenchen (Germany); Habs, Dietrich [LMU Muenchen (Germany); MPI fuer Quantenoptik, Garching (Germany); Maier, Ludwig [TU Muenchen (Germany)

    2013-07-01

    A Compton camera is presently under construction in Garching, designed for monitoring and dosimetry of laser-accelerated protons for bio-medical applications via position-resolved prompt γ-ray detection. When ion beams suitable for hadron therapy (protons, carbon ions) interact with tissue (or tissue-equivalent plastic or water phantoms), nuclear reactions induce prompt γ rays that can be utilized, e.g., to verify the ion beam range (i.e. monitor the Bragg peak position) by exploiting the Compton scattering kinematics of these photons. Our Compton camera (formed by a combination of scatter and absorber detector) consists of a stack of six double-sided Si-strip detectors (50 x 50 mm{sup 2}, 0.5 mm thick, 128 strips/side, pitch 390 μm) acting as scatterers, while the absorber is formed by a LaBr{sub 3} scintillator crystal (50 x 50 x 30 mm{sup 3}), read out by a (8 x 8) pixelated multi-anode PMT. Simulation results for design specifications and expected values of resolution and efficiency are presented, as well as the status of the prototype presently under construction.

  14. A New Compton-thick AGN in our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR

    Science.gov (United States)

    Annuar, A.; Alexander, D. M.; Gandhi, P.; Lansbury, G. B.; Asmus, D.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; Brightman, M.; Christensen, F. E.; Craig, W. W.; Farrah, D.; Goulding, A. D.; Hailey, C. J.; Harrison, F. A.; Koss, M. J.; LaMassa, S. M.; Murray, S. S.; Ricci, C.; Rosario, D. J.; Stanley, F.; Stern, D.; Zhang, W.

    2017-02-01

    NGC 1448 is one of the nearest luminous galaxies (L 8-1000μm > 109 L ⊙) to ours (z = 0.00390), and yet the active galactic nucleus (AGN) it hosts was only recently discovered, in 2009. In this paper, we present an analysis of the nuclear source across three wavebands: mid-infrared (MIR) continuum, optical, and X-rays. We observed the source with the Nuclear Spectroscopic Telescope Array (NuSTAR), and combined these data with archival Chandra data to perform broadband X-ray spectral fitting (≈0.5-40 keV) of the AGN for the first time. Our X-ray spectral analysis reveals that the AGN is buried under a Compton-thick (CT) column of obscuring gas along our line of sight, with a column density of N H(los) ≳ 2.5 × 1024 cm-2. The best-fitting torus models measured an intrinsic 2-10 keV luminosity of L {}2-10,{int} = (3.5-7.6) × 1040 erg s-1, making NGC 1448 one of the lowest luminosity CTAGNs known. In addition to the NuSTAR observation, we also performed optical spectroscopy for the nucleus in this edge-on galaxy using the European Southern Observatory New Technology Telescope. We re-classify the optical nuclear spectrum as a Seyfert on the basis of the Baldwin-Philips-Terlevich diagnostic diagrams, thus identifying the AGN at optical wavelengths for the first time. We also present high spatial resolution MIR observations of NGC 1448 with Gemini/T-ReCS, in which a compact nucleus is clearly detected. The absorption-corrected 2-10 keV luminosity measured from our X-ray spectral analysis agrees with that predicted from the optical [O III]λ5007 Å emission line and the MIR 12 μm continuum, further supporting the CT nature of the AGN.

  15. Signature of inverse Compton emission from blazars

    Science.gov (United States)

    Gaur, Haritma; Mohan, Prashanth; Wierzcholska, Alicja; Gu, Minfeng

    2018-01-01

    Blazars are classified into high-, intermediate- and low-energy-peaked sources based on the location of their synchrotron peak. This lies in infra-red/optical to ultra-violet bands for low- and intermediate-peaked blazars. The transition from synchrotron to inverse Compton emission falls in the X-ray bands for such sources. We present the spectral and timing analysis of 14 low- and intermediate-energy-peaked blazars observed with XMM-Newton spanning 31 epochs. Parametric fits to X-ray spectra help constrain the possible location of transition from the high-energy end of the synchrotron to the low-energy end of the inverse Compton emission. In seven sources in our sample, we infer such a transition and constrain the break energy in the range 0.6-10 keV. The Lomb-Scargle periodogram is used to estimate the power spectral density (PSD) shape. It is well described by a power law in a majority of light curves, the index being flatter compared to general expectation from active galactic nuclei, ranging here between 0.01 and 1.12, possibly due to short observation durations resulting in an absence of long-term trends. A toy model involving synchrotron self-Compton and external Compton (EC; disc, broad line region, torus) mechanisms are used to estimate magnetic field strength ≤0.03-0.88 G in sources displaying the energy break and infer a prominent EC contribution. The time-scale for variability being shorter than synchrotron cooling implies steeper PSD slopes which are inferred in these sources.

  16. Critical review of Compton imaging

    International Nuclear Information System (INIS)

    Guzzardi, R.; Licitra, G.

    1987-01-01

    This paper reviews the basic aspects, problems, and applications of Compton imaging including those related to nonmedical applications. The physics and technology at the base of this specific methodology are analyzed and the relative differences and merits with respect to other imaging techniques, using ionizing radiations, are reviewed. The basic Compton imaging approaches, i.e., point-by-point, line-by-line, and plane-by-plane, are analyzed. Specifically, physical design and technological aspects are reviewed and discussed. Furthermore, the most important clinical applications of the different methods are presented and discussed. Finally, possibilities and applications of the Compton imaging method to other nonmedical fields, as in the case of the important area of object defects recognition, are analyzed and reviewed. 56 references

  17. Inverse comptonization vs. thermal synchrotron

    International Nuclear Information System (INIS)

    Fenimore, E.E.; Klebesadel, R.W.; Laros, J.G.

    1983-01-01

    There are currently two radiation mechanisms being considered for gamma-ray bursts: thermal synchrotron and inverse comptonization. They are mutually exclusive since thermal synchrotron requires a magnetic field of approx. 10 12 Gauss whereas inverse comptonization cannot produce a monotonic spectrum if the field is larger than 10 11 and is too inefficient relative to thermal synchrotron unless the field is less than 10 9 Gauss. Neither mechanism can explain completely the observed characteristics of gamma-ray bursts. However, we conclude that thermal synchrotron is more consistent with the observations if the sources are approx. 40 kpc away whereas inverse comptonization is more consistent if they are approx. 300 pc away. Unfortunately, the source distance is still not known and, thus, the radiation mechanism is still uncertain

  18. Fast image reconstruction for Compton camera using stochastic origin ensemble approach.

    Science.gov (United States)

    Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

    2011-01-01

    will be much larger when full Compton camera system model, including resolution recovery, is implemented and realistic Compton camera geometries are used. It was also shown in this article that while correctly reconstructing the relative distribution of the activity in the object, the SOE algorithm tends to underestimate the intensity values and increase variance in the images; improvements to the SOE reconstruction algorithm will be considered in future work.

  19. Maximum Likelihood Compton Polarimetry with the Compton Spectrometer and Imager

    Energy Technology Data Exchange (ETDEWEB)

    Lowell, A. W.; Boggs, S. E; Chiu, C. L.; Kierans, C. A.; Sleator, C.; Tomsick, J. A.; Zoglauer, A. C. [Space Sciences Laboratory, University of California, Berkeley (United States); Chang, H.-K.; Tseng, C.-H.; Yang, C.-Y. [Institute of Astronomy, National Tsing Hua University, Taiwan (China); Jean, P.; Ballmoos, P. von [IRAP Toulouse (France); Lin, C.-H. [Institute of Physics, Academia Sinica, Taiwan (China); Amman, M. [Lawrence Berkeley National Laboratory (United States)

    2017-10-20

    Astrophysical polarization measurements in the soft gamma-ray band are becoming more feasible as detectors with high position and energy resolution are deployed. Previous work has shown that the minimum detectable polarization (MDP) of an ideal Compton polarimeter can be improved by ∼21% when an unbinned, maximum likelihood method (MLM) is used instead of the standard approach of fitting a sinusoid to a histogram of azimuthal scattering angles. Here we outline a procedure for implementing this maximum likelihood approach for real, nonideal polarimeters. As an example, we use the recent observation of GRB 160530A with the Compton Spectrometer and Imager. We find that the MDP for this observation is reduced by 20% when the MLM is used instead of the standard method.

  20. Commissioning of the scatter component of a Compton camera consisting of a stack of Si strip detectors

    Energy Technology Data Exchange (ETDEWEB)

    Liprandi, S.; Marinsek, T.; Bortfeldt, J.; Lang, C.; Lutter, R.; Dedes, G.; Parodi, K.; Thirolf, P.G. [LMU Munich, Garching (Germany); Aldawood, S. [LMU Munich, Garching (Germany); King Saud University, Riyadh (Saudi Arabia); Maier, L.; Gernhaeuser, R. [TU Munich, Garching (Germany); Kolff, H. van der [LMU Munich, Garching (Germany); TU Delft (Netherlands); Castelhano, I. [LMU Munich, Garching (Germany); University of Lisbon, Lisbon (Portugal); Schaart, D.R. [TU Delft (Netherlands)

    2015-07-01

    At LMU Munich in Garching a Compton camera is presently being developed aiming at the range verification of proton (or ion) beams for hadron therapy via imaging of prompt γ rays from nuclear reactions in the tissue. The poster presentation focuses on the characterization of the scatter component of the Compton camera, consisting of a stack of six double-sided Si strip detectors (50 x 50 mm{sup 2}, 0.5 mm thick, 128 strips/side). The overall 1536 electronics channels are processed by a readout system based on the GASSIPLEX ASIC chip, feeding into a VME-based data acquisition system. The status of the offline and online characterization studies is presented.

  1. Neutron Compton scattering from selectively deuterated acetanilide

    Science.gov (United States)

    Wanderlingh, U. N.; Fielding, A. L.; Middendorf, H. D.

    With the aim of developing the application of neutron Compton scattering (NCS) to molecular systems of biophysical interest, we are using the Compton spectrometer EVS at ISIS to characterize the momentum distribution of protons in peptide groups. In this contribution we present NCS measurements of the recoil peak (Compton profile) due to the amide proton in otherwise fully deuterated acetanilide (ACN), a widely studied model system for H-bonding and energy transfer in biomolecules. We obtain values for the average width of the potential well of the amide proton and its mean kinetic energy. Deviations from the Gaussian form of the Compton profile, analyzed on the basis of an expansion due to Sears, provide data relating to the Laplacian of the proton potential.

  2. Proceedings of the Fourth Compton Symposium. Proceedings

    International Nuclear Information System (INIS)

    Dermer, C.D.; Strickman, M.S.; Kurfess, J.D.

    1997-01-01

    These proceedings represent the papers presented at the Fourth Compton Symposium held in Williamsburg, Virginia in April, 1997. This symposium gives the latest development in gamma ray astronomy and summarizes the results obtained by the Compton Gamma Ray Observatory. One of the missions of the Observatory has been the study of physical processes taking place in the most dynamic sites in the Universe, including supernovae, novae, pulsars, black holes, active galaxies, and gamma-ray bursts. The energies covered range from hard X-ray to gamma-ray regions from 15 KeV to 30 GeV. The Burst and Transient Experiment (BASTE) measures brightness variations in gamma-ray bursts and solar flares. The Oriented Scintillation Spectroscopy Experiment (OSSE), measures spectral output of astrophysical sources in the 0.05 to 10 MeV range. The Imaging Compton Telescope (COMPTEL) detects gamma-rays and performs sky survey in the energy range 1 to 30 MeV. The Energetic Gamma Ray Experiment Telescope (EGRET) covers the broadest energy range from 20 MeV to 30 GeV. The papers presented result from all of the above. There were 249 papers presented and out of these, 6 have been abstracted for the Energy, Science and Technology database

  3. Induced Compton-scattering effects in radiation-transport approximations

    International Nuclear Information System (INIS)

    Gibson, D.R. Jr.

    1982-02-01

    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

  4. Compton recoil electron tracking with silicon strip detectors

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  5. Using Compton scattering for random coincidence rejection

    International Nuclear Information System (INIS)

    Kolstein, M.; Chmeissani, M.

    2016-01-01

    The Voxel Imaging PET (VIP) project presents a new approach for the design of nuclear medicine imaging devices by using highly segmented pixel CdTe sensors. CdTe detectors can achieve an energy resolution of ≈ 1% FWHM at 511 keV and can be easily segmented into submillimeter sized voxels for optimal spatial resolution. These features help in rejecting a large part of the scattered events from the PET coincidence sample in order to obtain high quality images. Another contribution to the background are random events, i.e., hits caused by two independent gammas without a common origin. Given that 60% of 511 keV photons undergo Compton scattering in CdTe (i.e. 84% of all coincidence events have at least one Compton scattering gamma), we present a simulation study on the possibility to use the Compton scattering information of at least one of the coincident gammas within the detector to reject random coincidences. The idea uses the fact that if a gamma undergoes Compton scattering in the detector, it will cause two hits in the pixel detectors. The first hit corresponds to the Compton scattering process. The second hit shall correspond to the photoelectric absorption of the remaining energy of the gamma. With the energy deposition of the first hit, one can calculate the Compton scattering angle. By measuring the hit location of the coincident gamma, we can construct the geometric angle, under the assumption that both gammas come from the same origin. Using the difference between the Compton scattering angle and the geometric angle, random events can be rejected.

  6. Compton suppression spectrometry for analysis of short-lived neutron activation products in foods

    International Nuclear Information System (INIS)

    Anderson, D.L.; Cunningham, W.C.

    2008-01-01

    Compton suppression spectrometry was used to analyze foods for elements with short-lived neutron activation products (half-lives of about 2 minutes to 1.5 days). Analysis conditions were optimized to provide quality assurance analyses for iodine in FDA's Total Diet Study. Iodine mass fractions (0.075 to 2.03 mg/kg) were measured in 19 of 42 foods analyzed, with limits of detection (LODs) ranging from 0.03 to 1.4 mg/kg, mostly depending on NaCl content. LODs were lowered by up to a factor of 2 for 16 elements. Suppression factors ranged from about 2 to 8 over the energy range 400 to 3200 keV. (author)

  7. Induced Compton scattering effects in radiation transport approximations

    International Nuclear Information System (INIS)

    Gibson, D.R. Jr.

    1982-01-01

    In this thesis 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

  8. Quantitative Compton suppression spectrometry at elevated counting rates

    International Nuclear Information System (INIS)

    Westphal, G.P.; Joestl, K.; Schroeder, P.; Lauster, R.; Hausch, E.

    1999-01-01

    For quantitative Compton suppression spectrometry the decrease of coincidence efficiency with counting rate should be made negligible to avoid a virtual increase of relative peak areas of coincident isomeric transitions with counting rate. To that aim, a separate amplifier and discriminator has been used for each of the eight segments of the active shield of a new well-type Compton suppression spectrometer, together with an optimized, minimum dead-time design of the anticoincidence logic circuitry. Chance coincidence losses in the Compton suppression spectrometer are corrected instrumentally by comparing the chance coincidence rate to the counting rate of the germanium detector in a pulse-counting Busy circuit (G.P. Westphal, J. Rad. Chem. 179 (1994) 55) which is combined with the spectrometer's LFC counting loss correction system. The normally not observable chance coincidence rate is reconstructed from the rates of germanium detector and scintillation detector in an auxiliary coincidence unit, after the destruction of true coincidence by delaying one of the coincidence partners. Quantitative system response has been tested in two-source measurements with a fixed reference source of 60 Co of 14 kc/s, and various samples of 137 Cs, up to aggregate counting rates of 180 kc/s for the well-type detector, and more than 1400 kc/s for the BGO shield. In these measurements, the net peak areas of the 1173.3 keV line of 60 Co remained constant at typical values of 37 000 with and 95 000 without Compton suppression, with maximum deviations from the average of less than 1.5%

  9. Compton scattering collision module for OSIRIS

    Science.gov (United States)

    Del Gaudio, Fabrizio; Grismayer, Thomas; Fonseca, Ricardo; Silva, Luís

    2017-10-01

    Compton scattering plays a fundamental role in a variety of different astrophysical environments, such as at the gaps of pulsars and the stagnation surface of black holes. In these scenarios, Compton scattering is coupled with self-consistent mechanisms such as pair cascades. We present the implementation of a novel module, embedded in the self-consistent framework of the PIC code OSIRIS 4.0, capable of simulating Compton scattering from first principles and that is fully integrated with the self-consistent plasma dynamics. The algorithm accounts for the stochastic nature of Compton scattering reproducing without approximations the exchange of energy between photons and unbound charged species. We present benchmarks of the code against the analytical results of Blumenthal et al. and the numerical solution of the linear Kompaneets equation and good agreement is found between the simulations and the theoretical models. This work is supported by the European Research Council Grant (ERC- 2015-AdG 695088) and the Fundao para a Céncia e Tecnologia (Bolsa de Investigao PD/BD/114323/2016).

  10. High-pressure system for Compton scattering experiments

    International Nuclear Information System (INIS)

    Oomi, G.; Honda, F.; Kagayama, T.; Itoh, F.; Sakurai, H.; Kawata, H.; Shimomura, O.

    1998-01-01

    High-pressure apparatus for Compton scattering experiments has been developed to study the momentum distribution of conduction electrons in metals and alloys at high pressure. This apparatus was applied to observe the Compton profile of metallic Li under pressure. It was found that the Compton profile at high pressure could be obtained within several hours by using this apparatus and synchrotron radiation. The result on the pressure dependence of the Fermi momentum of Li obtained here is in good agreement with that predicted from the free-electron model

  11. Weak Deeply Virtual Compton Scattering

    International Nuclear Information System (INIS)

    Ales Psaker; Wolodymyr Melnitchouk; Anatoly Radyushkin

    2006-01-01

    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

  12. Development of a Compton camera for online ion beam range verification via prompt γ detection

    Energy Technology Data Exchange (ETDEWEB)

    Aldawood, S. [LMU Munich, Garching (Germany); King Saud University, Riyadh (Saudi Arabia); Liprandi, S.; Marinsek, T.; Bortfeldt, J.; Lang, C.; Lutter, R.; Dedes, G.; Parodi, K.; Thirolf, P.G. [LMU Munich, Garching (Germany); Maier, L.; Gernhaeuser, R. [TU Munich, Garching (Germany); Kolff, H. van der [LMU Munich, Garching (Germany); TU Delft (Netherlands); Castelhano, I. [LMU Munich, Garching (Germany); University of Lisbon, Lisbon (Portugal); Schaart, D.R. [TU Delft (Netherlands)

    2015-07-01

    Precise and preferably online ion beam range verification is a mandatory prerequisite to fully exploit the advantages of hadron therapy in cancer treatment. An imaging system is being developed in Garching aiming to detect promptγ rays induced by nuclear reactions between the ion beam and biological tissue. The Compton camera prototype consists of a stack of six customized double-sided Si-strip detectors (DSSSD, 50 x 50 mm{sup 2}, 0.5 mm thick, 128 strips/side) acting as scatterer, while the absorber is formed by a monolithic LaBr{sub 3}:Ce scintillator crystal (50 x 50 x 30 mm{sup 3}) read out by a position-sensitive multi-anode photomultiplier (Hamamatsu H9500). The on going characterization of the Compton camera properties and its individual components both offline in the laboratory as well as online using proton beam are presented.

  13. Compton suppression through rise-time analysis

    International Nuclear Information System (INIS)

    Selvi, S.; Celiktas, C.

    2007-01-01

    We studied Compton suppression for 60 Co and 137 Cs radioisotopes using a signal selection criterion based on contrasting the fall time of the signals composing the photo peak with those composing the Compton continuum. The fall time criterion is employed by using the pulse shape analysis observing the change in the fall times of the gamma-ray pulses. This change is determined by measuring the changes in the rise times related to the fall time of the scintillator and the timing signals related to the fall time of the input signals. We showed that Compton continuum suppression is achieved best via the precise timing adjustment of an analog rise-time analyzer connected to a NaI(Tl) scintillation spectrometer

  14. A New Compton-Thick AGN in Our Cosmic Backyard: Unveiling the Buried Nucleus in NGC 1448 with NuSTAR

    Science.gov (United States)

    Annuar, A.; Alexander, D. M.; Ghandi, P.; Lansbury, G. B.; Asmus, D.; Ballantyne, D. R.; Bauer, F. E.; Boggs, S. E.; Boorman, P. G.; Brandt, W. N.; hide

    2017-01-01

    NGC 1448 is one of the nearest luminous galaxies [L(sub 8) - 1000 micrometers is greater than 10(exp. 9) Solar Luminosity] to ours (z = 0.00390), and yet the active galactic nucleus (AGN) it hosts was only recently discovered, in 2009. In this paper, we present an analysis of the nuclear source across three wavebands: mid-infrared (MIR) continuum, optical, and X-rays. We observed the source with the Nuclear Spectroscopic Telescope Array (NuSTAR), and combined these data with archival Chandra data to perform broadband X-ray spectral fitting ( approx. equals 0.5 - 40 keV) of the AGN for the first time. Our X-ray spectral analysis reveals that the AGN is buried under a Compton-thick (CT) column of obscuring gas along our line of sight, with a column density of N(sub H)(los) approx. greater than 2.5 x 10(exp. 24) cm(exp. -2). The best-fitting torus models measured an intrinsic 2-10 keV luminosity of L(sub 2)-10,int = (3.5 - 7.6) x 10(exp. 40) erg s(exp. -1), making NGC 1448 one of the lowest luminosity CTAGNs known. In addition to the NuSTAR observation, we also performed optical spectroscopy for the nucleus in this edge-on galaxy using the European Southern Observatory New Technology Telescope. We reclassify the optical nuclear spectrum as a Seyfert on the basis of the Baldwin- Philips-Terlevich diagnostic diagrams, thus identifying the AGN at optical wavelengths for the first time. We also present high spatial resolution MIR observations of NGC 1448 with Gemini/T-ReCS, in which a compact nucleus is clearly detected. The absorption-corrected 2-10 keV luminosity measured from our X-ray spectral analysis agrees with that predicted from the optical [O III] Lamda 5007 A emission line and the MIR 12 micrometer continuum, further supporting the CT nature ofthe AGN.

  15. The effect of Compton scattering on quantitative SPECT imaging

    International Nuclear Information System (INIS)

    Beck, J.W.; Jaszczak, R.J.; Starmer, C.F.

    1982-01-01

    A Monte Carlo code has been developed to simulate the response of a SPECT system. The accuracy of the code has been verified and has been used in this research to study and illustrate the effects of Compton scatter on quantitative SPECT measurements. The effects of Compton scattered radiation on gamma camera response have been discussed by several authors, and will be extended to rotating gamma camera SPECT systems. The unique feature of this research includes the pictorial illustration of the Compton scattered and the unscattered components of the photopeak data on SPECT imaging by simulating phantom studies with and without Compton scatter

  16. Testing special relativity theory using Compton scattering

    International Nuclear Information System (INIS)

    Contreras S, H.; Hernandez A, L.; Baltazar R, A.; Escareno J, E.; Mares E, C. A.; Hernandez V, C.; Vega C, H. R.

    2010-10-01

    The validity of the special relativity theory has been tested using the Compton scattering. Since 1905 several experiments has been carried out to show that time, mass, and length change with the velocity, in this work the Compton scattering has been utilized as a simple way to show the validity to relativity. The work was carried out through Monte Carlo calculations and experiments with different gamma-ray sources and a gamma-ray spectrometer with a 3 x 3 NaI (Tl) detector. The pulse-height spectra were collected and the Compton edge was observed. This information was utilized to determine the relationship between the electron's mass and energy using the Compton -knee- position, the obtained results were contrasted with two collision models between photon and electron, one model was built using the classical physics and another using the special relativity theory. It was found that calculations and experiments results fit to collision model made using the special relativity. (Author)

  17. Discovery of a Kiloparsec Extended Hard X-Ray Continuum and Fe-Kα from the Compton Thick AGN ESO 428-G014

    Science.gov (United States)

    Fabbiano, G.; Elvis, M.; Paggi, A.; Karovska, M.; Maksym, W. P.; Raymond, J.; Risaliti, G.; Wang, Junfeng

    2017-06-01

    We report the discovery of kiloparsec-scale diffuse emission in both the hard continuum (3-6 keV) and in the Fe-Kα line in the Compton thick (CT) Seyfert galaxy ESO 428-G014. This extended hard component contains at least ˜24% of the observed 3-8 keV emission, and follows the direction of the extended optical line emission (ionization cone) and radio jet. The extended hard component has ˜0.5% of the intrinsic 2-10 keV luminosity within the bi-cones. A uniform scattering medium of density 1 {{cm}}-3 would produce this luminosity in a 1 kpc path length in the bi-cones. Alternatively, higher column density molecular clouds in the disk of ESO 428-G014 may be responsible for these components. The continuum may also be enhanced by the acceleration of charged particles in the radio jet. The steeper spectrum (Γ ˜ 1.7 ± 0.4) of the hard continuum outside of the central 1.″5 radius nuclear region suggests a contribution of scattered/fluorescent intrinsic Seyfert emission. Ultrafast nuclear outflows cannot explain the extended Fe-Kα emission. This discovery suggests that we may need to revise the picture at the base of our interpretation of CT AGN spectra.

  18. Crystal Compton Camera

    Energy Technology Data Exchange (ETDEWEB)

    Ziock, Klaus-Peter [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Braverman, Joshua B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Harrison, Mark J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Hornback, Donald Eric [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Fabris, Lorenzo [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Newby, Jason [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2013-09-26

    Stand-off detection is one of the most important radiation detection capabilities for arms control and the control of illicit nuclear materials. For long range passive detection one requires a large detector and a means of “seeing through” the naturally occurring and varying background radiation, i.e. imaging. Arguably, Compton imaging is the best approach over much of the emission band suitable for long range detection. It provides not only imaging, but more information about the direction of incidence of each detected gamma-ray than the alternate approach of coded-aperture imaging. The directional information allows one to reduce the background and hence improve the sensitivity of a measurement. However, to make an efficient Compton imager requires localizing and measuring the simultaneous energy depositions when gamma-rays Compton scatter and are subsequently captured within a single, large detector volume. This concept has been demonstrated in semi-conductor detectors (HPGe, CZT, Si) but at ~ $1k/cm3 these materials are too expensive to build the large systems needed for standoff detection. Scintillator detectors, such as NaI(Tl), are two orders of magnitude less expensive and possess the energy resolution required to make such an imager. However, they do not currently have the ability to localize closely spaced, simultaneous energy depositions in a single large crystal. In this project we are applying a new technique that should, for the first time ever, allow cubic-millimeter event localization in a bulk scintillator crystal.

  19. Compton suppression naa in the analysis of food and beverages

    International Nuclear Information System (INIS)

    Ahmed, Y.A.; Ewa, I.O.B.; Umar, I.M.; Funtua, I.I.; Lanberger, S.; O'kelly, D.J.; Braisted, J.D.

    2009-01-01

    Applicability and performance of Compton suppression method in the analysis of food and beverages was re-established in this study. Using ''1''3''7Cs and ''6''0Co point sources Compton Suppression Factors (SF), Compton Reduction Factors (RF), Peak-to-Compton ratio (P/C), Compton Plateau (C p l), and Compton Edge (C e ) were determined for each of the two sources. The natural background reduction factors in the anticoincidence mode compared to the normal mode were evaluated. The reported R.F. values of the various Compton spectrometers for ''6''0Co source at energy 50-210 keV (backscattering region), 600 keV (Compton edge corresponding to 1173.2 keV gamma-ray) and 1110 keV (Compton edge corresponding to 1332.5 keV gamma-ray) were compared with that of the present work. Similarly the S.F. values of the spectrometers for ''1''3''7Cs source were compared at the backscattered energy region (S.F. b = 191-210 keV), Compton Plateau (S.F. p l = 350-370 keV), and Compton Edge (S.F. e = 471-470 keV) and all were found to follow a similar trend. We also compared peak reduction ratios for the two cobalt energies (1173.2 and 1332.5) with the ones reported in literature and two results agree well. Applicability of the method to food and beverages was put to test for twenty one major, minor, and trace elements (Ba, Sr, I, Br, Cu, V, Mg, Na, Cl, Mn, Ca, Sn,K, Cd, Zn, As, Sb, Ni, Cs, Fe, and Co) commonly found in food, milk, tea and tobacco. The elements were assayed using five National Institute for Standards and Technology (NIST) certified reference materials (Non-fat powdered milk, Apple leaves, Tomato leaves, and Citrus leaves). The results obtained shows good agreement with NIST certified values, indicating that the method is suitable for simultaneous determination of micro-nutrients, macro-nutrients and heavy elements in food and beverages without undue interference problems

  20. HEROIC: 3D general relativistic radiative post-processor with comptonization for black hole accretion discs

    Science.gov (United States)

    Narayan, Ramesh; Zhu, Yucong; Psaltis, Dimitrios; Saḑowski, Aleksander

    2016-03-01

    We describe Hybrid Evaluator for Radiative Objects Including Comptonization (HEROIC), an upgraded version of the relativistic radiative post-processor code HERO described in a previous paper, but which now Includes Comptonization. HEROIC models Comptonization via the Kompaneets equation, using a quadratic approximation for the source function in a short characteristics radiation solver. It employs a simple form of accelerated lambda iteration to handle regions of high scattering opacity. In addition to solving for the radiation field, HEROIC also solves for the gas temperature by applying the condition of radiative equilibrium. We present benchmarks and tests of the Comptonization module in HEROIC with simple 1D and 3D scattering problems. We also test the ability of the code to handle various relativistic effects using model atmospheres and accretion flows in a black hole space-time. We present two applications of HEROIC to general relativistic magnetohydrodynamics simulations of accretion discs. One application is to a thin accretion disc around a black hole. We find that the gas below the photosphere in the multidimensional HEROIC solution is nearly isothermal, quite different from previous solutions based on 1D plane parallel atmospheres. The second application is to a geometrically thick radiation-dominated accretion disc accreting at 11 times the Eddington rate. Here, the multidimensional HEROIC solution shows that, for observers who are on axis and look down the polar funnel, the isotropic equivalent luminosity could be more than 10 times the Eddington limit, even though the spectrum might still look thermal and show no signs of relativistic beaming.

  1. Compton suppression instrumental neutron activation analysis performance in determining trace- and minor-element contents in foodstuff

    International Nuclear Information System (INIS)

    Freitas, M.C.; Dionisio, I.; Pacheco, A.M.G.; Bacchi, M.A.; Fernandes, E.A.N.; Landsberger, S.; Braisted, J.

    2008-01-01

    In 2003-2004, several food items were purchased from large commercial outlets in Coimbra, Portugal. Such items included meats (chicken, pork, beef), eggs, rice, beans and vegetables (tomato, carrot, potato, cabbage, broccoli, lettuce). Elemental analysis was carried out through INAA at the Technological and Nuclear Institute (ITN, Portugal), the Nuclear Energy Centre for Agriculture (CENA, Brazil), and the Nuclear Engineering Teaching Lab of the University of Texas at Austin (NETL, USA). At the latter two, INAA was also associated to Compton suppression. It can be concluded that by applying Compton suppression (1) the detection limits for arsenic, copper and potassium improved; (2) the counting-statistics error for molybdenum diminished; and (3) the long-lived zinc had its 1115-keV photopeak better defined. In general, the improvement sought by introducing Compton suppression in foodstuff analysis was not significant. Lettuce, cabbage and chicken (liver, stomach, heart) are the richest diets in terms of human nutrients. (author)

  2. Development of a Compton suppression whole body counting for small animals; Desenvolvimento de um detetor de corpo inteiro com supressao Compton para pequenos animais

    Energy Technology Data Exchange (ETDEWEB)

    Martini, Elaine

    1996-12-31

    The basic operation, design and construction of the plastic scintillator detector is described. In order to increase the sensitivity of this detector, two blocks of plastic scintillator have been assembled to act as a anticompton system. The detectors were produced by polymerisation of styrene monomer with PPO (2,5 diphenyl-oxazole) and POPOP (1,4 bis (-5 phenyl-2- oxazoly)benzene) in proportions of 0.5 and 0.05 respectively. The transparency of this detector was evaluated by excitation of the {sup 241} Am source located directly in the back surface plastic coupled to a photomultiplier. The light attenuation according to the detector thickness has fitted to a two-exponential function: relative height pulse = 0,519 e{sup -0.0016} + 0.481 e{sup -0.02112.x}. Four radioactive sources{sup {sup 2}2} Na, {sup 54} Mn, {sup 137} Cs and {sup 131} I were used to evaluate the performance of this system. The Compton reduction factor, determined by the ratio of the energy peak values of suppressed and unsuppressed spectra was 1.16. The Compton suppression factor determined by the ratio of the net photopeak area to the area of an equal spectra width in the Compton continuum, was approximately 1.208 {+-} 0.109. The sensitivity of the system, defined as the least amount of a radioactivity that can be quantified in the photopeak region, was 9.44 cps. First, the detector was assembled to be applied in biological studies of whole body counter measurements of small animals. Using a phantom, (small animal simulator) and a punctual {sup 137} Cs source, located in the central region of the well counter the geometrical efficiency detector was about 5%. (author) 40 refs., 28 fifs., 2 tabs.

  3. Development of a Compton suppression whole body counting for small animals; Desenvolvimento de um detetor de corpo inteiro com supressao Compton para pequenos animais

    Energy Technology Data Exchange (ETDEWEB)

    Martini, Elaine

    1995-12-31

    The basic operation, design and construction of the plastic scintillator detector is described. In order to increase the sensitivity of this detector, two blocks of plastic scintillator have been assembled to act as a anticompton system. The detectors were produced by polymerisation of styrene monomer with PPO (2,5 diphenyl-oxazole) and POPOP (1,4 bis (-5 phenyl-2- oxazoly)benzene) in proportions of 0.5 and 0.05 respectively. The transparency of this detector was evaluated by excitation of the {sup 241} Am source located directly in the back surface plastic coupled to a photomultiplier. The light attenuation according to the detector thickness has fitted to a two-exponential function: relative height pulse = 0,519 e{sup -0.0016} + 0.481 e{sup -0.02112.x}. Four radioactive sources{sup {sup 2}2} Na, {sup 54} Mn, {sup 137} Cs and {sup 131} I were used to evaluate the performance of this system. The Compton reduction factor, determined by the ratio of the energy peak values of suppressed and unsuppressed spectra was 1.16. The Compton suppression factor determined by the ratio of the net photopeak area to the area of an equal spectra width in the Compton continuum, was approximately 1.208 {+-} 0.109. The sensitivity of the system, defined as the least amount of a radioactivity that can be quantified in the photopeak region, was 9.44 cps. First, the detector was assembled to be applied in biological studies of whole body counter measurements of small animals. Using a phantom, (small animal simulator) and a punctual {sup 137} Cs source, located in the central region of the well counter the geometrical efficiency detector was about 5%. (author) 40 refs., 28 fifs., 2 tabs.

  4. An experimental method for the optimization of anti-Compton spectrometer

    CERN Document Server

    Badran, H M

    1999-01-01

    The reduction of the Compton continuum can be achieved using a Compton suppression shield. For the first time, an experimental method is purposed for estimating the optimum dimensions of such a shield. The method can also provide information on the effect of the air gap, source geometry, gamma-ray energy, etc., on the optimum dimension of the active shield. The method employs the measurements of the Compton suppression efficiency in two dimensions using small size scintillation detectors. Two types of scintillation materials; NaI(Tl) and NE-102A plastic scintillators, were examined. The effect of gamma-ray energy and source geometry were also investigated using sup 1 sup 3 sup 7 Cs and sup 6 sup 0 Co sources with three geometries; point, cylindrical, and Marinelli shapes. The results indicate the importance of both NaI(Tl) and NE-102A guard detectors in surrounding the main detector rather than the distance above it. The ratio between the part of the guard detector above the surface of the main detector to th...

  5. Doppler broadening and its contribution to Compton energy-absorption cross sections: An analysis of the Compton component in terms of mass-energy absorption coefficient

    International Nuclear Information System (INIS)

    Rao, D.V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G.E.

    2002-01-01

    Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1 deg. -180 deg. . Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1 deg. -180 deg., for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance

  6. Doppler Broadening and its Contribution to Compton Energy-Absorption Cross Sections: An Analysis of the Compton Component in Terms of Mass-Energy Absorption Coefficient

    Science.gov (United States)

    Rao, D. V.; Takeda, T.; Itai, Y.; Akatsuka, T.; Cesareo, R.; Brunetti, A.; Gigante, G. E.

    2002-09-01

    Compton energy absorption cross sections are calculated using the formulas based on a relativistic impulse approximation to assess the contribution of Doppler broadening and to examine the Compton profile literature and explore what, if any, effect our knowledge of this line broadening has on the Compton component in terms of mass-energy absorption coefficient. Compton energy-absorption cross sections are evaluated for all elements, Z=1-100, and for photon energies 1 keV-100 MeV. Using these cross sections, the Compton component of the mass-energy absorption coefficient is derived in the energy region from 1 keV to 1 MeV for all the elements Z=1-100. The electron momentum prior to the scattering event should cause a Doppler broadening of the Compton line. The momentum resolution function is evaluated in terms of incident and scattered photon energy and scattering angle. The overall momentum resolution of each contribution is estimated for x-ray and γ-ray energies of experimental interest in the angular region 1°-180°. Also estimated is the Compton broadening using nonrelativistic formula in the angular region 1°-180°, for 17.44, 22.1, 58.83, and 60 keV photons for a few elements (H, C, N, O, P, S, K, and Ca) of biological importance.

  7. Development of a Compton suppression whole body counting for small animals

    International Nuclear Information System (INIS)

    Martini, Elaine

    1995-01-01

    The basic operation, design and construction of the plastic scintillator detector is described. In order to increase the sensitivity of this detector, two blocks of plastic scintillator have been assembled to act as a anticompton system. The detectors were produced by polymerisation of styrene monomer with PPO (2,5 diphenyl-oxazole) and POPOP (1,4 bis (-5 phenyl-2- oxazoly)benzene) in proportions of 0.5 and 0.05 respectively. The transparency of this detector was evaluated by excitation of the 241 Am source located directly in the back surface plastic coupled to a photomultiplier. The light attenuation according to the detector thickness has fitted to a two-exponential function: relative height pulse = 0,519 e -0.0016 + 0.481 e -0.02112.x . Four radioactive sources 2 2 Na, 54 Mn, 137 Cs and 131 I were used to evaluate the performance of this system. The Compton reduction factor, determined by the ratio of the energy peak values of suppressed and unsuppressed spectra was 1.16. The Compton suppression factor determined by the ratio of the net photopeak area to the area of an equal spectra width in the Compton continuum, was approximately 1.208 ± 0.109. The sensitivity of the system, defined as the least amount of a radioactivity that can be quantified in the photopeak region, was 9.44 cps. First, the detector was assembled to be applied in biological studies of whole body counter measurements of small animals. Using a phantom, (small animal simulator) and a punctual 137 Cs source, located in the central region of the well counter the geometrical efficiency detector was about 5%. (author)

  8. Compton spectra of atoms at high x-ray intensity

    Science.gov (United States)

    Son, Sang-Kil; Geffert, Otfried; Santra, Robin

    2017-03-01

    Compton scattering is the nonresonant inelastic scattering of an x-ray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high x-ray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom. As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL-matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible. , which features invited work from the best early-career researchers working within the scope of J. Phys. B. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Sang-Kil Son was selected by the Editorial Board of J. Phys. B as an Emerging Leader.

  9. Compton suppression system at Penn State Radiation Science and Engineering Center

    International Nuclear Information System (INIS)

    Cetiner, N.Oe.; Uenlue, K.; Brenizer, J.S.

    2008-01-01

    A Compton suppression system is used to reduce the contribution of scattered gamma-rays that originate within the HPGe detector to the gamma ray spectrum. The HPGe detector is surrounded by an assembly of guard detectors, usually NaI(Tl). The HPGe and NaI(Tl) detectors are operated in anti-coincidence mode. The NaI(Tl) guard detector detects the photons that Compton scatter within, and subsequently escape from the HPGe detector. Since these photons are correlated with the partial energy deposition within the detector, much of the resulting Compton continuum can be subtracted from the spectrum reducing the unwanted background in gamma-ray spectra. A commercially available Compton suppression spectrometer (CSS) was purchased from Canberra Industries and tested at the Radiation Science and Engineering Center at Penn State University. The PSU-CSS includes a reverse bias HPGe detector, four annulus NaI(Tl) detectors, a NaI(Tl) plug detector, detector shields, data acquisition electronics, and a data processing computer. The HPGe detector is n-type with 54% relative efficiency. The guard detectors form an annulus with 9-inch diameter and 9-inch height, and have a plug detector that goes into/out of the annulus with the help of a special lift apparatus to raise/lower. The detector assembly is placed in a shielding cave. State-of-the-art electronics and software are used. The system was tested using standard sources, neutron activated NIST SRM sample and Dendrochronologically Dated Tree Ring samples. The PSU-CSS dramatically improved the peak-to-Compton ratio, up to 1000 : 1 for the 137 Cs source. (author)

  10. A new gamma-ray diagnostic for energetic ion distributions - The Compton tail on the neutron capture line

    International Nuclear Information System (INIS)

    Vestrand, W.T.

    1990-01-01

    This paper presents a new radiation diagnostic for assaying the energy spectrum and the angular distribution of energetic ions incident on thick hydrogen-rich thermal targets. This diagnostic compares the number of emergent photons in the narrow neutron capture line at 2.223 MeV to the number of Compton scattered photons that form a low-energy tail on the line. It is shown that the relative strength of the tail can be used as a measure of the hardness of the incident ion-energy spectrum. Application of this diagnostic to solar flare conditions is the main thrust of the work presented here. It is examined how the strength of the Compton tail varies with flare viewing angle and the angular distribution of the flare-accelerated particles. Application to compact X-ray binary systems is also briefly discussed. 39 refs

  11. A filtered backprojection reconstruction algorithm for Compton camera

    Energy Technology Data Exchange (ETDEWEB)

    Lojacono, Xavier; Maxim, Voichita; Peyrin, Francoise; Prost, Remy [Lyon Univ., Villeurbanne (France). CNRS, Inserm, INSA-Lyon, CREATIS, UMR5220; Zoglauer, Andreas [California Univ., Berkeley, CA (United States). Space Sciences Lab.

    2011-07-01

    In this paper we present a filtered backprojection reconstruction algorithm for Compton Camera detectors of particles. Compared to iterative methods, widely used for the reconstruction of images from Compton camera data, analytical methods are fast, easy to implement and avoid convergence issues. The method we propose is exact for an idealized Compton camera composed of two parallel plates of infinite dimension. We show that it copes well with low number of detected photons simulated from a realistic device. Images reconstructed from both synthetic data and realistic ones obtained with Monte Carlo simulations demonstrate the efficiency of the algorithm. (orig.)

  12. Compton scatter imaging: A tool for historical exploration

    International Nuclear Information System (INIS)

    Harding, G.; Harding, E.

    2010-01-01

    This review discusses the principles and technological realisation of a technique, termed Compton scatter imaging (CSI), which is based on spatially resolved detection of Compton scattered X-rays. The applicational focus of this review is to objects of historical interest. Following a historical survey of CSI, a description is given of the major characteristics of Compton X-ray scatter. In particular back-scattered X-rays allow massive objects to be imaged, which would otherwise be too absorbing for the conventional transmission X-ray technique. The ComScan (an acronym for Compton scatter scanner) is a commercially available backscatter imaging system, which is discussed here in some detail. ComScan images from some artefacts of historical interest, namely a fresco, an Egyptian mummy and a mediaeval clasp are presented and their use in historical analysis is indicated. The utility of scientific and technical advance for not only exploring history, but also restoring it, is briefly discussed.

  13. Halogen determination in Arctic aerosols by neutron activation analysis with Compton suppression methods

    International Nuclear Information System (INIS)

    Landsberger, S.; Basunia, M.S.; Iskander, F.

    2001-01-01

    The study of halogens particularly bromine and chlorine in Arctic aerosols has received a great deal of attention in the past decade in ozone depletion during polar sunrise studies. Iodine has also been studied as part of geochemical cycling. It was shown that all three of the above elements can be determined simultaneously with very low detection limits using epithermal NAA in conjunction with Compton suppression methods. Besides lowering the background considerably, Compton suppression can eliminate or minimize the overlapping peak of the 620 keV photopeak arising form the 1642 keV double escape peak of 38 Cl interfering with the 616.9 keV photopeak of 79 Br(n,γ) 80 Br reaction. Iodine is ideally determined by epithermal NAA because of its very good resonance integral cross-section. Although chlorine is usually determined using thermal neutrons via the 37 Cl(n,γ) 38 Cl reactions, epithermal NAA is still feasible for the Arctic aerosol, since it has a major sea-salt component. (author)

  14. Deconvolution of shift-variant broadening for Compton scatter imaging

    International Nuclear Information System (INIS)

    Evans, Brian L.; Martin, Jeffrey B.; Roggemann, Michael C.

    1999-01-01

    A technique is presented for deconvolving shift-variant Doppler broadening of singly Compton scattered gamma rays from their recorded energy distribution. Doppler broadening is important in Compton scatter imaging techniques employing gamma rays with energies below roughly 100 keV. The deconvolution unfolds an approximation to the angular distribution of scattered photons from their recorded energy distribution in the presence of statistical noise and background counts. Two unfolding methods are presented, one based on a least-squares algorithm and one based on a maximum likelihood algorithm. Angular distributions unfolded from measurements made on small scattering targets show less evidence of Compton broadening. This deconvolution is shown to improve the quality of filtered backprojection images in multiplexed Compton scatter tomography. Improved sharpness and contrast are evident in the images constructed from unfolded signals

  15. Development of Compton X-ray spectrometer for high energy resolution single-shot high-flux hard X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, Sadaoki, E-mail: kojima-s@ile.osaka-u.ac.jp, E-mail: sfujioka@ile.osaka-u.ac.jp; Ikenouchi, Takahito; Arikawa, Yasunobu; Sakata, Shohei; Zhang, Zhe; Abe, Yuki; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke, E-mail: kojima-s@ile.osaka-u.ac.jp, E-mail: sfujioka@ile.osaka-u.ac.jp; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Ozaki, Tetsuo [National Institute for Fusion Science, 322-6 Oroshi, Toki, Gifu 509-5292 (Japan); Miyamoto, Shuji; Yamaguchi, Masashi; Takemoto, Akinori [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori-cho, Ako-gun, Hyogo 678-1205 (Japan)

    2016-04-15

    Hard X-ray spectroscopy is an essential diagnostics used to understand physical processes that take place in high energy density plasmas produced by intense laser-plasma interactions. A bundle of hard X-ray detectors, of which the responses have different energy thresholds, is used as a conventional single-shot spectrometer for high-flux (>10{sup 13} photons/shot) hard X-rays. However, high energy resolution (Δhv/hv < 0.1) is not achievable with a differential energy threshold (DET) X-ray spectrometer because its energy resolution is limited by energy differences between the response thresholds. Experimental demonstration of a Compton X-ray spectrometer has already been performed for obtaining higher energy resolution than that of DET spectrometers. In this paper, we describe design details of the Compton X-ray spectrometer, especially dependence of energy resolution and absolute response on photon-electron converter design and its background reduction scheme, and also its application to the laser-plasma interaction experiment. The developed spectrometer was used for spectroscopy of bremsstrahlung X-rays generated by intense laser-plasma interactions using a 200 μm thickness SiO{sub 2} converter. The X-ray spectrum obtained with the Compton X-ray spectrometer is consistent with that obtained with a DET X-ray spectrometer, furthermore higher certainly of a spectral intensity is obtained with the Compton X-ray spectrometer than that with the DET X-ray spectrometer in the photon energy range above 5 MeV.

  16. Laser Compton polarimetry at JLab and MAMI. A status report

    International Nuclear Information System (INIS)

    Diefenbach, J.; Imai, Y.; Han Lee, J.; Maas, F.; Taylor, S.

    2007-01-01

    For modern parity violation experiments it is crucial to measure and monitor the electron beam polarization continuously. In the recent years different high-luminosity concepts, for precision Compton backscattering polarimetry, have been developed, to be used at modern CW electron beam accelerator facilities. As Compton backscattering polarimetry is free of intrinsic systematic uncertainties, it can be a superior alternative to other polarimetry techniques such as Moeller and Mott scattering. State-of-the-art high-luminosity Compton backscattering designs currently in use and under development at JLab and Mainz are compared to each other. The latest results from the Mainz A4 Compton polarimeter are presented. (orig.)

  17. Virtual compton scattering off protons at moderately large momentum transfer

    International Nuclear Information System (INIS)

    Kroll, P.; Schuermann, M.; Guichon, P.A.M.

    1995-01-01

    The amplitudes for virtual Compton scattering off protons are calculated within the framework of the diquark model in which protons are viewed as being built up by quarks and diquarks. The latter objects are treated as quasi-elementary constituents of the proton. Virtual Compton scattering, electroproduction of photons and the Bethe-Heitler contamination are discussed for various kinematical situations. We particularly emphasize the role of the electron asymmetry for measuring the relative phases between the virtual Compton and the Bethe-Heitler amplitudes. It is also shown that the model is able to describe very well the experimental data for real Compton scattering off protons. (authors). 35 refs., 8 figs., 1 tab

  18. Virtual compton scattering off protons at moderately large momentum transfer

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, P; Schuermann, M [Wuppertal Univ. (Gesamthochschule) (Germany); Guichon, P A.M. [CEA Centre d` Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d` Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l` Instrumentation Associee

    1995-06-28

    The amplitudes for virtual Compton scattering off protons are calculated within the framework of the diquark model in which protons are viewed as being built up by quarks and diquarks. The latter objects are treated as quasi-elementary constituents of the proton. Virtual Compton scattering, electroproduction of photons and the Bethe-Heitler contamination are discussed for various kinematical situations. We particularly emphasize the role of the electron asymmetry for measuring the relative phases between the virtual Compton and the Bethe-Heitler amplitudes. It is also shown that the model is able to describe very well the experimental data for real Compton scattering off protons. (authors). 35 refs., 8 figs., 1 tab.

  19. Virtual Compton scattering off protons at moderately large momentum transfer

    International Nuclear Information System (INIS)

    Kroll, P.

    1996-01-01

    The amplitudes for virtual Compton scattering off protons are calculated within the framework of the diquark model in which protons are viewed as being built up by quarks and diquarks. The latter objects are treated as quasi-elementary constituents of the proton. Virtual Compton scattering, electroproduction off protons and the Bethe-Heitler contamination are photon discussed for various kinematical situations. We particularly emphasize the role of the electron asymmetry for measuring the relative phases between the virtual Compton and the Bethe-Heitler amplitudes. It is also shown that the model is able to describe very well the experimental data for real Compton scattering off protons. (orig.)

  20. Design of A HPGe-Plastic Scintillator Compton Suppression Spectrometer for Neutron Activation Analysis and Radio environmental Studies

    International Nuclear Information System (INIS)

    Sharshar, T.; Badran, H.; Elnimr, T.

    1998-01-01

    The design of a compton suppression spectrometer consisting of a 10% p-type HPGe detector and an annular anti-Compton shield made of N E-102 A plastic scintillator is described. The height of the guard plastic- scintillation detector was optimized experimentally using a NaI(Ti) ring, consisting of five NaI(Ti) detectors. The annular guard detector is divided to four optically isolated quarters to enhance the light collection. Each quarter of the guard detector was tested and satisfying results are obtained

  1. XMM FOLLOW-UP OBSERVATIONS OF THREE SWIFT BAT-SELECTED ACTIVE GALACTIC NUCLEI

    International Nuclear Information System (INIS)

    Trippe, M. L.; Reynolds, C. S.; Koss, M.; Mushotzky, R. F.; Winter, L. M.

    2011-01-01

    We present XMM-Newton observations of three active galactic nuclei (AGNs) taken as part of a hunt to find very heavily obscured Compton-thick AGNs. For obscuring columns greater than 10 25 cm -2 , AGNs are only visible at energies below 10 keV via reflected/scattered radiation, characterized by a flat power law. We therefore selected three objects (ESO 417-G006, IRAS 05218-1212, and MCG -01-05-047) from the Swift Burst Alert Telescope (BAT) hard X-ray survey catalog with Swift X-ray Telescope (XRT) 0.5-10 keV spectra with flat power-law indices as candidate Compton-thick sources for follow-up observations with the more sensitive instruments on XMM-Newton. The XMM spectra, however, rule out reflection-dominated models based on the weakness of the observed Fe Kα lines. Instead, the spectra are well fit by a model of a power-law continuum obscured by a Compton-thin absorber plus a soft excess. This result is consistent with previous follow-up observations of two other flat-spectrum BAT-detected AGNs. Thus, out of the six AGNs in the 22 month BAT catalog with apparently flat Swift XRT spectra, all five that have had follow-up observations are not likely Compton thick. We also present new optical spectra of two of these objects, IRAS 05218-1212 and MCG -01-05-047. Interestingly, though both the AGNs have similar X-ray spectra, their optical spectra are completely different, adding evidence against the simplest form of the geometric unified model of AGNs. IRAS 05218-1212 appears in the optical as a Seyfert 1, despite the ∼8.5 x 10 22 cm -2 line-of-sight absorbing column indicated by its X-ray spectrum. MCG -01-05-047's optical spectrum shows no sign of AGN activity; it appears as a normal galaxy.

  2. Energy and intensity distributions of 0.279 MeV multiply Compton-scattered photons in soldering material

    International Nuclear Information System (INIS)

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

    2007-01-01

    An inverse response matrix converts the observed pulse-height distribution of a NaI(Tl) scintillation detector to a photon spectrum. This also results in extraction of intensity distribution of multiply scattered events originating from interactions of 0.279 MeV photons with thick targets of soldering material. The observed pulse-height distributions are a composite of singly and multiply scattered events in addition to bremmstrahlung-and Rayleigh-scattered events. To evaluate the contribution of multiply scattered events, the spectrum of singly scattered events contributing to inelastic Compton peak is reconstructed analytically. The optimum thickness (saturation depth), at which the number of multiply scattered events saturates, has been measured. Monte Carlo calculations also support the present results

  3. The hydrogen anomaly problem in neutron Compton scattering

    Science.gov (United States)

    Karlsson, Erik B.

    2018-03-01

    Neutron Compton scattering (also called ‘deep inelastic scattering of neutrons’, DINS) is a method used to study momentum distributions of light atoms in solids and liquids. It has been employed extensively since the start-up of intense pulsed neutron sources about 25 years ago. The information lies primarily in the width and shape of the Compton profile and not in the absolute intensity of the Compton peaks. It was therefore not immediately recognized that the relative intensities of Compton peaks arising from scattering on different isotopes did not always agree with values expected from standard neutron cross-section tables. The discrepancies were particularly large for scattering on protons, a phenomenon that became known as ‘the hydrogen anomaly problem’. The present paper is a review of the discovery, experimental tests to prove or disprove the existence of the hydrogen anomaly and discussions concerning its origin. It covers a twenty-year-long history of experimentation, theoretical treatments and discussions. The problem is of fundamental interest, since it involves quantum phenomena on the subfemtosecond time scale, which are not visible in conventional thermal neutron scattering but are important in Compton scattering where neutrons have two orders of magnitude times higher energy. Different H-containing systems show different cross-section deficiencies and when the scattering processes are followed on the femtosecond time scale the cross-section losses disappear on different characteristic time scales for each H-environment. The last section of this review reproduces results from published papers based on quantum interference in scattering on identical particles (proton or deuteron pairs or clusters), which have given a quantitative theoretical explanation both regarding the H-cross-section reduction and its time dependence. Some new explanations are added and the concluding chapter summarizes the conditions for observing the specific quantum

  4. Compton Polarimetry at ELSA

    International Nuclear Information System (INIS)

    Hillert, Wolfgang; Aurand, Bastian; Wittschen, Juergen

    2009-01-01

    Part of the future polarization program performed at the Bonn accelerator facility ELSA will rely on precision Compton polarimetry of the stored transversely polarized electron beam. Precise and fast polarimetry poses high demands on the light source and the detector which were studied in detail performing numerical simulations of the Compton scattering process. In order to experimentally verify these calculations, first measurements were carried out using an argon ion laser as light source and a prototype version of a counting silicon microstrip detector. Calculated and measured intensity profiles of backscattered photons are presented and compared, showing excellent agreement. Background originating from beam gas radiation turned out to be the major limitation of the polarimeter performance. In order to improve the situation, a new polarimeter was constructed and is currently being set up. Design and expected performance of this polarimeter upgrade are presented.

  5. The optimum lead thickness for lead-activation detectors

    International Nuclear Information System (INIS)

    Si Fenni; Hu Qingyuan

    2009-01-01

    The optimum lead thickness for lead-activation detectors has been studied in this paper. First existence of the optimum lead thickness is explained theoretically. Then the optimum lead thickness is obtained by two methods, MCNP5 calculation and mathematical estimation. At last factors which affect the optimum lead thickness are discussed. It turns out that the optimum lead thickness is irrelevant to incident neutron energies. It is recommended 2.5 cm generally.

  6. The Mathematical Foundations of 3D Compton Scatter Emission Imaging

    Directory of Open Access Journals (Sweden)

    T. T. Truong

    2007-01-01

    Full Text Available 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.

  7. Colour coherence in deep inelastic Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lebedev, A.I.; Vazdik, J.A. (Lebedev Physical Inst., Academy of Sciences, Moscow (USSR))

    1992-01-01

    MC simulation of Deep Inelastic Compton on proton - both QED and QCD - was performed on the basis of LUCIFER program for HERA energies. Charged hadron flow was calculated for string and independent fragmentation with different cuts on p{sub t} and x. It is shown that interjet colour coherence leads in the case of QCD Compton to the drag effects diminishing the hadron flow in the direction between quark jet and proton remnant jet. (orig.).

  8. Colour coherence in deep inelastic Compton scattering

    International Nuclear Information System (INIS)

    Lebedev, A.I.; Vazdik, J.A.

    1992-01-01

    MC simulation of Deep Inelastic Compton on proton - both QED and QCD - was performed on the basis of LUCIFER program for HERA energies. Charged hadron flow was calculated for string and independent fragmentation with different cuts on p t and x. It is shown that interjet colour coherence leads in the case of QCD Compton to the drag effects diminishing the hadron flow in the direction between quark jet and proton remnant jet. (orig.)

  9. 'PET -Compton' system. Comparative evaluation with PET system using Monte Carlo simulation

    International Nuclear Information System (INIS)

    Diaz Garcia, Angelina; Arista Romeu, Eduardo; Abreu Alfonso, Yamiel; Leyva Fabelo, Antonio; Pinnera Hernandez, Ibrahin; Bolannos Perez, Lourdes; Rubio Rodriguez, Juan A; Perez Morales, Jose M.; Arce Dubois, Pedro; Vela Morales, Oscar; Willmott Zappacosta, Carlos

    2011-01-01

    Positron Emission Tomography (PET) in small animals has actually achieved spatial resolution round about 1 mm and currently there are under study different approaches to improve this spatial resolution. One of them combines PET technology with Compton Cameras. This paper presents the idea of the so called 'PET-Compton' systems and includes comparative evaluation of spatial resolution and global efficiency in both PET and PET-Compton system by means of Monte Carlo simulations using Geant4 code. Simulation is done on a PET-Compton system consisting of LYSO-LuYAP scintillating detectors of particular small animal PET scanner named 'Clear-PET' and for Compton detectors based on CdZnTe semiconductor. A group of radionuclides that emits a positron (e + ) and γ quantum almost simultaneously and fulfills some selection criteria for their possible use in PET-Compton systems for medical and biological applications were studied under simulation conditions. (Author)

  10. Recent results from the Compton Observatory

    Energy Technology Data Exchange (ETDEWEB)

    Michelson, P.F.; Hansen, W.W. [Stanford Univ., CA (United States)

    1994-12-01

    The Compton Observatory is an orbiting astronomical observatory for gamma-ray astronomy that covers the energy range from about 30 keV to 30 GeV. The Energetic Gamma Ray Experiment Telescope (EGRET), one of four instruments on-board, is capable of detecting and imaging gamma radiation from cosmic sources in the energy range from approximately 20 MeV to 30 GeV. After about one month of tests and calibration following the April 1991 launch, a 15-month all sky survey was begun. This survey is now complete and the Compton Observatory is well into Phase II of its observing program which includes guest investigator observations. Among the highlights from the all-sky survey discussed in this presentation are the following: detection of five pulsars with emission above 100 MeV; detection of more than 24 active galaxies, the most distant at redshift greater than two; detection of many high latitude, unidentified gamma-ray sources, some showing significant time variability; detection of at least two high energy gamma-ray bursts, with emission in one case extending to at least 1 GeV. EGRET has also detected gamma-ray emission from solar flares up to energies of at least 2 GeV and has observed gamma-rays from the Large Magellanic Cloud.

  11. Development of TOF-PET using Compton scattering by plastic scintillators

    International Nuclear Information System (INIS)

    Kuramoto, M.; Nakamori, T.; Kimura, S.; Gunji, S.; Takakura, M.; Kataoka, J.

    2017-01-01

    We propose a time-of-flight (TOF) technique using plastic scintillators which have fast decay time of a few ns for positron emission tomography (PET). While the photoelectric absorption probability of the plastic for 511 keV gamma rays are extremely low due to its small density and effective atomic number, the cross section of Compton scattering is comparable to that of absorption by conventional inorganic scintillators. We thus propose TOF-PET using Compton scattering with plastic scintillators (Compton-PET), and performed fundamental experiments towards exploration of the Compton-PET capability. We demonstrated that the plastic scintillators achieved the better time resolution in comparison to LYSO(Ce) and GAGG(Ce) scintillators. In addition we evaluated the depth-of-interaction resolving capability with the plastic scintillators.

  12. Development of TOF-PET using Compton scattering by plastic scintillators

    Energy Technology Data Exchange (ETDEWEB)

    Kuramoto, M., E-mail: kuramoto@maxwell.kj.yamagata-u.ac.jp [Yamagata University, Kojirakawa 1-4-12, Yamagata 990-8560 (Japan); Nakamori, T., E-mail: nakamori@maxwell.kj.yamagata-u.ac.jp [Yamagata University, Kojirakawa 1-4-12, Yamagata 990-8560 (Japan); Kimura, S.; Gunji, S.; Takakura, M. [Yamagata University, Kojirakawa 1-4-12, Yamagata 990-8560 (Japan); Kataoka, J. [Waseda University, Okubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan)

    2017-02-11

    We propose a time-of-flight (TOF) technique using plastic scintillators which have fast decay time of a few ns for positron emission tomography (PET). While the photoelectric absorption probability of the plastic for 511 keV gamma rays are extremely low due to its small density and effective atomic number, the cross section of Compton scattering is comparable to that of absorption by conventional inorganic scintillators. We thus propose TOF-PET using Compton scattering with plastic scintillators (Compton-PET), and performed fundamental experiments towards exploration of the Compton-PET capability. We demonstrated that the plastic scintillators achieved the better time resolution in comparison to LYSO(Ce) and GAGG(Ce) scintillators. In addition we evaluated the depth-of-interaction resolving capability with the plastic scintillators.

  13. Development of TOF-PET using Compton scattering by plastic scintillators

    Science.gov (United States)

    Kuramoto, M.; Nakamori, T.; Kimura, S.; Gunji, S.; Takakura, M.; Kataoka, J.

    2017-02-01

    We propose a time-of-flight (TOF) technique using plastic scintillators which have fast decay time of a few ns for positron emission tomography (PET). While the photoelectric absorption probability of the plastic for 511 keV gamma rays are extremely low due to its small density and effective atomic number, the cross section of Compton scattering is comparable to that of absorption by conventional inorganic scintillators. We thus propose TOF-PET using Compton scattering with plastic scintillators (Compton-PET), and performed fundamental experiments towards exploration of the Compton-PET capability. We demonstrated that the plastic scintillators achieved the better time resolution in comparison to LYSO(Ce) and GAGG(Ce) scintillators. In addition we evaluated the depth-of-interaction resolving capability with the plastic scintillators.

  14. A Compton camera application for the GAMOS GEANT4-based framework

    Energy Technology Data Exchange (ETDEWEB)

    Harkness, L.J., E-mail: ljh@ns.ph.liv.ac.uk [Oliver Lodge Laboratory, The University of Liverpool, Liverpool L69 7ZE (United Kingdom); Arce, P. [Department of Basic Research, CIEMAT, Madrid (Spain); 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. [Oliver Lodge Laboratory, The University of Liverpool, Liverpool L69 7ZE (United Kingdom); Lazarus, I.; Simpson, J. [STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (United Kingdom)

    2012-04-11

    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.

  15. PET-COMPTON System. Comparative evaluation with PET System using Monte Carlo Simulation

    International Nuclear Information System (INIS)

    Diaz Garcia, Angelina; Arista Romeu, Eduardo; Abreu Alfonso, Yamiel; Leyva Fabelo, Antonio; Pinnera HernAndez, Ibrahin; Bolannos Perez, Lourdes; Rubio Rodriguez, Juan A.; Perez Morales, Jose M.; Arce Dubois, Pedro; Vela Morales, Oscar; Willmott Zappacosta, Carlos

    2012-01-01

    Positron Emission Tomography (PET) in small animals has actually achieved spatial resolution round about 1 mm and currently there are under study different approaches to improve this spatial resolution. One of them combines PET technology with Compton Cameras. This paper presents the idea of the so called PET-Compton systems and has included comparative evaluation of spatial resolution and global efficiency in both PET and PET-Compton system by means of Monte Carlo simulations using Geant4 code. Simulation was done on a PET-Compton system made-up of LYSO-LuYAP scintillating detectors of particular small animal PET scanner named Clear-PET and for Compton detectors based on CdZnTe semiconductor. A group of radionuclides that emits a positron (e+) and quantum almost simultaneously and fulfills some selection criteria for their possible use in PET-Compton systems for medical and biological applications were studied under simulation conditions. By means of analytical reconstruction using SSRB (Single Slide Rebinning) method were obtained superior spatial resolution in PET-Compton system for all tested radionuclides (reaching sub-millimeter values of for 22Na source). However this analysis done by simulation have shown limited global efficiency values in PET-Compton system (in the order of 10 -5 -10 -6 %) instead of values around 5*10 -1 % that have been achieved in PET system. (author)

  16. Recent results from a Si/CdTe semiconductor Compton telescope

    International Nuclear Information System (INIS)

    Tanaka, Takaaki; Watanabe, Shin; Takeda, Shin'ichiro; Oonuki, Kousuke; Mitani, Takefumi; Nakazawa, Kazuhiro; Takashima, Takeshi; Takahashi, Tadayuki; Tajima, Hiroyasu; Sawamoto, Naoyuki; Fukazawa, Yasushi; Nomachi, Masaharu

    2006-01-01

    We are developing a Compton telescope based on high-resolution Si and CdTe detectors for astrophysical observations in sub-MeV/MeV gamma-ray region. Recently, we constructed a prototype Compton telescope which consists of six layers of double-sided Si strip detectors (DSSDs) and CdTe pixel detectors to demonstrate the basic performance of this new technology. By irradiating the detector with gamma rays from radio isotope sources, we have succeeded in Compton reconstruction of images and spectra. The obtained angular resolution is 3.9 o (FWHM) at 511keV, and the energy resolution is 14keV (FWHM) at the same energy. In addition to the conventional Compton reconstruction, i.e., drawing cones in the sky, we also demonstrated a full reconstruction by tracking Compton recoil electrons using the signals detected in successive Si layers. By irradiating 137 Cs source, we successfully obtained an image and a spectrum of 662keV line emission with this method. As a next step, development of larger DSSDs with a size of 4cmx4cm is under way to improve the effective area of the Compton telescope. We are also developing a new low-noise analog ASIC to handle the increasing number of channels. Initial results from these two new technologies are presented in this paper as well

  17. Constraint on Parameters of Inverse Compton Scattering Model for ...

    Indian Academy of Sciences (India)

    B2319+60, two parameters of inverse Compton scattering model, the initial Lorentz factor and the factor of energy loss of relativistic particles are constrained. Key words. Pulsar—inverse Compton scattering—emission mechanism. 1. Introduction. Among various kinds of models for pulsar radio emission, the inverse ...

  18. Angle-averaged Compton cross sections

    International Nuclear Information System (INIS)

    Nickel, G.H.

    1983-01-01

    The scattering of a photon by an individual free electron is characterized by six quantities: α = initial photon energy in units of m 0 c 2 ; α/sub s/ = scattered photon energy in units of m 0 c 2 ; β = initial electron velocity in units of c; phi = angle between photon direction and electron direction in the laboratory frame (LF); theta = polar angle change due to Compton scattering, measured in the electron rest frame (ERF); and tau = azimuthal angle change in the ERF. We present an analytic expression for the average of the Compton cross section over phi, theta, and tau. The lowest order approximation to this equation is reasonably accurate for photons and electrons with energies of many keV

  19. Angle-averaged Compton cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Nickel, G.H.

    1983-01-01

    The scattering of a photon by an individual free electron is characterized by six quantities: ..cap alpha.. = initial photon energy in units of m/sub 0/c/sup 2/; ..cap alpha../sub s/ = scattered photon energy in units of m/sub 0/c/sup 2/; ..beta.. = initial electron velocity in units of c; phi = angle between photon direction and electron direction in the laboratory frame (LF); theta = polar angle change due to Compton scattering, measured in the electron rest frame (ERF); and tau = azimuthal angle change in the ERF. We present an analytic expression for the average of the Compton cross section over phi, theta, and tau. The lowest order approximation to this equation is reasonably accurate for photons and electrons with energies of many keV.

  20. Design of a Compton camera for 3D prompt-{gamma} imaging during ion beam therapy

    Energy Technology Data Exchange (ETDEWEB)

    Roellinghoff, F., E-mail: roelling@ipnl.in2p3.fr [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Richard, M.-H., E-mail: mrichard@ipnl.in2p3.fr [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Chevallier, M.; Constanzo, J.; Dauvergne, D. [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); Freud, N. [INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Henriquet, P.; Le Foulher, F. [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); Letang, J.M. [INSA-Lyon Laboratory of Nondestructive Testing using Ionizing Radiation (CNDRI), F-69621 Villeurbanne Cedex (France); Montarou, G. [LPC, CNRS/IN2P3, Clermont-F. University (France); Ray, C.; Testa, E.; Testa, M. [Universite de Lyon, F-69622 Lyon (France); Universite Lyon 1 and CNRS/IN2P3, UMR 5822, IPNL, F-69622 Villeurbanne (France); Walenta, A.H. [Uni-Siegen, FB Physik, Emmy-Noether Campus, D-57068 Siegen (Germany)

    2011-08-21

    We investigate, by means of Geant4 simulations, a real-time method to control the position of the Bragg peak during ion therapy, based on a Compton camera in combination with a beam tagging device (hodoscope) in order to detect the prompt gamma emitted during nuclear fragmentation. The proposed set-up consists of a stack of 2 mm thick silicon strip detectors and a LYSO absorber detector. The {gamma} emission points are reconstructed analytically by intersecting the ion trajectories given by the beam hodoscope and the Compton cones given by the camera. The camera response to a polychromatic point source in air is analyzed with regard to both spatial resolution and detection efficiency. Various geometrical configurations of the camera have been tested. In the proposed configuration, for a typical polychromatic photon point source, the spatial resolution of the camera is about 8.3 mm FWHM and the detection efficiency 2.5x10{sup -4} (reconstructable photons/emitted photons in 4{pi}). Finally, the clinical applicability of our system is considered and possible starting points for further developments of a prototype are discussed.

  1. Time-independent inverse compton spectrum for photons from a ...

    African Journals Online (AJOL)

    The general theoretical aspects of inverse Compton scattering was investigated and an equation for the timeindependent inverse Compton spectrum for photons from a plasma cloud of finite extent was derived. This was done by convolving the Kompaneets equation used for describing the evolution of the photon spectrum ...

  2. Describing Compton scattering and two-quanta positron annihilation based on Compton profiles: Two models suited for the Monte Carlo method

    CERN Document Server

    Bohlen, TT; Patera, V; Sala, P R

    2012-01-01

    An accurate description of the basic physics processes of Compton scattering and positron annihilation in matter requires the consideration of atomic shell structure effects and, in specific, the momentum distributions of the atomic electrons. Two algorithms which model Compton scattering and two-quanta positron annihilation at rest accounting for shell structure effects are proposed. Two-quanta positron annihilation is a physics process which is of particular importance for applications such as positron emission tomography (PET). Both models use a detailed description of the processes which incorporate consistently Doppler broadening and binding effects. This together with the relatively low level of complexity of the models makes them particularly suited to be employed by fast sampling methods for Monte Carlo particle transport. Momentum distributions of shell electrons are obtained from parametrized one-electron Compton profiles. For conduction electrons, momentum distributions are derived in the framework...

  3. Compton scattering at high intensities

    Energy Technology Data Exchange (ETDEWEB)

    Heinzl, Thomas, E-mail: thomas.heinzl@plymouth.ac.u [University of Plymouth, School of Mathematics and Statistics, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2009-12-01

    High-intensity Compton scattering takes place when an electron beam is brought into collision with a high power laser. We briefly review the main intensity signatures using the formalism of strong-field quantum electrodynamics.

  4. Compton radiography, 1

    International Nuclear Information System (INIS)

    Okuyama, Shinichi; Sera, Koichiro; Fukuda, Hiroshi; Shishido, Fumio; Matsuzawa, Taiju

    1977-01-01

    Tomographic images of an object are obtainable by irradiating it with a collimated beam of monochromatic gamma rays and recording the resultant Compton rays scattered upward at right angles. This is the scattered-ray principle of the formation of a radiation image that differs from the traditional ''silhouette principle'' of radiography, and that bears prospects of stereopsis as well as cross-section tomography. (Evans, J.)

  5. The Compton polarimeter at ELSA

    International Nuclear Information System (INIS)

    Doll, D.

    1998-06-01

    In order to measure the degree of transverse polarization of the stored electron beam in the Electron Stretcher Accelerator ELSA a compton polarimeter is built up. The measurement is based on the polarization dependent cross section for the compton scattering of circular polarized photons off polarized electrons. Using a high power laser beam and detecting the scattered photons a measuring time of two minutes with a statistical error of 5% is expected from numerical simulations. The design and the results of a computer controlled feedback system to enhance the laser beam stability at the interaction point in ELSA are presented. The detection of the scattered photons is based on a lead converter and a silicon-microstrip detector. The design and test results of the detector module including readout electronic and computer control are discussed. (orig.)

  6. Study of Compton scattering influence in cardiac SPECT images

    International Nuclear Information System (INIS)

    Munhoz, A.C.L.; Abe, R.; Zanardo, E.L.; Robilotta, C.C.

    1992-01-01

    The reduction effect from Compton fraction in the quality of and image is evaluated, with two ways of acquisition data: one, with the window of energetic analyser dislocated over the photopeak and the other, with two windows, one over the Compton contribution and the other, placed in the center over the photopeak. (C.G.C.)

  7. Study of Compton broadening due to electron-photon scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao M.

    2010-01-01

    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radia­tion field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation. The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons. It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle. We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  8. Study of Compton Broadening Due to Electron-Photon Scattering

    Directory of Open Access Journals (Sweden)

    Srinivasa Rao, M.

    2010-06-01

    Full Text Available We have investigated the effects of Compton broadening due to electron-photon scattering in hot stellar atmospheres. A purely electron-photon scattering media is assumed to have plane parallel geometry with an input radiation field localized on one side of the slab. The method is based on the discrete space theory of radiative transfer for the intensity of emitted radiation.The solution is developed to study the importance of scattering of radiation by free electrons in high temperature stellar atmospheres which produces a brodening and shift in spectral lines because of the Compton effect and the Doppler effect arising from mass and thermal motions of scattering electrons.It is noticed that the Comptonized spectrum depends on three parameters: the optical depth of the medium, the temperature of the thermal electrons and the viewing angle.We also showed that the Compton effect produces red shift and asymmetry in the line. These two effects increase as the optical depth increases. It is also noticed that the emergent specific intensities become completely asymmetric for higher optical depths.

  9. Nucleon structure study by virtual compton scattering

    International Nuclear Information System (INIS)

    Berthot, J.; Bertin, P.Y.; Breton, V.; Fonvielle, H.; Hyde-Wright, C.; Quemener, G.; Ravel, O.; Braghieri, A.; Pedroni, P.; Boeglin, W.U.; Boehm, R.; Distler, M.; Edelhoff, R.; Friedrich, J.; Geiges, R.; Jennewein, P.; Kahrau, M.; Korn, M.; Kramer, H.; Krygier, K.W.; Kunde, V.; Liesenfeld, A.; Merle, K.; Neuhausen, R.; Offermann, E.A.J.M.; Pospischil, T.; Rosner, G.; Sauer, P.; Schmieden, H.; Schardt, S.; Tamas, G.; Wagner, A.; Walcher, T.; Wolf, S.

    1995-01-01

    We propose to study nucleon structure by Virtual Compton Scattering using the reaction p(e,e'p)γ with the MAMI facility. We will detect the scattered electron and the recoil proton in coincidence in the high resolution spectrometers of the hall A1. Compton events will be separated from the other channels (principally π 0 production) by missing-mass reconstruction. We plan to investigate this reaction near threshold. Our goal is to measure new electromagnetic observables which generalize the usual magnetic and electric polarizabilities. (authors). 9 refs., 18 figs., 7 tabs

  10. Importance of Doppler broadening in Compton scatter imaging techniques

    Science.gov (United States)

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

    2001-12-01

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

  11. From neutron Compton profiles to momentum distribution: Assessment of direct numerical determination

    International Nuclear Information System (INIS)

    Senesi, R.; Flammini, D.; Romanelli, G.; Andreani, C.

    2013-01-01

    Inelastic neutron scattering at high momentum transfers, in the neutron Compton scattering regime, provides an access to the neutron Compton profiles, the analogous of Compton profiles in X-ray scattering. The line shape analysis of the neutron Compton profiles is usually carried out making use of multiparametric nonlinear fitting, garnering detailed information about the momentum distribution of the target atoms. This paper presents the proposal to directly determine numerically the momentum distribution from the profiles, thus eliminating the possible instabilities present in multiparametric fitting. A comparison with Monte Carlo simulations and with previous measurements on polycrystalline ice provides quantitative assessments of the proposed method

  12. Helium Compton Form Factor Measurements at CLAS

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-07-01

    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.

  13. Development of double-sided silicon strip detectors (DSSD) for a Compton telescope

    International Nuclear Information System (INIS)

    Takeda, Shin'ichiro; Watanabe, Shin; Tanaka, Takaaki; Nakazawa, Kazuhiro; Takahashi, Tadayuki; Fukazawa, Yasushi; Yasuda, Hajimu; Tajima, Hiroyasu; Kuroda, Yoshikatsu; Onishi, Mitsunobu; Genba, Kei

    2007-01-01

    The low noise double-sided silicon strip detector (DSSD) technology is used to construct a next generation Compton telescope which is required to have both high-energy resolution and high-Compton reconstruction efficiency. In this paper, we present the result of a newly designed stacked DSSD module with high-energy resolution in highly packed mechanical structure. The system is designed to obtain good P-side and N-side noise performance by means of DC-coupled read-out. Since there are no decoupling capacitors in front-end electronics before the read-out ASICs, a high density stacked module with a pitch of 2 mm can be constructed. By using a prototype with four-layer of DSSDs with an area of 2.56cmx2.56cm, we have succeeded to operate the system. The energy resolution at 59.5 keV is measured to be 1.6 keV (FWHM) for the P-side and 2.8 keV (FWHM) for the N-side, respectively. In addition to the DSSD used in the prototype, a 4 cm wide DSSD with a thickness of 300μm is also developed. With this device, an energy resolution of 1.5 keV (FWHM) was obtained. A method to model the detector energy response to properly handle split events is also discussed

  14. Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron bunch

    Energy Technology Data Exchange (ETDEWEB)

    Kojima, Sadaoki, E-mail: kojima-s@ile.osaka-u.ac.jp; Arikawa, Yasunobu; Zhang, Zhe; Ikenouchi, Takahito; Morace, Alessio; Nagai, Takahiro; Abe, Yuki; Sakata, Shouhei; Inoue, Hiroaki; Utsugi, Masaru; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Fujioka, Shinsuke; Azechi, Hiroshi [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishimura, Yasuhiko; Togawa, Hiromi [Toyota Technical Development Corporation, 1-21 Imae, Hanamoto-cho, Toyota, Aichi 470-0334 (Japan); Ozaki, Tetsuo [National Institute for Fusion Science, 322-6 Oroshicho, Toki, Gifu 509-5292 (Japan); Kato, Ryukou [The Institute of Science and Industrial Research, Osaka University, 2-6 Yamada-oka, Suita, Osaka (Japan)

    2014-11-15

    A Compton-scattering-based X-ray spectrometer is developed to obtain the energy distribution of fast electrons produced by intense laser and matter interactions. Bremsstrahlung X-rays generated by fast electrons in a material are used to measure fast electrons’ energy distribution in matter. In the Compton X-ray spectrometer, X-rays are converted into recoil electrons by Compton scattering in a converter made from fused silica glass, and a magnet-based electron energy analyzer is used to measure the energy distribution of the electrons that recoil in the direction of the incident X-rays. The spectrum of the incident X-rays is reconstructed from the energy distribution of the recoil electrons. The accuracy of this spectrometer is evaluated using a quasi-monoenergetic 6 MeV electron bunch that emanates from a linear accelerator. An electron bunch is injected into a 1.5 mm thick tungsten plate to produce bremsstrahlung X-rays. The spectrum of these bremsstrahlung X-rays is obtained in the range from 1 to 9 MeV. The energy of the electrons in the bunch is estimated using a Monte Carlo simulation of particle-matter interactions. The result shows that the spectrometer's energy accuracy is ±0.5 MeV for 6.0 MeV electrons.

  15. Comptonization effects in spherical accretion onto black holes

    International Nuclear Information System (INIS)

    Ipser, J.R.; Price, R.H.

    1983-01-01

    For spherical accretion of gas onto a black hole, dissipative heating (from magnetic reconnection), dissipation of turbulence, etc.) leads at high accretion rates to densities and temperatures at which Comptonization unavoidably plays an important role, both in determining gas temperature and in forming the emergent spectrum. A careful and reliable treatment of the interaction of the gas with the radiation field is greatly complicated by the necessity of dealing with the essentially nonlocal nature of Comptonization. We limit ourselves here to finding approximate descriptions of some observational features of such astrophysical objects with a simple, yet justifiable, Ansatz that evades the complexities of nonlocality. The results for accretion spectra are of interest, e.g., in connection with galactic halo objects (1--10 5 M/sub sun/). High mass (10 7 --10 10 M/sub sun/) cases are of interest as models for active galactic nuclei. In particular, a very natural connection between the ratio of luminosity to Eddington luminosity and the hardness of X-ray spectra emerges, suggesting that the observed X-ray hardness ratios of luminous sources are a consequence of those sources being more or less Eddington limited

  16. The clinical determination of absolute density in bone utilizing single and dual energy compton scattering

    International Nuclear Information System (INIS)

    Huddleston, A.L.; Weaver, J.

    1980-01-01

    Several methods important in the clinical diagnosis of skeletal diseases have been proposed for the determination of bone mass, such as photon absorptiometry, computed tomography, and neutron activation. None of these present methods provides for the determination of the physical density of bone. In the Radiological Physics Research Laboratory at the University of Virginia, the principles of Compton scattering are being investigated with the intent of determining the electron density and the physical density of human bone. A Compton-scatter densitometer has been constructed for the in vivo density determination of the femoral head. This technique utilizes of collimated low energy gamma source and detector system. The method has been tested in cadavers and in known density samples and has an accuracy of 2 %. A second densitometer has been designed for the in vivo determination of electron density of the vertebrae based upon a new technique which employs dual energy Compton scattering in the spinal column. These systems will be discussed; and the principles of dual energy Compton scatter densitometry will be presented. The importance of these isotope techniques and the feasibility of in vivo density determination in the vertebrae and femoral head will be discussed as they relate to clinical diagnosis and research. (author)

  17. Compton scattering of photons from electrons bound in light elements

    International Nuclear Information System (INIS)

    Bergstrom, P.M. Jr.

    1994-01-01

    A brief introduction to the topic of Compton scattering from bound electrons is presented. The fundamental nature of this process in understanding quantum phenomena is reviewed. Methods for accurate theoretical evaluation of the Compton scattering cross section are presented. Examples are presented for scattering of several keV photons from helium

  18. Voltmeter with Compton electrons

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, N R; Gorbics, S G; Weidenheimer, D M [Berkeley Research Associates, Springfield, VA (United States)

    1997-12-31

    A technique to measure the electron end point energy of bremsstrahlung in the MV regime using only two detectors is described. One of the detector measures the total radiation, the other filters out all except the hardest photons by looking only at their Compton electrons, whose average energy is determined with a magnetic field. (author). 4 figs., 2 refs.

  19. Bin mode estimation methods for Compton camera imaging

    International Nuclear Information System (INIS)

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

    2014-01-01

    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

  20. Final-photon angular distributions in Compton double-ionization

    International Nuclear Information System (INIS)

    Kornberg, M.A.

    1999-01-01

    Angular distributions of the scattered-photon in two-electron ionization of helium by Compton scattering are reported. Our calculations are performed as a direct integration over Compton profiles. We show that backward scattering is adequately described using an uncorrelated final-state approximation, as compared with impulse approximation (IA) results. The relation dσ c 2+ /dΩ = R c dσ c + /dΩ is fulfilled within IA at high-photon energies, with R c the asymptotic shake-off ratio. (orig.)

  1. Nanogram determination of arsenic in biological reference materials by non-destructive Compton suppression neutron activation analysis

    International Nuclear Information System (INIS)

    Petra, M.; Landsberger, S.; Swift, G.

    1990-01-01

    Non-destructive epithermal neutron activation analysis in conjunction with Compton suppression has been applied to determine arsenic in seven biological standard reference materials from the National Institute of Standards and Technology. The accuracy is in excellent agreement with all the certified values and compilation results. For four of the materials detection limits between 1-4 ng/g were easily achieved while for three others they ranged from 18-50 ng/g. Overall analytical precision typically varied between 2-4% for five of the reference materials while for two other it was between 12-16%. These methods clearly demonstrate that through a judicious approach of anti-coincidence techniques, nanogram quantities of arsenic can be reliably determined without the need for labor intensive chemical separations. (orig.)

  2. Experimental preliminary exploration on determining grease thickness simulated by paraffin in petroleum pipelines

    International Nuclear Information System (INIS)

    Zhao Nongxiao; Arkin, Abulim; Yang Kunjie; Wang Shiheng; Shi Feiyue

    2009-01-01

    1.25 MeV γ-ray of 60 Co Compton scattering coefficient in the simple of paraffin,are measured by γ-ray energy spectrum analysis in two determining means. At the same experimental condition, we have used this scattering coefficient to determining grease thickness simulated by paraffin. The result show the average relative difference is about 1.29% for the best group. (authors)

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

    International Nuclear Information System (INIS)

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

    2008-01-01

    The gamma photons continue to soften in energy as the number of scatterings increases in the target having finite dimensions both in depth and lateral dimensions. The number of multiply scattered photons increases with an increase in target thickness, and saturates at a particular value of the target thickness known as saturation thickness (depth). The present measurements are carried out to study the energy dependence of saturation thickness of multiply scattered gamma photons from targets of various thicknesses. The scattered photons are detected by a properly shielded NaI(Tl) gamma ray detector placed at 90 deg. to the incident beam. We observe that the saturation thickness increases with increasing incident gamma photon energy. Monte Carlo calculations based upon the package developed by Bauer and Pattison [Compton scattering experiments at the HMI (1981), HMI-B 364, pp. 1-106] support the present experimental results

  4. Testing warm Comptonization models for the origin of the soft X-ray excess in AGNs

    Science.gov (United States)

    Petrucci, P.-O.; Ursini, F.; De Rosa, A.; Bianchi, S.; Cappi, M.; Matt, G.; Dadina, M.; Malzac, J.

    2018-03-01

    The X-ray spectra of many active galactic nuclei (AGNs) show a soft X-ray excess below 1-2 keV on top of the extrapolated high-energy power law. The origin of this component is uncertain. It could be a signature of relativistically blurred, ionized reflection or the high-energy tail of thermal Comptonization in a warm (kT 1 keV), optically thick (τ ≃ 10-20) corona producing the optical/UV to soft X-ray emission. The purpose of the present paper is to test the warm corona model on a statistically significant sample of unabsorbed, radio-quiet AGNs with XMM-Newton archival data, providing simultaneous optical/UV and X-ray coverage. The sample has 22 objects and 100 observations. We use two thermal Comptonization components to fit the broadband spectra, one for the warm corona emission and one for the high-energy continuum. In the optical/UV, we also include the reddening, the small blue bump, and the Galactic extinction. In the X-rays, we include a warm absorber and a neutral reflection. The model gives a good fit (reduced χ2 uniformly distributed in the 0.1-1 keV range, while the optical depth is in the range 10-40. These values are consistent with a warm corona covering a large fraction of a quasi-passive accretion disk, i.e., that mostly reprocesses the warm corona emission. The disk intrinsic emission represents no more than 20% of the disk total emission. According to this interpretation, most of the accretion power would be released in the upper layers of the accretion flow.

  5. CsI Calorimeter for a Compton-Pair Telescope

    Science.gov (United States)

    Grove, Eric J.

    We propose to build and test a hodoscopic CsI(Tl) scintillating-crystal calorimeter for a medium-energy γ-ray Compton and pair telescope. The design and technical approach for this calorimeter relies deeply on heritage from the Fermi LAT CsI Calorimeter, but it dramatically improves the low-energy performance of that design by reading out the scintillation light with silicon photomultipliers (SiPMs), making the technology developed for Fermi applicable in the Compton regime. While such a hodoscopic calorimeter is useful for an entire class of medium-energy γ-ray telescope designs, we propose to build it explicitly to support beam tests and balloon flight of the Proto-ComPair telescope, the development and construction of which was funded in a four-year APRA program beginning in 2015 ("ComPair: Steps to a Medium Energy γ-ray Mission" with PI J. McEnery of GSFC). That award did not include funding for its CsI calorimeter subsystem, and this proposal is intended to cover that gap. ComPair is a MIDEX-class instrument concept to perform a high-sensitivity survey of the γ-ray sky from 0.5 MeV to 500 MeV. ComPair is designed to provide a dramatic increase in sensitivity relative to previous instruments in this energy range (predominantly INTEGRAL/SPI and Compton COMPTEL), with the same transformative sensitivity increase - and corresponding scientific return- that the Fermi Large Area Telescope provided relative to Compton EGRET. To enable transformative science over a broad range of MeV energies and with a wide field of view, ComPair is a combined Compton telescope and pair telescope employing a silicon-strip tracker (for Compton scattering and pair conversion and tracking) and a solid-state CdZnTe calorimeter (for Compton absorption) and CsI calorimeter (for pair calorimetry), surrounded by a plastic scintillator anti-coincidence detector. Under the current proposal, we will complete the detailed design, assembly, and test of the CsI calorimeter for the risk

  6. A stacked CdTe pixel detector for a compton camera

    International Nuclear Information System (INIS)

    Oonuki, Kousuke; Tanaka, Takaaki; Watanabe, Shin; Takeda, Shin'ichiro; Nakazawa, Kazuhiro; Ushio, Masayoshi; Mitani, Takefumi; Takahashi, Tadayuki; Tajima, Hiroyasu

    2007-01-01

    We are developing a semiconductor Compton telescope to explore the universe in the energy band from several tens of keV to a few MeV. A detector material of combined Si strip and CdTe pixel is used to cover the energy range around 60keV. For energies above several hundred keV, in contrast, the higher detection efficiency of CdTe semiconductor in comparison with Si is expected to play an important role as both an absorber and a scatterer. In order to demonstrate the spectral and imaging capability of a CdTe-based Compton camera, we developed a Compton telescope consisting of a stack of CdTe pixel detectors as a small scale prototype. With this prototype, we succeeded in reconstructing images and spectra by solving the Compton kinematics within the energy band from 122 to 662keV. The energy resolution (FWHM) of reconstructed spectra is 7.3keV at 511keV. The angular resolution obtained at 511keV is measured to be 12.2 deg. (FWHM)

  7. Thickness Dependent on Photocatalytic Activity of Hematite Thin Films

    Directory of Open Access Journals (Sweden)

    Yen-Hua Chen

    2012-01-01

    Full Text Available Hematite (Fe2O3 thin films with different thicknesses are fabricated by the rf magnetron sputtering deposition. The effects of film thicknesses on the photocatalytic activity of hematite films have been investigated. Hematite films possess a polycrystalline hexagonal structure, and the band gap decreases with an increase of film thickness. Moreover, all hematite films exhibit good photocatalytic ability under visible-light irradiation; the photocatalytic activity of hematite films increases with the increasing film thickness. This is because the hematite film with a thicker thickness has a rougher surface, providing more reaction sites for photocatalysis. Another reason is a lower band gap of a hematite film would generate more electron-hole pairs under visible-light illumination to enhance photocatalytic efficiency. Experimental data are well fitted with Langmuir-Hinshelwood kinetic model. The photocatalytic rate constant of hematite films ranges from 0.052 to 0.068 min-1. This suggests that the hematite film is a superior photocatalyst under visible-light irradiation.

  8. Sensitivity booster for DOI-PET scanner by utilizing Compton scattering events between detector blocks

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Eiji, E-mail: rush@nirs.go.jp; Tashima, Hideaki; Yamaya, Taiga

    2014-11-01

    In a conventional PET scanner, coincidence events are measured with a limited energy window for detection of photoelectric events in order to reject Compton scatter events that occur in a patient, but Compton scatter events caused in detector crystals are also rejected. Scatter events within the patient causes scatter coincidences, but inter crystal scattering (ICS) events have useful information for determining an activity distribution. Some researchers have reported the feasibility of PET scanners based on a Compton camera for tracing ICS into the detector. However, these scanners require expensive semiconductor detectors for high-energy resolution. In the Anger-type block detector, single photons interacting with multiple detectors can be obtained for each interacting position and complete information can be gotten just as for photoelectric events in the single detector. ICS events in the single detector have been used to get coincidence, but single photons interacting with multiple detectors have not been used to get coincidence. In this work, we evaluated effect of sensitivity improvement using Compton kinetics in several types of DOI-PET scanners. The proposed method promises to improve the sensitivity using coincidence events of single photons interacting with multiple detectors, which are identified as the first interaction (FI). FI estimation accuracy can be improved to determine FI validity from the correlation between Compton scatter angles calculated on the coincidence line-of-response. We simulated an animal PET scanner consisting of 42 detectors. Each detector block consists of three types of scintillator crystals (LSO, GSO and GAGG). After the simulation, coincidence events are added as information for several depth-of-interaction (DOI) resolutions. From the simulation results, we concluded the proposed method promises to improve the sensitivity considerably when effective atomic number of a scintillator is low. Also, we showed that FI estimate

  9. Extraction of Generalized Parton Distributions from combined Deeply Virtual Compton Scattering and Timelike Compton scattering fits

    Science.gov (United States)

    Boer, Marie

    2017-09-01

    Generalized Parton Distributions (GPDs) contain the correlation between the parton's longitudinal momentum and their transverse distribution. They are accessed through hard exclusive processes, such as Deeply Virtual Compton Scattering (DVCS). DVCS has already been measured in several experiments and several models allow for extracting GPDs from these measurements. Timelike Compton Scattering (TCS) is, at leading order, the time-reversal equivalent process to DVCS and accesses GPDs at the same kinematics. Comparing GPDs extracted from DVCS and TCS is a unique way for proving GPD universality. Combining fits from the two processes will also allow for better constraining the GPDs. We will present our method for extracting GPDs from DVCS and TCS pseudo-data. We will compare fit results from the two processes in similar conditions and present what can be expected in term of contraints on GPDs from combined fits.

  10. THREE-YEAR SWIFT-BAT SURVEY OF ACTIVE GALACTIC NUCLEI: RECONCILING THEORY AND OBSERVATIONS?

    International Nuclear Information System (INIS)

    Burlon, D.; Greiner, J.; Merloni, A.; Ajello, M.; Comastri, A.; Gehrels, N.

    2011-01-01

    It is well accepted that unabsorbed as well as absorbed active galactic nuclei (AGNs) are needed to explain the nature and shape of the Cosmic X-ray background (CXB), even if the fraction of highly absorbed objects (dubbed Compton-thick sources) still substantially escapes detection. We derive and analyze the absorption distribution using a complete sample of AGNs detected by Swift-BAT in the first three years of the survey. The fraction of Compton-thick AGNs represents only 4.6% of the total AGN population detected by Swift-BAT. However, we show that once corrected for the bias against the detection of very absorbed sources the real intrinsic fraction of Compton-thick AGNs is 20 -6 +9 %. We proved for the first time (also in the Burst Alert Telescope (BAT) band) that the anti-correlation of the fraction of absorbed AGNs and luminosity is tightly connected to the different behavior of the X-ray luminosity functions (XLFs) of absorbed and unabsorbed AGNs. This points toward a difference between the two subsamples of objects with absorbed AGNs being, on average, intrinsically less luminous than unobscured ones. Moreover, the XLFs show that the fraction of obscured AGNs might also decrease at very low luminosity. This can be successfully interpreted in the framework of a disk cloud outflow scenario as the disappearance of the obscuring region below a critical luminosity. Our results are discussed in the framework of population synthesis models and the origin of the CXB.

  11. FRONT-END ASIC FOR A SILICON COMPTON TELESCOPE.

    Energy Technology Data Exchange (ETDEWEB)

    DE GERONIMO,G.; FRIED, J.; FROST, E.; PHLIPS, B.; VERNON, E.; WULF, E.A.

    2007-10-27

    We describe a front-end application specific integrated circuit (ASIC) developed for a silicon Compton telescope. Composed of 32 channels, it reads out signals in both polarities from each side of a Silicon strip sensor, 2 mm thick 27 cm long, characterized by a strip capacitance of 30 pF. Each front-end channel provides low-noise charge amplification, shaping with a stabilized baseline, discrimination, and peak detection with an analog memory. The channels can process events simultaneously, and the read out is sparsified. The charge amplifier makes uses a dual-cascode configuration and dual-polarity adaptive reset, The low-hysteresis discriminator and the multi-phase peak detector process signals with a dynamic range in excess of four hundred. An equivalent noise charge (ENC) below 200 electrons was measured at 30 pF, with a slope of about 4.5 electrons/pF at a peaking time of 4 {micro}s. With a total dissipated power of 5 mW the channel covers an energy range up to 3.2 MeV.

  12. Spin and orbital magnetisation densities determined by Compton scattering of photons

    International Nuclear Information System (INIS)

    Collins, S.P.; Laundy, D.; Cooper, M.J.; Lovesey, S.W.; Uppsala Univ.

    1990-03-01

    Compton scattering of a circularly polarized photon beam is shown to provide direct information on orbital and spin magnetisation densities. Experiments are reported which demonstrate the feasibility of the method by correctly predicting the ratio of spin and orbital magnetisation components in iron and cobalt. A partially polarised beam of 45 keV photons from the Daresbury Synchrotron Radiation Source produces charge-magnetic interference scattering which is measured by a field-difference method. Theory shows that the interference cross section contains the Compton profile of polarised electrons modulated by a structure factor which is a weighted sum of spin and orbital magnetisations. In particular, the scattering geometry for which the structure factor vanishes yields a unique value for the ratio of the magnetisation densities. Compton scattering, being an incoherent process, provides data on total unit cell magnetisations which can be directly compared with bulk data. In this respect, Compton scattering complements magnetic neutron and photon Bragg diffraction. (author)

  13. Compton imaging tomography for nondestructive evaluation of large multilayer aircraft components and structures

    Science.gov (United States)

    Romanov, Volodymyr; Grubsky, Victor; Zahiri, Feraidoon

    2017-02-01

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

  14. Inverse compton emission of gamma rays near the pulsar surface

    International Nuclear Information System (INIS)

    Morini, M.

    1981-01-01

    The physical conditions near pulsar surface that might give rise to gamma ray emission from Crab and Vela pulsars are not yet well understood. Here I suggest that, in the context of the vacuum discharge mechanism proposed by Ruderman and Sutherland (1975), gamma rays are produced by inverse Compton scattering of secondary electrons with the thermal radiation of the star surface as well as for curvature and synchotron radiation. It is found that inverse Compton scattering is relevant if the neutron star surface temperature is greater than 10 6 K or of the polar cap temperature is of the order of 5 x 10 6 K. Inverse Compton scattering in anisotropic photon fields and Klein-Nishina regime is here carefully considered. (orig.)

  15. Compton scattering

    International Nuclear Information System (INIS)

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A -2 based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required

  16. Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Botto, D.J.; Pratt, R.H.

    1979-05-01

    The current status of Compton scattering, both experimental observations and the theoretical predictions, is examined. Classes of experiments are distinguished and the results obtained are summarized. The validity of the incoherent scattering function approximation and the impulse approximation is discussed. These simple theoretical approaches are compared with predictions of the nonrelativistic dipole formula of Gavrila and with the relativistic results of Whittingham. It is noted that the A/sup -2/ based approximations fail to predict resonances and an infrared divergence, both of which have been observed. It appears that at present the various available theoretical approaches differ significantly in their predictions and that further and more systematic work is required.

  17. Advanced Source Deconvolution Methods for Compton Telescopes

    Science.gov (United States)

    Zoglauer, Andreas

    The next generation of space telescopes utilizing Compton scattering for astrophysical observations is destined to one day unravel the mysteries behind Galactic nucleosynthesis, to determine the origin of the positron annihilation excess near the Galactic center, and to uncover the hidden emission mechanisms behind gamma-ray bursts. Besides astrophysics, Compton telescopes are establishing themselves in heliophysics, planetary sciences, medical imaging, accelerator physics, and environmental monitoring. Since the COMPTEL days, great advances in the achievable energy and position resolution were possible, creating an extremely vast, but also extremely sparsely sampled data space. Unfortunately, the optimum way to analyze the data from the next generation of Compton telescopes has not yet been found, which can retrieve all source parameters (location, spectrum, polarization, flux) and achieves the best possible resolution and sensitivity at the same time. This is especially important for all sciences objectives looking at the inner Galaxy: the large amount of expected sources, the high background (internal and Galactic diffuse emission), and the limited angular resolution, make it the most taxing case for data analysis. In general, two key challenges exist: First, what are the best data space representations to answer the specific science questions? Second, what is the best way to deconvolve the data to fully retrieve the source parameters? For modern Compton telescopes, the existing data space representations can either correctly reconstruct the absolute flux (binned mode) or achieve the best possible resolution (list-mode), both together were not possible up to now. Here we propose to develop a two-stage hybrid reconstruction method which combines the best aspects of both. Using a proof-of-concept implementation we can for the first time show that it is possible to alternate during each deconvolution step between a binned-mode approach to get the flux right and a

  18. Neutron-damaged GaAs detectors for use in a Compton spectrometer

    International Nuclear Information System (INIS)

    Kammeraad, J.E.; Sale, K.E.; Wang, C.L.; Baltrusaitis, R.M.

    1992-01-01

    Detectors made of GaAs are being studies for use on the focal plane of a Compton spectrometer which measures 1-MeV to 25-MeV gamma rays with high energy resolution (1% or 100 keV, whichever is greater) and 200-ps time resolution. The detectors are GaAs chips that have been neutron-damaged to improve the time response. The detectors will be used to measure fast transient signals in the current mode. The properties of various GaAs detector configurations are being studied by bombarding sample detectors with short pulses of 4-MeV to 16-MeV electrons at the Linac Facility at EG ampersand G Energy Measurements, Inc., Santa Barbara Operations. Measurements of detector sensitivity and impulse response versus detector bias, thickness, and electron beam energy and intensity have been performed and are presented. 5 refs

  19. Pulsar high energy emission due to inverse Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Lyutikov, Maxim

    2013-06-15

    We discuss growing evidence that pulsar high energy is emission is generated via Inverse Compton mechanism. We reproduce the broadband spectrum of Crab pulsar, from UV to very high energy gamma-rays - nearly ten decades in energy, within the framework of the cyclotron-self-Compton model. Emission is produced by two counter-streaming beams within the outer gaps, at distances above ∼ 20 NS radii. The outward moving beam produces UV-X-ray photons via Doppler-booster cyclotron emission, and GeV photons by Compton scattering the cyclotron photons produced by the inward going beam. The scattering occurs in the deep Klein-Nishina regime, whereby the IC component provides a direct measurement of particle distribution within the magnetosphere. The required plasma multiplicity is high, ∼10{sup 6} – 10{sup 7}, but is consistent with the average particle flux injected into the pulsar wind nebula.

  20. Monte Carlo Study of the Effect of Collimator Thickness on T-99m Source Response in Single Photon Emission Computed Tomography

    International Nuclear Information System (INIS)

    Islamian, Jalil Pirayesh; Toossi, Mohammad Taghi Bahreyni; Momennezhad, Mahdi; Zakavi, Seyyed Rasoul; Sadeghi, Ramin; Ljungberg, Michael

    2012-01-01

    In single photon emission computed tomography (SPECT), the collimator is a crucial element of the imaging chain and controls the noise resolution tradeoff of the collected data. The current study is an evaluation of the effects of different thicknesses of a low-energy high-resolution (LEHR) collimator on tomographic spatial resolution in SPECT. In the present study, the SIMIND Monte Carlo program was used to simulate a SPECT equipped with an LEHR collimator. A point source of 99m Tc and an acrylic cylindrical Jaszczak phantom, with cold spheres and rods, and a human anthropomorphic torso phantom (4D-NCAT phantom) were used. Simulated planar images and reconstructed tomographic images were evaluated both qualitatively and quantitatively. According to the tabulated calculated detector parameters, contribution of Compton scattering, photoelectric reactions, and also peak to Compton (P/C) area in the obtained energy spectrums (from scanning of the sources with 11 collimator thicknesses, ranging from 2.400 to 2.410 cm), we concluded the thickness of 2.405 cm as the proper LEHR parallel hole collimator thickness. The image quality analyses by structural similarity index (SSIM) algorithm and also by visual inspection showed suitable quality images obtained with a collimator thickness of 2.405 cm. There was a suitable quality and also performance parameters’ analysis results for the projections and reconstructed images prepared with a 2.405 cm LEHR collimator thickness compared with the other collimator thicknesses

  1. Doppler Broadening Calculations of Compton Scattering for Molecules, Plastics, Tissues, and Few Biological Materials in the X-Ray Region: An Analysis in Terms of Compton Broadening and Geometrical Energy Broadening

    Science.gov (United States)

    Rao, D. V.; Cesareo, R.; Brunetti, A.; Gigante, G. E.; Akatsuka, T.; Takeda, T.; Itai, Y.

    2004-09-01

    Relativistic and nonrelativistic Compton profile cross sections for H, C, N, O, P, and Ca and for a few important biological materials such as water, polyethylene, lucite, polystyrene, nylon, polycarbonate, bakelite, fat, bone and calcium hydroxyapatite are estimated for a number of Kα x-ray energies and for 59.54 keV (Am-241) γ photons. Energy broadening and geometrical broadening (ΔG) is estimated by assuming θmin and θmax are symmetrically situated around θ=90°. FWHM of J(PZ) and FWHM of Compton energy broadening are evaluated at various incident photon energies. These values are estimated around the centroid of the Compton profile with an energy interval of 0.1 and 1.0 keV for 59.54 keV photons. Total Compton, individual shell, and Compton energy-absorption scattering cross sections are evaluated in the energy region from 0.005 to 0.5 MeV. It is an attempt to know the effect of Doppler broadening for single atoms, many of which constitute the biological materials.

  2. Contribution of inner shell Compton ionization to the X-ray fluorescence line intensity

    Science.gov (United States)

    Fernández, Jorge E.; Scot, Viviana; Di Giulio, Eugenio

    2016-10-01

    The Compton effect is a potential ionization mechanism of atoms. It produces vacancies in inner shells that are filled with the same mechanism of atomic relaxation as the one following photo-absorption. This contribution to X-ray fluorescence emission is frequently neglected because the total Compton cross-section is apparently much lower than the photoelectric one at useful X-ray energies. However, a more careful analysis suggests that is necessary to consider single shell cross sections (instead of total cross sections) as a function of energy. In this article these Compton cross sections are computed for the shells K, L1-L3 and M1-M5 in the framework of the impulse approximation. By comparing the Compton and the photoelectric cross-section for each shell it is then possible to determine the extent of the Compton correction to the intensity of the corresponding characteristic lines. It is shown that for the K shell the correction becomes relevant for excitation energies which are too high to be influent in X-ray spectrometry. In contrast, for L and M shells the Compton contribution is relevant for medium-Z elements and medium energies. To illustrate the different grades of relevance of the correction, for each ionized shell, the energies for which the Compton contribution reaches the extent levels of 1, 5, 10, 20, 50 and 100% of the photoelectric one are determined for all the elements with Z = 11-92. For practical applications it is provided a simple formula and fitting coefficients to compute average correction levels for the shells considered.

  3. Compton suppression gamma-counting: The effect of count rate

    Science.gov (United States)

    Millard, H.T.

    1984-01-01

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

  4. Analysis of materials in ducts by Compton scattering

    International Nuclear Information System (INIS)

    Gouveia, M.A.G.; Lopes, R.T.; Jesus, E.F.O. de; Camerini, C.S.

    2000-01-01

    This work presents the use of the Compton Scattering Technique as essay, for materials characterization in petroleum ducts. The essay have been accomplished in laboratory ambit, so that the presented results should be analyzed so that the system can come to be used in the field. The inspection was performed using Compton Scattering techniques, with two detectors aligned, in an angle of 90 degrees with a source of Cs-137 with energy of 662 keV. The results demonstrated the good capacity of the system to detect materials deposited in petroleum ducts during petroleum transportation. (author)

  5. The Compton Camera - medical imaging with higher sensitivity Exhibition LEPFest 2000

    CERN Multimedia

    2000-01-01

    The Compton Camera reconstructs the origin of Compton-scattered X-rays using electronic collimation with Silicon pad detectors instead of the heavy conventional lead collimators in Anger cameras - reaching up to 200 times better sensitivity and a factor two improvement in resolution. Possible applications are in cancer diagnosis, neurology neurobiology, and cardiology.

  6. Studies of coherent/Compton scattering method for bone mineral content measurement

    International Nuclear Information System (INIS)

    Sakurai, Kiyoko; Iwanami, Shigeru; Nakazawa, Keiji; Matsubayashi, Takashi; Imamura, Keiko.

    1980-01-01

    A measurement of bone mineral content by a coherent/Compton scattering method was described. A bone sample was irradiated by a collimated narrow beam of 59.6 keV gamma-rays emitted from a 300 mCi 241 Am source, and the scattered radiations were detected using a collimated pure germanium detector placed at 90 0 to the incident beam. The ratio of coherent to Compton peaks in a spectrum of the scattered radiations depends on the bone mineral content of the bone sample. The advantage of this method is that bone mineral content of a small region in a bone can be accurately measured. Assuming that bone consists of two components, protein and bone mineral, and that the mass absorption coefficient for Compton scattering is independent of material, the coherent to Compton scattering ratio is linearly related to the percentage in weight of bone mineral. A calibration curve was obtained by measuring standard samples which were mixed with Ca 3 (PO 4 ) 2 and H 2 O. The error due to the assumption about the mass absorption coefficient for Compton scattering and to the difference between true bone and standard samples was estimated to be less than 3% within the range from 10 to 60% in weight of bone mineral. The fat in bone affects an estimated value by only 1.5% when it is 20% in weight. For the clinical application of this method, the location to be analyzed should be selected before the measurement with two X-ray images viewed from the source and the detector. These views would be also used to correct the difference in absorption between coherent and Compton scattered radiations whose energies are slightly different from each other. The absorbed dose to the analyzed region was approximately 150 mrad. The time required for one measurement in this study was about 10 minutes. (author)

  7. Computer control in a compton scattering spectrometer

    International Nuclear Information System (INIS)

    Cui Ningzhuo; Chen Tao; Gong Zhufang; Yang Baozhong; Mo Haiding; Hua Wei; Bian Zuhe

    1995-01-01

    The authors introduced the hardware and software of computer autocontrol of calibration and data acquisition in a Compton Scattering spectrometer which consists of a HPGe detector, Amplifiers and a MCA

  8. The experimental challenge of virtual compton scattering above 8 GeV

    International Nuclear Information System (INIS)

    Pierre Bertin; Yves Roblin; Charles Hyde-Wright

    1999-01-01

    We discuss the experimental issues confronting measurements of the Virtual Compton Scattering (VCS) reaction ep->ep gamma with electron beam energies 6-30 GeV. We specifically address the kinematics of Deeply Virtual Compton Scattering (Deep Inelastic Scattering, with coincident detection of the exclusive real photon nearly parallel to the virtual photon direction) and large transverse momentum VCS (High energy VCS of arbitrary Q 2 , and the recoil proton emitted with high momentum transverse to the virtual photon direction). We discuss the experimental equipment necessary for these measurements. For the DVCS, we emphasize the importance of the Bethe-Heitler-Compton interference terms that can be measured with the electron-positron (beam charge) asymmetry, and the electron beam helicity asymmetry

  9. Beam dynamics simulation in the X-ray Compton source

    International Nuclear Information System (INIS)

    Gladkikh, P.; Karnaukhov, I.; Telegin, Yu.; Shcherbakov, A.; Zelinsky, A.

    2002-01-01

    At the National Science Center 'Kharkov Institute of Physics and Technology' the X-ray source based on Compton scattering has been developed. The computer code for simulation of electron beam dynamics with taking into account the Compton scattering effect based on Monte Carlo method is described in this report. The first results of computer simulation of beam dynamics with electron-photon interaction, parameters of electron and photon beams are presented. Calculations were carried out with the lattice of synchrotron light source SRS-800 Ukrainian Synchrotron Center

  10. Beam dynamics simulation in the X-ray Compton source

    CERN Document Server

    Gladkikh, P; Telegin, Yu P; Shcherbakov, A; Zelinsky, A

    2002-01-01

    At the National Science Center 'Kharkov Institute of Physics and Technology' the X-ray source based on Compton scattering has been developed. The computer code for simulation of electron beam dynamics with taking into account the Compton scattering effect based on Monte Carlo method is described in this report. The first results of computer simulation of beam dynamics with electron-photon interaction, parameters of electron and photon beams are presented. Calculations were carried out with the lattice of synchrotron light source SRS-800 Ukrainian Synchrotron Center.

  11. On the Compton Twist-3 Asymmetries

    International Nuclear Information System (INIS)

    Korotkiyan, V.M.; Teryaev, O.V.

    1994-01-01

    The 'fermionic poles' contribution to the twist-3 single asymmetry in the gluon Compton process is calculated. The 'gluonic poles' existence seems to contradict the density matrix positivity. Qualitative predictions for the direct photon and jets asymmetries are presented. 13 refs., 2 figs

  12. Use of implicit Monte Carlo radiation transport with hydrodynamics and compton scattering

    International Nuclear Information System (INIS)

    Fleck, J.A. Jr.

    1971-03-01

    It is shown that the combination of implicit radiation transport and hydrodynamics, Compton scattering, and any other energy transport can be simply carried out by a ''splitting'' procedure. Contributions to material energy exchange can be reckoned separately for hydrodynamics, radiation transport without scattering, Compton scattering, plus any other possible energy exchange mechanism. The radiation transport phase of the calculation would be implicit, but the hydrodynamics and Compton portions would not, leading to possible time step controls. The time step restrictions which occur on radiation transfer due to large Planck mean absorption cross-sections would not occur

  13. Deeply virtual Compton scattering. Results and future

    International Nuclear Information System (INIS)

    Nowak, W.D.

    2005-03-01

    Access to generalised parton distributions (GPDs) through deeply virtual Compton scattering (DVCS) is briefly described. Presently available experimental results on DVCS are summarized in conjunction with plans for future measurements. (orig.)

  14. The first demonstration of the concept of “narrow-FOV Si/CdTe semiconductor Compton camera”

    Energy Technology Data Exchange (ETDEWEB)

    Ichinohe, Yuto, E-mail: ichinohe@astro.isas.jaxa.jp [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Uchida, Yuusuke; Watanabe, Shin [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Edahiro, Ikumi [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Hayashi, Katsuhiro [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Kawano, Takafumi; Ohno, Masanori [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Ohta, Masayuki [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Takeda, Shin' ichiro [Okinawa Institute of Science and Technology Graduate University, 1919-1 Tancha, Onna-son, Okinawa 904-0495 (Japan); Fukazawa, Yasushi [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); Katsuragawa, Miho [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Nakazawa, Kazuhiro [University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Odaka, Hirokazu [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo, Sagamihara, Kanagawa 252-5210 (Japan); Tajima, Hiroyasu [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa, Nagoya, Aichi 464-8601 (Japan); Takahashi, Hiromitsu [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8526 (Japan); and others

    2016-01-11

    The Soft Gamma-ray Detector (SGD), to be deployed on board the ASTRO-H satellite, has been developed to provide the highest sensitivity observations of celestial sources in the energy band of 60–600 keV by employing a detector concept which uses a Compton camera whose field-of-view is restricted by a BGO shield to a few degree (narrow-FOV Compton camera). In this concept, the background from outside the FOV can be heavily suppressed by constraining the incident direction of the gamma ray reconstructed by the Compton camera to be consistent with the narrow FOV. We, for the first time, demonstrate the validity of the concept using background data taken during the thermal vacuum test and the low-temperature environment test of the flight model of SGD on ground. We show that the measured background level is suppressed to less than 10% by combining the event rejection using the anti-coincidence trigger of the active BGO shield and by using Compton event reconstruction techniques. More than 75% of the signals from the field-of-view are retained against the background rejection, which clearly demonstrates the improvement of signal-to-noise ratio. The estimated effective area of 22.8 cm{sup 2} meets the mission requirement even though not all of the operational parameters of the instrument have been fully optimized yet.

  15. Monitoring of laser-accelerated particle beams for hadron therapy via Compton tracking

    Energy Technology Data Exchange (ETDEWEB)

    Lang, C.; Thirolf, P.G. [LMU, Muenchen (Germany); Habs, D.; Tajima, T. [LMU, Muenchen (Germany); MPQ, Garching (Germany); Zoglauer, A. [SSL, Berkeley (United States); Kanbach, G.; Diehl, R. [MPE, Muenchen (Germany); Schreiber, J. [MPQ, Garching (Germany)

    2011-07-01

    Presently large efforts have been achieved towards the development of hadron cancer therapy based on laser-accelerated ion (p, C) beams, particularly aiming at the treatment of small tumors (few mm size). Thus precise monitoring of the ion track is mandatory. Conventional PET technology suffers from limited signal strength and precision of locating the source position. We envisage to use Compton tracking, i.e. determining energy and momentum of Compton photons and electrons, emitted along the ion track in the irradiated soft tissue. Confining the Compton cone by tracking the scattered electron will allow to significantly improve on the position resolution. Monte Carlo simulations have been performed to characterize the achievable position resolution and efficiency of a Compton camera. We estimate a resolution of 2 mm (1 mm; 5 mm) FWHM at 2 MeV (5 MeV; 0.5 MeV). An efficiency of 1.4*10{sup -3} (4.6*10{sup -6}) at 0.5 MeV (2 MeV) is envisaged. Optimized for an energy range between 0.5 MeV and 5 MeV, we plan for a system of 5 layers of double-sided Si strip detectors (for Compton electron tracking) and an additional LaBr{sub 3}:Ce calorimeter, read out by a segmented photomultiplier tube.

  16. Characterization of CT beams using Compton spectrometry; Caracterização de feixes de TC utilizando Espectrometria Compton

    Energy Technology Data Exchange (ETDEWEB)

    Terini, Ricardo A.; Nerssissian, Denise Y.; Campelo, Maria Carolina S.; Yoshimura, Elisabeth M., E-mail: rterini@if.usp.br [Universidade de São Paulo (LDRFM/USP), SP (Brazil). Lab. de Dosimetria das Radiações e Física Médica

    2017-07-01

    Obtaining the energy spectra of computed tomography (CT) X-ray beams is essential, helping to obtain parameters that characterize beam quality and equipment performance. However, CT photon fluxes are too high to have the spectra measured directly with common photon counting detectors. In this work, a Compton spectrometer was designed, with Al-Pb-Al collimators and shields, as well as a cadmium telluride (CdTe) detector to get the spectrum of CT beams, from the measurement of the spectrum of a beam scattered at 90 deg by a polymethyl-methacrylate (PMMA) rod. A MatLab® computer code was developed, using the Waller-Hartree formalism, to reconstruct the spectrum of the incident beam, from the measured scattered beam spectrum. Tests at IF-USP Laboratory of Radiation Dosimetry and Medical Physics with standard CT beams showed that the reconstructed spectrum is alike the directly measured beam. Shielding influence and scatterer thickness were investigated. The system was tested in measurements on a GE 690 CT scanner, showing practical positioning on the exam table, and alignment with CT lasers refined by scan projection radiography. Spectra obtained with the properly shielded system presented values of half-value layer (HVL) compatible with those measured in QC tests and kVp values with accuracy to evaluate the scanner voltage calibration. (author)

  17. Compton scattering study of electron momentum distribution in lithium fluoride using 662 keV gamma radiations

    Science.gov (United States)

    Vijayakumar, R.; Shivaramu; Ramamurthy, N.; Ford, M. J.

    2008-12-01

    Here we report the first ever 137Cs Compton spectroscopy study of lithium fluoride. The spherical average Compton profiles of lithium fluoride are deduced from Compton scattering measurements on poly crystalline sample at gamma ray energy of 662 keV. To compare the experimental data, we have computed the spherical average Compton profiles using self-consistent Hartree-Fock wave functions employed on linear combination of atomic orbital (HF-LCAO) approximation. The directional Compton profiles and their anisotropic effects are also calculated using the same HF-LCAO approximation. The experimental spherical average profiles are found to be in good agreement with the corresponding HF-LCAO calculations and in qualitative agreement with Hartree-Fock free atom values. The present experimental isotropic and calculated directional profiles are also compared with the available experimental isotropic and directional Compton profiles using 59.54 and 159 keV γ-rays.

  18. The scanning Compton polarimeter for the SLD experiment

    International Nuclear Information System (INIS)

    Woods, M.

    1996-10-01

    For the 1994/95 run of the SLD experiment at SLAC, a Compton polarimeter measured the luminosity-weighted electron beam polarization to be (77.2 ± 0.5)%. This excellent accuracy is achieved by measuring the rate asymmetry of Compton-scattered electrons near the kinematic endpoint. The polarimeter takes data continuously while the electron and positron beams are in collision and achieves a statistical precision of better than 1% in a three minute run. To calibrate the polarimeter and demonstrate its accuracy, many scans are frequently done. These include scans of the laser polarization, the detector position with respect to the kinematic edge, and the laser power

  19. Geometrical effects determinant of the Compton profile shape

    International Nuclear Information System (INIS)

    Sartori, Renzo; Mainardi, R.T.

    1987-01-01

    The main purpose of this work is to evaluate the influence of the experimental set up on the shape of the Compton line. In any scattering experiment, the scattering angle is not well defined due to the collimators aperture and thus, a distribution of angles is found for each set up. This, in turn, produces the energies' distribution of the scattered photons around a mean value. This contribution has been evaluated and found it to be significant for several cases. In order to do this evaluation, a response function, that is numerically generated for each experimental set up and convoluted with the Compton profile, was defined. (Author) [es

  20. A compact Compton backscatter X-ray source for mammography and coronary angiography

    International Nuclear Information System (INIS)

    Nguyen, D.C.; Kinross-Wright, J.M.; Weber, M.E.; Volz, S.K.; Gierman, S.M.; Hayes, K.; Vernon, W.; Goldstein, D.J.

    1998-01-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The project objective is to generate a large flux of tunable, monochromatic x-rays for use in mammography and coronary angiography. The approach is based on Compton backscattering of an ultraviolet solid-state laser beam against the high-brightness 20-MeV electron beams from a compact linear accelerator. The direct Compton backscatter approach failed to produce a large flux of x-rays due to the low photon flux of the scattering solid-state laser. The authors have modified the design of a compact x-ray source to the new Compton backscattering geometry with use of a regenerative amplifier free-electron laser. They have successfully demonstrated the production of a large flux of infrared photons and a high-brightness electron beam focused in both dimensions for performing Compton backscattering in a regenerative amplifier geometry

  1. Laser-electron Compton interaction in plasma channels

    International Nuclear Information System (INIS)

    Pogorelsky, I.V.; Ben-Zvi, I.; Hirose, T.

    1998-10-01

    A concept of high intensity femtosecond laser synchrotron source (LSS) is based on Compton backscattering of focused electron and laser beams. The short Rayleigh length of the focused laser beam limits the length of interaction to a few picoseconds. However, the technology of the high repetition rate high-average power picosecond lasers required for high put through LSS applications is not developed yet. Another problem associated with the picosecond laser pulses is undesirable nonlinear effects occurring when the laser photons are concentrated in a short time interval. To avoid the nonlinear Compton scattering, the laser beam has to be split, and the required hard radiation flux is accumulated over a number of consecutive interactions that complicates the LSS design. In order to relieve the technological constraints and achieve a practically feasible high-power laser synchrotron source, the authors propose to confine the laser-electron interaction region in the extended plasma channel. This approach permits to use nanosecond laser pulses instead of the picosecond pulses. That helps to avoid the nonlinear Compton scattering regime and allows to utilize already existing technology of the high-repetition rate TEA CO 2 lasers operating at the atmospheric pressure. They demonstrate the advantages of the channeled LSS approach by the example of the prospective polarized positron source for Japan Linear Collider

  2. Compton camera study for high efficiency SPECT and benchmark with Anger system

    Science.gov (United States)

    Fontana, M.; Dauvergne, D.; Létang, J. M.; Ley, J.-L.; Testa, É.

    2017-12-01

    Single photon emission computed tomography (SPECT) is at present one of the major techniques for non-invasive diagnostics in nuclear medicine. The clinical routine is mostly based on collimated cameras, originally proposed by Hal Anger. Due to the presence of mechanical collimation, detection efficiency and energy acceptance are limited and fixed by the system’s geometrical features. In order to overcome these limitations, the application of Compton cameras for SPECT has been investigated for several years. In this study we compare a commercial SPECT-Anger device, the General Electric HealthCare Infinia system with a High Energy General Purpose (HEGP) collimator, and the Compton camera prototype under development by the French collaboration CLaRyS, through Monte Carlo simulations (GATE—GEANT4 Application for Tomographic Emission—version 7.1 and GEANT4 version 9.6, respectively). Given the possible introduction of new radio-emitters at higher energies intrinsically allowed by the Compton camera detection principle, the two detectors are exposed to point-like sources at increasing primary gamma energies, from actual isotopes already suggested for nuclear medicine applications. The Compton camera prototype is first characterized for SPECT application by studying the main parameters affecting its imaging performance: detector energy resolution and random coincidence rate. The two detector performances are then compared in terms of radial event distribution, detection efficiency and final image, obtained by gamma transmission analysis for the Anger system, and with an iterative List Mode-Maximum Likelihood Expectation Maximization (LM-MLEM) algorithm for the Compton reconstruction. The results show for the Compton camera a detection efficiency increased by a factor larger than an order of magnitude with respect to the Anger camera, associated with an enhanced spatial resolution for energies beyond 500 keV. We discuss the advantages of Compton camera application

  3. Reconstructed Image Spatial Resolution of Multiple Coincidences Compton Imager

    Science.gov (United States)

    Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

    2010-02-01

    We study the multiple coincidences Compton imager (MCCI) which is based on a simultaneous acquisition of several photons emitted in cascade from a single nuclear decay. Theoretically, this technique should provide a major improvement in localization of a single radioactive source as compared to a standard Compton camera. In this work, we investigated the performance and limitations of MCCI using Monte Carlo computer simulations. Spatial resolutions of the reconstructed point source have been studied as a function of the MCCI parameters, including geometrical dimensions and detector characteristics such as materials, energy and spatial resolutions.

  4. Beam dynamics simulation in the X-ray Compton source

    Energy Technology Data Exchange (ETDEWEB)

    Gladkikh, P.; Karnaukhov, I.; Telegin, Yu.; Shcherbakov, A. E-mail: shcherbakov@kipt.kharkov.ua; Zelinsky, A

    2002-05-01

    At the National Science Center 'Kharkov Institute of Physics and Technology' the X-ray source based on Compton scattering has been developed. The computer code for simulation of electron beam dynamics with taking into account the Compton scattering effect based on Monte Carlo method is described in this report. The first results of computer simulation of beam dynamics with electron-photon interaction, parameters of electron and photon beams are presented. Calculations were carried out with the lattice of synchrotron light source SRS-800 Ukrainian Synchrotron Center.

  5. Luminosity optimization schemes in Compton experiments based on Fabry-Perot optical resonators

    Directory of Open Access Journals (Sweden)

    Alessandro Variola

    2011-03-01

    Full Text Available The luminosity of Compton x-ray and γ sources depends on the average current in electron bunches, the energy of the laser pulses, and the geometry of the particle bunch to laser pulse collisions. To obtain high power photon pulses, these can be stacked in a passive optical resonator (Fabry-Perot cavity especially when a high average flux is required. But, in this case, owing to the presence of the optical cavity mirrors, the electron bunches have to collide at an angle with the laser pulses with a consequent luminosity decrease. In this article a crab-crossing scheme is proposed for Compton sources, based on a laser amplified in a Fabry-Perot resonator, to eliminate the luminosity losses given by the crossing angle, taking into account that in laser-electron collisions only the electron bunches can be tilted at the collision point. We report the analytical study on the crab-crossing scheme for Compton gamma sources. The analytical expression for the total yield of photons generated in Compton sources with the crab-crossing scheme of collision is derived. The optimal collision angle of the bunch was found to be equal to half of the collision angle. At this crabbing angle, the maximal yield of scattered off laser photons is attained thanks to the maximization, in the collision process, of the time spent by the laser pulse in the electron bunch. Estimations for some Compton source projects are presented. Furthermore, some schemes of the optical cavities configuration are analyzed and the luminosity calculated. As illustrated, the four-mirror two- or three-dimensional scheme is the most appropriate for Compton sources.

  6. Development of compact Compton camera for 3D image reconstruction of radioactive contamination

    Science.gov (United States)

    Sato, Y.; Terasaka, Y.; Ozawa, S.; Nakamura Miyamura, H.; Kaburagi, M.; Tanifuji, Y.; Kawabata, K.; Torii, T.

    2017-11-01

    The Fukushima Daiichi Nuclear Power Station (FDNPS), operated by Tokyo Electric Power Company Holdings, Inc., went into meltdown after the large tsunami caused by the Great East Japan Earthquake of March 11, 2011. Very large amounts of radionuclides were released from the damaged plant. Radiation distribution measurements inside FDNPS buildings are indispensable to execute decommissioning tasks in the reactor buildings. We have developed a compact Compton camera to measure the distribution of radioactive contamination inside the FDNPS buildings three-dimensionally (3D). The total weight of the Compton camera is lower than 1.0 kg. The gamma-ray sensor of the Compton camera employs Ce-doped GAGG (Gd3Al2Ga3O12) scintillators coupled with a multi-pixel photon counter. Angular correction of the detection efficiency of the Compton camera was conducted. Moreover, we developed a 3D back-projection method using the multi-angle data measured with the Compton camera. We successfully observed 3D radiation images resulting from the two 137Cs radioactive sources, and the image of the 9.2 MBq source appeared stronger than that of the 2.7 MBq source.

  7. Development of a compact scintillator-based high-resolution Compton camera for molecular imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kishimoto, A., E-mail: daphne3h-aya@ruri.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo (Japan); Kataoka, J.; Koide, A.; Sueoka, K.; Iwamoto, Y.; Taya, T. [Research Institute for Science and Engineering, Waseda University, 3-4-1 Ohkubo, Shinjuku, Tokyo (Japan); Ohsuka, S. [Central Research Laboratory, Hamamatsu Photonics K.K., 5000 Hirakuchi, Hamakita-ku, Hamamatsu, Shizuoka (Japan)

    2017-02-11

    The Compton camera, which shows gamma-ray distribution utilizing the kinematics of Compton scattering, is a promising detector capable of imaging across a wide range of energy. In this study, we aim to construct a small-animal molecular imaging system in a wide energy range by using the Compton camera. We developed a compact medical Compton camera based on a Ce-doped Gd{sub 3}Al{sub 2}Ga{sub 3}O{sub 12} (Ce:GAGG) scintillator and multi-pixel photon counter (MPPC). A basic performance confirmed that for 662 keV, the typical energy resolution was 7.4 % (FWHM) and the angular resolution was 4.5° (FWHM). We then used the medical Compton camera to conduct imaging experiments based on a 3-D imaging reconstruction algorithm using the multi-angle data acquisition method. The result confirmed that for a {sup 137}Cs point source at a distance of 4 cm, the image had a spatial resolution of 3.1 mm (FWHM). Furthermore, we succeeded in producing 3-D multi-color image of different simultaneous energy sources ({sup 22}Na [511 keV], {sup 137}Cs [662 keV], and {sup 54}Mn [834 keV]).

  8. Compton backscattered collmated X-ray source

    Science.gov (United States)

    Ruth, Ronald D.; Huang, Zhirong

    2000-01-01

    A high-intensity, inexpensive and collimated x-ray source for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications.

  9. Compton backscattered collimated x-ray source

    Science.gov (United States)

    Ruth, R.D.; Huang, Z.

    1998-10-20

    A high-intensity, inexpensive and collimated x-ray source is disclosed for applications such as x-ray lithography is disclosed. An intense pulse from a high power laser, stored in a high-finesse resonator, repetitively collides nearly head-on with and Compton backscatters off a bunched electron beam, having relatively low energy and circulating in a compact storage ring. Both the laser and the electron beams are tightly focused and matched at the interaction region inside the optical resonator. The laser-electron interaction not only gives rise to x-rays at the desired wavelength, but also cools and stabilizes the electrons against intrabeam scattering and Coulomb repulsion with each other in the storage ring. This cooling provides a compact, intense bunch of electrons suitable for many applications. In particular, a sufficient amount of x-rays can be generated by this device to make it an excellent and flexible Compton backscattered x-ray (CBX) source for high throughput x-ray lithography and many other applications. 4 figs.

  10. Stochastic Electrodynamics and the Compton effect

    International Nuclear Information System (INIS)

    Franca, H.M.; Barranco, A.V.

    1987-12-01

    Some of the main qualitative features of the Compton effect are tried to be described within the realm of Classical Stochastic Electrodynamics (SED). It is found indications that the combined action of the incident wave (frequency ω), the radiation reaction force and the zero point fluctuating electromagnetic fields of SED, are able to given a high average recoil velocity v/c=α/(1+α) to the charged particle. The estimate of the parameter α gives α ∼ ℎω/mc 2 where 2Πℎ is the constant and mc 2 is the rest energy of the particle. It is verified that this recoil is just that necessary to explain the frequency shift, observed in the scattered radiation as due to a classical double Doppler shift. The differential cross section for the radiation scattered by the recoiling charge using classical electromagnetism also calculated. The same expression as obtained by Compton in his fundamental work of 1923 is found. (author) [pt

  11. Comprehensive study of observables in Compton scattering on the nucleon

    Science.gov (United States)

    Grießhammer, Harald W.; McGovern, Judith A.; Phillips, Daniel R.

    2018-03-01

    We present an analysis of 13 observables in Compton scattering on the proton. Cross sections, asymmetries with polarised beam and/or targets, and polarisation-transfer observables are investigated for energies up to the Δ(1232) resonance to determine their sensitivity to the proton's dipole scalar and spin polarisabilities. The Chiral Effective Field Theory Compton amplitude we use is complete at N4LO, O(e2δ4), for photon energies ω˜ m_{π}, and so has an accuracy of a few per cent there. At photon energies in the resonance region, it is complete at NLO, O(e2δ0), and so its accuracy there is about 20%. We find that for energies from pion-production threshold to about 250 MeV, multiple asymmetries have significant sensitivity to presently ill-determined combinations of proton spin polarisabilities. We also argue that the broad outcomes of this analysis will be replicated in complementary theoretical approaches, e.g., dispersion relations. Finally, we show that below the pion-production threshold, 6 observables suffice to reconstruct the Compton amplitude, and above it 11 are required. Although not necessary for polarisability extractions, this opens the possibility to perform "complete" Compton-scattering experiments. An interactive Mathematica notebook, including results for the neutron, is available from judith.mcgovern@manchester.ac.uk.

  12. Hybrid coded aperture and Compton imaging using an active mask

    International Nuclear Information System (INIS)

    Schultz, L.J.; Wallace, M.S.; Galassi, M.C.; Hoover, A.S.; Mocko, M.; Palmer, D.M.; Tornga, S.R.; Kippen, R.M.; Hynes, M.V.; Toolin, M.J.; Harris, B.; McElroy, J.E.; Wakeford, D.; Lanza, R.C.; Horn, B.K.P.; Wehe, D.K.

    2009-01-01

    The trimodal imager (TMI) images gamma-ray sources from a mobile platform using both coded aperture (CA) and Compton imaging (CI) modalities. In this paper we will discuss development and performance of image reconstruction algorithms for the TMI. In order to develop algorithms in parallel with detector hardware we are using a GEANT4 [J. Allison, K. Amako, J. Apostolakis, H. Araujo, P.A. Dubois, M. Asai, G. Barrand, R. Capra, S. Chauvie, R. Chytracek, G. Cirrone, G. Cooperman, G. Cosmo, G. Cuttone, G. Daquino, et al., IEEE Trans. Nucl. Sci. NS-53 (1) (2006) 270] based simulation package to produce realistic data sets for code development. The simulation code incorporates detailed detector modeling, contributions from natural background radiation, and validation of simulation results against measured data. Maximum likelihood algorithms for both imaging methods are discussed, as well as a hybrid imaging algorithm wherein CA and CI information is fused to generate a higher fidelity reconstruction.

  13. Laser Compton Scattering Gamma Ray Induced Photo-Trasmutation

    CERN Document Server

    Li, Dazhi

    2004-01-01

    High brightness beams of gamma rays produced with laser Compton scattering have the potential to realize photo-transmutation through (γ,n) reaction, implying an efficient method to dispose long-lived fission products. Preliminary investigations have been carried out in understanding the feasibility of development of a transmutation facility to repose nuclear waste. A laser Compton scattering experimental setup based on a storage ring started to generate gamma-ray beams for studying the coupling of gamma photons and nuclear giant resonance. This paper demonstrates the dependency of nuclear transmutation efficiency on target dimensions and gamma ray features. 197Au sample was adopted in our experiment, and experimental results correspond to the theoretical estimations.

  14. Investigation of Compton effect on π-meson and charged pion polarizability

    International Nuclear Information System (INIS)

    Antipov, Yu.M.; Batarin, V.A.; Bezzubov, V.A.

    1986-01-01

    The results of an experiment aimed at the study of the 40 GeV/c pion radiative scattering on nuclei at small momentum transfers are presented. Compton effect on the pion was investigated and the charged pion polarizability was measured. The pion Compton-effect cross section dependence on the incident photon energy ω' 1 (rest pion frame) was measured in the 100 - 600 MeV range. The polarizability of charged pion from the analysis of Compton-effect events has been found to be β π =-α π =(-6.9 ± 1.4 stat. ± 1.2 syst. )x10 -43 cm 3 and the sun of pion electrical α π and magnetic β π polarizability has been estimated to be in agreement with theoretical predictions: α π +β π ≅ 0

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

    Science.gov (United States)

    Barty, C. P. J.

    2015-10-01

    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.

  16. Virtual compton scattering at low energy; Diffusion compton virtuelle a basse energie

    Energy Technology Data Exchange (ETDEWEB)

    Lhuillier, D

    1997-09-01

    The work described in this PhD is a study of the Virtual Compton scattering (VCS) off the proton at low energy, below pion production threshold. Our experiment has been carried out at MAMI in the collaboration with the help of two high resolution spectrometers. Experimentally, the VCS process is the electroproduction of photons off a liquid hydrogen target. First results of data analysis including radiative corrections are presented and compared with low energy theorem prediction. VCS is an extension of the Real Compton Scattering. The virtuality of the incoming photon allows us to access new observables of the nucleon internal structure which are complementarity to the elastic form factors: the generalized polarizabilities (GP). They are function of the squared invariant mass of the virtual photo. The mass limit of these observables restore the usual electric and magnetic polarizabilities. Our experiment is the first measurement of the VCS process at a virtual photon mass equals 0.33 Ge V square. The experimental development presents the analysis method. The high precision needed in the absolute cross-section measurement required an accurate estimate of radiative corrections to the VCS. This new calculation, which has been performed in the dimensional regulation scheme, composes the theoretical part of this thesis. At low q', preliminary results agree with low energy theorem prediction. At higher q', substraction of low energy theorem contribution to extract GP is discussed. (author)

  17. Virtual compton scattering at low energy; Diffusion compton virtuelle a basse energie

    Energy Technology Data Exchange (ETDEWEB)

    Lhuillier, D

    1997-09-01

    The work described in this PhD is a study of the Virtual Compton scattering (VCS) off the proton at low energy, below pion production threshold. Our experiment has been carried out at MAMI in the collaboration with the help of two high resolution spectrometers. Experimentally, the VCS process is the electroproduction of photons off a liquid hydrogen target. First results of data analysis including radiative corrections are presented and compared with low energy theorem prediction. VCS is an extension of the Real Compton Scattering. The virtuality of the incoming photon allows us to access new observables of the nucleon internal structure which are complementarity to the elastic form factors: the generalized polarizabilities (GP). They are function of the squared invariant mass of the virtual photo. The mass limit of these observables restore the usual electric and magnetic polarizabilities. Our experiment is the first measurement of the VCS process at a virtual photon mass equals 0.33 Ge V square. The experimental development presents the analysis method. The high precision needed in the absolute cross-section measurement required an accurate estimate of radiative corrections to the VCS. This new calculation, which has been performed in the dimensional regulation scheme, composes the theoretical part of this thesis. At low q', preliminary results agree with low energy theorem prediction. At higher q', substraction of low energy theorem contribution to extract GP is discussed. (author)

  18. A counting silicon microstrip detector for precision compton polarimetry

    CERN Document Server

    Doll, D W; Hillert, W; Krüger, H; Stammschroer, K; Wermes, N

    2002-01-01

    A detector for the detection of laser photons backscattered off an incident high-energy electron beam for precision Compton polarimetry in the 3.5 GeV electron stretcher ring ELSA at Bonn University has been developed using individual photon counting. The photon counting detector is based on a silicon microstrip detector system using dedicated ASIC chips. The produced hits by the pair converted Compton photons are accumulated rather than individually read out. A transverse profile displacement can be measured with mu m accuracy rendering a polarization measurement of the order of 1% on the time scale of 10-15 min possible.

  19. A compact X-ray source based on Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Bulyak, E.; Gladkikh, P.; Grigor' ev, Yu.; Guk, I.; Karnaukhov, I.; Khodyachikh, A.; Kononenko, S.; Mocheshnikov, N.; Mytsykov, A.; Shcherbakov, A. E-mail: shcherbakov@kipt.kharkov.ua; Tarasenko, A.; Telegin, Yu.; Zelinsky, A

    2001-07-21

    The main parameters of Kharkov electron storage ring N-100 with a beam energy range from 70 to 150 MeV are presented. The main results that were obtained in experimental researches are briefly described. The future of the N-100 upgrade to the development of the X-ray generator based on Compton back-scattering are presented. The electron beam energy range will be extended up to 250 MeV and the circumference of the storage ring will be 13.72 m. The lattice, parameters of the electron beam and the Compton back-scattering photons flux are described.

  20. A compact X-ray source based on Compton scattering

    International Nuclear Information System (INIS)

    Bulyak, E.; Gladkikh, P.; Grigor'ev, Yu.; Guk, I.; Karnaukhov, I.; Khodyachikh, A.; Kononenko, S.; Mocheshnikov, N.; Mytsykov, A.; Shcherbakov, A.; Tarasenko, A.; Telegin, Yu.; Zelinsky, A.

    2001-01-01

    The main parameters of Kharkov electron storage ring N-100 with a beam energy range from 70 to 150 MeV are presented. The main results that were obtained in experimental researches are briefly described. The future of the N-100 upgrade to the development of the X-ray generator based on Compton back-scattering are presented. The electron beam energy range will be extended up to 250 MeV and the circumference of the storage ring will be 13.72 m. The lattice, parameters of the electron beam and the Compton back-scattering photons flux are described

  1. Virtual Compton Scattering off a Spinless Target in the AdS/QCD correspondence

    Energy Technology Data Exchange (ETDEWEB)

    Wallon, Samuel [Laboratoire de Physique Theorique d' Orsay - LPT, Bat. 210, Univ. Paris-Sud 11, 91405 Orsay Cedex (France); Marquet, Cyrille [IPhT - Institut de Physique Theorique, Orme des Merisiers bat. 774, PC 136, CEA/DSM/IPhT, CEA/Saclay, F-91191 Gif-sur-Yvette Cedex (France); Roiesnel, Claude [Centre de Physique Theorique - CPHT, UMR 7644, Ecole Polytechnique, Bat. 6, RDC, F91128 Palaiseau Cedex (France)

    2010-07-01

    We study the doubly virtual Compton scattering off a spinless target {gamma}* P {yields} {gamma}* P' within the Anti-de Sitter(AdS)/QCD formalism. We find that the general structure allowed by the Lorentz invariance and gauge invariance of the Compton amplitude is not easily reproduced with the standard recipes of the AdS/QCD correspondence. In the soft-photon regime, where the semi-classical approximation is supposed to apply best, we show that the measurements of the electric and magnetic polarizabilities of a target like the charged pion in real Compton scattering, can already serve as stringent tests. (author)

  2. Increase in compton scattering of gamma rays passing along metal surface

    International Nuclear Information System (INIS)

    Grigor'ev, A.N.; Bilyk, Z.V.; Sakun, A.V.; Marushchenko, V.V.; Chernyavskij, O.Yu.; Litvinov, Yu.V.

    2014-01-01

    The paper considers experimental study of changes in energy of 137 Cs gamma source as gamma rays pass along metal surface. Decrease in gamma energy was examined by reducing the number of gamma rays in the complete absorption peak to the Compton length level and increasing the Compton effect. The number of gamma rays in the complete absorption peak decreases by 3.5 times in the angle range under study

  3. A Compton Suppressed Gamma Ray Counter For Radio Assay of Materials

    Science.gov (United States)

    Godfrey, Benjamin

    2016-03-01

    Rare event searches, such as direct dark matter experiments, require materials with ultra-low levels of natural radioactivity. We present a neutron activation analysis (NAA) technique for assaying metals, specifically titanium used for cryostat construction. Earlier attempts at NAA encountered limitations due to bulk activation via (n, p) reactions, which contributed to large continuum backgrounds due to Compton tails. Our method involves a heavy water shielded exposure to minimize (n,p) reactions and a sodium iodide shielded high purity germanium counter for the gamma ray assay. Preliminary results on assays for U/Th/K contamination in titaniumwill be presented.

  4. An in-beam Compton-suppressed Ge spectrometer for nondestructive neutron activation analysis

    International Nuclear Information System (INIS)

    Zaghloul, R.; Abd El-Haleam, A.; Mostafa, M.; Gantner, E.; Ache, H.J.

    1993-04-01

    A high-efficiency compton background suppressed gamma-ray spectrometer by anti-coincidence counting with a NaI(Tl)-shield around a central HPGe-detector for in-beam prompt gamma-ray neutron activation analysis (AC-PGNAA) using a Cf-252 neutron source has been designed and built to provide simultaneous anti-coincidence spectrometry of natural, industrial and environmental samples. The spectrometer consists of a high-purity germanium detector as the main detector and a large volume cylindrical NaI(Tl) detector as a guard detector. The assembly has the ability to measure instantaneously, simultaneously and nondestructively bulk samples up to about 50 cm 3 . Major constituent elements in several rocks and minerals such as H, B, N, Na, Mg, Al, Si, Cl, K, Ca, P, S, Ti, Fe, Sm, Nd, Mn and Gd can be determined, while oxygen cannot be measured due to its small capture cross section (0.27 mb). Several important minor and trace elements such as B, Cd and Hg beside the low residual activity, rare earths and short-lived isotopes could be detected. The sensitivity of the AC-PGNAA technique is limited by the available neutron flux at the target matrix and the neutron absorption cross section of the elements of interest. PGNAA has the advantage to estimate the constituent elements which are difficult to be measured through the delayed gamm-ray measurements such as B, Bi, C, H, P, Tl, Be, Cl and S in industrial and reference materials and those elements which are transformed into other stable isotopes when undergoing neutron capture. The design of the spectrometer assembly, its properties and performance are described

  5. Development of a Compton camera for prompt-gamma medical imaging

    Science.gov (United States)

    Aldawood, S.; Thirolf, P. G.; Miani, A.; Böhmer, M.; Dedes, G.; Gernhäuser, R.; Lang, C.; Liprandi, S.; Maier, L.; Marinšek, T.; Mayerhofer, M.; Schaart, D. R.; Lozano, I. Valencia; Parodi, K.

    2017-11-01

    A Compton camera-based detector system for photon detection from nuclear reactions induced by proton (or heavier ion) beams is under development at LMU Munich, targeting the online range verification of the particle beam in hadron therapy via prompt-gamma imaging. The detector is designed to be capable to reconstruct the photon source origin not only from the Compton scattering kinematics of the primary photon, but also to allow for tracking of the secondary Compton-scattered electrons, thus enabling a γ-source reconstruction also from incompletely absorbed photon events. The Compton camera consists of a monolithic LaBr3:Ce scintillation crystal, read out by a multi-anode PMT acting as absorber, preceded by a stacked array of 6 double-sided silicon strip detectors as scatterers. The detector components have been characterized both under offline and online conditions. The LaBr3:Ce crystal exhibits an excellent time and energy resolution. Using intense collimated 137Cs and 60Co sources, the monolithic scintillator was scanned on a fine 2D grid to generate a reference library of light amplitude distributions that allows for reconstructing the photon interaction position using a k-Nearest Neighbour (k-NN) algorithm. Systematic studies were performed to investigate the performance of the reconstruction algorithm, revealing an improvement of the spatial resolution with increasing photon energy to an optimum value of 3.7(1)mm at 1.33 MeV, achieved with the Categorical Average Pattern (CAP) modification of the k-NN algorithm.

  6. The Compton-Schwarzschild correspondence from extended de Broglie relations

    Energy Technology Data Exchange (ETDEWEB)

    Lake, Matthew J. [The Institute for Fundamental Study, “The Tah Poe Academia Institute' ,Naresuan University, Phitsanulok 65000 (Thailand); Thailand Center of Excellence in Physics, Ministry of Education,Bangkok 10400 (Thailand); Carr, Bernard [School of Physics and Astronomy, Queen Mary University of London,Mile End Road, London E1 4NS (United Kingdom)

    2015-11-17

    The Compton wavelength gives the minimum radius within which the mass of a particle may be localized due to quantum effects, while the Schwarzschild radius gives the maximum radius within which the mass of a black hole may be localized due to classial gravity. In a mass-radius diagram, the two lines intersect near the Planck point (l{sub P},m{sub P}), where quantum gravity effects become significant. Since canonical (non-gravitational) quantum mechanics is based on the concept of wave-particle duality, encapsulated in the de Broglie relations, these relations should break down near (l{sub P},m{sub P}). It is unclear what physical interpretation can be given to quantum particles with energy E≫m{sub P}c{sup 2}, since they correspond to wavelengths λ≪l{sub P} or time periods τ≪t{sub P} in the standard theory. We therefore propose a correction to the standard de Broglie relations, which gives rise to a modified Schrödinger equation and a modified expression for the Compton wavelength, which may be extended into the region E≫m{sub P}c{sup 2}. For the proposed modification, we recover the expression for the Schwarzschild radius for E≫m{sub P}c{sup 2} and the usual Compton formula for E≪m{sub P}c{sup 2}. The sign of the inequality obtained from the uncertainty principle reverses at m≈m{sub P}, so that the Compton wavelength and event horizon size may be interpreted as minimum and maximum radii, respectively. We interpret the additional terms in the modified de Broglie relations as representing the self-gravitation of the wave packet.

  7. On the line-shape analysis of Compton profiles and its application to neutron scattering

    International Nuclear Information System (INIS)

    Romanelli, G.; Krzystyniak, M.

    2016-01-01

    Analytical properties of Compton profiles are used in order to simplify the analysis of neutron Compton scattering experiments. In particular, the possibility to fit the difference of Compton profiles is discussed as a way to greatly decrease the level of complexity of the data treatment, making the analysis easier, faster and more robust. In the context of the novel method proposed, two mathematical models describing the shapes of differenced Compton profiles are discussed: the simple Gaussian approximation for harmonic and isotropic local potential, and an analytical Gauss–Hermite expansion for an anharmonic or anisotropic potential. The method is applied to data collected by VESUVIO spectrometer at ISIS neutron and muon pulsed source (UK) on Copper and Aluminium samples at ambient and low temperatures. - Highlights: • A new method to analyse neutron Compton scattering data is presented. • The method allows many corrections on the experimental data to be avoided. • The number of needed fitting parameters is drastically reduced using the new method. • Mass-selective analysis is facilitated with parametric studies benefiting the most. • Observables linked to anisotropic momentum distribution are obtained analytically.

  8. Technical Note: Influence of Compton currents on profile measurements in small-volume ion chambers

    Energy Technology Data Exchange (ETDEWEB)

    Tanny, Sean; Sperling, Nicholas; Parsai, E. Ishmael, E-mail: e.parsai@utoledo.edu [Department of Radiation Oncology, University of Toledo Medical Center, 1325 Conference Drive, Toledo, Ohio 43614 (United States); Holmes, Shannon [Standard Imaging, 3120 Deming Way, Middleton, Wisconsin 53562 (United States)

    2015-10-15

    Purpose: This work is to evaluate the effects of Compton current generation in three small-volume ionization chambers on measured beam characteristics for electron fields. Methods: Beam scans were performed using Exradin A16, A26, and PTW 31014 microchambers. Scans with varying chamber components shielded were performed. Static point measurements, output factors, and cable only irradiations were performed to determine the contribution of Compton currents to various components of the chamber. Monte Carlo simulations were performed to evaluate why one microchamber showed a significant reduction in Compton current generation. Results: Beam profiles demonstrated significant distortion for two of the three chambers when scanned parallel to the chamber axis, produced by electron deposition within the wire. Measurements of ionization produced within the cable identified Compton current generation as the cause of these distortions. The size of the central collecting wire was found to have the greatest influence on the magnitude of Compton current generation. Conclusions: Microchambers can demonstrate significant (>5%) deviations from properties as measured with larger volume chambers (0.125 cm{sup 3} and above). These deviations can be substantially reduced by averaging measurements conducted at opposite polarities.

  9. Soliton Compton Mass from Auto-Parametric Wave-Soliton Coupling

    CERN Document Server

    Binder, B

    2002-01-01

    In this paper a self-excited Rayleigh-type system models the auto-parametric wave-soliton coupling via phase fluctuations. The parameter of dissipative terms determine not only the most likely quantum coupling between solitons and linear waves but also the most likely mass of the solitons. Phase fluctuations are mediated by virtual photons coupling at light-velocity in a permanent Compton scattering process. With a reference to the SI-units and proper scaling relations in length and velocity, the final result shows a highly interesting sequence: the likely soliton Compton mass is about 1.00138 times the neutron and 1.00276 times the proton mass.

  10. Simplified slow anti-coincidence circuit for Compton suppression systems

    International Nuclear Information System (INIS)

    Al-Azmi, Darwish

    2008-01-01

    Slow coincidence circuits for the anti-coincidence measurements have been considered for use in Compton suppression technique. The simplified version of the slow circuit has been found to be fast enough, satisfactory and allows an easy system setup, particularly with the advantage of the automatic threshold setting of the low-level discrimination. A well-type NaI detector as the main detector surrounded by plastic guard detector has been arranged to investigate the performance of the Compton suppression spectrometer using the simplified slow circuit. The system has been tested to observe the improvement in the energy spectra for medium to high-energy gamma-ray photons from terrestrial and environmental samples

  11. Silicon photomultipliers as readout elements for a Compton effect polarimeter: the COMPASS project

    CERN Document Server

    Del Monte, E; Brandonisio, A; Muleri, F; Soffitta, P; Costa, E; di Persio, G; Cosimo, S Di; Massaro, E; Morbidini, A; Morelli, E; Pacciani, L; Fabiani, S; Michilli, D; Giarrusso, S; Catalano, O; Impiombato, D; Mineo, T; Sottile, G; Billotta, S

    2016-01-01

    COMpton Polarimeter with Avalanche Silicon readout (COMPASS) is a research and development project that aims to measure the polarization of X-ray photons through Compton Scattering. The measurement is obtained by using a set of small rods of fast scintillation materials with both low-Z (as active scatterer) and high-Z (as absorber), all read-out with Silicon Photomultipliers. By this method we can operate scattering and absorbing elements in coincidence, in order to reduce the background. In the laboratory we are characterising the SiPMs using different types of scintillators and we are optimising the performances in terms of energy resolution, energy threshold and photon tagging efficiency. We aim to study the design of two types of satellite-borne instruments: a focal plane polarimeter to be coupled with multilayer optics for hard X-rays and a large area and wide field of view polarimeter for transients and Gamma Ray Bursts. In this paper we describe the status of the COMPASS project, we report about the la...

  12. Non-Proportionality of Electron Response and Energy Resolution of Compton Electrons in Scintillators

    Science.gov (United States)

    Swiderski, L.; Marcinkowski, R.; Szawlowski, M.; Moszynski, M.; Czarnacki, W.; Syntfeld-Kazuch, A.; Szczesniak, T.; Pausch, G.; Plettner, C.; Roemer, K.

    2012-02-01

    Non-proportionality of light yield and energy resolution of Compton electrons in three scintillators (LaBr3:Ce, LYSO:Ce and CsI:Tl) were studied in a wide energy range from 10 keV up to 1 MeV. The experimental setup was comprised of a High Purity Germanium detector and tested scintillators coupled to a photomultiplier. Probing the non-proportionality and energy resolution curves at different energies was obtained by changing the position of various radioactive sources with respect to both detectors. The distance between both detectors and source was kept small to make use of Wide Angle Compton Coincidence (WACC) technique, which allowed us to scan large range of scattering angles simultaneously and obtain relatively high coincidence rate of 100 cps using weak sources of about 10 μCi activity. The results are compared with those obtained by direct irradiation of the tested scintillators with gamma-ray sources and fitting the full-energy peaks.

  13. Evaluation of Position Resolution for a Prototype Whole-Body PET Detector Based on Suppressing Backgrounds by Compton Scattering

    Science.gov (United States)

    Fujihara, Kento; Emoto, Yusaku; Ito, Hiroshi; Kaneko, Naomi; Kaneko, Hideyuki; Kawai, Hideyuki; Kobayashi, Atsushi; Mizuno, Takahiro

    2018-01-01

    Existing PET (Positron Emission Tomography) systems make clear images in demonstration (measuring small PET reagent in pure water), however images in real diagnosis become unclear. The authors suspected that this problem was caused by Compton scattering in a detector. When PET systems observe plural photomultiplier tube outputs, an original emission point is regarded as centroid of the outputs. However, even if plural emission in Compton scattering occur, these systems calculate original point in the same way as single emission. Therefore, the authors considered that rejecting Compton scattering events makes PET systems much better, and made prototype counter. Main components of the prototype counter are plate-like high-growth-rate (HGR) La-GPS scintillators and wavelength shifting fibers (WLSF). HGR crystals grow 10 times as fast as a mono-crystal (a normal mono-crystal grows at 2 - 3 mm an hour). Thus, it includes microbubble and its transparency get worth. Consequently, HGR crystals usually are not used in radiation measuring instruments. However, this time they are used on the purpose. Because of their low transparency, scintillation lights come out right above and right under of emission position. Therefore, Compton scattering events is rejected easily. The prototype detector has an effective area of 300 by 300 square mm. The detector consists of 24 layers. One layer consists of HGR La-GPS scintillator of 1 mm thickness. Top and bottom surface of scintillator were covered by dual sheets of WLSF with a diameter of 0.2 mm. Sheets of WLSF on top and bottom of the scintillator make a right angle with each other, and measure X- and Y-components. Z-component is measured by difference of WLSF outputs between top and bottom. If plural layers output signals, this counter regards the event as Compton scattering event, and reject the event. Even if only a layer output signals, the event is rejected when number output signals from WLSF is more than 1.5 times of single

  14. Gamma-spectrometry with Compton suppressed detectors arrays

    International Nuclear Information System (INIS)

    Schueck, C.; Hannachi, F.; Chapman, R.

    1985-01-01

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

  15. Analytical description of photon beam phase spaces in inverse Compton scattering sources

    Directory of Open Access Journals (Sweden)

    C. Curatolo

    2017-08-01

    Full Text Available We revisit the description of inverse Compton scattering sources and the photon beams generated therein, emphasizing the behavior of their phase space density distributions and how they depend upon those of the two colliding beams of electrons and photons. The main objective is to provide practical formulas for bandwidth, spectral density, brilliance, which are valid in general for any value of the recoil factor, i.e. both in the Thomson regime of negligible electron recoil, and in the deep Compton recoil dominated region, which is of interest for gamma-gamma colliders and Compton sources for the production of multi-GeV photon beams. We adopt a description based on the center of mass reference system of the electron-photon collision, in order to underline the role of the electron recoil and how it controls the relativistic Doppler/boost effect in various regimes. Using the center of mass reference frame greatly simplifies the treatment, allowing us to derive simple formulas expressed in terms of rms momenta of the two colliding beams (emittance, energy spread, etc. and the collimation angle in the laboratory system. Comparisons with Monte Carlo simulations of inverse Compton scattering in various scenarios are presented, showing very good agreement with the analytical formulas: in particular we find that the bandwidth dependence on the electron beam emittance, of paramount importance in Thomson regime, as it limits the amount of focusing imparted to the electron beam, becomes much less sensitive in deep Compton regime, allowing a stronger focusing of the electron beam to enhance luminosity without loss of mono-chromaticity. A similar effect occurs concerning the bandwidth dependence on the frequency spread of the incident photons: in deep recoil regime the bandwidth comes out to be much less dependent on the frequency spread. The set of formulas here derived are very helpful in designing inverse Compton sources in diverse regimes, giving a

  16. Compton profile with synchrotron light - application to Y-123 superconductivity

    International Nuclear Information System (INIS)

    De, Udayan

    2005-01-01

    Electron beam accelerated to 6 GeV in the European Synchrotron Radiation Facility (ESRF) at Grenoble, France, can deliver highly mono-energetic, intense (10 12 photons/sec at sample at 100 mA ring current) and fine photon beam reaching x-ray and γ energies. So photons of 57 keV from this synchrotron has been used for Compton Profile or CP experiment (at different temperatures down to 70 K) on our YBa 2 Cu 3 O 7 or Y-123 single crystals with T c = 91 K. Photons, Compton scattered even at a definite angle, θ, show a distribution (called Compton Profile) of energy and hence of momentum reflecting the EMD or electron momentum distribution in the solid. The temperature variation of S-parameter, defined as the fraction of low momentum electrons, has been found from preliminary CP data. It confirmed the surprising double minimum found from Doppler broadening of positron annihilation radiation lineshape (DBPARL). The CP set-up at the synchrotron including the detectors and cryogenics as well as the new results are outlined. (author)

  17. ILC beam energy measurement by means of laser Compton backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Muchnoi, N. [Budker Inst. for Nuclear Physics, Novosibirsk (Russian Federation); Schreiber, H.J.; Viti, M. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany)

    2008-10-15

    A novel, non-invasive method of measuring the beam energy at the International Linear Collider is proposed. Laser light collides head-on with beam particles and either the energy of the Compton scattered electrons near the kinematic end-point is measured or the positions of the Compton backscattered {gamma}-rays, the edge electrons and the unscattered beam particles are recorded. A compact layout for the Compton spectrometer is suggested. It consists of a bending magnet and position sensitive detectors operating in a large radiation environment. Several options for high spatial resolution detectors are discussed. Simulation studies support the use of an infrared or green laser and quartz fiber detectors to monitor the backscattered photons and edge electrons. Employing a cavity monitor, the beam particle position downstream of the magnet can be recorded with submicrometer precision. Such a scheme provides a feasible and promising method to access the incident beam energy with precisions of 10{sup -4} or better on a bunch-to-bunch basis while the electron and positron beams are in collision. (orig.)

  18. ILC beam energy measurement by means of laser Compton backscattering

    International Nuclear Information System (INIS)

    Muchnoi, N.; Schreiber, H.J.; Viti, M.

    2008-10-01

    A novel, non-invasive method of measuring the beam energy at the International Linear Collider is proposed. Laser light collides head-on with beam particles and either the energy of the Compton scattered electrons near the kinematic end-point is measured or the positions of the Compton backscattered γ-rays, the edge electrons and the unscattered beam particles are recorded. A compact layout for the Compton spectrometer is suggested. It consists of a bending magnet and position sensitive detectors operating in a large radiation environment. Several options for high spatial resolution detectors are discussed. Simulation studies support the use of an infrared or green laser and quartz fiber detectors to monitor the backscattered photons and edge electrons. Employing a cavity monitor, the beam particle position downstream of the magnet can be recorded with submicrometer precision. Such a scheme provides a feasible and promising method to access the incident beam energy with precisions of 10 -4 or better on a bunch-to-bunch basis while the electron and positron beams are in collision. (orig.)

  19. Electronic structure of the palladium hydride studied by compton scattering

    CERN Document Server

    Mizusaki, S; Yamaguchi, M; Hiraoka, N; Itou, M; Sakurai, Y

    2003-01-01

    The hydrogen-induced changes in the electronic structure of Pd have been investigated by Compton scattering experiments associated with theoretical calculations. Compton profiles (CPs) of single crystal of Pd and beta phase hydride PdH sub x (x=0.62-0.74) have been measured along the [100], [110] and [111] directions with a momentum resolution of 0.14-0.17 atomic units using 115 keV x-rays. The theoretical Compton profiles have been calculated from the wavefunctions obtained utilizing the full potential linearized augmented plane wave method within the local density approximation for Pd and stoichiometric PdH. The experimental and the theoretical results agreed well with respect to the difference in the CPs between PdH sub x and Pd, and the anisotropy in the CPs of Pd or PdH sub x. This study provides lines of evidence that upon hydride formation the lowest valance band of Pd is largely modified due to hybridization with H 1s-orbitals and the Fermi energy is raised into the sp-band. (author)

  20. Compton scattering at finite temperature: thermal field dynamics approach

    International Nuclear Information System (INIS)

    Juraev, F.I.

    2006-01-01

    Full text: Compton scattering is a classical problem of quantum electrodynamics and has been studied in its early beginnings. Perturbation theory and Feynman diagram technique enables comprehensive analysis of this problem on the basis of which famous Klein-Nishina formula is obtained [1, 2]. In this work this problem is extended to the case of finite temperature. Finite-temperature effects in Compton scattering is of practical importance for various processes in relativistic thermal plasmas in astrophysics. Recently Compton effect have been explored using closed-time path formalism with temperature corrections estimated [3]. It was found that the thermal cross section can be larger than that for zero-temperature by several orders of magnitude for the high temperature realistic in astrophysics [3]. In our work we use a main tool to account finite-temperature effects, a real-time finite-temperature quantum field theory, so-called thermofield dynamics [4, 5]. Thermofield dynamics is a canonical formalism to explore field-theoretical processes at finite temperature. It consists of two steps, doubling of Fock space and Bogolyubov transformations. Doubling leads to appearing additional degrees of freedom, called tilded operators which together with usual field operators create so-called thermal doublet. Bogolyubov transformations make field operators temperature-dependent. Using this formalism we treat Compton scattering at finite temperature via replacing in transition amplitude zero-temperature propagators by finite-temperature ones. As a result finite-temperature extension of the Klein-Nishina formula is obtained in which differential cross section is represented as a sum of zero-temperature cross section and finite-temperature correction. The obtained result could be useful in quantum electrodynamics of lasers and for relativistic thermal plasma processes in astrophysics where correct account of finite-temperature effects is important. (author)

  1. Virtual Compton Scattering off a Spinless Target in the AdS/QCD correspondence

    CERN Document Server

    Marquet, C.; Wallon, S.

    2010-01-01

    We perform a study of the doubly virtual Compton scattering off a spinless target gamma* P -> gamma* P' within the Anti-de Sitter(AdS)/QCD formalism. We find that the general structure allowed by the Lorentz invariance and gauge invariance of the Compton amplitude is not easily reproduced with the standard recipes of the AdS/QCD correspondence. In the soft-photon regime, where the semi-classical approximation is supposed to apply best, we show that the measurements of the electric and magnetic polarizabilities of a target like the charged pion in real Compton scattering, can already serve as stringent tests, and presumably exclude results based on the AdS/QCD correspondence in its minimal version.

  2. Resonant Inverse Compton Scattering Spectra from Highly Magnetized Neutron Stars

    Science.gov (United States)

    Wadiasingh, Zorawar; Baring, Matthew G.; Gonthier, Peter L.; Harding, Alice K.

    2018-02-01

    Hard, nonthermal, persistent pulsed X-ray emission extending between 10 and ∼150 keV has been observed in nearly 10 magnetars. For inner-magnetospheric models of such emission, resonant inverse Compton scattering of soft thermal photons by ultrarelativistic charges is the most efficient production mechanism. We present angle-dependent upscattering spectra and pulsed intensity maps for uncooled, relativistic electrons injected in inner regions of magnetar magnetospheres, calculated using collisional integrals over field loops. Our computations employ a new formulation of the QED Compton scattering cross section in strong magnetic fields that is physically correct for treating important spin-dependent effects in the cyclotron resonance, thereby producing correct photon spectra. The spectral cutoff energies are sensitive to the choices of observer viewing geometry, electron Lorentz factor, and scattering kinematics. We find that electrons with energies ≲15 MeV will emit most of their radiation below 250 keV, consistent with inferred turnovers for magnetar hard X-ray tails. More energetic electrons still emit mostly below 1 MeV, except for viewing perspectives sampling field-line tangents. Pulse profiles may be singly or doubly peaked dependent on viewing geometry, emission locale, and observed energy band. Magnetic pair production and photon splitting will attenuate spectra to hard X-ray energies, suppressing signals in the Fermi-LAT band. The resonant Compton spectra are strongly polarized, suggesting that hard X-ray polarimetry instruments such as X-Calibur, or a future Compton telescope, can prove central to constraining model geometry and physics.

  3. Compton Reflection in AGN with Simbol-X

    Science.gov (United States)

    Beckmann, V.; Courvoisier, T. J.-L.; Gehrels, N.; Lubiński, P.; Malzac, J.; Petrucci, P. O.; Shrader, C. R.; Soldi, S.

    2009-05-01

    AGN exhibit complex hard X-ray spectra. Our current understanding is that the emission is dominated by inverse Compton processes which take place in the corona above the accretion disk, and that absorption and reflection in a distant absorber play a major role. These processes can be directly observed through the shape of the continuum, the Compton reflection hump around 30 keV, and the iron fluorescence line at 6.4 keV. We demonstrate the capabilities of Simbol-X to constrain complex models for cases like MCG-05-23-016, NGC 4151, NGC 2110, and NGC 4051 in short (10 ksec) observations. We compare the simulations with recent observations on these sources by INTEGRAL, Swift and Suzaku. Constraining reflection models for AGN with Simbol-X will help us to get a clear view of the processes and geometry near to the central engine in AGN, and will give insight to which sources are responsible for the Cosmic X-ray background at energies >20 keV.

  4. Comparative Compton scattering studies in Cu2O and Ag2O

    International Nuclear Information System (INIS)

    Bandyopadhyay, S.; Chatterjee, A.K.; Saha, S.K.; Chatterjee, A.

    1994-01-01

    Compton scattering studies in polycrystalline Cu 2 O and Ag 2 O with 59.54 keV γ radiation are reported. A comparison has been made between the valance Compton profiles of these two components scaled to lattice momentum by normalizing them to equal electron density for outer valence electrons, and this comparison shows some differences between the bonding characters of Cu 2 O and Ag 2 O. (author)

  5. Progress towards a semiconductor Compton camera for prompt gamma imaging during proton beam therapy for range and dose verification

    Science.gov (United States)

    Gutierrez, A.; Baker, C.; Boston, H.; Chung, S.; Judson, D. S.; Kacperek, A.; Le Crom, B.; Moss, R.; Royle, G.; Speller, R.; Boston, A. J.

    2018-01-01

    The main objective of this work is to test a new semiconductor Compton camera for prompt gamma imaging. Our device is composed of three active layers: a Si(Li) detector as a scatterer and two high purity Germanium detectors as absorbers of high-energy gamma rays. We performed Monte Carlo simulations using the Geant4 toolkit to characterise the expected gamma field during proton beam therapy and have made experimental measurements of the gamma spectrum with a 60 MeV passive scattering beam irradiating a phantom. In this proceeding, we describe the status of the Compton camera and present the first preliminary measurements with radioactive sources and their corresponding reconstructed images.

  6. Compton Gamma-Ray Observatory

    Science.gov (United States)

    1991-01-01

    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.

  7. Model independent dispersion approach to proton Compton scattering

    International Nuclear Information System (INIS)

    Caprini, I.; Radescu, E.E.

    1980-12-01

    The proton Compton scattering at low and intermediate energies is studied by means of a dispersion framework which exploits in an optimal way the (fixed momentum transfer) analyticity properties of the amplitudes in conjunction with the consequences of the (s-channel) unitarity. The mathematical background of the work consists of methods specific to boundary value problems for analytic vector-valued functions and interpolation theory. In comparison with previous related work, the external problems to be solved now are much more difficult because of the inclusion of the photoproduction input and also lead to additional computational complications. The lower bounds on the differential cross-section, obtained without any reference to subtractions and annihilation channel contributions, appear sufficiently restrictive to evidentiate rigorously some inconsistencies between results of single pion photoproduction multipole extractions and proton Compton scattering data. (author)

  8. Compton's Kinematics and Einstein - Ehrenfest's radiation theory

    International Nuclear Information System (INIS)

    Barranco, A.V.; Franca, H.M.

    1988-09-01

    The Compton Kinematic relations are obtained from entirely classical arguments, that is, without the corpuscular concept of the photon. The calculations are nonrelativistic and result from Einstein and Ehrenfest's radiation theory modified in order to introduce the effects of the classical zero-point fileds characteristic of Stochastic Electrodynamics. (author) [pt

  9. X-ray generator based on Compton scattering

    NARCIS (Netherlands)

    Androsov, V.P.; Agafonov, A.V.; Botman, J.I.M.; Bulyak, E.V.; Drebot, I.; Gladkikh, P.I.; Grevtsev, V.; Ivashchenko, V.; Karnaukhov, I.M.; Lapshin, V.I.

    2005-01-01

    Nowadays, the sources of the X-rays based on a storage ring with low beam energy and Compton scattering of intense laser beam are under development in several laboratories. In the paper the state-of-art in development and construction of cooperative project of a Kharkov advanced X-ray source NESTOR

  10. Electronic structure of hafnium: A Compton profile study

    Indian Academy of Sciences (India)

    To extract the true Compton profile from the raw data, the raw data were cor- rected for ... For the present sample and experimental conditions, the contribution of .... are in better agreement with the simple renormalized free atom calculations for.

  11. Correlation between proliferative activity and cellular thickness of human mesenchymal stem cells

    International Nuclear Information System (INIS)

    Katsube, Yoshihiro; Hirose, Motohiro; Nakamura, Chikashi; Ohgushi, Hajime

    2008-01-01

    A cell's shape is known to be related to its proliferative activity. In particular, large and flat mammalian adult stem cells seem to show slow proliferation, however using quantitative analysis to prove the phenomenon is difficult. We measured the proliferation and cellular thickness of human mesenchymal stem cells (MSCs) by atomic force microscopy and found that MSCs with high proliferative activity were thick while those with low proliferative activity were thin, even though these MSCs were early passage cells. Further, low proliferative MSCs contained many senescence-associated β-galactosidase positive cells together with high senescence-associated gene expression. These findings suggest that the measurement of cellular thickness is useful for estimating the proliferative activity of human MSCs and is expected to be a practical tool for MSC applications in regenerative medicine

  12. Deeply virtual compton scattering on a virtual pion target

    International Nuclear Information System (INIS)

    Amrath, D.; Diehl, M.; Lansberg, J.P.; Heidelberg Univ.

    2008-07-01

    We study deeply virtual Compton scattering on a virtual pion that is emitted by a proton. Using a range of models for the generalized parton distributions of the pion, we evaluate the cross section, as well as the beam spin and beam charge asymmetries in the leading-twist approximation. Studying Compton scattering on the pion in suitable kinematics puts high demands on both beam energy and luminosity, and we find that the corresponding requirements will first be met after the energy upgrade at Jefferson Laboratory. As a by-product of our study, we construct a parameterization of pion generalized parton distributions that has a non-trivial interplay between the x and t dependence and is in good agreement with form factor data and lattice calculations. (orig.)

  13. Study of electron densities of normal and neoplastic human breast tissues by Compton scattering using synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Antoniassi, M.; Conceicao, A.L.C. [Departamento de Fisica-Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil); Poletti, M.E., E-mail: poletti@ffclrp.usp.br [Departamento de Fisica-Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto-Universidade de Sao Paulo, Ribeirao Preto, Sao Paulo (Brazil)

    2012-07-15

    Electron densities of 33 samples of normal (adipose and fibroglangular) and neoplastic (benign and malignant) human breast tissues were determined through Compton scattering data using a monochromatic synchrotron radiation source and an energy dispersive detector. The area of Compton peaks was used to determine the electron densities of the samples. Adipose tissue exhibits the lowest values of electron density whereas malignant tissue the highest. The relationship with their histology was discussed. Comparison with previous results showed differences smaller than 4%. - Highlights: Black-Right-Pointing-Pointer Electron density of normal and neoplastic breast tissues was measured using Compton scattering. Black-Right-Pointing-Pointer Monochromatic synchrotron radiation was used to obtain the Compton scattering data. Black-Right-Pointing-Pointer The area of Compton peaks was used to determine the electron densities of samples. Black-Right-Pointing-Pointer Adipose tissue shows the lowest electron density values whereas the malignant tissue the highest. Black-Right-Pointing-Pointer Comparison with previous results showed differences smaller than 4%.

  14. Study of electron densities of normal and neoplastic human breast tissues by Compton scattering using synchrotron radiation

    International Nuclear Information System (INIS)

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

    2012-01-01

    Electron densities of 33 samples of normal (adipose and fibroglangular) and neoplastic (benign and malignant) human breast tissues were determined through Compton scattering data using a monochromatic synchrotron radiation source and an energy dispersive detector. The area of Compton peaks was used to determine the electron densities of the samples. Adipose tissue exhibits the lowest values of electron density whereas malignant tissue the highest. The relationship with their histology was discussed. Comparison with previous results showed differences smaller than 4%. - Highlights: ► Electron density of normal and neoplastic breast tissues was measured using Compton scattering. ► Monochromatic synchrotron radiation was used to obtain the Compton scattering data. ► The area of Compton peaks was used to determine the electron densities of samples. ► Adipose tissue shows the lowest electron density values whereas the malignant tissue the highest. ► Comparison with previous results showed differences smaller than 4%.

  15. Experimental and theoretical Compton profiles of Be, C and Al

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Julio C., E-mail: jaguiar@arn.gob.a [Autoridad Regulatoria Nuclear, Av. Del Libertador 8250, C1429BNP, Buenos Aires (Argentina); Instituto de Fisica ' Arroyo Seco' , Facultad de Ciencias Exactas, U.N.C.P.B.A., Pinto 399, 7000 Tandil (Argentina); Di Rocco, Hector O. [Instituto de Fisica ' Arroyo Seco' , Facultad de Ciencias Exactas, U.N.C.P.B.A., Pinto 399, 7000 Tandil (Argentina); Arazi, Andres [Laboratorio TANDAR, Comision Nacional de Energia Atomica, Av. General Paz 1499, 1650 San Martin, Buenos Aires (Argentina)

    2011-02-01

    The results of Compton profile measurements, Fermi momentum determinations, and theoretical values obtained from a linear combination of Slater-type orbital (STO) for core electrons in beryllium; carbon and aluminium are presented. In addition, a Thomas-Fermi model is used to estimate the contribution of valence electrons to the Compton profile. Measurements were performed using monoenergetic photons of 59.54 keV provided by a low-intensity Am-241 {gamma}-ray source. Scattered photons were detected at 90{sup o} from the beam direction using a p-type coaxial high-purity germanium detector (HPGe). The experimental results are in good agreement with theoretical calculations.

  16. Electron momentum density measurements by means of positron annihilation and Compton spectroscopy

    International Nuclear Information System (INIS)

    Gerber, W.; Dlubek, G.; Marx, U.; Bruemmer, O.; Prautzsch, J.

    1982-01-01

    The electron momentum density is measured applying positron annihilation and Compton spectroscopy in order to get information about electron wave functions. Compton spectroscopic measurements of Pd-Ag and Cu-Zn alloy systems are carried out taking into account crystal structure, mixability, and order state. Three-dimensional momentum densities of silicon are determined in order to get better information about its electronic structure. The momentum density and the spin density of ferromagnetic nickel are investigated using angular correlation curves

  17. A quartz Cherenkov detector for Compton-polarimetry at future e+e- colliders

    International Nuclear Information System (INIS)

    List, Jenny; Vauth, Annika; Vormwald, Benedikt; Hamburg Univ.

    2015-02-01

    Precision polarimetry is essential for future e + e - colliders and requires Compton polarimeters designed for negligible statistical uncertainties. In this paper, we discuss the design and construction of a quartz Cherenkov detector for such Compton polarimeters. The detector concept has been developed with regard to the main systematic uncertainties of the polarisation measurements, namely the linearity of the detector response and detector alignment. Simulation studies presented here imply that the light yield reachable by using quartz as Cherenkov medium allows to resolve in the Cherenkov photon spectra individual peaks corresponding to different numbers of Compton electrons. The benefits of the application of a detector with such single-peak resolution to the polarisation measurement are shown for the example of the upstream polarimeters foreseen at the International Linear Collider. Results of a first testbeam campaign with a four-channel prototype confirming simulation predictions for single electrons are presented.

  18. On the possibility of using X-ray Compton scattering to study magnetoelectrical properties of crystals

    Energy Technology Data Exchange (ETDEWEB)

    Collins, S. P., E-mail: steve.collins@diamond.ac.uk; Laundy, D.; Connolley, T.; Laan, G. van der; Fabrizi, F. [Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot, OX11 0DE (United Kingdom); Janssen, O. [Department of Physics, New York University, New York, NY 10003 (United States); Cooper, M. J. [Department of Physics, University of Warwick, CV4 7AL (United Kingdom); Ebert, H.; Mankovsky, S. [Universität München, Department Chemie, Haus E2.033, Butenandtstrasse 5-13, D-81377 München (Germany)

    2016-02-16

    The possibility of using X-ray Compton scattering to reveal antisymmetric components of the electron momentum density, as a fingerprint of magnetoelectric sample properties, is investigated experimentally and theoretically by studying the polar ferromagnet GaFeO{sub 3}. This paper discusses the possibility of using Compton scattering – an inelastic X-ray scattering process that yields a projection of the electron momentum density – to probe magnetoelectrical properties. It is shown that an antisymmetric component of the momentum density is a unique fingerprint of such time- and parity-odd physics. It is argued that polar ferromagnets are ideal candidates to demonstrate this phenomenon and the first experimental results are shown, on a single-domain crystal of GaFeO{sub 3}. The measured antisymmetric Compton profile is very small (≃ 10{sup −5} of the symmetric part) and of the same order of magnitude as the statistical errors. Relativistic first-principles simulations of the antisymmetric Compton profile are presented and it is shown that, while the effect is indeed predicted by theory, and scales with the size of the valence spin–orbit interaction, its magnitude is significantly overestimated. The paper outlines some important constraints on the properties of the antisymmetric Compton profile arising from the underlying crystallographic symmetry of the sample.

  19. A Compton scattering technique to determine wood density and locating defects in it

    International Nuclear Information System (INIS)

    Tondon, Akash; Sandhu, B. S.; Singh, Bhajan; Singh, Mohinder

    2015-01-01

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

  20. The electron beam dynamics simulation in the laser-electron storage ring involving compton and intrabeam scattering

    International Nuclear Information System (INIS)

    Gladkikh, P.I.; Telegin, Yu.N.; Karnaukhov, I.M.

    2002-01-01

    The feasibility of the development of intense X-ray sources based on Compton scattering in laser-electron storage rings is discussed. The results of the electron beam dynamics simulation involving Compton and intrabeam scattering are presented

  1. The electron beam dynamics simulation in the laser-electron storage ring involving compton and intrabeam scattering

    CERN Document Server

    Gladkikh, P I; Karnaukhov, I M

    2002-01-01

    The feasibility of the development of intense X-ray sources based on Compton scattering in laser-electron storage rings is discussed. The results of the electron beam dynamics simulation involving Compton and intrabeam scattering are presented.

  2. Verification of Compton scattering spectrum of a 662 keV photon beam scattered on a cylindrical steel target using MCNP5 code

    International Nuclear Information System (INIS)

    Thanh, Tran Thien; Nguyen, Vo Hoang; Chuong, Huynh Dinh; Tran, Le Bao; Tam, Hoang Duc; Binh, Nguyen Thi; Tao, Chau Van

    2015-01-01

    This article focuses on the possible application of a "1"3"7Cs low-radioactive source (5 mCi) and a NaI(Tl) detector for measuring the saturation thickness of solid cylindrical steel targets. In order to increase the reliability of the obtained experimental results and to verify the detector response function of Compton scattering spectrum, simulation using Monte Carlo N-particle (MCNP5) code is performed. The obtained results are in good agreement with the response functions of the simulation scattering and experimental scattering spectra. On the basis of such spectra, the saturation depth of a steel cylinder is determined by experiment and simulation at about 27 mm using gamma energy of 662 keV ("1"3"7Cs) at a scattering angle of 120°. This study aims at measuring the diameter of solid cylindrical objects by gamma-scattering technique. - Highlights: • This study aims a possible application a "1"3"7Cs low-radioactive source (5 mCi) and a NaI(Tl) detector for measuring the saturation thickness of solid cylindrical steel targets by gamma-scattering technique. • Monte Carlo N-particle (MCNP5) code is performed to verify on the detector response function of Compton scattering spectrum. • The results show a good agreement in response function of the experimental and simulation scattering spectra. • The saturation depth of a steel cylinder is determined by experiment and simulation at about 27 mm using gamma energy of 662 keV ("1"3"7Cs) at a scattering angle of 120°.

  3. Colour dipoles and virtual Compton scattering

    International Nuclear Information System (INIS)

    McDermott, M.

    2002-01-01

    An analysis of Deeply Virtual Compton Scattering (DVCS) is made within the colour dipole model. We compare and contrast two models for the dipole cross-section which have been successful in describing structure function data. Both models agree with the available cross section data on DVCS from HERA. We give predictions for various azimuthal angle asymmetries in HERA kinematics and for the DVCS cross section in the THERA region. (orig.)

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

    International Nuclear Information System (INIS)

    Rohe, R.C.; Valentine, J.D.

    1996-01-01

    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 (ΔE = E 0 - E SC , where E 0 , ΔE, and E 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

  5. Electronic properties and Compton profiles of silver iodide

    Indian Academy of Sciences (India)

    We have carried out an extensive study of electronic properties of silver iodide in - and -phases. The theoretical Compton profiles, energy bands, density of states and anisotropies in momentum densities are computed using density functional theories. We have also employed full-potential linearized augmented ...

  6. Constraints on low energy Compton scattering amplitudes

    International Nuclear Information System (INIS)

    Raszillier, I.

    1979-04-01

    We derive the constraints and correlations of fairly general type for Compton scattering amplitudes at energies below photoproduction threshold and fixed momentum transfer, following from (an upper bound on) the corresponding differential cross section above photoproduction threshold. The derivation involves the solution of an extremal problem in a certain space of vector - valued analytic functions. (author)

  7. Compton scattering and γ-quanta monochromatization

    International Nuclear Information System (INIS)

    Goryachev, B.I.; Shevchenko, V.G.

    1979-01-01

    The γ-quanta monochromatization method is proposed for sdudying high-excited states and mechanisms of nuclei photodisintegration. The method is based on the properties of photon Compton scattering. It permits to obtain high energy resolution without accurate analysis of the particle energies taking part in the scattering process. A possible design of the compton γ- monochromator is presented. The γ-quanta scatterer of the elements with a small nucleus charge (e.g. LiH) is placed inside the β-spectrometer of low resolution. The monochromator is expected to operate in the γ-beam of the high-current synchrotron, and it provides for a rather good energy resolution rho(W) while studying the high-excited nucleus states (rho(W) approximately 2% in the range of the giant dipole resonance). With the γ-quanta energy growth rho(W) increases as Wsup(0.6). The monochromator permits to obtain high statistical accuracy for a smaller period of time (at a considerably better energy resolution) than while working with a bremsstrahlung spectrum. The yield of quasimonochromatic photons related to the ΔW(ΔW = rho(W)W) range of energy resolution increases as Wsup(0.6). This fact makes it promjssing to use monochromator in the energy range considerably exceeding the characteristic energy of the gigantic dipole resonance

  8. Reconstruction of the electron momentum distribution from a set of directional Compton profiles

    International Nuclear Information System (INIS)

    Hansen, N.K.

    1980-12-01

    A method is described in which the 3-dimensional one-electron momentum density distribution is obtained from a series of directional Compton profiles measured on single crystals; a directional Compton profile being the projection of the momentum density onto a line through the origin. The procedure consists of 1-dimensional Fourier transformations of the individual profiles. The Fourier transformed Compton profiles are fitted by a finite expansion in lattice harmonic functions, and the momentum density is finally obtained by a 3-dimensional Fourier transform. The effect of statistical errors are derived both for the momentum density and its Fourier transform. The problem of how to carry out the measurements in an optimal way has been approached and suggestions made. A computer program for calculation of momentum density and error distributions have been listed in an appendix. (orig.)

  9. Optimization of Compton-suppression and summing schemes for the TIGRESS HPGe detector array

    Science.gov (United States)

    Schumaker, M. A.; Svensson, C. E.; Andreoiu, C.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Boston, A. J.; Chakrawarthy, R. S.; Churchman, R.; Drake, T. E.; Finlay, P.; Garrett, P. E.; Grinyer, G. F.; Hackman, G.; Hyland, B.; Jones, B.; Maharaj, R.; Morton, A. C.; Pearson, C. J.; Phillips, A. A.; Sarazin, F.; Scraggs, H. C.; Smith, M. B.; Valiente-Dobón, J. J.; Waddington, J. C.; Watters, L. M.

    2007-04-01

    Methods of optimizing the performance of an array of Compton-suppressed, segmented HPGe clover detectors have been developed which rely on the physical position sensitivity of both the HPGe crystals and the Compton-suppression shields. These relatively simple analysis procedures promise to improve the precision of experiments with the TRIUMF-ISAC Gamma-Ray Escape-Suppressed Spectrometer (TIGRESS). Suppression schemes will improve the efficiency and peak-to-total ratio of TIGRESS for high γ-ray multiplicity events by taking advantage of the 20-fold segmentation of the Compton-suppression shields, while the use of different summing schemes will improve results for a wide range of experimental conditions. The benefits of these methods are compared for many γ-ray energies and multiplicities using a GEANT4 simulation, and the optimal physical configuration of the TIGRESS array under each set of conditions is determined.

  10. Amino Acid Composition, Urease Activity and Trypsin Inhibitor Activity after Toasting of Soybean in Thick and Thin Layer

    OpenAIRE

    Krička, Tajana; Jurišić, Vanja; Voća, Neven; Ćurić, Duška; Brlek Savić, Tea; Matin, Ana

    2009-01-01

    The objective of this study was to determine amino acid content, urease activity and trypsin inhibitor activity in soybean grain for polygastric animals’ feed aft er toasting with the aim to introduce thick layer in toasting technology. Hence, soybean was toasted both in thick and thin layer at 130 oC during 10 minutes. In order to properly monitor the technological process of soybean thermal processing, it was necessary to study crude protein content, urease activity, trypsin inhibitor activ...

  11. High-Energy Compton Scattering Light Sources

    CERN Document Server

    Hartemann, Fred V; Barty, C; Crane, John; Gibson, David J; Hartouni, E P; Tremaine, Aaron M

    2005-01-01

    No monochromatic, high-brightness, tunable light sources currently exist above 100 keV. Important applications that would benefit from such new hard x-ray sources include: nuclear resonance fluorescence spectroscopy, time-resolved positron annihilation spectroscopy, and MeV flash radiography. The peak brightness of Compton scattering light sources is derived for head-on collisions and found to scale with the electron beam brightness and the drive laser pulse energy. This gamma 2

  12. Impact of measuring electron tracks in high-resolution scientific charge-coupled devices within Compton imaging systems

    International Nuclear Information System (INIS)

    Chivers, D.H.; Coffer, A.; Plimley, B.; Vetter, K.

    2011-01-01

    We have implemented benchmarked models to determine the gain in sensitivity of electron-tracking based Compton imaging relative to conventional Compton imaging by the use of high-resolution scientific charge-coupled devices (CCD). These models are based on the recently demonstrated ability of electron-tracking based Compton imaging by using fully depleted scientific CCDs. Here we evaluate the gain in sensitivity by employing Monte Carlo simulations in combination with advanced charge transport models to calculate two-dimensional charge distributions corresponding to experimentally obtained tracks. In order to reconstruct the angle of the incident γ-ray, a trajectory determination algorithm was used on each track and integrated into a back-projection routine utilizing a geodesic-vertex ray tracing technique. Analysis was performed for incident γ-ray energies of 662 keV and results show an increase in sensitivity consistent with tracking of the Compton electron to approximately ±30 o .

  13. Attenuation studies near K-absorption edges using Compton ...

    Indian Academy of Sciences (India)

    The results are consistent with theoretical values derived from the XCOM package. Keywords. Photon interaction; 241Am; gamma ray attenuation; Compton scattering; absorption edge; rare earth elements. PACS Nos 32.80.-t; 32.90.+a. 1. Introduction. Photon interaction studies at energies around the absorption edge have ...

  14. Theorems of low energy in Compton scattering

    International Nuclear Information System (INIS)

    Chahine, J.

    1984-01-01

    We have obtained the low energy theorems in Compton scattering to third and fouth order in the frequency of the incident photon. Next we calculated the polarized cross section to third order and the unpolarized to fourth order in terms of partial amplitudes not covered by the low energy theorems, what will permit the experimental determination of these partial amplitudes. (Author) [pt

  15. Three-dimensional imaging of flat natural and cultural heritage objects by a Compton scattering modality

    Science.gov (United States)

    Guerrero Prado, Patricio; Nguyen, Mai K.; Dumas, Laurent; Cohen, Serge X.

    2017-01-01

    Characterization and interpretation of flat ancient material objects, such as those found in archaeology, paleoenvironments, paleontology, and cultural heritage, have remained a challenging task to perform by means of conventional x-ray tomography methods due to their anisotropic morphology and flattened geometry. To overcome the limitations of the mentioned methodologies for such samples, an imaging modality based on Compton scattering is proposed in this work. Classical x-ray tomography treats Compton scattering data as noise in the image formation process, while in Compton scattering tomography the conditions are set such that Compton data become the principal image contrasting agent. Under these conditions, we are able, first, to avoid relative rotations between the sample and the imaging setup, and second, to obtain three-dimensional data even when the object is supported by a dense material by exploiting backscattered photons. Mathematically this problem is addressed by means of a conical Radon transform and its inversion. The image formation process and object reconstruction model are presented. The feasibility of this methodology is supported by numerical simulations.

  16. A simple algorithm for estimation of source-to-detector distance in Compton imaging

    International Nuclear Information System (INIS)

    Rawool-Sullivan, Mohini W.; Sullivan, John P.; Tornga, Shawn R.; Brumby, Steven P.

    2008-01-01

    Compton imaging is used to predict the location of gamma-emitting radiation sources. The X and Y coordinates of the source can be obtained using a back-projected image and a two-dimensional peak-finding algorithm. The emphasis of this work is to estimate the source-to-detector distance (Z). The algorithm presented uses the solid angle subtended by the reconstructed image at various source-to-detector distances. This algorithm was validated using both measured data from the prototype Compton imager (PCI) constructed at the Los Alamos National Laboratory and simulated data of the same imager. Results show this method can be applied successfully to estimate Z, and it provides a way of determining Z without prior knowledge of the source location. This method is faster than the methods that employ maximum likelihood method because it is based on simple back projections of Compton scatter data

  17. Conceptual design report of a compton polarimeter for CEBAF hall A

    Energy Technology Data Exchange (ETDEWEB)

    Bardin, G.; Cavata, C.; Neyret, D.; Frois, B.; Jorda, J.P.; Legoff, J.M.; Platchkov, S.; Steinmetz, L.; Juillard, M.; Authier, M.; Mangeot, P.; Rebourgeard, P.; Colombel, N.; Girardot, P.; Martinot, J.; Sellier, J.C.; Veyssiere, C. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l`Instrumentation Associee; Berthot, J.; Bertin, P.Y.; Breton, V.; Fonvieille, H.; Roblin, Y. [Institut National de Physique Nucleaire et de Physique des Particules (IN2P3), 75 - Paris (France); Chen, J.P. [Continuous Electron Beam Accelerator Facility, Newport News, VA (United States)

    1996-12-31

    This report describes the design of the Compton polarimeter for the Cebaf electron beam in End Station A. The method of Compton polarimeter is first introduced. It is shown that at CEBAF beam intensities, the use of standard visible LASER light gives too low counting rates. An amplification scheme of the LASER beam based on a high finesse optical cavity is proposed. Expected luminosities with and without such a cavity are given. The polarimeter setup, including a 4 dipole magnet chicane, a photon and an electron detector, is detailed. The various sources of systematic error on the electron beam polarization measurement are discussed. (author). 82 refs.

  18. Optimization of a Compton-suppression system by escape-peak ratio

    International Nuclear Information System (INIS)

    Niu, H.; Chao, J.H.; Wu, S.-C.

    1996-01-01

    A Compton-suppression system consisting of an HPGe central detector surrounded by eight BGO scintillators in an annular geometry was assembled. This system is dedicated to in-beam γ-ray measurements. The ratios of full-energy to single-escape peak and full-energy of double-escape peak, at γ-rays of 2754, 4443 and 6130 keV, were used to derive associated suppression factors in order to optimize detection conditions of the system. The suppression factors derived both from the escape peak ratios and the corresponding peak-to-Compton ratios of the γ-ray spectra are compared and discussed. This optimization technique may be of great significance for analyzing complicated spectra, where high-energy γ-rays are considered for analytical use. (Author)

  19. Effect of sample thickness on 511 keV single Compton-scattered gamma rays

    Energy Technology Data Exchange (ETDEWEB)

    Díaz-H, K. V., E-mail: kvdiazh@unal.edu.co; Cristancho, F. [Departamento de Física. Universidad Nacional de Colombia (Colombia)

    2016-07-07

    Gamma backscattering experiments were performed on metal foils varying some geometric parameters of the assembly. A collimated beam from a {sup 22}Na source impinges on aluminum sheets of dimensions 33.3×20.4×1.0 cm{sup 3} and iron sheets of (33.2×20.4×0.2) cm{sup 3}. The backscattered photons are detected by a 3″×3″ CsI scintillator detector placed at 90° to the incident beam. The experimental results show that thickness of metalic samples can be determined with a very small uncertainty.

  20. First demonstration of real-time gamma imaging by using a handheld Compton camera for particle therapy

    Energy Technology Data Exchange (ETDEWEB)

    Taya, T., E-mail: taka48138@ruri.waseda.jp [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Kataoka, J.; Kishimoto, A.; Iwamoto, Y.; Koide, A. [Research Institute for Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku, Tokyo 169-8555 (Japan); Nishio, T. [Graduate School of Biomedical and Health Science, Hiroshima University, 1-2-3, Kasumi, Minami-ku, Hiroshima-shi, Hiroshima (Japan); Kabuki, S. [School of Medicine, Tokai University, 143 Shimokasuya, Isehara-shi, Kanagawa (Japan); Inaniwa, T. [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage-ku, Chiba-shi, Chiba (Japan)

    2016-09-21

    The use of real-time gamma imaging for cancer treatment in particle therapy is expected to improve the accuracy of the treatment beam delivery. In this study, we demonstrated the imaging of gamma rays generated by the nuclear interactions during proton irradiation, using a handheld Compton camera (14 cm×15 cm×16 cm, 2.5 kg) based on scintillation detectors. The angular resolution of this Compton camera is ∼8° at full width at half maximum (FWHM) for a {sup 137}Cs source. We measured the energy spectra of the gamma rays using a LaBr{sub 3}(Ce) scintillator and photomultiplier tube, and using the handheld Compton camera, performed image reconstruction when using a 70 MeV proton beam to irradiate a water, Ca(OH){sub 2}, and polymethyl methacrylate (PMMA) phantom. In the energy spectra of all three phantoms, we found an obvious peak at 511 keV, which was derived from annihilation gamma rays, and in the energy spectrum of the PMMA phantom, we found another peak at 718 keV, which contains some of the prompt gamma rays produced from {sup 10}B. Therefore, we evaluated the peak positions of the projection from the reconstructed images of the PMMA phantom. The differences between the peak positions and the Bragg peak position calculated using simulation are 7 mm±2 mm and 3 mm±8 mm, respectively. Although we could quickly acquire online gamma imaging of both of the energy ranges during proton irradiation, we cannot arrive at a clear conclusion that prompt gamma rays sufficiently trace the Bragg peak from these results because of the uncertainty given by the spatial resolution of the Compton camera. We will develop a high-resolution Compton camera in the near future for further study. - Highlights: • Gamma imaging during proton irradiation by a handheld Compton camera is demonstrated. • We were able to acquire the online gamma-ray images quickly. • We are developing a high resolution Compton camera for range verification.

  1. Deeply virtual Compton scattering at Jefferson Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Biselli, Angela S. [Fairfield University - Department of Physics 1073 North Benson Road, Fairfield, CT 06430, USA; Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States)

    2016-08-01

    The generalized parton distributions (GPDs) have emerged as a universal tool to describe hadrons in terms of their elementary constituents, the quarks and the gluons. Deeply virtual Compton scattering (DVCS) on a proton or neutron ($N$), $e N \\rightarrow e' N' \\gamma$, is the process more directly interpretable in terms of GPDs. The amplitudes of DVCS and Bethe-Heitler, the process where a photon is emitted by either the incident or scattered electron, can be accessed via cross-section measurements or exploiting their interference which gives rise to spin asymmetries. Spin asymmetries, cross sections and cross-section differences can be connected to different combinations of the four leading-twist GPDs (${H}$, ${E}$, ${\\tilde{H}}$, ${\\tilde{E}}$) for each quark flavors, depending on the observable and on the type of target. This paper gives an overview of recent experimental results obtained for DVCS at Jefferson Laboratory in the halls A and B. Several experiments have been done extracting DVCS observables over large kinematics regions. Multiple measurements with overlapping kinematic regions allow to perform a quasi-model independent extraction of the Compton form factors, which are GPDs integrals, revealing a 3D image of the nucleon.

  2. Spatial resolution measurements of the advanced radiographic capability x-ray imaging system at energies relevant to Compton radiography

    Energy Technology Data Exchange (ETDEWEB)

    Hall, G. N., E-mail: hall98@llnl.gov; Izumi, N.; Landen, O. L.; Tommasini, R.; Holder, J. P.; Hargrove, D.; Bradley, D. K.; Lumbard, A.; Cruz, J. G.; Piston, K.; Bell, P. M.; Carpenter, A. C.; Palmer, N. E.; Felker, B.; Rekow, V.; Allen, F. V. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Lee, J. J.; Romano, E. [National Security Technologies LLC, 161 S Vasco Rd., Livermore, California 94551 (United States)

    2016-11-15

    Compton radiography provides a means to measure the integrity, ρR and symmetry of the DT fuel in an inertial confinement fusion implosion near peak compression. Upcoming experiments at the National Ignition Facility will use the ARC (Advanced Radiography Capability) laser to drive backlighter sources for Compton radiography experiments and will use the newly commissioned AXIS (ARC X-ray Imaging System) instrument as the detector. AXIS uses a dual-MCP (micro-channel plate) to provide gating and high DQE at the 40–200 keV x-ray range required for Compton radiography, but introduces many effects that contribute to the spatial resolution. Experiments were performed at energies relevant to Compton radiography to begin characterization of the spatial resolution of the AXIS diagnostic.

  3. Compton profiles and band structure calculations of CdS and CdTe

    International Nuclear Information System (INIS)

    Heda, N.L.; Mathur, S.; Ahuja, B.L.; Sharma, B.K.

    2007-01-01

    In this paper we present the isotropic Compton profiles of zinc-blende CdS and CdTe measured at an intermediate resolution of 0.39 a.u. using our 20 Ci 137 Cs Compton spectrometer. The electronic band structure calculations for both the zinc-blende structure compounds and also wurtzite CdS have been undertaken using various schemes of ab-initio linear combination of atomic orbitals calculations implemented in CRYSTAL03 code. The band structure and Mulliken's populations are reported using density functional scheme. In case of wurtzite CdS, our theoretical anisotropies in directional Compton profiles are compared with available experimental data. In case of both the zinc-blende compounds, the isotropic experimental profiles are found to be in better agreement with the present Hartree-Fock calculations. A study of the equal-valence-electron-density experimental profiles of zinc-blende CdS and CdTe shows that the CdS is more ionic than CdTe. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Future measurements of deeply virtual Compton scattering

    International Nuclear Information System (INIS)

    Korotkov, V.A.; Nowak, W.D.

    2001-09-01

    Prospects for future measurements of Deeply Virtual Compton Scattering are studied using different simple models for parameterizations of generalized parton distributions (GPDs). Measurements of the lepton charge and lepton beam helicity asymmetry will yield important input for theoretical models towards the future extraction of GPDs. The kinematics of the HERMES experiment, complemented with a recoil detector, was adopted to arrive at realistic projected statistical uncertainties. (orig.)

  5. Compton imaging with a highly-segmented, position-sensitive HPGe detector

    Energy Technology Data Exchange (ETDEWEB)

    Steinbach, T.; Hirsch, R.; Reiter, P.; Birkenbach, B.; Bruyneel, B.; Eberth, J.; Hess, H.; Lewandowski, L. [Universitaet zu Koeln, Institut fuer Kernphysik, Koeln (Germany); Gernhaeuser, R.; Maier, L.; Schlarb, M.; Weiler, B.; Winkel, M. [Technische Universitaet Muenchen, Physik Department, Garching (Germany)

    2017-02-15

    A Compton camera based on a highly-segmented high-purity germanium (HPGe) detector and a double-sided silicon-strip detector (DSSD) was developed, tested, and put into operation; the origin of γ radiation was determined successfully. The Compton camera is operated in two different modes. Coincidences from Compton-scattered γ-ray events between DSSD and HPGe detector allow for best angular resolution; while the high-efficiency mode takes advantage of the position sensitivity of the highly-segmented HPGe detector. In this mode the setup is sensitive to the whole 4π solid angle. The interaction-point positions in the 36-fold segmented large-volume HPGe detector are determined by pulse-shape analysis (PSA) of all HPGe detector signals. Imaging algorithms were developed for each mode and successfully implemented. The angular resolution sensitively depends on parameters such as geometry, selected multiplicity and interaction-point distances. Best results were obtained taking into account the crosstalk properties, the time alignment of the signals and the distance metric for the PSA for both operation modes. An angular resolution between 13.8 {sup circle} and 19.1 {sup circle}, depending on the minimal interaction-point distance for the high-efficiency mode at an energy of 1275 keV, was achieved. In the coincidence mode, an increased angular resolution of 4.6 {sup circle} was determined for the same γ-ray energy. (orig.)

  6. Relativistic wave equations and compton scattering

    International Nuclear Information System (INIS)

    Sutanto, S.H.; Robson, B.A.

    1998-01-01

    Full text: Recently an eight-component relativistic wave equation for spin-1/2 particles was proposed.This equation was obtained from a four-component spin-1/2 wave equation (the KG1/2 equation), which contains second-order derivatives in both space and time, by a procedure involving a linearisation of the time derivative analogous to that introduced by Feshbach and Villars for the Klein-Gordon equation. This new eight-component equation gives the same bound-state energy eigenvalue spectra for hydrogenic atoms as the Dirac equation but has been shown to predict different radiative transition probabilities for the fine structure of both the Balmer and Lyman a-lines. Since it has been shown that the new theory does not always give the same results as the Dirac theory, it is important to consider the validity of the new equation in the case of other physical problems. One of the early crucial tests of the Dirac theory was its application to the scattering of a photon by a free electron: the so-called Compton scattering problem. In this paper we apply the new theory to the calculation of Compton scattering to order e 2 . It will be shown that in spite of the considerable difference in the structure of the new theory and that of Dirac the cross section is given by the Klein-Nishina formula

  7. Very low background gamma spectrometer mounted in anti-Compton with NaI(Tl) for the study of glaciers and sediment samples; Spectrometrie gamma a tres bas niveau avec anti-Compton NaI(Tl), pour l`etude des glaciers et des sediments

    Energy Technology Data Exchange (ETDEWEB)

    Pinglot, J.F.; Pourchet, M. [Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. de Glaciologie

    1994-05-01

    The determination of natural and artificial radioactivities of snow (glaciers, polar ice-caps) or sediment samples (lakes, oceans), takes great benefit with the use of the superior resolution of high purity germanium detector, N type, in a broad energy range( 10 keV up to 1.6 MeV). This detector (relative efficiency: 20%), very low background specified, is mounted in anti-Compton with a 9`x 8` NaI(Tl) scintillator, also with low background. International standards, used with a quantitative software allows the determination of the efficiency curve and the isotopes identification and specific activity. The anti-Compton suppressed spectrometer exhibits a decrease of the background by a factor of ten, without any change in efficiencies. Applications of this spectrometer deal with samples from lake Titicaca and a glacier from Spitsbergen. (authors). 6 figs., 7 refs.

  8. Science Flight Program of the Nuclear Compton Telescope

    Science.gov (United States)

    Boggs, Steven

    This is the lead proposal for this program. We are proposing a 5-year program to perform the scientific flight program of the Nuclear Compton Telescope (NCT), consisting of a series of three (3) scientific balloon flights. NCT is a balloon-borne, wide-field telescope designed to survey the gamma-ray sky (0.2-5 MeV), performing high-resolution spectroscopy, wide-field imaging, and polarization measurements. NCT has been rebuilt as a ULDB payload under the current 2-year APRA grant. (In that proposal we stated our goal was to return at this point to propose the scientific flight program.) The NCT rebuild/upgrade is on budget and schedule to achieve flight-ready status in Fall 2013. Science: NCT will map the Galactic positron annihilation emission, shedding more light on the mysterious concentration of this emission uncovered by INTEGRAL. NCT will survey Galactic nucleosynthesis and the role of supernova and other stellar populations in the creation and evolution of the elements. NCT will map 26-Al and positron annihilation with unprecedented sensitivity and uniform exposure, perform the first mapping of 60-Fe, search for young, hidden supernova remnants through 44-Ti emission, and enable a host of other nuclear astrophysics studies. NCT will also study compact objects (in our Galaxy and AGN) and GRBs, providing novel measurements of polarization as well as detailed spectra and light curves. Design: NCT is an array of germanium gamma-ray detectors configured in a compact, wide-field Compton telescope configuration. The array is shielded on the sides and bottom by an active anticoincidence shield but is open to the 25% of the sky above for imaging, spectroscopy, and polarization measurements. The instrument is mounted on a zenith-pointed gondola, sweeping out ~50% of the sky each day. This instrument builds off the Compton telescope technique pioneered by COMPTEL on the Compton Gamma Ray Observatory. However, by utilizing modern germanium semiconductor strip detectors

  9. Complete $O(\\alpha)$ QED corrections to polarized Compton scattering

    CERN Document Server

    Denner, Ansgar

    1999-01-01

    The complete QED corrections of O(alpha) to polarized Compton scattering are calculated for finite electron mass and including the real corrections induced by the processes e^- gamma -> e^- gamma gamma and e^- gamma -> e^- e^- e^+. All relevant formulas are listed in a form that is well suited for a direct implementation in computer codes. We present a detailed numerical discussion of the O(alpha)-corrected cross section and the left-right asymmetry in the energy range of present and future Compton polarimeters, which are used to determine the beam polarization of high-energetic e^+- beams. For photons with energies of a few eV and electrons with SLC energies or smaller, the corrections are of the order of a few per mille. In the energy range of future e^+e^- colliders, however, they reach 1-2% and cannot be neglected in a precision polarization measurement.

  10. Recording {gamma} spectrometer with elimination of compton background; Spectrographe {gamma} enregistreur avec elimination du bruit de fond compton

    Energy Technology Data Exchange (ETDEWEB)

    Julliot, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1960-07-01

    This instrument, derived from the recording {gamma} spectrograph, gives better definition of photoelectric peaks by elimination of pulses caused by {gamma} photons incompletely absorbed in the scintillator (Compton effect). This system uses an original method devised by Peirson: the spectrum, devoid of photoelectric peak, supplied by a detector equipped with an anthracene scintillator, is cut off from the spectrum provided by a conventional detector equipped with a Nal (T1) scintillator. The regulation of the mechanical system, detector support and source allows the detection yields to be adjusted. The electronic system is identical in presentation with that of the recording spectrograph. (author) [French] Cet appareil derive du spectrographe {gamma} enregistreur permet d'obtenir une meilleure definition des pics photoelectriques, par elimination des impulsions provenant des photons {gamma} incompletement absorbes dans le scintillateur (effet Compton). Cet ensemble met en oeuvre une methode originale due a Peirson: le spectre, depourvu de pic photoelectrique, fourni par un detecteur, equipe avec un scintillateur d'anthracene, est retranche du spectre donne par un detecteur classique, equipe avec un scintillateur de NaI (T1). Le reglage de l'ensemble mecanique, support des detecteurs et de la source, permet d'ajuster les rendements de detection. L'ensemble electronique se presente sous un aspect identique a celui du spectrographe enregistreur. (auteur)

  11. Laser Compton polarimetry of proton beams

    International Nuclear Information System (INIS)

    Stillman, A.

    1995-01-01

    A need exists for non-destructive polarization measurements of the polarized proton beams in the AGS and, in the future, in RHIC. One way to make such measurements is to scatter photons from the polarized beams. Until now, such measurements were impossible because of the extremely low Compton scattering cross section from protons. Modern lasers now can provide enough photons per laser pulse not only to scatter from proton beams but also, at least in RHIC, to analyze their polarization

  12. Design of a Compton-suppression spectrometer and its application to the study of high-spin yrast states

    International Nuclear Information System (INIS)

    Aarts, H.J.M.

    1981-01-01

    Detailed γ-ray spectroscopy of high-spin states is hampered by transitions with low intensity on a high γ-ray background. An approach to enhance weak peaks in a spectrum in the reduction of the Compton background by means of a Compton-suppression spectrometer (CSS). Optimization of a CSS by means of Monte Carlo calculations is described. The investigation of high-spin states in the sd-shell nucleus 38 Ar with a Compton-suppression spectrometer is reported. With previously described techniques, in combination with p-γ coincidence measurements to establish an unambiguous level scheme, states up to Jsup(π) = 11 - could be identified and investigated. A gamma-gamma coincidence experiment on the nuclei 167 168 Hf is described with two Compton-suppression spectrometers. Yrast bands are followed, beyond the region of the first backbending, up to spin J = 37/2 and J = 28 for 167 Hf and 168 Hf, respectively. (Auth.)

  13. Double electron ionization in Compton scattering of high energy photons by helium atoms

    International Nuclear Information System (INIS)

    Amusia, M.Y.; Mikhailov, A.I.

    1995-01-01

    The cross section for double-electron ionization of two-electron atoms and ions in Compton scattering of high energy photons is calculated. It is demonstrated that its dependence on the incoming photon frequency is the same as that for single-electron ionization. The ratio of open-quotes double-to-singleclose quotes ionization in Compton scattering was found to be energy independent and almost identical with the corresponding value for photoionization. For the He atom it is 1.68%. This surprising result deserves experimental verification

  14. Double electron ionization in Compton scattering of high energy photons by helium atoms

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M.Y.; Mikhailov, A.I. [St. Petersburg Nuclear Physics Institute, Gatchina (Russian Federation)

    1995-08-01

    The cross section for double-electron ionization of two-electron atoms and ions in Compton scattering of high energy photons is calculated. It is demonstrated that its dependence on the incoming photon frequency is the same as that for single-electron ionization. The ratio of {open_quotes}double-to-single{close_quotes} ionization in Compton scattering was found to be energy independent and almost identical with the corresponding value for photoionization. For the He atom it is 1.68%. This surprising result deserves experimental verification.

  15. Development of Compton gamma-ray sources at LLNL

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  16. The GPD H and spin correlations in wide-angle Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, P. [Universitaet Wuppertal, Fachbereich Physik, Wuppertal (Germany)

    2017-06-15

    Wide-angle Compton scattering (WACS) is discussed within the handbag approach in which the amplitudes are given by products of hard subprocess amplitudes and form factors, specific to Compton scattering, which represent 1/x-moments of generalized parton distributions (GPDs). The quality of our present knowledge of these form factors and of the underlying GPDs is examined. As will be discussed in some detail the form factor R{sub A} and the underlying GPD H are poorly known. It is argued that future data on the spin correlations A{sub LL} and/or K{sub LL} will allow for an extraction of R{sub A} which can be used to constrain the large -t behavior of H. (orig.)

  17. Compton scatter correction in case of multiple crosstalks in SPECT imaging.

    Science.gov (United States)

    Sychra, J J; Blend, M J; Jobe, T H

    1996-02-01

    A strategy for Compton scatter correction in brain SPECT images was proposed recently. It assumes that two radioisotopes are used and that a significant portion of photons of one radioisotope (for example, Tc99m) spills over into the low energy acquisition window of the other radioisotope (for example, Tl201). We are extending this approach to cases of several radioisotopes with mutual, multiple and significant photon spillover. In the example above, one may correct not only the Tl201 image but also the Tc99m image corrupted by the Compton scatter originating from the small component of high energy Tl201 photons. The proposed extension is applicable to other anatomical domains (cardiac imaging).

  18. Einstein-Ehrenfest's radiation theory and Compton-Debye's kinetics

    International Nuclear Information System (INIS)

    Barranco, A.V.; Franca, H.M.

    1990-01-01

    Einstein and Ehrenfest's radiation theory is modified in order to introduce the efeects of random zero-point fields, characteristics of classical stochastic electrodynamics. As a result, the Compton and Debye's kinematic relations are obtained within the realm of a completely undulatory theory, that is, without having to consider the corpuscular character of the photon. (A.C.A.S.) [pt

  19. The 60 Month All-Sky Burst Alert Telescope Survey of Active Galactic Nucleus and the Anisotropy of Nearby AGNs

    Science.gov (United States)

    Ajello, M.; Alexander, D. M.; Greiner, J.; Madejeski, G. M.; Gehrels, N.; Burlon, D.

    2014-01-01

    Surveys above 10 keV represent one of the best resources to provide an unbiased census of the population of active galactic nuclei (AGNs). We present the results of 60 months of observation of the hard X-ray sky with Swift/Burst Alert Telescope (BAT). In this time frame, BAT-detected (in the 15-55 keV band) 720 sources in an all-sky survey of which 428 are associated with AGNs, most of which are nearby. Our sample has negligible incompleteness and statistics a factor of approx. 2 larger over similarly complete sets of AGNs. Our sample contains (at least) 15 bona fide Compton-thick AGNs and 3 likely candidates. Compton-thick AGNs represent approx. 5% of AGN samples detected above 15 keV. We use the BAT data set to refine the determination of the log N-log S of AGNs which is extremely important, now that NuSTAR prepares for launch, toward assessing the AGN contribution to the cosmic X-ray background. We show that the log N-log S of AGNs selected above 10 keV is now established to approx. 10% precision. We derive the luminosity function of Compton-thick AGNs and measure a space density of 7.9(+4.1/-2.9)× 10(exp -5)/cubic Mpc for objects with a de-absorbed luminosity larger than 2 × 10(exp 42) erg / s. As the BAT AGNs are all mostly local, they allow us to investigate the spatial distribution of AGNs in the nearby universe regardless of absorption. We find concentrations of AGNs that coincide spatially with the largest congregations of matter in the local (much < 85 Mpc) universe. There is some evidence that the fraction of Seyfert 2 objects is larger than average in the direction of these dense regions..

  20. Parity assignments in 140Ce up to 7 MeV using Compton polarimetry

    International Nuclear Information System (INIS)

    Buessing, M. A.; Elvers, M.; Endres, J.; Hasper, J.; Zilges, A.; Fritzsche, M.; Lindenberg, K.; Mueller, S.; Savran, D.; Sonnabend, K.

    2008-01-01

    Parity quantum numbers of J=1 states up to 7 MeV in the region of the Pygmy Dipole Resonance in 140 Ce were determined model independently by combining the methods of Nuclear Resonance Fluorescence and Compton polarimetry. For the first time the well-established method of Compton polarimetry was applied at such high energies. The experiment was performed using a fourfold segmented HPGe clover detector for the detection of the scattered photons. For all investigated dipole transitions asymmetries are found which correspond to negative parity of the excited states

  1. Compton Scattering of Quasi-Real Virtual Photons at LEP

    CERN Document Server

    Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery 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.; Barillere, 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.; Bohm, 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.; Deglon, P.; Debreczeni, J.; Degre, 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, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Jin, B.N.; Jindal, P.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, 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.; Mana, 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.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofiev, D.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosemann, C.; Rosenbleck, C.; Rosier-Lees, S.; Roth, Stefan; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, 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, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, 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, H.J.; Yeh, S.C.; Zalite, An.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

    2005-01-01

    Compton scattering of quasi-real virtual photons, gamma e+- -> gamma e+-, is studied with 0.6fb-1 of data collected by the L3 detector at the LEP e+e- collider at centre-of-mass energies root(s')=189-209GeV. 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 root(s')= 35GeV up to root(s')=175GeV, the highest energy at which Compton scattering was ever probed. The cross sections of the gamma e+- -> gamma e+- process as a function of root(s') and of the rest-frame scattering angle are measured, combined with previous L3 measurements down to root(s')~20GeV, and found to agree with the QED expectations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Danagoulian, Areg [Univ. of Illinois, Urbana-Champaign, IL (United States)

    2006-01-01

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

  3. Proton compton scattering in the resonance region

    International Nuclear Information System (INIS)

    Ishii, Takanobu.

    1979-12-01

    Differential cross sections of the proton Compton scattering have been measured in the energy range between 400 and 1150 MeV at CMS angles of 130 0 , 100 0 and 70 0 . The recoil proton was detected with a magnetic spectrometer using multi-wire proportional chambers and wire spark chambers. In coincidence with the proton, the scattered photon was detected with a lead glass Cerenkov counter of the total absorption type with a lead plate converter, and horizontal and vertical scintillation counter hodoscopes. The background due to the neutral pion photoproduction, was subtracted by using the kinematic relations between the scattered photon and the recoil proton. Theoretical calculations based on an isobar model with two components, that is, the resonance plus background, were done, and the photon couplings of the second resonance region were determined firstly from the proton Compton data. The results are that the helicity 1/2 photon couplings of P 11 (1470) and S 11 (1535), and the helicity 3/2 photon coupling of D 13 (1520) are consistent with those determined from the single pion photoproduction data, but the helicity 1/2 photon coupling of D 13 (1520) has a somewhat larger value than that from the single pion photoproduction data. (author)

  4. Electronic properties of Be and Al by Compton scattering technique

    International Nuclear Information System (INIS)

    Aguiar, J.C.; Di Rocco, H.O.

    2011-01-01

    In this work, electronic properties of beryllium and aluminum are examined by using Compton scattering technique. The method is based on the irradiation of samples using a beam narrow of mono- energetic photons of 59.54 keV product of radioactive decay of Am -241 . Scattered radiation is collected by a high resolution semiconductor detector positioned at an angle of 90°. The measured spectrum is commonly called Compton profile and contains useful information about the electronic structure of the material. The experimental results are compared with theoretical calculations such as density functional theory showing a good agreement. However, these results show some discrepancies with many libraries used in codes such as Monte Carlo simulation. Since these libraries are based on the values tabulated by Biggs, Mendelsohn and Mann 1975 thus overestimating the scattered radiation on the material. (authors) [es

  5. Strong anisotropy in the low temperature Compton profiles of ...

    Indian Academy of Sciences (India)

    Compton profiles of momentum distribution of conduction electrons in the orthorhombic phase of -Ga metal at low temperature are calculated in the band model for the three crystallographic directions (100), (010), and (001). Unlike the results at room temperature, previously reported by Lengeler, Lasser and Mair, the ...

  6. Virtual compton scattering at low energy

    International Nuclear Information System (INIS)

    Lhuillier, D.

    1997-09-01

    The work described in this PhD is a study of the Virtual Compton scattering (VCS) off the proton at low energy, below pion production threshold. Our experiment has been carried out at MAMI in the collaboration with the help of two high resolution spectrometers. Experimentally, the VCS process is the electroproduction of photons off a liquid hydrogen target. First results of data analysis including radiative corrections are presented and compared with low energy theorem prediction. VCS is an extension of the Real Compton Scattering. The virtuality of the incoming photon allows us to access new observables of the nucleon internal structure which are complementarity to the elastic form factors: the generalized polarizabilities (GP). They are function of the squared invariant mass of the virtual photo. The mass limit of these observables restore the usual electric and magnetic polarizabilities. Our experiment is the first measurement of the VCS process at a virtual photon mass equals 0.33 Ge V square. The experimental development presents the analysis method. The high precision needed in the absolute cross-section measurement required an accurate estimate of radiative corrections to the VCS. This new calculation, which has been performed in the dimensional regulation scheme, composes the theoretical part of this thesis. At low q', preliminary results agree with low energy theorem prediction. At higher q', substraction of low energy theorem contribution to extract GP is discussed. (author)

  7. Compton scattering on 208Pb

    International Nuclear Information System (INIS)

    Alberico, W.M.; Molinari, A.

    1982-01-01

    In this paper we briefly review the formalism of the nuclear Compton scattering in the frame of the low-energy theorems (LET). We treat the resonant terms of the amplitude, having collective intermediate nuclear states, as a superposition of Lorentz lines with energy, width and strength fixed by the photo-absorption experiments. The gauge terms are evaluated starting from a simple, but realistic, nuclear Hamiltonian. Dynamical nucleon-nucleon correlations are consistently taken into account, beyond those imposed by the Pauli principle. The comparison of the theoretical predictions with the data of elastic diffusion of photons from 208 Pb shows that LET are insufficient to account for the experiment. (orig.)

  8. Polarized γ source based on Compton backscattering in a laser cavity

    Directory of Open Access Journals (Sweden)

    V. Yakimenko

    2006-09-01

    Full Text Available We propose a novel gamma source suitable for generating a polarized positron beam for the next generation of electron-positron colliders, such as the International Linear Collider (ILC, and the Compact Linear Collider (CLIC. This 30-MeV polarized gamma source is based on Compton scattering inside a picosecond CO_{2} laser cavity generated from electron bunches produced by a 4-GeV linac. We identified and experimentally verified the optimum conditions for obtaining at least one gamma photon per electron. After multiplication at several consecutive interaction points, the circularly polarized gamma rays are stopped on a target, thereby creating copious numbers of polarized positrons. We address the practicality of having an intracavity Compton-polarized positron source as the injector for these new colliders.

  9. Nucleon Compton Scattering with Two Space-Like Photons

    International Nuclear Information System (INIS)

    Andrei Afanasev; I. Akushevich; N.P. Merenkov

    2002-01-01

    We calculate two-photon exchange effects for elastic electron-proton scattering at high momentum transfers. The corresponding nucleon Compton amplitude is defined by two space-like virtual photons that appear to have significant virtualities. We make predictions for (a) a single-spin beam asymmetry, and (b) a single-spin target asymmetry or recoil proton polarization caused by an unpolarized electron beam

  10. Estimation of Compton Imager Using Single 3D Position-Sensitive LYSO Scintillator: Monte Carlo Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Taewoong; Lee, Hyounggun; Kim, Younghak; Lee, Wonho [Korea University, Seoul (Korea, Republic of)

    2017-07-15

    The performance of a Compton imager using a single three-dimensional position-sensitive LYSO scintillator detector was estimated using a Monte Carlo simulation. The Compton imager consisted of a single LYSO scintillator with a pixelized structure. The size of the scintillator and each pixel were 1.3 × 1.3 × 1.3 cm{sup 3} and 0.3 × 0.3 × 0.3 cm{sup 3}, respectively. The order of γ-ray interactions was determined based on the deposited energies in each detector. After the determination of the interaction sequence, various types of reconstruction algorithms such as simple back-projection, filtered back-projection, and list-mode maximum-likelihood expectation maximization (LM-MLEM) were applied and compared with each other in terms of their angular resolution and signal-tonoise ratio (SNR) for several γ-ray energies. The LM-MLEM reconstruction algorithm exhibited the best performance for Compton imaging in maintaining high angular resolution and SNR. The two sources of {sup 137}Cs (662 keV) could be distinguishable if they were more than 17 ◦ apart. The reconstructed Compton images showed the precise position and distribution of various radiation isotopes, which demonstrated the feasibility of the monitoring of nuclear materials in homeland security and radioactive waste management applications.

  11. Compton profiles and electronic structure of HgBr{sub 2} and HgI{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, G.; Dashora, Alpa [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur, 313001 Rajasthan (India); Sharma, M. [Physics Division, State Forensic Science Laboratory, Jaipur, 302016 Rajasthan (India); Ahuja, B.L. [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur, 313001 Rajasthan (India)], E-mail: blahuja@yahoo.com

    2010-02-15

    In this paper, we present the first-ever experimental Compton line shapes of HgBr{sub 2} and HgI{sub 2} using {sup 137}Cs Compton spectrometer. To compare our experimental momentum densities, we have computed the Compton profiles using Hartree-Fock and density functional theory within linear combination of atomic orbitals. We have also computed the energy bands and density of states using the linear combination of atomic orbitals and full potential linearized augmented plane wave method. On the basis of equal-valence-electron-density profiles, it is seen that HgI{sub 2} is more covalent than HgBr{sub 2} which is in agreement with the valence charge densities. The experimental isotropic profiles are found to be relatively in better agreement with the Hartree-Fock data. We have also discussed the photoluminescence and detection properties of both the halides.

  12. X-ray dosimetry in mammography for W/Mo and Mo/Mo combinations utilizing Compton spectrometry

    International Nuclear Information System (INIS)

    Almeida Junior, Jose N.; Terini, Ricardo A.; Herdade, Silvio B.; Furquim, Tania A.C.

    2009-01-01

    Mean Glandular Dose (MGD) cannot be measured directly in mammography equipment. Therefore, methods based on Compton spectrometry are alternatives to evaluate dose distributions in a standard breast phantom, as well as mean glandular dose. In this work, a CdTe detector was used for the spectrometry measurements of radiation scattered by compton effect, at nearly 90, by a PMMA cylinder. For this, the reconstruction of primary beam spectra from the scattered ones has been made using Klein-Nishina theory and Compton formalism, followed by a determination of incident air kerma, absorbed dose values in the breast phantom and, finally, MGD. Incident and attenuated X-ray spectra and depth-dose distributions in a BR-12 phantom have been determined and are presented for the mammography range (28 to 35kV), showing good agreement with previous literature data, obtained with TLD. (author)

  13. A deep X-ray view of the bare AGN Ark 120. IV. XMM-Newton and NuSTAR spectra dominated by two temperature (warm, hot) Comptonization processes

    Science.gov (United States)

    Porquet, D.; Reeves, J. N.; Matt, G.; Marinucci, A.; Nardini, E.; Braito, V.; Lobban, A.; Ballantyne, D. R.; Boggs, S. E.; Christensen, F. E.; Dauser, T.; Farrah, D.; Garcia, J.; Hailey, C. J.; Harrison, F.; Stern, D.; Tortosa, A.; Ursini, F.; Zhang, W. W.

    2018-01-01

    Context. The physical characteristics of the material closest to supermassive black holes (SMBHs) are primarily studied through X-ray observations. However, the origins of the main X-ray components such as the soft X-ray excess, the Fe Kα line complex, and the hard X-ray excess are still hotly debated. This is particularly problematic for active galactic nuclei (AGN) showing a significant intrinsic absorption, either warm or neutral, which can severely distort the observed continuum. Therefore, AGN with no (or very weak) intrinsic absorption along the line of sight, so-called "bare AGN", are the best targets to directly probe matter very close to the SMBH. Aims: We perform an X-ray spectral analysis of the brightest and cleanest bare AGN known so far, Ark 120, in order to determine the process(es) at work in the vicinity of the SMBH. Methods: We present spectral analyses of data from an extensive campaign observing Ark 120 in X-rays with XMM-Newton (4 × 120 ks, 2014 March 18-24), and NuSTAR (65.5 ks, 2014 March 22). Results: During this very deep X-ray campaign, the source was caught in a high-flux state similar to the earlier 2003 XMM-Newton observation, and about twice as bright as the lower-flux observation in 2013. The spectral analysis confirms the "softer when brighter" behavior of Ark 120. The four XMM-Newton/pn spectra are characterized by the presence of a prominent soft X-ray excess and a significant Fe Kα complex. The continuum is very similar above about 3 keV, while significant variability is present for the soft X-ray excess. We find that relativistic reflection from a constant-density, flat accretion disk cannot simultaneously produce the soft excess, broad Fe Kα complex, and hard X-ray excess. Instead, Comptonization reproduces the broadband (0.3-79 keV) continuum well, together with a contribution from a mildly relativistic disk reflection spectrum. Conclusions: During this 2014 observational campaign, the soft X-ray spectrum of Ark 120 below 0

  14. Study and development of a spectrometer with Compton suppression and gamma coincidence counting

    International Nuclear Information System (INIS)

    Masse, D.

    1990-10-01

    This paper presents the characteristics of a spectrometer consisting of a Ge detector surrounded by a NaI(T1) detector that can operate in Compton-suppression and gamma-gamma coincidence modes. The criteria that led to this measurement configuration are discussed and the spectrometer performances are shown for 60 Co and 137 Cs gamma-ray sources. The results for the measurement of 189 Ir (Compton suppression) and for the measurement of 101 Rh (gamma-gamma coincidence) in the presence of other radioisotopes are given. 83 Rb and 105 Ag isotopes are also measured with this spectrometer [fr

  15. Infrared phenomena in quantum electrodynamics : II. Bremsstrahlung and compton scattering

    NARCIS (Netherlands)

    Haeringen, W. van

    The infrared aspects of quantum electrodynamics are discussed by treating two examples of scattering processes, bremsstrahlung and Compton scattering. As in the previous paper one uses a non-covariant diagram technique which gives very clear insight in the cancelling of infrared divergences between

  16. First experimental observation of double-photon Compton scattering using single gamma detector

    International Nuclear Information System (INIS)

    Sandhu, B.S.; Saddi, M.B.; Singh, B.; Ghumman, B.S.

    2003-01-01

    Full text: The phenomenon of double-photon Compton scattering has been successfully observed using single gamma detector, a technique avoiding the use of complicated slow-fast coincidence set-up used till now for observing this higher order process. Here doubly differentiated collision cross-section integrated over direction of one of the two final photons, the direction of other one being kept fixed, has been measured experimentally for 0.662 MeV incident gamma photons. The energy spectra of the detected photons are observed as a long tail to the single-photon Compton line on the lower side of the full energy peak in the recorded scattered energy spectrum. The present results are in agreement with theory of this process

  17. Directional Unfolded Source Term (DUST) for Compton Cameras.

    Energy Technology Data Exchange (ETDEWEB)

    Mitchell, Dean J.; Mitchell, Dean J.; Horne, Steven M.; O' Brien, Sean; Thoreson, Gregory G

    2018-03-01

    A Directional Unfolded Source Term (DUST) algorithm was developed to enable improved spectral analysis capabilities using data collected by Compton cameras. Achieving this objective required modification of the detector response function in the Gamma Detector Response and Analysis Software (GADRAS). Experimental data that were collected in support of this work include measurements of calibration sources at a range of separation distances and cylindrical depleted uranium castings.

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

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  19. A New Comptonization Model for Weakly Magnetized Accreting NS LMXBs

    Science.gov (United States)

    Paizis, A.; Farinelli, R.; Titarchuk, L.; Frontera, F.; Cocchi, M.; Ferrigno, C.

    2009-05-01

    We have developed a new Comptonization model to propose, for the first time, a self consistent physical interpretation of the complex spectral evolution seen in NS LMXBs. The model and its application to LMXBs are presented and compared to the Simbol-X expected capabilities.

  20. A Compton camera for spectroscopic imaging from 100 keV to 1 MeV

    International Nuclear Information System (INIS)

    Earnhart, J.R.D.

    1998-01-01

    A review of spectroscopic imaging issues, applications, and technology is presented. Compton cameras based on solid state semiconductor detectors stands out as the best system for the nondestructive assay of special nuclear materials. A camera for this application has been designed based on an efficient specific purpose Monte Carlo code developed for this project. Preliminary experiments have been performed which demonstrate the validity of the Compton camera concept and the accuracy of the code. Based on these results, a portable prototype system is in development. Proposed future work is addressed

  1. A portable Si/CdTe Compton camera and its applications to the visualization of radioactive substances

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Shin' ichiro, E-mail: takeda@astro.isas.jaxa.jp [Institute of Space and Astronautical Science (ISAS)/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Harayama, Atsushi [Institute of Space and Astronautical Science (ISAS)/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Ichinohe, Yuto [Institute of Space and Astronautical Science (ISAS)/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Odaka, Hirokazu [Institute of Space and Astronautical Science (ISAS)/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Watanabe, Shin; Takahashi, Tadayuki [Institute of Space and Astronautical Science (ISAS)/JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-0033 (Japan); Tajima, Hiroyasu [Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Genba, Kei; Matsuura, Daisuke; Ikebuchi, Hiroshi; Kuroda, Yoshikatsu [Mitsubishi Heavy Industries, 1200 Higashi-Tanaka, Komaki, Aichi 485-8561 (Japan); Tomonaka, Tetsuya [Mitsubishi Heavy Industry, 2-1-1 Shinhama, Arai-cho, Takasago, Hyogo 676-8686 (Japan)

    2015-07-01

    Gamma-ray imagers with the potential for visualizing the distribution of radioactive materials are required in the fields of astrophysics, medicine, nuclear applications, and homeland security. Based on the technology of the Si/CdTe Compton camera, we have manufactured the first commercial Compton camera for practical use. Through field tests in Fukushima, we demonstrated that the camera is capable of hot spot detection and the evaluation of radioactive decontamination.

  2. A portable Si/CdTe Compton camera and its applications to the visualization of radioactive substances

    International Nuclear Information System (INIS)

    Takeda, Shin'ichiro; Harayama, Atsushi; Ichinohe, Yuto; Odaka, Hirokazu; Watanabe, Shin; Takahashi, Tadayuki; Tajima, Hiroyasu; Genba, Kei; Matsuura, Daisuke; Ikebuchi, Hiroshi; Kuroda, Yoshikatsu; Tomonaka, Tetsuya

    2015-01-01

    Gamma-ray imagers with the potential for visualizing the distribution of radioactive materials are required in the fields of astrophysics, medicine, nuclear applications, and homeland security. Based on the technology of the Si/CdTe Compton camera, we have manufactured the first commercial Compton camera for practical use. Through field tests in Fukushima, we demonstrated that the camera is capable of hot spot detection and the evaluation of radioactive decontamination

  3. On the timing properties of germanium detectors: The centroid diagrams of prompt photopeaks and Compton events

    International Nuclear Information System (INIS)

    Penev, I.; Andrejtscheff, W.; Protochristov, Ch.; Zhelev, Zh.

    1987-01-01

    In the applications of the generalized centroid shift method with germanium detectors, the energy dependence of the time centroids of prompt photopeaks (zero-time line) and of Compton background events reveal a peculiar behavior crossing each other at about 100 keV. The effect is plausibly explained as associated with the ratio of γ-quanta causing the photoeffect and Compton scattering, respectively, at the boundaries of the detector. (orig.)

  4. Relativistic Turbulence with Strong Synchrotron and Synchrotron-Self-Compton Cooling

    Science.gov (United States)

    Uzdensky, D. A.

    2018-03-01

    Many relativistic plasma environments in high-energy astrophysics, including pulsar wind nebulae, hot accretion flows onto black holes, relativistic jets in active galactic nuclei and gamma-ray bursts, and giant radio lobes, are naturally turbulent. The plasma in these environments is often so hot that synchrotron and inverse-Compton (IC) radiative cooling becomes important. In this paper we investigate the general thermodynamic and radiative properties (and hence the observational appearance) of an optically thin relativistically hot plasma stirred by driven magnetohydrodynamic (MHD) turbulence and cooled by radiation. We find that if the system reaches a statistical equilibrium where turbulent heating is balanced by radiative cooling, the effective electron temperature tends to attain a universal value θ = kT_e/m_e c^2 ˜ 1/√{τ_T}, where τT = neσTL ≪ 1 is the system's Thomson optical depth, essentially independent of the strength of turbulent driving and hence of the magnetic field. This is because both MHD turbulent dissipation and synchrotron cooling are proportional to the magnetic energy density. We also find that synchrotron self-Compton (SSC) cooling and perhaps a few higher-order IC components are automatically comparable to synchrotron in this regime. The overall broadband radiation spectrum then consists of several distinct components (synchrotron, SSC, etc.), well separated in photon energy (by a factor ˜ τ_T^{-1}) and roughly equal in power. The number of IC peaks is checked by Klein-Nishina effects and depends logarithmically on τT and the magnetic field. We also examine the limitations due to synchrotron self-absorption, explore applications to Crab PWN and blazar jets, and discuss links to radiative magnetic reconnection.

  5. Performance studies towards a TOF-PET sensor using Compton scattering at plastic scintillators

    Science.gov (United States)

    Kuramoto, M.; Nakamori, T.; Gunji, S.; Kamada, K.; Shoji, Y.; Yoshikawa, A.; Aoki, T.

    2018-01-01

    We have developed a sensor head for a time-of-flight (TOF) PET scanner using plastic scintillators that have a very fast timing property. Given the very small cross section of photoelectric absorption in plastic scintillators at 511 keV, we use Compton scattering in order to compensate for detection efficiency. The detector will consist of two layers of scatterers and absorbers which are made of plastic and inorganic scintillators such as GAGG:Ce, respectively. Signals are read by monolithic Multi Pixel Photon Counters, and with energy deposits and interaction time stamps are being acquired. The scintillators are built to be capable of resolving interaction position in three dimensions, so that our system has also a function of depth-of-interaction (DOI) PET scanners. TOF resolution of ~ 200 ps (FWHM) is achieved in both cases of using the leading-edge discriminator and time-walk correction and using a configuration sensitive to DOI. Both the position resolution and spectroscopy are demonstrated using the prototype data acquisition system, with Compton scattering events subsequently being obtained. We also demonstrated that the background rejection technique using the Compton cone constraint could be valid with our system.

  6. Transverse tomography by Compton scattering scintigraphy

    International Nuclear Information System (INIS)

    Askienazy, S.; Lumbroso, J.; Lacaille, J.M.; Fredy, D.; Constans, J.P.; Barritault, L.

    The technique of tomography by Compton-scattering was applied to the exploration of the brain. Studies were carried out on phantoms and on patients and the first results are considered highly encouraging. On a phantom skull, holes at a depth of 7 cm are visible even on analogue documents and whatever their position with regard to the bone. On patients the ventricle cavities were revealed and comparisons with gas encephalograpy showed good agreement between the two techniques. The studies on phantoms also testified to the very low dose received by the patient: about 300 mRem for 2 million counts per section [fr

  7. Accurate Compton scattering measurements for N{sub 2} molecules

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, Kohjiro [Advanced Technology Research Center, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515 (Japan); Itou, Masayoshi; Tsuji, Naruki; Sakurai, Yoshiharu [Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Hosoya, Tetsuo; Sakurai, Hiroshi, E-mail: sakuraih@gunma-u.ac.jp [Department of Production Science and Technology, Gunma University, 29-1 Hon-cho, Ota, Gunma 373-0057 (Japan)

    2011-06-14

    The accurate Compton profiles of N{sub 2} gas were measured using 121.7 keV synchrotron x-rays. The present accurate measurement proves the better agreement of the CI (configuration interaction) calculation than the Hartree-Fock calculation and suggests the importance of multi-excitation in the CI calculations for the accuracy of wavefunctions in ground states.

  8. Room temperature Compton profiles of conduction electrons in α-Ga ...

    Indian Academy of Sciences (India)

    Room temperature Compton profiles of momentum distribution of conduction electrons in -Ga metal are calculated in band model. For this purpose, the conduction electron wave functions are determined in a temperature-dependent non-local model potential. The profiles calculated along the crystallographic directions, ...

  9. Room temperature Compton profiles of conduction electrons in α-Ga ...

    Indian Academy of Sciences (India)

    B P PANDA and N C MOHAPATRA*. Department of Physics, Chikiti Mahavidyalaya, Chikiti 761 010, India. £Department of Physics, Berhampur University, Berhampur 760 007, India. Email: ncmphy123@hotmail.com. MS received 18 January 2003; accepted 21 June 2003. Abstract. Room temperature Compton profiles of ...

  10. Experimental study on the CsI (Tl) crystal anti-compton detector in CDEX

    International Nuclear Information System (INIS)

    Liu Shukui; Yue Qian; Tang Changjian

    2012-01-01

    CDEX (China Dark matter Experiment) Collaboration will carry out direct search for dark matter with Ultra-Low Energy Threshold High Purity germanium (ULE-HPGe) detector at CJPL (China Jinping deep underground Laboratory). Before underground research, some experiments of the CsI (Tl) crystal Anti-Compton detector have been done on the ground, including light guide choice, wrapping material choice, height uniformity of CsI (Tl) crystal, side uniformity of CsI (Tl) crystal and the test results of all the crystals. Through the preliminary work on the ground, we have got some knowledge of the anti-compton detector and prepared for the underground experiment. (authors)

  11. A high-energy Compton polarimeter for the POET SMEX mission

    Science.gov (United States)

    Bloser, Peter F.; McConnell, Mark L.; Legere, Jason S.; Ertley, Camden D.; Hill, Joanne E.; Kippen, Marc; Ryan, James M.

    2014-07-01

    The primary science goal of the Polarimeters for Energetic Transients (POET) mission is to measure the polarization of gamma-ray bursts over a wide energy range, from X rays to soft gamma rays. The higher-energy portion of this band (50 - 500 keV) will be covered by the High Energy Polarimeter (HEP) instrument, a non-imaging, wide field of view Compton polarimeter. Incident high-energy photons will Compton scatter in low-Z, plastic scintillator detector elements and be subsequently absorbed in high-Z, CsI(Tl) scintillator elements; polarization is detected by measuring an asymmetry in the azimuthal scatter angle distribution. The HEP design is based on our considerable experience with the development and flight of the Gamma-Ray Polarimeter Experiment (GRAPE) balloon payload. We present the design of the POET HEP instrument, which incorporates lessons learned from the GRAPE balloon design and previous work on Explorer proposal efforts, and its expected performance on a two-year SMEX mission.

  12. Development and calibration of the tracking Compton/Pair telescope MEGA

    International Nuclear Information System (INIS)

    Kanbach, G.; Andritschke, R.; Zoglauer, A.; Ajello, M.; McConnell, M.L.; Macri, J.R.; Ryan, J.M.; Bloser, P.; Hunter, S.; DiCocco, G.; Kurfess, J.; Reglero, V.

    2005-01-01

    We describe the development and tests of the prototype for a new telescope for Medium Energy Gamma-ray Astronomy (MEGA) in the energy band 0.4-50 MeV. As a successor to COMPTEL and EGRET (at low energies), MEGA aims to improve the sensitivity for astronomical sources by at least an order of magnitude. It could thus fill the severe sensitivity gap between scheduled or operating hard-X-ray and high-energy gamma-ray missions and open the way for a future Advanced Compton Telescope. MEGA records and images γ-rays by completely tracking Compton and Pair creation events in a stack of double-sided Si-strip track detectors surrounded by a pixelated CsI calorimeter. A scaled down prototype has been built and we describe technical details of its design and properties. Results from calibrations using radioactive sources and from measurements with an accelerator generated, fully polarized, γ-ray beam are presented and an outlook to future plans with MEGA is given

  13. Electronic properties of mixed molybdenum dichalcogenide MoTeSe: LCAO calculations and Compton spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ahuja, Ushma [Department of Electrical Engineering, Veermata Jijabai Technological Institute, H. R. Mahajani Marg, Matunga (East), Mumbai 400019, Maharashtra (India); Kumar, Kishor; Joshi, Ritu [Department of Physics, University College of Science, M.L. Sukhadia University, Udaipur 313001, Rajasthan (India); Bhavsar, D.N. [Department of Physics, Bhavan' s Seth R.A. College of Science, Khanpur, Ahmedabad 380001, Gujarat (India); Heda, N.L., E-mail: nlheda@yahoo.co.in [Department of Pure and Applied Physics, University of Kota, Kota 324007, Rajasthan (India)

    2016-07-01

    We have employed linear combination of atomic orbitals (LCAO) method to compute the Mulliken’s population (MP), energy bands, density of states (DOS) and Compton profiles for hexagonal MoTeSe. The density functional theory (DFT) and hybridization of Hartree-Fock with DFT (B3LYP) have been used within the LCAO approximation. Performance of theoretical models has been tested by comparing the theoretical momentum densities with the experimental Compton profile of MoTeSe measured using {sup 137}Cs Compton spectrometer. It is seen that the B3LYP prescription gives a better agreement with the experimental data than other DFT based approximations. The energy bands and DOS depict an indirect band gap character in MoTeSe. In addition, a relative nature of bonding in MoTeSe and its isovalent MoTe{sub 2} is discussed in terms of equal-valence-electron-density (EVED) profiles. On the basis of EVED profiles it is seen that MoTeSe is more covalent than MoTe{sub 2}.

  14. A low-count reconstruction algorithm for Compton-based prompt gamma imaging

    Science.gov (United States)

    Huang, Hsuan-Ming; Liu, Chih-Chieh; Jan, Meei-Ling; Lee, Ming-Wei

    2018-04-01

    The Compton camera is an imaging device which has been proposed to detect prompt gammas (PGs) produced by proton–nuclear interactions within tissue during proton beam irradiation. Compton-based PG imaging has been developed to verify proton ranges because PG rays, particularly characteristic ones, have strong correlations with the distribution of the proton dose. However, accurate image reconstruction from characteristic PGs is challenging because the detector efficiency and resolution are generally low. Our previous study showed that point spread functions can be incorporated into the reconstruction process to improve image resolution. In this study, we proposed a low-count reconstruction algorithm to improve the image quality of a characteristic PG emission by pooling information from other characteristic PG emissions. PGs were simulated from a proton beam irradiated on a water phantom, and a two-stage Compton camera was used for PG detection. The results show that the image quality of the reconstructed characteristic PG emission is improved with our proposed method in contrast to the standard reconstruction method using events from only one characteristic PG emission. For the 4.44 MeV PG rays, both methods can be used to predict the positions of the peak and the distal falloff with a mean accuracy of 2 mm. Moreover, only the proposed method can improve the estimated positions of the peak and the distal falloff of 5.25 MeV PG rays, and a mean accuracy of 2 mm can be reached.

  15. Gamma-ray detection and Compton camera image reconstruction with application to hadron therapy

    International Nuclear Information System (INIS)

    Frandes, M.

    2010-09-01

    detection chain from Monte Carlo simulations to reconstruction of individual events, and finally to image reconstruction. A list-mode Maximum-Likelihood Expectation-Maximization (MLEM) algorithm was adopted to perform image reconstruction in conjunction with the imaging response, which has to depict the complex behavior of the detector. Modeling the imaging response requires complex calculations, considering the incident angle, all measured energies, the Compton scatter angle in the first interaction, the direction of scattered electron (when measured). In the simplest form, each event response is described by Compton cone profiles. The shapes of the profiles are approximated by 1D Gaussian distributions. A strong correlation was observed between pattern of the reconstructed high-energy gamma events, and location of the Bragg peak. The performance of the imaging technique illustrated by the HTI is a function of the detector performance in terms of detection efficiency, spatial and energy resolution, acquisition time, and the algorithms used to reconstruct the gamma-ray activity. Thus beside optimizations of the imaging system, the applied imaging algorithm has a high influence on the final reconstructed images. The HTI reconstructed images are corrupted by noise due to the low photon counts recorded, the uncertainties induced by finite energy resolution, Doppler broadening, the limited model used to estimate the imaging response, and the artifacts generated when iterating the MLEM algorithm. This noise is spatially varying and signal-dependent, representing a major obstacle for information extraction. Thus image de-noising techniques were investigated. A Wavelet based multi-resolution strategy of list-mode MLEM Regularization (WREM) was developed to reconstruct Compton images. At each iteration, a threshold-based processing step was integrated. The noise variance was estimated at each scale of the wavelet decomposition as the median value of the coefficients from the high

  16. Electron momentum density and Compton profile by a semi-empirical approach

    Science.gov (United States)

    Aguiar, Julio C.; Mitnik, Darío; Di Rocco, Héctor O.

    2015-08-01

    Here we propose a semi-empirical approach to describe with good accuracy the electron momentum densities and Compton profiles for a wide range of pure crystalline metals. In the present approach, we use an experimental Compton profile to fit an analytical expression for the momentum densities of the valence electrons. This expression is similar to a Fermi-Dirac distribution function with two parameters, one of which coincides with the ground state kinetic energy of the free-electron gas and the other resembles the electron-electron interaction energy. In the proposed scheme conduction electrons are neither completely free nor completely bound to the atomic nucleus. This procedure allows us to include correlation effects. We tested the approach for all metals with Z=3-50 and showed the results for three representative elements: Li, Be and Al from high-resolution experiments.

  17. NuSTAR reveals the Comptonizing corona of the broad-line radio galaxy 3C 382

    Energy Technology Data Exchange (ETDEWEB)

    Ballantyne, D. R.; Bollenbacher, J. M. [Center for Relativistic Astrophysics, School of Physics, Georgia Institute of Technology, Atlanta, GA 30332 (United States); Brenneman, L. W. [Harvard-Smithsonian CfA, 60 Garden Street MS-67, Cambridge, MA 02138 (United States); Madsen, K. K.; Baloković, M.; Harrison, F. A.; Walton, D. J. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Boggs, S. E. [Space Science Laboratory, University of California, Berkeley, CA 94720 (United States); Christensen, F. E.; Craig, W. W. [DTU SpaceNational Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Gandhi, P. [Department of Physics, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Hailey, C. J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Lohfink, A. M. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Marinucci, A. [Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, I-00146 Roma (Italy); Markwardt, C. B.; Zhang, W. W. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Stern, D., E-mail: david.ballantyne@physics.gatech.edu [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

    2014-10-10

    Broad-line radio galaxies (BLRGs) are active galactic nuclei that produce powerful, large-scale radio jets, but appear as Seyfert 1 galaxies in their optical spectra. In the X-ray band, BLRGs also appear like Seyfert galaxies, but with flatter spectra and weaker reflection features. One explanation for these properties is that the X-ray continuum is diluted by emission from the jet. Here, we present two NuSTAR observations of the BLRG 3C 382 that show clear evidence that the continuum of this source is dominated by thermal Comptonization, as in Seyfert 1 galaxies. The two observations were separated by over a year and found 3C 382 in different states separated by a factor of 1.7 in flux. The lower flux spectrum has a photon-index of Γ=1.68{sub −0.02}{sup +0.03}, while the photon-index of the higher flux spectrum is Γ=1.78{sub −0.03}{sup +0.02}. Thermal and anisotropic Comptonization models provide an excellent fit to both spectra and show that the coronal plasma cooled from kT{sub e} = 330 ± 30 keV in the low flux data to 231{sub −88}{sup +50} keV in the high flux observation. This cooling behavior is typical of Comptonizing corona in Seyfert galaxies and is distinct from the variations observed in jet-dominated sources. In the high flux observation, simultaneous Swift data are leveraged to obtain a broadband spectral energy distribution and indicates that the corona intercepts ∼10% of the optical and ultraviolet emitting accretion disk. 3C 382 exhibits very weak reflection features, with no detectable relativistic Fe Kα line, that may be best explained by an outflowing corona combined with an ionized inner accretion disk.

  18. Gamma-ray detection and Compton camera image reconstruction with application to hadron therapy; Detection des rayons gamma et reconstruction d'images pour la camera Compton: Application a l'hadrontherapie

    Energy Technology Data Exchange (ETDEWEB)

    Frandes, M.

    2010-09-15

    detection chain from Monte Carlo simulations to reconstruction of individual events, and finally to image reconstruction. A list-mode Maximum-Likelihood Expectation-Maximization (MLEM) algorithm was adopted to perform image reconstruction in conjunction with the imaging response, which has to depict the complex behavior of the detector. Modeling the imaging response requires complex calculations, considering the incident angle, all measured energies, the Compton scatter angle in the first interaction, the direction of scattered electron (when measured). In the simplest form, each event response is described by Compton cone profiles. The shapes of the profiles are approximated by 1D Gaussian distributions. A strong correlation was observed between pattern of the reconstructed high-energy gamma events, and location of the Bragg peak. The performance of the imaging technique illustrated by the HTI is a function of the detector performance in terms of detection efficiency, spatial and energy resolution, acquisition time, and the algorithms used to reconstruct the gamma-ray activity. Thus beside optimizations of the imaging system, the applied imaging algorithm has a high influence on the final reconstructed images. The HTI reconstructed images are corrupted by noise due to the low photon counts recorded, the uncertainties induced by finite energy resolution, Doppler broadening, the limited model used to estimate the imaging response, and the artifacts generated when iterating the MLEM algorithm. This noise is spatially varying and signal-dependent, representing a major obstacle for information extraction. Thus image de-noising techniques were investigated. A Wavelet based multi-resolution strategy of list-mode MLEM Regularization (WREM) was developed to reconstruct Compton images. At each iteration, a threshold-based processing step was integrated. The noise variance was estimated at each scale of the wavelet decomposition as the median value of the coefficients from the high

  19. Research building gamma Compton scattering measurement system and related exercises for training nuclear human resources

    International Nuclear Information System (INIS)

    Mai Xuan Phong; Nguyen Van Hung; Pham Xuan Hai; Le Van Ngoc; Nguyen Xuan Hai; Dang Lanh; Tran Quoc Duong

    2013-01-01

    In this subject we have designed and manufactured Compton scattering gamma measurement system based on the calculated optimal configuration as well as the conditions of protect radiation by using Monte-Carlo simulation program and fabrication with the optimal conditions were selected. Monte-Carlo simulation calculation of Compton scattering gamma follow different angles on copper, surveying gamma radiation attenuation characteristics of materials: lead, iron, aluminum, and compared with the experimental results performed on the same measurement system has been built and given for evaluation, comments. (author)

  20. Accurate measurement of the electron beam polarization in JLab Hall A using Compton polarimetry

    International Nuclear Information System (INIS)

    Escoffier, S.; Bertin, P.Y.; Brossard, M.; Burtin, E.; Cavata, C.; Colombel, N.; Jager, C.W. de; Delbart, A.; Lhuillier, D.; Marie, F.; Mitchell, J.; Neyret, D.; Pussieux, T.

    2005-01-01

    A major advance in accurate electron beam polarization measurement has been achieved at Jlab Hall A with a Compton polarimeter based on a Fabry-Perot cavity photon beam amplifier. At an electron energy of 4.6GeV and a beam current of 40μA, a total relative uncertainty of 1.5% is typically achieved within 40min of data taking. Under the same conditions monitoring of the polarization is accurate at a level of 1%. These unprecedented results make Compton polarimetry an essential tool for modern parity-violation experiments, which require very accurate electron beam polarization measurements

  1. Accurate calculation of the differential cross section of compton scattering with electron mixed chain propagator in SM

    International Nuclear Information System (INIS)

    Chen Xuewen; Fang Zhenyun; Shi Chengye

    2012-01-01

    By using the electroweak standard model (SM), we analyzed the framework of electron mixed chain propagator which composed of serious of different physical loops participating in electroweak interaction and completed the relevant analytical calculation. Then, we obtained the analytical result of electron mixed chain propagator. By applying our result to Compton scattering, the differential cross section of Compton scattering dσ SM (chain) /dcosθ is counted accurately. This result is compared with the lowest order differential cross section dσ (tree) /dcosθ and the electronic chain propagator Compton scattering differential cross section dσ QED (chain) /dcosθ in quantum electrodynamics (QED). It can be seen that dσ SM (chain ) /dcosθ can show the radiation correction more subtly than dσ QED (chain) /dcosθ. (authors)

  2. Correlation between active layer thickness and ambient gas stability in IGZO thin-film transistors

    International Nuclear Information System (INIS)

    Gao, Xu; Mao, Bao-Hua; Wang, Sui-Dong; Lin, Meng-Fang; Shimizu, Maki; Mitoma, Nobuhiko; Kizu, Takio; Ou-Yang, Wei; Tsukagoshi, Kazuhito; Nabatame, Toshihide; Liu, Zhi

    2017-01-01

    Decreasing the active layer thickness has been recently reported as an alternative way to achieve fully depleted oxide thin-film transistors for the realization of low-voltage operations. However, the correlation between the active layer thickness and device resistivity to environmental changes is still unclear, which is important for the optimized design of oxide thin-film transistors. In this work, the ambient gas stability of IGZO thin-film transistors is found to be strongly correlated to the IGZO thickness. The TFT with the thinnest IGZO layer shows the highest intrinsic electron mobility in a vacuum, which is greatly reduced after exposure to O 2 /air. The device with a thick IGZO layer shows similar electron mobility in O 2 /air, whereas the mobility variation measured in the vacuum is absent. The thickness dependent ambient gas stability is attributed to a high-mobility region in the IGZO surface vicinity with less sputtering-induced damage, which will become electron depleted in O 2 /air due to the electron transfer to adsorbed gas molecules. The O 2 adsorption and deduced IGZO surface band bending is demonstrated by the ambient-pressure x-ray photoemission spectroscopy results. (paper)

  3. Use of primary beam filtration in estimating mass attenuation coefficients by Compton scattering

    International Nuclear Information System (INIS)

    O'Connor, B.H.; Chang, W.J.

    1985-01-01

    Mass attenuation coefficients (MACs) are frequently estimated over a range of wavelengths in x-ray spectrometry from the intensity of the Compton peak I /SUB C/ associated with a prominent tube line. The MAC μ /SUB ll/ at wavelength lambda is estimated from the MAC at the Compton wavelength lambda /SUB C/ with the approximations μ /SUB ll/ α μ /SUB C/ and μ /SUB C/ α l/I /SUB C/ , Systematic errors may introduce absorption edge bias (AEB) effects into the results, caused by sample components with absorption edges between lambda /SUB C/ and lambda. A procedure is described which eliminates AEB effects by measuring I /SUB C/ using emission radiation from a primary beam filter

  4. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    International Nuclear Information System (INIS)

    Rosikhin, Ahmad; Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto

    2015-01-01

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO 2 in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO 2 layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices

  5. Enhanced photocurrent density in graphene/Si based solar cell (GSSC) by optimizing active layer thickness

    Energy Technology Data Exchange (ETDEWEB)

    Rosikhin, Ahmad, E-mail: a.rosikhin86@yahoo.co.id; Hidayat, Aulia Fikri; Syuhada, Ibnu; Winata, Toto, E-mail: toto@fi.itb.ac.id [Department of physics, physics of electronic materials research division Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung Jl. Ganesha 10, Bandung 40132, Jawa Barat – Indonesia (Indonesia)

    2015-12-29

    Thickness dependent photocurrent density in active layer of graphene/Si based solar cell has been investigated via analytical – simulation study. This report is a preliminary comparison of experimental and analytical investigation of graphene/Si based solar cell. Graphene sheet was interfaced with Si thin film forming heterojunction solar cell that was treated as a device model for photocurrent generator. Such current can be enhanced by optimizing active layer thickness and involving metal oxide as supporting layer to shift photons absorption. In this case there are two type of devices model with and without TiO{sub 2} in which the silicon thickness varied at 20 – 100 nm. All of them have examined and also compared with each other to obtain an optimum value. From this calculation it found that generated currents almost linear with thickness but there are saturated conditions that no more enhancements will be achieved. Furthermore TiO{sub 2} layer is effectively increases photon absorption but reducing device stability, maximum current is fluctuates enough. This may caused by the disturbance of excitons diffusion and resistivity inside each layer. Finally by controlling active layer thickness, it is quite useful to estimate optimization in order to develop the next solar cell devices.

  6. A novel comparison of Møller and Compton electron-beam polarimeters

    Directory of Open Access Journals (Sweden)

    J.A. Magee

    2017-03-01

    Full Text Available We have performed a novel comparison between electron-beam polarimeters based on Møller and Compton scattering. A sequence of electron-beam polarization measurements were performed at low beam currents (<5 μA during the Qweak experiment in Hall-C at Jefferson Lab. These low current measurements were bracketed by the regular high current (180 μA operation of the Compton polarimeter. All measurements were found to be consistent within experimental uncertainties of 1% or less, demonstrating that electron polarization does not depend significantly on the beam current. This result lends confidence to the common practice of applying Møller measurements made at low beam currents to physics experiments performed at higher beam currents. The agreement between two polarimetry techniques based on independent physical processes sets an important benchmark for future precision asymmetry measurements that require sub-1% precision in polarimetry.

  7. Experimental confirmation of neoclassical Compton scattering theory

    Energy Technology Data Exchange (ETDEWEB)

    Aristov, V. V., E-mail: aristov@iptm.ru [Russian Academy of Sciences, Institute of Microelectronics Technology and High Purity Materials (Russian Federation); Yakunin, S. N. [National Research Centre “Kurchatov Institute” (Russian Federation); Despotuli, A. A. [Russian Academy of Sciences, Institute of Microelectronics Technology and High Purity Materials (Russian Federation)

    2013-12-15

    Incoherent X-ray scattering spectra of diamond and silicon crystals recorded on the BESSY-2 electron storage ring have been analyzed. All spectral features are described well in terms of the neoclassical scattering theory without consideration for the hypotheses accepted in quantum electrodynamics. It is noted that the accepted tabular data on the intensity ratio between the Compton and Rayleigh spectral components may significantly differ from the experimental values. It is concluded that the development of the general theory (considering coherent scattering, incoherent scattering, and Bragg diffraction) must be continued.

  8. The development of a Compton lung densitometer

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-11-01

    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.

  9. The development of a Compton lung densitometer

    International Nuclear Information System (INIS)

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

    1988-11-01

    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

  10. WITNESSING THE KEY EARLY PHASE OF QUASAR EVOLUTION: AN OBSCURED ACTIVE GALACTIC NUCLEUS PAIR IN THE INTERACTING GALAXY IRAS 20210+1121

    International Nuclear Information System (INIS)

    Piconcelli, Enrico; Fiore, Fabrizio; Maiolino, Roberto; Nicastro, Fabrizio; Vignali, Cristian; Bianchi, Stefano; Mathur, Smita; Guainazzi, Matteo; Lanzuisi, Giorgio

    2010-01-01

    We report the discovery of an active galactic nucleus (AGN) pair in the interacting galaxy system IRAS 20210+1121 at z = 0.056. An XMM-Newton observation reveals the presence of an obscured (N H ∼ 5 x 10 23 cm -2 ), Seyfert-like (L 2-10keV = 4.7 x 10 42 erg s -1 ) nucleus in the northern galaxy, which lacks unambiguous optical AGN signatures. Our spectral analysis also provides strong evidence that the IR-luminous southern galaxy hosts a Type 2 quasar embedded in a bright starburst emission. In particular, the X-ray primary continuum from the nucleus appears totally depressed in the XMM-Newton band as expected in the case of a Compton-thick absorber, and only the emission produced by Compton scattering ('reflection') of the continuum from circumnuclear matter is seen. As such, IRAS 20210+1121 seems to provide an excellent opportunity to witness a key, early phase in the quasar evolution predicted by the theoretical models of quasar activation by galaxy collisions.

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

    International Nuclear Information System (INIS)

    Esmaeili-sani, Vahid; Moussavi-zarandi, Ali; Boghrati, Behzad; Afarideh, Hossein

    2012-01-01

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

  12. Development of a liquid xenon Compton telescope dedicated to functional medical imaging; Etude et developpement d'un telescope compton au xenon liquide dedie a l'imagerie medicale fonctionnelle

    Energy Technology Data Exchange (ETDEWEB)

    Grignon, C

    2007-12-15

    Functional imaging is a technique used to locate in three dimensions the position of a radiotracer previously injected in a patient. The two main modalities used for a clinical application to detect tumors, the SPECT and the PET, use solid scintillators as a detection medium. The objective of this thesis was to investigate the possibility of using liquid xenon in order to benefit from the intrinsic properties of this medium in functional imaging. The feasibility study of such a device has been performed by taking into account the technical difficulties specific to the liquid xenon. First of all, simulations of a liquid xenon PET has been performed using Monte-Carlo methods. The results obtained with a large liquid xenon volume are promising : we can expect a reduction of the injected activity of radiotracer, an improvement of the spatial resolution of the image and a parallax free camera. The second part of the thesis was focused on the development of a new concept of medical imaging, the three gamma imaging, based on the use of a new emitter: the 44 scandium. Associated to a classical PET camera, the Compton telescope is used to infer the incoming direction of the third gamma ray by triangulation. Therefore, it is possible to reconstruct the position of each emitter in three dimensions. This work convinced the scientific community to support the construction and characterization of a liquid xenon Compton telescope. The first camera dedicated to small animal imaging should then be operational in 2009. (author)

  13. Hard X-ray emission mechanism of active galactic nuclei sources

    International Nuclear Information System (INIS)

    Liang, E.P.T.

    1979-01-01

    Within the framework of unsaturated Compton disk accretion onto a supermassive black hole as model for power-law active galactic nuclei X-ray sources (as opposed to the synchro-Compton model), we compare the hot inner disk model of Shapiro, Lightman, and Eardley and the disk corona model with balanced conduction and Compton losses. Both can generate electron temperatures > or approx. =10 9 K in the supermassive case but promise other observable distinctions. The sandwich configuration of the disk corona provides a natural explanation of why Comptonization is unsaturated

  14. Connections between Compton scattering and pion photoproduction in the delta region

    International Nuclear Information System (INIS)

    Mukhopadhyay, N.C.; Benmerrouche, M.

    1992-01-01

    Using textbook tools like analyticity, unitarity and optical theorem, the authors discuss the relationship between pion-nucleon scattering, pion photoproduction and Compton scattering in the Δ(1232) resonance region. They review the relevant data and draw conclusions pertinent to the QCD-inspired models. 27 refs

  15. Thiophene Rings Improve the Device Performance of Conjugated Polymers in Polymer Solar Cells with Thick Active Layers

    NARCIS (Netherlands)

    Duan, C.; Gao, K.; Colberts, F. J. M.; Liu, F.; Meskers, S. C. J.; Wienk, M. M.; Janssen, R. A. J.

    2017-01-01

    Developing novel materials that tolerate thickness variations of the active layer is critical to further enhance the efficiency of polymer solar cells and enable large-scale manufacturing. Presently, only a few polymers afford high efficiencies at active layer thickness exceeding 200 nm and

  16. Dyson Orbitals, Quasi-Particle effects and Compton scattering

    OpenAIRE

    Barbiellini, B.; Bansil, A.

    2004-01-01

    Dyson orbitals play an important role in understanding quasi-particle effects in the correlated ground state of a many-particle system and are relevant for describing the Compton scattering cross section beyond the frameworks of the impulse approximation (IA) and the independent particle model (IPM). Here we discuss corrections to the Kohn-Sham energies due to quasi-particle effects in terms of Dyson orbitals and obtain a relatively simple local form of the exchange-correlation energy. Illust...

  17. Formal analogy between Compton scattering and Doppler effect

    DEFF Research Database (Denmark)

    Nielsen, A.; Olsen, Jørgen Seir

    1966-01-01

    Viewed from the scatterer, the energy of the incoming photon or particle is equal to that of the outgoing, and the angle of incidence is equal to the angle of reflection, when the direction of the velocity of the scatterer after the collision is taken as reference. This paper sets out to prove...... this statement in a more simple and direct way. The authors only consider the Compton scatting process as it is quite analogous to the particle case....

  18. Investigation on feasibility and detection limits for determination of coating film thickness by neutron activation analysis

    International Nuclear Information System (INIS)

    Yao Maoying; Xu Jiayun; Zhang Dida; Yang Zunyong; Yao Zhenqiang; Wang Mingqiu; Gao Dangzhong

    2010-01-01

    A method for the determination of coating film thickness by neutron activation was proposed in this paper. After Au, Al and Cu et al.films were activated with a Am-Be neutron source, the characteristic γ-rays emitted by the activated nuclides in the films were counted with a HPGe γ spectrometer. The detection limits of film thickness by using a nuclear reactor neutron source were deduced on the basis of the γ-ray counts and the Monte-Carlo simulated detection efficiencies. The possible detection limits are typically 4-5 orders of magnitude better than those by fluorescent X-ray method, which is currently widely used to determine coating film thickness. (authors)

  19. Myosin binding protein-C activates thin filaments and inhibits thick filaments in heart muscle cells.

    Science.gov (United States)

    Kampourakis, Thomas; Yan, Ziqian; Gautel, Mathias; Sun, Yin-Biao; Irving, Malcolm

    2014-12-30

    Myosin binding protein-C (MyBP-C) is a key regulatory protein in heart muscle, and mutations in the MYBPC3 gene are frequently associated with cardiomyopathy. However, the mechanism of action of MyBP-C remains poorly understood, and both activating and inhibitory effects of MyBP-C on contractility have been reported. To clarify the function of the regulatory N-terminal domains of MyBP-C, we determined their effects on the structure of thick (myosin-containing) and thin (actin-containing) filaments in intact sarcomeres of heart muscle. We used fluorescent probes on troponin C in the thin filaments and on myosin regulatory light chain in the thick filaments to monitor structural changes associated with activation of demembranated trabeculae from rat ventricle by the C1mC2 region of rat MyBP-C. C1mC2 induced larger structural changes in thin filaments than calcium activation, and these were still present when active force was blocked with blebbistatin, showing that C1mC2 directly activates the thin filaments. In contrast, structural changes in thick filaments induced by C1mC2 were smaller than those associated with calcium activation and were abolished or reversed by blebbistatin. Low concentrations of C1mC2 did not affect resting force but increased calcium sensitivity and reduced cooperativity of force and structural changes in both thin and thick filaments. These results show that the N-terminal region of MyBP-C stabilizes the ON state of thin filaments and the OFF state of thick filaments and lead to a novel hypothesis for the physiological role of MyBP-C in the regulation of cardiac contractility.

  20. Choroidal thickness and myopia in relation to physical activity during childhood

    DEFF Research Database (Denmark)

    Lundberg, Kristian; Jacobsen, Nina; Vestergaard, Anders Højslet

    Purpose: Decreasing physical activity (PA) has been suggested to be a driving force behind the rapid increase of myopia worldwide. The possible protective effects of PA might be through increased blood flow and subsequent change in thickness of the choroid. The purpose of this study......, L, M and V PA (2.31 µm/% (p=0.22), -3.99 µm/% (p=0.15), -5.43 µm/% (p=0.57) and -0.53 µm/% (p=0.95), respectively). Conclusions: We found no association between physical activity and the choroidal thickness, axial length or refractive error. However, the choroid was thinner in myopic eyes......±59 µm (3 mm zone), respectively. All CT measurements were thinner in myopic eyes (psex-adjusted linear regression there were no associations between PA and SE, AL or any CT measurements. There was no association between accumulated PA and the overall CT for SED...

  1. ITEM-QM solutions for EM problems in image reconstruction exemplary for the Compton Camera

    CERN Document Server

    Pauli, Josef; Anton, G

    2002-01-01

    Imaginary time expectation maximation (ITEM), a new algorithm for expectation maximization problems based on the quantum mechanics energy minimalization via imaginary (euclidian) time evolution is presented. Both (the algorithm as well as the implementation (http://www.johannes-pauli.de/item/index.html) are published under the terms of General GNU public License (http://www.gnu.org/copyleft/gpl.html). Due to its generality ITEM is applicable to various image reconstruction problems like CT, PET, SPECT, NMR, Compton Camera, tomosynthesis as well as any other energy minimization problem. The choice of the optimal ITEM Hamiltonian is discussed and numerical results are presented for the Compton Camera.

  2. Electronic structure of Ni{sub 2}TiAl: Theoretical aspects and Compton scattering measurement

    Energy Technology Data Exchange (ETDEWEB)

    Sahariya, Jagrati [Department of Physics, University College of Science, M.L. Sukhadia University, Durga Nursery Road, Udaipur 313001, Rajasthan (India); Ahuja, B.L., E-mail: blahuja@yahoo.com [Department of Physics, University College of Science, M.L. Sukhadia University, Durga Nursery Road, Udaipur 313001, Rajasthan (India)

    2012-11-01

    In this paper, we report electron momentum density of Ni{sub 2}TiAl alloy using an in-house 20 Ci {sup 137}Cs (661.65 keV) Compton spectrometer. The experimental data have been analyzed in terms of energy bands and density of states computed using linear combination of atomic orbitals (LCAO) method. In the LCAO computations, we have considered local density approximation, generalized gradient approximation and recently developed second order generalized gradient approximation within the frame work of density functional theory. Anisotropies in theoretical Compton profiles along [1 0 0], [1 1 0] and [1 1 1] directions are also explained in terms of energy bands.

  3. On a low intensity 241 Am Compton spectrometer for measurement ...

    Indian Academy of Sciences (India)

    In this paper, a new design and construction of a low intensity (100 mCi) 241Am -ray Compton spectrometer is presented. The planar spectrometer is based on a small disc source with the shortest geometry. Measurement of the momentum density of polycrystalline Al is used to evaluate the performance of the new design.

  4. Rayleigh to Compton ratio scatter tomography applied to breast cancer diagnosis: A preliminary computational study

    International Nuclear Information System (INIS)

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

    2014-01-01

    In the present work, a tomographic technique based on Rayleigh to Compton scattering ratio (R/C) was studied using computational simulation in order to assess its application to breast cancer diagnosis. In this preliminary study, some parameters that affect the image quality were evaluated, such as: (i) energy beam, (ii) size and glandularity of the breast, and (iii) statistical count noise. The results showed that the R/C contrast increases with increasing photon energy and decreases with increasing glandularity of the sample. The statistical noise showed to be a significant parameter, although the quality of the obtained images was acceptable for a considerable range of noise level. The preliminary results suggest that the R/C tomographic technique has a potential of being applied as a complementary tool in the breast cancer diagnostic. - Highlights: ► A tomographic technique based on Rayleigh to Compton scattering ratio is proposed in order to study breast tissues. ► The Rayleigh to Compton scattering ratio technique is compared with conventional transmission technique. ► The influence of experimental parameters (energy, sample, detection system) is studied

  5. Chandra Observations of Galaxy Zoo Mergers: Frequency of Binary Active Nuclei in Massive Mergers

    Science.gov (United States)

    Teng, Stacy H.; Schawinski, Kevin; Urry, C. Megan; Darg, Dan W.; Kaviraj, Sugata; Oh, Kyuseok; Bonning, Erin W.; Cardamone, Carolin N.; Keel, William C.; Lintott, Chris J.; hide

    2012-01-01

    We present the results from a Chandra pilot study of 12 massive galaxy mergers selected from Galaxy Zoo. The sample includes major mergers down to a host galaxy mass of 1011 M that already have optical AGN signatures in at least one of the progenitors. We find that the coincidences of optically selected active nuclei with mildly obscured (N(sub H) approx merger is found to have confirmed binary X-ray nuclei, though the X-ray emission from its southern nucleus could be due solely to star formation. Thus, the occurrences of binary AGN in these mergers are rare (0-8%), unless most merger-induced active nuclei are very heavily obscured or Compton thick.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-12-05

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

  7. Compton camera imaging and the cone transform: a brief overview

    Science.gov (United States)

    Terzioglu, Fatma; Kuchment, Peter; Kunyansky, Leonid

    2018-05-01

    While most of Radon transform applications to imaging involve integrations over smooth sub-manifolds of the ambient space, lately important situations have appeared where the integration surfaces are conical. Three of such applications are single scatter optical tomography, Compton camera medical imaging, and homeland security. In spite of the similar surfaces of integration, the data and the inverse problems associated with these modalities differ significantly. In this article, we present a brief overview of the mathematics arising in Compton camera imaging. In particular, the emphasis is made on the overdetermined data and flexible geometry of the detectors. For the detailed results, as well as other approaches (e.g. smaller-dimensional data or restricted geometry of detectors) the reader is directed to the relevant publications. Only a brief description and some references are provided for the single scatter optical tomography. This work was supported in part by NSF DMS grants 1211463 (the first two authors), 1211521 and 141877 (the third author), as well as a College of Science of Texas A&M University grant.

  8. Determination of the X-ray mass absorption coefficient by measurement of the intensity of AgKα Compton scattered radiation

    International Nuclear Information System (INIS)

    Franzini, M.; Leoni, L.; Saitta, M.

    1976-01-01

    By utilizing a reflection geometry, an accurate mass absorption coefficient of a sample can be determined by measuring the Ag Kα Compton intensity. Intensities of Ag Kα Compton scattered radiation have been collected by using either the usual reflection geometry of a Philips PW 1450 automatic x-ray spectrometer or a more refined reflection geometry, achieved on a Philips PW 1540/10A manual x-ray spectrometer. The experimental results have shown that the relationship between the Ag Kα Compton intensity and the mass absorption is a logarithmic function. The experimental results are not in agreement with those reported in literature, but a theoretical explanation to account for this fact has not been achieved as yet. (author)

  9. Stability analysis and time-step limits for a Monte Carlo Compton-scattering method

    International Nuclear Information System (INIS)

    Densmore, Jeffery D.; Warsa, James S.; Lowrie, Robert B.

    2010-01-01

    A Monte Carlo method for simulating Compton scattering in high energy density applications has been presented that models the photon-electron collision kinematics exactly [E. Canfield, W.M. Howard, E.P. Liang, Inverse Comptonization by one-dimensional relativistic electrons, Astrophys. J. 323 (1987) 565]. However, implementing this technique typically requires an explicit evaluation of the material temperature, which can lead to unstable and oscillatory solutions. In this paper, we perform a stability analysis of this Monte Carlo method and develop two time-step limits that avoid undesirable behavior. The first time-step limit prevents instabilities, while the second, more restrictive time-step limit avoids both instabilities and nonphysical oscillations. With a set of numerical examples, we demonstrate the efficacy of these time-step limits.

  10. A Compton suppressed detector multiplicity trigger based digital DAQ for gamma-ray spectroscopy

    Science.gov (United States)

    Das, S.; Samanta, S.; Banik, R.; Bhattacharjee, R.; Basu, K.; Raut, R.; Ghugre, S. S.; Sinha, A. K.; Bhattacharya, S.; Imran, S.; Mukherjee, G.; Bhattacharyya, S.; Goswami, A.; Palit, R.; Tan, H.

    2018-06-01

    The development of a digitizer based pulse processing and data acquisition system for γ-ray spectroscopy with large detector arrays is presented. The system is based on 250 MHz 12-bit digitizers, and is triggered by a user chosen multiplicity of Compton suppressed detectors. The logic for trigger generation is similar to the one practised for analog (NIM/CAMAC) pulse processing electronics, while retaining the fast processing merits of the digitizer system. Codes for reduction of data acquired from the system have also been developed. The system has been tested with offline studies using radioactive sources as well as in the in-beam experiments with an array of Compton suppressed Clover detectors. The results obtained therefrom validate its use in spectroscopic efforts for nuclear structure investigations.

  11. Deeply Virtual Compton Scattering off a deuterium target at the HERMES experiment

    International Nuclear Information System (INIS)

    Movsisyan, Aram

    2011-05-01

    Deeply virtual Compton scattering is studied in this report, using all data collected at the HERMES experiment from 1996 to 2005. Azimuthal asymmetries with respect to beam-helicity, beam-charge and target polarization alone and also to their different combinations for hard exclusive electroproduction of real photons in deep-inelastic scattering from a both unpolarized and longitudinally polarized deuterium targets are measured. The asymmetries are attributed to the interference between the deeply virtual Compton scattering and Bethe-Heitler processes. The asymmetries are observed in the exclusive region -(1.5) 2 GeV 2 2 X 2 GeV 2 of the squared missing mass. The dependences of these asymmetries on -t, x N , or Q 2 are investigated. The results include the coherent process ed→edγ and the incoherent process ed→epnγ where in addition a nucleon may be excited to a resonance. For an unpolarized deuterium target, the leading Fourier amplitude of the beam-helicity asymmetry that is sensitive to the interference term is found to be substantial, but no significant t dependence is observed. The leading amplitude of the beam-charge asymmetry is substantial at large -t, but becomes small at small values of -t. The amplitudes of the beam-helicity asymmetry that are sensitive to the squared DVCS term are found to be consistent with zero. The deuteron Compton form factor H 1 appears to have a similar behavior as H of the proton. (orig.)

  12. Development of a liquid xenon Compton telescope dedicated to functional medical imaging

    International Nuclear Information System (INIS)

    Grignon, C.

    2007-12-01

    Functional imaging is a technique used to locate in three dimensions the position of a radiotracer previously injected in a patient. The two main modalities used for a clinical application to detect tumors, the SPECT and the PET, use solid scintillators as a detection medium. The objective of this thesis was to investigate the possibility of using liquid xenon in order to benefit from the intrinsic properties of this medium in functional imaging. The feasibility study of such a device has been performed by taking into account the technical difficulties specific to the liquid xenon. First of all, simulations of a liquid xenon PET has been performed using Monte-Carlo methods. The results obtained with a large liquid xenon volume are promising : we can expect a reduction of the injected activity of radiotracer, an improvement of the spatial resolution of the image and a parallax free camera. The second part of the thesis was focused on the development of a new concept of medical imaging, the three gamma imaging, based on the use of a new emitter: the 44 scandium. Associated to a classical PET camera, the Compton telescope is used to infer the incoming direction of the third gamma ray by triangulation. Therefore, it is possible to reconstruct the position of each emitter in three dimensions. This work convinced the scientific community to support the construction and characterization of a liquid xenon Compton telescope. The first camera dedicated to small animal imaging should then be operational in 2009. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    Esmaeili-sani, Vahid, E-mail: vaheed_esmaeely80@yahoo.com [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of); Moussavi-zarandi, Ali; Boghrati, Behzad; Afarideh, Hossein [Department of Nuclear Engineering and Physics, Amirkabir University of Technology, P.O. Box 4155-4494, Tehran (Iran, Islamic Republic of)

    2012-02-01

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

  14. Charge dependence of the ratio of double to total ionization of a helium-like ion by Compton scattering of a high energy photon

    International Nuclear Information System (INIS)

    Suric, T.; Pisk, K.; Pratt, R.H.

    1996-01-01

    We examine the charge (Z) dependence of the nonrelativistic high energy limit for the double to total ionization ratio by Compton scattering of a photon, as well as by the photoeffect, utilizing our approach based on the impulse approximation or on the generalized shake-off theory. For all Z our high energy Compton ratio is about half the corresponding photoeffect ratio, calculated using the same assumptions or, alternatively, the ratio of double ionization by Compton scattering to double ionization by the photoeffect is about half the ratio for single ionization. We conclude that all current Compton calculations are consistent with this result, and we show that the recent calculation of Amusia and Mikhailov [Phys. Lett. A 199 (1995) 209] corresponds to our high Z results. (orig.)

  15. Influence of light curing unit and ceramic thickness on temperature rise during resin cement photo-activation.

    Science.gov (United States)

    Guiraldo, Ricardo Danil; Consani, Simonides; Mastrofrancisco, Sarina; Consani, Rafael Leonardo Xediek; Sinhoreti, Mario Alexandre Coelho; Correr-Sobrinho, Lourenço

    2008-11-01

    The aim of this study was to determine the effect of different ceramic thickness on heat generation during resin cement photo-activation by QTH (quartz-tungsten-halogen), LED (light emitting diode), and PAC (plasma arc-curing) LCUs (light curing units). The resin cement used was Rely X ARC (3M-ESPE), and the ceramic was IPS Empress Esthetic (Ivoclar-Vivadent), of which 0.7-, 1.4- and 2.0-mm thick disks, 0.8 mm in diameter were made. Temperature increase was recorded with a type-K thermocouple connected to a digital thermometer (Iopetherm 46). An acrylic resin base was built to guide the thermocouple and support the 1.0-mm thick dentin disk. A 0.1-mm thick black adhesive paper matrix with a perforation 6 mm in diameter was placed on the dentin to contain the resin cement and support the ceramic disks of different thicknesses. Three LCUs were used: QTH, LED and PAC. Nine groups were formed (n=10) according to the interaction: 3 ceramic thicknesses, 1 resin cement and 3 photo-activation methods. Temperature increase data were submitted to Tukey's test (5%). For all ceramic thicknesses, a statistically significant difference in temperature increase was observed among the LCUs, with the highest mean value for the QTH LCU (p0.05). The interaction of higher energy density with smaller ceramic thickness showed higher temperature increase values.

  16. A Green Fabry-Perot Cavity for Jefferson Lab Hall A Compton Polarimetry

    International Nuclear Information System (INIS)

    Rakhman, Abdurahim; Souder, Paul; Nanda, Sirish

    2009-01-01

    A green laser (CW, 532 nm) based Fabry-Perot cavity for high precision Compton Polarimetry is under development in Hall A of the Jefferson Laboratory. In this paper, we present the principle and the preliminary studies for our test cavity.

  17. Designing scheme of a γ-ray ICT system using compton back-scattering

    International Nuclear Information System (INIS)

    Xiao Jianmin

    1998-01-01

    The designing scheme of a γ ray ICT system by using Compton back-scattering is put forward. The technical norms, detector system, γ radioactive source, mechanical scanning equipment, and data acquisition and image reconstruction principle of this ICT are described

  18. Beam dynamics in Compton ring gamma sources

    Directory of Open Access Journals (Sweden)

    Eugene Bulyak

    2006-09-01

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

  19. Compton profiles by inelastic ion-electron scattering

    International Nuclear Information System (INIS)

    Boeckl, H.; Bell, F.

    1983-01-01

    It is shown that Compton profiles (CP) can be measured by inelastic ion-electron scattering. Within the impulse approximation the binary-encounter peak (BEP) reflects the CP of the target atom whereas the electron-loss peak (ELP) is given by projectile CP's. Evaluation of experimental data reveals that inelastic ion-electron scattering might be a promising method to supply inelastic electron or photon scattering for the determination of target CP's. The measurement of projectile CP's is unique to ion scattering since one gains knowledge about wave-function effects because of the high excitation degree of fast heavy-ion projectiles

  20. Development of a hard x-ray focal plane compton polarimeter: a compact polarimetric configuration with scintillators and Si photomultipliers

    Science.gov (United States)

    Chattopadhyay, T.; Vadawale, S. V.; Goyal, S. K.; Mithun, N. P. S.; Patel, A. R.; Shukla, R.; Ladiya, T.; Shanmugam, M.; Patel, V. R.; Ubale, G. P.

    2016-02-01

    X-ray polarization measurement of cosmic sources provides two unique parameters namely degree and angle of polarization which can probe the emission mechanism and geometry at close vicinity of the compact objects. Specifically, the hard X-ray polarimetry is more rewarding because the sources are expected to be intrinsically highly polarized at higher energies. With the successful implementation of Hard X-ray optics in NuSTAR, it is now feasible to conceive Compton polarimeters as focal plane detectors. Such a configuration is likely to provide sensitive polarization measurements in hard X-rays with a broad energy band. We are developing a focal plane hard X-ray Compton polarimeter consisting of a plastic scintillator as active scatterer surrounded by a cylindrical array of CsI(Tl) scintillators. The scatterer is 5 mm diameter and 100 mm long plastic scintillator (BC404) viewed by normal PMT. The photons scattered by the plastic scatterer are collected by a cylindrical array of 16 CsI(Tl) scintillators (5 mm × 5 mm × 150 mm) which are read by Si Photomultiplier (SiPM). Use of the new generation SiPMs ensures the compactness of the instrument which is essential for the design of focal plane detectors. The expected sensitivity of such polarimetric configuration and complete characterization of the plastic scatterer, specially at lower energies have been discussed in [11, 13]. In this paper, we characterize the CsI(Tl) absorbers coupled to SiPM. We also present the experimental results from the fully assembled configuration of the Compton polarimeter.

  1. Status of Kharkov X-ray Generator based on Compton Scattering NESTOR

    NARCIS (Netherlands)

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

    2004-01-01

    Nowadays the sources of the X-rays based on a storage ring with low beam energy and Compton scattering of intense laser beam are under development in several laboratories. In the paper the state-of-art in development and construction of cooperative project of a Kharkov advanced X-ray source NESTOR

  2. NADPH oxidase 4-derived superoxide mediates flow-stimulated NKCC2 activity in thick ascending limbs.

    Science.gov (United States)

    Saez, Fara; Hong, Nancy J; Garvin, Jeffrey L

    2018-05-01

    Luminal flow augments Na + reabsorption in the thick ascending limb more than can be explained by increased ion delivery. This segment reabsorbs 30% of the filtered load of Na + , playing a key role in its homeostasis. Whether flow elevations enhance Na + -K + -2Cl - cotransporter (NKCC2) activity and the second messenger involved are unknown. We hypothesized that raising luminal flow augments NKCC2 activity by enhancing superoxide ([Formula: see text]) production by NADPH oxidase 4 (NOX4). NKCC2 activity was measured in thick ascending limbs perfused at either 5 or 20 nl/min with and without inhibitors of [Formula: see text] production. Raising luminal flow from 5 to 20 nl/min enhanced NKCC2 activity from 4.8 ± 0.9 to 6.3 ± 1.2 arbitrary fluorescent units (AFU)/s. Maintaining flow at 5 nl/min did not alter NKCC2 activity. The superoxide dismutase mimetic manganese (III) tetrakis (4-benzoic acid) porphyrin chloride blunted NKCC2 activity from 3.5 ± 0.4 to 2.5 ± 0.2 AFU/s when flow was 20 nl/min but not 5 nl/min. When flow was 20 nl/min, NKCC2 activity showed no change with time. The selective NOX1/4 inhibitor GKT-137831 blunted NKCC2 activity when thick ascending limbs were perfused at 20 nl/min from 7.2 ± 1.1 to 4.5 ± 0.8 AFU/s but not at 5 nl/min. The inhibitor also prevented luminal flow from elevating [Formula: see text] production. Allopurinol, a xanthine oxidase inhibitor, had no effect on NKCC2 activity when flow was 20 nl/min. Tetanus toxin prevents flow-induced stimulation of NKCC2 activity. We conclude that elevations in luminal flow enhance NaCl reabsorption in thick ascending limbs by stimulating NKCC2 via NOX4 activation and increased [Formula: see text]. NKCC2 activation is primarily the result of insertion of new transporters in the membrane.

  3. A Ge(Li)-NaI(Tl) Compton-suppression spectrometer for in-beam γ-ray spectroscopy, ch. 2

    International Nuclear Information System (INIS)

    Driel, M.A. van; Hoogenboom, A.M.

    1976-01-01

    A Compton-suppression spectrometer has been constructed for in-beam γ-ray work. It consists of a closed-end Ge(Li) detector with an efficiency of 21% and a resolution of 2.0 keV for 1.33 MeV γ-rays surrounded by a NaI(Tl) shield (dia. 230 mm, length 280 mm). The overall Compton-suppression factor for a 60 Co spectrum is 10. Details of the construction are discussed and experimental properties are compared with design calculations

  4. A portable Compton spectrometer for clinical X-ray beams in the energy range 20-150 keV

    International Nuclear Information System (INIS)

    Vieira, A.A.; Linke, A.; Yoshimura, E.M.; Terini, R.A.; Herdade, S.B.

    2011-01-01

    Primary beam spectra were obtained for an X-ray industrial equipment (40-150 kV), and for a clinical mammography apparatus (25-35 kV) from beams scattered at angles close to 90 o , measured with a CdTe Compton spectrometer. Actual scattering angles were determined from the Compton energy shift of characteristic X-rays or spectra end-point energy. Evaluated contribution of coherent scattering amounts to more than 15% of fluence in mammographic beams. This technique can be used in clinical environments.

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

    Energy Technology Data Exchange (ETDEWEB)

    Trainham, R., E-mail: trainhcp@nv.doe.gov; Tinsley, J. [Special Technologies Laboratory of National Security Technologies, LLC, 5520 Ekwill Street, Santa Barbara, California 93111 (United States)

    2014-06-15

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

  6. EXTERNAL COMPTON SCATTERING IN BLAZAR JETS AND THE LOCATION OF THE GAMMA-RAY EMITTING REGION

    Energy Technology Data Exchange (ETDEWEB)

    Finke, Justin D., E-mail: justin.finke@nrl.navy.mil [U.S. Naval Research Laboratory, Code 7653, 4555 Overlook Ave. SW, Washington, DC, 20375-5352 (United States)

    2016-10-20

    I study the location of the γ -ray emission in blazar jets by creating a Compton-scattering approximation that is valid for all anisotropic radiation fields in the Thomson through Klein–Nishina regimes, is highly accurate, and can speed up numerical calculations by up to a factor of ∼10. I apply this approximation to synchrotron self-Compton, external Compton scattering of photons from the accretion disk, broad line region (BLR), and dust torus. I use a stratified BLR model and include detailed Compton-scattering calculations of a spherical and flattened BLR. I create two dust torus models, one where the torus is an annulus and one where it is an extended disk. I present detailed calculations of the photoabsorption optical depth using my detailed BLR and dust torus models, including the full angle dependence. I apply these calculations to the emission from a relativistically moving blob traveling through these radiation fields. The ratio of γ -ray to optical flux produces a predictable pattern that could help locate the γ -ray emission region. I show that the bright flare from 3C 454.3 in 2010 November detected by the Fermi Large Area Telescope is unlikely to originate from a single blob inside the BLR. This is because it moves outside the BLR in a time shorter than the flare duration, although emission by multiple blobs inside the BLR is possible. Also, γ -rays are unlikely to originate from outside of the BLR, due to the scattering of photons from an extended dust torus, since the cooling timescale would be too long to explain the observed short variability.

  7. Deeply virtual Compton scattering: How to test handbag dominance?

    International Nuclear Information System (INIS)

    Gousset, T.; Gousset, T.; Diehl, M.; Pire, B.; Diehl, M.; Ralston, J.P.

    1998-01-01

    We propose detailed tests of the handbag approximation in exclusive deeply virtual Compton scattering. Those tests make no use of any prejudice about parton correlations in the proton which are basically unknown objects and beyond the scope of perturbative QCD. Since important information on the proton substructure can be gained in the regime of light cone dominance we consider that such a class of tests is of special relevance. copyright 1998 American Institute of Physics

  8. Study of a high finesse four mirrors Fabry Perot cavity for X-rays and Gamma rays production by laser-electron Compton scattering

    International Nuclear Information System (INIS)

    Fedala, Y.

    2008-10-01

    The main goal of this thesis is the study and design of a high finesse Fabry Perot cavity to amplify a laser beam in order to achieve power gains ranging from 10 4 to 10 5 . This cavity is dedicated to the production of intense and monochromatic X-ray for medical applications (medical RADIOTHOMX ring) and gamma rays for a Compton based polarized positron source by Compton scattering of a high power laser beam and electron beam. To increase the brightness of the Compton interaction at the collision points, it is essential to have not only a high power laser beam but also very small laser beam radii at the interaction points. To achieve such performances, 2 scenarios are possible: a concentric 2 mirrors cavity which is mechanically unstable or a 4 mirrors cavity more complex but more stable. We tested numerically mechanical stability and stability of Eigen modes polarization of various planar and non-planar geometries of 4 mirrors cavities. Experimentally, we have developed a four mirrors tetrahedral 'bow-tie' cavity; radii of the order of 20 microns were made. The Eigen modes of such a cavity, in both planar and non planar geometries, were measured and compared with the numerical results. A good agreement was observed. In a second time, the impact of Compton interaction on the transverse dynamics, in the case of the polarized positrons source, and the longitudinal dynamic, in the case of the medical ring of the electron beam was studied. Compton scattering causes energy loss and induces an additional dispersion of energy in electron beam. For the polarized positrons source, 10 collision points are planned. The transport line has been determined and the modelling of the Compton interaction effect with a simple matrix calculation was made. For the medical ring, Compton scattering causes bunch lengthening and the increase of energy dispersion which are to influence the produced X-ray flux. A study of the longitudinal dynamics of the electron beam in the ring was

  9. Gamma ray polarimetry using a position sensitive germanium detector

    CERN Document Server

    Kroeger, R A; Kurfess, J D; Phlips, B F

    1999-01-01

    Imaging gamma-ray detectors make sensitive polarimeters in the Compton energy regime by measuring the scatter direction of gamma rays. The principle is to capitalize on the angular dependence of the Compton scattering cross section to polarized gamma rays and measure the distribution of scatter directions within the detector. This technique is effective in a double-sided germanium detector between roughly 50 keV and 1 MeV. This paper reviews device characteristics important to the optimization of a Compton polarimeter, and summarizes measurements we have made using a device with a 5x5 cm active area, 1 cm thickness, and strip-electrodes on a 2 mm pitch.

  10. Sum rules across the unpolarized Compton processes involving generalized polarizabilities and moments of nucleon structure functions

    Science.gov (United States)

    Lensky, Vadim; Hagelstein, Franziska; Pascalutsa, Vladimir; Vanderhaeghen, Marc

    2018-04-01

    We derive two new sum rules for the unpolarized doubly virtual Compton scattering process on a nucleon, which establish novel low-Q2 relations involving the nucleon's generalized polarizabilities and moments of the nucleon's unpolarized structure functions F1(x ,Q2) and F2(x ,Q2). These relations facilitate the determination of some structure constants which can only be accessed in off-forward doubly virtual Compton scattering, not experimentally accessible at present. We perform an empirical determination for the proton and compare our results with a next-to-leading-order chiral perturbation theory prediction. We also show how these relations may be useful for a model-independent determination of the low-Q2 subtraction function in the Compton amplitude, which enters the two-photon-exchange contribution to the Lamb shift of (muonic) hydrogen. An explicit calculation of the Δ (1232 )-resonance contribution to the muonic-hydrogen 2 P -2 S Lamb shift yields -1 ±1 μ eV , confirming the previously conjectured smallness of this effect.

  11. Deeply Virtual Compton Scattering off a deuterium target at the HERMES experiment

    Energy Technology Data Exchange (ETDEWEB)

    Movsisyan, Aram

    2011-05-15

    Deeply virtual Compton scattering is studied in this report, using all data collected at the HERMES experiment from 1996 to 2005. Azimuthal asymmetries with respect to beam-helicity, beam-charge and target polarization alone and also to their different combinations for hard exclusive electroproduction of real photons in deep-inelastic scattering from a both unpolarized and longitudinally polarized deuterium targets are measured. The asymmetries are attributed to the interference between the deeply virtual Compton scattering and Bethe-Heitler processes. The asymmetries are observed in the exclusive region -(1.5){sup 2} GeV{sup 2}Compton form factor H{sub 1} appears to have a similar behavior as H of the proton. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

    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

    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.

  13. Gravitation and Special Relativity from Compton Wave Interactions at the Planck Scale: An Algorithmic Approach

    Science.gov (United States)

    Blackwell, William C., Jr.

    2004-01-01

    In this paper space is modeled as a lattice of Compton wave oscillators (CWOs) of near- Planck size. It is shown that gravitation and special relativity emerge from the interaction between particles Compton waves. To develop this CWO model an algorithmic approach was taken, incorporating simple rules of interaction at the Planck-scale developed using well known physical laws. This technique naturally leads to Newton s law of gravitation and a new form of doubly special relativity. The model is in apparent agreement with the holographic principle, and it predicts a cutoff energy for ultrahigh-energy cosmic rays that is consistent with observational data.

  14. Development of a liquid xenon Compton telescope dedicated to functional medical imaging; Etude et developpement d'un telescope compton au xenon liquide dedie a l'imagerie medicale fonctionnelle

    Energy Technology Data Exchange (ETDEWEB)

    Grignon, C

    2007-12-15

    Functional imaging is a technique used to locate in three dimensions the position of a radiotracer previously injected in a patient. The two main modalities used for a clinical application to detect tumors, the SPECT and the PET, use solid scintillators as a detection medium. The objective of this thesis was to investigate the possibility of using liquid xenon in order to benefit from the intrinsic properties of this medium in functional imaging. The feasibility study of such a device has been performed by taking into account the technical difficulties specific to the liquid xenon. First of all, simulations of a liquid xenon PET has been performed using Monte-Carlo methods. The results obtained with a large liquid xenon volume are promising : we can expect a reduction of the injected activity of radiotracer, an improvement of the spatial resolution of the image and a parallax free camera. The second part of the thesis was focused on the development of a new concept of medical imaging, the three gamma imaging, based on the use of a new emitter: the 44 scandium. Associated to a classical PET camera, the Compton telescope is used to infer the incoming direction of the third gamma ray by triangulation. Therefore, it is possible to reconstruct the position of each emitter in three dimensions. This work convinced the scientific community to support the construction and characterization of a liquid xenon Compton telescope. The first camera dedicated to small animal imaging should then be operational in 2009. (author)

  15. First Compton telescope prototype based on continuous LaBr3-SiPM detectors

    International Nuclear Information System (INIS)

    Llosá, G.; Cabello, J.; Callier, S.; Gillam, J.E.; Lacasta, C.; Rafecas, M.; Raux, L.; Solaz, C.; Stankova, V.; La Taille, C. de; Trovato, M.; Barrio, J.

    2013-01-01

    A first prototype of a Compton camera based on continuous scintillator crystals coupled to silicon photomultiplier (SiPM) arrays has been successfully developed and operated. The prototype is made of two detector planes. The first detector is made of a continuous 16×18×5 mm 3 LaBr 3 crystal coupled to a 16-elements SiPM array. The elements have a size of 3×3 mm 3 in a 4.5×4.05 mm 2 pitch. The second detector, selected by availability, consists of a continuous 16×18×5 mm 3 LYSO crystal coupled to a similar SiPM array. The SPIROC1 ASIC is employed in the readout electronics. Data have been taken with a 22 Na source placed at different positions and images have been reconstructed with the simulated one-pass list-mode (SOPL) algorithm. Detector development for the construction of a second prototype with three detector planes is underway. LaBr 3 crystals of 32×36 mm 2 size and 5/10 mm thickness have been acquired and tested with a PMT. The resolution obtained is 3.5% FWHM at 511 keV. Each crystal will be coupled to four MPPC arrays. Different options are being tested for the prototype readout

  16. Asymmetry and the shift of the Compton profile

    International Nuclear Information System (INIS)

    Chatterjee, B.K.; Roy, S.C.; Suric, T.; LaJohn, L.A.; Pratt, R.H.

    2007-01-01

    We show that the conventionally defined asymmetry of the Compton profile (CP) is, to a large extent, simply a shift of CP. Compton scattering is widely used in studying the electron momentum distribution (EMD) of complex systems. Extraction of information about the EMD is based on an impulse approximation (IA) description of the process. In IA the scattering from bound electrons is described as scattering from the EMD of free electrons. Most often the angular and energy distributions of scattered photons (doubly differential cross sections (DDCS)) is measured and presented in terms of CP, which is just the DDCS normalized by a kinematical factor. The deviations of measured CP from the IA results are conventionally described as an asymmetry of CP about the IA peak position. IA predicts CP to be symmetric. We have examined the discrepancy between IA predictions (and the corresponding relativistic version of IA, RIA) and more rigorous approaches (A 2 and S-matrix), using independent particle approximations for the description of the bound state of electrons. In the nonrelativistic region (in which many measurements of CP are performed) we find that the conventional asymmetry can largely be understood as the shift of the peak position. The true asymmetry with respect to the shifted peak position is in fact much smaller. RIA has similar properties to IA, except that for atoms with high nuclear charge the p → .A → interaction may modify the shift and limit the utility of description as a shift

  17. Measurement of Deeply Virtual Compton Scattering at HERA

    CERN Document Server

    Adloff, C.; Andrieu, B.; Anthonis, T.; Arkadov, V.; Astvatsatourov, A.; Babaev, A.; Bahr, J.; Baranov, P.; Barrelet, E.; Bartel, W.; Bate, P.; Beglarian, A.; Behnke, O.; Beier, C.; Belousov, A.; Benisch, T.; Berger, Christoph; Berndt, T.; Bizot, J.C.; Boudry, V.; Braunschweig, W.; Brisson, V.; Broker, H.B.; Brown, D.P.; Bruckner, W.; Bruncko, D.; Burger, J.; Busser, F.W.; Bunyatyan, A.; Burrage, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Cao, Jun; Caron, S.; Clarke, D.; Clerbaux, B.; Collard, C.; Contreras, J.G.; Coppens, Y.R.; Coughlan, J.A.; Cousinou, M.C.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; Davidsson, M.; Delcourt, B.; Delerue, N.; Demirchyan, R.; De Roeck, A.; De Wolf, E.A.; Diaconu, C.; Dingfelder, J.; Dixon, P.; Dodonov, V.; Dowell, J.D.; Droutskoi, A.; Dubak, A.; Duprel, C.; Eckerlin, Guenter; Eckstein, D.; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Eisenhandler, E.; Ellerbrock, M.; Elsen, E.; Erdmann, M.; Erdmann, W.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Ferron, S.; Fleischer, M.; Fleming, Y.H.; Flugge, G.; Fomenko, A.; Foresti, I.; Formanek, J.; Foster, J.M.; Franke, G.; Gabathuler, E.; Gabathuler, K.; Garvey, J.; Gassner, J.; Gayler, Joerg; Gerhards, R.; Gerlich, C.; Ghazaryan, Samvel; Goerlich, L.; Gogitidze, N.; Goldberg, M.; Goodwin, C.; Grab, C.; Grassler, H.; Greenshaw, T.; Grindhammer, Guenter; Hadig, T.; Haidt, D.; Hajduk, L.; Haynes, W.J.; Heinemann, B.; Heinzelmann, G.; Henderson, R.C.W.; Hengstmann, S.; Henschel, H.; Heremans, R.; Herrera, G.; Herynek, I.; Hildebrandt, M.; Hilgers, M.; Hiller, K.H.; Hladky, J.; Hoting, P.; Hoffmann, D.; Horisberger, R.; Hurling, S.; Ibbotson, M.; Issever, C .; Jacquet, M.; Jaffre, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jones, M.A.S.; Jung, H.; Kastli, H.K.; Kant, D.; Kapichine, M.; Karlsson, M.; Karschnick, O.; Keil, F.; Keller, N.; Kennedy, J.; Kenyon, I.R.; Kermiche, S.; Kiesling, Christian M.; Kjellberg, P.; Klein, M.; Kleinwort, C.; Kluge, T.; Knies, G.; Koblitz, B.; Kolya, S.D.; Korbel, V.; Kostka, P.; Kotelnikov, S.K.; Koutouev, R.; Koutov, A.; Krehbiel, H.; Kroseberg, J.; Kruger, K.; Kupper, A.; Kuhr, T.; Kurca, T.; Lahmann, R.; Lamb, D.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Laycock, P.; Lebailly, E.; Lebedev, A.; Leissner, B.; Lemrani, R.; Lendermann, V.; Levonian, S.; Lindstroem, M.; List, B.; Lobodzinska, E.; Lobodzinski, B.; Loginov, A.; Loktionova, N.; Lubimov, V.; Luders, S.; Luke, D.; Lytkin, L.; Mahlke-Kruger, H.; Malden, N.; Malinovski, E.; Malinovski, I.; Maracek, R.; Marage, P.; Marks, J.; Marshall, R.; Martyn, H.U.; Martyniak, J.; Maxfield, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Meyer, P.O.; Mikocki, S.; Milstead, D.; Mkrtchyan, T.; Mohr, R.; Mohrdieck, S.; Mondragon, M.N.; Moreau, F.; Morozov, A.; Morris, J.V.; Muller, K.; Murin, P.; Nagovizin, V.; Naroska, B.; Naumann, J.; Naumann, T.; Nellen, G.; Newman, Paul R.; Nicholls, T.C.; Niebergall, F.; Niebuhr, C.; Nix, O.; Nowak, G.; Olsson, J.E.; Ozerov, D.; Panassik, V.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Phillips, J.P.; Pitzl, D.; Poschl, R.; Potachnikova, I.; Povh, B.; Rabbertz, K.; Radel, G.; Rauschenberger, J.; Reimer, P.; Reisert, B.; Reyna, D.; Risler, C.; Rizvi, E.; Robmann, P.; Roosen, R.; Rostovtsev, A.; Rusakov, S.; Rybicki, K.; Sankey, D.P.C.; Scheins, J.; Schilling, F.P.; Schleper, P.; Schmidt, D.; Schmidt, S.; Schmitt, S.; Schneider, M.; Schoeffel, L.; Schoning, A.; Schorner, T.; Schroder, V.; Schultz-Coulon, H.C.; Schwanenberger, C.; Sedlak, K.; Sefkow, F.; Chekelian, V.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Solovev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Spitzer, H.; Stamen, R.; Stella, B.; Stiewe, J.; Straumann, U.; Swart, M.; Tasevsky, M.; Chernyshov, V.; Chetchelnitski, S.; Thompson, Graham; Thompson, P.D.; Tobien, N.; Traynor, D.; Truoel, Peter; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Turney, J.E.; Tzamariudaki, E.; Udluft, S.; Urban, Marcel; Usik, A.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Vassilev, S.; Vazdik, Y.; Vichnevski, A.; Wacker, K.; Wallny, R.; Waugh, B.; Weber, G.; Weber, M.; Wegener, D.; Werner, C.; Werner, M.; Werner, N.; White, G.; Wiesand, S.; Wilksen, T.; Winde, M.; Winter, G.G.; Wissing, C.; Wobisch, M.; Wunsch, E.; Wyatt, A.C.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhokin, A.; Zomer, F.; Zsembery, J.; zur Nedden, M.

    2001-01-01

    A measurement is presented of elastic Deeply Virtual Compton Scattering e^+ + p -> e^+ + photon + p at HERA using data taken with the H1 detector. The cross section is measured as a function of the photon virtuality, Q^2, and the invariant mass, W, of the gamma p system, in the kinematic range 2 < Q^2 < 20 GeV^2, 30 < W < 120 GeV and |t| < 1 GeV^2, where t is the squared momentum transfer to the proton. The measurement is compared to QCD based calculations.

  18. Kharkov X-ray Generator Based On Compton Scattering

    International Nuclear Information System (INIS)

    Shcherbakov, A.; Zelinsky, A.; Mytsykov, A.; Gladkikh, P.; Karnaukhov, I.; Lapshin, V.; Telegin, Y.; Androsov, V.; Bulyak, E.; Botman, J.I.M.; Tatchyn, R.; Lebedev, A.

    2004-01-01

    Nowadays X-ray sources based on storage rings with low beam energy and Compton scattering of intense laser beams are under development in several laboratories. An international cooperative project of an advanced X-ray source of this type at the Kharkov Institute of Physics and Technology (KIPT) is described. The status of the project is reviewed. The design lattice of the storage ring and calculated X-ray beam parameters are presented. The results of numerical simulation carried out for proposed facility show a peak spectral X-ray intensity of about 1014 can be produced

  19. On the distribution of electrons in the double ionization of helium-like ions by Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Amusia, M Ya [Racah Institute of Physics, Hebrew University, Jerusalem 91904 (Israel); Drukarev, E G [Petersburg Nuclear Physics Institute, Gatchina, St Petersburg 188300 (Russian Federation)

    2003-06-28

    The Compton scattering of a high energy photon by a helium-like ion, followed by the ionization of two electrons, is considered outside of the Bethe surface of Compton scattering with the knock-out of a single electron. The role of shake-off (SO), of final state interactions (FSI) and of the quasi-free mechanism (QFM) is analysed. The triple and double differential distributions are calculated. It is demonstrated for the first time that in certain kinematical regions the process is dominated by the FSI and by the QFM, while the SO contribution is much smaller.

  20. Compton suppression tests on Ge and BGO prototype detectors for GAMMASPHERE

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, A M [Australian National Univ., Canberra, ACT (Australia); Khoo, T L; Bleich, M E; Carpenter, M P; Ahmad, I; Janssens, R V.F.; Moore, E F [Argonne National Lab., IL (United States); Bearden, I G [Purdue Univ., Lafayette, IN (United States); Beene, J R; Lee, I Y [Oak Ridge National Lab., TN (United States)

    1992-08-01

    In this paper, we report on measurements of the Compton suppression and overall P/T ratio of two Ge detectors in a BGO shield of the honeycomb pattern. These were the first prototype CSG detector assemblies for GAMMASPHERE. A more detailed description of these results will be published later. (author). 4 refs., 3 figs.

  1. Compton scattering of microwave background radiation by gas in galaxy clusters

    International Nuclear Information System (INIS)

    Gould, R.J.; Rephaeli, Y.

    1978-01-01

    Based on data on the X-ray spectrum of the Coma cluster, interpreted as thermal bremsstrahlung, the expected brightness depletion from Compton scattering of the microwave background in the direction of the cluster is computed. The calculated depletion is about one-third that recently observed by Gull and Northover, and the discrepancy is discussed. In comparing the observed microwave depletion in the direction of other clusters which are X-ray sources it is found that there is no correlation with the cluster X-ray luminosity, while a dependence proportional to L/sub x//sup 1/2/ is expected. Consequently, the microwave depletion observations cannot yet be taken as good evidence for a thermal bremsstrahlung origin for the X-ray emission. The perturbation from Compton scattering of photons on the high-frequency (Wien) tail of the blackbody distribution is computed and found to be much larger than predicted in previous calculations. In the Wien tail the effect is a relative increase in the blackbody intensity that is appreciably greater in magnitude than the depletion in the Rayleigh-Jeans domain

  2. A Compton polarimeter for CEBAF Hall A

    Energy Technology Data Exchange (ETDEWEB)

    Bardin, G; Cavata, C; Frois, B; Juillard, M; Kerhoas, S; Languillat, J C; Legoff, J M; Mangeot, P; Martino, J; Platchkov, S; Rebourgeard, P; Vernin, P; Veyssiere, C; CEBAF Hall A Collaboration

    1994-09-01

    The physic program at CEBAF Hall A includes several experiments using 4 GeV polarized electron beam: parity violation in electron elastic scattering from proton and {sup 4}He, electric form factor of the proton by recoil polarization, neutron spin structure function at low Q{sup 2}. Some of these experiments will need beam polarization measurement and monitoring with an accuracy close to 4%, for beam currents ranging from 100 nA to 100 microA. A project of a Compton Polarimeter that will meet these requirements is presented. It will comprise four dipoles and a symmetric cavity consisting of two identical mirrors. 1 fig., 10 refs.

  3. Cork quality estimation by using Compton tomography

    International Nuclear Information System (INIS)

    Brunetti, Antonio; Cesareo, Roberto; Golosio, Bruno; Luciano, Pietro; Ruggero, Alessandro

    2002-01-01

    The quality control of cork stoppers is mandatory in order to guarantee the perfect conservation of the wine. Several techniques have been developed but until now the quality control was essentially related to the status of the external surface. Thus possible cracks or holes inside the stopper will be hidden. In this paper a new technique based on X-ray Compton tomography is described. It is a non-destructive technique that allows one to reconstruct and visualize the cross-section of the cork stopper analyzed, and so to put in evidence the presence of internal imperfections. Some results are reported and compared with visual classification

  4. Cork quality estimation by using Compton tomography

    CERN Document Server

    Brunetti, A; Golosio, B; Luciano, P; Ruggero, A

    2002-01-01

    The quality control of cork stoppers is mandatory in order to guarantee the perfect conservation of the wine. Several techniques have been developed but until now the quality control was essentially related to the status of the external surface. Thus possible cracks or holes inside the stopper will be hidden. In this paper a new technique based on X-ray Compton tomography is described. It is a non-destructive technique that allows one to reconstruct and visualize the cross-section of the cork stopper analyzed, and so to put in evidence the presence of internal imperfections. Some results are reported and compared with visual classification.

  5. Development of an integrated response generator for Si/CdTe semiconductor Compton cameras

    International Nuclear Information System (INIS)

    Odaka, Hirokazu; Sugimoto, Soichiro; Ishikawa, Shin-nosuke; Katsuta, Junichiro; Koseki, Yuu; Fukuyama, Taro; Saito, Shinya; Sato, Rie; Sato, Goro; Watanabe, Shin

    2010-01-01

    We have developed an integrated response generator based on Monte Carlo simulation for Compton cameras composed of silicon (Si) and cadmium telluride (CdTe) semiconductor detectors. In order to construct an accurate detector response function, the simulation is required to include a comprehensive treatment of the semiconductor detector devices and the data processing system in addition to simulating particle tracking. Although CdTe is an excellent semiconductor material for detection of soft gamma rays, its ineffective charge transport property distorts its spectral response. We investigated the response of CdTe pad detectors in the simulation and present our initial results here. We also performed the full simulation of prototypes of Si/CdTe semiconductor Compton cameras and report on the reproducibility of detection efficiencies and angular resolutions of the cameras, both of which are essential performance parameters of astrophysical instruments.

  6. Cross section measurement and integral test for several activation reactions using T + d and thick-Li + d sources

    International Nuclear Information System (INIS)

    Dumais, J.R.; Tanaka, S.; Odano, N.; Iwasaki, S.; Sugiyama, K.

    1988-01-01

    Recent activities on the area of the cross section measurement for several activation reactions at Department of Nucl. Eng., Tohoku Univ. are described. The first subject is the cross section measurement for (n,2n) reaction on aluminum using the RTNS-II neutron source. Cross sections with rather small error band were obtained for the incident neutron energies from 14 to 14.7 MeV. The second one is the status of the program for the integral experiments on several reactions using the thick Li + d source at Tohoku Fast Neutron Lab. The experimental results showed the usefullness of the source as a tool for the cross section assessment. (author)

  7. Ice Thickness, Melting Rates and Styles of Activity in Ice-Volcano Interaction

    Science.gov (United States)

    Gudmundsson, M. T.

    2005-12-01

    In most cases when eruptions occur within glaciers they lead to rapid ice melting, jokulhlaups and/or lahars. Many parameters influence the style of activity and its impact on the environment. These include ice thickness (size of glacier), bedrock geometry, magma flow rate and magma composition. The eruptions that have been observed can roughly be divided into: (1) eruptions under several hundred meters thick ice on a relatively flat bedrock, (2) eruptions on flat or sloping bed through relatively thin ice, and (3) volcanism where effects are limitied to confinement of lava flows or melting of ice by pyroclastic flows or surges. This last category (ice-contact volcanism) need not cause much ice melting. Many of the deposits formed by Pleistocene volcanism in Iceland, British Columbia and Antarctica belong to the first category. An important difference between this type of activity and submarine activity (where pressure is hydrostatic) is that pressure at vents may in many cases be much lower than glaciostatic due to partial support of ice cover over vents by the surrounding glacier. Reduced pressure favours explosive activity. Thus the effusive/explosive transition may occur several hundred metres underneath the ice surface. Explosive fragmentation of magma leads to much higher rates of heat transfer than does effusive eruption of pillow lavas, and hence much higher melting rates. This effect of reduced pressure at vents will be less pronounced in a large ice sheet than in a smaller glacier or ice cap, since the hydraulic gradient that drives water away from an eruption site will be lower in the large glacier. This may have implications for form and type of eruption deposits and their relationship with ice thickness and glacier size.

  8. Design Study for Direction Variable Compton Scattering Gamma Ray

    Science.gov (United States)

    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

    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.

  9. Detection of inverse Compton scattering in plasma wakefield experiments

    Energy Technology Data Exchange (ETDEWEB)

    Bohlen, Simon

    2016-12-15

    Inverse Compton scattering (ICS) is the process of scattering of photons and electrons, where the photons gain a part of the electrons energy. In combination with plasma wakefield acceleration (PWA), ICS offers a compact MeV γ-ray source. A numerical study of ICS radiation produced in PWA experiments at FLASHForward was performed, using an ICS simulation code and the results from particle-in-cell modelling. The possibility of determining electron beam properties from measurements of the γ-ray source was explored for a wide range of experimental conditions. It was found that information about the electron divergence, the electron spectrum and longitudinal information can be obtained from measurements of the ICS beams for some cases. For the measurement of the ICS profile at FLASHForward, a CsI(Tl) scintillator array was chosen, similar to scintillators used in other ICS experiments. To find a suitable detector for spectrum measurements, an experimental test of a Compton spectrometer at the RAL was conducted. This test showed that a similar spectrometer could also be used at FLASHForward. However, changes to the spectrometer could be needed in order to use the pair production effect. In addition, further studies using Geant4 could lead to a better reconstruction of the obtained data. The studies presented here show that ICS is a promising method to analyse electron parameters from PWA experiments in further detail.

  10. Experimental test of Bell's inequalities using angular correlation of compton-scattered annihilation photons

    International Nuclear Information System (INIS)

    Osuch, S.; Popkiewicz, M.; Szeflinski, Z.; Wilhelmi, Z.

    1995-01-01

    The Bell's inequality has been experimentally tested using angular correlation of Compton-scattered photons from annihilation of positrons emitted from 22 Na source. The result shows a better agreement with the quantum mechanics predictions rather than with the Bell's inequality

  11. Determination of silicon in biological and botanical reference materials by epithermal INAA and Compton suppression

    International Nuclear Information System (INIS)

    Landsberger, S.; Peshev, S.; Becker, D.A.

    1994-01-01

    Silicon determination in sixteen botanical and biological standard reference materials is described using the 29 Si(n, p) 29 Al reaction through instrumental epithermal neutron activation analysis and Compton suppression gamma-ray spectroscopy. By simultaneous utilization of both cadmium and boron epithermal filters along with anticoincidence gamma-counting, detection limits as low as 12 ppm were obtained for certain matrices, much lower than previously reported values for this type of analysis. The method is applicable to many botanical and biological matrices and is attractive with its interference free, purely instrumental nature, compared with methods using the 28 Si(n, p) 28 Al reaction or chemical separation techniques. ((orig.))

  12. Optimization and verification of image reconstruction for a Compton camera towards application as an on-line monitor for particle therapy

    Science.gov (United States)

    Taya, T.; Kataoka, J.; Kishimoto, A.; Tagawa, L.; Mochizuki, S.; Toshito, T.; Kimura, M.; Nagao, Y.; Kurita, K.; Yamaguchi, M.; Kawachi, N.

    2017-07-01

    Particle therapy is an advanced cancer therapy that uses a feature known as the Bragg peak, in which particle beams suddenly lose their energy near the end of their range. The Bragg peak enables particle beams to damage tumors effectively. To achieve precise therapy, the demand for accurate and quantitative imaging of the beam irradiation region or dosage during therapy has increased. The most common method of particle range verification is imaging of annihilation gamma rays by positron emission tomography. Not only 511-keV gamma rays but also prompt gamma rays are generated during therapy; therefore, the Compton camera is expected to be used as an on-line monitor for particle therapy, as it can image these gamma rays in real time. Proton therapy, one of the most common particle therapies, uses a proton beam of approximately 200 MeV, which has a range of ~ 25 cm in water. As gamma rays are emitted along the path of the proton beam, quantitative evaluation of the reconstructed images of diffuse sources becomes crucial, but it is far from being fully developed for Compton camera imaging at present. In this study, we first quantitatively evaluated reconstructed Compton camera images of uniformly distributed diffuse sources, and then confirmed that our Compton camera obtained 3 %(1 σ) and 5 %(1 σ) uniformity for line and plane sources, respectively. Based on this quantitative study, we demonstrated on-line gamma imaging during proton irradiation. Through these studies, we show that the Compton camera is suitable for future use as an on-line monitor for particle therapy.

  13. Compton suppression method and epithermal NAA in the determination of nutrients and heavy metals in Nigerian food and beverages

    International Nuclear Information System (INIS)

    Ahmed, Y.A.; Landsberger, S.; O'Kelly, D.J.; Braisted, J.; Gabdo, H.; Ewa, I.O.B.; Umar, I.M.; Funtua, I.I.

    2010-01-01

    We used in this study Compton suppression method and epithermal neutron activation analysis to determine the concentration of nutrients and heavy metals in Nigerian food and beverages. The work was performed at the University of Texas TRIGA Reactor by short, medium, and long irradiation protocols, using thermal flux of 1.4x10 12 n cm -2 s -1 and epithermal flux of 1.4x10 11 n cm -2 s -1 . Application of Compton suppression method has reduced interferences from Compton scattered photons thereby allowing easy evaluation of Na, Cl, Ca, Cu, Mn, Mg, Co, Cr, Rb, Fe, and Se. The epithermal NAA method has enabled determination of Cd, As, Ba, Sr, Br, I, and V with little turn-around time. Quality Control and Quality Assurance of the method was tested by analyzing four Standard Reference Materials (non-fat powdered milk, apple leaves, citrus leaves, and peach leaves) obtained from National Institute for Standards and Technology. Our results show that sorghum, millet, and maize have high values of Zn, Mn, Fe, low values of Cd, As, and Se. Powdered milks, rice, beans, and soybeans were found to have moderate amounts of all the elements. Tobacco recorded high content of Cd, Mn, and As, whereas tea, tsobo leaves, Baobab leaves, and okro seed have more As values than others. However, biscuits, macaroni, spaghetti, and noodles show lower concentrations of all the elements. The distribution of these nutrients and heavy metals in these food and beverages shows the need to fortify biscuits and pastas with micro and macro-nutrients and reduce the use of tobacco, tea, tsobo leaves, Baobab leaves, and Okro seed to avoid intake of heavy elements.

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

    International Nuclear Information System (INIS)

    Fan, Yi-Zhong; Zhang, Fu-Wen; He, Hao-Ning; Zhou, Bei; Yang, Rui-Zhi; Jin, Zhi-Ping; Wei, Da-Ming; Tam, P. H. T.; Liang, Yun-Feng

    2013-01-01

    A nearby superluminous burst GRB 130427A was simultaneously detected by six γ-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 γ-ray energy release is ∼10 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 γ-rays at energies above 10 GeV, while five were detected in the same time interval. A possible unified model for the prompt soft γ-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

  15. AXIS: An instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF

    Energy Technology Data Exchange (ETDEWEB)

    Hall, G. N., E-mail: hall98@llnl.gov; Izumi, N.; Tommasini, R.; Carpenter, A. C.; Palmer, N. E.; Zacharias, R.; Felker, B.; Holder, J. P.; Allen, F. V.; Bell, P. M.; Bradley, D.; Montesanti, R.; Landen, O. L. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States)

    2014-11-15

    Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV–200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

  16. Application of Compton suppression spectrometry in the improvement of nuclear analytical techniques for biological samples

    International Nuclear Information System (INIS)

    Ahmed, Y. A.; Ewa, I.O.B.; Funtua, I.I.; Jonah, S.A.; Landsberger, S.

    2007-01-01

    Compton Suppression Factors (SF) and Compton Reduction Factors (RF) of the UT Austin's Compton suppression spectrometer being parameters characterizing the system performance were measured using ''1''3''7Cs and ''6''0Co point sources. The system performance was evaluated as a function of energy and geometry. The (P/C), A(P/C), (P/T), Cp, and Ce were obtained for each of the parameters. The natural background reduction factor in the anticoincidence mode and that of normal mode was calculated and its effect on the detection limit of biological samples evaluated. Applicability of the spectrometer and the method for biological samples was tested in the measurement of twenty-four elements (Ba, Sr, I, Br, Cu, V, Mg, Na, Cl, Mn, Ca, Sn, In, K, Mo, Cd, Zn, As, Sb, Ni, Rb, Cs, Fe, and Co) commonly found in food, milk, tea and tobacco items. They were determined from seven National Institute for Standard and Technology (NIST) certified reference materials (rice flour, oyster tissue, non-fat powdered milk, peach leaves, tomato leaves, apple leaves, and citrus leaves). Our results shows good agreement with the NIST certified values, indicating that the method developed in the present study is suitable for the determination of aforementioned elements in biological samples without undue interference problems

  17. AXIS: an instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF.

    Science.gov (United States)

    Hall, G N; Izumi, N; Tommasini, R; Carpenter, A C; Palmer, N E; Zacharias, R; Felker, B; Holder, J P; Allen, F V; Bell, P M; Bradley, D; Montesanti, R; Landen, O L

    2014-11-01

    Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV-200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

  18. Timelike Compton scattering off the neutron and generalized parton distributions

    Energy Technology Data Exchange (ETDEWEB)

    Boer, M.; Guidal, M. [CNRS-IN2P3, Universite Paris-Sud, Institut de Physique Nucleaire d' Orsay, Orsay (France); Vanderhaeghen, M. [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2016-02-15

    We study the exclusive photoproduction of an electron-positron pair on a neutron target in the Jefferson Lab energy domain. The reaction consists of two processes: the Bethe-Heitler and the Timelike Compton Scattering. The latter process provides potentially access to the Generalized Parton Distributions (GPDs) of the nucleon. We calculate all the unpolarized, single- and double-spin observables of the reaction and study their sensitivities to GPDs. (orig.)

  19. X-ray Compton scattering experiments for fluid alkali metals at high temperatures and pressures

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, K., E-mail: kazuhiro-matsuda@scphys.kyoto-u.ac.jp; Fukumaru, T.; Kimura, K.; Yao, M. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Tamura, K. [Graduate School of Engineering, Kyoto University, Kyoto 606-8502 (Japan); Katoh, M. [A.L.M.T. Corp., Iwasekoshi-Machi 2, Toyama 931-8543 (Japan); Kajihara, Y.; Inui, M. [Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521 (Japan); Itou, M.; Sakurai, Y. [Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

    2015-08-17

    We have developed a high-pressure vessel and a cell for x-ray Compton scattering measurements of fluid alkali metals. Measurements have been successfully carried out for alkali metal rubidium at elevated temperatures and pressures using synchrotron radiation at SPring-8. The width of Compton profiles (CPs) of fluid rubidium becomes narrow with decreasing fluid density, which indicates that the CPs sensitively detect the effect of reduction in the valence electron density. At the request of all authors of the paper, and with the agreement of the Proceedings Editor, an updated version of this article was published on 10 September 2015. The original article supplied to AIP Publishing was not the final version and contained PDF conversion errors in Formulas (1) and (2). The errors have been corrected in the updated and re-published article.

  20. Impact of active layer thickness of nitrogen-doped In–Sn–Zn–O films on materials and thin film transistor performances

    Science.gov (United States)

    Li, Zhi-Yue; Yang, Hao-Zhi; Chen, Sheng-Chi; Lu, Ying-Bo; Xin, Yan-Qing; Yang, Tian-Lin; Sun, Hui

    2018-05-01

    Nitrogen-doped indium tin zinc oxide (ITZO:N) thin film transistors (TFTs) were deposited on SiO2 (200 nm)/p-Si〈1 0 0〉 substrates by RF magnetron sputtering at room temperature. The structural, chemical compositions, surface morphology, optical and electrical properties as a function of the active layer thickness were investigated. As the active layer thickness increases, Zn content decreases and In content increases gradually. Meanwhile, Sn content is almost unchanged. When the thickness of the active layer is more than 45 nm, the ITZO:N films become crystallized and present a crystal orientation along InN(0 0 2) plan. No matter what the thickness is, ITZO:N films always display a high transmittance above 80% in the visible region. Their optical band gaps fluctuate between 3.4 eV and 3.62 eV. Due to the dominance of low interface trap density and high carrier concentration, ITZO:N TFT shows enhanced electrical properties as the active layer thickness is 35 nm. Its field-effect mobility, on/off radio and sub-threshold swing are 17.53 cm2 V‑1 · s‑1, 106 and 0.36 V/dec, respectively. These results indicate that the suitable thickness of the active layer can enhance the quality of ITZO:N films and decrease the defects density of ITZO:N TFT. Thus, the properties of ITZO:N TFT can be optimized by adjusting the thickness of the active layer.

  1. Determination of total iron in iron ore by x-ray fluorescence analysis using the Compton effect: comparison with others analytical techniques

    International Nuclear Information System (INIS)

    Castilho, M.V. de; Oliveira, R.C.

    1991-01-01

    Total iron in iron ores is determines by X-ray fluorescence analysis method using the compton effect. The Bragg angle is determined for compton no-coherent scattering related to K alpha of Rhodium. This measurement procedure can be used for best fitting of analytical results in X-ray fluorescence, when compared with others methods used for results corrections. (M.V.M.)

  2. Induced Compton scattering of a laser in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Liu, C.S.; Tripathi, V. K.

    2003-01-01

    A laser propagating through a high temperature low density plasma undergoes induced Compton backscattering involving the coupling of the laser pump and the scattered electromagnetic wave via the resonant electrons or the resistive quasimode. The region of nonlinear interaction is localized due to plasma inhomogeneity. At short density scale lengths when the interaction region is strongly localized and resonant electrons quickly move out of it, the electron distribution function remains Maxwellian and Compton reflectivity is significant at laser intensity >10 16 W/cm 2 . In gentle density gradients the resonant electrons are trapped in the ponderomotive and self-consistent potential well of the quasimode as they enter the interaction region. The ones with velocity v z p (v p being the phase velocity of the ponderomotive wave propagating along z direction) are accelerated to v p while those with v z >v p are retarded to v p . Since the number of the former is more than that of the latter there is a net momentum transfer to electrons. Momentum and action conservation lead to a reflectivity, R, that initially goes as the square of pump intensity, then rises gradually at higher intensity. R decreases rapidly with v th /v p , where v th is the thermal velocity of electrons

  3. Compton profiles of some 4d transition-metals

    International Nuclear Information System (INIS)

    Sharma, B.K.; Tomak, M.

    1982-08-01

    We have computed Compton profiles for 4d transition-metals using the Renormalized Free Atom (RFA) model for two different electron configurations, namely 4dsup(n-1)5s 1 and 4dsup(n-2)5s 2 . The results for niobium and molybdenum are presented and compared with those obtained for these metals within free atom model. For low values of momenta the RFA profiles are broader than the latter ones. The constancy of J(0) values reported for 3d-metals is shown to be present also in case of 4d-metals. (author)

  4. Passive amplification of a fiber laser in a Fabry-Perot cavity: application to gamma-ray production by Compton backscattering

    International Nuclear Information System (INIS)

    Labaye, F.

    2012-01-01

    One of the critical points of the International Linear Collider (ILC) is the polarized positrons source. Without going through further explanation on the physical process of polarized positrons production, we point out that they are produced when circularly polarized gamma rays interact with mater. Thus, the critical point is the circularly polarized gamma-ray source. A technical solution for this source is the Compton backscattering and in the end, this thesis takes place in the framework for the design of a high average power laser systems enslaved to Fabry-Perot cavities for polarized gamma-ray production by Compton backscattering. In the first part, we present this thesis context, the Compton backscattering principle and the choice for an optical architecture based on a fiber laser and a Fabry-Perot cavity. We finish by enumerating several possible applications for Compton backscattering which shows that the work presented here might benefits from technology transfer through others research fields. In the second part, we present the different fiber laser architecture studied as well as the results obtained. In the third part, we remind the operating principle of a Fabry-Perot cavity and present the one used for our experiment as well as its specificities. In the fourth part, we address the Compton backscattering experiment which enables us to present the joint utilization of a fiber laser and a Fabry-Perot cavity in a particles accelerator to generate gamma rays for the first time to our knowledge. This experiment took place in the Accelerator Test Facility (ATF). The experimental apparatus as well as the results obtained are thus presented. In the end, we summarize the results presented in this manuscript and propose different evolution possibilities for the system in a general conclusion. (author)

  5. Deuteron Compton scattering below pion photoproduction threshold

    Science.gov (United States)

    Levchuk, M. I.; L'vov, A. I.

    2000-07-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  6. Deuteron Compton scattering below pion photoproduction threshold

    International Nuclear Information System (INIS)

    Levchuk, M.I.; L'vov, A.I.

    2000-01-01

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data

  7. Deuteron Compton scattering below pion photoproduction threshold

    Energy Technology Data Exchange (ETDEWEB)

    Levchuk, M.I. E-mail: levchuk@dragon.bas-net.by; L' vov, A.I. E-mail: lvov@x4u.lebedev.ru

    2000-07-17

    Deuteron Compton scattering below pion photoproduction threshold is considered in the framework of the nonrelativistic diagrammatic approach with the Bonn OBE potential. A complete gauge-invariant set of diagrams is taken into account which includes resonance diagrams without and with NN-rescattering and diagrams with one- and two-body seagulls. The seagull operators are analyzed in detail, and their relations with free- and bound-nucleon polarizabilities are discussed. It is found that both dipole and higher-order polarizabilities of the nucleon are required for a quantitative description of recent experimental data. An estimate of the isospin-averaged dipole electromagnetic polarizabilities of the nucleon and the polarizabilities of the neutron is obtained from the data.

  8. Selenium content of Argentinean infant formulae and baby foods by pseudo-cyclic instrumental neutron activation analysis coupled to Compton suppression

    International Nuclear Information System (INIS)

    Hevia, S.; Chatt, A.

    2013-01-01

    The selenium levels of Argentinean infant formulae and baby food were measured using the 162-keV gamma-ray of 77m Se (t ½ = 17.4 s) by a pseudo-cyclic instrumental neutron activation analysis (PC-INAA) method in conjunction with Compton suppression spectrometry (CSS). For comparison purposes, 5 selected infant formulae were also analyzed for selenium by a radiochemical neutron activation analysis (RNAA) method. The selenium levels for three samples agreed between ±2.8 and 6.5 % while the other two differed by 12 and 17 % which could perhaps be attributed to sample inhomogeneity. The selenium content of cow milk-based infant formulae varied from 42-146 μg kg -1 compared to 52-63 μg kg -1 for soy-based milk formulae. In the case of baby foods, the selenium levels varied from 34 to 74 μg kg -1 . The detection limits for selenium by PC-INAA-CSS for all the samples analyzed in this work were between 8.5 and 65 μg kg -1 depending on the major elements present in the samples, while it was 20 μg kg -1 for the RNAA method. The expanded uncertainty (κ = 2) of the PC-INAA-CSS method was 7.0 % at the end of cycle 4 for a sample containing 73.7 μg kg -1 selenium compared to the RNAA value of 24.2 % for a sample of 67.0 μg kg -1 selenium content. (author)

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

    Science.gov (United States)

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

    2014-04-01

    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.

  10. NuSTAR SPECTROSCOPY OF MULTI-COMPONENT X-RAY REFLECTION FROM NGC 1068

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Franz E. [Pontificia Universidad Católica de Chile, Instituto de Astrofísica, Casilla 306, Santiago 22 (Chile); Arévalo, Patricia [EMBIGGEN Anillo, Concepción (Chile); Walton, Dominic J.; Baloković, Mislav; Brightman, Murray; Harrison, Fiona A. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States); Koss, Michael J. [Institute for Astronomy, Department of Physics, ETH Zurich, Wolfgang-Pauli-Strasse 27, CH-8093 Zurich (Switzerland); Puccetti, Simonetta [ASDC-ASI, Via del Politecnico, I-00133 Roma (Italy); Gandhi, Poshak [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Alexander, David M.; Moro, Agnese Del [Department of Physics, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Boggs, Steve E.; Craig, William W. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Brandt, William N.; Luo, Bin [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States); Christensen, Finn E. [DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby (Denmark); Comastri, Andrea [INAF-Osservatorio Astronomico di Bologna, via Ranzani 1, I-40127 Bologna (Italy); Hailey, Charles J. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Hickox, Ryan [Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, NH 03755 (United States); and others

    2015-10-20

    We report on high-energy X-ray observations of the Compton-thick Seyfert 2 galaxy NGC 1068 with NuSTAR, which provide the best constraints to date on its >10 keV spectral shape. The NuSTAR data are consistent with those from past and current instruments to within cross-calibration uncertainties, and we find no strong continuum or line variability over the past two decades, which is in line with its X-ray classification as a reflection-dominated Compton-thick active galactic nucleus. The combined NuSTAR, Chandra, XMM-Newton, and Swift BAT spectral data set offers new insights into the complex secondary emission seen instead of the completely obscured transmitted nuclear continuum. The critical combination of the high signal-to-noise NuSTAR data and the decomposition of the nuclear and extranuclear emission with Chandra allow us to break several model degeneracies and greatly aid physical interpretation. When modeled as a monolithic (i.e., a single N{sub H}) reflector, none of the common Compton reflection models are able to match the neutral fluorescence lines and broad spectral shape of the Compton reflection hump without requiring unrealistic physical parameters (e.g., large Fe overabundances, inconsistent viewing angles, or poor fits to the spatially resolved spectra). A multi-component reflector with three distinct column densities (e.g., with best-fit values of N{sub H} of 1.4 × 10{sup 23}, 5.0 × 10{sup 24}, and 10{sup 25} cm{sup −2}) provides a more reasonable fit to the spectral lines and Compton hump, with near-solar Fe abundances. In this model, the higher N{sub H} component provides the bulk of the flux to the Compton hump, while the lower N{sub H} component produces much of the line emission, effectively decoupling two key features of Compton reflection. We find that ≈30% of the neutral Fe Kα line flux arises from >2″ (≈140 pc) and is clearly extended, implying that a significant fraction (and perhaps most) of the <10 keV reflected component

  11. Detection of detachments and inhomogeneities in frescos by Compton scattering

    International Nuclear Information System (INIS)

    Castellano, A.; Cesareo, R.; Buccolieri, G.; Donativi, M.; Palama, F.; Quarta, S.; De Nunzio, G.; Brunetti, A.; Marabelli, M.; Santamaria, U.

    2005-01-01

    A mobile instrument has been developed for the detection and mapping of detachments in frescos by using Compton back scattered photons. The instrument is mainly composed of a high energy X-ray tube, an X-ray detection system and a translation table. The instrument was first applied to samples simulating various detachment situations, and then transferred to the Vatican Museum to detect detachments and inhomogeneities in the stanza di Eliodoro, one of the 'Raphael's stanze'

  12. High-energy electroweak neutrino-nucleon deeply virtual Compton scattering

    International Nuclear Information System (INIS)

    Machado, Magno V. T.

    2007-01-01

    In this work we estimate the differential and total cross sections for the high-energy deeply virtual Compton scattering in the weak sector. In the weak neutral sector one considers neutrino scattering off an unpolarized proton target through the exchange of Z 0 . We numerically compute the process Z*p→γp within the QCD color dipole formalism, which successfully describes the current high-energy electromagnetic DVCS experimental data. We also discuss possible applications for the weak charged sector and perform predictions for scattering on nuclear targets

  13. Measurement of the Proton Structure Function $F_{2}$ at low $Q^{2}$ in QED Compton Scattering at HERA

    CERN Document Server

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

    2004-01-01

    The proton structure function F_2(x,Q^2) is measured in inelastic QED Compton scattering using data collected with the H1 detector at HERA. QED Compton events are used to access the kinematic range of very low virtualities of the exchanged photon, Q^2, down to 0.5 GeV^2, and Bjorken x up to \\sim 0.06, a region which has not been covered previously by inclusive measurements at HERA. The results are in agreement with the measurements from fixed target lepton-nucleon scattering experiments.

  14. The description of compton lines in energy-dispersive x-ray Fluorescence

    International Nuclear Information System (INIS)

    Van Gysel, Mon; Van Espen, P.J.M.

    2001-01-01

    Energy-Dispersive X-Ray Fluorescence (ED-XRF) is a non-destructive technique for the element analysis in a concentration range ppm - % making use of X rays up to 100 keV. Generally, two photon matter interactions occur, respectively absorption and scattering. The absorption of incident photons gives raise to characteristic lines. Scattering gives an incoherent and a coherent line. A Gaussian peak model is adequate to describe the characteristic and coherent scattered lines. Incoherent lines appear as non-Gaussian, broadened peaks. The profile of a Compton peak is complex. It depends on the geometry and the composition of the sample. Especially, when analyzing a low Z matrix; dominant scattering and multiple scattering may cause large interferences. The absence of an appropriate fitting model makes the Compton profile seen as a limiting factor in the evaluation of spectra. An accurate description of incoherent lines should improve quantitative analysis. Therefore, a suitable fitting model, making use of the expertise of non-linear least squares procedures and Monte-Carlo calculations was systematically investigated. The proposed model, containing a modified Gaussian, is tested on experimental data recorded with a HPGe detector

  15. Inverse Compton gamma-rays from galactic dark matter annihilation. Anisotropy signatures

    International Nuclear Information System (INIS)

    Zhang, Le; Sigl, Guenter; Miniati, Francesco

    2010-08-01

    High energy electrons and positrons from annihilating dark matter can imprint unique angular anisotropies on the diffuse gamma-ray flux by inverse Compton scattering off the interstellar radiation field. We develop a numerical tool to compute gamma-ray emission from such electrons and positrons diffusing in the smooth host halo and in substructure halos with masses down to 10 -6 M s un. We show that, unlike the total gamma-ray angular power spectrum observed by Fermi-LAT, the angular power spectrum from inverse Compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons. For TeV scale dark matter with a canonical thermal freeze-out cross section 3 x 10 -26 cm 3 /s, this feature may be detectable by Fermi-LAT in the energy range 100-300 GeV after more sophisticated foreground subtraction. We also find that the total flux and the shape of the angular power spectrum depends sensitively on the spatial distribution of subhalos in the Milky Way. Finally, the contribution from the smooth host halo component to the gamma-ray mean intensity is negligibly small compared to subhalos. (orig.)

  16. Inverse Compton gamma-rays from galactic dark matter annihilation. Anisotropy signatures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Le; Sigl, Guenter [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Miniati, Francesco [ETH Zuerich (Switzerland). Physics Dept.

    2010-08-15

    High energy electrons and positrons from annihilating dark matter can imprint unique angular anisotropies on the diffuse gamma-ray flux by inverse Compton scattering off the interstellar radiation field. We develop a numerical tool to compute gamma-ray emission from such electrons and positrons diffusing in the smooth host halo and in substructure halos with masses down to 10{sup -6}M{sub s}un. We show that, unlike the total gamma-ray angular power spectrum observed by Fermi-LAT, the angular power spectrum from inverse Compton scattering is exponentially suppressed below an angular scale determined by the diffusion length of electrons and positrons. For TeV scale dark matter with a canonical thermal freeze-out cross section 3 x 10{sup -26} cm{sup 3}/s, this feature may be detectable by Fermi-LAT in the energy range 100-300 GeV after more sophisticated foreground subtraction. We also find that the total flux and the shape of the angular power spectrum depends sensitively on the spatial distribution of subhalos in the Milky Way. Finally, the contribution from the smooth host halo component to the gamma-ray mean intensity is negligibly small compared to subhalos. (orig.)

  17. A didactic experiment showing the Compton scattering by means of a clinical gamma camera.

    Science.gov (United States)

    Amato, Ernesto; Auditore, Lucrezia; Campennì, Alfredo; Minutoli, Fabio; Cucinotta, Mariapaola; Sindoni, Alessandro; Baldari, Sergio

    2017-06-01

    We describe a didactic approach aimed to explain the effect of Compton scattering in nuclear medicine imaging, exploiting the comparison of a didactic experiment with a gamma camera with the outcomes from a Monte Carlo simulation of the same experimental apparatus. We employed a 99m Tc source emitting 140.5keV photons, collimated in the upper direction through two pinholes, shielded by 6mm of lead. An aluminium cylinder was placed on the source at 50mm of distance. The energy of the scattered photons was measured on the spectra acquired by the gamma camera. We observed that the gamma ray energy measured at each step of rotation gradually decreased from the characteristic energy of 140.5keV at 0° to 102.5keV at 120°. A comparison between the obtained data and the expected results from the Compton formula and from the Monte Carlo simulation revealed a full agreement within the experimental error (relative errors between -0.56% and 1.19%), given by the energy resolution of the gamma camera. Also the electron rest mass has been evaluated satisfactorily. The experiment was found useful in explaining nuclear medicine residents the phenomenology of the Compton scattering and its importance in the nuclear medicine imaging, and it can be profitably proposed during the training of medical physics residents as well. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

  18. NuSTAR Observations of the Compton-Thick Active Galactic Nucleus and Ultraluminous X-Ray Source Candidate in NGC 5643

    DEFF Research Database (Denmark)

    Annuar, A.; Gandhi, P.; Alexander, D. M.

    2015-01-01

    We present two Nuclear Spectroscopic Telescope Array (NuSTAR) observations of the local Seyfert 2 active galactic nucleus (AGN) and an ultraluminous X-ray source (ULX) candidate in NGC 5643. Together with archival data from Chandra, XMM-Newton, and Swift-BAT, we perform a high-quality broadband s...

  19. Study on the Spatial Resolution of Single and Multiple Coincidences Compton Camera

    Science.gov (United States)

    Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

    2012-10-01

    In this paper we study the image resolution that can be obtained from the Multiple Coincidences Compton Camera (MCCC). The principle of MCCC is based on a simultaneous acquisition of several gamma-rays emitted in cascade from a single nucleus. Contrary to a standard Compton camera, MCCC can theoretically provide the exact location of a radioactive source (based only on the identification of the intersection point of three cones created by a single decay), without complicated tomographic reconstruction. However, practical implementation of the MCCC approach encounters several problems, such as low detection sensitivities result in very low probability of coincident triple gamma-ray detection, which is necessary for the source localization. It is also important to evaluate how the detection uncertainties (finite energy and spatial resolution) influence identification of the intersection of three cones, thus the resulting image quality. In this study we investigate how the spatial resolution of the reconstructed images using the triple-cone reconstruction (TCR) approach compares to images reconstructed from the same data using standard iterative method based on single-cone. Results show, that FWHM for the point source reconstructed with TCR was 20-30% higher than the one obtained from the standard iterative reconstruction based on expectation maximization (EM) algorithm and conventional single-cone Compton imaging. Finite energy and spatial resolutions of the MCCC detectors lead to errors in conical surfaces definitions (“thick” conical surfaces) which only amplify in image reconstruction when intersection of three cones is being sought. Our investigations show that, in spite of being conceptually appealing, the identification of triple cone intersection constitutes yet another restriction of the multiple coincidence approach which limits the image resolution that can be obtained with MCCC and TCR algorithm.

  20. Constant-q data representation in Neutron Compton scattering on the VESUVIO spectrometer

    International Nuclear Information System (INIS)

    Senesi, R.; Pietropaolo, A.; Andreani, C.

    2008-01-01

    Standard data analysis on the VESUVIO spectrometer at ISIS is carried out within the Impulse Approximation framework, making use of the West scaling variable y. The experiments are performed using the time-of-flight technique with the detectors positioned at constant scattering angles. Line shape analysis is routinely performed in the y-scaling framework, using two different (and equivalent) approaches: (1) fitting the parameters of the recoil peaks directly to fixed-angle time-of-flight spectra; (2) transforming the time-of-flight spectra into fixed-angle y spectra, referred to as the Neutron Compton Profiles, and then fitting the line shape parameters. The present work shows that scattering signals from different fixed-angle detectors can be collected and rebinned to obtain Neutron Compton Profiles at constant wave vector transfer, q, allowing for a suitable interpretation of data in terms of the dynamical structure factor, S(q,ω). The current limits of applicability of such a procedure are discussed in terms of the available q-range and relative uncertainties for the VESUVIO experimental set up and of the main approximations involved

  1. Constant-q data representation in Neutron Compton scattering on the VESUVIO spectrometer

    Energy Technology Data Exchange (ETDEWEB)

    Senesi, R. [Dipartimento di Fisica, Universita degli Studi di Roma ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Roma (Italy); Centro NAST, Nanoscienze and Nanotecnologie and Strumentazione, Universita degli Studi di Roma ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Roma (Italy)], E-mail: roberto.senesi@roma2.infn.it; Pietropaolo, A.; Andreani, C. [Dipartimento di Fisica, Universita degli Studi di Roma ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Roma (Italy); Centro NAST, Nanoscienze and Nanotecnologie and Strumentazione, Universita degli Studi di Roma ' Tor Vergata' , Via della Ricerca Scientifica 1, 00133 Roma (Italy)

    2008-09-01

    Standard data analysis on the VESUVIO spectrometer at ISIS is carried out within the Impulse Approximation framework, making use of the West scaling variable y. The experiments are performed using the time-of-flight technique with the detectors positioned at constant scattering angles. Line shape analysis is routinely performed in the y-scaling framework, using two different (and equivalent) approaches: (1) fitting the parameters of the recoil peaks directly to fixed-angle time-of-flight spectra; (2) transforming the time-of-flight spectra into fixed-angle y spectra, referred to as the Neutron Compton Profiles, and then fitting the line shape parameters. The present work shows that scattering signals from different fixed-angle detectors can be collected and rebinned to obtain Neutron Compton Profiles at constant wave vector transfer, q, allowing for a suitable interpretation of data in terms of the dynamical structure factor, S(q,{omega}). The current limits of applicability of such a procedure are discussed in terms of the available q-range and relative uncertainties for the VESUVIO experimental set up and of the main approximations involved.

  2. Constant- q data representation in Neutron Compton scattering on the VESUVIO spectrometer

    Science.gov (United States)

    Senesi, R.; Pietropaolo, A.; Andreani, C.

    2008-09-01

    Standard data analysis on the VESUVIO spectrometer at ISIS is carried out within the Impulse Approximation framework, making use of the West scaling variable y. The experiments are performed using the time-of-flight technique with the detectors positioned at constant scattering angles. Line shape analysis is routinely performed in the y-scaling framework, using two different (and equivalent) approaches: (1) fitting the parameters of the recoil peaks directly to fixed-angle time-of-flight spectra; (2) transforming the time-of-flight spectra into fixed-angle y spectra, referred to as the Neutron Compton Profiles, and then fitting the line shape parameters. The present work shows that scattering signals from different fixed-angle detectors can be collected and rebinned to obtain Neutron Compton Profiles at constant wave vector transfer, q, allowing for a suitable interpretation of data in terms of the dynamical structure factor, S(q,ω). The current limits of applicability of such a procedure are discussed in terms of the available q-range and relative uncertainties for the VESUVIO experimental set up and of the main approximations involved.

  3. Development of a sub-MeV X-ray source via Compton backscattering

    International Nuclear Information System (INIS)

    Kawase, K.; Kando, M.; Hayakawa, T.; Daito, I.; Kondo, S.; Homma, T.; Kameshima, T.; Kotaki, H.; Chen, L.-M.; Fukuda, Y.; Faenov, A.; Shizuma, T.; Shimomura, T.; Yoshida, H.; Hajima, R.; Fujiwara, M.; Bulanov, S.V.; Kimura, T.; Tajima, T.

    2011-01-01

    At the Kansai Photon Science Institute of the Japan Atomic Energy Agency, we have developed a Compton backscattered X-ray source in the energy region of a few hundred keV. The X-ray source consists of a 150-MeV electron beam, with a pulse duration of 10 ps (rms), accelerated by a Microtron accelerator and an Nd:YAG laser, with a pulse duration of 10 ns (FWHM). In the first trial experiment, the X-ray flux is estimated to be (2.2±1.0)x10 2 photons/pulse. For the actual application of an X-ray source, it is important to increase the generated X-ray flux as much as possible. Thus, for the purpose of increasing the X-ray flux, we have developed the pulse compression system for the Nd:YAG laser via stimulated Brillouin scattering (SBS). The SBS pulse compression has the great advantages of a high conversion efficiency and a simple structure. In this article, we review the present status of the Compton backscattered X-ray source and describe the SBS pulse compression system.

  4. Evaluation of geometrical contributions to the spread of the Compton-scatter energy distribution

    International Nuclear Information System (INIS)

    Hanson, A.L.; Gigante, G.E.; Dipartimento di Fisica, Universita degli Studi di Roma I, ''La Sapienza,'' Corso Vittorio Emanuele II, 244, 00186 Roma, Italy)

    1989-01-01

    The spectrum from Compton-scattered x rays is an inherently broad distribution. This distribution is the sum of several Gaussian-like distributions, which gives the sum its unique shape. The Gaussian-like distributions are the result of convoluting the so-called Compton profile, the spread in the scattered-x-ray energies due to the momentum distributions of the target electrons, with the detector response and the geometrical effects. The distribution is then further modified by the absorption within the sample. A formulation for both qualitatively and quantitatively determining the magnitude of the geometrical contributions is presented. This formulation is based on a recently devised approach to the scattering geometry [Hanson, Gigante, Meron, Phys. Rev. Lett. 61, 135 (1988)]. A methodology for determining the geometrical spread in the energy of the scattered x rays is presented. The results can be conveniently used to optimize scattering geometries for the reduction of the geometry-caused spread

  5. BOW TIES IN THE SKY. I. THE ANGULAR STRUCTURE OF INVERSE COMPTON GAMMA-RAY HALOS IN THE FERMI SKY

    Energy Technology Data Exchange (ETDEWEB)

    Broderick, Avery E.; Shalaby, Mohamad [Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, ON, N2L 3G1 (Canada); Tiede, Paul [Perimeter Institute for Theoretical Physics, 31 Caroline Street North, Waterloo, ON, N2L 2Y5 (Canada); Pfrommer, Christoph [Heidelberg Institute for Theoretical Studies, Schloss-Wolfsbrunnenweg 35, D-69118 Heidelberg (Germany); Puchwein, Ewald [Institute of Astronomy and Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge, CB3 0HA (United Kingdom); Chang, Philip [Department of Physics, University of Wisconsin-Milwaukee, 1900 E. Kenwood Boulevard, Milwaukee, WI 53211 (United States); Lamberts, Astrid [Theoretical Astrophysics, California Institute of Technology, Pasadena, CA 91125 (United States)

    2016-12-01

    Extended inverse Compton halos are generally anticipated around extragalactic sources of gamma rays with energies above 100 GeV. These result from inverse Compton scattered cosmic microwave background photons by a population of high-energy electron/positron pairs produced by the annihilation of the high-energy gamma rays on the infrared background. Despite the observed attenuation of the high-energy gamma rays, the halo emission has yet to be directly detected. Here, we demonstrate that in most cases these halos are expected to be highly anisotropic, distributing the upscattered gamma rays along axes defined either by the radio jets of the sources or oriented perpendicular to a global magnetic field. We present a pedagogical derivation of the angular structure in the inverse Compton halo and provide an analytic formalism that facilitates the generation of mock images. We discuss exploiting this fact for the purpose of detecting gamma-ray halos in a set of companion papers.

  6. Transmission characteristics of the kinematics of the laser-plasma shock wave in air in compton scattering

    International Nuclear Information System (INIS)

    Hao Dongshan; Xie Hongjun

    2006-01-01

    By comparing the kinematical equation of a shock wave in free air, the study of transmission characteristics of the laser plasma shock wave in Compton scattering is presented. The results show that the attenuation course of the kinematics of he laser plasma shock wave is related not only with the explosion fountainhead and the characteristics of the explosion course, total energy release, air elastic, but also with multi-photon nonlinear Compton scattering. Because of the scattering the initial radius of the shock wave increases, the attenuation course shortens, the energy metastasis efficiency rises. The results of the numerical analysis and the actual values of the shock waves in air by a way intense explosion are very tallying. (authors)

  7. Compton suppression method and epithermal NAA in the determination of nutrients and heavy metals in Nigerian food and beverages

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, Y.A., E-mail: yaahmed1@gmail.co [Reactor Engineering Section, Centre for Energy Research and Training, Ahmadu Bello University, Zaria (Nigeria); Nuclear Engineering Teaching Laboratory, University of Texas at Austin, Austin, TX 78758 (United States); Landsberger, S.; O' Kelly, D.J.; Braisted, J. [Nuclear Engineering Teaching Laboratory, University of Texas at Austin, Austin, TX 78758 (United States); Gabdo, H. [Physics Department, Federal College of Education, Yola (Nigeria); Ewa, I.O.B.; Umar, I.M.; Funtua, I.I. [Reactor Engineering Section, Centre for Energy Research and Training, Ahmadu Bello University, Zaria (Nigeria)

    2010-10-15

    We used in this study Compton suppression method and epithermal neutron activation analysis to determine the concentration of nutrients and heavy metals in Nigerian food and beverages. The work was performed at the University of Texas TRIGA Reactor by short, medium, and long irradiation protocols, using thermal flux of 1.4x10{sup 12} n cm{sup -2} s{sup -1} and epithermal flux of 1.4x10{sup 11} n cm{sup -2} s{sup -1}. Application of Compton suppression method has reduced interferences from Compton scattered photons thereby allowing easy evaluation of Na, Cl, Ca, Cu, Mn, Mg, Co, Cr, Rb, Fe, and Se. The epithermal NAA method has enabled determination of Cd, As, Ba, Sr, Br, I, and V with little turn-around time. Quality Control and Quality Assurance of the method was tested by analyzing four Standard Reference Materials (non-fat powdered milk, apple leaves, citrus leaves, and peach leaves) obtained from National Institute for Standards and Technology. Our results show that sorghum, millet, and maize have high values of Zn, Mn, Fe, low values of Cd, As, and Se. Powdered milks, rice, beans, and soybeans were found to have moderate amounts of all the elements. Tobacco recorded high content of Cd, Mn, and As, whereas tea, tsobo leaves, Baobab leaves, and okro seed have more As values than others. However, biscuits, macaroni, spaghetti, and noodles show lower concentrations of all the elements. The distribution of these nutrients and heavy metals in these food and beverages shows the need to fortify biscuits and pastas with micro and macro-nutrients and reduce the use of tobacco, tea, tsobo leaves, Baobab leaves, and Okro seed to avoid intake of heavy elements.

  8. Compton suppression method and epithermal NAA in the determination of nutrients and heavy metals in Nigerian food and beverages.

    Science.gov (United States)

    Ahmed, Y A; Landsberger, S; O'Kelly, D J; Braisted, J; Gabdo, H; Ewa, I O B; Umar, I M; Funtua, I I

    2010-10-01

    We used in this study Compton suppression method and epithermal neutron activation analysis to determine the concentration of nutrients and heavy metals in Nigerian food and beverages. The work was performed at the University of Texas TRIGA Reactor by short, medium, and long irradiation protocols, using thermal flux of 1.4x10(12)n cm(-2)s(-1) and epithermal flux of 1.4x10(11)n cm(-2)s(-1). Application of Compton suppression method has reduced interferences from Compton scattered photons thereby allowing easy evaluation of Na, Cl, Ca, Cu, Mn, Mg, Co, Cr, Rb, Fe, and Se. The epithermal NAA method has enabled determination of Cd, As, Ba, Sr, Br, I, and V with little turn-around time. Quality Control and Quality Assurance of the method was tested by analyzing four Standard Reference Materials (non-fat powdered milk, apple leaves, citrus leaves, and peach leaves) obtained from National Institute for Standards and Technology. Our results show that sorghum, millet, and maize have high values of Zn, Mn, Fe, low values of Cd, As, and Se. Powdered milks, rice, beans, and soybeans were found to have moderate amounts of all the elements. Tobacco recorded high content of Cd, Mn, and As, whereas tea, tsobo leaves, Baobab leaves, and okro seed have more As values than others. However, biscuits, macaroni, spaghetti, and noodles show lower concentrations of all the elements. The distribution of these nutrients and heavy metals in these food and beverages shows the need to fortify biscuits and pastas with micro and macro-nutrients and reduce the use of tobacco, tea, tsobo leaves, Baobab leaves, and Okro seed to avoid intake of heavy elements. Copyright 2010 Elsevier Ltd. All rights reserved.

  9. Design and testing of a unique active Compton-suppressed LaBr3(Ce) detector system for improved sensitivity assays of TRU in remote-handled TRU wastes

    Energy Technology Data Exchange (ETDEWEB)

    J. K. Hartwell; M. E. McIlwain; J. A. Kulisek

    2007-10-01

    The US Department of Energy’s transuranic (TRU) waste inventory includes about 4,500 m3 of remote-handled TRU (RH-TRU) wastes composed of a variety of containerized waste forms having a contact surface dose rate that exceeds 2 mSv/hr (200 mrem/hr) containing waste materials with a total TRU concentration greater than 3700 Bq/g (100 nCi/g). As part of a research project to investigate the use of active Compton-suppressed room-temperature gamma-ray detectors for direct non-destructive quantification of the TRU content of these RH-TRU wastes, we have designed and purchased a unique detector system using a LaBr3(Ce) primary detector and a NaI(Tl) suppression mantle. The LaBr3(Ce) primary detector is a cylindrical unit ~25 mm in diameter by 76 mm long viewed by a 38 mm diameter photomultiplier. The NaI(Tl) suppression mantle (secondary detector) is 175 mm by 175 mm with a center well that accommodates the primary detector. An important feature of this arrangement is the lack of any “can” between the primary and secondary detectors. These primary and secondary detectors are optically isolated by a thin layer (.003") of aluminized kapton, but the hermetic seal and thus the aluminum can surrounds the outer boundary of the detector system envelope. The hermetic seal at the primary detector PMT is at the PMT wall. This arrangement virtually eliminates the “dead” material between the primary and secondary detectors, a feature that preliminary modeling indicated would substantially improve the Compton suppression capability of this device. This paper presents both the expected performance of this unit determined from modeling with MCNPX, and the performance measured in our laboratory with radioactive sources.

  10. Theoretical evaluation of the Doppler broadening contribution to the angular resolution in CdZnTe Compton scattering detector

    International Nuclear Information System (INIS)

    Diaz Garcia, A.; Cabal Rodriguez, A.E.; Rubio Rodriguez, J. A.; Salicio Diez, J.; Perez Morales, J.M.; Vela Morales, O.; Willmott Zappacosta, C.; Van Espen, P.

    2011-01-01

    Electronically collimated Compton Cameras have been tested in Single Photon Emission Tomography (SPECT) systems instead of mechanically collimated gamma detectors in order to improve their limited sensitivity. One of the main factors that contribute to the worsening of the angular resolution and thus to the deterioration of the system spatial resolution is Doppler broadening. Double differential Klein-Nishina equation is used to consider the random movement of electron inside the crystal. It is important to perform this analysis for each particular material because is difficult to infer one simple Doppler broadening dependency of the atomic number Z. In high Z materials the internal electrons are strongly linked to the nucleus and therefore there can be found high momentums, but they represent just a small portion of the electrons that suffers Compton scattering. This work estimates the influence of the Doppler broadening in CdZnTe semiconductor for different incoming photon energies. For this means there are analyzed main Compton broadening processes in semiconductor Cd 0,8 Zn 0,2 Te with density ρ=5,85g/cm 3 . (Author)

  11. Compton scattering spectrum as a source of information of normal and neoplastic breast tissues' composition

    Energy Technology Data Exchange (ETDEWEB)

    Antoniassi, M.; Conceicao, A.L.C. [Departamento de Fisica-Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, 14040-901 Sao Paulo (Brazil); Poletti, M.E., E-mail: poletti@ffclrp.usp.br [Departamento de Fisica-Faculdade de Filosofia Ciencias e Letras de Ribeirao Preto, Universidade de Sao Paulo, Ribeirao Preto, 14040-901 Sao Paulo (Brazil)

    2012-07-15

    In this work we measured X-ray scatter spectra from normal and neoplastic breast tissues using photon energy of 17.44 keV and a scattering angle of 90 Degree-Sign , in order to study the shape (FWHM) of the Compton peaks. The obtained results for FWHM were discussed in terms of composition and histological characteristics of each tissue type. The statistical analysis shows that the distribution of FWHM of normal adipose breast tissue clearly differs from all other investigated tissues. Comparison between experimental values of FWHM and effective atomic number revealed a strong correlation between them, showing that the FWHM values can be used to provide information about elemental composition of the tissues. - Highlights: Black-Right-Pointing-Pointer X-ray scatter spectra from normal and neoplastic breast tissues were measured. Black-Right-Pointing-Pointer Shape (FWHM) of Compton peak was related with elemental composition and characteristics of each tissue type. Black-Right-Pointing-Pointer A statistical hypothesis test showed clear differences between normal and neoplastic breast tissues. Black-Right-Pointing-Pointer There is a strong correlation between experimental values of FWHM and effective atomic number. Black-Right-Pointing-Pointer Shape (FWHM) of Compton peak can be used to provide information about elemental composition of the tissues.

  12. Detection of detachments and inhomogeneities in frescos by Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Castellano, A. [Dipartimento di Scienza dei Materiali, Universita di Lecce, 73100 Lecce (Italy); INFN, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); Cesareo, R. [Istituto di Matematica e Fisica, Universita di Sassari, 07100 Sassari (Italy) and INFN, Sezione di Cagliari, Cittadella Universitaria di Monserrato, 09042 Cagliari (Italy)]. E-mail: cesareo@uniss.it; Buccolieri, G. [Dipartimento di Scienza dei Materiali, Universita di Lecce, 73100 Lecce (Italy); INFN, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); Donativi, M. [Dipartimento di Scienza dei Materiali, Universita di Lecce, 73100 Lecce (Italy); Palama, F. [Dipartimento di Scienza dei Materiali, Universita di Lecce, 73100 Lecce (Italy); INFN, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); Quarta, S. [Dipartimento di Scienza dei Materiali, Universita di Lecce, 73100 Lecce (Italy); INFN, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); De Nunzio, G. [Dipartimento di Scienza dei Materiali, Universita di Lecce, 73100 Lecce (Italy); INFN, Sezione di Lecce, via per Arnesano, 73100 Lecce (Italy); Brunetti, A. [Istituto di Matematica e Fisica, Universita di Sassari, 07100 Sassari (Italy); INFN, Sezione di Cagliari, Cittadella Universitaria di Monserrato, 09042 Cagliari (Italy); Marabelli, M. [Istituto Centrale del Restauro, P.zza S. Francesco di Paola, 00184 Rome (Italy); Santamaria, U. [Laboratori dei Musei Vaticani, Citta del Vaticano, Rome (Italy)

    2005-07-01

    A mobile instrument has been developed for the detection and mapping of detachments in frescos by using Compton back scattered photons. The instrument is mainly composed of a high energy X-ray tube, an X-ray detection system and a translation table. The instrument was first applied to samples simulating various detachment situations, and then transferred to the Vatican Museum to detect detachments and inhomogeneities in the stanza di Eliodoro, one of the 'Raphael's stanze'.

  13. A Compton-suppressed spectrometer for studies of chaos in nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Shriner, J.F. Jr. [Tennessee Technological Univ., Cookeville (United States); Bilpuch, E.G. [Duke University Press, Durham, NC (United States); Bybee, C.R. [Triangle Universities Nuclear Lab., Durham, NC (United States); Mitchell, G.E. [Triangle Universities Nuclear Lab., Durham, NC (United States); Moore, E.F. [Triangle Universities Nuclear Lab., Durham, NC (United States); Shriner, J.D. [Triangle Universities Nuclear Lab., Durham, NC (United States); Westerfeldt, C.R. [Duke University Press, Durham, NC (United States)

    1995-05-01

    One approach to studying chaos in quantum systems utilizes the statistical behavior of eigenvalues. Such analyses require data of very high quality, since both completeness and purity are essential. The design of a Compton-suppressed {gamma}-ray spectrometer for the purpose of establishing a nearly complete level scheme in {sup 30}P via the {sup 29}Si(p, {gamma}) reaction is described. Design criteria and implementation are discussed, and early results from the system are presented. (orig.).

  14. Deeply virtual compton scattering at 6 GeV

    International Nuclear Information System (INIS)

    Berthot, J.; Chen, J.P.; Chudakov, E.

    2000-01-01

    We propose a measurement of the Deep Virtual Compton Scattering process (DVCS) ep → epγ in Hall A at Jefferson Lab with a 6 GeV beam. We are able to explore the onset of Q 2 scaling, by measuring a beam helicity asymmetry for Q 2 ranging from 1.5 to 2.5 GeV 2 at x B ∼0.35. At this kinematics, the asymmetry is dominated by the DVCS - Bethe-Heitler (BH) interference, which is proportional to the imaginary part of the DVCS amplitude amplified by the full magnitude of the BH amplitude. The imaginary part of the DVCS amplitude is expected to scale early. Indeed, the imaginary part of the forward Compton amplitude measured in deep inelastic scattering (via the optical theorem) scales at Q 2 as low as 1 GeV 2 . If the scaling regime is reached, we will make an 8% measurement of the skewed parton distributions (SPD) contributing to the DVCS amplitude. Also, this experiment allows us to separately estimate the size of the higher-twist effects, since they are only suppressed by an additional factor 1/Q compared to the leading-twist term, and have a different angular dependence. We use a polarized electron beam and detect the scattered electron in the HRSe, the real photon in an electromagnetic calorimeter (under construction) and the recoil proton in a shielded scintillator array (to be constructed). This allows as to determine the difference in cross-sections for electrons of opposite helicities. This observable is directly linked to the SPD's. We estimate that 25 days of beam (600 hours) are needed to achieve this goal. (authors)

  15. Determination of oxide film thickness on aluminium using 14-MeV neutron activation and BET method

    International Nuclear Information System (INIS)

    Foerster, H.

    1983-01-01

    A new method is described for the determination of the mean film thickness of aluminium oxides by 14-MeV neutron activation analysis of the oxygen and by BET measurement of the surface area. The mean film thickness obtained is independent of the surface roughness. Stable oxide films consisting of only a few atomic layers of oxygen are detected on aluminium. (author)

  16. The X-ray to [Ne V]3426 flux ratio: discovering heavily obscured AGN in the distant Universe

    Science.gov (United States)

    Gilli, R.; Vignali, C.; Mignoli, M.; Iwasawa, K.; Comastri, A.; Zamorani, G.

    2010-09-01

    We investigate the possibility of using the ratio between the 2-10 keV flux and the [Ne V]3426 emission line flux (X/NeV) as a diagnostic diagram to discover heavily obscured, possibly Compton-thick active galactic nuclei (AGN) in the distant Universe. While it is on average about one order of magnitude fainter than the more commonly used [O III]5007 emission line, the [Ne V]3426 line can be observed with optical spectroscopy up to z~1.5, whereas the [O III]5007 line is redshifted out of the optical bands already at z~0.8. First, we calibrated a relation between X/NeV and the cold absorbing column density NH using a sample of 74 bright, nearby Seyferts with both X-ray and [Ne V] data available in the literature and for which the column density is determined unambiguously. Similar to what is found for the X-ray to [O III]5007 flux ratio (X/OIII), we found that the X/NeV ratio decreases towards high column densities, as expected if [Ne V]3426 emission is a good tracer of the AGN intrinsic power. Essentially all local Seyferts with X/NeV values below 15 are found to be Compton-thick objects. At X/NeV values below 100, the percentage of Compton-thick nuclei decreases to ~50%, but ~80% of the considered sample is still absorbed with NH > 1023 cm-2. Second, we applied this diagnostic diagram to different samples of distant obscured and unobscured QSOs in the Sloan Digital Sky Survey (SDSS). SDSS blue, unobscured, type-1 QSOs in the redshift range z = [0.1-1.5] indeed show X/NeV values typical of unobscured Seyfert 1s in the local Universe. Conversely, SDSS type-2 QSOs at z~0.5 classified either as Compton-thick or Compton-thin on the basis of their X/OIII ratio, would have mostly been classified in the same way based on the X/NeV ratio. We applied the X/NeV diagnostic diagram to 9 SDSS obscured QSOs in the redshift range z = [0.85-1.31], selected by means of their prominent [Ne V]3426 line (rest EW > 4 Å) and observed with Chandra ACIS-S for 10ks each (8 of them as part

  17. Monte Carlo simulation of muon-induced background of an anti-Compton gamma-ray spectrometer placed in a surface and underground laboratory

    CERN Document Server

    Vojtyla, P

    2005-01-01

    Simulations of cosmic ray muon induced background of an HPGe detector placed inside an anti-Compton shield on the surface and in shallow underground is described. Investigation of several model set-ups revealed some trends useful for design of low-level gamma-ray spectrometers. It has been found that background spectrum of an HPGe detector can be scaled down with the shielding depth. No important difference is observed when the same set-up of the anti-Compton spectrometer is positioned horizontally or vertically. A cosmic-muon rejection factor of at least 40 (at around 1 MeV) can be reached when the anti-Compton suppression is operational. The cosmicmuon background can be reduced to such a level that other background components prevail, like those from the residual contamination of the detector and shield materials and/or from radon, especially for the underground facilities.

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

    International Nuclear Information System (INIS)

    Quirk, Thomas J. IV

    2004-01-01

    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.

  19. Research of synchrotron radiation by virtual photon and compton scattering

    International Nuclear Information System (INIS)

    Meng Xianzhu

    2005-01-01

    This paper presents a new theory to explain the synchrotron radiation. When charged particle does circular motion in the accelerator, the magnetic field of the accelerator can be taken as periodic, and equivalent to virtual photon. By Compton scattering of virtual photon and charged particle, the virtual photon can be transformed into photon to radiate out. According to this theory, the formula of photon wavelength in synchrotron radiation is found out, and the calculation results of wavelength is consonant with experimental data. (author)

  20. Choroidal thickness and myopia in relation to physical activity - the CHAMPS Eye Study

    DEFF Research Database (Denmark)

    Lundberg, Kristian; Vestergaard, Anders Højslet; Jacobsen, Nina

    2018-01-01

    PURPOSE: To describe the relationship between choroidal thickness (CT) and myopia in relation to physical activity (PA) in a population-based child cohort. METHODS: In a prospective study of 307 children from the CHAMPS Study Denmark, we used objective data from GT3X accelerometer worn at four...

  1. Use of gamma spectroscopy in activation analysis; Utilisation de la spectrographie gamma dans l'analyse par activation

    Energy Technology Data Exchange (ETDEWEB)

    Leveque, [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

    1959-07-01

    Brief review of the principles of activation analysis: calculation of activities, decay curves, {beta} absorption curves, examples of application. - Principle and description of the {gamma} spectrograph. - Practical utilisation of the {gamma} spectrograph: analysis by activation, analysis by {beta} - x fluorescence. - Sensitivity limit of the method and precision of the measurements. - Possible improvements to the method: {gamma} spectroscopy with elimination of the Compton effect. (author) [French] Bref rappel des principes de l'analyse par activation: calcul des activites, courbes de decroissance, courbes d'absorption {beta}, exemples d'utilisation. - Principe et description du spectrographe {gamma}. - Utilisation pratique de la spectrographie {gamma}: analyse par activation, analyse par fluorescence {beta} - x. - Limite de sensibilite de la methode et precision des mesures. - Ameliorations possibles de la methode: spectrographe {gamma} avec elimination de l'effet Compton. (auteur)

  2. Use of a low-background and anti-Compton HpGe gamma-spectrometer in analyses of environmental samples

    Energy Technology Data Exchange (ETDEWEB)

    Qiong, Su; Yamin, Gao [Ministry of Public Health, Beijing, BJ (China). Lab. of Industrial Hygiene

    1989-12-01

    The results of application of a HpGe gamma-spectrometer in the analyses of enviromental samples are reported. The spectrometer has very low background and good property of Compton suppression. By comparison between the gamma-spectra with and without anti-coincidence shield for the same samples, the advantage in analysing environmental samples became apparent. In the analyses of carp samples, the ratio of specific activities of {sup 226}Ra in the flesh and bone of the carp was 1 to 35, which is basically in agreement with the ratio of the accumulation factors 1:37, as reported in the literature. Thus the spectrometer would play an important role in the research of the transfer of radionuclides of low activity in the environment. The method of gamma-ray data processing is also described.

  3. Use of a low-background and anti-Compton HpGe gamma-spectrometer in analyses of environmental samples

    International Nuclear Information System (INIS)

    Su Qiong; Gao Yamin

    1989-01-01

    The results of application of a HpGe gamma-spectrometer in the analyses of enviromental samples are reported. The spectrometer has very low background and good property of Compton suppression. By comparison between the gamma-spectra with and without anti-coincidence shield for the same samples, the advantage in analysing environmental samples became apparent. In the analyses of carp samples, the ratio of specific activities of 226 Ra in the flesh and bone of the carp was 1 to 35, which is basically in agreement with the ratio of the accumulation factors 1:37, as reported in the literature. Thus the spectrometer would play an important role in the research of the transfer of radionuclides of low activity in the environment. The method of gamma-ray data processing is also described

  4. A successful experimental observation of double-photon Compton scattering of γ rays using a single γ detector

    International Nuclear Information System (INIS)

    Saddi, M.B.; Sandhu, B.S.; Singh, B.

    2006-01-01

    The phenomenon of double-photon Compton scattering has been successfully observed using a single γ detector, a technique avoiding the use of the complicated slow-fast coincidence set-up used till now for observing this higher-order process. Here doubly differential collision cross-sections integrated over the directions of one of the two final photons, the direction of other one being kept fixed, are measured experimentally for 0.662 MeV incident γ photons. The energy spectra of the detected photons are observed as a long tail to the single-photon Compton line on the lower side of the full energy peak in the recorded scattered energy spectrum. The present results are in agreement with theory of this process

  5. Deeply virtual compton scattering at 6 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Berthot, J. [Universite Blaise Pascal, Clermont-Ferrand II, Lab. de Physique Corpusculaire (CNRS), 63 - Aubiere (France); Chen, J.P.; Chudakov, E. [National Accelerator Facility, Newport News, Virginia (United States)] [and others

    2000-07-01

    We propose a measurement of the Deep Virtual Compton Scattering process (DVCS) ep {yields} ep{gamma} in Hall A at Jefferson Lab with a 6 GeV beam. We are able to explore the onset of Q{sup 2} scaling, by measuring a beam helicity asymmetry for Q{sup 2} ranging from 1.5 to 2.5 GeV{sup 2} at x{sub B}{approx}0.35. At this kinematics, the asymmetry is dominated by the DVCS - Bethe-Heitler (BH) interference, which is proportional to the imaginary part of the DVCS amplitude amplified by the full magnitude of the BH amplitude. The imaginary part of the DVCS amplitude is expected to scale early. Indeed, the imaginary part of the forward Compton amplitude measured in deep inelastic scattering (via the optical theorem) scales at Q{sup 2} as low as 1 GeV{sup 2}. If the scaling regime is reached, we will make an 8% measurement of the skewed parton distributions (SPD) contributing to the DVCS amplitude. Also, this experiment allows us to separately estimate the size of the higher-twist effects, since they are only suppressed by an additional factor 1/Q compared to the leading-twist term, and have a different angular dependence. We use a polarized electron beam and detect the scattered electron in the HRSe, the real photon in an electromagnetic calorimeter (under construction) and the recoil proton in a shielded scintillator array (to be constructed). This allows as to determine the difference in cross-sections for electrons of opposite helicities. This observable is directly linked to the SPD's. We estimate that 25 days of beam (600 hours) are needed to achieve this goal. (authors)

  6. The simulation of an imaging gamma-ray Compton backscattering device using GEANT4

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  7. First measurement of $Z/\\gamma^{*}$ production in Compton scattering of quasi-real photons

    CERN Document Server

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

    1998-01-01

    We report the first observation of Z/gamma* production in Compton scattering of quasi-real photons. This is a subprocess of the reaction e+e- to e+e-Z/gamma*, where one of the final state electrons is undetected. Approximately 55 pb-1 of data collected in the year 1997 at an e+e- centre-of-mass energy of 183 GeV with the OPAL detector at LEP have been analysed. The Z/gamma* from Compton scattering has been detected in the hadronic decay channel. Within well defined kinematic bounds, we measure the product of cross-section and Z/gamma* branching ratio to hadrons to be (0.9+-0.3+-0.1) pb for events with a hadronic mass larger than 60 GeV, dominated by (e)eZ production. In the hadronic mass region between 5 GeV and 60 GeV, dominated by (e)egamma* production, this product is found to be (4.1+-1.6+-0.6) pb. Our results agree with the predictions of two Monte Carlo event generators, grc4f and PYTHIA.

  8. Haplotypes of the porcine peroxisome proliferator-activated receptor delta gene are associated with backfat thickness

    Directory of Open Access Journals (Sweden)

    Blöcker Helmut

    2009-11-01

    Full Text Available Abstract Background Peroxisome proliferator-activated receptor delta belongs to the nuclear receptor superfamily of ligand-inducible transcription factors. It is a key regulator of lipid metabolism. The peroxisome proliferator-activated receptor delta gene (PPARD has been assigned to a region on porcine chromosome 7, which harbours a quantitative trait locus for backfat. Thus, PPARD is considered a functional and positional candidate gene for backfat thickness. The purpose of this study was to test this candidate gene hypothesis in a cross of breeds that were highly divergent in lipid deposition characteristics. Results Screening for genetic variation in porcine PPARD revealed only silent mutations. Nevertheless, significant associations between PPARD haplotypes and backfat thickness were observed in the F2 generation of the Mangalitsa × Piétrain cross as well as a commercial German Landrace population. Haplotype 5 is associated with increased backfat in F2 Mangalitsa × Piétrain pigs, whereas haplotype 4 is associated with lower backfat thickness in the German Landrace population. Haplotype 4 and 5 carry the same alleles at all but one SNP. Interestingly, the opposite effects of PPARD haplotypes 4 and 5 on backfat thickness are reflected by opposite effects of these two haplotypes on PPAR-δ mRNA levels. Haplotype 4 significantly increases PPAR-δ mRNA levels, whereas haplotype 5 decreases mRNA levels of PPAR-δ. Conclusion This study provides evidence for an association between PPARD and backfat thickness. The association is substantiated by mRNA quantification. Further studies are required to clarify, whether the observed associations are caused by PPARD or are the result of linkage disequilibrium with a causal variant in a neighbouring gene.

  9. Nuclear photon science with inverse compton photon beam

    International Nuclear Information System (INIS)

    Fujiwara, Mamoru

    2007-01-01

    Recent developments of the synchrotron radiation facilities and intense lasers are now guiding us to a new research frontier with probes of a high energy GeV photon beam and an intense and short pulse MeV γ-ray beam. New directions of the science developments with photo-nuclear reactions are discussed. The inverse Compton γ-ray has two good advantages for searching for a microscopic quantum world; they are 1) good emittance and 2) high linear and circular polarizations. With these advantages, photon beams in the energy range from MeV to GeV are used for studying hadron structure, nuclear structure, astrophysics, materials science, as well as for applying medical science. (author)

  10. Deeply virtual Compton scattering from gauge/gravity duality

    Energy Technology Data Exchange (ETDEWEB)

    Costa, Miguel S.; Djuric, Marko [University of Porto (Portugal)

    2013-04-15

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

  11. Deeply virtual Compton scattering from gauge/gravity duality

    International Nuclear Information System (INIS)

    Costa, Miguel S.; Djurić, Marko

    2013-01-01

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

  12. High energy power-law tail in X-ray binaries and bulk Comptonization due to an outflow from a disk

    Science.gov (United States)

    Kumar, Nagendra

    2018-02-01

    We study the high energy power-law tail emission of X-ray binaries (XRBs) by a bulk Comptonization process which is usually observed in the very high soft (VHS) state of black hole (BH) XRBs and the high soft (HS) state of the neutron star (NS) and BH XRBs. Earlier, to generate the power-law tail in bulk Comptonization framework, a free-fall converging flow into BH or NS had been considered as a bulk region. In this work, for a bulk region we consider mainly an outflow geometry from the accretion disk which is bounded by a torus surrounding the compact object. We have two choices for an outflow geometry: (i) collimated flow and (ii) conical flow of opening angle θ _b and the axis is perpendicular to the disk. We also consider an azimuthal velocity of the torus fluids as a bulk motion where the fluids are rotating around the compact object (a torus flow). We find that the power-law tail can be generated in a torus flow having large optical depth and bulk speed (>0.75 c), and in conical flow with θ _b > ˜ 30° for a low value of Comptonizing medium temperature. Particularly, in conical flow the low opening angle is more favourable to generate the power-law tail in both the HS state and the VHS state. We notice that when the outflow is collimated, then the emergent spectrum does not have power-law component for a low Comptonizing medium temperature.

  13. Spatial representation of organic carbon and active-layer thickness of high latitude soils in CMIP5 earth system models

    Energy Technology Data Exchange (ETDEWEB)

    Mishra, Umakant; Drewniak, Beth; Jastrow, Julie D.; Matamala, Roser M.; Vitharana, U. W. A.

    2017-08-01

    Soil properties such as soil organic carbon (SOC) stocks and active-layer thickness are used in earth system models (F.SMs) to predict anthropogenic and climatic impacts on soil carbon dynamics, future changes in atmospheric greenhouse gas concentrations, and associated climate changes in the permafrost regions. Accurate representation of spatial and vertical distribution of these soil properties in ESMs is a prerequisite for redudng existing uncertainty in predicting carbon-climate feedbacks. We compared the spatial representation of SOC stocks and active-layer thicknesses predicted by the coupled Modellntercomparison Project Phase 5 { CMIP5) ESMs with those predicted from geospatial predictions, based on observation data for the state of Alaska, USA. For the geospatial modeling. we used soil profile observations {585 for SOC stocks and 153 for active-layer thickness) and environmental variables (climate, topography, land cover, and surficial geology types) and generated fine-resolution (50-m spatial resolution) predictions of SOC stocks (to 1-m depth) and active-layer thickness across Alaska. We found large inter-quartile range (2.5-5.5 m) in predicted active-layer thickness of CMIP5 modeled results and small inter-quartile range (11.5-22 kg m-2) in predicted SOC stocks. The spatial coefficient of variability of active-layer thickness and SOC stocks were lower in CMIP5 predictions compared to our geospatial estimates when gridded at similar spatial resolutions (24.7 compared to 30% and 29 compared to 38%, respectively). However, prediction errors. when calculated for independent validation sites, were several times larger in ESM predictions compared to geospatial predictions. Primaly factors leading to observed differences were ( 1) lack of spatial heterogeneity in ESM predictions, (2) differences in assumptions concerning environmental controls, and (3) the absence of pedogenic processes in ESM model structures. Our results suggest that efforts to incorporate

  14. Sensitivity of Shallow Land Burial to neutron environment and activation cross sections in IFE thick-liquid concepts

    Energy Technology Data Exchange (ETDEWEB)

    Cabellos, O.; Sanz, J. [Institute of Nuclear Fusion, UPM (Spain); Cabellos, O.; Garcia-Herranz, N. [Dept. of Nuclear Engineering, UPM (Spain); Sanz, J. [Dept. of Power Engineering, UNED (Spain); Reyes, S.; Latkowski, J. [Livermore National Lab., LLNL (United States)

    2006-06-15

    A comprehensive assessment on the eligibility of reduced activation (RA) steels as structural chamber material in Inertial Fusion Energy thick-liquid concepts is performed. As far as alloying elements, it is shown that the activation of tungsten is a question to discuss. Regarding impurity elements, it is analyzed if they could question the possibility of obtaining real RA steels for shallow land burial (SLB). The effect of the thickness of the liquid wall on the SLB response of alloying and impurity elements is computed. It seems that a reasonable liquid thickness of about 80 cm is allowable to obtain SLB acceptability of real RA steels. And above all, we have estimated the impact of cross section uncertainties when addressing the former questions, and we identify those to be improved. The necessary improvement of some tungsten and niobium cross sections is justified. (authors)

  15. Does an atom interferometer test the gravitational redshift at the Compton frequency?

    International Nuclear Information System (INIS)

    Wolf, Peter; Borde, Christian J; Blanchet, Luc; Reynaud, Serge; Salomon, Christophe; Cohen-Tannoudji, Claude

    2011-01-01

    Atom interferometers allow the measurement of the acceleration of freely falling atoms with respect to an experimental platform at rest on Earth's surface. Such experiments have been used to test the universality of free fall by comparing the acceleration of the atoms to that of a classical freely falling object. In a recent paper, Mueller et al (2010 Nature 463 926-9) argued that atom interferometers also provide a very accurate test of the gravitational redshift (or universality of clock rates). Considering the atom as a clock operating at the Compton frequency associated with the rest mass, they claimed that the interferometer measures the gravitational redshift between the atom-clocks in the two paths of the interferometer at different values of gravitational potentials. In this paper, we analyze this claim in the frame of general relativity and of different alternative theories. We show that the difference of 'Compton phases' between the two paths of the interferometer is actually zero in a large class of theories, including general relativity, all metric theories of gravity, most non-metric theories and most theoretical frameworks used to interpret the violations of the equivalence principle. Therefore, in most plausible theoretical frameworks, there is no redshift effect and atom interferometers only test the universality of free fall. We also show that frameworks in which atom interferometers would test the redshift pose serious problems, such as (i) violation of the Schiff conjecture, (ii) violation of the Feynman path integral formulation of quantum mechanics and of the principle of least action for matter waves, (iii) violation of energy conservation, and more generally (iv) violation of the particle-wave duality in quantum mechanics. Standard quantum mechanics is no longer valid in such frameworks, so that a consistent interpretation of the experiment would require an alternative formulation of quantum mechanics. As such an alternative has not been

  16. Concept and realization of the A4 Compton backscattering polarimeter at MAMI

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Han

    2008-12-15

    The main concern of the A4 parity violation experiment at the Mainzer Microtron accelerator facility is to study the electric and magnetic contributions of strange quarks to the charge and magnetism of the nucleons at the low momentum transfer region. More precisely, the A4 collaboration investigates the strange quarks' contribution to the electric and magnetic vector form factors of the nucleons. Thus, it is important that the A4 experiment uses an adequate and precise non-destructive online monitoring tool for the electron beam polarization when measuring single spin asymmetries in elastic scattering of polarized electrons from unpolarized nucleons. As a consequence, the A4 Compton backscattering polarimeter was designed and installed such that we can take the absolute measurement of the electron beam polarization without interruption to the parity violation experiment. The present study shows the development of an electron beam line that is called the chicane for the A4 Compton backscattering polarimeter. The chicane is an electron beam transport line and provides an interaction region where the electron beam and the laser beam overlap. After studying the properties of beam line components carefully, we developed an electron beam control system that makes a beam overlap between the electron beam and the laser beam. Using the system, we can easily achieve the beam overlap in a short time. The electron control system, of which the performance is outstanding, is being used in production beam times. And the study presents the development of a scintillating fiber electron detector that reduces the statistical error in the electron polarization measurement. We totally redesigned the scintillating fiber detector. The data that were taken during a 2008 beam time shows a huge background suppression, approximately 80 percent, while leaving the Compton spectra almost unchanged when a coincidence between the fiber detector and the photon detector is used. Thus, the

  17. Exclusive compton scattering on the proton

    International Nuclear Information System (INIS)

    Chen, J.P.; Chudakov, E.; DeJager, C.; Degtyarenko, P.; Ent, R.; Gomez, J.; Hansen, O.; Keppel, C.; Klein, F.; Kuss, M.

    1999-01-01

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

  18. Exclusive compton scattering on the proton

    Energy Technology Data Exchange (ETDEWEB)

    Chen, J.P.; Chudakov, E.; DeJager, C.; Degtyarenko, P.; Ent, R.; Gomez, J.; Hansen, O.; Keppel, C.; Klein, F.; Kuss, M. [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)] [and others

    1999-07-01

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

  19. Exclusive Compton Scattering on the Proton

    International Nuclear Information System (INIS)

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

    1999-01-01

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

  20. Experimental test of Bell`s inequalities using angular correlation of compton-scattered annihilation photons

    Energy Technology Data Exchange (ETDEWEB)

    Osuch, S.; Popkiewicz, M.; Szeflinski, Z.; Wilhelmi, Z. [Warsaw Univ., Inst. of Experimental Physics, Warsaw (Poland)

    1995-12-31

    The Bell`s inequality has been experimentally tested using angular correlation of Compton-scattered photons from annihilation of positrons emitted from {sup 22}Na source. The result shows a better agreement with the quantum mechanics predictions rather than with the Bell`s inequality. 7 refs, 5 figs, 1 tab.

  1. Gamma ray burst source locations with the Ulysses/Compton/PVO Network

    International Nuclear Information System (INIS)

    Cline, T.L.; Hurley, K.C.; Boer, M.; Sommer, M.; Niel, M.; Fishman, G.J.; Kouveliotou, C.; Meegan, C.A.; Paciesas, W.S.; Wilson, R.B.; Laros, J.G.; Klebesadel, R.W.

    1991-01-01

    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

  2. Plume Activity and Tidal Deformation on Enceladus Influenced by Faults and Variable Ice Shell Thickness.

    Science.gov (United States)

    Běhounková, Marie; Souček, Ondřej; Hron, Jaroslav; Čadek, Ondřej

    2017-09-01

    We investigated the effect of variations in ice shell thickness and of the tiger stripe fractures crossing Enceladus' south polar terrain on the moon's tidal deformation by performing finite element calculations in three-dimensional geometry. The combination of thinning in the polar region and the presence of faults has a synergistic effect that leads to an increase of both the displacement and stress in the south polar terrain by an order of magnitude compared to that of the traditional model with a uniform shell thickness and without faults. Assuming a simplified conductive heat transfer and neglecting the heat sources below the ice shell, we computed the global heat budget of the ice shell. For the inelastic properties of the shell described by a Maxwell viscoelastic model, we show that unrealistically low average viscosity of the order of 10 13 Pa s is necessary for preserving the volume of the ocean, suggesting the important role of the heat sources in the deep interior. Similarly, low viscosity is required to predict the observed delay of the plume activity, which hints at other delaying mechanisms than just the viscoelasticity of the ice shell. The presence of faults results in large spatial and temporal heterogeneity of geysering activity compared to the traditional models without faults. Our model contributes to understanding the physical mechanisms that control the fault activity, and it provides potentially useful information for future missions that will sample the plume for evidence of life. Key Words: Enceladus-Tidal deformation-Faults-Variable ice shell thickness-Tidal heating-Plume activity and timing. Astrobiology 17, 941-954.

  3. Determination of elemental concentrations in airborne particulate matter in the City of Santiago de Chile, through neutron activation analysis using epithermal neutrons and Compton suppression system

    International Nuclear Information System (INIS)

    Rojas S, Ximena

    1995-01-01

    In order to optimize the Neutron-Activation Analysis (NAA) technique currently carried out in our country, the present work was carried out in the United States where irradiations with epithermal neutrons and a Compton suppression system were used, which allowed the characterization of aerosols of the city of Santiago de Chile. With this purpose, 54 filters of polycarbonate membranes were analysed with aerosols collected in an area of the capital during Spring 1993 and Winter of 1994. As a result, an improvement in the detection limits was observed, specially in elements such as Ni and Zn, which are not easily detectable through NAA. The application of both systems also permits the usage of this technique in geological and biological samples, where the presence of Na, Al and Cl obstruct the determination of some elements. The determined elements in both fractions were Mn, V, Cu, As, Sb, Co, Br, Cl, Ni, Zn, Ca, Al, Na and Fe. (author). 8 refs., 7 figs., 9 tabs

  4. Landmine Detection: on the Role of Soil Composition in the Imaging Capabilities of Gamma-ray Compton Backscattering

    International Nuclear Information System (INIS)

    Cortes, M.L.; Merchan, E.; Blanco, W.J.; Cristancho, F.; Gerl, J.; Ameil, F.

    2010-01-01

    Two issues related with the use of γ-ray Compton backscattering as an imaging technique are addressed: γ-soil interaction, and image processing. Promising methodologies are described in both topics. (author)

  5. Heavily Obscured AGN with SIMBOL-X

    International Nuclear Information System (INIS)

    Ceca, R. Della; Caccianiga, A.; Severgnini, P.

    2009-01-01

    By comparing an optically selected sample of narrow lines AGN with an X-ray selected sample of AGN we have recently derived an estimate of the intrinsic (i.e. before absorption) 2-10 keV luminosity function (XLF) of Compton Thick AGNs. We will use this XLF to derive the number of Compton Thick AGN that will be found in the SIMBOL-X survey(s).

  6. Heavily Obscured AGN with SIMBOL-X

    Science.gov (United States)

    Della Ceca, R.; Caccianiga, A.; Severgnini, P.

    2009-05-01

    By comparing an optically selected sample of narrow lines AGN with an X-ray selected sample of AGN we have recently derived an estimate of the intrinsic (i.e. before absorption) 2-10 keV luminosity function (XLF) of Compton Thick AGNs. We will use this XLF to derive the number of Compton Thick AGN that will be found in the SIMBOL-X survey(s).

  7. Light Higgs production at the Compton Collider

    International Nuclear Information System (INIS)

    Jikia, G.; Soeldner-Rembold, S.

    2000-01-01

    We have studied the production of a light Higgs boson with a mass of 120 GeV in photon-photon collisions at a Compton collider. The event generator for the backgrounds to a Higgs signal due to b-barb and c-barc heavy quark pair production in polarized γγ collisions is based on a complete next-to-leading order (NLO) perturbative QCD calculation. For J z = 0 the large double-logarithmic corrections up to four loops are also included. It is shown that the two-photon width of the Higgs boson can be measured with high statistical accuracy of about 2% for integrated γγ luminosity in the hard part of the spectrum of 40 fb -1 . As a result the total Higgs boson width can be calculated in a model independent way to an accuracy of about 14%

  8. Experimental determination of absolute-scale compton cross sections using the K X-ray escape and a comparison with three versions of the impulse approximation

    International Nuclear Information System (INIS)

    Pasic, S.; Uroic, M.; Tocilj, Z.; Majer, M.; Gamulin, O.; Bokulic, T.; Ilakovac, K.

    2005-01-01

    Double-differential Compton cross sections at two incident photon energies of 68.9 and 70.8 keV (mercury Kα X-rays) at the scattering angle of about 172 deg were measured in germanium using the coincidence technique with a detector as the scatterer. The cross sections were determined by normalization of the Compton spectra to the peaks due to the escape of characteristic Kα and Kβ X-rays from the target detector. This new approach of determination of absolute-scale Compton cross sections can also be applied in widely used single-mode measurements (source-scatterer-detector assembly). Our analysis shows that the new method is especially convenient and accurate at lower incident photon energies above the K-edge in the target atoms. The experimental results are compared with the non-relativistic impulse approximation, the frequently used simplified version of the relativistic impulse approximation and the non-relativistic impulse approximation used with the relativistic expression for the atomic electron momentum in the direction of the photon momentum transfer. Contrary to our expectation, the non-relativistic impulse approximation clearly gives the best agreement with the experimental data in the region of the Compton peak

  9. Compton scatter and X-ray crosstalk and the use of very thin intercrystal septa in high-resolution PET detectors

    International Nuclear Information System (INIS)

    Levin, C.S.; Tornai, M.P.; Cherry, S.R.; MacDonald, L.R.; Hoffman, E.J.

    1997-01-01

    To improve spatial resolution, positron emission tomography (PET) systems are being developed with finer detector elements. Unfortunately, using a smaller crystal size increases intercrystal Compton scatter and X-ray escape crosstalk, causing positioning errors that can lead to degradation of image contrast. The authors investigated the use of extremely thin lead strips for passive shielding of this intercrystal crosstalk. Using annihilation gamma rays and small Bismuth Germanate (BGO) crystal detectors in coincidence, crosstalk studies were performed with either two small adjacent crystals [(one-dimensional) (1-D)] or one crystal inside a volume of BGO [(two-dimensional) (2-D)]. The fraction of Compton scattered events from one crystal into an adjacent one was reduced, on average, by a factor of 3.2 (2.2) in the 1-D experiment and by a factor of 3.0 (2.1) in 2-D one, with a 300 (150)-microm-thick lead strip in between the crystals and a 300--700-keV energy window in both crystals. The authors could not measure a reduction in bismuth X-ray crosstalk with the sue of lead septa due to the production of lead X-rays of similar energy. The full-width at half-maximum (FWHM) of the coincident point-spread function (CPSF) was not significantly different for the 1- and 2-D studies, with or without the different septa in place. However, the FWTM was roughly 20% smaller with the 300-microm lead shielding in place. These results indicate that intercrystal crosstalk does not affect the positioning resolution at FWHM, but does affect the tails of the CPSF. Thus, without introducing any additional dead area, an insertion of very thin lead strips can reduce the extent of positioning errors. Reducing the intercrystal crosstalk in a high-resolution PET detector array could potentially improve tomographic image contrast in situations where intercrystal crosstalk plays a significant role in event mispositioning

  10. TU-CD-304-10: Development and Optimization of “Compton Lens” Collimator Design for Increased Dose Rate in SRS

    Energy Technology Data Exchange (ETDEWEB)

    Shepard, A; Bender, E [The University of Wisconsin-Madison, Madison, WI (United States)

    2015-06-15

    Purpose: To provide a proof of concept for a new collimator design to increase the dose rate at isocenter for stereotactic radiosurgery (SRS) treatments by taking advantage of off axis Compton scattered photons which are attenuated in current collimators. Methods: A fundamentally new collimator design was developed and optimized by introducing a series of slits to a standard block collimator. The introduction of slits allowed for initially off axis radiation that was scattered in the direction of the target to contribute to the target dose. For optimization, the design was broken into two parts: an upper interaction plate where primary scattering occurs, and a lower “Compton slit” region which allows for scattered photons traveling toward the target to reach isocenter. To optimize the design, a series of simulations were performed using MCNP6 in which several key parameters were adjusted and the output was compared to a standard collimator. Key parameters modified included the collimator material, cone size, and interaction plate thickness. The effects of using energies different than the traditional 6 MV beam were also explored. Results: An optimized collimator design utilizing a solid interaction plate with a Cesium-137 beam and a 4 mm cone size resulted in a dose rate increase on the order of 5% relative to standard collimators in use. Currently, designs incorporating a Cesium-137 source are the most feasible due to necessary size and weight concerns for 6 MV beams. Conclusion: Preliminary designs provide a proof of concept and indicate a potential to improve upon the dose rate of current collimators while not largely compromising the sharp dose falloff inherent to SRS. Further optimization into the geometry and positioning of the interaction plate, as well as slit optimization, will likely lead to further dose rate increases than were observed in this study. Funding for this work was provided by the Wisconsin Alumni Research Foundation (WARF). Authors have

  11. Meson-induced correlations of nucleons in nuclear Compton scattering

    International Nuclear Information System (INIS)

    Huett, M.; Milstein, A.I.

    1998-01-01

    The nonresonant (seagull) contribution to the nuclear Compton amplitude at low energies is strongly influenced by nucleon correlations arising from meson exchange. We study this problem in a modified Fermi gas model, where nuclear correlation functions are obtained with the help of perturbation theory. The dependence of the mesonic seagull amplitude on the nuclear radius is investigated and the influence of a realistic nuclear density on this amplitude is discussed. We found that different form factors appear for the static part (proportional to the enhancement constant κ) of the mesonic seagull amplitude and for the parts, which contain the contribution from electromagnetic polarizabilities. copyright 1998 The American Physical Society

  12. Generation of laser Compton gamma-rays using Compact ERL

    International Nuclear Information System (INIS)

    Shizuma, Toshiyuki; Hajima, Ryoichi; Nagai, Ryoji; Hayakawa, Takehito; Mori, Michiaki; Seya, Michio

    2015-01-01

    Nondestructive isotope-specific assay system using nuclear resonance fluorescence has been developed at JAEA. In this system, intense, mono-energetic laser Compton scattering (LCS) gamma-rays are generated by combining an energy recovery linac (ERL) and laser enhancement cavity. As technical development for such an intense gamma-ray source, we demonstrated generation of LCS gamma-rays using Compact ERL (supported by the Ministry of Education, Culture, Sports, Science and Technology) developed in collaboration with KEK. We also measured X-ray fluorescence for elements near iron region by using mono-energetic LCS gamma-rays. In this presentation, we will show results of the experiment and future plan. (author)

  13. Sources of the X-rays Based on Compton Scattering

    International Nuclear Information System (INIS)

    Androsov, V.; Bulyak, E.; Gladkikh, P.; Karnaukhov, I.; Mytsykov, A.; Telegin, Yu.; Shcherbakov, A.; Zelinsky, A.

    2007-01-01

    The principles of the intense X-rays generation by laser beam scattering on a relativistic electron beam are described and description of facilities assigned to produce the X-rays based on Compton scattering is presented. The possibilities of various types of such facilities are estimated and discussed. The source of the X-rays based on a storage ring with low beam energy is described in details and advantages of the sources of such type are discussed.The results of calculation and numerical simulation carried out for laser electron storage ring NESTOR that is under development in NSC KIPT show wide prospects of the accelerator facility of such type

  14. Colloidal titania-silica-iron oxide nanocomposites and the effect from silica thickness on the photocatalytic and bactericidal activities

    Energy Technology Data Exchange (ETDEWEB)

    Chanhom, Padtaraporn [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Charoenlap, Nisanart [Laboratory of Biotechnology, Chulabhorn Research Institute, Bangkok 10210 (Thailand); Tomapatanaget, Boosayarat [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand); Insin, Numpon, E-mail: Numpon.I@chula.ac.th [Department of Chemistry, Faculty of Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2017-04-01

    New types of colloidal multifunctional nanocomposites that combine superparamagnetic character and high photocatalytic activity were synthesized and investigated. The superparamagnetic nanocomposites composed of anatase titania, silica, and iron oxide nanoparticles (TSI) were synthesized using thermal decomposition method followed by microemulsion method, without calcination at high temperature. Different techniques including X-ray diffraction (XRD) and transmission electron microscope (TEM) were used to characterize and confirm the structure of the nanocomposites. These nanocomposites showed high photocatalytic activity when used in the photodegradation of methylene blue under irradiation with a black light lamp. Moreover, the nanocomposites exhibited high antibacterial properties. From our study, the nanocomposites can be useful in various applications such as removal of pollutants with readily separation from the environment using an external magnetic field. These composites could effectively photo-degrade the dye at least three cycles without regeneration. The effects of silica shell thickness on the photocatalytic activity was investigated, and the thickness of 6 nm of the silica interlayer is enough for the inhibition of electron translocation between titania and iron oxide nanoparticles and maintaining the efficiency of photocatalytic activity of titania nanoparticles. - Highlights: • New colloidal nanocomposites of iron oxide-silica-titania were prepared. • The nanocomposites exhibited high photocatalytic activity with magnetic response. • The effects of silica thickness on photocatalytic activity were investigated. • Bactericidal activity of the nanocomposites was demonstrated.

  15. Effects of hippotherapy on the thickness of deep abdominal muscles and activity of daily living in children with intellectual disabilities.

    Science.gov (United States)

    Lee, JiHyun; Yun, Chang-Kyo

    2017-04-01

    [Purpose] The purpose of this study is to investigate the effect of hippotherapy exercise on the thickness of deep abdominal muscles and daily activities of children with intellectual disabilities. [Subjects and Methods] Seven children with intellectual disabilities were treated with hippotherapy for 30 minutes twice a week for 6 weeks. The thickness of deep abdominal muscles and Functional Independence Measure (FIM) of the subjects were measured by ultrasonography before and after the experiment. [Results] There was no significant change in the thickness of the External Oblique and Internal Oblique muscles, but there was a statistically significant change in Transverse Adbominis thickness and FIM score after treatment compared to before treatment. [Conclusion] Hippotherapy exercise has a positive effect on the improvement of Transverse Abdominis (TrA) and activity of daily livings of children with intellectual disabilities.

  16. Measurement of Deeply Virtual Compton Scattering at HERA

    CERN Document Server

    Aktas, A.; Anthonis, T.; Aplin, S.; Asmone, A.; Astvatsatourov, A.; Babaev, A.; Backovic, S.; Bahr, J.; Baghdasaryan, A.; Baranov, P.; Barrelet, E.; Bartel, W.; Baudrand, S.; Baumgartner, S.; Becker, J.; Beckingham, M.; Behnke, O.; Behrendt, O.; Belousov, A.; Berger, Ch.; Berger, N.; Bizot, J.C.; Boenig, M.-O.; Boudry, V.; Bracinik, J.; Brandt, G.; Brisson, V.; Brown, D.P.; Bruncko, D.; Busser, F.W.; Bunyatyan, A.; Buschhorn, G.; Bystritskaya, L.; Campbell, A.J.; Caron, S.; Cassol-Brunner, F.; Cerny, K.; Cerny, V.; Chekelian, V.; Contreras, J.G.; Coughlan, J.A.; Cox, B.E.; Cozzika, G.; Cvach, J.; Dainton, J.B.; Dau, W.D.; Daum, K.; de Boer, Y.; Delcourt, B.; Demirchyan, R.; De Roeck, A.; Desch, K.; De Wolf, E.A.; Diaconu, C.; Dodonov, V.; Dubak, A.; Eckerlin, Guenter; Efremenko, V.; Egli, S.; Eichler, R.; Eisele, F.; Ellerbrock, M.; Elsen, E.; Erdmann, W.; Essenov, S.; Falkewicz, A.; Faulkner, P.J.W.; Favart, L.; Fedotov, A.; Felst, R.; Ferencei, J.; Finke, L.; Fleischer, M.; Fleischmann, P.; Fleming, Y.H.; Flucke, G.; Fomenko, A.; Foresti, I.; Franke, G.; Frisson, T.; Gabathuler, E.; Garutti, E.; Gayler, J.; Gerlich, C.; Ghazaryan, Samvel; Ginzburgskaya, S.; Glazov, A.; Glushkov, I.; Goerlich, L.; Goettlich, M.; Gogitidze, N.; Gorbounov, S.; Goyon, C.; Grab, C.; Greenshaw, T.; Gregori, M.; Grell, B.R.; Grindhammer, Guenter; Gwilliam, C.; Haidt, D.; Hajduk, L.; Haller, J.; Hansson, M.; Heinzelmann, G.; Henderson, R.C.W.; Henschel, H.; Henshaw, O.; Herrera, G.; Hildebrandt, M.; Hiller, K.H.; Hoffmann, D.; Horisberger, R.; Hovhannisyan, A.; Ibbotson, M.; Ismail, M.; Jacquet, M.; Janauschek, L.; Janssen, X.; Jemanov, V.; Jonsson, L.; Johnson, D.P.; Jung, H.; Kapichine, M.; Katzy, J.; Keller, N.; Kenyon, I.R.; Kiesling, Christian M.; Klein, M.; Kleinwort, C.; Klimkovich, T.; Kluge, T.; Knies, G.; Knutsson, A.; Korbel, V.; Kostka, P.; Koutouev, R.; Krastev, K.; Kretzschmar, J.; Kropivnitskaya, A.; Kruger, K.; Kuckens, J.; Landon, M.P.J.; Lange, W.; Lastovicka, T.; Lastovicka-Medin, G.; Laycock, P.; Lebedev, A.; Leiner, B.; Lendermann, V.; Levonian, S.; Lindfeld, L.; Lipka, K.; List, B.; Lobodzinska, E.; Loktionova, N.; Lopez-Fernandez, R.; Lubimov, V.; Lucaci-Timoce, A.-I.; Lueders, H.; Luke, D.; Lux, T.; Lytkin, L.; Makankine, A.; Malden, N.; Malinovski, E.; Mangano, S.; Marage, P.; Marshall, R.; Martisikova, M.; Martyn, H.-U.; Maxeld, S.J.; Meer, D.; Mehta, A.; Meier, K.; Meyer, A.B.; Meyer, H.; Meyer, J.; Mikocki, S.; Milcewicz-Mika, I.; Milstead, D.; Mladenov, D.; Mohamed, A.; Moreau, F.; Morozov, A.; Morris, J.V.; Mozer, Matthias Ulrich; Muller, K.; Murin, P.; Nankov, K.; Naroska, B.; Naumann, Th.; Newman, Paul R.; Niebuhr, C.; Nikiforov, A.; Nikitin, D.; Nowak, G.; Nozicka, M.; Oganezov, R.; Olivier, B.; Olsson, J.E.; Osman, S.; Ozerov, D.; Palichik, V.; Panagoulias, I.; Papadopoulou, T.; Pascaud, C.; Patel, G.D.; Peez, M.; Perez, E.; Perez-Astudillo, D.; Perieanu, A.; Petrukhin, A.; Pitzl, D.; Placakyte, R.; Portheault, B.; Povh, B.; Prideaux, P.; Raicevic, N.; Reimer, P.; Rimmer, A.; Risler, C.; Rizvi, E.; Robmann, P.; Roland, B.; Roosen, R.; Rostovtsev, A.; Rurikova, Z.; Rusakov, S.; Salvaire, F.; Sankey, D.P.C.; Sauvan, E.; Schatzel, S.; Schilling, F.-P.; Schmidt, S.; Schmitt, S.; Schmitz, C.; Schoeffel, L.; Schoning, A.; Schroder, V.; Schultz-Coulon, H.-C.; Sedlak, K.; Sefkow, F.; Sheviakov, I.; Shtarkov, L.N.; Sirois, Y.; Sloan, T.; Smirnov, P.; Soloviev, Y.; South, D.; Spaskov, V.; Specka, Arnd E.; Stella, B.; Stiewe, J.; Strauch, I.; Straumann, U.; Tchoulakov, V.; Thompson, Graham; Thompson, P.D.; Tomasz, F.; Traynor, D.; Truoel, Peter; Tsakov, I.; Tsipolitis, G.; Tsurin, I.; Turnau, J.; Tzamariudaki, E.; Urban, Marcel; Usik, A.; Utkin, D.; Valkar, S.; Valkarova, A.; Vallee, C.; Van Mechelen, P.; Van Remortel, N.; Vargas Trevino, A.; Vazdik, Y.; Veelken, C.; Vest, A.; Vinokurova, S.; Volchinski, V.; Vujicic, B.; Wacker, K.; Wagner, J.; Weber, G.; Weber, R.; Wegener, D.; Werner, C.; Werner, N.; Wessels, M.; Wessling, B.; Wigmore, C.; Wissing, Ch.; Wolf, R.; Wunsch, E.; Xella, S.; Yan, W.; Yeganov, V.; Zacek, J.; Zalesak, J.; Zhang, Z.; Zhelezov, A.; Zhokin, A.; Zimmermann, J.; Zimmermann, T.; Zohrabyan, H.; Zomer, F.

    2005-01-01

    A measurement is presented of elastic deeply virtual Compton scattering \\gamma* p \\to \\gamma p made using e^+ p collision data corresponding to a luminosity of 46.5 pb^{-1}, taken with the H1 detector at HERA. The cross section is measured as a function of the photon virtuality, Q^2, the invariant mass of the \\gamma* p system, W, and for the first time, differentially in the squared momentum transfer at the proton vertex, t, in the kinematic range 2 < Q^2 < 80 GeV^2, 30 < W < 140 GeV and |t| < 1 GeV^2. QCD based calculations at next-to-leading order using generalized parton distributions can describe the data, as can colour dipole model predictions.

  17. Compton scattering and electron-atom scattering in an elliptically polarized laser field of relativistic radiation power

    International Nuclear Information System (INIS)

    Panek, P.; Kaminski, J.Z.; Ehlotzky, F.

    2003-01-01

    Presently available laser sources can yield powers for which the ponderomotive energy of an electron U p can be equal to or even larger than the rest energy mc 2 of an electron. Therefore it has become of interest to consider fundamental radiation-induced or assisted processes in such powerful laser fields. In the present work we consider laser-induced Compton scattering and laser-assisted electron atom scattering in such fields, assuming that the laser beam has arbitrary elliptic polarization. We investigate in detail the angular and polarisation dependence of the differential cross-sections of the two laser-induced or laser-assisted nonlinear processes as a function of the order N of absorbed or emitted laser photons ω. The present work is a generalization of our previous analysis of Compton scattering and electron-atom scattering in a linearly polarized laser field. (authors)

  18. Leveraging Subsidence in Permafrost with Remotely Sensed Active Layer Thickness (ReSALT) Products

    Science.gov (United States)

    Schaefer, K. M.; Chen, A.; Chen, J.; Chen, R. H.; Liu, L.; Michaelides, R. J.; Moghaddam, M.; Parsekian, A.; Tabatabaeenejad, A.; Thompson, J. A.; Zebker, H. A.; Meyer, F. J.

    2017-12-01

    The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence in permafrost regions. Seasonal subsidence results from the expansion of soil water into ice as the surface soil or active layer freezes and thaws each year. Subsidence trends result from large-scale thaw of permafrost and from the melting and subsequent drainage of excess ground ice in permafrost-affected soils. The attached figure shows the 2006-2010 average seasonal subsidence from ReSALT around Barrow, Alaska. The average active layer thickness (the maximum surface thaw depth during summer) is 30-40 cm, resulting in an average seasonal subsidence of 1-3 cm. Analysis of the seasonal subsidence and subsidence trends provides valuable insights into important permafrost processes, such as the freeze/thaw of the active layer, large-scale thawing due to climate change, the impact of fire, and infrastructure vulnerability. ReSALT supports the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential NASA-ISRO Synthetic Aperture Radar (NISAR) product. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. Here we present examples of ReSALT products in Alaska to highlight the untapped potential of the InSAR technique to understand permafrost dynamics, with a strong emphasis on the underlying processes that drive the subsidence.

  19. K-factors in the deep inelastic Compton and Drell-Yan processes

    International Nuclear Information System (INIS)

    Czechowski, A.; Krawczyk, M.

    1983-01-01

    The associated production of hadrons is used to answer the question about the nature of large QCD corrections for hard processes. The results of the order α s calculation of K-factors for the deep inelastic Compton process and some predictions for the large p perpendicular to Drell-Yan pair production in hadron-hadron collision are presented. In the soft gluon approximation a significant difference between K-factors corresponding to different inclusive distributions in each of these processes is found. (author)

  20. Bulk Comptonization: new hints from the luminous blazar 4C+25.05

    Science.gov (United States)

    Kammoun, E. S.; Nardini, E.; Risaliti, G.; Ghisellini, G.; Behar, E.; Celotti, A.

    2018-01-01

    Blazars are often characterized by a spectral break at soft X-rays, whose origin is still debated. While most sources show a flattening, some exhibit a blackbody-like soft excess with temperatures of the order of ∼0.1 keV, similar to low-luminosity, non-jetted Seyferts. Here, we present the analysis of the simultaneous XMM-Newton and NuSTAR observations of the luminous flat-spectrum radio quasar 4C+25.05 (z = 2.368). The observed 0.3-30 keV spectrum is best described by the sum of a hard X-ray power law (Γ = 1.38_{-0.03}^{+0.05}) and a soft component, approximated by a blackbody with kT_BB = 0.66_{-0.04}^{+0.05} keV (rest frame). If the spectrum of 4C+25.05 is interpreted in the context of bulk Comptonization by cold electrons of broad-line region photons emitted in the direction of the jet, such an unusual temperature implies a bulk Lorentz factor of the jet of Γbulk ∼ 11.7. Bulk Comptonization is expected to be ubiquitous on physical grounds, yet no clear signature of it has been found so far, possibly due to its transient nature and the lack of high-quality, broad-band X-ray spectra.