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Sample records for 50-70 mev bremsstrahlung

  1. Monte Carlo 20 and 45 MeV Bremsstrahlung and dose-reduction calculations

    SciTech Connect

    Goosman, D.R.

    1984-08-14

    The SANDYL electron-photon coupled Monte Carlo code has been compared with previously published experimental bremsstrahlung data at 20.9 MeV electron energy. The code was then used to calculate forward-directed spectra, angular distributions and dose-reduction factors for three practical configurations. These are: 20 MeV electrons incident on 1 mm of W + 59 mm of Be, 45 MeV electrons of 1 mm of W and 45 MeV electrons on 1 mm of W + 147 mm of Be. The application of these results to flash radiography is discussed. 7 references, 12 figures, 1 table.

  2. Validation of the GEANT4 simulation of bremsstrahlung from thick targets below 3 MeV

    NASA Astrophysics Data System (ADS)

    Pandola, L.; Andenna, C.; Caccia, B.

    2015-05-01

    The bremsstrahlung spectra produced by electrons impinging on thick targets are simulated using the GEANT4 Monte Carlo toolkit. Simulations are validated against experimental data available in literature for a range of energy between 0.5 and 2.8 MeV for Al and Fe targets and for a value of energy of 70 keV for Al, Ag, W and Pb targets. The energy spectra for the different configurations of emission angles, energies and targets are considered. Simulations are performed by using the three alternative sets of electromagnetic models that are available in GEANT4 to describe bremsstrahlung. At higher energies (0.5-2.8 MeV) of the impinging electrons on Al and Fe targets, GEANT4 is able to reproduce the spectral shapes and the integral photon emission in the forward direction. The agreement is within 10-30%, depending on energy, emission angle and target material. The physics model based on the Penelope Monte Carlo code is in slightly better agreement with the measured data than the other two. However, all models over-estimate the photon emission in the backward hemisphere. For the lower energy study (70 keV), which includes higher-Z targets, all models systematically under-estimate the total photon yield, providing agreement between 10% and 50%. The results of this work are of potential interest for medical physics applications, where knowledge of the energy spectra and angular distributions of photons is needed for accurate dose calculations with Monte Carlo and other fluence-based methods.

  3. Qualitative comparison of bremsstrahlung X-rays and 800 MeV protons for tomography of urania fuel pellets

    SciTech Connect

    Morris, C. L.; Bourke, M.; Byler, D. D.; Chen, C. F.; Hogan, G.; Hunter, J. F.; Kwiatkowski, K.; Mariam, F. G.; McClellan, K. J.; Merrill, F.; Morley, D. J.; Saunders, A.

    2013-02-15

    We present an assessment of x-rays and proton tomography as tools for studying the time dependence of the development of damage in fuel rods. We also show data taken with existing facilities at Los Alamos National Laboratory that support this assessment. Data on surrogate fuel rods have been taken using the 800 MeV proton radiography (pRad) facility at the Los Alamos Neutron Science Center (LANSCE), and with a 450 keV bremsstrahlung X-ray tomography facility. The proton radiography pRad facility at LANSCE can provide good position resolution (<70 {mu}m has been demonstrate, 20 {mu}m seems feasible with minor changes) for tomography on activated fuel rods. Bremsstrahlung x-rays may be able to provide better than 100 {mu}m resolution but further development of sources, collimation, and detectors is necessary for x-rays to deal with the background radiation for tomography of activated fuel rods.

  4. Qualitative comparison of bremsstrahlung X-rays and 800 MeV protons for tomography of urania fuel pellets

    SciTech Connect

    Morris, Christopher L.; Bourke, Mark A.; Byler, Darrin D.; Chen, Ching-Fong; Hogan, Gary E.; Hunter, James F.; Kwiatkowski, Kris K.; Mariam, Fesseha G.; McClellan, Kenneth J.; Merrill, Frank E.; Morley, Deborah J.; Saunders, Alexander

    2013-02-11

    We present an assessment of x-rays and proton tomography as tools for studying the time dependence of the development of damage in fuel rods. Also, we show data taken with existing facilities at Los Alamos National Laboratory that support this assessment. Data on surrogate fuel rods has been taken using the 800 MeV proton radiography (pRad) facility at the Los Alamos Neutron Science Center (LANSCE), and with a 450 keV bremsstrahlung X-ray tomography facility. The proton radiography pRad facility at LANSCE can provide good position resolution (<70 μm has been demonstrate, 20 μm seems feasible with minor changes) for tomography on activated fuel rods. Bremsstrahlung x-rays may be able to provide better than 100 μm resolution but further development of sources, collimation and detectors is necessary for x-rays to deal with the background radiation for tomography of activated fuel rods.

  5. Qualitative comparison of bremsstrahlung X-rays and 800 MeV protons for tomography of urania fuel pellets

    DOE PAGESBeta

    Morris, Christopher L.; Bourke, Mark A.; Byler, Darrin D.; Chen, Ching-Fong; Hogan, Gary E.; Hunter, James F.; Kwiatkowski, Kris K.; Mariam, Fesseha G.; McClellan, Kenneth J.; Merrill, Frank E.; et al

    2013-02-11

    We present an assessment of x-rays and proton tomography as tools for studying the time dependence of the development of damage in fuel rods. Also, we show data taken with existing facilities at Los Alamos National Laboratory that support this assessment. Data on surrogate fuel rods has been taken using the 800 MeV proton radiography (pRad) facility at the Los Alamos Neutron Science Center (LANSCE), and with a 450 keV bremsstrahlung X-ray tomography facility. The proton radiography pRad facility at LANSCE can provide good position resolution (<70 μm has been demonstrate, 20 μm seems feasible with minor changes) for tomographymore » on activated fuel rods. Bremsstrahlung x-rays may be able to provide better than 100 μm resolution but further development of sources, collimation and detectors is necessary for x-rays to deal with the background radiation for tomography of activated fuel rods.« less

  6. Thick target bremsstrahlung spectra for 1.00-, 1.25-, and 1.40-Mev electrons

    USGS Publications Warehouse

    Miller, W.; Motz, J.W.; Cialella, C.

    1954-01-01

    The spectrum of radiation produced by 1.0-, 1.25-, and 1.40-Mev electrons incident on a thick tungsten target was measured at 0A????and 90A????with the incident beam by a method involving the magnetic analysis of Compton electrons. The effects of electron scattering and energy loss in the target preclude any simple interpretation of this data to yield a differential bremsstrahlung cross section. However, an estimate of the spectra to be expected at 0A????and 90A????was obtained by combining the Sauter expression for the bremsstrahlung cross section with the available information on electron scatter and energy loss in the target and backscatter from the target. The reliability of the estimate is limited because the Sauter formula was calculated by using the Born approximation, the electron scattering calculations are applicable to an infinite medium only, and the backscatter was estimated empirically from Bothe's experimental data which were obtained with lower energy electrons (370 kev). Furthermore electron energy straggling was neglected. Nevertheless, the predicted spectral shapes at 0A????and 90A????and the relative intensities at these two angles are in qualitative agreement with the measured values. The absolute magnitudes of the measured intensities at both angles are about a factor of two greater than the predicted values. ?? 1954 The American Physical Society.

  7. Higher-order corrections to electron-nucleus bremsstrahlung cross sections above a few MeV

    NASA Astrophysics Data System (ADS)

    Mangiarotti, A.; Martins, M. N.

    2016-08-01

    Despite the fact that the first calculations of nuclear bremsstrahlung cross sections were performed for relativistic electrons more than 80 years ago by Sauter, Bethe and Heitler, and Racah, a fully satisfactory solution to this problem is still missing up to the present day. Numerical approaches are impractical for electrons with energies above a few MeV because they require a prohibitively large number of partial waves. Analytic formulae need to describe simultaneously and accurately the interaction with the Coulomb field of the nucleus and the screening effect of the atomic electrons. In the present paper, a state-of-the-art analytic calculation will be discussed. In particular, higher-order corrections to the interaction with the Coulomb field of the nucleus, a subject seldom tackled in the past, are included and compared extensively with published data. The emerged difficulties will be highlighted, but unfortunately they can be overcome only with future large coordinated theoretical and experimental efforts.

  8. Production of isotopes and isomers with irradiation of Z = 47–50 targets by 23-MeV bremsstrahlung

    SciTech Connect

    Karamian, S. A.; Carroll, J. J.; Aksenov, N. V.; Albin, Yu. A.; Belov, A. G.; Bozhikov, G. A.; Dmitriev, S. N.; Starodub, G. Ya.

    2015-09-15

    The irradiations of Ag to Sn targets by bremsstrahlung generated with 23-MeV electron beams are performed at the MT-25 microtron. Gamma spectra of the induced activities have been measured and the yields of all detected radionuclides and isomers are carefully measured and analyzed. A regular dependence of yields versus changed reaction threshold is confirmed. Many isomers are detected and the suppression of the production probability is observed with growing product spin. Special peculiarities for the isomer-to-ground state ratios were deduced for the {sup 106m}Ag, {sup 108m}Ag, {sup 113m}In, {sup 115m}In, and {sup 123m}Sn isomers. The production of such nuclides as {sup 108m}Ag, {sup 115m}In, {sup 117g}In, and {sup 113m}Cd is of interest for applications, especially when economic methods are available.

  9. Accuracy evaluation of a Compton X-ray spectrometer with bremsstrahlung X-rays generated by a 6 MeV electron buncha)

    NASA Astrophysics Data System (ADS)

    Kojima, Sadaoki; Arikawa, Yasunobu; Nishimura, Yasuhiko; Togawa, Hiromi; Zhang, Zhe; Ikenouchi, Takahito; Ozaki, Tetsuo; Morace, Alessio; Nagai, Takahiro; Abe, Yuki; Sakata, Shouhei; Inoue, Hiroaki; Utsugi, Masaru; Nakai, Mitsuo; Nishimura, Hiroaki; Shiraga, Hiroyuki; Kato, Ryukou; Fujioka, Shinsuke; Azechi, Hiroshi

    2014-11-01

    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.

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

    SciTech Connect

    Kojima, Sadaoki 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; Nishimura, Yasuhiko; Togawa, Hiromi; Ozaki, Tetsuo; Kato, Ryukou

    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.

  11. Polarized-target asymmetry in pion-proton bremsstrahlung at 298 MeV

    SciTech Connect

    Bosshard, A.; Amsler, C.; Bistirlich, J.A.; van den Brandt, B.; Crowe, K.M.; Doebeli, M.; Doser, M.; Haddock, R.P.; Konter, J.A.; Ljungfelt, S.; Loude, J.F.; Mango, S.; Meyer, C.A.; Perroud, J.P.; Riedlberger, J.; Renker, D.; Schaad, M.; Sober, D.I.; Truoel, P.; Weymuth, P. Lawrence Berkeley Laboratory, University of California at Berkeley, Berkeley California 94720 Paul Scherrer Institut, 5232 Villigen, Paul Scherrer Institut, Department of Physics, University of California at Los Angeles, Los Angeles, California 90024 Institut de Physique Nucleaire, Universite de Lausanne, 1015 Lausanne, Department of Physics, Catholic University of America, Washington, D.C. 10024 )

    1990-05-28

    First data are presented for the polarized-target asymmetry in the reaction {pi}{sup +}{ital p}{r arrow}{pi}{sup +}{ital p}{gamma} at an incident pion energy of 298 MeV. The geometry was chosen to maximize the sensitivity to the radiation of the magnetic dipole moment {mu}{sub {Delta}} of the {Delta}{sup ++}(1232 MeV). A fit of the asymmetry in the cross section {ital d}{sup 5}{sigma}/{ital d}{Omega}{sub {pi}} {ital d}{Omega}{sub {gamma}} {ital dk} as a function of the photon energy {ital k} to predictions from a recent isobar-model calculation with {mu}{sub {Delta}} as the only free parameter yields {mu}{sub {Delta}}=1.64({plus minus}0.19exp{Delta},{plus minus}0.14 theor){mu}{sub {ital p}}. Though this value agrees with bag-model corrections to the SU(6) prediction {mu}{sub {Delta}}=2{mu}{sub {ital p}}, further clarifications on the model dependence of the result are needed, in particular since the isobar model fails to describe both the cross section and the asymmetry at the highest photon energies.

  12. Angular distributions of absorbed dose of Bremsstrahlung and secondary electrons induced by 18-, 28- and 38-MeV electron beams in thick targets.

    PubMed

    Takada, Masashi; Kosako, Kazuaki; Oishi, Koji; Nakamura, Takashi; Sato, Kouichi; Kamiyama, Takashi; Kiyanagi, Yoshiaki

    2013-03-01

    Angular distributions of absorbed dose of Bremsstrahlung photons and secondary electrons at a wide range of emission angles from 0 to 135°, were experimentally obtained using an ion chamber with a 0.6 cm(3) air volume covered with or without a build-up cap. The Bremsstrahlung photons and electrons were produced by 18-, 28- and 38-MeV electron beams bombarding tungsten, copper, aluminium and carbon targets. The absorbed doses were also calculated from simulated photon and electron energy spectra by multiplying simulated response functions of the ion chambers, simulated with the MCNPX code. Calculated-to-experimental (C/E) dose ratios obtained are from 0.70 to 1.57 for high-Z targets of W and Cu, from 15 to 135° and the C/E range from 0.6 to 1.4 at 0°; however, the values of C/E for low-Z targets of Al and C are from 0.5 to 1.8 from 0 to 135°. Angular distributions at the forward angles decrease with increasing angles; on the other hand, the angular distributions at the backward angles depend on the target species. The dependences of absorbed doses on electron energy and target thickness were compared between the measured and simulated results. The attenuation profiles of absorbed doses of Bremsstrahlung beams at 0, 30 and 135° were also measured.

  13. Characterisation of a MeV Bremsstrahlung x-ray source produced from a high intensity laser for high areal density object radiography

    SciTech Connect

    Courtois, C.; Compant La Fontaine, A.; Bazzoli, S.; Bourgade, J. L.; Gazave, J.; Lagrange, J. M.; Landoas, O.; Dain, L. Le; Pichoff, N.; Edwards, R.; Aedy, C.; Mastrosimone, D.; Pien, G.; Stoeckl, C.

    2013-08-15

    Results of an experiment to characterise a MeV Bremsstrahlung x-ray emission created by a short (<10 ps) pulse, high intensity (1.4 × 10{sup 19} W/cm{sup 2}) laser are presented. X-ray emission is characterized using several diagnostics; nuclear activation measurements, a calibrated hard x-ray spectrometer, and dosimeters. Results from the reconstructed x-ray energy spectra are consistent with numerical simulations using the PIC and Monte Carlo codes between 0.3 and 30 MeV. The intense Bremsstrahlung x-ray source is used to radiograph an image quality indicator (IQI) heavily filtered with thick tungsten absorbers. Observations suggest that internal features of the IQI can be resolved up to an external areal density of 85 g/cm{sup 2}. The x-ray source size, inferred by the radiography of a thick resolution grid, is estimated to be approximately 400 μm (full width half maximum of the x-ray source Point Spread Function)

  14. Measurement of isomeric-yield ratios of 109m,gPd and 115m,gCd with 50-, 60-, and 70-MeV bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Rahman, Md. Shakilur; Lee, Manwoo; Kim, Kyung-Sook; Kim, Guinyun; Kim, Eunae; Cho, Moo-Hyun; Shvetshov, Valery; Khue, Pham Duc; Van Do, Nguyen

    2012-04-01

    The isomeric-yield ratios of 109m,gPd and 115m,gCd were measured by the activation method with uncollimated bremsstrahlung beams of 50-, 60-, and 70-MeV generated from an electron linear accelerator at Pohang Accelerator Laboratory. The induced activities in the irradiated foils were measured by the high-resolution γ-ray spectrometric system consisting of a high-purity germanium detector and a multichannel analyzer. The obtained isomeric-yield ratios in the formation of 109m,gPd and 115m,gCd are compared with the corresponding values found in the other experiments and the calculated values based on the statistical model code TALYS. The present results for 109m,gPd and 115m,gCd in this energy region are the first measurement.

  15. Measurement of isomeric ratios for 89g,mZr, 91g,mMo, and 97g,mNb in the bremsstrahlung end-point energies of 16 and 45-70 MeV

    NASA Astrophysics Data System (ADS)

    Naik, H.; Kim, G. N.; Schwengner, R.; Kim, K.; Zaman, M.; Yang, S. C.; Shin, S. G.; Kye, Y.-U.; Massarczyk, R.; John, R.; Junghans, A.; Wagner, A.; Goswami, A.; Cho, M.-H.

    2016-03-01

    The independent isomeric yield ratios of 89g,mZr from the natZr(γ,xn) reactions and those of 91g, mMo and 97g,mNb from the natMo(γ,x) reactions with the bremsstrahlung end-point energy of 45-70 MeV were determined by an off-line γ-ray spectrometric technique using the 100 MeV electron linac at the Pohang Accelerator Laboratory, Korea. The isomeric yield ratios of 89g,mZr and 97g,mNb from the natZr(γ, xn) and natMo(γ,x) reactions at the bremsstrahlung end-point energy of 16MeV were also determined by the same technique using the 20MeV electron linac at Helmholtz-Zentrum Dresden-Rossendorf, Germany. The measured isomeric yield ratios of 89g,mZr, 91g,mMo, and 97g,mNb were compared with literature data to examine the role of the Giant Dipole Resonance (GDR). The isomeric yield ratios of the 89g,mZr, 91g,mMo, and 97g,mNb from the above reactions were also calculated by using the computer code TALYS 1.6 and compared with the experimental data to examine the validity of the theoretical model for independent isomeric yield ratio calculations.

  16. 31 CFR 50.70 - Mandatory and discretionary recoupment.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... recoupment. 50.70 Section 50.70 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Recoupment and Surcharge Procedures § 50.70 Mandatory and discretionary..., such Federal Terrorism Policy Surcharges as needed to recover 133 percent of the mandatory...

  17. 31 CFR 50.70 - Mandatory and discretionary recoupment.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... recoupment. 50.70 Section 50.70 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM RISK INSURANCE PROGRAM Recoupment and Surcharge Procedures § 50.70 Mandatory and discretionary..., such Federal Terrorism Policy Surcharges as needed to recover 133 percent of the mandatory...

  18. Bremsstrahlung Measurements at PBFA Z

    NASA Astrophysics Data System (ADS)

    Rochau, G. A.; Derzon, M. S.; Fehl, D.; Mock, R.; Ruiz, C.; Sweeney, M. A.; Struve, K.; Lazier, S.; Cooper, G.

    1997-11-01

    The PBFA Z accelerator at Sandia National Laboratories demonstrates z-pinch implosions capable of producing 1.8 MJ of soft x-rays. Associated with the power flow on PBFA Z is a bremsstrahlung background produced by electrons with endpoint energies greater than 2 MeV. In this presentation we present time-integrated images of the bremsstrahlung source, the measured bremsstrahlung spectrum both on-axis and side-on with respect to the target, and the bremsstrahlung background intensity as a function of azimuthal angle over the target. Measurements indicate that this background may be isotropic making it less of a concern when fielding diagnostics than previously considered. Additionally, electron losses, which have critical effects on power flow, are estimated with the Screamer circuit code and compared to the losses as determined by unfolding the measured bremsstrahlung field. Disagreements between these estimates are presented and discussed.

  19. Photo-neutron reaction cross-sections for natMo in the bremsstrahlung end-point energies of 12-16 and 45-70 MeV

    NASA Astrophysics Data System (ADS)

    Naik, H.; Kim, G. N.; Kapote Noy, R.; Schwengner, R.; Kim, K.; Zaman, M.; Shin, S. G.; Gey, Y.; Massarczyk, R.; John, R.; Junghans, A.; Wagner, A.; Cho, M.-H.

    2016-07-01

    The natMo( γ, xn)90, 91, 99Mo reaction cross-sections were experimentally determined for the bremsstrahlung end-point energies of 12, 14, 16, 45, 50, 55, 60 and 70MeV by activation and off-line γ -ray spectrometric technique and using the 20MeV electron linac (ELBE) at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The natMo( γ, xn)88, 89, 90, 91, 99Mo reaction cross-sections as a function of photon energy were also calculated using the computer code TALYS 1.6. The flux-weighted average cross-sections were obtained from the literature data and the calculated values of TALYS based on mono-energetic photons and are found to be in general agreement with the present results. The flux-weighted average experimental and theoretical cross-sections for the natMo( γ, xn)88, 89, 90, 91, 99Mo reactions increase with the bremsstrahlung end-point energy, which indicates the role of excitation energy. After a certain energy, the individual natMo( γ, xn) reaction cross-sections decrease with the increase of bremsstrahlung energy due to opening of other reactions, which indicates sharing of energy in different reaction channels. The 100Mo( γ, n) reaction cross-section is important for the production of 99Mo , which is a probable alternative to the 98Mo(n, γ) and 235U(n, f ) reactions.

  20. Measurement of flux-weighted average cross-sections and isomeric yield ratios for 103Rh(γ,xn) reactions in the bremsstrahlung end-point energies of 55 and 60 MeV

    NASA Astrophysics Data System (ADS)

    Shakilur Rahman, Md.; Kim, Kwangsoo; Kim, Guinyun; Naik, Haladhara; Nadeem, Muhammad; Thi Hien, Nguyen; Shahid, Muhammad; Yang, Sung-Chul; Cho, Young-Sik; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun; Woo Lee, Man; Kang, Yeong-Rok; Yang, Gwang-Mo; Ro, Tae-Ik

    2016-07-01

    We measured the flux-weighted average cross-sections and the isomeric yield ratios of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions with the bremsstrahlung end-point energies of 55 and 60MeV by the activation and the off-line γ-ray spectrometric technique, using the 100MeV electron linac at the Pohang Accelerator Laboratory (PAL), Korea. The flux-weighted average cross-sections were calculated by using the computer code TALYS 1.6 based on mono-energetic photons, and compared with the present experimental data. The flux-weighted average cross-sections of 103Rh( γ, xn) reactions in intermediate bremsstrahlung energies are the first time measurement and are found to increase from their threshold value to a particular value, where the other reaction channels open up. Thereafter, it decreases with bremsstrahlung energy due to its partition in different reaction channels. The isomeric yield ratios (IR) of 99m, g, 100m, g, 101m, g, 102m, gRh in the 103Rh( γ, xn) reactions from the present work were compared with the literature data in the 103Rh(d, x), 102-99Ru(p, x) , 103Rh( α, αn) , 103Rh( α, 2p3n) , 102Ru(3He, x), and 103Rh( γ, xn) reactions. It was found that the IR values of 102, 101, 100, 99Rh in all these reactions increase with the projectile energy, which indicates the role of excitation energy. At the same excitation energy, the IR values of 102, 101, 100, 99Rh are higher in the charged particle-induced reactions than in the photon-induced reaction, which indicates the role of input angular momentum.

  1. 31 CFR 50.70 - Mandatory and discretionary recoupment.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... recoupment. 50.70 Section 50.70 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM..., such Federal Terrorism Policy Surcharges as needed to recover 133 percent of the mandatory recoupment... Federal Terrorism Policy Surcharge based on the factors set forth in section 103(e)(7)(D) of the Act....

  2. 31 CFR 50.70 - Mandatory and discretionary recoupment.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... recoupment. 50.70 Section 50.70 Money and Finance: Treasury Office of the Secretary of the Treasury TERRORISM..., such Federal Terrorism Policy Surcharges as needed to recover 133 percent of the mandatory recoupment... Federal Terrorism Policy Surcharge based on the factors set forth in section 103(e)(7)(D) of the Act....

  3. Photoexcitation of the high-spin J=8 isomer in (176)Yb using 8.5MeV end-point energy Bremsstrahlung.

    PubMed

    Tickner, James

    2016-04-01

    Excitation of the 1049.8keV isomeric state (t1/2=11.4s, spin difference between ground and isomeric states ΔJ=8) in (176)Yb using Bremsstrahlung radiation is observed for the first time. In contrast to the photoexcitation of isomeric states in other nuclei with lower spin differences, where effective integrated cross-sections are of order tens to hundreds of barneV, an integrated cross-section of just 0.0484±0.066barneV is observed for (176)Yb. PMID:26752318

  4. Measured bremsstrahlung photonuclear production of 99Mo ((99m)Tc) with 34 MeV to 1.7 GeV electrons.

    PubMed

    Roberts, A D; Geddes, C G R; Matlis, N; Nakamura, K; O'Neil, J P; Shaw, B H; Steinke, S; van Tilborg, J; Leemans, W P

    2015-02-01

    (99)Mo photonuclear yield was measured using high-energy electrons from Laser Plasma Accelerators and natural molybdenum. Spectroscopically resolved electron beams allow comparisons to Monte Carlo calculations using known (100)Mo(γ,n)(99)Mo cross sections. Yields are consistent with published low-energy data, and higher energy data are well predicted from the calculations. The measured yield is (15±2)×10(-5) atoms/electron (0.92±0.11 GBq/μA) for 25 mm targets at 33.7 MeV, rising to (1391±20)×10(-5) atoms/electron (87±2 GBq/μA) for 54 mm/ 1.7 GeV, with peak power-normalized yield at 150 MeV.

  5. Properties of carbon-based structures synthesized in nuclear reactions induced by bremsstrahlung γ quanta with threshold energy of 10 MeV at helium pressure of 1.1 kbar

    NASA Astrophysics Data System (ADS)

    Didyk, A. Yu.; Wiśniewski, R.

    2016-07-01

    Helium gas with an initial pressure of about 1.1 kbar inside a high-pressure chamber (HeHPC) has been irradiated by bremsstrahlung γ quanta with a threshold energy of 10 MeV for 1.0 × 105 s produced by an electron-beam current of 22-24 μA. After opening the HeHPC, the residual pressure of helium is equal to 430 bar. Synthesized black foils with a variety of other objects are found inside the HeHPC. They are located on the inner surfaces of the reaction chamber made of high-purity copper (99.99%), the entrance the window of γ quanta made of beryllium bronze and a copper container of nuclear and chemical reaction products. Elemental analysis with the use of scanning electron microscopy and X-ray microprobe analysis has revealed that the foils contain predominantly carbon and small quantities of other elements from carbon to iron. The results are in good agreement with the cycle of investigations of the authors devoted to the γ-quanta irradiation of dense hydrogen and helium gases in the presence (absence) of metals in a reaction chamber.

  6. Electroweak bremsstrahlung from neutron-neutron scattering

    SciTech Connect

    Li Yi; Liou, M. K.; Schreiber, W. M.

    2009-09-15

    Background: Nucleon-nucleon (NN) bremsstrahlung processes NN{gamma} (nn{gamma}, np{gamma}, and pp{gamma}) have been extensively investigated. Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering NN{nu}{nu} (nn{nu}{nu}, np{nu}{nu}, and pp{nu}{nu}) have recently attracted attention in studies of neutrino emission in neutron stars. The calculated NN{nu}{nu} cross sections (or emissivities) are found to be sensitive to the two-nucleon dynamical model used in the calculations. Purpose and Method: A realistic one-boson-exchange (ROBE) model for NN interactions is used to construct the electroweak bremsstrahlung amplitudes using the well-known nucleon electromagnetic and weak interaction vertices. The constructed nn{gamma} and nn{nu}{nu} amplitudes are investigated by applying them to calculate nn{gamma} and nn{nu}{nu} cross sections, respectively. Results: (i) The 190-MeV ROBE nn{gamma} cross sections agree well with those calculated using the TuTts amplitude, but they are in disagreement with those calculated using the Low amplitude. (ii) The calculated nn{nu}{nu} cross sections using the ROBE amplitude at the neutrino-pair energy {omega} = 1 MeV are in quantitative agreement with those calculated by Timmermans et al.[Phys. Rev. C 65, 064007 (2002)], who used the leading-order term of the soft neutrino-pair bremsstrahlung amplitude. Conclusions: The nn{gamma} amplitude in the ROBE approach, which obeys the soft-photon theorem, has a predictive power similar to that of the TuTts amplitude. The nn{nu}{nu} amplitude in the ROBE approach, which is consistent with the soft neutrino-pair bremsstrahlung theorem, has a predictive power similar to that of the soft neutrino-pair bremsstrahlung amplitude of Timmermans et al. in the low neutrino-pair energy region.

  7. Bremsstrahlung from relativistic heavy ions in matter

    SciTech Connect

    Soerensen, Allan H.

    2010-02-15

    The emission of electromagnetic radiation by relativistic bare heavy ions penetrating ordinary matter is investigated. Our main aim is to determine the bremsstrahlung which we define as the radiation emitted when the projectile does not break up. It pertains to collisions without nuclear contact ('ultraperipheral collisions'). Requirement of coherent action of the nucleons in order to keep the penetrating projectile intact limits bremsstrahlung to relatively soft photons. The spectrum shows a resonance structure with peak position near 2{gamma} times the position of the giant dipole resonance, that is, near 25{gamma} MeV for a lead ion ({gamma}{identical_to}E/Mc{sup 2} is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak. As a result of its relative softness, bremsstrahlung never dominates the energy-loss process for heavy ions. As to the emission of electromagnetic radiation in collisions with nuclear break-up, it appears modest when pertaining to incoherent action of the projectile nucleons in noncontact collisions. In collisions with nuclear contact, though, substantial radiation is emitted. It overshoots the bremsstrahlung. However, despite the violence of contact events, the associated photon emission only exceeds the radiation from a hypothetical structureless pointlike nucleus [emitted energy per unit photon-energy interval essentially constant up to ({gamma}-1)Mc{sup 2}] at relatively low photon energies (for lead roughly below 0.2{gamma} GeV, a limit which is about an order of magnitude above the position of the bremsstrahlung peak). Results are presented for bare lead ions penetrating a solid lead target at energies of 158 GeV/n ({gamma}=170) and beyond.

  8. Bremsstrahlung from relativistic heavy ions in matter

    NASA Astrophysics Data System (ADS)

    Sørensen, Allan H.

    2010-02-01

    The emission of electromagnetic radiation by relativistic bare heavy ions penetrating ordinary matter is investigated. Our main aim is to determine the bremsstrahlung which we define as the radiation emitted when the projectile does not break up. It pertains to collisions without nuclear contact (“ultraperipheral collisions”). Requirement of coherent action of the nucleons in order to keep the penetrating projectile intact limits bremsstrahlung to relatively soft photons. The spectrum shows a resonance structure with peak position near 2γ times the position of the giant dipole resonance, that is, near 25γ MeV for a lead ion (γ≡E/Mc2 is the Lorentz factor of the projectile of energy E and mass M). The maximum exceeds the bremsstrahlung from a hypothetical structureless, pointlike particle of the same charge and mass as the incoming nucleus, but rapid depletion follows on the high-energy side of the peak. As a result of its relative softness, bremsstrahlung never dominates the energy-loss process for heavy ions. As to the emission of electromagnetic radiation in collisions with nuclear break-up, it appears modest when pertaining to incoherent action of the projectile nucleons in noncontact collisions. In collisions with nuclear contact, though, substantial radiation is emitted. It overshoots the bremsstrahlung. However, despite the violence of contact events, the associated photon emission only exceeds the radiation from a hypothetical structureless pointlike nucleus [emitted energy per unit photon-energy interval essentially constant up to (γ-1)Mc2] at relatively low photon energies (for lead roughly below 0.2γ GeV, a limit which is about an order of magnitude above the position of the bremsstrahlung peak). Results are presented for bare lead ions penetrating a solid lead target at energies of 158 GeV/n (γ=170) and beyond.

  9. 46 CFR 151.50-70 - Cargoes requiring inhibition or stabilization.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Cargoes requiring inhibition or stabilization. 151.50-70 Section 151.50-70 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS... requiring inhibition or stabilization. When table 151.05 refers to this section, that cargo must be—...

  10. Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeV.

    PubMed

    Sakata, S; Arikawa, Y; Kojima, S; Ikenouchi, T; Nagai, T; Abe, Y; Inoue, H; Morace, A; Utsugi, M; Kato, R; Nishimura, H; Nakai, M; Shiraga, H; Fujioka, S; Azechi, H

    2014-11-01

    A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (Ne = 1.0 × 10(-6) C, Ee = 16 ± 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%-70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Δhν/hν) of about 15%. Quantum efficiency of this spectrometer was designed to be 10(-7), 10(-4), 10(-5), respectively, for 2-10, 11-15, and 15-25 MeV of photon energy ranges.

  11. Relativistic electron transport and bremsstrahlung production in solar flares

    NASA Astrophysics Data System (ADS)

    Miller, James A.; Ramaty, Reuven

    1989-09-01

    A Monte Carlo simulation of ultrarelativistic electron transport in solar flare magnetic loops has been developed. It includes Coulomb, synchrotron, and bremsstrahlung energy losses; pitch-angle scattering by Alfven and whistler turbulence in the coronal region of the loop; and magnetic mirroring in the converging magnetic flux tubes beneath the transition region. Depth distributions, time profiles, energy spectra, and angular distributions of the resulting bremsstrahlung emission are calculated. It is found that both the preferential detection of solar flares with greater than 10 MeV emission near the limb of the sun and the observation of ultrarelativistic electron bremsstrahlung from flares on the disk are consequences of the loop transport model. The declining portions of the observed time profiles of greater than 10 MeV emission from solar flares can also be accounted for, and it is proposed that these portions are determined by transport and not acceleration.

  12. Runaway electrons and Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Helander, Per

    2016-09-01

    If an electric field is applied to a plasma, it causes ‘runaway’ acceleration of some electrons—a phenomenon that has been known for almost a century. A paper by Embréus et al (2016 New J. Phys. 18 093023) calculates how the emission of Bremsstrahlung affects the upper end of the energy spectrum of these electrons, and finds that it is important to carefully account for finite energy of the emitted photons.

  13. Bremsstrahlung source term estimation for high energy electron accelerators

    NASA Astrophysics Data System (ADS)

    Nayak, M. K.; Sahu, T. K.; Nair, H. G.; Nandedkar, R. V.; Bandyopadhyay, Tapas; Tripathi, R. M.; Hannurkar, P. R.; Sharma, D. N.

    2015-08-01

    Thick target bremsstrahlung source term for 450 MeV and 550 MeV electrons are experimentally determined using booster synchrotron of Indus facility at Raja Ramanna Centre for Advanced Technology, Indore, India. The source term is also simulated using EGSnrc Monte Carlo code. Results from experiment and simulation are found to be in very good agreement. Based on the agreement between experimental and simulated data, the source term is determined up to 3000 MeV by simulation. The paper also describes the studies carried out on the variation of source term when a thin target is considered in place of a thick target, used in earlier studies.

  14. Inverse problem for Bremsstrahlung radiation

    SciTech Connect

    Voss, K.E.; Fisch, N.J.

    1991-10-01

    For certain predominantly one-dimensional distribution functions, an analytic inversion has been found which yields the velocity distribution of superthermal electrons given their Bremsstrahlung radiation. 5 refs.

  15. A Bremsstrahlung spectrometer using k-edge and differential filters with image plate dosimeters

    SciTech Connect

    Chen, C. D.; Porkolab, M.; King, J. A.; Beg, F. N.; Key, M. H.; Chen, H.; Mackinnon, A. J.; MacPhee, A. G.; Patel, P. K.; Akli, K. U.; Stephens, R. B.; Freeman, R. R.; Link, A.; Van Woerkom, L. D.

    2008-10-15

    A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with image plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code INTEGRATED TIGER SERIES 3.0 and the dosimeters calibrated with radioactive sources. An electron distribution with a slope temperature of 1.3 MeV is inferred from the Bremsstrahlung spectra.

  16. A Bremsstrahlung Spectrometer using k-edge and Differential Filters with Image plate dosimeters

    SciTech Connect

    Chen, C; Mackinnon, A; Beg, F; Chen, H; Key, M; King, J A; Link, A; MacPhee, A; Patel, P; Porkolab, M; Stephens, R; VanWoerkom, L; Akli, K; Freeman, R

    2008-05-02

    A Bremsstrahlung spectrometer using k-edge and differential filtering has been used with Image Plate dosimeters to measure the x-ray fluence from short-pulse laser/target interactions. An electron spectrometer in front of the Bremsstrahlung spectrometer deflects electrons from the x-ray line of sight and simultaneously measures the electron spectrum. The response functions were modeled with the Monte Carlo code Integrated Tiger Series 3.0 and the dosimeters calibrated with radioactive sources. Electron distributions with slope temperatures in the MeV range are inferred from the Bremsstrahlung spectra.

  17. Bremsstrahlung converter debris shields: test and analysis

    SciTech Connect

    Reedy, E.D. Jr.; Perry, F.C.

    1983-10-01

    Electron beam accelerators are commonly used to create bremsstrahlung x-rays for effects testing. Typically, the incident electron beam strikes a sandwich of three materials: (1) a conversion foil, (2) an electron scavenger, and (3) a debris shield. Several laboratories, including Sandia National Laboratories, are developing bremsstrahlung x-ray sources with much larger test areas (approx. 200 to 500 cm/sup 2/) than ever used before. Accordingly, the debris shield will be much larger than before and subject to loads which could cause shield failure. To prepare for this eventuality, a series of tests were run on the Naval Surface Weapons Center's Casino electron beam accelerator (approx. 1 MeV electrons, 100 ns FWHM pulse, 45 kJ beam energy). The primary goal of these tests was to measure the stress pulse which loads a debris shield. These measurements were made with carbon gages mounted on the back of the converter sandwich. At an electron beam fluence of about 1 kJ/cm/sup 2/, the measured peak compressive stress was typically in the 1 to 2 kbar range. Measured peak compressive stress scaled in a roughly linear manner with fluence level as the fluence level was increased to 10 kJ/cm/sup 2/. The duration of the compressive pulse was on the order of microseconds. In addition to the stress wave measurements, a limited number of tests were made to investigate the type of damage generated in several potential shield materials.

  18. Coherent bremsstrahlung used for digital subtraction angiography

    NASA Astrophysics Data System (ADS)

    Überall, Herbert

    2007-05-01

    Digital subtraction angiography (DSA), also known as Dichromography, using synchrotron radiation beams has been developed at Stanford University (R. Hofstadter) and was subsequently taken over at the Brookhaven Synchrotron and later at Hamburg (HASYLAB) [see, e.g., W.R. Dix, Physik in unserer Zeit. 30 (1999) 160]. The imaging of coronary arteries is carried out with an iodine-based contrast agent which need not be injected into the heart. The radiation must be monochromatized and is applied above and below the K-edge of iodine (33.16 keV), with a subsequent digital subtraction of the two images. Monochromatization of the synchrotron radiation causes a loss of intensity of 10 -3. We propose instead the use of coherent bremsstrahlung [see, e.g., A.W. Saenz and H. Uberall, Phys. Rev. B25 (1982) 448] which is inherently monochromatic, furnishing a flux of 10 12 photon/sec. This requires a 10-20 MeV electron linac which can be obtained by many larger hospitals, eliminating the scheduling problems present at synchrotrons. The large, broad incoherent bremsstrahlung background underlying the monochromatic spike would lead to inadmissible overexposure of the patient. This problem can be solved with the use of Kumakhov's capillary optics [see e.g., S.B.Dabagov, Physics-Uspekhi 46 (2003) 1053]: the low-energy spiked radiation can be deflected towards the patient, while the higher energy incoherent background continues forward, avoiding the patient who is placed several meters from the source.

  19. Enhancing Bremsstrahlung Radiation using Front Surface Target Structures

    NASA Astrophysics Data System (ADS)

    Jiang, Sheng; Krygier, Andrew; Schumacher, Douglass; Freeman, Richard; Akli, Kramer

    2014-10-01

    X-ray or γ-ray sources generated by laser solid interactions have many potential applications in different fields including X-ray radiography, pair production and photonuclear physics. Recent studies with 3D PIC modeling have shown that large scale front-surface target structures can significantly increase the energy and narrow the angular distribution of hot electrons compared to that for a regular flat target. These characteristics of electrons are crucial for further Bremsstrahlung production using a high-Z converter target. The corresponding Bremsstrahlung radiation covers a wide energy range and can be as high as 100 MeV. By performing the Monte-Carlo simulations we find that the peak γ-ray brightness is 6 . 0 * 1019 s-1 mm-2 mrad-2 at 10 MeV and 1 . 4 * 1019 s-1 mm-2 mrad-2 at 100 MeV (0.1% bandwidth), which is comparable to other tunable γ-ray sources. The brightness for high energy γ-rays (>50 MeV) is one or a few orders of magnitude higher using the structured target than the flat target. Simulation and preliminary experimental results will be presented. This work is supported by AFOSR Young Investigator Program and NNSA with computing time from the Ohio Supercomputer Center.

  20. Analytic approximate radiation effects due to Bremsstrahlung

    SciTech Connect

    Ben-Zvi I.

    2012-02-01

    The purpose of this note is to provide analytic approximate expressions that can provide quick estimates of the various effects of the Bremsstrahlung radiation produced relatively low energy electrons, such as the dumping of the beam into the beam stop at the ERL or field emission in superconducting cavities. The purpose of this work is not to replace a dependable calculation or, better yet, a measurement under real conditions, but to provide a quick but approximate estimate for guidance purposes only. These effects include dose to personnel, ozone generation in the air volume exposed to the radiation, hydrogen generation in the beam dump water cooling system and radiation damage to near-by magnets. These expressions can be used for other purposes, but one should note that the electron beam energy range is limited. In these calculations the good range is from about 0.5 MeV to 10 MeV. To help in the application of this note, calculations are presented as a worked out example for the beam dump of the R&D Energy Recovery Linac.

  1. Applicability study on existing dosimetry systems to high-power Bremsstrahlung irradiation

    NASA Astrophysics Data System (ADS)

    Mehta, Kishor; Kojima, Takuji; Sunaga, Hiromi

    2003-12-01

    Applicability of the existing dosimetry systems to high-power Bremsstrahlung irradiation was investigated through a dose intercomparison study, where several dosimeters were irradiated in the dose range 4-12 kGy in identical polyethylene phantoms in a Bremsstrahlung beam obtained from a 5-MeV electron accelerator. Included in the study were alanine dosimeters molded by three different binders, three types of liquid dosimeters—ceric-cerous, dichromate and ethanol-chlorobenzen (ECB), and glutamine powder. The dosimeter responses for Bremsstrahlung radiation were analyzed at the issuing laboratories, and the dose values determined using calibration based on cobalt-60 gamma-ray irradiation. Dose values for all the three dose levels for all dosimetry systems were in good agreement—better than 3%. The results of the study demonstrate that these existing dosimetry systems have a potential for application to high-power Bremsstrahlung irradiation.

  2. Proton-proton bremsstrahlung calculation: Comparison with recent high-precision experimental results

    SciTech Connect

    Li Yi; Liou, M.K.; Schreiber, W.M.

    2005-08-01

    Proton-proton bremsstrahlung cross sections and analyzing powers have been calculated at 190 MeV by using a one-boson-exchange model. The results are compared with the recently published high-precision Kernfysisch-Versneller-Instituut (KVI) data. Satisfactory agreement between theory and experiment has been found.

  3. /ital P/-odd asymmetry of the cross section for bremsstrahlung of longitudinally polarized electrons by nuclei

    SciTech Connect

    Safin, M. Y.

    1988-12-01

    The differential cross section and the right--left asymmetry are calculated for bremsstrahlung of longitudinally polarized electrons by nuclei, with account taken of the interaction of weak neutral currents. It is shown that at electron energies /ital E//lt/200 MeV the asymmetry of bremsstrahlung by /sup 181/Ta and /sup 11/B nuclei does not exceed 2/center dot/10/sup /minus/9/.

  4. Ultrahigh-intensity inverse bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Kostyukov, I. Yu.; Rax, J.-M.

    1999-01-01

    We study inverse bremsstrahlung in the ultrahigh intensity relativistic regime. The fully relativistic ultrahigh intensity absorption (emission) coefficient is derived for an arbitrary scattering potential and small-angle scattering. We find that in the Coulomb field case this absorption (emission) coefficient can be calculated as a function of the quiver energy, drift momentum, and impact parameter in two complementary regimes: (i) for remote collisions when the impact parameter is larger than the amplitude of the quiver motion, and (ii) for instantaneous collisions when the scattering time is shorter than the period of the wave. Both circular and linear polarizations are considered, and this study reveals that in this relativistic regime inverse bremsstrahlung absorption can be viewed as a harmonic Compton resonance heating of the laser-driven electron by the virtual photon of the ion Coulomb field. The relativistic modification of Marcuse's effect [Bell Syst. Tech. J. 41, 1557 (1962)] are also discussed, and relations with previous nonrelativistic results are elucidated.

  5. Inverse Bremsstrahlung in Shocked Astrophysical Plasmas

    NASA Technical Reports Server (NTRS)

    Baring, Matthew G.; Jones, Frank C.; Ellison, Donald C.

    2000-01-01

    There has recently been interest in the role of inverse bremsstrahlung, the emission of photons by fast suprathermal ions in collisions with ambient electrons possessing relatively low velocities, in tenuous plasmas in various astrophysical contexts. This follows a long hiatus in the application of suprathermal ion bremsstrahlung to astrophysical models since the early 1970s. The potential importance of inverse bremsstrahlung relative to normal bremsstrahlung, i.e. where ions are at rest, hinges upon the underlying velocity distributions of the interacting species. In this paper, we identify the conditions under which the inverse bremsstrahlung emissivity is significant relative to that for normal bremsstrahlung in shocked astrophysical plasmas. We determine that, since both observational and theoretical evidence favors electron temperatures almost comparable to, and certainly not very deficient relative to proton temperatures in shocked plasmas, these environments generally render inverse bremsstrahlung at best a minor contributor to the overall emission. Hence inverse bremsstrahlung can be safely neglected in most models invoking shock acceleration in discrete sources such as supernova remnants. However, on scales approximately > 100 pc distant from these sources, Coulomb collisional losses can deplete the cosmic ray electrons, rendering inverse bremsstrahlung, and perhaps bremsstrahlung from knock-on electrons, possibly detectable.

  6. Attenuation of external Bremsstrahlung in metallic absorbers

    SciTech Connect

    Dhaliwal, A.S.; Powar, M.S.; Singh, M. )

    1990-12-01

    In this paper attenuation of bremsstrahlung from {sup 147}Pm and {sup 170}Tm beta emitters has been studied in aluminum, copper, tin, and lead metallic absorbers. Bremsstrahlung spectra and mass attenuation coefficients for monoenergetic gamma rays are used to calculate theoretical attenuation curves. Magnetic deflection and beta stopping techniques are used to measure the integral bremsstrahlung intensities above 30 keV in different target thicknesses. Comparison of measured and calculated attenuation curves shows a good agreement for various absorbers, thus providing a test of this technique, which may be useful in understanding bremsstrahlung intensity buildup and in the design of optimum shielding for bremsstrahlung sources. It is found that the absorption of bremsstrahlung in metallic absorbers does not obey an exponential law and that absorbers act as energy filters.

  7. Bremsstrahlung in {alpha} Decay Reexamined

    SciTech Connect

    Boie, H.; Scheit, H.; Jentschura, U. D.; Koeck, F.; Lauer, M.; Schwalm, D.; Milstein, A. I.; Terekhov, I. S.

    2007-07-13

    A high-statistics measurement of bremsstrahlung emitted in the {alpha} decay of {sup 210}Po has been performed, which allows us to follow the photon spectra up to energies of {approx}500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the {alpha} particle and the emitted photon.

  8. Bremsstrahlung in alpha decay reexamined.

    PubMed

    Boie, H; Scheit, H; Jentschura, U D; Köck, F; Lauer, M; Milstein, A I; Terekhov, I S; Schwalm, D

    2007-07-13

    A high-statistics measurement of bremsstrahlung emitted in the alpha decay of (210)Po has been performed, which allows us to follow the photon spectra up to energies of approximately 500 keV. The measured differential emission probability is in good agreement with our theoretical results obtained within the quasiclassical approximation as well as with the exact quantum mechanical calculation. It is shown that, due to the small effective electric dipole charge of the radiating system, a significant interference between the electric dipole and quadrupole contributions occurs, which is altering substantially the angular correlation between the alpha particle and the emitted photon.

  9. An experimental test of the LPM effect: Bremsstrahlung suppression at high energies

    SciTech Connect

    Klein, S.; Cavalli-Sforza, M.; Kelley, L.; Anthony, P.; Dietrich, F.; Vanbibber, K.; Becker-Szendy, R.; Gearhart, R.; Niemi, G.; Perl, M.; Rochester, L.; Bosted, P.; Cowan, R.

    1992-11-01

    We are preparing an experiment at SLAC to test the LPM (Landau-Pomeranchuk-Migda) effect. In bremsstrahlung from high energy electrons, the longitudinal momentum transferred from the nucleus is very small. Then, by the uncertainty principle, the interaction must occur over a distance much larger than the atomic scale. In the LPM effect, multiple scattering changes the electron trajectory within the interaction distance, and so suppresses the bremsstrahlung. This effect, predicted in the 1950`s, has never been quantitatively studied. For dense, high Z, targets in a 25 GeV electron beam, suppression is significant for photons below a few hundred MeV. By comparing bremsstrahlung from targets of different (Pb, U, W and C), it is possible to measure the suppression accurately. We will also study the longitudinal density effect, where very low energy photon emission is suppressed due to the dielectric effect of the medium.

  10. An experimental test of the LPM effect: Bremsstrahlung suppression at high energies

    SciTech Connect

    Klein, S.; Cavalli-Sforza, M.; Kelley, L. . Inst. for Particle Physics); Anthony, P.; Dietrich, F.; Vanbibber, K. ); Becker-Szendy, R.; Gearhart, R.; Niemi, G.; Perl, M.; Rochester, L. ); Bosted, P. (American Univ., Washington, DC (United

    1992-11-01

    We are preparing an experiment at SLAC to test the LPM (Landau-Pomeranchuk-Migda) effect. In bremsstrahlung from high energy electrons, the longitudinal momentum transferred from the nucleus is very small. Then, by the uncertainty principle, the interaction must occur over a distance much larger than the atomic scale. In the LPM effect, multiple scattering changes the electron trajectory within the interaction distance, and so suppresses the bremsstrahlung. This effect, predicted in the 1950's, has never been quantitatively studied. For dense, high Z, targets in a 25 GeV electron beam, suppression is significant for photons below a few hundred MeV. By comparing bremsstrahlung from targets of different (Pb, U, W and C), it is possible to measure the suppression accurately. We will also study the longitudinal density effect, where very low energy photon emission is suppressed due to the dielectric effect of the medium.

  11. The generation of gravitational waves. IV - Bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Kovacs, S. J., Jr.; Thorne, K. S.

    1978-01-01

    Previously derived waveforms for gravitational bremsstrahlung are discussed along with their spectra and their limiting structure at high and low relative velocities. Waveforms and spectra are presented for a low-velocity bremsstrahlung encounter, and waveforms are given for encounters of arbitrary relative velocity. Limiting forms for the gravitational-wave amplitudes in the 'forward', 'intermediate', and 'backward' regions are derived in the high-velocity limit. The energy spectra seen by observers in the three regions are computed for arbitrary and high velocities. Simpler methods for analyzing special cases of the bremsstrahlung problem are examined, and the results of those methods are compared with the present results. Those methods include the quadrupole-moment and post-Newtonian formalisms, linear perturbations of the Schwarzschild metric, the method of colliding plane waves, the method of virtual quanta, and the zero-frequency limit. Classical gravitational bremsstrahlung is then compared with classical electromagnetic bremsstrahlung.

  12. Thermal bremsstrahlung from high-temperature plasmas

    SciTech Connect

    Gould, R.J.

    1980-06-15

    Analytic expressions are derived for the total bremsstrahlung energy-loss rate per unit volume and the spectral emission rate per unit volume and the spectral emission rate of a very hot (approx.10/sup 7/-10/sup 9/ K) plasma. At these temperatures the principal contribution to emission can be computed from the nonrelativistic limit of electron-ion bremsstrahlung in the Born approximation. Modifications to this rate are evaluated from (1) relativistic corrections to the thermal-electron velocity distribution function, (2) relativistic and spin corrections to the nonrelativistic electron-ion bremsstrahlung cross section, (3) electron-electron bremsstrahlung, and (4) first-order Born approximation corrections to electron-ion bremsstrahlung. Modifications (1), (2), and (3) are of relative order kT/mc/sup 2/, and modification (4) is of relative order (Ry/kT)/sup 1/2/; at 10/sup 8/ K, each is of order 10%.

  13. Measurements of bremsstrahlung produced by energetic electron bombardment of thick targets - II

    SciTech Connect

    Bauer, R.W.; Becker, J.A.; Farley, W.E.

    1987-07-01

    Samples of C (carbon), Al (aluminum), Fe (iron), and U (uranium), 1 inch thick, together with composite samples C/Al, and C/Al,U, have been bombrded by electrons of energy E/sub e/ = 40, 60, and 84 MeV. A status report of measurements of the thick-target bremsstrahlung for angles of 83.5, 96 and 107 degrees is presented.

  14. Relativistic Non-Thermal Bremsstrahlung Radiation

    NASA Astrophysics Data System (ADS)

    Zeković, Vladimir; Arbutina, Bojan; Dobardžić, Aleksandra; Pavlović, Marko Z.

    2013-11-01

    By applying a method of virtual quanta we derive formulae for relativistic non-thermal bremsstrahlung radiation from relativistic electrons as well as from protons and heavier particles with power-law momentum distribution N(p)dp = k p-qdp. We show that emission which originates from an electron scattering on an ion, represents the most significant component of relativistic non-thermal bremsstrahlung. Radiation from an ion scattering on electron, known as inverse bremsstrahlung, is shown to be negligible in overall non-thermal bremsstrahlung emission. These results arise from theory refinement, where we introduce the dependence of relativistic kinetic energy of an incident particle, upon the energy of scattered photon. In part, it is also a consequence of a different mass of particles and relativistic effects.

  15. Energy Calibration of the JLab Bremsstrahlung Tagging System

    SciTech Connect

    Stepan Stepanyan; S. Boyarinov; H. Egiyan; D. Dale; L. Guo; M. Gabrielyan; L. Gan; Ashot Gasparian; Bernhard Mecking; A. Teymurazyan; I. Nakagawa; Oleksandr Glamazdin; Michael Wood

    2007-03-01

    In this report, we present the energy calibration of the Hall B bremsstrahlung tagging system at the Thomas Jefferson National Accelerator Facility. The calibration was performed using a magnetic pair spectrometer. The tagged photon energy spectrum was measured in coincidence with e{sup +}e{sup -} pairs as a function of the pair spectrometer magnetic field. Taking advantage of the internal linearity of the pair spectrometer, the energy of the tagging system was calibrated at the level of {+-} 0.1% E{sub {gamma}}. The absolute energy scale was determined using the e{sup +}e{sup -} rate measurements close to the end-point of the photon spectrum. The energy variations across the full tagging range were found to be <3 MeV.

  16. Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes

    NASA Technical Reports Server (NTRS)

    Krause, L. Habsh; Gilchrist, B. E.; Nishikawa, Ken-Ichi

    2013-01-01

    Relativisitic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and space reuseable launch vehicles (sRLVs). The monoenergetic beam is modeled in cylindrical symetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremsstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

  17. Low-energy electron-atom bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Gould, R. J.

    1986-01-01

    This paper extends recent work providing an elementary calculation of bremsstrahlung and opacity associated with the scattering of low-energy electrons by neutral atoms and molecules. The method applies when the scattering potential is 'hard' or when the collision time is short, applying the classical soft-photon emission probability formula for arbitrary bremsstrahlung photon energy. However, now, in addition to correcting the probability factor for finite bremsstrahlung photon energy, another factor corrects for the reduced phase space available to the outgoing electron. The bremsstrahlung cross section and opacity are then computed directly from the elastic scattering cross section, determined experimentally or calculated; a small (approximately 10 percent) correction is computed from the anisotropic term in the elastic scattering cross section. The opacity is evaluated for electron scattering by H, He, and H2 using experimentally determined values for the elastic scattering cross section, and is compared with more elaborate calculations. The agreement is good (within 10 percent), indicating an accuracy for the general method comparable to variations among the results of different elaborate theoretical computations. The agreement seems to validate the basic approximation of short collision time even at large bremsstrahlung photon energy for electron energies and temperatures up to a few eV.

  18. Bremsstrahlung emission of high energy accompanying spontaneous fission of {sup 252}Cf

    SciTech Connect

    Maydanyuk, S. P.; Olkhovsky, V. S.; Mandaglio, G.; Manganaro, M.; Fazio, G.; Giardina, G.

    2010-07-15

    The study of the bremsstrahlung photon emission accompanying fragments produced in the spontaneous fission of heavy nuclei by a fully quantum approach is presented for the first time. This kind of problem requires the knowledge of wave functions of the fissioning system leading to a wide distribution of couples of fragments that are the products of fission. With the aim of obtaining these wave functions, the interaction potential between the emitted fragment and residual nucleus is calculated by a standard approach. A new procedure was performed that allows an increase in the accuracy of calculations of radial integrals in the far asymptotic region and the achievement of the convenient convergence in calculations of the spectra. The total probability of the emitted photons in the spontaneous fission of {sup 252}Cf was calculated in such a way. We obtained good agreement between theory and experimental data up to 38 MeV for the bremsstrahlung spectrum of photons while the calculation of the total probability of photon emission accompanying fragments was performed up to an energy of 60 MeV. The analysis of contributions in the bremsstrahlung spectrum accompanying the emission of light, medium, and heavy fragments in the fission of {sup 252}Cf is presented.

  19. Electron accelerator-based production of molybdenum-99: Bremsstrahlung and photoneutron generation from molybdenum vs. tungsten

    NASA Astrophysics Data System (ADS)

    Tsechanski, A.; Bielajew, A. F.; Archambault, J. P.; Mainegra-Hing, E.

    2016-01-01

    A new "one-stage" approach for production of 99Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of 99Mo via the photoneutron reaction 100Mo(γ,n)99Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r0) W target, for target thickness z > 1.84r0, where r0 is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r0) for target thickness case: z ⩾ 2.0r0. It is shown for the one-stage approach with thicknesses of (1.84-2.0)r0, that the 99Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r0) in the traditional two-stage approach (W converter and separate 99Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the 99Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity for the one-stage approach of three enriched 100Mo-targets of a 2 cm diameter and

  20. Determination of the temperature of bremsstrahlung photon generated by ultraintense laser using various thickness attenuators

    SciTech Connect

    Hasegawa, Shuichi; Takashima, Ryuta; Todoriki, Masaru; Kikkawa, Satoshi; Soda, Keita; Takano, Kei; Oishi, Yuji; Nayuki, Takuya; Fujii, Takashi; Nemoto, Koshichi

    2011-03-15

    We evaluate the simplified method using the Lambert-Beer law to measure the temperature of bremsstrahlung photon generated by an ultraintense laser. Analytical values are compared to the results of the Monte Carlo calculation of GEANT4 and they agreed very well on the condition of the appropriate distance between the attenuator and the detector. We performed the experiment to measure the temperature of bremsstrahlung x-ray emitted from a metal target irradiated by a Ti:sapphire laser with 76 mJ, 72 fs, 2.2 x 10{sup 18} W/cm{sup 2}. For a Cu target of 30 {mu}m thick, the photon temperature was reasonably determined to be 0.18 MeV, which is in good agreement with previous studies.

  1. Relativistic theory for the elementary process of bremsstrahlung induced by heavy spin-zero nuclei

    NASA Astrophysics Data System (ADS)

    Jakubassa-Amundsen, D. H.

    2016-05-01

    Doubly and triply differential cross sections for the bremsstrahlung emission by high-energy spin-polarized electrons in the field of heavy bare nuclei are calculated within a fully relativistic partial-wave approach at collision energies between 1 and 30 MeV. Investigating 208Pb as a test case, it is shown that if the photons are emitted at backward angles, nuclear size effects may play an important role even below 10 MeV. Comparison is made with experimental data on the circular polarization correlations between incoming electron and emitted photon at a collision energy of 3.5 MeV. It is demonstrated that, independent of energy, the plane-wave Born approximation severely underestimates the cross section for heavy targets. Moreover, it gives at most a qualitative prescription of the polarization correlations, except possibly in the forward hemisphere.

  2. Bremsstrahlung from relativistic bare heavy ions: Nuclear and electronic contributions in amorphous and crystalline materials

    NASA Astrophysics Data System (ADS)

    Jensen, Tue V.; Sørensen, Allan H.

    2013-02-01

    A charged particle emits bremsstrahlung while traversing matter. We calculate the radiation cross section for bare heavy ions penetrating amorphous materials and single crystals at highly relativistic energies. The main component originates in scattering of the virtual photons of screened target nuclei on the projectile. It appears at, approximately, 2γ times the energy of the giant dipole resonance of the projectile, approximately 25γ MeV for a lead nucleus (γ≡E/Mc2, where E and M denote the projectile energy and mass). The emission pertains to relatively close impacts, with impact parameters ranging to, at maximum, the screening radius of the target atoms. As a result, the main bremsstrahlung component shows channeling dips, that is, dips in yield upon variation of the incidence angle to major crystallographic directions of a single crystal. The minimum yield increases with γ but saturates at a very low value. Incoherent interaction with single target electrons gives rise to two additional bremsstrahlung components, a modest component due to scattering of virtual photons of the electrons on the projectile and a strong low-energy component due to scattering of the virtual photons of the projectile on the electrons. The difference in radiation levels can be traced to the mass of the scatterer. Since target electrons are more widely distributed than nuclei in a crystal channel the variation of the electron component of the bremsstrahlung with incidence angle to a major crystallographic direction is less abrupt than the variation of the nuclear component. In consequence, the shape of the total bremsstrahlung spectrum changes when the crystal is tilted and the individual components may be singled out. Pair creation is also sensitive to the orientation of a crystalline material, resulting in a pronounced directional dependence of the energy loss of bare heavy ions at extreme relativistic energies.

  3. High-power, photofission-inducing bremsstrahlung source for intense pulsed active detection of fissile material

    NASA Astrophysics Data System (ADS)

    Zier, J. C.; Mosher, D.; Allen, R. J.; Commisso, R. J.; Cooperstein, G.; Hinshelwood, D. D.; Jackson, S. L.; Murphy, D. P.; Ottinger, P. F.; Richardson, A. S.; Schumer, J. W.; Swanekamp, S. B.; Weber, B. V.

    2014-06-01

    Intense pulsed active detection (IPAD) is a promising technique for detecting fissile material to prevent the proliferation of special nuclear materials. With IPAD, fissions are induced in a brief, intense radiation burst and the resulting gamma ray or neutron signals are acquired during a short period of elevated signal-to-noise ratio. The 8 MV, 200 kA Mercury pulsed-power generator at the Naval Research Laboratory coupled to a high-power vacuum diode produces an intense 30 ns bremsstrahlung beam to study this approach. The work presented here reports on Mercury experiments designed to maximize the photofission yield in a depleted-uranium (DU) object in the bremsstrahlung far field by varying the anode-cathode (AK) diode gap spacing and by adding an inner-diameter-reducing insert in the outer conductor wall. An extensive suite of diagnostics was fielded to measure the bremsstrahlung beam and DU fission yield as functions of diode geometry. Delayed fission neutrons from the DU proved to be a valuable diagnostic for measuring bremsstrahlung photons above 5 MeV. The measurements are in broad agreement with particle-in-cell and Monte Carlo simulations of electron dynamics and radiation transport. These show that with increasing AK gap, electron losses to the insert and outer conductor wall increase and that the electron angles impacting the bremsstrahlung converter approach normal incidence. The diode conditions for maximum fission yield occur when the gap is large enough to produce electron angles close to normal, yet small enough to limit electron losses.

  4. Bremsstrahlung gamma rays from light dark matter

    SciTech Connect

    Cirelli, Marco; Zaharijas, Gabrijela E-mail: serpico@lapth.cnrs.fr

    2013-11-01

    We discuss the often-neglected role of bremsstrahlung processes on the interstellar gas in computing indirect signatures of Dark Matter (DM) annihilation in the Galaxy, particularly for light DM candidates in the phenomenologically interesting O(10) GeV mass range. Especially from directions close to the Galactic Plane, the γ-ray spectrum is altered via two effects: directly, by the photons emitted in the bremsstrahlung process by energetic electrons which are among the DM annihilation byproducts; indirectly, by the modification of the same electron spectrum, due to the additional energy loss process in the diffusion-loss equation (e.g. the resulting inverse Compton emission is altered). We quantify the importance of the bremsstrahlung emission in the GeV energy range, showing that it is sometimes the dominant component of the γ-ray spectrum. We also find that, in regions in which bremsstrahlung dominates energy losses, the related γ-ray emission is only moderately sensitive to possible large variations in the gas density. Still, we stress that, for computing precise spectra in the (sub-)GeV range, it is important to obtain a reliable description of the Galaxy gas distribution as well as to compute self-consistently the γ-ray emission and the solution to the diffusion-loss equation. For example, these are crucial issues to quantify and interpret meaningfully γ-ray map 'residuals' in the inner Galaxy.

  5. Characterization of intense laser-produced fast electrons using hard x-rays via bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Sawada, H.; Sentoku, Y.; Bass, A.; Griffin, B.; Pandit, R.; Beg, F.; Chen, H.; McLean, H.; Link, A. J.; Patel, P. K.; Ping, Y.

    2015-11-01

    Energy distribution of high-power, short-pulse laser produced fast electrons was experimentally and numerically studied using high-energy bremsstrahlung x-rays. The hard x-ray photons and escaping electrons from various metal foils, irradiated by the 50 TW Leopard laser at Nevada Terawatt Facility, were recorded with a differential filter stack spectrometer that is sensitive to photons produced by mainly 0.5-2 MeV electrons and an electron spectrometer measuring >2 MeV electrons. The experimental bremsstrahlung and the slope of the measured escaped electrons were compared with an analytic calculation using an input electron spectrum estimated with the ponderomotive scaling. The result shows that the electron spectrum entering a Cu foil could be continuous single slope with the slope temperature of ˜1.5 MeV in the detector range. The experiment and analytic calculation were then compared with a 2D particle-in-cell code, PICLS, including a newly developed radiation transport module. The simulation shows that a two-temperature electron distribution is generated at the laser interaction region, but only the hot component of the fast electrons flow into the target during the interaction because the low energy electron component is trapped by self-generated magnetic field in the preformed plasma. A significant amount of the photons less than 100 keV observed in the experiment could be attributed to the low energy electrons entering the foil a few picoseconds later after the gating field disappears.

  6. Bremsstrahlung: an experimentalist's personal perspective on the postmodern era

    NASA Astrophysics Data System (ADS)

    Quarles, C. A.

    2000-08-01

    In this brief review I will discuss the recent experimental work on the doubly differential cross section, i.e. the photon energy and angular distribution, for electron bremsstrahlung from thin solid film and gas targets. Since the beginning of the modern era in the study of bremsstrahlung with the publication of the 1971 paper by Tseng and Pratt, Professor Pratt has been the dominant influence in bremsstrahlung research. Most, if not all, experimental research during the modern era has been motivated by the interest in comparing data with the theory of Pratt and his coworkers. As bremsstrahlung research has moved into its postmodern era, new experiments with increasing precision are concentrating on determining under what conditions ordinary bremsstrahlung theory needs to be supplemented by a contribution from polarization bremsstrahlung. Efforts to improve the comparison of thin-target experiment with theory have also led to new experimental and modeling work on bremsstrahlung from thick solid targets. Thick-target bremsstrahlung is interesting in its own right, but we also want to understand it better since it is the ever-present background in the thin-target experiments and the limiting factor in the effort to distinguish the polarization contribution to the total bremsstrahlung spectrum. Professor Pratt ushered in the modern era in bremsstrahlung research and has recently guided the transition into the postmodern era. It can be expected that he will continue to have a formative influence on the developments of bremsstrahlung research into the foreseeable future.

  7. Modeling Relativistic Electron Precipitation Bremsstrahlung X-Ray Intensities at 10-100 km Manned Vehicle Altitudes

    NASA Astrophysics Data System (ADS)

    Habash Krause, L.; Gilchrist, B. E.; Nishikawa, K.; Williams, A.

    2013-12-01

    Relativistic electron precipitation (REP) events occur when beams or bunches of relativistic electrons of magnetospheric origin enter the Earth's atmosphere, typically at auroral latitudes. REP events are associated with a variety of space weather effects, including production of transitional and bremsstrahlung radiation, catalytic depletion of stratospheric ozone, and scintillation of transionospheric radio waves. This study examines the intensities of x-rays produced at airliner, manned balloon, and suborbital Reusable Launch Vehicle (sRLV) altitudes. The monoenergetic beam is modeled in cylindrical symmetry using the paraxial ray equation. Bremsstrahlung photon production is calculated using the traditional Sauter-Elwert cross-section, providing x-ray emission spectra differential in energy and angle. Attenuation is computed for a plane-stratified standard atmosphere, and the loss processes include photoionization, Rayleigh and Compton scattering, electron-positron pair production, and photonuclear interaction. Peak altitudes of electron energy deposition and bremsstrahlung x-ray production were calculated for beams of energies from 1 MeV through 100 MeV. The altitude peak of bremsstrahlung deposition was consistently and significantly lower that that of the electron deposition due to the longer mean free paths of x-rays compared to electrons within the atmosphere. For example, for a nadir-directed monoenergetic 5 MeV beam, the peak deposition altitude was calculated to be 42 km, but the resulting bremmstrahlung deposition peaked at 25 km. This has implications for crew and passenger safety, especially with the growth of the space tourism industry that relies on sRLVs with a nominal apogee of 100 km. A survey of results covering the 1-100 MeV spectrum for the three altitude ranges of interest will be presented.

  8. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media.

    PubMed

    Kumar, Sudhir; Nahum, Alan E

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of 'secondary bremsstrahlung' along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV 'clinical' radiotherapy qualities. Concerning depth-dependence, the 'area under the kerma, K, curve' exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the 'double counting' of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma 'liberated' in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this 'violation' amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a 'clinical' 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm−2 for both very high and very low charged-particle transport cut-offs reveals the considerable

  9. Noncoplanarity effects in proton-proton bremsstrahlung

    SciTech Connect

    Li, Y.; Liou, M.K.; Timmermans, R.; Gibson, B.F.

    1998-10-01

    Noncoplanarity in proton-proton bremsstrahlung is investigated. Significant effects are observed for certain photon polar angles, {psi}{sub {gamma}}. Such noncoplanarity effects, not of dynamical origin, are possibly responsible for past disagreements between theory and experiment. The Harvard noncoplanar coordinate system, which avoids kinematic singularities in the cross section, is used in our calculations and is recommended for use in the analysis of experimental data. Alternative methods of presenting cross sections are discussed. {copyright} {ital 1998} {ital The American Physical Society}

  10. Bremsstrahlung Temperature Scaling in Ultra-Intense Laser-Plasma Interactions

    NASA Astrophysics Data System (ADS)

    Zulick, C.; Hou, B.; Nees, J.; Thomas, A. G. R.; Krushelnick, K.

    2011-10-01

    The absorption of laser energy during ultra-intense (I > 1018 W/cm2) laser-plasma interactions results in the production of a hot electron current, which can subsequently generate energetic protons, ions, and photons. The energetic photons are of particular interest in isomer excitation, positron production, and homeland security applications. Experiments were performed on the high repetition rate (500 Hz) Lambda Cubed laser (I ~ 5 .1018 , duration 30 fs) allowing high resolution (λ/ Δλ = 300) spectroscopy of X-ray and γ-ray bremsstrahlung photons in the 20 keV to 3 MeV energy range. The effective bremsstrahlung temperature was measured over a range of laser energies, target materials, and detection angles. Additionally, simulations (MCNPX and GEANT4) were used to correlate experimental bremsstrahlung temperatures with hot electron temperatures, which were compared to existing electron temperature scaling laws. This work was supported by the National Science Foundation (NSF) through the FOCUS Physics Frontier Center PHY-0114336, and by the Department of Homeland Security and NSF through grant EECS-0833499.

  11. Bremsstrahlung doses from natural uranium ingots.

    PubMed

    Anderson, Jeri L; Hertel, Nolan E

    2005-01-01

    In the past, some privately owned commercial facilities in the United States were involved in producing or processing radioactive materials used in the production of atomic weapons. Seven different geometrical objects, representative of the configurations of natural uranium metal potentially encountered by workers at these facilities, are modelled to determine gamma ray and bremsstrahlung dose rates. The dose rates are calculated using the MCNP5 code and also by using the MICROSHIELD point-kernel code. Both gamma ray and bremsstrahlung dose rates are calculated and combined to obtain a total dose rate. The two methods were found to be in good agreement despite differences in modelling assumptions and method differences. Computed total dose rates on the surface of these objects ranged from approximately 51-84 microSv h(-1) and 17-95 microSv h(-1) using the MCNP5 and the MICROSHIELD modeling, respectively. The partitioning of the computed dose rates between gamma rays and bremsstrahlung were the same order of magnitude for each object.

  12. The effect of the {Delta} excitation on proton-proton bremsstrahlung

    SciTech Connect

    Lee, T.S.H.; Jong, F. de; Nakayama, K.

    1995-08-01

    The proton-proton bremsstrahlung is investigated with a coupled-channel model with {pi} and {Delta} degrees of freedom. The model is consistent with the NN scattering up to 1 GeV and the {gamma}N{Delta} vertex determined in the study of pion photoproduction on the nucleon. We find that the {Delta} excitation can significantly improve the agreement with the pp {yields} pp{gamma} data at E{sub L} = 280 MeV. The N{Delta} rescattering plays an important role in determining the angular distribution and analyzing powers. Predictions at E{sub L} = 550 and 800 MeV were made for the forthcoming experimental tests at COSY of Juelich. A paper describing our results was submitted for publication.

  13. Meson exchange currents in neutron-proton bremsstrahlung

    SciTech Connect

    Li Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F.; Timmermans, R. G. E.

    2008-04-15

    Background: The meson exchange current (MEC) contribution is important in the neutron-proton bremsstrahlung process (np{gamma}) when the two nucleon-scattering angles are small. However, our understanding of such effects is limited, and the reason why meson exchange current effects dominate the np{gamma} cross section has not been thoroughly investigated. Purpose: The primary focus of this investigation is to understand the origin of the MEC contribution, to identify the leading MEC amplitudes, and to comprehend why these MEC amplitudes dominate the np{gamma} cross sections. Method: We used a new method that combines the one-boson-exchange (OBE) approach with the soft-photon approach to define 10 different np{gamma} amplitudes. These amplitudes are used to calculate np{gamma} cross sections at 225 MeV for nucleon laboratory scattering angles lying between 12 deg. and 43 deg. The results of these calculations are then compared to investigate the meson exchange current effect in np{gamma}. Results: (i) The OBE amplitude M{sub np{gamma}}{sub ,{mu}}{sup PS} and the two-u-two-t special (TuTts) soft-photon amplitude M{sub np{gamma}}{sub ,{mu}}{sup TuTts} predict quantitatively similar np{gamma} cross sections. (ii) The MEC effect is found to be significant when the two nucleon-scattering angles are far from the elastic limit (45 deg.), but the effect is insignificant when the nucleon angles approach the elastic limit. (iii) The origin of the MEC effect and the leading MEC amplitudes have been identified in this investigation. Furthermore, the reason is now clear why the leading MEC amplitudes dominate the np{gamma} cross section when the nucleon-scattering angles are small. (iv) The contribution from the anomalous magnetic moments of the proton and the neutron is confirmed to be negligibly small. (v) In general, the theoretical cross sections using the amplitude M{sub np{gamma}}{sub ,{mu}}{sup PS}, or the amplitude M{sub np{gamma}}{sub ,{mu}}{sup TuTts}, are consistent

  14. The small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield of cosmic ray shower particles

    NASA Astrophysics Data System (ADS)

    Al Samarai, Imen; Deligny, Olivier; Rosado, Jaime

    2016-10-01

    A small contribution of molecular Bremsstrahlung radiation to the air-fluorescence yield in the UV range is estimated based on an approach previously developed in the framework of the radio-detection of showers in the gigahertz frequency range. First, this approach is shown to provide an estimate of the main contribution of the fluorescence yield due to the de-excitation of the C 3Πu electronic level of nitrogen molecules to the B 3Πg one amounting to Y[ 337 ] =(6.05 ± 1.50) MeV-1 at 800 hPa pressure and 293 K temperature conditions, which compares well to previous dedicated works and to experimental results. Then, under the same pressure and temperature conditions, the fluorescence yield induced by molecular Bremsstrahlung radiation is found to be Y[330-400]MBR = 0.10 MeV-1 in the wavelength range of interest for the air-fluorescence detectors used to detect extensive air showers induced in the atmosphere by ultra-high energy cosmic rays. This means that out of ≃175 photons with wavelength between 330 and 400 nm detected by fluorescence detectors, one of them has been produced by molecular Bremsstrahlung radiation. Although small, this contribution is not negligible in regards to the total budget of systematic uncertainties when considering the absolute energy scale of fluorescence detectors.

  15. Secondary bremsstrahlung and the energy-conservation aspects of kerma in photon-irradiated media

    NASA Astrophysics Data System (ADS)

    Kumar, Sudhir; Nahum, Alan E.

    2016-02-01

    Kerma, collision kerma and absorbed dose in media irradiated by megavoltage photons are analysed with respect to energy conservation. The user-code DOSRZnrc was employed to compute absorbed dose D, kerma K and a special form of kerma, K ncpt, obtained by setting the charged-particle transport energy cut-off very high, thereby preventing the generation of ‘secondary bremsstrahlung’ along the charged-particle paths. The user-code FLURZnrc was employed to compute photon fluence, differential in energy, from which collision kerma, K col and K were derived. The ratios K/D, K ncpt/D and K col/D have thereby been determined over a very large volumes of water, aluminium and copper irradiated by broad, parallel beams of 0.1 to 25 MeV monoenergetic photons, and 6, 10 and 15 MV ‘clinical’ radiotherapy qualities. Concerning depth-dependence, the ‘area under the kerma, K, curve’ exceeded that under the dose curve, demonstrating that kerma does not conserve energy when computed over a large volume. This is due to the ‘double counting’ of the energy of the secondary bremsstrahlung photons, this energy being (implicitly) included in the kerma ‘liberated’ in the irradiated medium, at the same time as this secondary bremsstrahlung is included in the photon fluence which gives rise to kerma elsewhere in the medium. For 25 MeV photons this ‘violation’ amounts to 8.6%, 14.2% and 25.5% in large volumes of water, aluminium and copper respectively but only 0.6% for a ‘clinical’ 6 MV beam in water. By contrast, K col/D and K ncpt/D, also computed over very large phantoms of the same three media, for the same beam qualities, are equal to unity within (very low) statistical uncertainties, demonstrating that collision kerma and the special type of kerma, K ncpt, do conserve energy over a large volume. A comparison of photon fluence spectra for the 25 MeV beam at a depth of  ≈51 g cm-2 for both very high and very low charged-particle transport cut

  16. Bremsstrahlung spectra from atoms and ions at low relativistic energies

    NASA Astrophysics Data System (ADS)

    Avdonina, N. B.; Pratt, R. H.

    1999-09-01

    Analytic expressions for bremsstrahlung spectra from neutral atoms and ions, including the polarizational bremsstrahlung contribution in a stripped atom approximation, are developed for electron scattering at energies of 10-2000 keV. A modified Elwert factor and a simple higher Born correction are used for the Coulomb spectrum, with ordinary bremsstrahlung screening effects in ions and atoms adequately characterized in the non-relativistic Born approximation. In parallel with the development of this analytic description, new numerical results are obtained for ordinary bremsstrahlung from ions and from bare nuclei, appreciably extending the available data set which can be used to study dependences on element, ionicity, energy and the fraction of incident energy radiated. The accuracy of predictions with the analytic expressions is then determined by comparison with the full numerical relativistic partial-wave results for ordinary bremsstrahlung and with non-relativistic numerical results in the Born approximation or in partial waves for the polarizational amplitude.

  17. Bremsstrahlung dosimetric parameters of beta-emitting therapeutic radionuclides

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.

    2016-03-01

    Dosimetric parameters such as efficiency of bremsstrahlung, probability of energy loss of beta during bremsstrahlung production, intensity and dose rate of high, medium and low-energy beta-emitting therapeutic radionuclides in different tissues of human organs are computed. These parameters are lower in adipose tissue than all other studied tissues. The efficiency, intensity and dose rate of bremsstrahlung increases with maximum energy of the beta nuclide (Emax) and modified atomic number (Zmod) of the target tissue. The estimated bremsstrahlung efficiency, intensity and dose rate are useful in the calculations of photon track-length distributions. These parameters are useful to determine the quality and quantity of the bremsstrahlung radiation (known as the source term). Precise estimation of this source term is very important in planning for radiotherapy and diagnosis.

  18. Bremsstrahlung target optimization for reflex triodes

    SciTech Connect

    Swanekamp, S. B.; Weber, B. V.; Stephanakis, S. J.; Mosher, D.; Commisso, R. J.

    2008-08-15

    The anode (tantalum) foil thickness in a reflex triode was varied from 2.5 to 250 {mu}m to maximize the dose from bremsstrahlung produced by a 1 MV, 1 MA, 100 ns electron beam. Experiments and computer simulations show that the dose is maximized for a foil thickness of about 25 {mu}m, 1/18th of the electron range computed from the continuous slowing down approximation. For foils thicker than optimum, self-absorption in the foil attenuates 10-100 keV photons, reducing the dose. For foils thinner than optimum, the dose decreases as a result of electron migration to large radius. A simple formula that predicts the optimum thickness as a function of the beam current and voltage is derived that should be applicable to a large range of experimental parameters.

  19. Weibel instability due to inverse bremsstrahlung absorption

    SciTech Connect

    Bendib, A.; Bendib, K.,; Bendib, A.; Bendib, K.; Sid, A.,; Bendib, K.,

    1997-06-01

    A new Weibel source due to the inverse bremsstrahlung absorption is presented. It has been shown that in homogeneous plasmas, this mechanism may drive strong collisionless Weibel modes with growth rates of order of {gamma}{approximately}10{sup 11}s{sup {minus}1} and negligible group velocities. In the laser-produced plasmas, for short laser wavelengths ({lambda}{sub L}{lt}1{mu}m) and high laser fluxes (I{gt}10{sup 14}W/cm{sup 2}), this Weibel source is most efficient as the ones due to the heat flux and the plasma expansion. The useful scaling law of the convective e-foldings, with respect to the laser and the plasma parameters, is also derived. {copyright} {ital 1997} {ital The American Physical Society}

  20. Photofission product yields of 238U and 239Pu with 22-MeV bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Wen, Xianfei; Yang, Haori

    2016-06-01

    In homeland security and nuclear safeguards applications, non-destructive techniques to identify and quantify special nuclear materials are in great demand. Although nuclear materials naturally emit characteristic radiation (e.g. neutrons, γ-rays), their intensity and energy are normally low. Furthermore, such radiation could be intentionally shielded with ease or buried in high-level background. Active interrogation techniques based on photofission have been identified as effective assay approaches to address this issue. In designing such assay systems, nuclear data, like photofission product yields, plays a crucial role. Although fission yields for neutron-induced reactions have been well studied and readily available in various nuclear databases, data on photofission product yields is rather scarce. This poses a great challenge to the application of photofission techniques. In this work, short-lived high-energy delayed γ-rays from photofission of 238U were measured in between linac pulses. In addition, a list-mode system was developed to measure relatively long-lived delayed γ-rays from photofission of 238U and 239Pu after the irradiation. Time and energy information of each γ-ray event were simultaneously recorded by this system. Cumulative photofission product yields were then determined using the measured delayed γ-ray spectra.

  1. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    NASA Astrophysics Data System (ADS)

    Embréus, O.; Stahl, A.; Fülöp, T.

    2016-09-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum‑space structure of the electron distribution, fully accounting for the emission of finite‑energy photons by modeling the bremsstrahlung interactions with a Boltzmann collision operator. We find that electrons accelerated by electric fields can reach significantly higher energies than predicted by the commonly used radiative stopping‑power model. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution by causing pitch‑angle scattering at a rate that increases with energy.

  2. Effect of bremsstrahlung radiation emission on fast electrons in plasmas

    NASA Astrophysics Data System (ADS)

    Embréus, O.; Stahl, A.; Fülöp, T.

    2016-09-01

    Bremsstrahlung radiation emission is an important energy loss mechanism for energetic electrons in plasmas. In this paper we investigate the effect of spontaneous bremsstrahlung emission on the momentum-space structure of the electron distribution, fully accounting for the emission of finite-energy photons by modeling the bremsstrahlung interactions with a Boltzmann collision operator. We find that electrons accelerated by electric fields can reach significantly higher energies than predicted by the commonly used radiative stopping-power model. Furthermore, we show that the emission of soft photons can contribute significantly to the dynamics of electrons with an anisotropic distribution by causing pitch-angle scattering at a rate that increases with energy.

  3. Comparison of Techniques to Reduce Bremsstrahlung Background Radiation from Monoenergetic Photon Beams

    SciTech Connect

    Johnson, M; McNabb, D

    2006-06-29

    An important applied technology is a tunable mono-energetic photon source [1]. These sources are made of relativistic electron accelerators coupled to low-energy lasers, which produce high-energy, mono-energetic-rays. One challenge associated with systems such as this is a continuum of bremsstrahlung background created when an electron beam passes through an aperture of some sort and the electron bunch or its halo impinges on the aperture pictured in figure 1. For instance, in the current T-REX [1] design for the interaction point between the laser- and electron-beam, the electron-beam passes through the center of a mirror used to reflect the laser. There is a potential with this design that bremsstrahlung radiation may be produced at the edges of the mirror openings and contaminate the mono-energetic photon beam. Certain applications [2] may be sensitive to this contamination. To reduce the bremsstrahlung contaminate a collimator (thickness {approx}24in. (calculated from XCOM database [3]) to attenuate by a factor of 10{sup -3} the 112MeV photons expected in the T-REX demonstration [1]) is situated between the aperture and target. To maximize the brightness of the photon-beam, the collimator opening must be no less than the size of the photon-beam spot size expected to be about 1mm. This fixes the collimator opening. a priori the aperture size must be greater than the collimator opening and is a function distance between the aperture and collimator. In this paper we focus on two approaches to estimate the aperture size, given a collimator and a target whose sizes and distances from the aperture are given. In the next section we will discuss these approaches.

  4. Analysis of Fast Electron Energy Distribution by Measuring Hard X-ray Bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Daykin, Tyler; Sawada, Hiroshi; Sentoku, Yasuhiko; Bass, Anthony; Griffin, Brandon; Pandit, Rishi; Beg, Farhat; Chen, Hui; McLean, Harry; Link, Anthony; Patel, Prav; Ping, Yuan

    2015-11-01

    Characterization of intense, short-pulse laser-produced fast electrons is important for fundamental understanding and applications. We carried out an experiment to characterize the fast electron energy distribution by measuring angular-dependent high-energy bremsstrahlung x-rays. A 100 μm thick metal foil (Al, Cu, and Ag) mounted on a plastic backing was irradiated by the 0.35 ps, 15 J Leopard Laser at the Nevada Terawatt Facility. The bremsstrahlung x-rays and the escaping electrons from the target were recorded using differential filter stack spectrometers at 22° and 45° off laser axis and a magnet-based electron spectrometer along the laser axis. The electron spectrum inferred from two different diagnostics had single slope temperature of ~ 1.5 MeV for the Cu foil. The results were compared to an analytic calculation and a 2-D Particle-in-cell code, PICLS. The analysis of the electron energy distribution and angular distribution will be presented. This work was supported by the UNR Office of the Provost and by DOE/OFES under Contract No. DE-SC0008827. This collaborative work was partially supported under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Con.

  5. Analyzing power in pion-proton bremsstrahlung, and the. Delta. sup ++ (1232) magnetic moment

    SciTech Connect

    Bosshard, A.; Amsler, C.; Doebeli, M.; Doser, M.; Schaad, M.; Riedlberger, J.; Truoel, P. ); Bistirlich, J.A.; Crowe, K.M.; Ljungfelt, S.; Meyer, C.A. ); van den Brandt, B.; Konter, J.A.; Mango, S.; Renker, D. ); Loude, J.F.; Perroud, J.P. ); Haddock, R.P. ); Sober, D.I. )

    1991-10-01

    We report on a first measurement of the polarized-target asymmetry of the pion-proton bremsstrahlung cross section ({pi}{sup +}{ital p}{r arrow}{pi}{sup {minus}}{ital p}{gamma}). As in previous cross section measurements the pion energy (298 MeV) and the detector geometry for this experiment was chosen to optimize the sensitivity to the radiation from the magnetic dipole moment of the {Delta}{sup ++}(1232) resonance {mu}{sub {Delta}}. Comparison to a recent isobar model for pion-nucleon bremsstrahlung yields {mu}{sub {Delta}}=(1.62{plus minus}0.18){mu}{sub {ital p}}, where {mu}{sub {ital p}} is the proton magnetic moment. Since the asymmetry depends less than the cross section on the choice of the other input parameters for the model, their uncertainties affect this analysis by less than the experimental error. However the theory fails to represent both the cross section and the asymmetry data at the highest photon energies. Hence further improvements in the calculations are needed before the model dependence of the magnetic moment analysis can be fully assessed. The present result agrees with bag-model corrections to the SU(6) prediction {mu}{sub {Delta}}=2{mu}{sub {ital p}}. As a by-product, the analyzing power for elastic {pi}{sup +}{ital p} scattering at 415 MeV/{ital c} was also measured. This second result is in good agreement with phase shift calculations.

  6. Threshold and spin factors in the yield of bremsstrahlung-induced reactions

    SciTech Connect

    Karamian, S. A.

    2013-12-15

    Relative yields of photon-induced reactions are systematized in a function of the threshold parameter for moderately heavy targets at the bremsstrahlung end-point energy lower than 30 MeV. Regular dependence is established for the group of (γ, n), (γ, p), and (γ, d) reactions, while the yields of (γ, 2n) and (γ,α) reactions deviate from the regularity. Physical conclusions are discussed and possible application of this systematic for data processing is proposed. In particular, the constituent threshold and spin factors in the isomer-to-ground-state ratio could be isolated separately. For spin dependence of the yields, a new regularization parameter is introduced and previously hidden peculiarities are concluded.

  7. Bremsstrahlung versus Monoenergetic Photon Dose and Photonuclear Stimulation Comparisons At Long Standoff Distances

    SciTech Connect

    J. L. Jones; J.W. Sterbentz; W.Y. Yoon

    2009-06-01

    Energetic photon sources with energies greater than 6 MeV continue to be recognized as viable source for various types of inspection applications, especially those related to nuclear and/or explosive material detection. These energetic photons can be produced as a continuum of energies (i.e., bremsstrahlung distribution) or as a set of one or more discrete photon energies (i.e., monoenergetic distribution). This paper will provide a follow-on extension of the photon dose comparison presented at the 9th International Conference on Applications of Nuclear Techniques (June 2008). The latter paper showed the comparative advantages and disadvantages of the photon doses provided by these two energetic interrogation sources and highlighted the higher energy advantage of the bremsstrahlung source, especially at long standoff distances (i.e., distance from source to the inspected object). Specifically, this paper will pursue this higher energy photon inspection advantage (up to 100 MeV) by providing dose and stimulated photonuclear interaction predictions for air and an infinitely dilute interrogated material (used for comparative interaction rate assessments since it excludes material self-shielding) as the interrogation object positioned forward on the inspection beam axis at increasing standoff distances. In addition to the direct energetic photon-induced stimulation, the predictions will identify the importance of any secondary downscattered/attenuated source-term effects arising from the photon transport in the intervening atmosphere. *Supported in part by the Defense Threat Reduction Agency and Department of Energy (DOE) Idaho Operations Office under Contract Number DE-AC07-05ID14517.

  8. Nucleon-nucleon bremsstrahlung: Anomalous magnetic moment effects

    SciTech Connect

    Timmermans, R.G.E.; Penninga, T.D.; Gibson, B.F.; Liou, M.K.

    2006-03-15

    Background: Two soft-photon amplitudes, the two-u-two-t special (TuTts) amplitude and the Low amplitude, are known to produce quantitatively similar np{gamma} cross sections, but they predict quite different pp{gamma} cross sections for those kinematic conditions in which the nucleon scattering angles are small (less than 25 deg.). Purpose: These two amplitudes have been applied to systematically investigate three different nucleon-nucleon bremsstrahlung (NN{gamma}) processes: pp{gamma},np{gamma}, and nn{gamma}. The nn{gamma} process is explored for the first time. The primary focus of this work is to investigate the contribution of the proton and the neutron anomalous magnetic moments to all three NN{gamma} processes for projectile energies above 150 MeV and for laboratory scattering angles ({theta}{sub 1} and {theta}{sub 2}) lying between 8 deg. and 40 deg.. Method: A special soft-photon expansion in which the TuTts amplitude is expanded in terms of the Low amplitude plus additional amplitudes is utilized to explore the relationship between the TuTts and Low amplitudes and the reasons why they agree and disagree. We also used the TuTts amplitude to calculate the NN{gamma} cross section with and without the anomalous magnetic moment contributions to explore the importance of that element of the electromagnetic current. Results: The TuTts amplitude describes well the available pp{gamma} cross-section data. The anomalous magnetic moment contribution is (i) significant in the pp{gamma} process when each scattering angle is less than 25 deg. but insignificant when each scattering angle is 40 deg. or greater and (ii) insignificant in the np{gamma} process for all scattering angles. The nn{gamma} cross sections for the TuTts and Low amplitudes differ substantially for the kinematics investigated. Conclusions: In general, the Low amplitude agrees well with the TuTts amplitude when anomalous magnetic moment effects are not significant, but the two amplitudes can yield

  9. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies

    NASA Astrophysics Data System (ADS)

    Abbott, D.; Adderley, P.; Adeyemi, A.; Aguilera, P.; Ali, M.; Areti, H.; Baylac, M.; Benesch, J.; Bosson, G.; Cade, B.; Camsonne, A.; Cardman, L. S.; Clark, J.; Cole, P.; Covert, S.; Cuevas, C.; Dadoun, O.; Dale, D.; Dong, H.; Dumas, J.; Fanchini, E.; Forest, T.; Forman, E.; Freyberger, A.; Froidefond, E.; Golge, S.; Grames, J.; Guèye, P.; Hansknecht, J.; Harrell, P.; Hoskins, J.; Hyde, C.; Josey, B.; Kazimi, R.; Kim, Y.; Machie, D.; Mahoney, K.; Mammei, R.; Marton, M.; McCarter, J.; McCaughan, M.; McHugh, M.; McNulty, D.; Mesick, K. E.; Michaelides, T.; Michaels, R.; Moffit, B.; Moser, D.; Muñoz Camacho, C.; Muraz, J.-F.; Opper, A.; Poelker, M.; Réal, J.-S.; Richardson, L.; Setiniyaz, S.; Stutzman, M.; Suleiman, R.; Tennant, C.; Tsai, C.; Turner, D.; Ungaro, M.; Variola, A.; Voutier, E.; Wang, Y.; Zhang, Y.; PEPPo Collaboration

    2016-05-01

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19 MeV /c , limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

  10. Thin Object Radiography with a 2.2 MeV Pulsed Power Machine

    NASA Astrophysics Data System (ADS)

    Haines, Todd; Danielson, Jeremy; Wood, W. Monty

    2015-06-01

    An experimental series was performed at a pulsed-power 2.2 MeV flash radiography machine to determine the lower limits of its mass sensitivity. This machine uses a rod-pinch diode with accelerating potential of 2.2 MeV and 50 ns pulse duration. Tungsten, aluminum, and titanium rod anodes were used to tune the emitted bremsstrahlung spectrum; as well as aluminum and beryllium filter materials. Analysis of thin tantalum foils shows a mass sensitivity as low as 300 μg/cm2. This is a factor of 5 better than previous measurements.

  11. Bremsstrahlung and K(alpha) fluorescence measurements for inferring conversion efficiencies into fast ignition relevant hot electrons

    SciTech Connect

    Chen, C D; Patel, P K; Hey, D S; Mackinnon, A J; Key, M H; Akli, K U; Bartal, T; Beg, F N; Chawla, S; Chen, H; Freeman, R R; Higginson, D P; Link, A; Ma, T Y; MacPhee, A G; Stephens, R B; Van Woerkom, L D; Westover, B; Porkolab, M

    2009-07-24

    The Bremsstrahlung and K-shell emission from 1 mm x 1 mm x 1 mm planar targets irradiated by a short-pulse 3 x 10{sup 18}-8 x 10{sup 19} W/cm{sup 2} laser were measured. The Bremsstrahlung was measured using a filter stack spectrometer with spectral discrimination up to 500 keV. K-shell emission was measured using a single photon counting charge coupled device (CCD). From Monte Carlo modeling of the target emission, conversion efficiencies into 1-3 MeV electrons of 3-12%, representing 20-40% total conversion efficiencies were inferred for intensities up to 8 x 10{sup 19} W/cm{sup 2}. Comparisons to scaling laws using synthetic energy spectra generated from the intensity distribution of the focal spot imply slope temperatures less than the ponderomotive potential of the laser. Resistive transport effects may result in potentials of a few hundred kV in the first few tens of microns in the target. This would lead to higher total conversion efficiencies than inferred from Monte Carlo modeling but lower conversion efficiencies into 1-3 MeV electrons.

  12. Excitation of 11/2- isomeric state in 137Ce in (γ,n) reaction within 10-22MeV energy range

    NASA Astrophysics Data System (ADS)

    Mazur, V. M.; Bigan, Z. M.; Derechkey, P. S.; Symochko, D. M.

    2016-09-01

    Isomeric yields ratios and energy differential cross-section of metastable state excitation in the 138Ce(γ,n)137m,gCe reaction has been studied in the 10-22MeV end-point energy range of bremsstrahlung beams. Experimental data are compared with Hauser-Feshbach calculations performed with TALYS-1.6 statistical model code.

  13. Bremsstrahlung emission of the SN1987A interior

    NASA Technical Reports Server (NTRS)

    The, Lih-Sin; Clayton, Donald D.

    1991-01-01

    The down-scattering of gamma photons stores a significant fraction of the total energy in recoil electrons. This paper presents the bremsstrahlung emission of those recoil electrons in SN1987A. If the bolometric luminosity derives from radioactive decay, the bremsstrahlung emissivity must be present, but has not previously been treated. Initially it was our hope to account for the Ginga 16-28 keV measurement of SN1987A or to find a detectable X-ray luminosity near 1 keV for ROSAT. Although this bremsstrahlung emission fails to explain Ginga fluxes, it dominates the X-ray fluxes below 20 keV and can have detectable consequences for the X-ray lines from circumstellar matter. Results for day 175, 500, 1000, and 1500 are shown.

  14. Enhancing Bremsstrahlung production from ultraintense laser-solid interactions with front surface structures

    NASA Astrophysics Data System (ADS)

    Jiang, Sheng; Krygier, Andrew G.; Schumacher, Douglass W.; Akli, Kramer U.; Freeman, Richard R.

    2014-10-01

    We report the results of a combined study of particle-in-cell and Monte Carlo modeling that investigates the production of Bremsstrahlung radiation produced when an ultraintense laser interacts with a tower-structured target. These targets are found to significantly narrow the electron angular distribution as well as produce significantly higher energies. These features combine to create a significant enhancement in directionality and energy of the Bremstrahlung radiation produced by a high-Z converter target. These studies employ short-pulse, high intensity laser pulses, and indicate that novel target design has potential to greatly enhance the yield and narrow the directionality of high energy electrons and γ-rays. We find that the peak γ-ray brightness for this source is 6.0 × 1019 s-1 mm-2 mrad-2 at 10 MeV and 1.4 × 1019 s-1 mm-2 mrad-2 at 100 MeV (0.1% bandwidth). Contribution to the Topical Issue "X-ray generation from ultrafast lasers", edited by Germán J. de Valcárcel, Luis Roso and Amelle Zaïr.

  15. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies

    SciTech Connect

    Faddegon, Bruce A.; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc

    2008-10-15

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10-30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10-30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90 degree sign for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30 degree sign , 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30 degree sign was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10 degree sign ), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2-3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the ''low energy

  16. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies

    PubMed Central

    Faddegon, Bruce A.; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc

    2008-01-01

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10–30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10–30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90° for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30°, 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30° was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10°), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2–3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the “low energy” physics list were more accurate than

  17. Benchmarking of Monte Carlo simulation of bremsstrahlung from thick targets at radiotherapy energies.

    PubMed

    Faddegon, Bruce A; Asai, Makoto; Perl, Joseph; Ross, Carl; Sempau, Josep; Tinslay, Jane; Salvat, Francesc

    2008-10-01

    Several Monte Carlo systems were benchmarked against published measurements of bremsstrahlung yield from thick targets for 10-30 MV beams. The quantity measured was photon fluence at 1 m per unit energy per incident electron (spectra), and total photon fluence, integrated over energy, per incident electron (photon yield). Results were reported at 10-30 MV on the beam axis for Al and Pb targets and at 15 MV at angles out to 90 degrees for Be, Al, and Pb targets. Beam energy was revised with improved accuracy of 0.5% using an improved energy calibration of the accelerator. Recently released versions of the Monte Carlo systems EGSNRC, GEANT4, and PENELOPE were benchmarked against the published measurements using the revised beam energies. Monte Carlo simulation was capable of calculation of photon yield in the experimental geometry to 5% out to 30 degrees, 10% at wider angles, and photon spectra to 10% at intermediate photon energies, 15% at lower energies. Accuracy of measured photon yield from 0 to 30 degrees was 5%, 1 s.d., increasing to 7% for the larger angles. EGSNRC and PENELOPE results were within 2 s.d. of the measured photon yield at all beam energies and angles, GEANT4 within 3 s.d. Photon yield at nonzero angles for angles covering conventional field sizes used in radiotherapy (out to 10 degrees), measured with an accuracy of 3%, was calculated within 1 s.d. of measurement for EGSNRC, 2 s.d. for PENELOPE and GEANT4. Calculated spectra closely matched measurement at photon energies over 5 MeV. Photon spectra near 5 MeV were underestimated by as much as 10% by all three codes. The photon spectra below 2-3 MeV for the Be and Al targets and small angles were overestimated by up to 15% when using EGSNRC and PENELOPE, 20% with GEANT4. EGSNRC results with the NIST option for the bremsstrahlung cross section were preferred over the alternative cross section available in EGSNRC and over EGS4. GEANT4 results calculated with the "low energy" physics list were more

  18. The Stonehenge technique. A method for aligning coherent bremsstrahlung radiators

    NASA Astrophysics Data System (ADS)

    Livingston, Ken

    2009-05-01

    This paper describes a technique for the alignment of crystal radiators used to produce high energy, linearly polarized photons via coherent bremsstrahlung scattering at electron beam facilities. In these experiments the crystal is mounted on a goniometer which is used to adjust its orientation relative to the electron beam. The angles and equations which relate the crystal lattice, goniometer and electron beam direction are presented here, and the method of alignment is illustrated with data taken at MAMI (the Mainz microtron). A practical guide to setting up a coherent bremsstrahlung facility and installing new crystals using this technique is also included.

  19. Polarization Bremsstrahlung radiation on a nanosphere in a dielectric

    NASA Astrophysics Data System (ADS)

    Astapenko, V. A.

    2011-11-01

    Within the limits of a new approach based on the Mie scattering theory, polarization bremsstrahlung radiation (PBR), arising during electron scattering on a metallic nanosphere with radius from 10 to 100 nm placed in a dielectric medium is theoretically investigated. The spectral range close to the plasmon resonance is considered, where the contribution of the polarized channel to bremsstrahlung radiation dominates. Spectral, velocity, and angular PBR characteristics are calculated. The sensitivity of the PBR spectrum to the dielectric permittivity of the medium surrounding the nanosphere is demonstrated.

  20. Electron-ion bremsstrahlung continuum emission in nonideal plasmas

    NASA Astrophysics Data System (ADS)

    Valuev, A. A.; Kurilenkov, Iu. K.

    1980-09-01

    The effect of the Coulomb nonidealness of a plasma on bremsstrahlung emission (absorption) over a wide spectral range is analyzed using numerical data on electron dynamics in nonideal fully ionized plasmas with charged-particle densities of 10 to the 18th-20th/cu cm and a temperature of 10,000 K. The results are compared with calculations obtained through Kramers' formula and with values of the bremsstrahlung emission coefficient derived from experimental data on the radiation from dense plasmas. These results point to the fact that relative 'bleaching' of nonideal plasmas occur in the IR region of the spectrum.

  1. Electron-ion bremsstrahlung continuum emission in nonideal plasmas

    NASA Astrophysics Data System (ADS)

    Valuev, A. A.; Kurilenkov, Iu. K.

    1981-03-01

    The effect of the Coulomb nonidealness of a plasma on bremsstrahlung emission (absorption) over a wide spectral range is analyzed using numerical data on electron dynamics in nonideal fully ionized plasmas with charged-particle densities of 10 to the 18th-20th/cu cm and a temperature of 10,000 K. The results are compared with calculations obtained through Kramers' formula and with values of the bremsstrahlung emission coefficient derived from experimental data on the radiation from dense plasmas. These results point to the fact that relative 'bleaching' of nonideal plasmas occur in the IR region of the spectrum.

  2. Saints, sinners and non-believers: the moral space of food. A qualitative exploration of beliefs and perspectives on healthy eating of Irish adults aged 50-70.

    PubMed

    Delaney, Mary; McCarthy, Mary B

    2014-02-01

    Food choices can involve a moral element of which healthy eating has come to play a major part in recent years. This research aimed to explore the moral space of food for older adults in order to understand how they conceptualise and negotiate various moral demands in the context of their general food lives. In-depth interviews on the lived experience of food and eating were conducted with a purposive sample of 50 adults aged 50-70, who varied by dietary quality and health status. An inductive thematic analysis was carried out. Three major themes representing aspects of the "moral space of food" were identified. This moral space was influenced by old religious and secular moralities which have become intertwined with new moralities of "healthism", a trend towards encouraging personal responsibility for health. Participants sought to maintain moral congruence by keeping their behaviour within moral boundaries through balance and moderation. Some resisted immoral positioning by highlighting their own autonomy or by challenging healthist ideology. A fundamental tension exists between the concept of healthy eating as desirable to remain a moral person while simultaneously being equated with sacrifice of pleasure and enjoyment. Healthist ideology perpetuates this tension, problematising enjoyment of food and bodies of those outside of the "norm". Attempting to address negative moralistic undertones of healthy eating messages may help to engage public interest in nutrition.

  3. Evaluation of the antioxidant capacity of a milk protein matrix in vitro and in vivo in women aged 50-70 years.

    PubMed

    Power-Grant, Orla; McCormack, William G; Ramia De Cap, Maximiliano; Amigo-Benavent, Miryam; Fitzgerald, Richard J; Jakeman, Phil

    2016-01-01

    Bovine milk proteins have emerged as a novel, dairy-based source of dietary antioxidants and a component of a nutritional strategy to maintain muscle mass during ageing. The aim of this study was to characterise the in vitro antioxidant capacity (AOC) of a milk-based protein matrix (MPM) before and after simulated gastrointestinal digestion (SGID) and determine whether plasma AOC was similarly modified in vivo following acute ingestion of the MPM in healthy 50-70 years old women. To achieve this, the AOC of the MPM was measured by the oxygen radical absorbance capacity (ORAC) assay prior to and following SGID. In parallel, plasma obtained from women prior to and for 3 h following ingestion of the MPM was analysed ex vivo for change in AOC to evaluate the translation in vivo. SGID of the MPM increased AOC by ∼ 35% (27,365 ± 2152 versus 42,592 ± 2299 μmol TE/100 g dw; p < 0.05). Sampled ex vivo, ingestion of the MPM increased fasting plasma AOC by ∼ 23% (10,952 ± 751 to 13,519 ± 800 μmol TE/L; p < 0.05). These data provide preliminary evidence of an association between the change in the ORAC-based measurement of AOC of an MPM subjected to simulated digest in vitro and the change in plasma AOC following ingestion of the MPM sampled ex vivo from healthy elderly women. PMID:26960816

  4. Comparing Solar-Flare Acceleration of >-20 MeV Protons and Electrons Above Various Energies

    NASA Technical Reports Server (NTRS)

    Shih, Albert Y.

    2010-01-01

    A large fraction (up to tens of percent) of the energy released in solar flares goes into accelerated ions and electrons, and studies indicate that these two populations have comparable energy content. RHESSI observations have shown a striking close linear correlation between the 2.223 MeV neutron-capture gamma-ray line and electron bremsstrahlung emission >300 keV, indicating that the flare acceleration of >^20 MeV protons and >300 keV electrons is roughly proportional over >3 orders of magnitude in fluence. We show that the correlations of neutron-capture line fluence with GOES class or with bremsstrahlung emission at lower energies show deviations from proportionality, primarily for flares with lower fluences. From analyzing thirteen flares, we demonstrate that there appear to be two classes of flares with high-energy acceleration: flares that exhibit only proportional acceleration of ions and electrons down to 50 keV and flares that have an additional soft, low-energy bremsstrahlung component, suggesting two separate populations of accelerated electrons. We use RHESSI spectroscopy and imaging to investigate a number of these flares in detail.

  5. Determination of Endpoint Energy and Bremsstrahlung Spectra for High-Energy Radiation-Therapy Beams

    NASA Astrophysics Data System (ADS)

    Landry, Danny Joe

    Few attempts have been made to experimentally determine thick-target bremsstrahlung spectra of megavoltage therapy beams. For spectral studies using the Compton scattering technique, sodium iodine (NaI) detectors with relatively poor energy resolution have been used. Other experimental techniques for determining spectra are generally not suited for a clinical environment with the inherent time and space constraints. To gather more spectral information than previously obtained in the region near the endpoint energy, the use of a high-resolution intrinsic-germanium (Ge) detector was proposed. A response function matrix was determined from experimentally obtained pulse height distributions on the multichannel analyzer. The distributions were for nine various monoenergetic sources between 280 adn 1525 keV. The response function was used to convert the measured pulse height distributions to photon flux spectra using an iterative approximation technique with a computer. Photon flux spectra from the Sagittaire Linear Accelerator were obtained at average-electron endpoint energies of 15, 20, and 25 MeV. Two spectra were measured at the 25 MeV setting; one spectrum was measured along the central axis and one spectrum at 4(DEGREES) off axis. Photon spectra were also obtained for a Van de Graaff generator at the nominal endpoint energies of 2.2, 2.35, and 2.5 MeV. The results for both the linac and the Van de Graaff generator were compared with theoretical spectra and previously measured spectra where available. Also, photon spectra from a Theratron-80 (('60)Co) unit were determined for three field sizes and for a 10 x 10 cm. field with a lucite tray or a 45(DEGREES) wedge in the beam. The resulting spectra were compared to previously measured ('60)Co spectra.

  6. The LPM effect in sequential bremsstrahlung 2: factorization

    NASA Astrophysics Data System (ADS)

    Arnold, Peter; Chang, Han-Chih; Iqbal, Shahin

    2016-09-01

    The splitting processes of bremsstrahlung and pair production in a medium are coherent over large distances in the very high energy limit, which leads to a suppression known as the Landau-Pomeranchuk-Migdal (LPM) effect. In this paper, we continue analysis of the case when the coherence lengths of two consecutive splitting processes overlap (which is important for understanding corrections to standard treatments of the LPM effect in QCD), avoiding soft-gluon approximations. In particular, this paper analyzes the subtle problem of how to precisely separate overlapping double splitting (e.g. overlapping double bremsstrahlung) from the case of consecutive, independent bremsstrahlung (which is the case that would be implemented in a Monte Carlo simulation based solely on single splitting rates). As an example of the method, we consider the rate of real double gluon bremsstrahlung from an initial gluon with various simplifying assumptions (thick media; q approximation; large N c; and neglect for the moment of processes involving 4-gluon ver-tices) and explicitly compute the correction Δ dΓ /dx dy due to overlapping formation times.

  7. Large efficiency improvements in BEAMnrc using directional bremsstrahlung splitting

    SciTech Connect

    Kawrakow, I.; Rogers, D.W.O.; Walters, B.R.B.

    2004-10-01

    The introduction into the BEAMnrc code of a new variance reduction technique, called directional bremsstrahlung splitting (DBS), is described. DBS uses a combination of interaction splitting for bremsstrahlung, annihilation, Compton scattering, pair production and photoabsorption, and Russian Roulette to achieve a much better efficiency of photon beam treatment head simulations compared to the splitting techniques already available in BEAMnrc (selective bremsstrahlung splitting, SBS, and uniform bremsstrahlung splitting, UBS). In a simulated 6 MV photon beam (10x10 cm{sup 2} field) photon fluence efficiency in the beam using DBS is over 8 times higher than with optimized SBS and over 20 times higher than with UBS, with a similar improvement in electron fluence efficiency in the beam. Total dose efficiency in a central-axis depth-dose curve improves by a factor of 6.4 over SBS at all depths in the phantom. The performance of DBS depends on the details of the accelerator being simulated. At higher energies, the relative improvement in efficiency due to DBS decreases somewhat, but is still a factor of 3.5 improvement over SBS for total dose efficiency using DBS in a simulated 18 MV photon beam. Increasing the field size of the simulated 6 MV beam to 40x40 cm{sup 2} (broad beam) causes the relative efficiency improvement of DBS to decrease by a factor of {approx_equal}1.7 but is still up to 7 times more efficient than with SBS.

  8. Neutrino signals from electroweak bremsstrahlung in solar WIMP annihilation

    SciTech Connect

    Bell, Nicole F.; Brennan, Amelia J.; Jacques, Thomas D. E-mail: a.brennan@pgrad.unimelb.edu.au

    2012-10-01

    Bremsstrahlung of W and Z gauge bosons, or photons, can be an important dark matter annihilation channel. In many popular models in which the annihilation to a pair of light fermions is helicity suppressed, these bremsstrahlung processes can lift the suppression and thus become the dominant annihilation channels. The resulting dark matter annihilation products contain a large, energetic, neutrino component. We consider solar WIMP annihilation in the case where electroweak bremsstrahlung dominates, and calculate the resulting neutrino spectra. The flux consists of primary neutrinos produced in processes such as χχ→ν-bar νZ and χχ→ν-bar lW, and secondary neutrinos produced via the decays of gauge bosons and charged leptons. After dealing with the neutrino propagation and flavour evolution in the Sun, we consider the prospects for detection in neutrino experiments on Earth. We compare our signal with that for annihilation to W{sup +}W{sup −}, and show that, for a given annihilation rate, the bremsstrahlung annihilation channel produces a larger signal by a factor of a few.

  9. Absolute doubly differential bremsstrahlung cross sections from rare gas atoms

    NASA Astrophysics Data System (ADS)

    Portillo, Salvador

    The absolute doubly differential bremsstrahlung cross section has been measured for 28 and 50 keV electrons incident on the rare gases Xe, Kr, Ar and Ne. The cross sections are differential with respect to energy and photon emission. A SiLi solid state detector measured data at 90° with respect to the beam line. A thorough analysis of the experimental systematic error yielded a high degree of confidence in the experimental data. The absolute bremsstrahlung doubly differential cross sections provided for a rigorous test of the normal bremsstrahlung theory, tabulated by Kissel, Quarles and Pratt1 (KQP) and of the SA theory2 that includes the contribution from polarization bremsstrahlung. To test the theories a comparison of the overall magnitude of the cross section as well as comparison of the photon energy dependence was carried out. The KQP theoretical values underestimated the magnitude of the cross section for all targets and for both energies. The SA values were in excellent agreement with the 28 keV data. For the 50keV data the fit was also very good. However, there were energy regions where there was a small discrepancy between the theory and the data. This suggests that the Polarization Bremsstrahlung (PB) mechanism does contribute to the overall spectrum and is detectable in this parameter space. 1Kissel, L., Quarles, C. A., Pratt, R. H., Atom. Data Nucl. Data Tables 28, 381 (1983). 2Avdonina N. B., Pratt, R. H., J. Phys. B: At. Mol. Opt. Phys. 32 4261 (1999).

  10. Enhancement of Majorana dark matter annihilation through Higgs bremsstrahlung

    SciTech Connect

    Luo, Feng; You, Tevong E-mail: tevong.you@kcl.ac.uk

    2013-12-01

    For Majorana dark matter, gauge boson bremsstrahlung plays an important role in enhancing an otherwise helicity-suppressed s-wave annihilation cross-section. This is well known for processes involving a radiated photon or gluon together with a Standard Model fermion-antifermion pair, and the case of massive electroweak gauge bosons has also recently been studied. Here we show that internal Higgs bremsstrahlung also lifts helicity suppression and could be the dominant contribution to the annihilation rate in the late Universe for dark matter masses below ∼ 1 TeV. Using a toy model of leptophilic dark matter, we calculate the annihilation cross-section into a lepton-antilepton pair with a Higgs boson and investigate the energy spectra of the final stable particles at the annihilation point.

  11. Bremsstrahlung from nuclear scattering at low energy near a resonance

    NASA Astrophysics Data System (ADS)

    Trail, C. C.; Lesser, P. M. S.; Liou, M. K.

    1984-04-01

    A program to contribute to the general understanding of nuclear reactions by determining as many of the off-shell properties of the proton-nucleus interaction as possible through the study of the proton-nucleus bremsstrahlung process is discussed. The limits of validity of a model independent analysis of these reactions in the neighborhood of a resonance or a breakup threshold are sought. The differences between this analysis and the data is utilized to elucidate those off-shell constraints which any valid proton-nucleus model interaction must satisfy. The bremsstrahlung process provides a method for determining the off-shell properties of the proton-nucleus potential, and the Brooklyn College program offers a unique opportunity to measure these crucial aspects of the low energy proton-nucleus interaction.

  12. The n-p bremsstrahlung in heavy ion collision processes

    NASA Astrophysics Data System (ADS)

    Blann, M.

    1990-01-01

    The goal is to summarize the current status of the interpretation of energetic gamma-rays in heavy ion collisions via the n-p-bremsstrahlung mechanism. An essential element of the topic is a transport equation to approximate the fast non-equilibrium nucleon-nucleon cascade/emission stage of the heavy ion reactions. It is during this stage that it was expected that the n-p-bremsstrahlung processes produced energetic photons. The Boltzmann master equation (BME) model which will be used as the transport code is briefly described, deferring to earlier works for a more complete description, and present but a single representative comparison with an experimental neutron emission spectrum. The status of the elementary n-p-gamma cross section needed to extend the transport code to photon emission in heavy ion reactions, and the status of these comparisons with data are summarized.

  13. Feasibility studies of the diffractive bremsstrahlung measurement at the LHC

    NASA Astrophysics Data System (ADS)

    Chwastowski, Janusz J.; Czekierda, Sabina; Kycia, Radosław; Staszewski, Rafał; Turnau, Jacek; Trzebiński, Maciej

    2016-06-01

    Feasibility studies of an observation of the exclusive diffractive bremsstrahlung in proton-proton scattering at the centre of mass energy 13 TeV at the LHC are reported. These studies aim at the dedicated data taking periods with low instantaneous luminosity delivered by the LHC where the pile-up interactions can be neglected. A simplified approach to the photon and the scattered proton energy reconstruction is used. The background influence is discussed.

  14. Loopy constraints on leptophilic dark matter and internal bremsstrahlung

    SciTech Connect

    Kopp, Joachim; Michaels, Lisa; Smirnov, Juri E-mail: lisa.michaels@mpi-hd.mpg.de

    2014-04-01

    A sharp and spatially extended peak in an astrophysical gamma ray spectrum would provide very strong evidence for the existence of dark matter (DM), given that there are no known astrophysical processes that could mimic such a signal. From the particle physics perspective, perhaps the simplest explanation for a gamma ray peak is internal bremsstrahlung in DM annihilation through a charged t-channel mediator η close in mass to the DM particle χ. Since DM annihilation to quarks is already tightly constrained in this scenario, we focus here on the leptophilic case. We compute the electromagnetic anapole and dipole moments that DM acquires at 1-loop, and we find an interesting enhancement of these moments if the DM particle and the mediator are close in mass. We constrain the DM anapole and dipole moments using direct detection data, and then translate these limits into bounds on the DM annihilation cross section. Our bounds are highly competitive with those from astrophysical gamma ray searches. In the second part of the paper, we derive complementary constraints on internal bremsstrahlung in DM annihilation using LEP mono-photon data, measurements of the anomalous magnetic moments of the electron and the muon, and searches for lepton flavor violation. We also comment on the impact of the internal bremsstrahlung scenario on the hyperfine splitting of true muonium.

  15. Scintillating fiber array for tagging post-bremsstrahlung electrons

    NASA Astrophysics Data System (ADS)

    Cole, Philip; Alef, Stefan; Reitz, Björn-Eric; Schmieden, Hartmut; Hannappel, Jürgen; Jude, Thomas; Sandri, Paolo Levi; BGO-OD Collaboration

    2016-03-01

    We seek to extract the kinematic fingerprints of baryon resonances by making use of a high-quality beam of linearly polarized photons at the BGO-OD experiment at ELSA (Bonn, German). We constructed a unique device for precisely determining the degree of polarization in the coherent bremsstrahlung peak. Deflection of post-bremsstrahlung electrons in the magnetic field of the photon tagger provides precise information on the energy and polarization of the bremsstrahlung photons. And thereby will constrain the overall kinematics of the final-state particles in all decay channels of the photoproduced baryon resonances. We designed, prototyped, built, calibrated, and have been operating a three-layered, multi-stranded, scintillating-fiber detector for ensuring the quality of the linearly polarization of the photon beam. The overlapping 2.00-mm scintillating fibers form an array giving ARGUS over 500 channels. The very befitting name harkens to the mythological all-seeing creature Argus Panoptes, the multi-eyed giant. Our work was supported through a Fulbright Scholarship Award and by the Deutsche Forschungsgemeinschaft through the Collaborative Research Center (Sonderforschungsbereich SFB/TR-16) of the universities in Bonn, Giessen and Bochum, Germany. NSF-PHY-1307340.

  16. Photoactivation of 176mLu via Bremsstrahlung at the Stuttgart DYNAMITRON

    NASA Astrophysics Data System (ADS)

    Goddard, Brian; Henry, Tom; Balint, Trevor; Pitz, Heinz-Hermann; Stedile, Frank; Kneissl, Ulrich; Gaison, Jeremy; Winick, Tristan; Carroll, James

    2014-09-01

    Though unstable, the ground state of 176Lu has a very long half-life of approximately 37 billion years and primarily β- decays (>99.9%) to 176Hf. However, 176Lu possesses an isomer (Jπ = 7-) 123 keV above the ground state (Jπ = 1-) that also β- decays to 176Hf but with a much shorter half-life of about 3.6 hours. The study of this isomer could lead to new findings regarding astrophysical nucleosynthesis. A disparity between the predicted abundance of 176Lu due to nucleosynthesis and the actual measured abundance implies that transitions from the isomer to the ground state via intermediate states must have taken place during the s-process. Since the rates at which these transitions occur are temperature dependent, 176Lu could be used as an s-process ``thermometer.'' A photoactivation experiment was performed on 176Lu at the Stuttgart DYNAMITRON using bremsstrahlung with varying endpoints between 0.7 and 2.2 MeV to determine the intermediate state energies and integral cross sections for the transitions that lead to the isomer. We present the results of the analysis of the data as well as preliminary values for the intermediate state energies and their cross sections.

  17. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies

    DOE PAGESBeta

    Abbott, D.; Adderley, P.; Adeyemi, A.; Aguilera, P.; Ali, M.; Areti, H.; Baylac, M.; Benesch, J.; Bosson, G.; Cade, B.; et al

    2016-05-27

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19~MeV/c, limited only by the electron beam polarization. We report that this technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

  18. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies.

    PubMed

    Abbott, D; Adderley, P; Adeyemi, A; Aguilera, P; Ali, M; Areti, H; Baylac, M; Benesch, J; Bosson, G; Cade, B; Camsonne, A; Cardman, L S; Clark, J; Cole, P; Covert, S; Cuevas, C; Dadoun, O; Dale, D; Dong, H; Dumas, J; Fanchini, E; Forest, T; Forman, E; Freyberger, A; Froidefond, E; Golge, S; Grames, J; Guèye, P; Hansknecht, J; Harrell, P; Hoskins, J; Hyde, C; Josey, B; Kazimi, R; Kim, Y; Machie, D; Mahoney, K; Mammei, R; Marton, M; McCarter, J; McCaughan, M; McHugh, M; McNulty, D; Mesick, K E; Michaelides, T; Michaels, R; Moffit, B; Moser, D; Muñoz Camacho, C; Muraz, J-F; Opper, A; Poelker, M; Réal, J-S; Richardson, L; Setiniyaz, S; Stutzman, M; Suleiman, R; Tennant, C; Tsai, C; Turner, D; Ungaro, M; Variola, A; Voutier, E; Wang, Y; Zhang, Y

    2016-05-27

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19  MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community. PMID:27284661

  19. Production of Highly Polarized Positrons Using Polarized Electrons at MeV Energies.

    PubMed

    Abbott, D; Adderley, P; Adeyemi, A; Aguilera, P; Ali, M; Areti, H; Baylac, M; Benesch, J; Bosson, G; Cade, B; Camsonne, A; Cardman, L S; Clark, J; Cole, P; Covert, S; Cuevas, C; Dadoun, O; Dale, D; Dong, H; Dumas, J; Fanchini, E; Forest, T; Forman, E; Freyberger, A; Froidefond, E; Golge, S; Grames, J; Guèye, P; Hansknecht, J; Harrell, P; Hoskins, J; Hyde, C; Josey, B; Kazimi, R; Kim, Y; Machie, D; Mahoney, K; Mammei, R; Marton, M; McCarter, J; McCaughan, M; McHugh, M; McNulty, D; Mesick, K E; Michaelides, T; Michaels, R; Moffit, B; Moser, D; Muñoz Camacho, C; Muraz, J-F; Opper, A; Poelker, M; Réal, J-S; Richardson, L; Setiniyaz, S; Stutzman, M; Suleiman, R; Tennant, C; Tsai, C; Turner, D; Ungaro, M; Variola, A; Voutier, E; Wang, Y; Zhang, Y

    2016-05-27

    The Polarized Electrons for Polarized Positrons experiment at the injector of the Continuous Electron Beam Accelerator Facility has demonstrated for the first time the efficient transfer of polarization from electrons to positrons produced by the polarized bremsstrahlung radiation induced by a polarized electron beam in a high-Z target. Positron polarization up to 82% have been measured for an initial electron beam momentum of 8.19  MeV/c, limited only by the electron beam polarization. This technique extends polarized positron capabilities from GeV to MeV electron beams, and opens access to polarized positron beam physics to a wide community.

  20. Internal bremsstrahlung signatures in light of direct dark matter searches

    SciTech Connect

    Garny, Mathias; Ibarra, Alejandro; Pato, Miguel; Vogl, Stefan E-mail: ibarra@tum.de E-mail: stefan.vogl@tum.de

    2013-12-01

    Although proposed long ago, the search for internal bremsstrahlung signatures has only recently been made possible by the excellent energy resolution of ground-based and satellite-borne gamma-ray instruments. Here, we investigate thoroughly the current status of internal bremsstrahlung searches in light of the results of direct dark matter searches and in the framework of a minimal mass-degenerate scenario consisting of a Majorana dark matter particle that couples to a fermion and a scalar via a Yukawa coupling. The upper limits on the annihilation cross section set by Fermi-LAT and H.E.S.S. extend uninterrupted from tens of GeV up to tens of TeV and are rather insensitive to the mass degeneracy in the particle physics model. In contrast, direct searches are best in the moderate to low mass splitting regime, where XENON100 limits overshadow Fermi-LAT and H.E.S.S. up to TeV masses if dark matter couples to one of the light quarks. In our minimal scenario we examine carefully the prospects for GAMMA-400, CTA and XENON1T, all planned to come online in the near future, and find that: (a) CTA and XENON1T are fully complementary, with CTA most sensitive to multi-TeV masses and mass splittings around 10%, and XENON1T probing best small mass splittings up to TeV masses; and (b) current constraints from XENON100 already preclude the observation of any spectral feature with GAMMA-400 in spite of its impressive energy resolution, unless dark matter does not couple predominantly to light quarks. Finally, we point out that, unlike for direct searches, the possibility of detecting thermal relics in upcoming internal bremsstrahlung searches requires, depending on the concrete scenario, boost factors larger than 5–10.

  1. On polarization of transition bremsstrahlung in a weakly gyrotropic plasma

    NASA Astrophysics Data System (ADS)

    Korsakov, V. B.; Fleishman, G. D.

    1995-09-01

    The degree of polarization of transition bremsstrahlung (TBS) is calculated in a plasma with weak gyrotropy. The cases of weak and strong Faraday rotation in a radiation source are discussed. The distribution of polarization is shown to have no azimuthal symmetry, if the particle gyroradius is larger than the source size. We calculate the polarization degree of TBS for an ensemble of fast particles and show that polarization exceeds the respective value for transition radiation in the presence of nonthermal inhomogeneities of the plasma density.

  2. Study of 1s internal bremsstrahlung spectrum from 57Co

    NASA Astrophysics Data System (ADS)

    Raghavendra, M. K.; Azeez, Syed; Ramaswamy, C. R.; Umesh, T. K.; Gowda, Ramakrishna

    2002-07-01

    The internal bremsstrahlung contribution from the electron capture of 57Co has been measured in coincidence with K-X-ray of the residual atom. The end-point energy (EPE) is extracted from the data using the linearised Jauch plot. The transition energy obtained using the (EPE) is 842.7 keV, which is close to the value given by Audi and Wapstra. The measured intensity and shape factor from 300 to 600 keV are found to be in good agreement with the Glauber and Martin theory.

  3. Secondary-electron-bremsstrahlung imaging for proton therapy

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Mitsutaka; Nagao, Yuto; Ando, Koki; Yamamoto, Seiichi; Toshito, Toshiyuki; Kataoka, Jun; Kawachi, Naoki

    2016-10-01

    A feasibility study on an imaging technique of a therapeutic proton-beam trajectory using a gamma camera by measuring secondary electron bremsstrahlung (SEB) was performed by means of Monte Carlo simulations and a beam-irradiation experiment. From the simulation and experimental results, it was found that a significant amount of SEB yield exists between the beam-injection surface and the range position along the beam axis and the beam trajectory is clearly imaged by the SEB yield. It is concluded that the SEB imaging is a promising technique for monitoring of therapeutic proton-beam trajectories.

  4. Relativistic Calculation of the Two-Photon Bremsstrahlung Process

    NASA Astrophysics Data System (ADS)

    Fedorova, T. A.; Korol, A. V.; Solovjev, I. A.

    We present analytical and numerical results on the relativistic calculation of the two-photon bremsstrahlung process. For the approximate calculation of relativistic free-free two-photon matrix elements in the central field, we applied the method based on the accurate treatment of the diagonal singularities in the relativistic free-free single-photon matrix elements. Numerical calculations are carried out with the Furry-Sommerfeld-Maue wave functions. The obtained results are compared with the results of the relativistic Born approximation.

  5. Observations of 1-30 MeV gamma rays from the galactic center

    NASA Technical Reports Server (NTRS)

    Zanrosso, E.; Long, J. L.; Zych, A. D.; White, R. S.

    1981-01-01

    Preliminary results are reported for gamma ray observations of the galactic center region made during a 15-hour balloon flight from Alice Springs, Australia on April 18, 1979. The observations were carried out with the UGR double-scatter gamma-ray telescope at energies of 1 to 30 MeV. The observations are compatible with a galactic source of approximately equal brightness along the region of system II galactic longitudes between 300 and 60 deg. The energy distribution joins smoothly to previous spark chamber results at energies above 30 MeV and to scintillator results below 1 MeV. It appears to be a combination of nuclear gamma ray lines superimposed on a power-law bremsstrahlung spectrum. The metastable C-12 line at 4.4 MeV appears to be present with a significance of about 16 standard deviations. The flux in the line is 0.0006 + or - 0.0003 photons/sq cm per sec per rad. The oxygen line at 6.1 MeV does not seem to appear significantly above background.

  6. Nuclear reactions with 14 MeV neutrons and bremsstrahlungs in giant dipole resonance (GDR) region using small accelerators

    NASA Astrophysics Data System (ADS)

    Thiep, Tran Duc; Van Do, Nguyen; An, Truong Thi; Son, Nguyen Ngoc

    2003-07-01

    In 1974 an accelerator of deterium, namely neutron generator NA-3-C was put into operation and in 1982 another accelerator of electron Microtron MT-17 started its work in the Institute of Physics. Though very modest these accelerators are useful for developing countries as Vietnam in both Nuclear Physics Research and Training. In this report we present some results obtained in studies on Nuclear Data, Nuclear Reactions as well as nuclear activation analysis methods. We also would like to discuss about the possibilities of collaboration in the future.

  7. Molecular bremsstrahlung radiation at GHz frequencies in air

    NASA Astrophysics Data System (ADS)

    Al Samarai, Imen; Bérat, Corinne; Deligny, Olivier; Letessier-Selvon, Antoine; Montanet, François; Settimo, Mariangela; Stassi, Patrick

    2016-03-01

    A detection technique for ultra-high-energy cosmic rays, complementary to the fluorescence technique, would be the use of the molecular bremsstrahlung radiation emitted by low-energy ionization electrons left after the passage of the showers in the atmosphere. In this article, a detailed estimate of the spectral intensity of photons at ground level originating from this radiation is presented. The spectral intensity expected from the passage of the high-energy electrons of the cascade is also estimated. The absorption of the photons in the plasma of electrons and neutral molecules is shown to be negligible. The obtained spectral intensity is shown to be 2 ×1 0-21 W cm-2 GHz-1 at 10 km from the shower core for a vertical shower induced by a proton of 1 017.5 eV . In addition, a recent measurement of bremsstrahlung radiation in air at gigahertz frequencies from a beam of electrons produced at 95 keV by an electron gun is also discussed and reasonably reproduced by the model.

  8. Temperature diagnostics of ECR plasma by measurement of electron bremsstrahlung

    SciTech Connect

    Kasthurirangan, S.; Agnihotri, A. N.; Desai, C. A.; Tribedi, L. C.

    2012-07-15

    The x-ray bremsstrahlung spectrum emitted by the electron population in a 14.5 GHz ECR plasma source has been measured using a NaI(Tl) detector, and hence the electron temperature of the higher energy electron population in the plasma has been determined. The x-ray spectra for Ne and Ar gases have been systematically studied as a function of inlet gas pressure from 7 Multiplication-Sign 10{sup -7} mbar to 7 Multiplication-Sign 10{sup -5} mbar and for input microwave power {approx}1 W to {approx}300 W. At the highest input power and optimum pressure conditions, the end point bremsstrahlung energies are seen to reach {approx}700 keV. The estimated electron temperatures (T{sub e}) were found to be in the range 20 keV-80 keV. The T{sub e} is found to be peaking at a pressure of 1 Multiplication-Sign 10{sup -5} mbar for both gases. The T{sub e} is seen to increase with increasing input power in the intermediate power region, i.e., between 100 and 200 W, but shows different behaviour for different gases in the low and high power regions. Both gases show very weak dependence of electron temperature on inlet gas pressure, but the trends in each gas are different.

  9. Elastic photonuclear cross sections for bremsstrahlung from relativistic ions

    NASA Astrophysics Data System (ADS)

    Mikkelsen, Rune E.; Sørensen, Allan H.; Uggerhøj, Ulrik I.

    2016-04-01

    In this paper, we provide a procedure to calculate the bremsstrahlung spectrum for virtually any relativistic bare ion with charge 6e or beyond, Z ⩾ 6 , in ultraperipheral collisions with target nuclei. We apply the Weizsäcker-Williams method of virtual quanta to model the effect of the distribution of nuclear constituents on the interaction of the ion with the radiation target. This leads to a bremsstrahlung spectrum peaking at 2 γ times the energy of the giant dipole resonance (γ is the projectile energy in units of its rest energy). A central ingredient in the calculation is the cross section for elastic scattering of photons on the ion. This is only available in the literature for a few selected nuclei and, usually, only in a rather restricted parameter range. Hence we develop a procedure applicable for all Z ⩾ 6 to estimate the elastic scattering. The elastic cross section is obtained at low to moderate photon energies, somewhat beyond the giant dipole resonance, by means of the optical theorem, a dispersion relation, and data on the total absorption cross section. The cross section is continued at higher energies by invoking depletion due to loss of coherence in the scattering. Our procedure is intended for any ion where absorption data is available and for moderate to high energies, γ ≳ 10 .

  10. Rescattering effects in laser-assisted electron-atom bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Zheltukhin, A. N.; Flegel, A. V.; Frolov, M. V.; Manakov, N. L.; Starace, Anthony F.

    2015-04-01

    Rescattering effects in non-resonant spontaneous laser-assisted electron-atom bremsstrahlung (LABrS) are analyzed within the framework of time-dependent effective-range (TDER) theory. It is shown that high energy LABrS spectra exhibit rescattering plateau structures that are similar to those that are well-known in strong field laser-induced processes as well as those that have been predicted theoretically in laser-assisted collision processes. In the limit of a low-frequency laser field, an analytic description of LABrS is obtained from a rigorous quantum analysis of the exact TDER results for the LABrS amplitude. This amplitude is represented as a sum of factorized terms involving three factors, each having a clear physical meaning. The first two factors are the exact field-free amplitudes for electron-atom bremsstrahlung and for electron-atom scattering, and the third factor describes free electron motion in the laser field along a closed trajectory between the first (scattering) and second (rescattering) collision events. Finally, an extension of these TDER results to the case of LABrS in a Coulomb field is discussed.

  11. The Schiff angular bremsstrahlung distribution from composite media

    NASA Astrophysics Data System (ADS)

    Taylor, M. L.; Dalton, B.; Franich, R. D.

    2012-12-01

    The Schiff differential for the angular distribution of bremsstrahlung is widely employed, but calculations involving composite materials (i.e. compounds and mixtures) are often undertaken in a somewhat ad hoc fashion. In this work, we suggest an alternative approach to power-law estimates of the effective atomic number utilising Seltzer and Berger's combined approach in order to generate single-valued effective atomic numbers applicable over a large energy range (in the worst case deviation from constancy of about 2% between 10 keV and 1 GeV). Differences with power-law estimates of Z for composites are potentially significant, particularly for low-Z media such as biological or surrogate materials as relevant within the context of medical physics. As an example, soft tissue differs by >70% and cortical bone differs by >85%, while for high-Z composites such as a tungsten-rhenium alloy the difference is of the order of 1%. Use of the normalised Schiff formula for shape only does not exhibit strong Z dependence. Consequently, in such contexts the differences are negligible - the power-law approach overestimates the magnitude by 1.05% in the case of water and underestimates it by <0.1% for the high-Z alloys. The differences in the distribution are most pronounced for small angles and where the bremsstrahlung quanta are low energy.

  12. Scalar dark matter models with significant internal bremsstrahlung

    SciTech Connect

    Giacchino, Federica; Tytgat, Michel H.G.; Lopez-Honorez, Laura E-mail: llopezho@vub.ac.be

    2013-10-01

    There has been interest recently on particle physics models that may give rise to sharp gamma ray spectral features from dark matter annihilation. Because dark matter is supposed to be electrically neutral, it is challenging to build weakly interacting massive particle models that may accommodate both a large cross section into gamma rays at, say, the Galactic center, and the right dark matter abundance. In this work, we consider the gamma ray signatures of a class of scalar dark matter models that interact with Standard Model dominantly through heavy vector-like fermions (the vector-like portal). We focus on a real scalar singlet S annihilating into lepton-antilepton pairs. Because this two-body final-state annihilation channel is d-wave suppressed in the chiral limit, σ{sub ff-bar}v∝v{sup 4}, we show that virtual internal bremsstrahlung emission of a gamma ray gives a large correction, both today and at the time of freeze-out. For the sake of comparison, we confront this scenario to the familiar case of a Majorana singlet annihilating into light lepton-antilepton pairs, and show that the virtual internal bremsstrahlung signal may be enhanced by a factor of (up to) two orders of magnitude. We discuss the scope and possible generalizations of the model.

  13. Z{sub eff} measurement using extreme ultraviolet bremsstrahlung emission in LHD

    SciTech Connect

    Zhou Hangyu; Dong Chunfeng; Morita, Shigeru; Goto, Motoshi; Yanagibayashi, Jun; Hasuo, Masahiro

    2010-10-15

    Radial profile measurement of Z{sub eff} using visible bremsstrahlung (5300 A) in the Large Helical Device (LHD) has often encountered difficulties because the intensity profile was largely deformed by the nonuniform visible bremsstrahlung emissions from the edge ergodic layer surrounding the core plasma. A space-resolved flat-field extreme ultraviolet (EUV) spectrometer has been newly adopted to measure the Z{sub eff} profile using the EUV bremsstrahlung continuum in the wavelength range of 70-75 A. The EUV bremsstrahlung intensity profiles have been measured and checked for all the magnetic configurations with totally different magnetic field structures in the ergodic layer of LHD. It is found that the nonuniform bremsstrahlung emission from the thick ergodic layer can be entirely eliminated by use of the EUV emission with relatively high photon energy of 170 eV. As a result, the Z{sub eff} profile can be successfully measured for most of discharges regardless of magnetic field structures of the ergodic layer. The Z{sub eff} profiles measured in the EUV range are compared with those measured in the visible range at a magnetic configuration with the thinnest ergodic layer thickness. The result verifies that the use of the EUV bremsstrahlung continuum is an alternative way for the Z{sub eff} measurement in toroidal plasmas with nonuniform bremsstrahlung emissions at the edge. Typical results from the EUV bremsstrahlung measurement are presented showing a fairly flat Z{sub eff} profile with error bars of {+-}14%.

  14. External bremsstrahlung of 90Sr-90Y, 147Pm and 204Tl in detector compounds

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Rudraswamy, B.

    2013-04-01

    External Bremsstrahlung spectra produced by the complete absorption of beta particles from 90Sr to 90Y, 147Pm and 204Tl in nuclear radiation detection compounds like Cesium iodide (CsI) and Sodium Iodide (NaI) has been measured using 0.038 m×0.038 m NaI(Tl) crystal and is compared with Tseng-Pratt theory. The Bremsstrahlung yields are calculated using the unfolded spectra. This paper also describes a new procedure for the calculation of effective absorption coefficient of Bremsstrahlung from the Bremsstrahlung spectra. The measured spectra show fairly good agreement at low energy end of spectrum and some deviation at higher energy end of spectrum with the theory. The measured Bremsstrahlung yields may be useful to apply corrections, whenever beta particle passes through CsI and NaI detectors.

  15. Quasiclassical description of bremsstrahlung accompanying {alpha} decay including quadrupole radiation

    SciTech Connect

    Jentschura, U. D.; Milstein, A. I.; Terekhov, I. S.; Boie, H.; Scheit, H.; Schwalm, D.

    2008-01-15

    We present a quasiclassical theory of {alpha} decay accompanied by bremsstrahlung with a special emphasis on the case of {sup 210}Po, with the aim of finding a unified description that incorporates both the radiation during the tunneling through the Coulomb wall and the finite energy E{sub {gamma}} of the radiated photon up to E{sub {gamma}}{approx}Q{sub {alpha}}/{radical}({eta}), where Q{sub {alpha}} is the {alpha}-decay Q-value and {eta} is the Sommerfeld parameter. The corrections with respect to previous quasiclassical investigations are found to be substantial, and excellent agreement with a full quantum mechanical treatment is achieved. Furthermore, we find that a dipole-quadrupole interference significantly changes the {alpha}-{gamma} angular correlation. We obtain good agreement between our theoretical predictions and experimental results.

  16. The double copy: Bremsstrahlung and accelerating black holes

    NASA Astrophysics Data System (ADS)

    Luna, Andrés; Monteiro, Ricardo; Nicholso, Isobel; O'Connell, Donal; White, Chris D.

    2016-06-01

    Advances in our understanding of perturbation theory suggest the existence of a correspondence between classical general relativity and Yang-Mills theory. A concrete example of this correspondence, which is known as the double copy, was recently intro-duced for the case of stationary Kerr-Schild spacetimes. Building on this foundation, we examine the simple time-dependent case of an accelerating, radiating point source. The gravitational solution, which generalises the Schwarzschild solution, includes a non-trivial stress-energy tensor. This stress-energy tensor corresponds to a gauge theoretic current in the double copy. We interpret both of these sources as representing the radiative part of the field. Furthermore, in the simple example of Bremsstrahlung, we determine a scattering amplitude describing the radiation, maintaining the double copy throughout. Our results provide the strongest evidence yet that the classical double copy is directly related to the BCJ double copy for scattering amplitudes.

  17. Spectra and rates of bremsstrahlung neutrino emission in stars

    NASA Astrophysics Data System (ADS)

    Guo, Gang; Qian, Yong-Zhong

    2016-08-01

    We calculate the energy-differential rate for neutrino emission from electron-nucleus bremsstrahlung in stellar interiors taking into account the effects of electron screening and ionic correlations. We compare the energy-differential and the net rates, as well as the average ν¯e and ν¯x(x =μ ,τ ) energies, for this process with those for e± pair annihilation, plasmon decay, and photoneutrino emission over a wide range of temperature and density. We also compare our updated energy loss rates for the above thermal neutrino emission processes with the fitting formulas widely used in stellar evolution models and determine the temperature and density domain in which each process dominates. We discuss the implications of our results for detection of ν¯e from massive stars during their presupernova evolution and find that pair annihilation makes the predominant contribution to the signal from the thermal emission processes.

  18. Vacuum Cherenkov radiation and bremsstrahlung from disformal couplings

    NASA Astrophysics Data System (ADS)

    van de Bruck, Carsten; Burrage, Clare; Morrice, Jack

    2016-08-01

    The simplest way to modify gravity is to extend the gravitational sector to include an additional scalar degree of freedom. The most general metric that can be built in such a theory includes disformal terms, so that standard model fields move on a metric which is the sum of the space time metric and a tensor constructed from first derivatives of the scalar. In such a theory gravitational waves and photons can propagate at different speeds, and these can in turn be different from the maximum speed limit for matter particles. In this work we show that disformal couplings can cause charged particles to emit Cherenkov radiation and bremsstrahlung apparently in vacuum, depending on the background evolution of the scalar field. We discuss the implications of this for observations of cosmic rays, and the constraints that arise for models of dark energy with disformal couplings.

  19. Electroweak bremsstrahlung for wino-like Dark Matter annihilations

    SciTech Connect

    Ciafaloni, Paolo; Comelli, Denis; Simone, Andrea De; Riotto, Antonio; Urbano, Alfredo E-mail: comelli@fe.infn.it E-mail: antonio.riotto@unige.ch

    2012-06-01

    If the Dark Matter is the neutral Majorana component of a multiplet which is charged under the electroweak interactions of the Standard Model, its main annihilation channel is into W{sup +}W{sup −}, while the annihilation into light fermions is helicity suppressed. As pointed out recently, the radiation of gauge bosons from the initial state of the annihilation lifts the suppression and opens up an s-wave contribution to the cross section. We perform the full tree-level calculation of Dark Matter annihilations, including electroweak bremsstrahlung, in the context of an explicit model corresponding to the supersymmetric wino. We find that the fermion channel can become as important as the di-boson one. This result has significant implications for the predictions of the fluxes of particles originating from Dark Matter annihilations.

  20. Laser radiography forming bremsstrahlung radiation to image an object

    DOEpatents

    Perry, Michael D.; Sefcik, Joseph A.

    2004-01-13

    A method of imaging an object by generating laser pulses with a short-pulse, high-power laser. When the laser pulse strikes a conductive target, bremsstrahlung radiation is generated such that hard ballistic high-energy electrons are formed to penetrate an object. A detector on the opposite side of the object detects these electrons. Since laser pulses are used to form the hard x-rays, multiple pulses can be used to image an object in motion, such as an exploding or compressing object, by using time gated detectors. Furthermore, the laser pulses can be directed down different tubes using mirrors and filters so that each laser pulse will image a different portion of the object.

  1. Neutrino-pair bremsstrahlung from nucleon-nucleon scattering

    DOE PAGESBeta

    Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F.

    2015-07-22

    Background: Neutrino-pair bremsstrahlung processes from nucleon-nucleon scattering ΝΝνν¯ (nnvv¯, ppvv¯, and npvv¯) have recently attracted attention in studies of neutrino emission in neutron stars, because of the implications for the neutron star cooling. The calculated ΝΝνν¯ emissivities within the neutron star environment are relatively insensitive to the two-nucleon dynamical model used in the calculations, but differ significantly from those obtained using an OPE model. Purpose: To investigate the free ΝΝνν¯ cross sections using a realistic nucleon-nucleon scattering amplitude, comparing the relative sizes of the cross sections for the three processes nnvv¯, ppvv¯, and npvv¯.

  2. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    NASA Astrophysics Data System (ADS)

    Dey, R.; Roy, A. C.

    2013-07-01

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Zi = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×108 V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  3. Inverse bremsstrahlung heating rate for dense plasmas in laser fields

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-07-15

    We report a theoretical analysis of inverse bremsstrahlung heating rate in the eikonal approximation. The present analysis is performed for a dense plasma using the screened electron-ion interaction potential for the ion charge state Z{sub i} = 1 and for both the weak and strong plasma screening cases. We have also compared the eikonal results with the first Born approximation (FBA) [M. Moll et al., New J. Phys. 14, 065010 (2012)] calculation. We find that the magnitudes of inverse bremsstrahlung heating rate within the eikonal approximation (EA) are larger than the FBA values in the weak screening case (κ = 0.03 a.u.) in a wide range of field strength for three different initial electron momenta (2, 3, and 4 a.u.). But for strong screening case (κ = 0.3 a.u.), the heating rates predicted by the two approximations do not differ much after reaching their maximum values. Furthermore, the individual contribution of photoemission and photoabsorption processes to heating rate is analysed for both the weak and strong screening cases. We find that the single photoemission and photoabsorption rates are the same throughout the field strength while the multiphoton absorption process dominates over the multiphoton emission process beyond the field strength ≈ 4×10{sup 8} V/cm. The present study of the dependence of heating rate on the screening parameter ranging from 0.01 to 20 shows that whereas the heating rate predicted by the EA is greater than the FBA up to the screening parameter κ = 0.3 a.u., the two approximation methods yield results which are nearly identical beyond the above value.

  4. The influence of Bremsstrahlung induced photoionization for the streamer motion in various gas mixtures

    NASA Astrophysics Data System (ADS)

    Koehn, Christoph; Chanrion, Olivier; Neubert, Torsten

    2016-04-01

    Streamers, the beginning stages of electric discharges, evolve differently depending on their polarity and on the ambient gas composition. One of the well-known supporting mechanisms is "UVphotoionization" where, in air, excited nitrogen emits a UV photon subsequently ionizing oxygen. In pure nitrogen, however, this mechanism is suppressed because of the lack of oxygen; hence this mechanism strongly depends on the ambient gas medium. In this paper we introduce Bremsstrahlung induced photoionization: In the ambient electric field,electrons gain energy and produce Bremsstrahlung photons through the collision with the ambient gas molecules; similarly to "UV-photoionization", the Bremsstrahlung photons ionize the gas molecules and, as such, create electron populations detached from the initial electron patch. For the study of this process we implemented the electron-nucleus Bremsstrahlung process as well as the photoionization by individual photons into an already existing 2.5 D Monte Carlo particle code for the simulation of streamers. We initiated plasma patches of electrons and ions with varying initial electron energies and peak densities in different ambient fields in air and pure nitrogen. We will compare the temporal evolution of the electron densities as well as of the electric field with and without modelling Bremsstrahlung. In air we will test the influence of Bremsstrahlung induced photoionization against "UV-photoionization". We will show that the influence of Bremsstrahlung is negligible in air, but plays a significant role in pure nitrogen at standard temperature and pressure.

  5. Monte Carlo and analytical calculations for characterization of gas bremsstrahlung in ILSF insertion devices

    NASA Astrophysics Data System (ADS)

    Salimi, E.; Rahighi, J.; Sardari, D.; Mahdavi, S. R.; Lamehi Rachti, M.

    2014-12-01

    Gas bremsstrahlung is generated in high energy electron storage rings through interaction of the electron beam with the residual gas molecules in vacuum chamber. In this paper, Monte Carlo calculation has been performed to evaluate radiation hazard due to gas bremsstrahlung in the Iranian Light Source Facility (ILSF) insertion devices. Shutter/stopper dimensions is determined and dose rate from the photoneutrons via the giant resonance photonuclear reaction which takes place inside the shutter/stopper is also obtained. Some other characteristics of gas bremsstrahlung such as photon fluence, energy spectrum, angular distribution and equivalent dose in tissue equivalent phantom have also been investigated by FLUKA Monte Carlo code.

  6. WE-E-18A-05: Bremsstrahlung of Laser-Plasma Interaction at KeV Temperature: Forward Dose and Attenuation Factors

    SciTech Connect

    Saez-Beltran, M; Fernandez Gonzalez, F

    2014-06-15

    Purpose: To obtain an analytical empirical formula for the photon dose source term in forward direction from bremsstrahlung generated from laser-plasma accelerated electron beams in aluminum solid targets, with electron-plasma temperatures in the 10–100 keV energy range, and to calculate transmission factors for iron, aluminum, methacrylate, lead and concrete and air, materials most commonly found in vacuum chamber labs. Methods: Bremsstrahlung fluence is calculated from the convolution of thin-target bremsstrahlung spectrum for monoenergetic electrons and the relativistic Maxwell-Juettner energy distribution for the electron-plasma. Unattenuatted dose in tissue is calculated by integrating the photon spectrum with the mass-energy absorption coefficient. For the attenuated dose, energy dependent absorption coefficient, build-up factors and finite shielding correction factors were also taken into account. For the source term we use a modified formula from Hayashi et al., and we fitted the proportionality constant from experiments with the aid of the previously calculated transmission factors. Results: The forward dose has a quadratic dependence on electron-plasma temperature: 1 joule of effective laser energy transferred to the electrons at 1 m in vacuum yields 0,72 Sv per MeV squared of electron-plasma temperature. Air strongly filters the softer part of the photon spectrum and reduce the dose to one tenth in the first centimeter. Exponential higher energy tail of maxwellian spectrum contributes mainly to the transmitted dose. Conclusion: A simple formula for forward photon dose from keV range temperature plasma is obtained, similar to those found in kilovoltage x-rays but with higher dose per dissipated electron energy, due to thin target and absence of filtration.

  7. Observations of solar flare photon energy spectra from 20 keV to 7 MeV

    NASA Technical Reports Server (NTRS)

    Yoshimori, M.; Watanabe, H.; Nitta, N.

    1985-01-01

    Solar flare photon energy spectra in the 20 keV to 7 MeV range are derived from the Apr. 1, Apr. 4, apr. 27 and May 13, 1981 flares. The flares were observed with a hard X-ray and a gamma-ray spectrometers on board the Hinotori satellite. The results show that the spectral shape varies from flare to flare and the spectra harden in energies above about 400 keV. Effects of nuclear line emission on the continuum and of higher energy electron bremsstrahlung are considered to explain the spectral hardening.

  8. Systematical Analysis on Angular Distribution of Bremsstrahlung Radiation

    SciTech Connect

    Otgooloi, B.; Enkhbat, N.

    2009-03-31

    The systematic analysis has been made the measurement results of the relative angular distribution of gamma quantium with 11 divide 16 MeV energy using experimental data of Ta, W, Cu, Mo and Ti targets with various radiating lengths thicknesses.

  9. Systematical Analysis on Angular Distribution of Bremsstrahlung Radiation

    NASA Astrophysics Data System (ADS)

    Otgooloi, B.; Enkhbat, N.

    2009-03-01

    The systematic analysis has been made the measurement results of the relative angular distribution of gamma quantium with 11÷16 MeV energy using experimental data of Ta, W, Cu, Mo and Ti targets with various radiating lengths thicknesses.

  10. Technical Note: On Cerrobend shielding for 18-22 MeV electron beams

    SciTech Connect

    Wojcicka, Jadwiga B.; Yankelevich, Rafael; Werner, Barry Leonard; Lasher, Donette E.

    2008-10-15

    The purpose of this study is to investigate (1) the depth at which the measurement of the block transmission factor should be made, and (2) the level of the transmission of 18 and 22 MeV electron beams through conventional Cerrobend. We measured the block transmission in water phantom as ionization profiles across the beam and as ionization distributions along the central axis of the beam for 18 and 22 MeV electron beams, for cone sizes ranging from 6x10 cm{sup 2} to 25x25 cm{sup 2}. In our analysis, we separated the bremsstrahlung component produced in the Cerrobend block from the component originating in the head in the transmitted dose under the standard Cerrobend block. The block transmission for both beam energies and cone sizes was maximum on the central axis of the beam at depths between 0.4 and 0.7 cm. For the 18 MeV beam, the maximum transmission was 6.2% for the 6x10 cm{sup 2} cone, and 7.4% for the 25x25 cm{sup 2} cone. For the 22 MeV beam, it was 9.5% for the 6x10 cm{sup 2} cone, and 11.3% for the 25x25 cm{sup 2} cone. For the 22 MeV beam and 15x15 cm{sup 2} cone, it takes 2.95 and 1.4 cm of Cerrobend to reduce the maximum block transmission to 5% and 10%, respectively. The maximum dose under a blocked electron beam occurs on the central axis closer to the surface than it does for the open beam, and the block transmission factor should be defined at this shallower depth. To decrease the block transmission factor to the level of 5% on the central axis, electron beams with energy 18 MeV and greater require additional shielding.

  11. Studies of polarization bremsstrahlung and ordinary bremsstrahlung from 89Sr beta particles in metallic targets in the photon energy region of 1-100 keV

    NASA Astrophysics Data System (ADS)

    Singh, Amrit; Dhaliwal, A. S.

    2015-06-01

    Studies of polarization bremsstrahlung (PB) and ordinary bremsstrahlung (OB) produced by the 89Sr beta emitter in Al, Ti, Sn and Pb targets were undertaken at photon energies of 1-100 keV. The experimental results are compared with the Elwert corrected (non-relativistic) Bethe-Heitler (EBH) theory and the modified Elwert factor (relativistic) Bethe-Heitler (Fmod BH) theory for OB and with the Avdonina and Pratt (Fmod BH + PB) theory for total bremsstrahlung (BS). These results are in agreement with the Fmod BH + PB theory up to 13 keV, 16 keV, 22 keV and 28 keV energies for Al, Ti, Sn and Pb targets, respectively; Fmod BH theory is more accurate at higher energies.

  12. Effects of internal bremsstrahlung of tritium β-decay and surface roughness in the BIXS method

    NASA Astrophysics Data System (ADS)

    Mao, L.; An, Z.; Liang, J. H.; Long, X. G.; Peng, S. M.; Zhang, W. G.

    2011-01-01

    We have studied the effects of the internal bremsstrahlung of tritium β-decay, sample surface roughness and tritium content as well on the tritium β-decay induced X-ray spectroscopy (BIXS) for tritium measurements based on Monte Carlo simulations. The Knipp-Uhlenbeck-Bloch theoretical model was adopted for the internal bremsstrahlung. It is found that the contributions of internal bremsstrahlung of tritium β-decays are approximately 30%, 10%, 4% and 2% of the corresponding external bremsstrahlung for C, Ti, Mo and W materials, respectively, and the sample surface roughness may cause an error of several percent in the BIXS method if the surface roughness of a sample is in a reasonable range. Moreover, the effect of tritium content should be taken into account when a sample contains a large amount of tritium, otherwise, the tritium contents measured by the BIXS method will be underestimated, for example, by up to ˜15% for Ti metal.

  13. External bremsstrahlung spectra excited by 204Tl β particles in thick targets

    NASA Astrophysics Data System (ADS)

    Powar, M. S.; Ahmad, Salim; Singh, M.

    1980-06-01

    Spectral distributions of bremsstrahlung produced by 204Tl β particles in thick targets of Perspex, aluminum, copper, tin, and lead have been measured in a sandwich geometry. The contributions of internal bremsstrahlung produced along with the β particles have been determined by magnetic field deflection as well as the Z=O extrapolation method. Experimental results agree with Bethe-Heitler Born-approximation theory, corrected for Coulomb-field effects for low- and medium-Z targets, but show 25% positive deviation for high-Z targets. Again it is found that the bremsstrahlung produced in low-Z targets like Perspex is comparable with internal bremsstrahlung, and the corrections for its contribution to measurements by earlier workers can lead to large uncertainties.

  14. 10 CFR 50.70 - Inspections.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an...

  15. 10 CFR 50.70 - Inspections.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an...

  16. 10 CFR 50.70 - Inspections.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an...

  17. 10 CFR 50.70 - Inspections.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an...

  18. 10 CFR 50.70 - Inspections.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Director, Office of Nuclear Reactor Regulation or Director, Office of New Reactors, as appropriate, provide... New Reactors, or the Director, Office of Nuclear Reactor Regulation. All furniture, supplies and... construction permit holder (nuclear power reactor only) shall ensure that the arrival and presence of an...

  19. Proton-Proton Scattering at 105 Mev and 75 Mev

    DOE R&D Accomplishments Database

    Birge, R. W.; Kruse, U. E.; Ramsey, N. F.

    1951-01-31

    The scattering of protons by protons provides an important method for studying the nature of nuclear forces. Recent proton-proton scattering experiments at energies as high as thirty Mev{sup 1} have failed to show any appreciable contribution to the cross section from higher angular momentum states, but it is necessary to bring in tensor forces to explain the magnitude of the observed cross section.

  20. Gas bremsstrahlung shielding calculation for first optic enclosure of ILSF medical beamline

    NASA Astrophysics Data System (ADS)

    Beigzadeh Jalali, H.; Salimi, E.; Rahighi, J.

    2016-10-01

    Gas bremsstrahlung is generated in high energy electron storage ring accompanies the synchrotron radiation into the beamlines and strike the various components of the beamline. In this paper, radiation shielding calculation for secondary gas bremsstrahlung is performed for the first optics enclosure (FOE) of medical beamline of the Iranian Light Source Facility (ILSF). Dose equivalent rate (DER) calculation is accomplished using FLUKA Monte Carlo code. A comprehensive study of DER distribution at the back wall, sides and roof is given.

  1. Screening Effects on Nonrelativistic Bremsstrahlung in the Scattering of Electrons by Neutral Atoms

    NASA Technical Reports Server (NTRS)

    Jung, Young-Dae; Lee, Kun-Sang

    1995-01-01

    Atomic screening effects on nonrelativistic electron-atom bremsstrahlung radiation are investigated using a simple analytic solution of the Thomas-Fermi model for many-electron atoms. The Born approximation is assumed for the initial and final states of the projectile electron. The results show that the screening effect is important in the soft radiation region and is decreasing with increasing radiation. These results help provide correct information about the behavior of bound electrons in the target atom in bremsstrahlung processes.

  2. Optimizing the beam-beam alignment in an electron lens using bremsstrahlung

    SciTech Connect

    Montag, C.; Fischer, W.; Gassner, D.; Thieberger, P.; Haug, E.

    2010-05-23

    Installation of electron lenses for the purpose of head-on beam-beam compensation is foreseen at RHIC. To optimize the relative alignment of the electron lens beam with the circulating proton (or ion) beam, photon detectors will be installed to measure the bremsstrahlung generated by momentum transfer from protons to electrons. We present the detector layout and simulations of the bremsstrahlung signal as function of beam offset and crossing angle.

  3. A tuneable ultra-compact high-power, ultra-short pulsed, bright gamma-ray source based on bremsstrahlung radiation from laser-plasma accelerated electrons

    SciTech Connect

    Cipiccia, S.; Wiggins, S. M.; Shanks, R. P.; Islam, M. R.; Vieux, G.; Issac, R. C.; Brunetti, E.; Ersfeld, B.; Welsh, G. H.; Anania, M. P.; Jaroszynski, D. A.; Maneuski, D.; Shea, V. O.; Lemos, N. R. C.; Bendoyro, R. A.; Dias, J. M.; Bourgeois, N.; Ibbotson, T. P. A.; and others

    2012-03-15

    The laser driven plasma wakefield accelerator is a very compact source of high energy electrons. When the quasi-monoenergetic beam from these accelerators passes through dense material, high energy bremsstrahlung photons are emitted in a collimated beam with high flux. We show how a source based on this emission process can produce more than 10{sup 9} photons per pulse with a mean energy of 10 MeV. We present experimental results that show the feasibility of this method of producing high energy photons and compare the experimental results with GEANT4 Montecarlo simulations, which also give the scaling required to evaluate its suitability as method to produce radioisotopes via photo-nuclear reactions or for imaging applications.

  4. Resonant electron-atom bremsstrahlung in an intense laser field

    NASA Astrophysics Data System (ADS)

    Zheltukhin, A. N.; Flegel, A. V.; Frolov, M. V.; Manakov, N. L.; Starace, Anthony F.

    2014-02-01

    We analyze a resonant mechanism for spontaneous laser-assisted electron bremsstrahlung (BrS) involving the resonant transition (via either laser-assisted electron-ion recombination or electron-atom attachment) into a laser-dressed intermediate quasibound state (corresponding, respectively, to either a field-free neutral atom or a negative-ion bound state) accompanied by ionization or detachment of this state by the laser field. This mechanism leads to resonant enhancement (by orders of magnitude) of the BrS spectral density for emitted photon energies corresponding to those for laser-assisted recombination or attachment. We present an accurate parametrization of the resonant BrS amplitude in terms of the amplitudes for nonresonant BrS, for recombination or attachment to the intermediate state, and for ionization or detachment of this state. The high accuracy of our general analytic parametrization of the resonant BrS cross section is shown by comparison with exact numerical results for laser-assisted BrS spectra obtained within time-dependent effective range theory. Numerical estimates of resonant BrS in electron scattering from a Coulomb potential are also presented.

  5. Polarization of thermal bremsstrahlung emission due to electron pressure anisotropy

    NASA Astrophysics Data System (ADS)

    Komarov, S. V.; Khabibullin, I. I.; Churazov, E. M.; Schekochihin, A. A.

    2016-09-01

    Astrophysical plasmas are typically magnetized, with the Larmor radii of the charged particles many orders of magnitude smaller than their collisional mean free paths. The fundamental properties of such plasmas, e.g. conduction and viscosity, may depend on the instabilities driven by the anisotropy of the particle distribution functions and operating at scales comparable to the Larmor scales. We discuss a possibility that the pressure anisotropy of thermal electrons could produce polarization of thermal bremsstrahlung emission. In particular, we consider coherent large-scale motions in galaxy clusters to estimate the level of anisotropy driven by stretching of the magnetic-field lines by plasma flow and by heat fluxes associated with thermal gradients. Our estimate of the degree of polarization is ˜0.1 per cent at energies ≳kT. While this value is too low for the forthcoming generation of X-ray polarimeters, it is potentially an important proxy for the processes taking place at extremely small scales, which are impossible to resolve spatially. The absence of the effect at the predicted level may set a lower limit on the electron collisionality in the ICM. At the same time, the small value of the effect implies that it does not preclude the use of clusters as (unpolarized) calibration sources for X-ray polarimeters at this level of accuracy.

  6. Calibration of bremsstrahlung prefogged Kodak RAR 2492 film

    NASA Astrophysics Data System (ADS)

    Gorzen, D. F.; Armentrout, C.; Burek, A.; Bird, R.; Geddes, J.; Gerber, G.; Rockett, P. D.

    1990-10-01

    High-energy background radiation from PBFA II at Sandia National Laboratory introduces uncertainty regarding the effect of background fogging on the sensitivity of the x-ray film at soft x-ray energies. We have performed a calibration to determine how the sensitivity of the Kodak RAR 2492 film is affected by high-energy background radiation. To simulate the background radiation the film was fogged to various densities using a 10 keV bremsstrahlung spectrum. The film was then exposed to soft x-ray emission lines of Al Kα and Ti Kα selected by Bragg reflection from an electron bombardment source. The intensity of the x-ray flux was continuously monitored with a Si(Li) detector to eliminate error due to drift of the x-ray source's intensity. A microdensitometer with matched objectives was used to find the specular density of the exposed film. The results of the calibration are presented in the form of D vs log l for the various densities of the bremmstrahlung prefog exposures.

  7. A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

    NASA Astrophysics Data System (ADS)

    Döpp, A.; Guillaume, E.; Thaury, C.; Lifschitz, A.; Sylla, F.; Goddet, J.-P.; Tafzi, A.; Iaquanello, G.; Lefrou, T.; Rousseau, P.; Conejero, E.; Ruiz, C.; Ta Phuoc, K.; Malka, V.

    2016-09-01

    Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance with GEANT4 Monte-Carlo simulations, we measure a γ-ray source size of less than 100 μm for a 0.5 mm tantalum converter placed at 2 mm from the accelerator exit. Furthermore we present radiographs of image quality indicators.

  8. Influence of the electron-exchange and quantum shielding on the bremsstrahlung spectrum in degenerate quantum plasmas

    SciTech Connect

    Jung, Young-Dae

    2013-10-15

    The influence of the electron-exchange and quantum shielding on the bremsstrahlung spectrum is investigated in degenerate quantum plasmas. The impact-parameter analysis with the Shukla-Eliasson potential is applied to obtain the electron-ion bremsstrahlung radiation cross section as a function of the impact parameter, photon energy, projectile energy, electron-exchange parameter, Fermi energy, and plasmon energy. The result shows that the electron-exchange effect strongly enhances the bremsstrahlung radiation spectrum in degenerate quantum plasmas. It is also shown that the influence of the electron-exchange broadens the photon emission range in the electron-ion bremsstrahlung process. It is found that the electron-exchange effect focuses the bremsstrahlung photon energy in the soft photon domain. In addition, it is found that the bremsstrahlung radiation cross section increases with an increase of the Fermi energy and, however, decreases with increasing plasmon energy.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  10. Photonuclear reaction based high-energy x-ray spectrometer to cover from 2 MeV to 20 MeV

    SciTech Connect

    Sakata, S. Arikawa, Y.; Kojima, S.; Ikenouchi, T.; Nagai, T.; Abe, Y.; Inoue, H.; Morace, A.; Utsugi, M.; Nishimura, H.; Nakai, M.; Shiraga, H.; Fujioka, S.; Azechi, H.; Kato, R.

    2014-11-15

    A photonuclear-reaction-based hard x-ray spectrometer is developed to measure the number and energy spectrum of fast electrons generated by interactions between plasma and intense laser light. In this spectrometer, x-rays are converted to neutrons through photonuclear reactions, and the neutrons are counted with a bubble detector that is insensitive to x-rays. The spectrometer consists of a bundle of hard x-ray detectors that respond to different photon-energy ranges. Proof-of-principle experiment was performed on a linear accelerator facility. A quasi-monoenergetic electron bunch (N{sub e} = 1.0 × 10{sup −6} C, E{sub e} = 16 ± 0.32 MeV) was injected into a 5-mm-thick lead plate. Bremsstrahlung x-rays, which emanate from the lead plate, were measured with the spectrometer. The measured spectral shape and intensity agree fairly well with those computed with a Monte Carlo simulation code. The result shows that high-energy x-rays can be measured absolutely with a photon-counting accuracy of 50%–70% in the energy range from 2 MeV to 20 MeV with a spectral resolution (Δhν/hν) of about 15%. Quantum efficiency of this spectrometer was designed to be 10{sup −7}, 10{sup −4}, 10{sup −5}, respectively, for 2–10, 11–15, and 15–25 MeV of photon energy ranges.

  11. Optimization of a photoneutron source based on 10 MeV electron beam using Geant4 Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Askri, Boubaker

    2015-10-01

    Geant4 Monte Carlo code has been used to conceive and optimize a simple and compact neutron source based on a 10 MeV electron beam impinging on a tungsten target adjoined to a beryllium target. For this purpose, a precise photonuclear reaction cross-section model issued from the International Atomic Energy Agency (IAEA) database was linked to Geant4 to accurately simulate the interaction of low energy bremsstrahlung photons with beryllium material. A benchmark test showed that a good agreement was achieved when comparing the emitted neutron flux spectra predicted by Geant4 and Fluka codes for a beryllium cylinder bombarded with a 5 MeV photon beam. The source optimization was achieved through a two stage Monte Carlo simulation. In the first stage, the distributions of the seven phase space coordinates of the bremsstrahlung photons at the boundaries of the tungsten target were determined. In the second stage events corresponding to photons emitted according to these distributions were tracked. A neutron yield of 4.8 × 1010 neutrons/mA/s was obtained at 20 cm from the beryllium target. A thermal neutron yield of 1.5 × 109 neutrons/mA/s was obtained after introducing a spherical shell of polyethylene as a neutron moderator.

  12. X-Ray Radar Imaging Technique Using a 2 Mev Linear Electron Accelerator

    NASA Astrophysics Data System (ADS)

    Dreesen, W.; Schwellenbach, D.; Wood, J. R.; Browder, M.; Kallas, N.; Potter, J.

    X-ray radar imaging combines standard radar techniques with the penetration power of X-rays to image scenes. Our project strives to demonstrate the technique using a 2-MeV linear electron accelerator to generate the S-band--modulated X-ray signals. X-ray detectors such as photodiodes and scintillators are used to detect the signals in backscatter and transmission detection schemes. The S-band microstructure is imposed on the variable width electron pulse and this modulation carries over to the bremsstrahlung X-rays after the electron beam is incident upon a copper-tungsten alloy target. Using phase/distance calculations and a low-jitter system, we expect to detect different object distances by comparing the measured phase differences. The experimental setup, which meets strict jitter requirements, and preliminary experimental results are presented.

  13. Z-dependence of thick-target bremsstrahlung produced by monoenergetic low-energy electrons

    NASA Astrophysics Data System (ADS)

    Czarnecki, S.; Short, A.; Williams, S.

    2016-07-01

    The dependence of thick-target bremsstrahlung emitted by low-energy beams of monoenergetic electrons on the atomic number of the target material has been investigated experimentally for incident electron energies of 4.25 keV and 5.00 keV using thick aluminum, copper, silver, tungsten, and gold targets. Experimental data suggest that the intensity of the thick-target bremsstrahlung emitted is more strongly dependent on the atomic number of the target material for photons with energies that are approximately equal to the energy of the incident electrons than at lower energies, and also that the dependence of thick-target bremsstrahlung on the atomic number of the target material is stronger for incident electrons of higher energies than for incident electrons of lower energies. The results of the experiments are compared to the results of simulations performed using the PENELOPE program (which is commonly used in medical physics) and to thin-target bremsstrahlung theory, as well. Comparisons suggest that the experimental dependence of thick-target bremsstrahlung on the atomic number of the target material may be slightly stronger than the results of the PENELOPE code suggest.

  14. High power bremsstrahlung X-ray source for radiation processing

    NASA Astrophysics Data System (ADS)

    Yotsumoto, K.; Sunaga, H.; Tanaka, S.; Kanazawa, T.; Agematsu, T.; Tanaka, R.; Yoshida, K.; Taniguchi, S.; Sakamoto, I.; Tamura, N.

    The high power X-ray irradiation facility designed for the sterilization of medical appliances is described. The X-ray source consists of the 5 MeV, 300 kW Cockcroft Walton type of electron accelerator and the water cooled tantalum target. Conditions necessary for designing the X-ray target are conversion efficiency from electron beam to X-ray, thermal conductivity, readiness for machining and cost of the material. The conversion efficiency was determined through the Monte Carlo type calculation and obtained as 10.8 % for 3.667 g/cm 2 thickness (1 csda range) of tantalum target. In order to obtain the data on the source design, experiments have been carried out at the JAERI TAKASAKI 2 MeV, 60 kW Cockcroft-Walton type of electron accelerator equipped with a tantalum target. The size of package and the speed of conveyor was determined through the calculation of the absorbed dose distribution in the irradiated medium and the utilization efficiency.

  15. Anomalous inverse bremsstrahlung heating of laser-driven plasmas

    NASA Astrophysics Data System (ADS)

    Kundu, Mrityunjay

    2016-05-01

    Absorption of laser light in plasma via electron-ion collision (inverse bremsstrahlung) is known to decrease with the laser intensity as I 0 -3/2 or with the electron temperature as T e -3/2 where Coulomb logarithm ln Λ = 0.5ln(1 + k 2 min/k 2 max) in the expression of electron-ion collision frequency v ei is assumed to be independent of ponderomotive velocity v 0 = E0/ω which is unjustified. Here k -1 min = v th/max(ω, ω p), and k -1 max = Z/v 2 th are maximum and minimum cut-off distances of the colliding electron from the ion, v th = √T e is its thermal velocity, ω, ω p are laser and plasma frequency. Earlier with a total velocity v = (v 2 0 + v 2 th)1/2 dependent ln Λ(v) it was reported that v ei and corresponding fractional laser absorption (α) initially increases with increasing intensity, reaches a maximum value, and then fall according to the conventional I 0 -3/2 scaling. This anomalous increase in v ei and α may be objected due to an artifact introduced in ln Λ(v) through k-1 min ∝ v. Here we show similar anomalous increase of v ei and α versus I 0 (in the low temperature and under-dense density regime) with quantum and classical kinetic models of v ei without using ln Λ, but a proper choice of the total velocity dependent inverse cut-off length kmax -1 ∝ v 2 (in classical case) or kmax ∝ v (in quantum case). For a given I 0 < 5 × 1014Wcm-2, v ei versus T e also exhibits so far unnoticed identical anomalous increase as v ei versus Io, even if the conventional k max ∝ v2 th, or k max ∝ v th is chosen. However, for higher T e > 15 eV, anomalous growth of vei and a disappear. The total velocity dependent k max in kinetic models, as proposed here, may explain anomalous increase of a with I 0 measured in some earlier laser-plasma experiments. This work may be important to understand collisional absorption in the under-dense pre-plasma region due to low intensity pre-pulses and amplified spontaneous emission (ASE) pedestal in the

  16. LPM Interference and Cherenkov-like Gluon Bremsstrahlung in DenseMatter

    SciTech Connect

    Majumder, Abhijit; Wang, Xin-Nian

    2005-07-26

    Gluon bremsstrahlung induced by multiple parton scattering in a finite dense medium has a unique angular distribution with respect to the initial parton direction. A dead-cone structure with an opening angle; theta2{sub 0}; approx 2(1-z)/(zLE) for gluons with fractional energy z arises from the Landau-Pomeran chuck-Migdal (LPM) interference. In a medium where the gluon's dielectric constant is; epsilon>1, the LPM interference pattern is shown to become Cherenkov-like with an increased opening angle determined by the dielectric constant$/cos2/theta{sub c}=z+(1-z)//epsilon$. For a large dielectric constant/epsilon; gg 1+2/z2LE, the corresponding total radiative parton energy loss is about twice that from normal gluon bremsstrahlung. Implications of this Cherenkov-like gluon bremsstrahlung to the jet correlation pattern in high-energy heavy-ion collisions is discussed.

  17. Evaluation of bremsstrahlung contribution to photon transport in coupled photon-electron problems

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    The most accurate description of the radiation field in x-ray spectrometry requires the modeling of coupled photon-electron transport. Compton scattering and the photoelectric effect actually produce electrons as secondary particles which contribute to the photon field through conversion mechanisms like bremsstrahlung (which produces a continuous photon energy spectrum) and inner-shell impact ionization (ISII) (which gives characteristic lines). The solution of the coupled problem is time consuming because the electrons interact continuously and therefore, the number of electron collisions to be considered is always very high. This complex problem is frequently simplified by neglecting the contributions of the secondary electrons. Recent works (Fernández et al., 2013; Fernández et al., 2014) have shown the possibility to include a separately computed coupled photon-electron contribution like ISII in a photon calculation for improving such a crude approximation while preserving the speed of the pure photon transport model. By means of a similar approach and the Monte Carlo code PENELOPE (coupled photon-electron Monte Carlo), the bremsstrahlung contribution is characterized in this work. The angular distribution of the photons due to bremsstrahlung can be safely considered as isotropic, with the point of emission located at the same place of the photon collision. A new photon kernel describing the bremsstrahlung contribution is introduced: it can be included in photon transport codes (deterministic or Monte Carlo) with a minimal effort. A data library to describe the energy dependence of the bremsstrahlung emission has been generated for all elements Z=1-92 in the energy range 1-150 keV. The bremsstrahlung energy distribution for an arbitrary energy is obtained by interpolating in the database. A comparison between a PENELOPE direct simulation and the interpolated distribution using the data base shows an almost perfect agreement. The use of the data base increases

  18. Bremsstrahlung radiation from slow electrons in a Coulomb field: Classical limit and quantum correction

    SciTech Connect

    Manakov, N. L. Krylovetsky, A. A.; Marmo, S. I.

    2015-11-15

    Compact analytic expressions have been derived by a direct expansion in ħ → 0 for the nonrelativistic amplitude of Coulomb bremsstrahlung radiation (BR), the differential (in frequency and angles of the scattered electron) BR cross section, and the triply differential BR cross section that takes into account the bremsstrahlung photon direction and polarization and the scattered electron direction. They contain the classical limit and a quantum correction of the order of ħ at an arbitrary BR frequency ω. An explicit expression has been found for the quantum correction of the order of ħ to the classical BR spectrum.

  19. Bremsstrahlung and pair creation: Suppression mechanisms and how they affect EHE air showers

    SciTech Connect

    Klein, S.R.

    1997-12-01

    Most calculations of air shower development have been based on the Bethe-Heitler cross sections for bremsstrahlung and pair production. However, for energetic enough particles, a number of different external factors can reduce these cross sections drastically, slowing shower development and lengthening the showers. Four mechanisms that can suppress bremsstrahlung and pair production cross sections are discussed, and their effect on extremely high energy air showers considered. Besides lengthening the showers, these mechanisms greatly increase the importance of fluctuations in shower development, and can increase the angular spreading of showers.

  20. Quantum diffraction and shielding effects on the low-energy electron-ion bremsstrahlung in two-component semiclassical plasmas

    SciTech Connect

    Lee, Myoung-Jae; Jung, Young-Dae

    2015-10-15

    The quantum diffraction and shielding effects on the low-energy bremsstrahlung process are investigated in two-component semiclassical plasmas. The impact-parameter analysis with the micropotential taking into account the quantum diffraction and shielding effects is employed to obtain the electron-ion bremsstrahlung radiation cross section as a function of the de Broglie wavelength, density parameter, impact parameter, photon energy, and projectile energy. The result shows that the influence of quantum diffraction and shielding strongly suppresses the bremsstrahlung radiation spectrum in semiclassical plasmas. It is found that the quantum diffraction and shielding effects have broaden the photon emission domain. It is also found that the photon emission domain is almost independent of the radiation photon energy. In addition, it is found that the influence of quantum diffraction and shielding on the bremsstrahlung spectrum decreases with an increase of the projectile energy. The density effect on the electron-ion bremsstrahlung cross section is also discussed.

  1. Modeling of the electron distribution based on bremsstrahlung emission during lower hybrid current drive on PLT

    SciTech Connect

    Stevens, J.E.; von Goeler, S.; Bernabei, S.; Bitter, M.; Chu, T.K.; Efthimion, P.; Fisch, N.; Hooke, W.; Hosea, J.; Jobes, F.

    1985-03-01

    Lower hybrid current drive requires the generation of a high energy electron tail anisotropic in velocity. Measurements of bremsstrahlung emission produced by this tail are compared with the calculated emission from reasonable model distributions. The physical basis and the sensitivity of this modeling process are described and the plasma properties of current driven discharges which can be derived from the model are discussed.

  2. The Gluckstern-Hull formula for electron-nucleus bremsstrahlung. Technical report

    SciTech Connect

    Brandt, H.E.

    1980-05-01

    The Gluckstern-Hull formula for the electron-nucleus bremsstrahlung cross section, containing the emitted photon angular dependence with the recoil electron angular dependence integrated out, is shown to be correct. This formula is required to calculate continuum x-ray spectra radiated from anisotropic relativistic beam-plasma systems.

  3. 10 MeV Electron Beam Test Using Gas Electron Multiplier (GEM) Detectors

    NASA Astrophysics Data System (ADS)

    Hahn, C. H.; Kim, I. G.; Park, S. T.; Kim, W. J.; Yoo, D. S.; Moon, B. S.; Ha, S. Y.; Ahn, B. J.; Ha, Y. J.; Jung, C. Y.; Jung, S. H.; Cho, B. H.; Lee, B. C.; Han, Y. H.; Chung, C. E.; Li, J.; White, A. P.; Yu, J.

    2006-10-01

    10 MeV electron beam has been tested using a single channel double gas electron multiplier (GEM) detector constructed by Changwon National University and a multi-channel double GEM chamber by the University of Texas at Arlington. It has been demonstrated that both detectors are able to detect signals generated by high energy electrons as well as x-rays. By analyzing the chamber output signals captured by oscilloscope, it is believed that the x-ray was produced by bremsstrahlung while electrons were decelerating in a 2 mm lead plate. The time profile of the KAERI's 10 MeV electron beam bunches was determined based on the calculated angular distribution of electrons by multiple scattering in the lead plate. Furthermore, the spatial electron density distribution has been extrapolated by using the time profile. The effective gain of the GEM chamber has been estimated by analyzing the measured output currents of the chamber. It is important that the time and spatial profiles of the high energy electron beam could be determined using GEM detectors, which suggests that GEM might have an application as a calorimeter for a large scale accelerator. Details of experimental procedure will be discussed.

  4. Collimator and energy window optimization for ⁹⁰Y bremsstrahlung SPECT imaging: A SIMIND Monte Carlo study.

    PubMed

    Roshan, Hoda Rezaei; Mahmoudian, Babak; Gharepapagh, Esmaeil; Azarm, Ahmadreza; Islamian, Jalil Pirayesh

    2016-02-01

    Treatment efficacy of radioembolization using Yttrium-90 ((90)Y) microspheres is assessed by the (90)Y bremsstrahlung single photon emission computed tomography (SPECT) imaging following radioembolization. The radioisotopic image has the potential of providing reliable activity map of (90)Y microspheres distribution. One of the main reasons of the poor image quality in (90)Y bremsstrahlung SPECT imaging is the continuous and broad energy spectrum of the related bremsstrahlung photons. Furthermore, collimator geometry plays an impressive role in the spatial resolution, sensitivity and image contrast. Due to the relatively poor quality of the (90)Y bremsstrahlung SPECT images, we intend to optimize the medium-energy (ME) parallel-hole collimator and energy window. The Siemens e.cam gamma camera equipped with a ME collimator and a voxelized phantom was simulated by the SImulating Medical Imaging Nuclear Detectors (SIMIND) program. We used the SIMIND Monte Carlo program to generate the (90)Y bremsstrahlung SPECT projection of the digital Jaszczak phantom. The phantom consist of the six hot spheres ranging from 9.5 to 31.8mm in diameter, which are used to evaluate the image contrast. In order to assess the effect of the energy window on the image contrast, three energy windows ranging from 60 to 160 KeV, 160 to 400 KeV, and 60 to 400 KeV were set on a (90)Y bremsstrahlung spectrum. As well, the effect of the hole diameter of a ME collimator on the image contrast and bremsstrahlung spectrum were investigated. For the fixed collimator and septa thickness values (3.28 cm and 1.14 mm, respectively), a hole diameter range (2.35-3.3mm) was chosen based on the appropriate balance between the spatial resolution and sensitivity. The optimal energy window for (90)Y bremsstrahlung SPECT imaging was extended energy window from 60 to 400 KeV. Besides, The optimal value of the hole diameter of ME collimator was obtained 3.3mm. Geometry of the ME parallel-hole collimator and energy

  5. Characterization of γ-ray detectors using the photon tagger NEPTUN for energies up to 20 MeV

    NASA Astrophysics Data System (ADS)

    Schnorrenberger, L.; Savran, D.; Glorius, J.; Lindenberg, K.; Löher, B.; Pietralla, N.; Sonnabend, K.

    2014-01-01

    A new setup for the characterization of γ-ray detectors has been installed at the NEPTUN photon tagger facility of TU Darmstadt. The tagging technique used at NEPTUN provides a quasi monoenergetic photon source up to about 20 MeV by selecting single γ-ray energies within a bremsstrahlung spectrum. The energy is freely selectable by changing the tagging condition. The detector response function (DRF) of γ-ray detectors for quasi monoenergetic incident photons can be measured. This allows to investigate DRFs of various photon detectors as a function of the incident γ-ray energy. Simulations of DRFs that are intensively used in the analysis of nuclear physics experiments can be tested and compared to experimental data. The experimental setup is presented and the measurement of the DRF of a large volume high-purity Germanium detector is described as an example.

  6. Photon bremsstrahlung from quark jet via transverse and longitudinal scattering: Single versus multiple scattering

    NASA Astrophysics Data System (ADS)

    Zhang, Le; Hou, De-Fu; Qin, Guang-You

    2016-08-01

    We study the production of jet-bremsstrahlung photons through scattering with the constituents of dense nuclear matter within the framework of deep-inelastic scattering off a large nucleus. Applying a gradient expansion up to the second order for the exchanged three-dimensional momentum between jet and medium, we derive the single-photon bremsstrahlung spectrum with the inclusion of contributions from the transverse broadening as well as the longitudinal drag and diffusion of the hard parton's momentum. We also compare the medium-induced photon radiation spectra for single scattering and from the resummation of multiple scatterings. It is found that the coupling between different scatterings can give an additional contribution to medium-induced photon radiation, while for small momentum exchange the leading contribution from the drag and diffusions to the photon emission spectra remain the same for single and multiple scatterings.

  7. An Investigation of Bremsstrahlung Reflection in a Dense Plasma Focus (DPF) Propulsion Device

    SciTech Connect

    Thomas, Robert; Miley, G. H.; Mead, Franklin

    2006-01-20

    The dense plasma focus device is one of the few fusion systems that is capable of burning advanced fuels such as D - 3He and p - 11B. An study has been performed and shown that three main requirements must be satisfied to reach breakeven for DPF fusion: a high Ti/Te ration ({approx} 20), an order of magnitude higher pinch lifetime, and the reflection and absorption if at least 50% Bremsstrahlung radiation. The latter issue is the focus of this report, and a literature search has been performed on laser-driven fusion radiation cavities, multilayer reflectors, and their application to Bremsstrahlung radiation reflection is presented. Additionally, the results found are compared to those assumed in the earlier DPF study bring p-11B.

  8. Measurements of bremsstrahlung production and x-ray cryostat heating in VENUS

    SciTech Connect

    Lyneis, C.; Leitner, D.; Todd, D.; Virostek, S.; Loew, T.; Heinen, A.; Tarvainen, O.

    2006-03-15

    The VENUS superconducting electron cyclotron resonance (ECR) ion source is designed to operate at 28 GHz with up to 10 kW of rf power. Most of this power is absorbed by the plasma electrons and then dumped onto the plasma chamber wall. The distribution of heating and bremsstrahlung production is highly nonuniform and reflects the geometry of the magnetic confinement fields. The nonuniform distribution of electron losses to the wall results in localized heating on the aluminum chamber walls, which can lead to burnout. In addition, part of the bremsstrahlung produced by the collision of the hot-electrons with the walls is absorbed by the cold mass of the superconducting magnet leading to an additional heat load in the cryostat in the order of several watts. Therefore a new plasma chamber has been installed that incorporates a high-Z tantalum shield to reduce the cryostat heating and enhance water cooling to minimize the chance of burnout. In order to better understand the heat load, the spectrum of the bremsstrahlung has been carefully measured as a function of rf power, magnetic confinement, and rf frequency. In addition, the distribution of electron heating in VENUS magnetic field has been simulated with a three-dimensional computer code [H. Heinen and H. J. Andra, Proceedings of the 14th International Workshop on ECR Sources (CERN, Geneva, 1999), 224; H. J. Andra and A. Heinen, Proceedings of the 15th International Workshop on ECR lon Sources, ECRIS'02 (Jyvaeskylae, Finland 2002), 85.] to better understand the heat load distribution on the plasma chamber wall. The new plasma chamber design, results of the bremsstrahlung measurements, and the effectiveness of the high-Z shielding are described.

  9. Thermalisation and hard X-ray bremsstrahlung efficiency of self-interacting solar flare fast electrons

    NASA Astrophysics Data System (ADS)

    Galloway, R. K.; Helander, P.; MacKinnon, A. L.; Brown, J. C.

    2010-09-01

    Context. Most theoretical descriptions of the production of solar flare bremsstrahlung radiation assume the collision of dilute accelerated particles with a cold, dense target plasma, neglecting interactions of the fast particles with each other. This is inadequate for situations where collisions with this background plasma are not completely dominant, as may be the case in, for example, low-density coronal sources. Aims: We aim to formulate a model of a self-interacting, entirely fast electron population in the absence of a dense background plasma, to investigate its implications for observed bremsstrahlung spectra and the flare energy budget. Methods: We derive approximate expressions for the time-dependent distribution function of the fast electrons using a Fokker-Planck approach. We use these expressions to generate synthetic bremsstrahlung X-ray spectra as would be seen from a corresponding coronal source. Results: We find that our model qualitatively reproduces the observed behaviour of some flares. As the flare progresses, the model's initial power-law spectrum is joined by a lower energy, thermal component. The power-law component diminishes, and the growing thermal component proceeds to dominate the total emission over timescales consistent with flare observations. The power-law exhibits progressive spectral hardening, as is seen in some flare coronal sources. We also find that our model requires a factor of 7-10 fewer accelerated electrons than the cold, thick target model to generate an equivalent hard X-ray flux. Conclusions: This model forms the basis of a treatment of self-interactions among flare fast electrons, a process which affords a more efficient means to produce bremsstrahlung photons and so may reduce the efficiency requirements placed on the particle acceleration mechanism. It also provides a useful description of the thermalisation of fast electrons in coronal sources.

  10. Investigation of Coulombic bremsstrahlung spectra of metallic targets for the photon energy region of 1-100keV.

    PubMed

    Singh, Amrit; Dhaliwal, A S

    2016-09-01

    In the present paper, the formation of bremsstrahlung spectra by ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB) in metallic targets by (35)S beta particles has been investigated in the photon energy region of 1-100keV. From the experimental measurements and the theoretical results obtained from Elwert corrected (non-relativistic) Bethe Heitler (EBH) theory, modified Elwert factor (relativistic) (FmodBH) theories for OB and Avdonina and Pratt (FmodBH+PB) theory for total bremsstrahlung (BS) having the contribution of PB into OB, it has been found that the contribution of PB into BS in a target is limited to a low energy region only and also varies with the atomic number of target material. The FmodBH+PB theory is in agreement with the experimental results in low energy regions of the target, whereas at high energy region FmodBH is found to give better agreement. Further, the present experimental results indicate that the screening effects in the Coulombic bremsstrahlung process cannot be neglected in the high energy region, and the multiple scattering and secondary electron emissions effects in thick target are required to be taken into account in describing the bremsstrahlung process. PMID:27400163

  11. Investigation of Coulombic bremsstrahlung spectra of metallic targets for the photon energy region of 1-100keV.

    PubMed

    Singh, Amrit; Dhaliwal, A S

    2016-09-01

    In the present paper, the formation of bremsstrahlung spectra by ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB) in metallic targets by (35)S beta particles has been investigated in the photon energy region of 1-100keV. From the experimental measurements and the theoretical results obtained from Elwert corrected (non-relativistic) Bethe Heitler (EBH) theory, modified Elwert factor (relativistic) (FmodBH) theories for OB and Avdonina and Pratt (FmodBH+PB) theory for total bremsstrahlung (BS) having the contribution of PB into OB, it has been found that the contribution of PB into BS in a target is limited to a low energy region only and also varies with the atomic number of target material. The FmodBH+PB theory is in agreement with the experimental results in low energy regions of the target, whereas at high energy region FmodBH is found to give better agreement. Further, the present experimental results indicate that the screening effects in the Coulombic bremsstrahlung process cannot be neglected in the high energy region, and the multiple scattering and secondary electron emissions effects in thick target are required to be taken into account in describing the bremsstrahlung process.

  12. Optimal Design of Anger Camera for Bremsstrahlung Imaging: Monte Carlo Evaluation

    PubMed Central

    Walrand, Stephan; Hesse, Michel; Wojcik, Randy; Lhommel, Renaud; Jamar, François

    2014-01-01

    A conventional Anger camera is not adapted to bremsstrahlung imaging and, as a result, even using a reduced energy acquisition window, geometric x-rays represent <15% of the recorded events. This increases noise, limits the contrast, and reduces the quantification accuracy. Monte Carlo (MC) simulations of energy spectra showed that a camera based on a 30-mm-thick BGO crystal and equipped with a high energy pinhole collimator is well-adapted to bremsstrahlung imaging. The total scatter contamination is reduced by a factor 10 versus a conventional NaI camera equipped with a high energy parallel hole collimator enabling acquisition using an extended energy window ranging from 50 to 350 keV. By using the recorded event energy in the reconstruction method, shorter acquisition time and reduced orbit range will be usable allowing the design of a simplified mobile gantry. This is more convenient for use in a busy catheterization room. After injecting a safe activity, a fast single photon emission computed tomography could be performed without moving the catheter tip in order to assess the liver dosimetry and estimate the additional safe activity that could still be injected. Further long running time MC simulations of realistic acquisitions will allow assessing the quantification capability of such system. Simultaneously, a dedicated bremsstrahlung prototype camera reusing PMT–BGO blocks coming from a retired PET system is currently under design for further evaluation. PMID:24982849

  13. High level tritiated water monitoring by Bremsstrahlung counting using a silicon drift detector

    SciTech Connect

    Niemes, S.; Sturm, M.; Michling, R.; Bornschein, B.

    2015-03-15

    The β-ray induced X-ray spectrometry (BIXS) is a promising technique to monitor the tritium concentration in a fuel cycle of a fusion reactor. For in-situ measurements of high level tritiated water by Bremsstrahlung counting, the characteristics of a low-noise silicon drift detector (SDD) have been examined at the Tritium Laboratory Karlsruhe (TLK). In static measurements with constant sample volume and tritium concentration, the Bremsstrahlung spectra of tritiated water samples in a concentration range of 0.02 to 15 MBq/ml have been obtained. The volume has been kept constant at 5 cm{sup 3}. The observed spectra are well above the noise threshold. In addition to X-rays induced by β-rays, the spectra feature X-ray fluorescence peaks of the surrounding materials. No indications of memory effects have been observed. A linear relation between the X-ray intensity and the tritium concentration was obtained and the lower detection limit of the setup has been determined to 1 MBq ml{sup -1}, assessed by the Curie criterion. In addition, the spectra obtained experimentally could be reproduced with high agreement by Monte-Carlo simulations using the GEANT4-tool-kit. It was found that the present detection system is applicable to non-invasive measurements of high-level tritiated water and the SDD is a convenient tool to detect the low energy Bremsstrahlung X-rays. (authors)

  14. Optimal design of anger camera for bremsstrahlung imaging: monte carlo evaluation.

    PubMed

    Walrand, Stephan; Hesse, Michel; Wojcik, Randy; Lhommel, Renaud; Jamar, François

    2014-01-01

    A conventional Anger camera is not adapted to bremsstrahlung imaging and, as a result, even using a reduced energy acquisition window, geometric x-rays represent <15% of the recorded events. This increases noise, limits the contrast, and reduces the quantification accuracy. Monte Carlo (MC) simulations of energy spectra showed that a camera based on a 30-mm-thick BGO crystal and equipped with a high energy pinhole collimator is well-adapted to bremsstrahlung imaging. The total scatter contamination is reduced by a factor 10 versus a conventional NaI camera equipped with a high energy parallel hole collimator enabling acquisition using an extended energy window ranging from 50 to 350 keV. By using the recorded event energy in the reconstruction method, shorter acquisition time and reduced orbit range will be usable allowing the design of a simplified mobile gantry. This is more convenient for use in a busy catheterization room. After injecting a safe activity, a fast single photon emission computed tomography could be performed without moving the catheter tip in order to assess the liver dosimetry and estimate the additional safe activity that could still be injected. Further long running time MC simulations of realistic acquisitions will allow assessing the quantification capability of such system. Simultaneously, a dedicated bremsstrahlung prototype camera reusing PMT-BGO blocks coming from a retired PET system is currently under design for further evaluation.

  15. Integrated Bayesian Estimation of Zeff in the TEXTOR Tokamak from Bremsstrahlung and CX Impurity Density Measurements

    NASA Astrophysics Data System (ADS)

    Verdoolaege, G.; Von Hellermann, M. G.; Jaspers, R.; Ichir, M. M.; Van Oost, G.

    2006-11-01

    The validation of diagnostic date from a nuclear fusion experiment is an important issue. The concept of an Integrated Data Analysis (IDA) allows the consistent estimation of plasma parameters from heterogeneous data sets. Here, the determination of the ion effective charge (Zeff) is considered. Several diagnostic methods exist for the determination of Zeff, but the results are in general not in agreement. In this work, the problem of Zeff estimation on the TEXTOR tokamak is approached from the perspective of IDA, in the framework of Bayesian probability theory. The ultimate goal is the estimation of a full Zeff profile that is consistent both with measured bremsstrahlung emissivities, as well as individual impurity spectral line intensities obtained from Charge Exchange Recombination Spectroscopy (CXRS). We present an overview of the various uncertainties that enter the calculation of a Zeff profile from bremsstrahlung date on the one hand, and line intensity data on the other hand. We discuss a simple linear and nonlinear Bayesian model permitting the estimation of a central value for Zeff and the electron density ne on TEXTOR from bremsstrahlung emissivity measurements in the visible, and carbon densities derived from CXRS. Both the central Zeff and ne are sampled using an MCMC algorithm. An outlook is given towards possible model improvements.

  16. A measurement of the magnetic dipole moment of the. delta. /sup + +/(1232) from the bremsstrahlung process. pi. p. -->. pi. p. gamma

    SciTech Connect

    Meyer, C.A.

    1987-06-01

    We have measured the cross section from the bremsstrahlung process ..pi../sup +/p ..-->.. ..pi../sup +/p..gamma.. for incident pions of energy 299 MeV. We detected the out going pion in the angular range from 55 to 95/sup 0/ in the lab, and photons were detected near 240/sup 0/ in the lab. We compare this measured cross-section to the MIT theory in order to extract a measurement of the magnetic dipole moment of the ..delta../sup + +/(1232), ..mu../sub ..delta../. In order to compare our results with the MIT theory, we have folded the MIT theory into the acceptance of our apparatus. We find that for pion angles between 55 and 75/sup 0/ the theory gives us a dipole moment of: 2.3..mu../sub p/ < ..mu../sub ..delta../ < 3.3..mu../sup p/ where the quoted error arises from an experimental uncertainty of +-0.25..mu../sub p/ and from theoretical uncertainties of +-0.25 ..mu../sub p/. However, for pion angles between 75 and 95/sup 0/ we find that the MIT theory predicts a cross-section which is larger than our measured cross-section, and makes it difficult to extract a value of ..mu../sub ..delta../. This over prediction is not understood, but consistent with a similar effect when the MIT theory is fit to previous data. 78 figs., 29 tabs.

  17. Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited)

    NASA Astrophysics Data System (ADS)

    Cooper, C. M.; Pace, D. C.; Paz-Soldan, C.; Commaux, N.; Eidietis, N. W.; Hollmann, E. M.; Shiraki, D.

    2016-11-01

    A new gamma ray imager (GRI) is developed to probe the electron distribution function with 2D spatial resolution during runaway electron (RE) experiments at the DIII-D tokamak. The diagnostic is sensitive to 0.5-100 MeV gamma rays, allowing characterization of the RE distribution function evolution during RE growth and dissipation. The GRI consists of a lead "pinhole camera" mounted on the DIII-D midplane with 123 honeycombed tangential chords 20 cm wide that span the vessel interior. Up to 30 bismuth germanate (BGO) scintillation detectors capture RE bremsstrahlung radiation for Pulse Height Analysis (PHA) capable of discriminating up to 20 000 pulses per second. Digital signal processing routines combining shaping filters are performed during PHA to reject noise and record gamma ray energy. The GRI setup and PHA algorithms will be described and initial data from experiments will be presented. A synthetic diagnostic is developed to generate the gamma ray spectrum of a GRI channel given the plasma information and a prescribed distribution function. Magnetic reconstructions of the plasma are used to calculate the angle between every GRI sightline and orient and discriminate gamma rays emitted by a field-aligned RE distribution function.

  18. Energy loss, range, and bremsstrahlung yield for 10-keV to 100-MeV electrons in various elements and chemical compounds

    NASA Astrophysics Data System (ADS)

    Pages, Lucien; Bertel, Evelyne; Joffre, Henri; Sklavenitis, Laodamas

    2012-12-01

    Even though the United States lacks a national climate policy, significant action has occurred at the local and regional levels. Some of the most aggressive climate change policies have occurred at the state and local levels and in interagency cooperation on specific management issues. While there is a long history of partnerships in dealing with a wide variety of policy issues, the uncertainty and the political debate surrounding climate change has generated new challenges to establishing effective policy networks. This paper investigates the formation of climate policy networks in the State of Nevada. It presents a methodology based on social network analysis for assessing the structure and function of local policy networks across a range of substantive climate impacted resources (water, landscape management, conservation, forestry and others). It draws from an emerging literature on federalism and climate policy, public sector innovation, and institutional analysis in socio-ecological systems. Comparisons across different policy issue networks in the state are used to highlight the influence of network structure, connectivity, bridging across vertical and horizontal organizational units, organizational diversity, and flows between organizational nodes.

  19. Dose assessment of bremsstrahlung induced by beta-emitting radioisotopes of uranium-238 series and lead in human tissues.

    PubMed

    Manjunatha, H C

    2014-01-01

    In the natural uranium-238 decay series, pure beta isotopes such as (234)Th, (234)Pa, (214)Pb, (214)Bi, (210)Pb and (210)Bi are released. The few lead isotopes such as (211)Pb, (212)Pb, (213)Pb and (215)Pb are good beta emitters. In certain nuclear reactions of reactor these isotopes are released. These beta isotopes have maximum beta energies, which induce the bremsstrahlung radiation. The bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. The shapes of bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. The bremsstrahlung spectra produced by these high-energy isotopes such as (234)Th, (234)Pa, (214)Pb, (214)Bi, (210)Pb, (210)Bi, (211)Pb, (212)Pb, (213)Pb and (215)Pb in bone, muscle and teeth are studied, and the computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth-dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The evaluated beta bremsstrahlung dose as a function distance for the studied nuclides is also presented. The efficiency, intensity and dose rate of bremsstrahlung induced by beta isotopes of natural uranium-238 decay series and beta-emitting lead isotopes in human tissues such as brain, breast, heart, kidney, liver, muscle, pancreas and bone have also been studied in the present investigation. The values of bremsstrahlung dosimetric parameters are low for pancreas, but they are high for bone. For all studied tissues these parameters are high for (234)Pa, but low for (210)Pb.

  20. Time evolution of endpoint energy of Bremsstrahlung spectra and ion production from an electron cyclotron resonance ion source

    SciTech Connect

    Tarvainen, Ollie; Ropponen, Tommi; Jones, Peter; Kalvas, Taneli

    2008-01-01

    Electron cyclotron resonance ion sources (ECRIS) are used to produce high charge state heavy ion beams for the use of nuclear and materials science, for instance. The most powerful ECR ion sources today are superconducting. One of the problems with superconducting ECR ion sources is the use of high radio frequency (RF) power which results in bremsstrahlung radiation adding an extra heat load to the cryostat. In order to understand the electron heating process and timescales in the ECR plasma, time evolution measurement of ECR bremsstrahlung was carried out. In the measurements JYFL 14 GHz ECRIS was operated in a pulsed mode and bremsstrahlung data from several hundred RF pulses was recorded. Time evolution of ion production was also studied and compared to one of the electron heating theories. To analyze the measurement data at C++ program was developed. Endpoint energies of the bremsstrahlung spectra as a function of axial magnetic field strength, pressure and RF power are presented and ion production timescales obtained from the measurements are compared to bremsstrahlung emission timescales and one of the stochastic heating theories.

  1. The stonehenge technique: a new method of crystal alignment for coherent bremsstrahlung experiments

    NASA Astrophysics Data System (ADS)

    Livingston, Kenneth

    2005-08-01

    In the coherent bremsstrahlung technique a thin diamond crystal oriented correctly in an electron beam can produce photons with a high degree of linear polarization.1 The crystal is mounted on a goniometer to control its orientation and it is necessary to measure the angular offsets a) between the crystal axes and the goniometer axes and b) between the goniometer and the electron beam axis. A method for measuring these offsets and aligning the crystal was developed by Lohman et al, and has been used successfully in Mainz.2 However, recent attempts to investigate new crystals have shown that this approach has limitations which become more serious at higher beam energies where more accurate setting of the crystal angles, which scale with l/Ebeam, is required. (Eg. the recent installation of coherent bremsstrahlung facility at Jlab, with Ebeam = 6 GeV ) This paper describes a new, more general alignment technique, which overcomes these limitations. The technique is based on scans where the horizontal and vertical rotation axes of the goniometer are adjusted in a series of steps to make the normal to the crystal describe a cone of a given angle. For each step in the scan, the photon energy spectrum is measured using a tagging spectrometer, and the offsets between the electron beam and the crystal lattice are inferred from the resulting 2D plot. Using this method, it is possible to align the crystal with the beam quickly, and hence to set any desired orientation of the crystal relative to the beam. This is essential for any experiment requiring linearly polarized photons produced via coherent bremsstrahlung, and is also required for a systematic study of the channeling radiation produced by the electron beam incident on the crystal.

  2. Coincidence measurement of the fully differential cross section for atomic-field bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Faulk, J. D.; Quarles, C. A.

    1974-01-01

    A coincidence measurement was made of the absolute cross section for electron-atomic-field bremsstrahlung, differential in photon energy, photon-emission angle, and electron scattering angle. The incident electron energy was 140 keV and the scattering materials were thin films of aluminum and gold. The data are compared to the theoretical calculations of Elwert and Haug and of Bethe and Heitler. Both theories give generally satisfactory agreement for aluminum. The Elwert-Haug theory is somewhat more accurate for gold.

  3. Angular distribution of the bremsstrahlung emission during lower-hybrid current drive on PLT

    SciTech Connect

    von Goeler, S.; Stevens, J.; Bernabei, S.; Bitter, M.; Chu, T.K.; Efthimion, P.; Fisch, N.; Hooke, W.; Hill, K.; Hosea, J.

    1985-06-01

    The bremsstrahlung emission from the PLT tokamak during lower-hybrid current drive has been measured as a function of angle between the magnetic field and the emission direction. The emission is peaked strongly in the forward direction, indicating a strong anisotropy of the electron-velocity distribution. The data demonstrate the existence of a nearly flat tail of the velocity distribution, which extends out to approximately 500 keV and which is interpreted as the plateau created by Landau damping of the lower-hybrid waves.

  4. Non-Abelian Bremsstrahlung and Azimuthal Asymmetries in High Energy p+A Reactions

    SciTech Connect

    Gyulassy, Miklos; Vitev, Ivan Mateev; Levai, Peter; Biro, Tamas S.

    2014-09-25

    Here we apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute the all-order in nuclear opacity non-abelian gluon bremsstrahlung of event- by-event uctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, v$M\\atop{n}$ {1}, and even number 2ℓ gluon, v$M\\atop{n}$ {2ℓ} inclusive distributions in high energy p+A reactions as a function of harmonic $n$, target recoil cluster number, $M$, and gluon number, 2ℓ, at RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form Color Scintillation Antenna (CSA) arrays that lead to character- istic boost non-invariant trapezoidal rapidity distributions in asymmetric B+A nuclear collisions. The scaling of intrinsically azimuthally anisotropic and long range in η nature of the non-Abelian bremsstrahlung leads to vn moments that are similar to results from hydrodynamic models, but due entirely to non-Abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic non-flow solutions are similar to recent numerical saturation model predictions but differ by predicting a simple power-law hierarchy of both even and odd vn without invoking kT factorization. A test of CSA mechanism is the predicted nearly linear η rapidity dependence of the vn(kTη). Non- Abelian beam jet bremsstrahlung may thus provide a simple analytic solution to Beam Energy Scan (BES) puzzle of the near $\\sqrt{s}$ independence of vn(pT) moments observed down to 10 AGeV where large-x valence quark beam jets dominate inelastic dynamics. Recoil bremsstrahlung from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of vn in p(D) + A and non-central A + A at same dN=dη multiplicity as observed at RHIC and LHC.

  5. Non-Abelian Bremsstrahlung and Azimuthal Asymmetries in High Energy p+A Reactions

    DOE PAGESBeta

    Gyulassy, Miklos; Vitev, Ivan Mateev; Levai, Peter; Biro, Tamas S.

    2014-09-25

    Here we apply the GLV reaction operator solution to the Vitev-Gunion-Bertsch (VGB) boundary conditions to compute the all-order in nuclear opacity non-abelian gluon bremsstrahlung of event- by-event uctuating beam jets in nuclear collisions. We evaluate analytically azimuthal Fourier moments of single gluon, vmore » $$M\\atop{n}$$ {1}, and even number 2ℓ gluon, v$$M\\atop{n}$$ {2ℓ} inclusive distributions in high energy p+A reactions as a function of harmonic $n$, target recoil cluster number, $M$, and gluon number, 2ℓ, at RHIC and LHC. Multiple resolved clusters of recoiling target beam jets together with the projectile beam jet form Color Scintillation Antenna (CSA) arrays that lead to character- istic boost non-invariant trapezoidal rapidity distributions in asymmetric B+A nuclear collisions. The scaling of intrinsically azimuthally anisotropic and long range in η nature of the non-Abelian bremsstrahlung leads to vn moments that are similar to results from hydrodynamic models, but due entirely to non-Abelian wave interference phenomena sourced by the fluctuating CSA. Our analytic non-flow solutions are similar to recent numerical saturation model predictions but differ by predicting a simple power-law hierarchy of both even and odd vn without invoking kT factorization. A test of CSA mechanism is the predicted nearly linear η rapidity dependence of the vn(kTη). Non- Abelian beam jet bremsstrahlung may thus provide a simple analytic solution to Beam Energy Scan (BES) puzzle of the near $$\\sqrt{s}$$ independence of vn(pT) moments observed down to 10 AGeV where large-x valence quark beam jets dominate inelastic dynamics. Recoil bremsstrahlung from multiple independent CSA clusters could also provide a partial explanation for the unexpected similarity of vn in p(D) + A and non-central A + A at same dN=dη multiplicity as observed at RHIC and LHC.« less

  6. Effect of electron collisions on transport coefficients induced by the inverse bremsstrahlung absorption in plasmas

    SciTech Connect

    Bendib, A.; Tahraoui, A.; Bendib, K.; Mohammed El Hadj, K.; Hueller, S.

    2005-03-01

    The transport coefficients of fully ionized plasmas under the influence of a high-frequency electric field are derived solving numerically the electron Fokker-Planck equation using a perturbation method, parametrized as a function of the electron mean-free-path {lambda}{sub ei} compared to the spatial scales L. The isotropic and anisotropic contributions of the inverse bremsstrahlung heating are considered. Electron-electron collision terms are kept in the analysis, which allows us to consider with sufficient accuracy to describe plasmas with arbitrary atomic number Z. Practical numerical fits of the transport coefficients are proposed as functions of Z and the collisionality parameter {lambda}{sub ei}/L.

  7. Monte Carlo analysis of energy dependent anisotropy of bremsstrahlung x-ray spectra

    SciTech Connect

    Kakonyi, Robert; Erdelyi, Miklos; Szabo, Gabor

    2009-09-15

    The energy resolved emission angle dependence of x-ray spectra was analyzed by MCNPX (Monte Carlo N particle Monte Carlo) simulator. It was shown that the spectral photon flux had a maximum at a well-defined emission angle due to the anisotropy of the bremsstrahlung process. The higher the relative photon energy, the smaller the emission angle belonging to the maximum was. The trends predicted by the Monte Carlo simulations were experimentally verified. The Monte Carlo results were compared to both the Institute of Physics and Engineering in Medicine spectra table and the SPEKCALCV1.0 code.

  8. Neutron-proton bremsstrahlung as a possible probe of high-momentum component in nucleon momentum distribution

    NASA Astrophysics Data System (ADS)

    Xue, Hui; Xu, Chang; Yong, Gao-Chan; Ren, Zhongzhou

    2016-04-01

    Neutron-proton bremsstrahlung in intermediate energy nucleus-nucleus collisions is proposed as a possible probe to study the high-momentum component in nucleon momentum distribution of finite nucleus. Based on the Boltzmann-Uehling-Uhlenbeck (BUU) transport model, the effects of high-momentum component on the production of bremsstrahlung photons in the reaction of 12C+12 C collisions at different incident beam energies are studied. It is found that the high-momentum component increases the high-energy bremsstrahlung photon production remarkably. Furthermore, the ratio of photon production at different incident beam energies is suggested as a potential observable to probe the high-momentum component in nucleon momentum distribution of finite nucleus.

  9. Initial studies of Bremsstrahlung energy deposition in small-bore superconducting undulator structures in linac environments

    SciTech Connect

    Cremer, T.; Tatchyn, R.

    1995-12-31

    One of the more promising technologies for developing minimal-length insertion devices for linac-driven, single-pass Free Electron Lasers (FELs) operating in the x-ray range is based on the use of superconducting (SC) materials. In recent FEL simulations, for example, a bifilar helical SC device with a 2 cm period and 1.8 T field was found to require a 30 m saturation length for operation at 1.5{Angstrom} on a 15 GeV linac, more than 40% shorter than an alternative hybrid/permanent magnet (hybrid/PM) undulator. AT the same time, however, SC technology is known to present characteristic difficulties for insertion device design, both in engineering detail and in operation. Perhaps the most critical problem, as observed, e.g., by Madey and co-workers in their initial FEL experiments, was the frequent quenching induced by scattered electrons upstream of their (bifilar) device. Postulating that this quenching was precipitated by directly-scattered or bremsstrahlung-induced particle energy deposited into the SC material or into material contiguous with it, the importance of numerical and experimental characterizations of this phenomenon for linac-based, user-facility SC undulator design becomes evident. In this paper we discuss selected prior experimental results and report on initial EGS4 code studies of scattered and bremsstrahlung induced particle energy deposition into SC structures with geometries comparable to a small-bore bifilar helical undulator.

  10. Characterizing Hot Electron Generation and Transport via Bremsstrahlung Emission on the High Intensity OMEGA EP Laser

    NASA Astrophysics Data System (ADS)

    Peebles, J.; McGuffey, C.; Krauland, C.; Sorokovikova, A.; Qiao, B.; Krasheninnikov, S.; Beg, F. N.; Wei, M. S.; Stephens, R. B.; Chen, C. D.; Westover, B.; McLean, H. S.

    2014-10-01

    The investigation of high intensity laser generated fast electron beams is important for a number of High Energy Density Science applications, which include proton sources and fast ignition among others. A series of experimental campaigns performed using the kilojoule, 10-ps OMEGA EP laser closely examined the impact of a preformed plasma on laser plasma interaction and electron generation. Here we present the analysis of the measured bremsstrahlung x-ray radiation and the inferred results on fast electron characteristics. Simulations, performed with the Monte-Carlo code package ITS 3.0, generate the x-ray response of the target to an injected electron beam with a given temperature, energy and divergence angle. The simulated x-rays are then compared to those collected by the bremsstrahlung spectrometers, which allows us to characterize fast electrons created in the experiment. Preliminary results show a decrease in hot electron temperature with an increase in pre-pulse, which is further corroborated by magnetic electron and Cu-K α spectrometers. This work performed under the auspices of the US DOE under contracts DE-FOA-0000583 (FES, NNSA), DE-NA0002026 (NLUF) and DE-FC02-04ER54789 (FSC).

  11. Effect of degenerate particles on internal bremsstrahlung of Majorana dark matter

    NASA Astrophysics Data System (ADS)

    Okada, Hiroshi; Toma, Takashi

    2015-11-01

    Gamma-rays induced by annihilation or decay of dark matter can be its smoking gun signature. In particular, gamma-rays generated by internal bremsstrahlung of Majorana and real scalar dark matter is promising since it can be a leading emission of sharp gamma-rays. However in the case of Majorana dark matter, its cross section for internal bremsstrahlung cannot be large enough to be observed by future gamma-ray experiments if the observed relic density is assumed to be thermally produced. In this paper, we introduce some degenerate particles with Majorana dark matter, and show they lead enhancement of the cross section. As a result, increase of about one order of magnitude for the cross section is possible without conflict with the observed relic density, and it would be tested by the future gamma-ray experiments such as GAMMA-400 and Cherenkov Telescope Array (CTA). In addition, the constraints of perturbativity, positron observation by the AMS experiment and direct search for dark matter are discussed.

  12. Evaluation of Hepatic Angiography Procedures and Bremsstrahlung Imaging in Selective Internal Radiation Therapy: A Two-Year Single-Center Experience

    SciTech Connect

    Sebastian, A. J. Szyszko, T.; Al-Nahhas, A.; Nijran, K.; Tait, N. P.

    2008-05-15

    The imaging of Bremsstrahlung radiation is performed after hepatic radioembolization to assess the distribution of the injected radioactive material. This review assesses the role of Bremsstrahlung imaging and its relation to the angiographic procedure and technique in hepatic selective internal radiation therapy on 21 patients undergoing this procedure at a single center.

  13. Time-resolved x-ray pinhole camera with grazing incidence mirror to eliminate bremsstrahlung noise signal on Z

    SciTech Connect

    Nash, T. J.; Chandler, G. A.; Bailey, J. E.; Rochau, G.; Leeper, R. J.; Nielsen, D. S.; Moore, T.

    2006-10-15

    An on-axis time-resolved x-ray pinhole camera has been used on the 20 MA 100 ns driver Z to image the converging shock wave in dynamic Hohlraum experiments and to image pellet hot spots in inertial confinement fusion implosions. This instrument is susceptible to detecting significant amounts of pinch bremsstrahlung radiation with energies at hundreds of keV and yields of roughly 1 kJ. Quite often the bremsstrahlung noise signals have overwhelmed the desired x-ray images. In an effort to eliminate this large source of noise we have incorporated a 6 deg. gold-coated grazing incidence mirror into the time-resolved x-ray pinhole camera system. The mirror reflects soft x rays at energies under 2 keV but does not reflect bremsstrahlung radiation at hundreds of keV. We will present data from the instrument without the mirror showing large amounts of bremsstrahlung noise contamination and data with the mirror in the system showing greatly reduced noise levels.

  14. Proton-recoil detectors for time-of-flight measurements of neutrons with kinetic energies from some tens of keV to a few MeV

    NASA Astrophysics Data System (ADS)

    Beyer, R.; Grosse, E.; Heidel, K.; Hutsch, J.; Junghans, A. R.; Klug, J.; Légrády, D.; Nolte, R.; Röttger, S.; Sobiella, M.; Wagner, A.

    2007-06-01

    For experiments at the superconducting electron accelerator ELBE, where neutrons in the kinetic energy region from some tens of keV to a few MeV will be produced by bremsstrahlung, neutron-time-of-flight detectors have been developed. These detectors are made from the plastic scintillator material EJ-200. Efficiency calibration showed more than 10% efficiency for kinetic energies down to 30 keV. The calibration was done at the "accelerator facility for fast neutron research" at Physikalisch-Technische Bundesanstalt in Braunschweig, using pulsed quasi-monoenergetic neutron fields with a well-determined fluence. The low detection threshold was obtained by coincident readout of two Hamamatsu R2059-01 photomultiplier tubes per scintillator and by triggering just below the single-photo-electron peak of these photomultiplier tubes, which additionally gives a well-reproduceable detection threshold.

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

    SciTech Connect

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

    2009-05-07

    We present a compact, X-band, high-brightness accelerator design suitable for driving a precision gamma-ray source. Future applications of gamma-rays generated by Compton-scattering of laser and relativistic electron beams place stringent demands on the brightness and stability of the incident electron beam. This design identifies the beam parameters required for gamma-ray production, including position, and pointing stability. The design uses an emittance compensated, 11.4 GHz photo-gun and linac to generate 400 pC, 1-2 mm-mrad electron bunches at up to 250 MeV and 120 Hz repetition rate. The effects of jitter in the RF power system are analyzed as well as structure and optic misalignments. Finally, strategies for the mitigation of on-axis Bremsstrahlung noise are discussed.

  16. Efficient far-infrared thermal bremsstrahlung radiation from a heterojunction bipolar transistor

    SciTech Connect

    Chung, Pei-Kang; Yen, Shun-Tung

    2015-08-28

    We investigate the far-infrared thermal radiation properties of a heterojunction bipolar transistor. The device conveniently provides a high electric field for electrons to heat the lattice and the electron gas in a background with ions embedded. Because of very high effective temperature of the electron gas in the collector, the electron-ion bremsstrahlung makes efficient the thermal radiation in the far-infrared region. The transistor can yield a radiation power of 0.1 mW with the spectral region between 2 and 75 THz and a power conversion efficiency of 6 × 10{sup −4}. Such output contains a power of 20 μW in the low-frequency part (2–20 THz) of the spectrum.

  17. The interference effect of laser-assisted bremsstrahlung emission in Coulomb fields of two nuclei

    NASA Astrophysics Data System (ADS)

    Li, Ankang; Wang, Jiaxiang; Ren, Na; Wang, Pingxiao; Zhu, Wenjun; Li, Xiaoya; Hoehn, Ross; Kais, Sabre

    2013-09-01

    In this paper, the spontaneous bremsstrahlung emission from an electron scattered by two fixed nuclei in an intense laser field is investigated in detail based upon the Volkov state and the Dirac-Volkov propagator. It has been found that the fundamental harmonic spectrum from the electron radiation exhibits distinctive fringes, which is dependent not only upon the internucleus distance and orientation but also upon the initial energy of the electron and the laser intensity. By analyzing the differential cross section, we are able to explain these effects in terms of interference among the electron scattering by the nuclei. These results could have promising applications in probing the atomic or molecular dressed potentials in intense laser fields.

  18. Polarization bremsstrahlung of a hydrogen-like ion in a single crystal

    SciTech Connect

    Astapenko, V. A.

    2009-01-15

    Polarization bremsstrahlung (PB) that arises when a fast hydrogen-like ion is scattered in a single crystal is investigated theoretically. Four types of the process are analyzed that are caused by virtual excitation of electrons of the target and of the incident particle (IP), as well as by a coherent and incoherent interaction between the IP and the single crystal. The spectral, angular, and velocity (of the IP) characteristics of PB are calculated with regard to the spectral function of a photodetector. Optimal observation conditions and regions in which different types of PB are dominant are determined, and the dependence of these regions on the charge of the IP nucleus and of the target atoms is revealed.

  19. Potential enhancement of warm x-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.; Weber, B.V.

    1995-07-01

    The potential for generating intense bursts of war x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions. The calculation are compared with data from Gamble-II experiments and applied to two suggest Jupiter (60-MA, 5-MV, 100-ns) diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung which accompanies the warm x rays is a concern, then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately} 400 {mu}m for low-Z targets like aluminum and thinner than {approximately} 5 {mu}m for high-Z targets like gold.

  20. Potential enhancement of warm X-ray dose from a reflexing bremsstrahlung diode

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Cooperstein, G.

    1995-08-01

    The potential for generating intense bursts of warm x rays (20 to 60 keV) using electron reflexing diodes on pulsed-power accelerators is evaluated with the TIGER Monte Carlo code, showing that hundreds of kilojoules of warm x rays can be generated under idealized conditions, for a Jupiter (60-MA, 5-MV, 100-ns) class accelerator. The calculations are compared with data from Gamble-II experiments and applied to two suggested Jupiter diode configurations. If the simultaneous irradiation from the high-energy tail of the bremsstrahlung, which accompanies the warm x rays, is a concern then the reflexing technique is shown to be limited to the irradiation of targets thinner than {approximately}400 {mu}m for low-Z targets like aluminum and thinner than {approximately}5 {mu}m for high-Z targets like gold.

  1. Bremsstrahlung and Line Spectroscopy of Warm Dense Aluminum Plasma Generated by EUV Free Electron Laser

    SciTech Connect

    Zastrau, U; Fortmann, C; Faustlin, R; Bornath, T; Cao, L F; Doppner, T; Dusterer, S; Forster, E; Glenzer, S H; Gregori, G; Holl, A; Laarmann, T; Lee, H; Meiwes-Broer, K; Przystawik, A; Radcliffe, P; Redmer, R; Reinholz, H; Ropke, G; Tiggesbaumker, J; Thiele, R; Truong, N X; Uschmann, I; Toleikis, S; Tschentscher, T; Wierling, A

    2008-03-07

    We report on the novel creation of a solid density aluminum plasma using free electron laser radiation at 13.5 nm wavelength. Ultrashort pulses of 30 fs duration and 47 {micro}J pulse energy were focused on a spot of 25 {micro}m diameter, yielding an intensity of 3 x 10{sup 14} W/cm{sup 2} on the bulk Al-target. The radiation emitted from the plasma was measured using a high resolution, high throughput EUV spectrometer. The analysis of both bremsstrahlung and line spectra results in an estimated electron temperature of (30 {+-} 10) eV, which is in very good agreement with radiation hydrodynamics simulations of the laser-target-interaction. This demonstrates the feasibility of exciting plasmas at warm dense matter conditions using EUV free electron lasers and their accurate characterization by EUV spectroscopy.

  2. Double Higgs-boson bremsstrahlung from W and Z bosons at supercolliders

    NASA Astrophysics Data System (ADS)

    Barger, V.; Han, T.; Phillips, R. J. N.

    1988-11-01

    We calculate the production of two standard-model neutral Higgs bosons via bremsstrahlung from a single W or Z boson in pp or e+e- collisions at supercollider energies. Observation of these processes would test the predicted HHH, HVV, and HHVV couplings (V=W or Z). For e+e--->ZHH we extend previous cross-section calculations to a more comprehensive range of energies and Higgs-boson masses, that may be accessible to future machines; we also give final-particle distributions. In the pp case we present the first calculations of the processes pp-->HHVX the cross sections are comparable to other double Higgs-boson production processes for a range of energies and masses. The presence of W or Z accompanying the Higgs-boson pair has distinct practical advantages for triggering and for separating the final state from backgrounds.

  3. Bremsstrahlung X-ray spectra of Jupiter and Saturn - Predictions for future planetary spacecraft

    NASA Astrophysics Data System (ADS)

    Barbosa, D. D.

    1990-07-01

    Calculations of X-ray spectra due to bremsstrahlung from precipitating auroral electrons of Jupiter and Saturn are presented. The model assumes that a field-aligned potential drop accelerates a primary beam of electrons into the atmosphere where a population of secondary electrons having a power law energy dependence is generated. The spectrum at Jupiter is normalized to the soft X-ray observations of Metzger et al. (1983) at the low-energy end and constrained at the high-energy end by UV auroral energy requirements. The spectrum at Saturn is constructed by analogy to the Jovian case allowing for variation of the beam energy, energy flux, and scale size of the Saturnian aurora. The results indicate that a significant flux of X-rays is emanating from both planets which may serve as a basis for conducting planetary X-ray astronomy as a part of future spacecraft missions to the planets.

  4. Thick-target bremsstrahlung interpretation of short time-scale solar hard X-ray features

    NASA Technical Reports Server (NTRS)

    Emslie, A. G.

    1983-01-01

    Steady-state analyses of bremsstrahlung hard X-ray production in solar flares are appropriate only if the lifetime of the high energy electrons in the X-ray source is much shorter than the duration of the observed X-ray burst. For a thick-target nonthermal model, this implies that a full time-dependent analysis is required when the duration of the burst is comparable to the collisional lifetime of the injected electrons, in turn set by the lengths and densities of the flaring region. In this paper we present the results of such a time-dependent analysis, and we point out that the intrinsic temporal signature of the thick-target production mechanism, caused by the finite travel time of the electrons through the target, may indeed rule out such a mechanism for extremely short duration hard X-ray events.

  5. Application of visible bremsstrahlung to Z{sub eff} measurement on the Experimental Advanced Superconducting Tokamak

    SciTech Connect

    Chen, Yingjie; Wu, Zhenwei; Gao, Wei; Ti, Ang; Zhang, Ling; Jie, Yinxian; Zhang, Jizong; Huang, Juan; Xu, Zong; Zhao, Junyu

    2015-02-15

    The multi-channel visible bremsstrahlung measurement system has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to providing effective ion charge Z{sub eff} as a routine diagnostic, this diagnostic can also be used to estimate other parameters. With the assumption that Z{sub eff} can be seen as constant across the radius and does not change significantly during steady state discharges, central electron temperature, averaged electron density, electron density profile, and plasma current density profile have been obtained based on the scaling of Z{sub eff} with electron density and the relations between Z{sub eff} and these parameters. The estimated results are in good coincidence with measured values, providing an effective and convenient method to estimate other plasma parameters.

  6. Application of visible bremsstrahlung to Z(eff) measurement on the Experimental Advanced Superconducting Tokamak.

    PubMed

    Chen, Yingjie; Wu, Zhenwei; Gao, Wei; Ti, Ang; Zhang, Ling; Jie, Yinxian; Zhang, Jizong; Huang, Juan; Xu, Zong; Zhao, Junyu

    2015-02-01

    The multi-channel visible bremsstrahlung measurement system has been developed on Experimental Advanced Superconducting Tokamak (EAST). In addition to providing effective ion charge Zeff as a routine diagnostic, this diagnostic can also be used to estimate other parameters. With the assumption that Zeff can be seen as constant across the radius and does not change significantly during steady state discharges, central electron temperature, averaged electron density, electron density profile, and plasma current density profile have been obtained based on the scaling of Zeff with electron density and the relations between Zeff and these parameters. The estimated results are in good coincidence with measured values, providing an effective and convenient method to estimate other plasma parameters.

  7. Thick-target external-bremsstrahlung spectra of 147Pm and 35S β rays

    NASA Astrophysics Data System (ADS)

    Dhaliwal, A. S.; Powar, M. S.; Singh, M.

    1993-08-01

    External-bremsstrahlung spectra excited by soft β particles of 147Pm (Emaxβ=225 keV) and 35S (Emaxβ=167 keV) in targets of Al, Cu, Sn, and Pb have been studied. The experimental and theoretical results are compared in terms of the number of photons of energy k per m0c2 per unit photon yield to exclude the uncertainty in the source strength measurement and overcome the inherent inadequacy of the normalization procedure used by earlier workers. The results of present measurements for medium- and high-Z elements show better agreement with the theory of Tseng and Pratt [Phys. Rev. A 3, 1714 (1976)] than with Elwert's corrections [Ann. Phys. (N.Y.) 34, 78 (1939)] to the Bethe-Heitler theory [Proc. R. Soc. London Ser. A 14, 83 (1934)], particularly at the higher-energy ends. However, for low-Z elements, both theories are found to be adequate.

  8. Inverse bremsstrahlung cross section estimated within evolving plasmas using effective ion potentials

    NASA Astrophysics Data System (ADS)

    Wang, F.; Weckert, E.; Ziaja, B.

    2009-06-01

    We estimate the total cross sections for field-stimulated photoemissions and photoabsorptions by quasi-free electrons within a non-equilibrium plasma evolving from the strong coupling to the weak coupling regime. Such a transition may occur within laser-created plasmas, when the initially created plasma is cold but the heating of the plasma by the laser field is efficient. In particular, such a transition may occur within plasmas created by intense vacuum ultraviolet (VUV) radiation from a free-electron laser (FEL) as indicated by the results of the first experiments performed by Wabnitz at the FLASH facility at DESY. In order to estimate the inverse bremsstrahlung cross sections, we use point-like and effective atomic potentials. For ions modelled as point-like charges, the total cross sections are strongly affected by the changing plasma environment. The maximal change of the cross sections may be of the order of 75 at the change of the plasma parameters: inverse Debye length, κ, in the range κ = 0 - 3 Å-1 and the electron density, ρe, in the range ρe = 0.01 - 1 Å-3. These ranges correspond to the physical conditions within the plasmas created during the first cluster experiments performed at the FLASH facility at DESY. In contrast, for the effective atomic potentials the total cross sections for photoemission and photoabsorption change only by a factor of seven at most in the same plasma parameter range. Our results show that the inverse bremsstrahlung cross section estimated with the effective atomic potentials is not affected much by the plasma environment. This observation validates the estimations of the enhanced heating effect obtained by Walters, Santra and Greene. This is important as this effect may be responsible for the high-energy absorption within clusters irradiated with VUV radiation.

  9. Fermi LAT search for internal bremsstrahlung signatures from dark matter annihilation

    SciTech Connect

    Bringmann, Torsten; Huang, Xiaoyuan; Ibarra, Alejandro; Vogl, Stefan; Weniger, Christoph E-mail: x_huang@bao.ac.cn E-mail: stefan.vogl@tum.de

    2012-07-01

    A commonly encountered obstacle in indirect searches for galactic dark matter is how to disentangle possible signals from astrophysical backgrounds. Given that such signals are most likely subdominant, the search for pronounced spectral features plays a key role for indirect detection experiments; monochromatic gamma-ray lines or similar features related to internal bremsstrahlung, in particular, provide smoking gun signatures. We perform a dedicated search for the latter in the data taken by the Fermi gamma-ray space telescope during its first 43 months. To this end, we use a new adaptive procedure to select optimal target regions that takes into account both standard and contracted dark matter profiles. The behaviour of our statistical method is tested by a subsampling analysis of the full sky data and found to reproduce the theoretical expectations very well. The limits on the dark matter annihilation cross-section that we derive are stronger than what can be obtained from the observation of dwarf galaxies and, at least for the model considered here, collider searches. While these limits are still not quite strong enough to probe annihilation rates expected for thermally produced dark matter, future prospects to do so are very good. In fact, we already find a weak indication, with a significance of 3.1σ (4.3σ) when (not) taking into account the look-elsewhere effect, for an internal bremsstrahlung-like signal that would correspond to a dark matter mass of ∼150 GeV; the same signal is also well fitted by a gamma-ray line at around 130 GeV. Although this would be a fascinating possibility, we caution that a much more dedicated analysis and additional data will be necessary to rule out or confirm this option.

  10. Fermi LAT search for internal bremsstrahlung signatures from dark matter annihilation

    NASA Astrophysics Data System (ADS)

    Bringmann, Torsten; Huang, Xiaoyuan; Ibarra, Alejandro; Vogl, Stefan; Weniger, Christoph

    2012-07-01

    A commonly encountered obstacle in indirect searches for galactic dark matter is how to disentangle possible signals from astrophysical backgrounds. Given that such signals are most likely subdominant, the search for pronounced spectral features plays a key role for indirect detection experiments; monochromatic gamma-ray lines or similar features related to internal bremsstrahlung, in particular, provide smoking gun signatures. We perform a dedicated search for the latter in the data taken by the Fermi gamma-ray space telescope during its first 43 months. To this end, we use a new adaptive procedure to select optimal target regions that takes into account both standard and contracted dark matter profiles. The behaviour of our statistical method is tested by a subsampling analysis of the full sky data and found to reproduce the theoretical expectations very well. The limits on the dark matter annihilation cross-section that we derive are stronger than what can be obtained from the observation of dwarf galaxies and, at least for the model considered here, collider searches. While these limits are still not quite strong enough to probe annihilation rates expected for thermally produced dark matter, future prospects to do so are very good. In fact, we already find a weak indication, with a significance of 3.1σ (4.3σ) when (not) taking into account the look-elsewhere effect, for an internal bremsstrahlung-like signal that would correspond to a dark matter mass of ~150 GeV; the same signal is also well fitted by a gamma-ray line at around 130 GeV. Although this would be a fascinating possibility, we caution that a much more dedicated analysis and additional data will be necessary to rule out or confirm this option.

  11. Bremsstrahlung in Mo and Pt targets produced by {sup 90}Sr beta particles in the photon energy region of 1-100 keV

    SciTech Connect

    Singh, Amrit; Dhaliwal, A. S.

    2015-08-28

    Bremsstrahlung spectra in thick targets of Mo and Pt, produced by beta emitter {sup 90}Sr (end point energy = 546 keV) have been studied in the photon energy range of 1-100 keV. The experimentally measured bremsstrahlung spectra measured with Si(Li) detector were compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH) theory for ordinary bremsstrahlung (OB) and the modified Elwert factor (relativistic) Bethe-Heitler (F{sub mod}BH+PB) theory, which includes the polarization bremsstrahlung (PB) into total bremsstrahlung (BS). The present results indicate the correctness of F{sub mod}BH+PB theory in the low energy region, where the contributions of PB into BS are dominant, which is described in terms of stripped atom (SA) approximation. But at the middle and higher energy region of the bremsstrahlung spectrum, where the contribution of PB is negligible, the F{sub mod}BH theory is more close to the experimental results. Hence, it is clear that the production of PB in the low energy region, due to the dynamic response of the target atom suppresses the production of bremsstrahlung at higher energy ends.

  12. ETAII 6 MEV PEPPERPOT EMITTANCE MEASUREMENT

    SciTech Connect

    Paul, A C; Richardson, R; Weir, J

    2004-10-18

    We measured the beam emittance at the ETAII accelerator using a pepper-pot diagnostic at nominal parameters of 6 MeV and 2000 Amperes. During the coarse of these experiments, a ''new tune'' was introduced which significantly improved the beam quality. The source of a background pedestal was investigated and eliminated. The measured ''new tune'' emittance is {var_epsilon}= 8.05 {plus_minus} 0. 53 cm - mr or a normalized emittance of {var_epsilon}{sub n} = 943 {plus_minus} 63 mm - mr In 1990 the ETAII programmatic emphasis was on free electron lasers and the paramount parameter was whole beam brightness. The published brightness for ETAII after its first major rebuild was J = 1 - 3 x 10{sup 8} A/(m - rad){sup 2} at a current and energy of 1000-1400 Amperes and 2.5 MeV. The average normalized emittance derived from table 2 of that report is 864 mm-mr corresponding to a real emittance of 14.8 cm-mr.

  13. 46 CFR 56.50-70 - Gasoline fuel systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... or that required by 46 CFR 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). (3) Tubing fittings shall be of nonferrous drawn or forged metal and of the flared type... against excessive movement and vibration by the use of soft nonferrous metal liners or straps...

  14. 46 CFR 56.50-70 - Gasoline fuel systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... or that required by 46 CFR 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). (3) Tubing fittings shall be of nonferrous drawn or forged metal and of the flared type... against excessive movement and vibration by the use of soft nonferrous metal liners or straps...

  15. 46 CFR 56.50-70 - Gasoline fuel systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... or that required by 46 CFR 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). (3) Tubing fittings shall be of nonferrous drawn or forged metal and of the flared type... against excessive movement and vibration by the use of soft nonferrous metal liners or straps...

  16. 46 CFR 56.50-70 - Gasoline fuel systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... or that required by 46 CFR 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). (3) Tubing fittings shall be of nonferrous drawn or forged metal and of the flared type... against excessive movement and vibration by the use of soft nonferrous metal liners or straps...

  17. 46 CFR 56.50-70 - Gasoline fuel systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... or that required by 46 CFR 56.07-10(e) and 104.1.2 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). (3) Tubing fittings shall be of nonferrous drawn or forged metal and of the flared type... against excessive movement and vibration by the use of soft nonferrous metal liners or straps...

  18. 31 CFR 50.70 - Mandatory and discretionary recoupment.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... before December 31, 2010, the Secretary shall collect all required amounts by September 30, 2012; (2) For... 35 percent of any required amounts by September 30, 2012, and the remainder by September 30, 2017; and (3) For any act of terrorism that occurs on or after January 1, 2012, the Secretary shall...

  19. Proton-proton bremsstrahlung: Consequences of different on-shell-point conditions

    SciTech Connect

    Li, Yi; Liou, M. K.; Schreiber, W. M.; Gibson, B. F.

    2011-09-15

    Background: Proton-proton bremsstrahlung (pp{gamma}) is investigated both theoretically and experimentally. The pp{gamma} amplitudes can be classified according to the number and location of on-shell points at which they are evaluated. Quantitative understanding of the effect on the pp{gamma} cross section of using different on-shell-point conditions is lacking, but it is essential to identifying the photon emission mechanism governing the pp{gamma} process. Method: Four different pp{gamma} amplitudes, which include four-on-shell-point amplitudes and one-on-shell-point amplitude, are generated from a realistic one-boson-exchange (ROBE) model for pp scattering. These ROBE amplitudes are used to investigate the consequence of using different on-shell-point conditions in calculating the pp{gamma} cross sections. Purpose: We verify the validity of the ROBE pp{gamma} amplitudes. We explore similarities between the four-on-shell-point ROBE and two-u-two-t special (TuTts) soft-photon pp{gamma} amplitudes and important differences with the one-on-shell-point ROBE and Low pp{gamma} amplitudes. We demonstrate that the precision Kernfysisch Versneller Instituut (KVI) data can only be described by the four-on-shell-point (ROBE or TuTts) amplitude. We use the ROBE four-on-shell-point amplitude and one-on-shell-point amplitude to investigate systematically the effect of using different on-shell-point conditions to calculate the pp{gamma} cross section. Furthermore, we identify a general principle that governs the process. This general principle is also applicable to other bremsstrahlung processes involving the scattering of two identical nucleons. Results: (i) The four-on-shell-point ROBE (or TuTts) amplitude describes the high-precision KVI data much better than does the one-on-shell-point ROBE (or Low) amplitude. Although the contribution from the anomalous magnetic moment of the proton is very significant, it does not completely dominate the KVI pp{gamma} cross sections. (ii

  20. Characterization of 2 MeV, 4 MeV, 6 MeV and 18 MeV buildup caps for use with a 0.6 cubic centimeter thimble ionization chamber

    SciTech Connect

    Salyer, R.L.; VanDenburg, J.W.; Prinja, A.K.; Kirby, T.; Busch, R.; Hong-Nian Jow

    1996-07-01

    The purpose of this research is to characterize existing 2 MeV, 4 MeV and 6 MeV buildup caps, and to determine if a buildup cap can be made for the 0.6 cm{sup 3} thimble ionization chamber that will accurately measure exposures in a high-energy photon radiation field. Two different radiation transport codes were used to computationally characterize existing 2 MeV, 4 MeV, and 6 MeV buildup caps for a 0.6 cm{sup 3} active volume thimble ionization chamber: ITS, The Integrated TIGER Series of Coupled Electron-Photon Monte Carlo Transport Codes; and CEPXS/ONEDANT, A One-Dimensional Coupled Electron-Photon Discrete Ordinates Code Package. These codes were also used to determine the design characteristics of a buildup cap for use in the 18 MeV photon beam produced by the 14 TW pulsed power HERMES-III electron accelerator. The maximum range of the secondary electron, the depth at which maximum dose occurs, and the point where dose and collision kerma are equal have been determined to establish the validity of electronic equilibrium. The ionization chamber with the appropriate buildup cap was then subjected to a 4 MeV and a 6 MeV bremmstrahlung radiation spectrum to determine the detector response.

  1. Comparisons of Exact Results for the Virtual Correction to Bremsstrahlung in Electron-Positron Annihilation at High Energies

    NASA Astrophysics Data System (ADS)

    Yost, S. A.; Glosser, C.; Jadach, S.; Ward, B. F. L.

    2004-10-01

    We have compared the virtual corrections to single hard bremsstrahlung as calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent of these comparisons is to the leptonic tensor calculated by J.H. Kuhn and G. Rodrigo for radiative return. Agreement is found to within 10-5 or better as a fraction of the Born cross section for most of the range of photon energies.

  2. SU-E-E-08: Applications of the Quantization of Coupled Circuits in Radiation Physics (design of Klystron, Bremsstrahlung, Synchrotron)

    SciTech Connect

    Ulmer, W

    2015-06-15

    Purpose: During the past decade the quantization of coupled/forced electromagnetic circuits with or without Ohm’s resistance has gained the subject of some fundamental studies, since even problems of quantum electrodynamics can be solved in an elegant manner, e.g. the creation of quantized electromagnetic fields. In this communication, we shall use these principles to describe optimization procedures in the design of klystrons, synchrotron irradiation and high energy bremsstrahlung. Methods: The base is the Hamiltonian of an electromagnetic circuit and the extension to coupled circuits, which allow the study of symmetries and perturbed symmetries in a very apparent way (SU2, SU3, SU4). The introduction resistance and forced oscillators for the emission and absorption in such coupled systems provides characteristic resonance conditions, and atomic orbitals can be described by that. The extension to virtual orbitals leads to creation of bremsstrahlung, if the incident electron (velocity v nearly c) is described by a current, which is associated with its inductivitance and the virtual orbital to the charge distribution (capacitance). Coupled systems with forced oscillators can be used to amplify drastically the resonance frequencies to describe klystrons and synchrotron radiation. Results: The cross-section formula for bremsstrahlung given by the propagator method of Feynman can readily be derived. The design of klystrons and synchrotrons inclusive the radiation outcome can be described and optimized by the determination of the mutual magnetic couplings between the oscillators induced by the currents. Conclusions: The presented methods of quantization of circuits inclusive resistance provide rather a straightforward way to understand complex technical processes such as creation of bremsstrahlung or creation of radiation by klystrons and synchrotrons. They can either be used for optimization procedures and, last but not least, for pedagogical purposes with regard to

  3. Valine radiolysis by MeV ions

    NASA Astrophysics Data System (ADS)

    Da Silveira, Enio

    2016-07-01

    Valine, (CH3)2 CHCH (NH2) COOH, is a protein amino acid that has been identified in extraterrestrial environments and in the Murchison meteorite [1]. The knowledge of half-lives of small organic molecules under ionizing radiation is important for the setup of models describing the spread out of prebiotics across the Solar System or the Galaxy. We have investigated typical effects of MeV cosmic ray ions on prebiotic molecules in laboratory by impinging ions produced by the PUC-Rio Van de Graaff accelerator. Pure valine films, deposited by evaporation on KBr substrates, were irradiated by H ^{+}, He ^{+} and N ^{+} ion beams, from 0.5 to 1.5 MeV and up to a fluence of 10 ^{15} projectiles/cm ^{2}. The sample temperature was varied from 10 K to 300 K. The irradiation was interrupted several times for Mid-FTIR analysis of the sample. The main findings are: 1- The column density of the valine decreases exponentially with fluence. 2- In some cases, a second exponential appears in the beginning of irradiation; this feature has been attributed to sample compaction by the ion beam [2]. 3- Destruction cross sections of valine are in the 10 ^{-15} cm ^{2} range, while compaction cross sections are in the 10 ^{-14} cm ^{2} range. 4- Destruction cross section increases with the stopping power of the beam and also with the sample temperature. 5- Surprisingly, during the radiolysis of valine, just CO _{2} is seen by as a daughter molecule formed in the bulk. 6- After long beam fluence, also a CO peak appears in the infrared spectrum; this species is however interpreted as a fragment of the formed CO2 molecules. 7- Considering the flux ratio between laboratory experiments and actual galactic cosmic rays, half-life of valine is predicted for ISM conditions [3]. This work on pure valine is the first measurement of a series. New experiments are planned for determining cross sections of valine dissolved in H _{2}O or CO _{2}, inspired by the study performed for glycine [4]. [1] P

  4. FIRST DETECTION OF >100 MeV GAMMA-RAYS ASSOCIATED WITH A BEHIND-THE-LIMB SOLAR FLARE

    SciTech Connect

    Pesce-Rollins, M.; Omodei, N.; Petrosian, V.; Liu, Wei; Costa, Fatima Rubio da; Allafort, A.; Chen, Qingrong E-mail: nicola.omodei@stanford.edu

    2015-06-01

    We report the first detection of >100 MeV gamma-rays associated with a behind-the-limb solar flare, which presents a unique opportunity to probe the underlying physics of high-energy flare emission and particle acceleration. On 2013 October 11 a GOES M1.5 class solar flare occurred ∼9.°9 behind the solar limb as observed by STEREO-B. RHESSI observed hard X-ray (HXR) emission above the limb, most likely from the flare loop-top, as the footpoints were occulted. Surprisingly, the Fermi Large Area Telescope (LAT) detected >100 MeV gamma-rays for ∼30 minutes with energies up to 3 GeV. The LAT emission centroid is consistent with the RHESSI HXR source, but its uncertainty does not constrain the source to be located there. The gamma-ray spectra can be adequately described by bremsstrahlung radiation from relativistic electrons having a relatively hard power-law (PL) spectrum with a high-energy exponential cutoff, or by the decay of pions produced by accelerated protons and ions with an isotropic pitch-angle distribution and a PL spectrum with a number index of ∼3.8. We show that high optical depths rule out the gamma-rays originating from the flare site and a high-corona trap model requires very unusual conditions, so a scenario in which some of the particles accelerated by the CME shock travel to the visible side of the Sun to produce the observed gamma-rays may be at work.

  5. Inverse bremsstrahlung heating beyond the first Born approximation for dense plasmas in laser fields

    NASA Astrophysics Data System (ADS)

    Moll, M.; Schlanges, M.; Bornath, Th; Krainov, V. P.

    2012-06-01

    Inverse bremsstrahlung (IB) heating, an important process in the laser-matter interaction, involves two different kinds of interaction—the interaction of the electrons with the external laser field and the electron-ion interaction. This makes analytical approaches very difficult. In a quantum perturbative approach to the IB heating rate in strong laser fields, usually the first Born approximation with respect to the electron-ion potential is considered, whereas the influence of the electric field is taken exactly in the Volkov wave functions. In this paper, a perturbative treatment is presented adopting a screened electron-ion interaction potential. As a new result, we derive the momentum-dependent, angle-averaged heating rate in the first Born approximation. Numerical results are discussed for a broad range of field strengths, and the conditions for the applicability of a linear approximation for the heating rate are analyzed in detail. Going a step further in the perturbation series, we consider the transition amplitude in the second Born approximation, which enables us to calculate the heating rate up to the third order of the interaction strength.

  6. A Figure of Merit Comparison between Bremsstrahlung and Monoenergetic X-Ray Sources for Angiography.

    PubMed

    Boone, J M; Seibert, J A

    1994-01-01

    A figure of merit (FOM) has been developed which embodies parameters related to image quality in the numerator and radiation integral dose to the patient in the denominator. In this manner, maximizing image quality and minimizing radiation dose amounts to maximizing the FOM. Furthermore, the FOM is designed to be independent of x-ray exposure (number of photons used), and this eliminates one important parameter in an optimization scenario. Monoenergetic x-ray beams (0% bandwidth) are compared with conventional Bremsstrahlung x-ray sources from a tungsten target, for angiographic imaging systems using 144 mg/cm2 Csl image intensifiers as the detector. Thus the results are applicable to both digital subtraction angiography (DSA) and digital fluoroscopic procedures involving iodine-based contrast (e.g., roadmapping). The results demonstrate improvement factors (the ratio of the best FOM of the monoenergetic beam over the best FOM of the polyenergetic beam) ranging from 2.3 to 1.4. The improvement factors averaged over four iodine contrast thicknesses (50, 100, 500, and 1000 mg/cm2) were 1.61 (σ = 0.159) for the 10 cm thick patient, 1.68 (σ= 0.172) for the 20 cm thick patient, and 1.82 (σ= 0.186) for the 30 cm thick patient. The conclusions are that monoenergetic x-ray beams are capable of delivering the same image quality at about half the radiation dose to the patient compared to conventional X-ray tubes. PMID:21307470

  7. Conjugate observation of electron microburst groups by Bremsstrahlung X-ray and riometer techniques

    SciTech Connect

    Siren, J.C.; Rosenberg, T.J.; Detrick, D.; Lanzerotti, L.J.

    1980-12-01

    The first evidence is reported of simultaneous conjugate electron microburst group precipitation. Groups of bremsstrahlung X ray microbursts (E>25 keV) were observed during a substorm recovery phase by a balloon-borne scintillation counter over Roberval, Quebec, Canada. The microburst groups were accompanied one-to-one by time-delayed and broadened pulses of ionospheric absorption measured by a high sensitivity 30-MHz riometer at Siple Station, Antarctica (Lapprox. =4.1). For the interval of highest correlation, the absolute lag between the two data sets was 4 +- 1 s, to the limit of the relative timing accuracy. Approximately 2 s of the observed lag had been introduces by a low-pass filter in the riometer data acquistion unit. The remainder (2 s) was due to the ionospheric recombination process, which evidently had a response time (tauapprox.5 s) during this event much shorter than that ordinarily associated with the D region of the ionosphere. Model calculations of the ionspheric response to time-varying precipitation, derived from the profile of the measurement X ray flux, provide a consistent picture of simultaneous microburst group precipitation at conjugate points, absolute absorption and the electron spectrum derived from X rays, the degree of variation in absorption and X ray fluxes, and the characteristic ionospheric time constant at the altitude of maximum energy deposition.

  8. Hydramite II screening tests of potential bremsstrahlung converter debris shield materials

    SciTech Connect

    Reedy, E.D. Jr.; Hedemann, M.A.; Stark, M.A.

    1986-03-01

    Results of a brief test series aimed at screening a number of potential bremsstrahlung converter debris shield materials are reported. These tests were run on Sandia National Laboratories' Hydramite II accelerator using a diode configuration which produces a pinched electron beam. The materials tested include: (1) laminated Kevlar 49/polyester and E-glass/polyester composites, (2) a low density laminated Kevlar 49 composite, and (3) two types of through-the-thickness reinforced Kevlar 49 composites. As expected, tests using laminated Kevlar 49/polyester shields showed that shield permanent set (i.e., permanent deflection) increased with increasing tantalum conversion foil thickness and decreased with increasing shield thickness. The through-the-thickness reinforced composites developed localized, but severe, back surface damage. The laminated composites displayed little back surface damage, although extensive internal matrix cracking and ply delaminations were generated. Roughly the same degree of permanent set was produced in shields made from the low density Kevlar 49 composite and the Kevlar 49/polyester. The E-glass reinforced shields exhibited relatively low levels of permanent set.

  9. Spatial nonlinear absorption of Alfven waves by dissipative plasma taking account bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Taiurskii, A. A.; Gavrikov, M. B.

    2016-10-01

    We study numerically the nonlinear absorption of a plane Alfven wave falling on the stationary boundary of dissipative plasma. This absorption is caused by such factors as the magnetic viscosity, hydrodynamic viscosity, and thermal conductivity of electrons and ions, bremsstrahlung and energy exchange between plasma components. The relevance of this investigation is due to some works, published in 2011, with regard to the heating mechanism of the solar corona and solar wind generation as a result of the absorption of plasma Alfven waves generated in the lower significantly colder layers of the Sun. Numerical analysis shows that the absorption of Alfven waves occurs at wavelengths of the order of skin depth, in which case the classical MHD equations are inapplicable. Therefore, our research is based on equations of two-fluid magnetohydrodynamics that take into account the inertia of the electrons. The implicit difference scheme proposed here for calculating plane-parallel flows of two-fluid plasma reveals a number of important patterns of absorption and thus allows us to study the dependence of the absorption on the Alfven wave frequency and the electron thermal conductivity and viscosity, as well as to evaluate the depth and the velocity of plasma heating during the penetration of Alfven waves interacting with dissipative plasma.

  10. Bremsstrahlung and gamma ray lines in 3 scenarios of dark matter annihilation

    SciTech Connect

    Giacchino, Federica; Tytgat, Michel H.G.; Lopez-Honorez, Laura E-mail: llopezho@vub.ac.be

    2014-08-01

    Gamma ray spectral features are of interest for indirect searches of dark matter (DM). Following Barger et al. we consider 3 simple scenarios of DM that annihilates into Standard Model (SM) fermion pairs. Scenario 1 is a Majorana DM candidate coupled to a charged scalar, scenario 2 is a Majorana DM coupled to a charged gauge boson and scenario 3 is a real scalar DM coupled a charged vector-like fermion. As shown by Barger et al., these 3 scenarios share precisely the same internal Bremsstrahlung spectral signature into gamma rays. Their phenomenology is however distinct. In particular for annihilation into light SM fermions, in the chiral limit, the 2-body annihilation cross section is p-wave suppressed for the Majorana candidates while it is d-wave suppressed for the real scalar. In the present work we study the annihilation into 2 gammas, showing that these three scenarios have distinct, and so potentially distinguishable, spectral signatures into gamma rays. In the case of the real scalar candidate we provide a new calculation of the amplitude for annihilation into 2 gammas.

  11. Impact of x-ray dose on the response of CR-39 to 1-5.5 MeV alphas.

    PubMed

    Rojas-Herrera, J; Rinderknecht, H G; Zylstra, A B; Gatu Johnson, M; Orozco, D; Rosenberg, M J; Sio, H; Seguin, F H; Frenje, J A; Li, C K; Petrasso, R D

    2015-03-01

    The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray fluences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-Kα and Kβ x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula. PMID:25832223

  12. Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas

    DOE PAGESBeta

    Rojas-Herrera, J.; Rinderknecht, H. G.; Zylstra, A. B.; Gatu Johnson, M.; Orozco, D.; Rosenberg, M. J.; Sio, H.; Seguin, F. H.; Frenje, J. A.; Li, C. K.; et al

    2015-03-01

    The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray uences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-Kα and Kβ x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed tomore » x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.« less

  13. Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas

    SciTech Connect

    Rojas-Herrera, J. Rinderknecht, H. G.; Zylstra, A. B.; Gatu Johnson, M.; Orozco, D.; Rosenberg, M. J.; Sio, H.; Seguin, F. H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.

    2015-03-15

    The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray fluences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-K{sub α} and K{sub β} x-rays. The CR-39 detectors were then exposed to 1–5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.

  14. Impact of x-ray dose on the response of CR-39 to 1–5.5 MeV alphas

    SciTech Connect

    Rojas-Herrera, J.; Rinderknecht, H. G.; Zylstra, A. B.; Gatu Johnson, M.; Orozco, D.; Rosenberg, M. J.; Sio, H.; Seguin, F. H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.

    2015-03-01

    The CR-39 nuclear track detector is used in many nuclear diagnostics fielded at inertial confinement fusion (ICF) facilities. Large x-ray uences generated by ICF experiments may impact the CR-39 response to incident charged particles. To determine the impact of x-ray exposure on the CR-39 response to alpha particles, a thick-target bremsstrahlung x-ray generator was used to expose CR-39 to various doses of 8 keV Cu-Kα and Kβ x-rays. The CR-39 detectors were then exposed to 1-5.5 MeV alphas from an Am-241 source. The regions of the CR-39 exposed to x-rays showed a smaller track diameter than those not exposed to x-rays: for example, a dose of 3.0 ± 0.1 Gy causes a decrease of (19 ± 2)% in the track diameter of a 5.5 MeV alpha particle, while a dose of 60.0 ± 1.3 Gy results in a decrease of (45 ± 5)% in the track diameter. The reduced track diameters were found to be predominantly caused by a comparable reduction in the bulk etch rate of the CR-39 with x-ray dose. A residual effect depending on alpha particle energy is characterized using an empirical formula.

  15. Level Density of COBALT-57 in the Energy Region 1 Mev to 14 Mev

    NASA Astrophysics Data System (ADS)

    Mishra, Vivek

    The level density of ^{57 }Co is studied in the energy region of 1-14 MeV using three experimental techniques. Levels are counted in the resolved region, evaporation spectra are measured in the resolved to continuum region, and the coherence width is measured in the region of level overlap. Use of Hauser-Feshbach fits to the evaporation cross sections requires level densities of the residual nucleus. A two -parameter based Fermi gas form is used for the calculation of level density as a function of the nuclear excitation energy. This procedure enables level density calculation beyond the energy region in which the two fixed parameters provide the best fits to the data. A comparison is made between the level density obtained from the above described methods and the predictions of the microscopic model in an energy range of 1-20 MeV. This model utilizes a BCS pairing Hamiltonian and specific sets of single particle states and calculates numerical values of the level density. Comparisons are also made with level density of ^{57 }Co obtained in various other studies. Both the resolved level studies and the fits to the evaporation spectra were conducted using the ^{56}Fe(d,n)^{57 }Co and ^{57}Fe(p,n) ^{57}Co reactions. Standard neutron time-of-flight techniques including pulse shape discrimination for elimination of gamma -rays were employed. An energy resolution as good as 6 keV at 1-1.5 MeV neutron energy was obtained for high resolution measurements. For Ericson fluctuation measurements, the excitation functions corresponding to the ground state and the first two excited states of the residual nucleus in the ^{56}Fe(p,n) ^{56}Co reaction were obtained for lab angles between 0^circ and 150^circ. The ^{56}Fe(d,n) ^{57}Co reaction proves to be very selective in populating resolved states and includes substantial contributions from mechanisms other than the compound nuclear. The ^{57 }Fe(p,n)^{57}Co reaction populated 14 previously unknown levels. The fits to the

  16. Inverse bremsstrahlung heating rate in xenon clusters in the eikonal approximation

    SciTech Connect

    Dey, R.; Roy, A. C.

    2013-03-15

    We report inverse bremsstrahlung (IB) heating rates in the eikonal approximation (EA). The present analysis is performed using the plasma-screened Rogers and Debye potentials for Xe clusters with two different charge states (6 and 10). We compare the eikonal results with the first Born approximation (FBA) and classical-simulation (CL-sim) (Moll et al., Phys. Plasmas 19, 033303 (2012)) calculations for clusters in infrared light. Calculations have been performed for the field strength of 2.6 Multiplication-Sign 10{sup 8} V/cm. We find that compared to the FBA and CL-sim methods, the IB heating rate in the EA is less sensitive to the choice of the two potentials considered here. The present EA calculation shows that the influence of the inner structure of atomic ion on the heating rate is more prominent for the smaller ion charge (Xe{sup 6+}). In the case of low laser field approximation based on the elastic transport cross sections, it is seen that in contrast to the FBA and classical methods, the heating rate predicted by the EA does not deviate much all over the range of mean kinetic energy of electrons (20-500 eV) considered here for both the charge states of xenon (Xe{sup 6+} and Xe{sup 10+}). Furthermore, for the Rogers potential, EA is found to be in closer agreement with the classical method than the FBA. We also compare the results of the IB heating rate using the present and low-field approximation approaches to the above three methods and observe that the magnitudes of the IB heating rate calculated in the low field approximation are, in general, higher than the corresponding values predicted by the present approach for both the electron-ion potentials.

  17. Monte Carlo simulation of electron beam transport in graphite for composite application from MeV down to eV

    NASA Astrophysics Data System (ADS)

    Leger, J.; Yousfi, M.; Eichwald, O.; Loiseau, J. F.; Held, B.

    2005-04-01

    A Monte Carlo method, based on the treatment of the individual interactions and using the null collision technique to reduce the computation time, has been developed for the simulation of electron-matter interactions and validated for the case of graphite. Results describing the electron energy behaviour (energy deposition, energy distribution, electron density, etc) have been obtained for various initial energies (1 MeV, 500 keV, 100 keV, 10 keV and 1.6 keV) of the electron beam down to several lower limit or cutoff energies (100 keV, 25 keV, 5 keV and 10 eV). The specificity of the present simulation is, therefore, to cover quite a wide energy range (e.g. from 1 MeV down to 10 eV) during the electron transport in graphite. The electron-matter collision cross sections needed for the simulation over such an energy range (from 10 eV up to 1 MeV) are given. At higher energies, the elastic and inner-shell inelastic collision cross sections take into account the relativistic effects, and the photons resulting from the bremsstrahlung processes are considered as electron sources when they undergo Compton and photoelectric processes. At intermediate and low energy ranges, the inelastic collision cross sections for the conduction band excitations are obtained from a classical dielectric function model. The significant effect of the lowering of the cutoff energy on the deposited energy is emphasized, while the contribution to the deposited energy of the photon interactions is shown to be quite low in the case of the present initial beam energies.

  18. Effects of MeV ion beam on polymers

    SciTech Connect

    Evelyn, A.L.; Ila, D.; Zimmerman, R.L.; Bhat, K.; Poker, D.B.; Hensley, D.K.

    1997-12-01

    The electronic ({var_epsilon}{sub c}) and nuclear ({var_epsilon}{sub n}) stopping effects produced by 3.5 MeV and 5.0 MeV ion bombardment in polyvinylidine chloride (PVDC), polyethylene (PE) and polyethylene sulfide were studied and compared. To separate these effects the authors chose two bombardment energies and a thin film polymer stacking technique developed in house. The resulting stacked layered system consisting of each polymer was bombarded with 3.5 MeV and 5.0 MeV alpha particles. The layered system was selected such that the first few layers experience most of the effects of the electronic energy deposited and the last layer receives the effects of the nuclear stopping. The electrical conductance and the changes in the chemical structure were measured by direct resistivity measurements, Raman microprobe analysis, RBS, and FTIR. The post-irradiation characterization resolved the effects of the stopping powers on the polymer films.

  19. Comparison of measured and theoretical inverse bremsstrahlung and photoionization absorption of infrared radiation in a H-He plasma.

    NASA Technical Reports Server (NTRS)

    Billman, K. W.; Stallcop, J. R.; Rowley, P. D.; Presley, L. L.

    1972-01-01

    The absorption coefficients of 1.15- and 3.39-micrometer radiation for a homogeneous H-He plasma have been measured in a temperature and electron density range where the major absorption mechanisms are electron-ion inverse bremsstrahlung and neutral-atom photoionization. Measurements were made behind both the incident and reflected shock waves in a driven tube by recording the laser intensity transmitted along the tube diameter as a function of time. The measured values compare well with those obtained from theoretical calculations for a gas in thermodynamic equilibrium.

  20. Inverse Bremsstrahlung Stabilization of Noise in the Generation of Ultra-short Intense Pulses by Backward Raman Amplification

    SciTech Connect

    Richard L. Berger; Daniel S. Clark Andrei Solodov; Ernest J. Valeo; Nathaniel J. Fisch

    2003-11-06

    Inverse bremsstrahlung absorption of the pump laser beam in a backward Raman amplifier over the round-trip light transit time through the sub-critical density plasma can more than double the electron temperature of the plasma and produce time-varying axial temperature gradients. The resulting increased Landau damping of the plasma wave and detuning of the resonance can act to stabilize the pump against unwanted amplification of Langmuir noise without disrupting nonlinear amplification of the femtosecond seed pulse. Because the heating rate increases with the charge state Z, only low-Z plasmas (hydrogen, helium, or helium-hydrogen mixtures) will maintain a low enough temperature for efficient operation.

  1. The Virtual Correction to Bremsstrahlung in Results High-Energy e+e- Annihilation:. Comparison of Exact Results

    NASA Astrophysics Data System (ADS)

    Yost, S. A.; Glosser, C.; Jadach, S.; Ward, B. F. L.

    2005-04-01

    We have compared the virtual corrections to single hard bremsstrahlung as calculated by S. Jadach, M. Melles, B.F.L. Ward and S.A. Yost to several other expressions. The most recent of these comparisons is to the leptonic tensor calculated by J.H. Kühn and G. Rodrigo for radiative return. Agreement is found to within 10-5 or better, as a fraction of the Born cross section, for most of the range of photon energies. The massless limits have been shown to agree analytically to NLL order.

  2. PET/CT and Bremsstrahlung Imaging After 90Y DOTANOC Therapy for Rectal Net With Liver Metastases.

    PubMed

    Abdülrezzak, Ümmühan; Kula, Mustafa; Tutuş, Ahmet; Buyukkaya, Fikret; Karaca, Halit

    2015-10-01

    Peptide receptor radionuclide therapy with Lu or Y is promising with successful results in somatostatin receptor-positive tumors. In all radiation therapies, knowledge of the radiation dose received by the target, and other organs in the body is essential to evaluate the risks and benefits of any procedure. We report a case of liver metastases from a rectal neuroendocrine tumor, which was treated with Y DOTANOC. Posttreatment whole-body planar images were acquired through Bremsstrahlung radiations of Y on a γ-camera, and thoracolumbar PET/CT images were acquired on PET. PMID:26204211

  3. Production of 14 MeV neutrons by heavy ions

    DOEpatents

    Brugger, Robert M.; Miller, Lowell G.; Young, Robert C.

    1977-01-01

    This invention relates to a neutron generator and a method for the production of 14 MeV neutrons. Heavy ions are accelerated to impinge upon a target mixture of deuterium and tritium to produce recoil atoms of deuterium and tritium. These recoil atoms have a sufficient energy such that they interact with other atoms of tritium or deuterium in the target mixture to produce approximately 14 MeV neutrons.

  4. Constraints on Cosmological Parameters From The Sunyaev-Zel'dovich Effect and Thermal Bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Molnar, S. M.; Mushotzky, R. F.; White, Nicholas E. (Technical Monitor)

    2000-01-01

    We discuss the possibility of constraining cosmological parameters using the Sunyaev-Zel'dovich (SZ) effect and thermal bremsstrahlung caused by intra-cluster gas in clusters of galaxies. The new generation of X-ray satellites and ground based interferometers dedicated to SZ observations will enable one to reduce uncertainties in these measurements, and thus make this method potentially quite promising in the near future. The importance of this method is that, unlike most other methods, it is based on physical principles, no 'standard candles' or 'rulers' needed. We estimate the accuracy achievable in the determination of the matter density, OMEGA(sub m), the cosmological constant, OMEGA(sub LAMBDA), and the Hubble constant, h, using the redshift dependence of the angular diameter distance derived from observations in the near future. We demonstrate that constraints from the angular diameter distance are orthogonal to those from Cosmic Microwave Background (CMB) fluctuations in the parameter space defined by OMEGA(sub m), OMEGA(sub LAMBDA), and h. Assuming a statistical error of five percent in the angular diameter distance for each cluster in a sample of five hundred clusters, we show that the redshift dependence of the angular diameter distance combined with constraints from CMB fluctuations can put stringent constraints on OMEGA(sub m) (+/- 0.03), OMEGA(sub LAMBDA) (+/- 0.03) and h (+/- 0.03, 3(sigma) errors). We also show that, with as few as 50 clusters between redshifts 0.01 and 1.5 with an assumed 10% statistical error in the angular diameter distance determination, one can distinguish between models with zero cosmological constant and spatially flat models with a cosmological constant with high confidence level (independently from the supernova results) and put meaningful constraints on OMEGA(sub m) (+/- 0.01), OMEGA(sub LAMBDA) (+/- 0.01) and h (+/- 0.01, 3(sigma) errors). With the expected advances in observational technology, we will be limited by

  5. Studies on the effect of the axial magnetic field on the x-ray bremsstrahlung in a 2.45 GHz permanent magnet microwave ion source

    SciTech Connect

    Kumar, Narender; Rodrigues, G. Lakshmy, P. S.; Mathur, Y.; Ahuja, R.; Kanjilal, D.; Baskaran, R.

    2014-02-15

    A compact microwave ion source has been designed and developed for operation at a frequency of 2.45 GHz. The axial magnetic field is based on two permanent magnet rings, operating in the “off-resonance” mode and is tunable by moving the permanent magnets. In order to understand the electron energy distribution function, x-ray bremsstrahlung has been measured in the axial direction. Simulation studies on the x-ray bremsstrahlung have been carried out to compare with the experimental results. The effect of the axial magnetic field with respect to the microwave launching position and the position of the extraction electrode on the x-ray bremsstrahlung have been studied.

  6. Yield constants of external Bremsstrahlung excited by 90Sr- 90Y, 147Pm and 204Tl in CdO and lead compounds

    NASA Astrophysics Data System (ADS)

    Manjunatha, H. C.; Rudraswamy, B.

    2011-03-01

    Bremsstrahlung yield of 90Sr- 90Y, 147Pm and 204Tl in CdO, PbF 2, Pb(NO 3) 2 and PbCl 2 has been measured using 3.8 cm×3.8 cm NaI(Tl) crystal and is compared with Tseng and Pratt theory. The Z dependence of external Bremsstrahlung (EB) is also measured and compared with the theory. The Bremsstrahlung photon yield and energy yield constants ( K' and K) are evaluated from the measured and theoretical yields. These values decrease with the increase in Emax of beta. The evaluated K' and K may be useful to calculate the photon yield and the energy yield, when these beta particles interact with the compounds of modified atomic number ranging from 42 to 73.

  7. Time-dependent 2.2 MeV and 0.5 MeV lines from solar flares

    NASA Technical Reports Server (NTRS)

    Wang, H. T.; Ramaty, R.

    1975-01-01

    The time dependences of the 2.2 MeV and 0.51 MeV gamma ray lines from solar flares are calculated and the results are compared with observations of the 1972, August 4 and 7 flares. Time lag between the nuclear reactions and the formation of these two lines are caused, respectively, by capture of the neutrons, and by deceleration of the positrons and decay of the radioactive nuclei. Results show that the calculation is consistent with the observed rise of the 2.2 MeV line on August 4, and it does not require different time dependences for the accelerated protons and electrons in the flare region. The above lags can explain the delayed gamma ray emission observed on August 7. Positrons of energies greater than about 10 MeV could be detected in interplanetary space following large solar flares.

  8. Dose calculations using MARS for Bremsstrahlung beam stops and collimators in APS beamline stations.

    SciTech Connect

    Dooling, J.; Accelerator Systems Division

    2010-11-01

    The Monte Carlo radiation transport code MARS is used to model the generation of gas bremsstrahlung (GB) radiation from 7-GeV electrons which scatter from residual gas atoms in undulator straight sections within the Advanced Photon Source (APS) storage ring. Additionally, MARS is employed to model the interactions of the GB radiation with components along the x-ray beamlines and then determine the expected radiation dose-rates that result. In this manner, MARS can be used to assess the adequacy of existing shielding or the specifications for new shielding when required. The GB radiation generated in the 'thin-target' of an ID straight section will consist only of photons in a 1/E-distribution up to the full energy of the stored electron beam. Using this analytical model, the predicted GB power for a typical APS 15.38-m insertion device (ID) straight section is 4.59 x 10{sup -7} W/nTorr/mA, assuming a background gas composed of air (Z{sub eff} = 7.31) at room temperature (293K). The total GB power provides a useful benchmark for comparisons between analytical and numerical approaches. We find good agreement between MARS and analytical estimates for total GB power. The extended straight section 'target' creates a radial profile of GB, which is highly peaked centered on the electron beam. The GB distribution reflects the size of the electron beam that creates the radiation. Optimizing the performance of MARS in terms of CPU time per incident trajectory requires the use of a relatively short, high-density gas target (air); in this report, the target density is {rho}L = 2.89 x 10{sup -2} g/cm{sup 2} over a length of 24 cm. MARS results are compared with the contact dose levels reported in TB-20, which used EGS4 for radiation transport simulations. Maximum dose-rates in 1 cc of tissue phantom form the initial basis for comparison. MARS and EGS4 results are approximately the same for maximum 1-cc dose-rates and attenuation in the photon-dominated regions; for thicker

  9. Applications of advanced kinetic collisional radiative modeling and Bremsstrahlung emission to quantitative impurity analysis on the National Spherical Torus Experiment

    NASA Astrophysics Data System (ADS)

    Muñoz Burgos, J. M.; Tritz, K.; Stutman, D.; Bell, R. E.; LeBlanc, B. P.; Sabbagh, S. A.

    2015-12-01

    An advanced kinetic collisional radiative model is used to predict beam into plasma charge-exchange visible and extreme UV (XUV ∽ 50 -700 Å ) light emission to quantify impurity density profiles on NSTX. This kinetic model is first benchmarked by predicting line-of-sight integrated emission for the visible λ = 5292.0 Å line of carbon (C VI n = 8 → 7), and comparing these predictions to absolute calibrated measurements from the active CHarge-Exchange Recombination Spectroscopy diagnostic (CHERS) on NSTX. Once benchmarked, the model is used to predict charge-exchange emission for the 182.1 Å line of carbon (C VI n = 3 → 2) that is used to scale Bremsstrahlung continuum emission in the UV/XUV region. The scaled Bremsstrahlung emission is used as a base to estimate an absolute intensity calibration curve of a XUV Transmission Grating-based Imaging Spectrometer (TGIS) diagnostic installed on the National Spherical Torus Experiment (NSTX and upgrade NSTX-U). The TGIS diagnostic operates in the wavelength region ∽ 50 -700 Å , and it is used to measure impurity spectra from charge-exchange emission. Impurity densities are estimated by fitting synthetic emission from the kinetic charge-exchange model to TGIS spectral measurements.

  10. Effect of frequency tuning on bremsstrahlung spectra, beam intensity, and shape in the 10 GHz NANOGAN electron cyclotron resonance ion source

    SciTech Connect

    Rodrigues, G. Mal, Kedar; Kumar, Narender; Lakshmy, P. S.; Mathur, Y.; Kumar, P.; Kanjilal, D.; Roy, A.; Baskaran, R.

    2014-02-15

    Studies on the effect of the frequency tuning on the bremsstrahlung spectra, beam intensities, and beam shape of various ions have been carried out in the 10 GHz NANOGAN ECR ion source. The warm and cold components of the electrons were found to be directly correlated with beam intensity enhancement in case of Ar{sup 9+} but not so for O{sup 5+}. The warm electron component was, however, much smaller compared to the cold component. The effect of the fine tuning of the frequency on the bremsstrahlung spectrum, beam intensities and beam shape is presented.

  11. Elastic Neutron Scattering at 96 MeV

    NASA Astrophysics Data System (ADS)

    Hildebrand, A.; Blomgren, J.; Ataç, A.; Bergenwall, B.; Johansson, C.; Klug, J.; Mermod, P.; Nilsson, L.; Pomp, S.; Österlund, M.; Dangtip, s.; Tippawan, U.; Phansuke, P.; Jonsson, O.; Renberg, P.-U.; Prokofiev, A.; Nadel-Turonski, P.; Elmgren, K.; Olsson, N.; Blideanu, V.; Le Brun, C.; Lecolley, J.-F.; Lecolley, F.-R.; Louvel, M.; Marie-Noury, N.; Schweitzer, C.; Eudes, Ph.; Haddad, F.; Lebrun, C.; Koning, A. J.

    2005-05-01

    A facility for detection of scattered neutrons in the energy interval 50-130 MeV, SCANDAL (SCAttered Nucleon Detection AssembLy), has recently been installed at the 20 - 180-MeV neutron beam line of The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12C, 16O, 56Fe, 89Y, and 208Pb has been studied at 96 MeV in the 10 - 70° interval. The results from 12C and 208Pb have recently been published,6 while the data from 16O, 56Fe, and 89Y are under analysis. The achieved energy resolution, 3.7 MeV, is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3%, is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions, based on phenomenology or microscopic theory. Applications for these measurements are nuclear-waste incineration, single-event upsets in electronics, and fast-neutron therapy.

  12. Solar Gamma Rays Above 8 MeV

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Crannell, H.; Ramaty, R.

    1978-01-01

    Processes which lead to the production of gamma rays with energy greater than 8 MeV in solar flares are reviewed and evaluated. Excited states produced by inelastic scattering, charge exchange, and spallation reactions in the abundant nuclear species are considered in order to identify nuclear lines which may contribute to the Gamma ray spectrum of solar flares. The flux of 15.11 MeV Gamma rays relative to the flux of 4.44 MeV Gamma rays from the de-excitation of the corresponding states in C12 is calculated for a number of assumed distributions of exciting particles. This flux ratio is a sensitive diagnostic of accelerated particle spectra. Other high energy nuclear levels are not so isolated as the 15.11 MeV state and are not expected to be so strong. The spectrum of Gamma rays from the decay of Pi dey is sensitive to the energy distribution of particles accelerated to energies greater than 100 MeV.

  13. Anomalous magnetic moment contributions to NN bremsstrahlung in the soft-photon approximation

    SciTech Connect

    Gibson, B.F.; Penninga, T.D.; Timmermans, R.G.E.; Liou, M.K.

    2005-05-06

    The soft photon approximation (SPA), which is relativistic and based upon a fundamental theorem for photon emission, is applied to explore two separate nucleon-nucleon bremsstrahlung (NN{gamma}) processes: pp{gamma} and np{gamma}. They are examined together in an effort to understand the mechanism which governs photon emission from these basic two-nucleon systems. In this investigation we focus upon the effect of the anomalous magnetic moments of the proton ({kappa}p) and the neutron ({kappa}n). In our SPA calculation we use the standard Low amplitude M{sub {mu}}{sup Low} as derived by Nyman plus the more recently developed amplitude M{sub {mu}}{sup TuTts}, referred to as the two-u-two-t special (TuTts) amplitude. The amplitude M{sub {mu}}{sup TuTts} is identical to the amplitude M{sub {mu}}{sup Low} through order K0 in the soft-photon expansion. However, M{sub {mu}}{sup TuTts} includes an additional term M{sub {mu}}{sup (3)}(K{sup 1}; {kappa}) (plus higher order terms). The term M{sub {mu}}{sup (3)}(K{sup 1}; {kappa}) is of order K1 in the soft-photon expansion and it is a function of {kappa}p and {kappa}n. Using the amplitudes M{sub {mu}}{sup TuTts} and M{sub {mu}}{sup Low}, we have calculated pp{gamma} and np{gamma} cross sections as a function of photon angle {psi}{gamma} with and without contributions from {kappa}p and {kappa}n. Comparison with available pp{gamma} data has been made; in particular, the contribution from M{sub {mu}}{sup (3)}(K{sup 1}; {kappa}) has been investigated. Results will be presented and discussed which relate to the following: (i) The anomalous magnetic moment effect is significant in pp{gamma}; however, it is small in np{gamma}. That is, the two amplitudes M{sub {mu}}{sup TuTts} and M{sub {mu}}{sup Low} yield very similar np{gamma} cross sections, but they predict very different pp{gamma} cross sections. (ii) M{sub {mu}}{sup TuTts} appears to provide a better SPA than M{sub {mu}}{sup Low} in the case of pp{gamma}. Because {kappa

  14. 10MeV 25KW industrial electron LINAC

    NASA Astrophysics Data System (ADS)

    Kamino, Y.

    1998-06-01

    A 10MeV 25KW plus class electron LINAC was developed for sterilisation of medical devices. The LINAC composed of a standing wave type single cavity prebuncher and a 2m electro-plated travelling wave guide uses a 5MW 2856MHz pulse klystron as an RF source and provides 25KW beam power at the Ti alloy beam window stably after the energy analysing magnet with 10MeV plus-minus 1 MeV energy slit. The practical maximum beam power reached 29 KW and this demonstrated the LINAC as one of the most powerful S-band electron LINACs in the world. The control of the LINAC is fully automated and the "One-Button Operation" is realised, which is valuable for easy operation as a plant system. 2 systems have been delivered and are being operated stably.

  15. Defects and diffusion in MeV implanted silicon

    SciTech Connect

    Venezia, V. C.; Haynes, T. E.; Agarwal, Aditya; Gossmann, H.-J.; Pelaz, L.; Jacobson, D. C.; Eaglesham, D. J.; Duggan, J. L.

    1999-06-10

    In this work we demonstrate that the defects that are created by 2-MeV Si ions can interact with dopant atoms both during implantation and during post-implant annealing. We show that the interstitials and vacancies created during MeV Si implantation result in a radiation enhanced diffusion of B and Sb markers, respectively, when the temperature of implantation is above the threshold temperature for formation of mobile dopant complexes. With the use of these dopant markers we also demonstrate that a vacancy-rich near surface region results during post-implant annealing of MeV implanted silicon. The depth distribution and the thermal evolution of clustered vacancies was measured by a Au labeling technique.

  16. Photon detector for MEGA. [53 MeV

    SciTech Connect

    Gagliardi, C.A.; Tribble, R.E.

    1992-01-01

    The MEGA photon detector is designed to observe the 52.83-MeV photon produced in a [mu] [yields] e[gamma] decay with an energy resolution of 1.25 MeV, a position resolution of 2 [times] 5 mm[sup 2], a directional resolution of 10[degree], a time resolution of 500 ps, and an efficiency of about 5.4%. It will consist of three independent concentric cylindrical pair spectrometers mounted within a 1.5 T magnetic field produced by a superconducting solenoid magnet. Each pair spectrometer includes two thin Pb foils to convert photons into e[sup +]e[sup [minus

  17. Earth albedo neutrons from 10 to 100 MeV.

    NASA Technical Reports Server (NTRS)

    Preszler, A. M.; Simnett, G. M.; White, R. S.

    1972-01-01

    We report the measurement of the energy and angular distributions of earth albedo neutrons from 10 to 100 MeV at 40 deg N geomagnetic latitude from a balloon at 120,000 ft, below 4.65 g/sq cm. The albedo-neutron omnidirectional energy distribution is flat to 50 MeV, then decreases with energy. The absolute neutron energy distribution is of the correct strength and shape for the albedo neutrons to be the source of the protons trapped in earth's inner radiation belt.

  18. Systematization of the yields of products of photonuclear reactions on enriched-tin targets at the bremsstrahlung-photon endpoint energy of 4.5 GeV

    SciTech Connect

    Balabekyan, A. R.

    2008-11-15

    Yields of photonuclear-reaction products formed in targets from separated tin isotopes under the effect of beams of bremsstrahlung photons whose endpoint energy is 4.5 GeV were investigated. The systematization performed on this basis revealed an isoscaling character of the behavior of the production yields for various regions of reaction-product masses.

  19. Time-dependent 2.2-MeV and 0.5-MeV lines from solar flares

    NASA Technical Reports Server (NTRS)

    Wang, H. T.; Ramaty, R.

    1975-01-01

    The time dependences of the 2.2- and 0.51-MeV gamma-ray lines from solar flares are calculated, and the results are compared with observations of the 1972 August 4 and 7 flares. The time lag between the nuclear reactions and the formation of these two lines is caused by capture of the neutrons and subsequent deceleration of the positrons and decay of the radioactive nuclei. Our main results are that the calculation is consistent with the observed rise of the 2.2-MeV line on August 4, and it does not require different time dependences for the accelerated protons and high-energy electrons in the flare region. The above lags can explain the delayed gamma-ray emission observed on August 7. Positrons of energies greater than about 10 MeV could be detected in interplanetary space following large solar flares.

  20. Measurements and effects of backstreaming ions produced at bremsstrahlung converter target in Dragon-I linear induction accelerator

    SciTech Connect

    Yu Haijun; Zhu Jun; Chen Nan; Xie Yutong; Jiang Xiaoguo; Jian Cheng

    2010-04-15

    Positive ions released from x-ray converter target impacted by electron beam of millimeter spot size can be trapped and accelerated in the incident beam's potential well. As the ions move upstream, the beam will be pinched first and then defocused at the target. Four Faraday cups are used to collect backstreaming ions produced at the bremsstrahlung converter target in Dragon-I linear induction accelerator (LIA). Experimental and theoretical results show that the backstreaming positive ions density and velocity are about 10{sup 21}/m{sup 3} and 2-3 mm/{mu}s, respectively. The theoretical and experimental results of electron beam envelope with ions and without ions are also presented. The discussions show that the backstreaming positive ions will not affect the electron beam focusing and envelope radius in Dragon-I LIA.

  1. Measurements of the fast electron bremsstrahlung emission during electron cyclotron resonance heating in the HL-2A tokamak

    SciTech Connect

    Zhang, Y. P.; Liu, Yi; Song, X. Y.; Yuan, G. L.; Chen, W.; Ji, X. Q.; Ding, X. T.; Yang, J. W.; Zhou, J.; Li, X.; Yang, Q. W.; Duan, X. R.; Pan, C. H.; Liu, Y.

    2010-10-15

    A fast electron bremsstrahlung (FEB) diagnostic technique based on cadmium telluride (CdTe) detector has been developed recently in the HL-2A tokamak for measurements of the temporal evolution of FEB emission in the energy range of 10-200 keV. With a perpendicular viewing into the plasma on the equatorial plane, the hard x-ray spectra with eight different energy channels are measured. The discrimination of the spectra is implemented by an accurate spectrometry. The system also makes use of fast digitization and software signal processing technology. An ambient environment of neutrons, gammas, and magnetic disturbance requires careful shielding. During electron cyclotron resonance heating, the generation of fast electrons and the oscillations of electron fishbone (e-fishbone) have been found. Using the FEB measurement system, it has been experimentally identified that the mode strongly correlates with the electron cyclotron resonance heating produced fast electrons with 30-70 keV.

  2. Polarization bremsstrahlung of fast electrons on metal nanospheres in a dielectric matrix in view of plasmon interference effects

    NASA Astrophysics Data System (ADS)

    Astapenko, V. A.; Sakhno, S. V.; Krotov, Yu A.

    2016-07-01

    The paper is devoted to the theoretical analysis of polarization bremsstrahlung (PB) [1] due to scattering of fast electrons by a metal nanosphere embedded in a dielectric matrix in a frequency region in the vicinity of dipole and quadrupole plasmon resonances. Here we take into account plasmon interference effects that arise in the frequency-angular distribution of PB. These effects are a consequence of interrelation between contributions to PBs due to a plasmon on the sphere surface of different multipolarity. Our approach is based on the Fermi method of equivalent photons [2] and the Mie theory of radiation scattering by small metal particles [3]. It is shown that taking into account plasmon interference in the PB differential cross-section results in specific features in the spectral distribution of an emitted photon that depend strongly on the radiation angle and nanosphere radius.

  3. Studies of total bremsstrahlung in thick targets of Al, Ti, Sn and Pb for 90Sr beta particles in the photon energy region of 1-100 keV

    NASA Astrophysics Data System (ADS)

    Singh, Amrit; Dhaliwal, A. S.

    2016-02-01

    Total bremsstrahlung (BS) spectra in thick targets of Al, Ti, Sn and Pb produced by beta emitter 90Sr (End point energy=546 keV) are studied in the photon energy range of 1-100 keV. The experimentally measured BS spectra are compared with the theoretical spectral distributions calculated from Elwert corrected (non relativistic) Bethe-Heitler [EBH] theory, modified Elwert factor (relativistic) Bethe-Heitler [Fmod BH] theory for ordinary bremsstrahlung (OB) and the Avdonina and Pratt [Fmod BH+PB] theory, which include the contribution of polarization bremsstrahlung (PB) into OB. The present results are indicating the correctness of Fmod BH+PB theory in the low energy region, where PB dominates into the BS, but at the middle and higher photon energy region of the bremsstrahlung spectrum, the Fmod BH theory is more close to the experimental results. The description of the bremsstrahlung process in stripped atom (SA) approximation, which indicates the suppression of the bremsstrahlung at higher energy ends due to the production of PB in the low energy region, needs further considerations. Hence, the present measurements for BS for different target materials indicates that the considerations of the screening effects along with other secondary effects during the interaction of incident electrons with the target nuclei are important while describing the production of bremsstrahlung, particularly for the higher energy regions.

  4. The 400 MeV Linac Upgrade at Fermilab

    SciTech Connect

    Noble, R.J.

    1992-12-01

    The Fermilab Linac Upgrade in planned to increase the energy of the H{sup {minus}} linac from 200 to 400 MeV. This is intended to reduce the incoherent space-charge tuneshift at injection into the 8 GeV Booster which limit either the brightness or the total intensity of the beam. The Linac Upgrade will be achieved by replacing the last four 201.25 MHs drift-tube linac (DTL) tanks which accelerate the beam from 116 to 200 MeV, with seven 805 MRs side-coupled cavity modules operating at an average axial field of about 7.5 MV/meter. This will allow acceleration to 400 MeV in the existing Linac enclosure. Each accelerator module will be driven with a 12 MW klystron-based rf power supply. Three of seven accelerator modules have been fabricated, power tested and installed in their temporary location adjacent to the existing DTL. All seven RF Modulators have been completed and klystron installation has begun. Waveguide runs have completed from the power supply gallery to the accelerator modules. The new linac will be powered in the temporary position without beam in order to verify overall system reliability until the laboratory operating schedule permits final conversion to 400 MeV operation.

  5. 150 MeV proton medical cyclotron design study.

    PubMed

    Burleigh, R J; Clark, D J; Flood, W S

    1975-01-01

    A brief design study has been done for a 150 MeV proton sector cyclotron. The object was to minimize cost but maintain good reliability and easy maintenance. The use of the proton beam would be for therapy, radiography and isotope production.

  6. Inclusive proton reactions at 164 MeV

    NASA Astrophysics Data System (ADS)

    Segel, R. E.; Chen, T.; Rutledge, L. L., Jr.; Maher, J. V.; Wiggins, John; Singh, P. P.; Debevec, P. T.

    1982-12-01

    Singles proton, deuteron, triton, 3He, and alpha spectra resulting from the bombardment of 27Al, 58Ni, 62Ni, and 208Pb targets were measured. Data were taken over the angular range 25°-150°. Most of the data were taken at a bombarding energy of 164 MeV; some data were taken at 100 MeV. The ratios of fast (>30 MeV) particle yields are p:d:t:3He:α~100:10:1:1:1. The deuteron spectra fall off more sharply with exit particle energy than do the proton spectra while tritons fall still more sharply, and the fast 3He and α spectra are similar in shape to the triton spectra. Fast particle angular distributions are all forward peaked with the forward peaking increasing with increasing outgoing particle energy. Angular distributions for the different particle species are quite similar and shapes of both spectral and angular distributions are rather independent of target. Proton and alpha evaporation peaks are prominent, deuterons less so, and evaporation peaks are not apparent in the triton and 3He spectra. NUCLEAR REACTIONS 164, 100 MeV p on 27Al, 58Ni, 62Ni, 208Pb; measured outgoing p, d, t, 3He, α spectra 25°<=θ<=150°.

  7. Analysis of 33 MeV Nitrogen irradiated UHMWPE

    SciTech Connect

    Grosso, Mariela del; Chappa, Veronica; Garcia Bermudez, Gerardo

    2007-10-26

    In this work, we irradiated UHMWPE with 33 MeV Nitrogen ions, at several fluences, to generate surface modifications without affecting the bulk properties. These modifications were quantified by means of wear resistance tests and Fourier transform infrared spectroscopy (FTIR) measurements. Experimental results show an optimum ion fluence value that maximizes UHMWPE wear resistance.

  8. EGRET observations of bursts at MeV energies

    SciTech Connect

    Catelli, J. R.; Schneid, E. J.

    1998-05-16

    We present preliminary results from the analysis of 16 bright bursts that have been observed by the EGRET NaI calorimeter, or TASC. Seven bursts have been imaged in the EGRET spark chamber above 30 MeV, but in most cases the TASC data gives the highest energy spectra available for these bursts. The TASC can obtain spectral and rate information for bursts well outside the field of view of the EGRET spark chambers, and is sensitive in the energy range from 1 to 200 MeV. The spectra for these bursts are mostly consistent with a simple power law with spectral index in the range from 1.7 to 3.7, with several of the brighter bursts showing emission past 100 MeV. No high energy cutoff has been observed. These high energy photons offer important clues to the physical processes involved at the origin of burst emission. For bursts at cosmological distances extremely high bulk Lorentz factors are implied by the presence of MeV and GeV photons which have not been attenuated by pair production with the lower energy photons from the source.

  9. History of the ZGS 500 MeV booster.

    SciTech Connect

    Simpson, J.; Martin; R.; Kustom, R.

    2006-05-09

    The history of the design and construction of the Argonne 500 MeV booster proton synchrotron from 1969 to 1982 is described. This accelerator has since been in steady use for the past 25 years to power the Argonne Intense Pulsed Neutron Source (IPNS).

  10. Measurements of plasma bremsstrahlung and plasma energy density produced by electron cyclotron resonance ion source plasmas

    NASA Astrophysics Data System (ADS)

    Noland, Jonathan David

    2011-12-01

    The goal of this dissertation was to gain an understanding on the relative importance of microwave power, neutral pressure, and magnetic field configuration on the behavior of the hot electrons within an Electron Cyclotron Resonance Ion Source (ECRIS) plasma. This was carried out through measurement of plasma bremsstrahlung with both NaI(Tl) (hv > 30 keV) and CdTe (2 keV < hv < 70 keV) x-ray detectors, and through measurement of the plasma energy density with a diamagnetic loop placed around the plasma chamber. We also examined the anisotropy in x-ray power by simultaneously measuring the x-ray spectra in two orthogonal directions: radially and axially, using NaI(Tl) detectors. We have seen that for a 6.4 GHz ECRIS, both the x-ray power produced by confined electrons and the plasma energy density behave logarithmically with microwave power. The x-ray flux created by electrons lost from the plasma, however, does not saturate. Thus, the small increase in plasma density that occurred at high microwave powers (> 150 W on a 6.4 GHz ECRIS) was accompanied by a large increase in total x-ray power. We suggest that the saturation of x-ray power and plasma energy density was due to rf-induced pitch-angle scattering of the electrons. X-ray power and plasma energy density were also shown to saturate with neutral pressure, and to increase nearly linearly as the gradient of the magnetic field in the resonance zone was decreased. All of these findings were in agreement with the theoretical models describing ECRIS plasmas. We have discussed the use of a diamagnetic loop as a means of exploring various plasma time scales on a relative basis. Specifically, we focused much of our attention on studying how changing ion source parameters, such as microwave power and neutral pressure, would effect the rise and decay of the integrated diamagnetic signal, which can be related to plasma energy density. We showed that increasing microwave power lowers the e-fold times at both the leading

  11. Absolute intensity calibration of flat-field space-resolved extreme ultraviolet spectrometer using radial profiles of visible and extreme ultraviolet bremsstrahlung continuum emitted from high-density plasmas in Large Helical Device

    SciTech Connect

    Dong Chunfeng; Wang Erhui; Morita, Shigeru; Goto, Motoshi

    2011-11-15

    A precise absolute intensity calibration of a flat-field space-resolved extreme ultraviolet (EUV) spectrometer working in wavelength range of 60-400 A is carried out using a new calibration technique based on radial profile measurement of the bremsstrahlung continuum in Large Helical Device. A peaked vertical profile of the EUV bremsstrahlung continuum has been successfully observed in high-density plasmas (n{sub e}{>=} 10{sup 14} cm{sup -3}) with hydrogen ice pellet injection. The absolute calibration can be done by comparing the EUV bremsstrahlung profile with the visible bremsstrahlung profile of which the absolute value has been already calibrated using a standard lamp. The line-integrated profile of measured visible bremsstrahlung continuum is firstly converted into the local emissivity profile by considering a magnetic surface distortion due to the plasma pressure, and the local emissivity profile of EUV bremsstrahlung is secondly calculated by taking into account the electron temperature profile and free-free gaunt factor. The line-integrated profile of the EUV bremsstrahlung continuum is finally calculated from the local emissivity profile in order to compare with measured EUV bremsstrahlung profile. The absolute intensity calibration can be done by comparing measured and calculated EUV bremsstrahlung profiles. The calibration factor is thus obtained as a function of wavelength with excellent accuracy. It is also found in the profile analysis that the grating reflectivity of EUV emissions is constant along the direction perpendicular to the wavelength dispersion. Uncertainties on the calibration factor determined with the present method are discussed including charge-coupled device operation modes.

  12. Tunable nanometer electrode gaps by MeV ion irradiation

    PubMed Central

    Cheang-Wong, J.-C.; Narumi, K.; Schürmann, G. M.; Aziz, M. J.; Golovchenko, J. A.

    2012-01-01

    We report the use of MeV ion-irradiation-induced plastic deformation of amorphous materials to fabricate electrodes with nanometer-sized gaps. Plastic deformation of the amorphous metal Pd80Si20 is induced by 4.64 MeV O2+ ion irradiation, allowing the complete closing of a sub-micrometer gap. We measure the evolving gap size in situ by monitoring the field emission current-voltage (I-V) characteristics between electrodes. The I-V behavior is consistent with Fowler-Nordheim tunneling. We show that using feedback control on this signal permits gap size fabrication with atomic-scale precision. We expect this approach to nanogap fabrication will enable the practical realization of single molecule controlled devices and sensors. PMID:22550357

  13. XRD study of yttria stabilized zirconia irradiated with 7.3 MeV Fe, 10 MeV I, 16 MeV Au, 200 MeV Xe and 2.2 GeV Au ions

    NASA Astrophysics Data System (ADS)

    Nakano, K.; Yoshizaki, H.; Saitoh, Y.; Ishikawa, N.; Iwase, A.

    2016-03-01

    To simulate energetic neutron irradiation effects, yttria-stabilized zirconia (YSZ) which is one of the major materials for electrical corrosion potential sensors (ECP sensors) was irradiated with heavy ions at energies ranging from 7.3 MeV to 2.2 GeV. Ion irradiation effects on the lattice structure were analyzed using the X-ray diffraction (XRD). The increase in lattice constant was induced by the ion irradiation. It was dominated by the elastic collision process and not by the electronic excitation process. The lattice disordering which was observed as a broadening of XRD peaks was also induced by the irradiation especially for 200 MeV Xe ion irradiation. The present result suggests that the expansion and/or the disordering of YSZ lattice induced by energetic neutrons may affect the durability of a joint interface between a metal housing and YSZ membrane for the usage of ECP sensors in nuclear power reactors.

  14. Magnifying lens for 800 MeV proton radiography.

    PubMed

    Merrill, F E; Campos, E; Espinoza, C; Hogan, G; Hollander, B; Lopez, J; Mariam, F G; Morley, D; Morris, C L; Murray, M; Saunders, A; Schwartz, C; Thompson, T N

    2011-10-01

    This article describes the design and performance of a magnifying magnetic-lens system designed, built, and commissioned at the Los Alamos National Laboratory (LANL) for 800 MeV flash proton radiography. The technique of flash proton radiography has been developed at LANL to study material properties under dynamic loading conditions through the analysis of time sequences of proton radiographs. The requirements of this growing experimental program have resulted in the need for improvements in spatial radiographic resolution. To meet these needs, a new magnetic lens system, consisting of four permanent magnet quadrupoles, has been developed. This new lens system was designed to reduce the second order chromatic aberrations, the dominant source of image blur in 800 MeV proton radiography, as well as magnifying the image to reduce the blur contribution from the detector and camera systems. The recently commissioned lens system performed as designed, providing nearly a factor of three improvement in radiographic resolution. PMID:22047305

  15. Magnifying lens for 800 MeV proton radiography

    NASA Astrophysics Data System (ADS)

    Merrill, F. E.; Campos, E.; Espinoza, C.; Hogan, G.; Hollander, B.; Lopez, J.; Mariam, F. G.; Morley, D.; Morris, C. L.; Murray, M.; Saunders, A.; Schwartz, C.; Thompson, T. N.

    2011-10-01

    This article describes the design and performance of a magnifying magnetic-lens system designed, built, and commissioned at the Los Alamos National Laboratory (LANL) for 800 MeV flash proton radiography. The technique of flash proton radiography has been developed at LANL to study material properties under dynamic loading conditions through the analysis of time sequences of proton radiographs. The requirements of this growing experimental program have resulted in the need for improvements in spatial radiographic resolution. To meet these needs, a new magnetic lens system, consisting of four permanent magnet quadrupoles, has been developed. This new lens system was designed to reduce the second order chromatic aberrations, the dominant source of image blur in 800 MeV proton radiography, as well as magnifying the image to reduce the blur contribution from the detector and camera systems. The recently commissioned lens system performed as designed, providing nearly a factor of three improvement in radiographic resolution.

  16. Magnifying lens for 800 MeV proton radiography

    SciTech Connect

    Merrill, F. E.; Campos, E.; Espinoza, C.; Hogan, G.; Hollander, B.; Lopez, J.; Mariam, F. G.; Morley, D.; Morris, C. L.; Murray, M.; Saunders, A.; Schwartz, C.; Thompson, T. N.

    2011-10-15

    This article describes the design and performance of a magnifying magnetic-lens system designed, built, and commissioned at the Los Alamos National Laboratory (LANL) for 800 MeV flash proton radiography. The technique of flash proton radiography has been developed at LANL to study material properties under dynamic loading conditions through the analysis of time sequences of proton radiographs. The requirements of this growing experimental program have resulted in the need for improvements in spatial radiographic resolution. To meet these needs, a new magnetic lens system, consisting of four permanent magnet quadrupoles, has been developed. This new lens system was designed to reduce the second order chromatic aberrations, the dominant source of image blur in 800 MeV proton radiography, as well as magnifying the image to reduce the blur contribution from the detector and camera systems. The recently commissioned lens system performed as designed, providing nearly a factor of three improvement in radiographic resolution.

  17. First Light: MeV Astrophysics from the Moon

    NASA Astrophysics Data System (ADS)

    Miller, Richard S.; Lawrence, David J.

    2016-06-01

    We report evidence of the first astrophysical source detected from the Moon at MeV energies. Our detection of Cygnus X-1 is a validation of a new investigative paradigm in which the lunar environment is intrinsic to the detection approach: the Lunar Occultation Technique (LOT). NASA’s Lunar Prospector mission served as a proxy for a dedicated LOT-based mission. The characteristic signature of temporal modulation, generated by repeated lunar occultations and encoded within acquired gamma-ray data (0.5-9 MeV), is consistent with an unambiguous detection of Cygnus X-1 at 5.4σ significance. Source localization and long-term monitoring capabilities of the LOT are also demonstrated. This “first light” detection verifies the basic tenets of the LOT methodology, reinforces its feasibility as an alternative astronomical detection paradigm for nuclear astrophysics investigations, and is an illustration of the fundamental benefits of the Moon as a platform for science.

  18. 5 MeV Mott Polarimeter Development at Jefferson Lab

    SciTech Connect

    Price, J. S.; Sinclair, C. K.; Cardman, L. S.; Haanskneccht, J.; Mack, D. J.; Piot, P.; Assamagan, K. A.; Grames, J.

    1997-01-01

    Low energy (E{sub k}=100 keV) Mott scattering polarimeters are ill- suited to support operations foreseen for the polarized electron injector at Jefferson Lab. One solution is to measure the polarization at 5 MeV where multiple and plural scattering are unimportant and precision beam monitoring is straightforward. The higher injector beam current offsets the lower cross-sections. Recent improvements in the CEBAF injector polarimeter scattering chamber have improved signal to noise.

  19. MeV neutrinos in double {beta} decay

    SciTech Connect

    Zuber, K.

    1997-08-01

    The effect of Majorana neutrinos in the MeV mass range on the double {beta} decay of various isotopes is studied on pure phenomenological arguments. By using only experimental half-life data, limits on the mixing parameter U{sub eh}{sup 2} of the order 10{sup {minus}7} can be derived. Also the possible achievements of upcoming experiments and some consequences are outlined. {copyright} {ital 1997} {ital The American Physical Society}

  20. RADIATION DAMAGE TO BSCCO-2223 FROM 50 MEV PROTONS

    SciTech Connect

    Zeller, A.F.; Ronningen, R.M.; Godeke, A.; Heilbronn, L.H.; McMahan-Norris, P.; Gupta, R.

    2007-11-27

    The use of HTS materials in high radiation environmentsrequires that the superconducting properties remain constant up to aradiation high dose. BSCCO-2223 samples from two manufacturers wereirradiated with 50 MeV protons at fluences of up to 5 x 1017 protons/cm2.The samples lost approximately 75 percent of their pre-irradiation Ic.This compares with Nb3Sn, which loses about 50 percent at the samedisplacements per atom.

  1. RADIATION DAMAGE TO BSCCO-2223 FROM 50 MEV PROTONS

    SciTech Connect

    Zeller, A.F.; Ronningen, R.M.; Godeke, Arno; Heibronn, L.H; McMahan-Norris, P.; Gupta, R.

    2007-11-01

    The use of HTS materials in high radiation environments requires that the superconducting properties remain constant up to a radiation high dose. BSCCO-2223 samples from two manufacturers were irradiated with 50 MeV protons at fluences of up to 5 x 10{sup 17} protons/cm{sup 2}. The samples lost approximately 75% of their pre-irradiation I{sub c}. This compares with Nb{sub 3}Sn, which loses about 50% at the same displacements per atom.

  2. Fission studies with 140 MeV {alpha} particles

    SciTech Connect

    Buttkewitz, A.; Duhm, H. H.; Strauss, W.; Goldenbaum, F.; Machner, H.

    2009-09-15

    Binary fission induced by 140 MeV {alpha} particles has been measured for {sup nat}Ag, {sup 139}La, {sup 165}Ho, and {sup 197}Au targets. The measured quantities are the total kinetic energies, fragment masses, and fission cross sections. The results are compared with other data and systematics. A minimum of the fission probability in the vicinity Z{sup 2}/A=24 is observed.

  3. Discovery of a 1731-MeV narrow resonance

    NASA Astrophysics Data System (ADS)

    Vladimirsky, V. V.; Grigor'ev, V. K.; Erofeev, I. A.; Erofeeva, O. N.; Zaitsev, A. P.; Katinov, Yu. V.; Lisin, V. I.; Luzin, V. N.; Nozdrachev, V. N.; Sokolovsky, V. V.; Fadeeva, E. A.; Shkurenko, Yu. P.

    2007-10-01

    Results obtained by studying a previously unknown narrow meson of mass about 1731 MeV are presented. This state was found in a system of two K S mesons. The experimental-data set subjected to the present analysis was obtained with a 6-m spectrometer of the Institute of Theoretical and Experimental Physics (ITEP, Moscow). The statistical sample of event of double K S -meson production was accumulated in π- p interactions by using a beam of 40-GeV pions from the U-70 accelerator of the Institute of High Energy Physics (IHEP, Protvino). There are 58 events at the respective maximum, its statistical significance being close to six standard deviations. The parameters of the observed meson are the following; the mass is M = 1731 ± 2.5 MeV, the width is σ = 3.2 ± 2 MeV, and the product of the production cross section and the respective branching ratio is not less than 20 nb. The fact that the observed meson is extremely narrow does not have a satisfactory theoretical explanation.

  4. Femtosecond time-resolved MeV electron diffraction

    SciTech Connect

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; Wu, L.; Cao, J.; Berger, H.; Geck, J.; Kraus, R.; Pjerov, S.; Shen, Y.; Tobey, R. I.; Hill, J. P.; Wang, X. J.

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing the evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.

  5. Femtosecond time-resolved MeV electron diffraction

    DOE PAGESBeta

    Zhu, Pengfei; Zhu, Y.; Hidaka, Y.; Wu, L.; Cao, J.; Berger, H.; Geck, J.; Kraus, R.; Pjerov, S.; Shen, Y.; et al

    2015-06-02

    We report the experimental demonstration of femtosecond electron diffraction using high-brightness MeV electron beams. High-quality, single-shot electron diffraction patterns for both polycrystalline aluminum and single-crystal 1T-TaS2 are obtained utilizing a 5 fC (~3 × 104 electrons) pulse of electrons at 2.8 MeV. The high quality of the electron diffraction patterns confirms that electron beam has a normalized emittance of ~50 nm rad. The transverse and longitudinal coherence length is ~11 and ~2.5 nm, respectively. The timing jitter between the pump laser and probe electron beam was found to be ~100 fs (rms). The temporal resolution is demonstrated by observing themore » evolution of Bragg and superlattice peaks of 1T-TaS2 following an 800 nm optical pump and was found to be 130 fs. Lastly, our results demonstrate the advantages of MeV electrons, including large elastic differential scattering cross-section and access to high-order reflections, and the feasibility of ultimately realizing below 10 fs time-resolved electron diffraction.« less

  6. Optimization of energy window for {sup 90}Y bremsstrahlung SPECT imaging for detection tasks using the ideal observer with model-mismatch

    SciTech Connect

    Rong Xing; Ghaly, Michael; Frey, Eric C.

    2013-06-15

    Purpose: In yttrium-90 ({sup 90}Y) microsphere brachytherapy (radioembolization) of unresectable liver cancer, posttherapy {sup 90}Y bremsstrahlung single photon emission computed tomography (SPECT) has been used to document the distribution of microspheres in the patient and to help predict potential side effects. The energy window used during projection acquisition can have a significant effect on image quality. Thus, using an optimal energy window is desirable. However, there has been great variability in the choice of energy window due to the continuous and broad energy distribution of {sup 90}Y bremsstrahlung photons. The area under the receiver operating characteristic curve (AUC) for the ideal observer (IO) is a widely used figure of merit (FOM) for optimizing the imaging system for detection tasks. The IO implicitly assumes a perfect model of the image formation process. However, for {sup 90}Y bremsstrahlung SPECT there can be substantial model-mismatch (i.e., difference between the actual image formation process and the model of it assumed in reconstruction), and the amount of the model-mismatch depends on the energy window. It is thus important to account for the degradation of the observer performance due to model-mismatch in the optimization of the energy window. The purpose of this paper is to optimize the energy window for {sup 90}Y bremsstrahlung SPECT for a detection task while taking into account the effects of the model-mismatch. Methods: An observer, termed the ideal observer with model-mismatch (IO-MM), has been proposed previously to account for the effects of the model-mismatch on IO performance. In this work, the AUC for the IO-MM was used as the FOM for the optimization. To provide a clinically realistic object model and imaging simulation, the authors used a background-known-statistically and signal-known-statistically task. The background was modeled as multiple compartments in the liver with activity parameters independently following a

  7. Cross sections and analyzing powers of sup 15 N(p,n) sup 15 O at 200 MeV and 494 MeV

    SciTech Connect

    Ciskowski, D.E. )

    1989-11-01

    Differential cross sections and analyzing powers have been measured for the {sup 15}N(p,n){sup 15} O(g.s.) reaction at bombarding energies of 200 MeV and 494 MeV. The 494 MeV data were obtained at the LAMPF Neutron Time-Of-Flight Facility on an 82 m flight path with a resolution of about 2.7 MeV. The 200 MeV data were obtained at IUCF on a 76m flight path with a resolution of about 1.1 MeV. At both energies, the measured analyzing power is small, the magnitude is less than .2 for momentum transfers of less than 1 fm{sup {minus}1}. In contrast, both Relativistic and standard DWIA calculations predict a maximum of A={minus}.7 near q=0.7 fm{sup {minus}1}. 53 refs., 44 figs.

  8. 17O(n,α)14C cross section from 25 meV to approximately 1 MeV

    NASA Astrophysics Data System (ADS)

    Koehler, P. E.; Graff, S. M.

    1991-12-01

    We have measured the 17O(n,α)14C cross section from thermal energy to approximately 1 MeV. A bump in the data near 3 keV could be fitted by a state whose properties are consistent with a known subthreshold J π=1- level at Ex=8.039 MeV. The cause of the 1/v cross section near thermal energy could not be determined although the known 2+ state at 8.213 MeV was found to be too narrow to contribute much to the thermal cross section. Our data are compared to measurements made via the inverse reaction. There are many differences between the two sets of data. The astrophysical reaction rate was calculated from the measured cross section. This reaction plays a role in the nucleosynthesis of heavy elements in nonstandard big-bang models. At big-bang temperatures, the experimental rate was found to be in fair agreement with the rate estimated from the previously known properties of states of 18O in this region. Furthermore, using the available information from experiments, it was estimated that the 17O(n,α)14C rate is approximately a factor of 103-104 times larger than the 17O(n,γ)18O rate at big-bang temperatures. As a result, there may be significant cycling between 14C and 17O resulting in a reduction of heavy-element nucleosynthesis.

  9. Angular distribution of bremsstrahlung produced by electrons with initial energies in the range from 10 to 20 keV incident on thick Ag

    NASA Astrophysics Data System (ADS)

    Gonzales, Daniel; Cavness, Brandon; Williams, Scott

    2012-03-01

    Experimental results are presented comparing the intensities of the thick-target bremsstrahlung produced by electrons with initial energies ranging from 10 to 20 keV incident on Ag, measured at forward angles in the range of 0 to 55 degrees. When the data are corrected for attenuation due to photon absorption within the target, the results indicate that the detected radiation is distributed anisotropically only at photon energies k that are approximately equal to the initial energy of the incident electrons E0. The results of our experiments suggest that, as k/E0->0, the detected radiation essentially becomes isotropic due primarily to the scattering of electrons within the target. Comparison to the theory of Kissel et al. [At. Data Nucl. Data Tables 28, 381 (1983)] suggests that the angular distribution of bremsstrahlung emitted by electrons incident on thick targets is similar to the angular distribution of bremsstrahlung emitted by electrons incident on free-atom targets only when k/E0 1. The experimental data also are in approximate agreement with the angular distribution predictions of the Monte Carlo program PENELOPE.

  10. Measurement of Bremsstrahlung radiation for in vivo monitoring of 14C tracer distribution between fruit and roots of kiwifruit (Actinidia arguta) cuttings.

    PubMed

    Black, Marykate Z; Minchin, Peter E H; Gould, Nick; Patterson, Kevin J; Clearwater, Michael J

    2012-10-01

    In vivo measurements of (14)C tracer distribution have usually involved monitoring the β(-) particles produced as (14)C decays. These particles are only detectable over short distances, limiting the use of this technique to thin plant material. In the present experiments, X-ray detectors were used to monitor the Bremsstrahlung radiation emitted since β(-) particles were absorbed in plant tissues. Bremsstrahlung radiation is detectable through larger tissue depths. The aim of these experiments was to demonstrate the Bremsstrahlung method by monitoring in vivo tracer-labelled photosynthate partitioning in small kiwifruit (Actinidia arguta (Siebold & Zucc.) Planch. ex Miq.) plants in response to root pruning. A source shoot, consisting of four leaves, was pulse labelled with (14)CO(2). Detectors monitored import into a fruit and the root system, and export from a source leaf. Repeat pulse labelling enabled the comparison of pre- and post-treatment observations within an individual plant. Diurnal trends were observed in the distribution of tracer, with leaf export reduced at night. Tracer accumulated in the roots declined after approximately 48 h, which may have resulted from export of (14)C from the roots in carbon skeletons. Cutting off half the roots did not affect tracer distribution to the remaining half. Tracer distribution to the fruit was increased after root pruning, demonstrating the higher competitive strength of the fruit than the roots for carbohydrate supply. Increased partitioning to the fruit following root pruning has also been demonstrated in kiwifruit field trials.

  11. Optical time of flight studies of lithium plasma in double pulse laser ablation: Evidence of inverse Bremsstrahlung absorption

    SciTech Connect

    Sivakumaran, V.; Joshi, H. C.; Singh, R. K.; Kumar, Ajai

    2014-06-15

    The early stage of formation of lithium plasma in a collinear—double pulse laser ablation mode has been studied using optical time of flight (OTOF) spectroscopy as a function of inter-pulse delay time, the distance from the target surface and the fluence of the ablation lasers. The experimental TOF measurements were carried out for lithium neutral (670.8 nm and 610.3 nm), and ionic (548.4 nm and 478.8 nm) lines. These experimental observations have been compared with that for single pulse laser ablation mode. It is found that depending on the fluence and laser pulse shape of the first pre-ablation laser and the second main ablation laser, the plasma plume formation and its characteristic features can be described in terms of plume-plume or laser-plume interaction processes. Moreover, the enhancement in the intensity of Li neutral and ionic lines is observed when the laser-plume interaction is the dominant process. Here, we see the evidence of the role of inverse Bremsstrahlung absorption process in the initial stage of formation of lithium plasma in this case.

  12. MeV proton flux predictions near Saturn's D ring

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Roussos, E.; Kotova, A.; Cooper, J. F.; Mitchell, D. G.; Krupp, N.; Paranicas, C.

    2015-10-01

    Radiation belts of MeV protons have been observed just outward of Saturn's main rings. During the final stages of the mission, the Cassini spacecraft will pass through the gap between the main rings and the planet. Based on how the known radiation belts of Saturn are formed, it is expected that MeV protons will be present in this gap and also bounce through the tenuous D ring right outside the gap. At least one model has suggested that the intensity of MeV protons near the planet could be much larger than in the known belts. We model this inner radiation belt using a technique developed earlier to understand Saturn's known radiation belts. We find that the inner belt is very different from the outer belts in the sense that its intensity is limited by the densities of the D ring and Saturn's upper atmosphere, not by radial diffusion and satellite absorption. The atmospheric density is relatively well constrained by EUV occultations. Based on that we predict an intensity in the gap region that is well below that of the known belts. It is more difficult to do the same for the region magnetically connected to the D ring since its density is poorly constrained. We find that the intensity in this region can be comparable to the known belts. Such intensities pose no hazard to the mission since Cassini would only experience these fluxes on timescales of minutes but might affect scientific measurements by decreasing the signal-to-contamination ratio of instruments.

  13. The 14 MeV Frascati neutron generator

    NASA Astrophysics Data System (ADS)

    Martone, M.; Angelone, M.; Pillon, M.

    1994-09-01

    The 14-MeV Frascati neutron generator (FNG) uses the T(d, n)α fusion reaction to produce 5.0 × 10 11 n/s. In FNG a beam of deuterons is accelerated up to 300 keV by means of a linear electrostatic tube and directed onto a tritiated-titanium target containing 37 × 10 10 Bq of tritium. This paper describes the FNG facility and its auxiliary apparatus as well as the neutron source calibration performed using the associated α-particle method.

  14. Stability Study of ATF 80MeV Injector Linac

    SciTech Connect

    McCormick, Douglas

    2003-06-09

    A beam stability test was carried out at ATF 80 MeV injector linac. The test was performed by taking data of each monitor in pulse to pulse base. A data acquisition system which consists of a PC and a GPIB network was used for the test. In order to analyze the data, ''Correlation Plot'' method is used which is effective to find out some source of the observed beam fluctuation. This paper describes the result of the stability measurement and the comparison between ATF injector and SLC injector.

  15. Polarization observables in deuteron photodisintegration below 360 MeV

    SciTech Connect

    Glister, J.; Ron, G.; Lee, B. W.; Gilman, R.; Sarty, A. J.; Strauch, S.; Higinbotham, D. W.; Piasetzky, E.; Allada, K.; Armstrong, W.; Arrington, J.; Arenhövel, H.; Beck, A.; Benmokhtar, F.; Berman, B. L.; Boeglin, W.; Brash, E.; Camsonne, A.; Calarco, J.; Chen, J. P.; Choi, S.; Chudakov, E.; Coman, L.; Craver, B.; Cusanno, F.; Dumas, J.; Dutta, C.; Feuerbach, R.; Freyberger, A.; Frullani, S.; Garibaldi, F.; Hansen, J. -O.; Holmstrom, T.; Hyde, C. E.; Ibrahim, H.; Ilieva, Y.; de Jager, C. W.; Jiang, X.; Jones, M. K.; Kang, Hyekoo; Kelleher, A.; Khrosinkova, E.; Kuchina, E.; Kumbartzki, G.; LeRose, J. J.; Lindgren, R.; Markowitz, P.; May-Tal Beck, S.; McCullough, E.; Meekins, D.; Meziane, M.; Meziani, Z. -E.; Michaels, R.; Moffit, B.; Norum, B. E.; Oh, Y.; Olson, M.; Paolone, M.; Paschke, K.; Perdrisat, C. F.; Potokar, M.; Pomatsalyuk, R.; Pomerantz, I.; Puckett, A.; Punjabi, V.; Qian, X.; Qiang, Y.; Ransome, R. D.; Reyhan, M.; Roche, J.; Rousseau, Y.; Saha, A.; Sawatzky, B.; Schulte, E.; Schwamb, M.; Shabestari, M.; Shahinyan, A.; Shneor, R.; Širca, S.; Slifer, K.; Solvignon, P.; Song, J.; Sparks, R.; Subedi, R.; Urciuoli, G. M.; Wang, K.; Wojtsekhowski, B.; Yan, X.; Yao, H.; Zhan, X.; Zhu, X.

    2011-02-03

    We performed high precision measurements of induced and transferred recoil proton polarization in d($\\vec{γ}$, $\\vec{p}$)n for photon energies of 277--357 MeV and θcm = 20 ° -- 120 °. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. Moreover, at the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.

  16. Polarization observables in deuteron photodisintegration below 360 MeV

    DOE PAGESBeta

    Glister, J.; Ron, G.; Lee, B. W.; Gilman, R.; Sarty, A. J.; Strauch, S.; Higinbotham, D. W.; Piasetzky, E.; Allada, K.; Armstrong, W.; et al

    2011-02-03

    We performed high precision measurements of induced and transferred recoil proton polarization in d(more » $$\\vec{γ}$$, $$\\vec{p}$$)n for photon energies of 277--357 MeV and θcm = 20 ° -- 120 °. The measurements were motivated by a longstanding discrepancy between meson-baryon model calculations and data at higher energies. Moreover, at the low energies of this experiment, theory continues to fail to reproduce the data, indicating that either something is missing in the calculations and/or there is a problem with the accuracy of the nucleon-nucleon potential being used.« less

  17. First Light: MeV Astrophysics from the Moon

    NASA Astrophysics Data System (ADS)

    Miller, Richard S.; Lawrence, David J.

    2016-06-01

    We report evidence of the first astrophysical source detected from the Moon at MeV energies. Our detection of Cygnus X-1 is a validation of a new investigative paradigm in which the lunar environment is intrinsic to the detection approach: the Lunar Occultation Technique (LOT). NASA’s Lunar Prospector mission served as a proxy for a dedicated LOT-based mission. The characteristic signature of temporal modulation, generated by repeated lunar occultations and encoded within acquired gamma-ray data (0.5–9 MeV), is consistent with an unambiguous detection of Cygnus X-1 at 5.4σ significance. Source localization and long-term monitoring capabilities of the LOT are also demonstrated. This “first light” detection verifies the basic tenets of the LOT methodology, reinforces its feasibility as an alternative astronomical detection paradigm for nuclear astrophysics investigations, and is an illustration of the fundamental benefits of the Moon as a platform for science.

  18. Effects of MeV Ions on PE and PVDC

    SciTech Connect

    Evelyn, A.L.; Ila, D.; Zimmerman, R.L.; Bhat, K.; Poker, D.B.; Hensley, D.K.

    1997-12-31

    We studied the effects of 3.5 and 5.0 MeV alpha bombardment on polyethylene and polyvinylidene chloride both of which have simple chemical structures. Using a thin polymer film stacking technique, we were able to map the effects of the MeV alpha particles in their track. The first layer of the thin polymer film stack experienced most of the effects of the electronic energy deposited and the last layer received most of the effects of the nuclear stopping. Using Raman microprobe analysis and measuring the ratio of the formation of graphene structures (G-line) to the disordered (amorphous) carbon line (D-line), we were able to separate the severed bond effects in the end of the alpha particles` track in the last polymer film layers from the effects of the electronic energy deposited in the first polymer film layers. The results are in agreement with our other measurements of each polymer film using FTIR, RBS and resistance measurements.

  19. MeV Dark Matter and Small Scale Structure

    SciTech Connect

    Hooper, Dan; Kaplinghat, Manoj; Strigari, Louis E.; Zurek, Kathryn M.; /Wisconsin U., Madison

    2007-04-01

    WIMPs with electroweak scale masses (neutralinos, etc.) remain in kinetic equilibrium with other particle species until temperatures approximately in the range of 10 MeV to 1 GeV, leading to the formation of dark matter substructure with masses as small as 10{sup -4} M{sub {circle_dot}} to 10{sup -12} M{sub {circle_dot}}. However, if dark matter consists of particles with MeV scale masses, as motivated by the observation of 511 keV emission from the Galactic Bulge, such particles are naturally expected to remain in kinetic equilibrium with the cosmic neutrino background until considerably later times. This would lead to a strong suppression of small scale structure with masses below about 10{sup 7}M{sub {circle_dot}} to 10{sup 4} M{sub {circle_dot}}. This cutoff scale has important implications for present and future searches for faint Local Group satellite galaxies and for the missing satellites problem.

  20. X-ray FEL with a meV bandwidth

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Shvyd'ko, Yu. V.; Yurkov, M. V.

    2001-12-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL was proposed by Feldhaus et al. (Opt. Commun. 140 (1997) 341) and named "two-stage SASE FEL". The scheme consists of two undulators and an X-ray monochromator located between them. For the Angström wavelength range the monochromator can be realized using Bragg reflections from crystals. We propose a scheme of monochromator with a bandwidth of 20 meV for the 14.4 keV X-ray SASE FEL being developed in the framework of the TESLA linear collider project. The spectral bandwidth of the radiation from the two-stage SASE FEL (20 meV) is determined by the finite duration of the electron pulse. The shot-to-shot fluctuations of energy spectral density are dramatically reduced in comparison with the 100% fluctuations in a SASE FEL. The peak and average brilliance are three orders of magnitude higher than the values which could be reached by a conventional X-ray SASE FEL.

  1. Bremsstrahlung γ-ray generation by electrons from gas jets irradiated by laser pulses for radiographic testing

    NASA Astrophysics Data System (ADS)

    Oishi, Yuji; Nayuki, Takuya; Zhidkov, Alexei; Fujii, Takashi; Nemoto, Koshichi

    2012-07-01

    Electron generation from a gas jet irradiated by low energy femtosecond laser pulses is studied experimentally as a promising source of radiation for radioisotope-free γ-ray imaging systems. The calculated yield of γ-rays in the 0.5-2 MeV range, produced by low-average-power lasers and gas targets, exceeds the yields from solid tape targets up to 60 times. In addition, an effect of quasi-mono energetic electrons on γ-ray imaging is also discussed.

  2. Two charmoniumlike charged axial resonances near 3885 MeV

    NASA Astrophysics Data System (ADS)

    Voloshin, M. B.

    2016-10-01

    It is argued that the charged Zc+(3885 ) resonance, treated as a "molecular" state of charmed D and D* mesons, is likely to consist of two peaks unequally coupled to the D*+D¯0 and D+D¯*0 channels. The peaks should be split in mass by at least approximately 1.5 MeV. This behavior arises from an enhancement of the effect of isospin violation in the masses of the D and D* mesons due to apparent suppression of forces between the mesons depending on the spins of the heavy as well as the light quarks. The suggested double-peak structure can be studied either by direct shape measurement in the channels with heavy mesons, or by isospin-violating transitions from Zc±(3885 ) to the states of charmonium plus a light meson.

  3. The 50 MeV Beam Test Facility at LBL

    SciTech Connect

    Leemans, W.; Behrsing, G.; Kim, K.J.; Krupnick, J.; Matuk, C.; Selph, F.; Chattopadhyay, S.

    1993-05-01

    A new beam line, expected to be built by September 1993, will transport the 50 MeV electron beam from the ALS LINAC into an experimental area to support various R&D activities in the Center for Beam Physics at LBL. A variety of experiments are planned involving the interaction of such a relativistic electron beam with plasmas (plasma focusing), laser beams (generation of femtosecond X-ray pulses) and electromagnetic cavities (Crab cavities etc....). The beam line is designed using the measured emittance and Twiss parameters of the ALS linac. It accommodates the different requirements of the various experiments on the electron beam properties (charge, energy, pulse length) and on the handling of the beam before and after the interaction point. Special attention has also been given to incorporate diagnostics for measuring the beam properties (such as the electron energy, bunch length and charge) needed in the interpretation of the experiments.

  4. Detectors for energies less than 10 MeV

    NASA Technical Reports Server (NTRS)

    1981-01-01

    In the energy domain 100 keV to 10 MeV, both crystal scintillations and semiconductors are widely used for gamma ray detectors in spectrometer systems. These detectors' operation depend on the fact that gamma rays lose energy by ionization in these materials and electrons and holes are produced. In the case of semiconductors, these electrons and holes are collected by an electric field, and they provide an electric signal that is a direct measure of the energy lost by the gamma ray in the material. Scintillation detectors depend on a further conversion of the energy lost in electron hole pair production to the production of photons. A photomultiplier tube measures the intensity of the photon flux, and an electrical pulse proportional to the photon intensity is produced at the photomultiplier output.

  5. Little Boy neutron spectrum below 3 MeV

    SciTech Connect

    Evans, A.E.; Bennett, E.F.; Yule, T.J.

    1984-01-01

    The leakage neutron spectrum from the Little Boy replica has been measured from 12 keV to 3 MeV using a high-resolution /sup 3/He ionization chamber, and from 1 keV to 3 MeV using proton-recoil proportional counters. The /sup 3/He-spectrometer measurements were made at distances of 0.75 and 2.0 m from the active center and at angles of 0/sup 0/, 45/sup 0/, and 90/sup 0/ with respect to the axis of the assembly. Proton-recoil measurments were made at 90/sup 0/ to the assembly axis at distances of 0.75 and 2.0 m, with a shielded measurement made at 2.0 m to estimate background due to scattering. The /sup 3/He spectrometer was calibrated at Los Alamos using monoenergetic /sup 7/Li(p,n)/sup 7/Be neutrons to generate a family of response functions. The proton-recoil counters were calibrated at Argonne by studying the capture of thermal neutrons by nitrogen in the counters, by observation of the 24-keV neutron resonance in iron, and by relating to the known hydrogen content of the counters. The neutron spectrum from Little Boy was found to be highly structured, with peaks corresponding to minima in the iron total neutron cross section. In particular, influence of the 24-keV iron window was evident in both sets of spectra. The measurements provide information for dosimetry calculations and also a valuable intercomparison of neutron spectrometry using the two different detector types. Spectra measured with both detectors are in essential agreement. 8 references, 7 figures, 2 tables.

  6. Shielding measurements for a 230 MeV proton beam

    SciTech Connect

    Siebers, J.V.

    1990-01-01

    Energetic secondary neutrons produced as protons interact with accelerator components and patients dominate the radiation shielding environment for proton radiotherapy facilities. Due to the scarcity of data describing neutron production, attenuation, absorbed dose, and dose equivalent values, these parameters were measured for 230 MeV proton bombardment of stopping length Al, Fe, and Pb targets at emission angles of 0{degree}, 22{degree}, 45{degree}, and 90{degree} in a thick concrete shield. Low pressure tissue-equivalent proportional counters with volumes ranging from 1 cm{sup 3} to 1000 cm{sup 3} were used to obtain microdosimetric spectra from which absorbed dose and radiation quality are deduced. Does equivalent values and attenuation lengths determined at depth in the shield were found to vary sharply with angle, but were found to be independent of target material. Neutron dose and radiation length values are compared with Monte Carlo neutron transport calculations performed using the Los Alamos High Energy Transport Code (LAHET). Calculations used 230 MeV protons incident upon an Fe target in a shielding geometry similar to that used in the experiment. LAHET calculations overestimated measured attenuation values at 0{degree}, 22{degree}, and 45{degree}, yet correctly predicted the attenuation length at 90{degree}. Comparison of the mean radiation quality estimated with the Monte Carlo calculations with measurements suggest that neutron quality factors should be increased by a factor of 1.4. These results are useful for the shielding design of new facilities as well as for testing neutron production and transport calculations.

  7. Pion Induced Pion Production on Oxygen at 280 Mev.

    NASA Astrophysics Data System (ADS)

    Rozon, Francis Martin

    A first coincident measurement of the pion induced pion production reaction cross-section on a complex nucleus (A > 2) has been successfully performed. In particular, the reaction ^{16}O( pi^+,pi^+pi^-) was measured at 280 MeV incident pion energy. The only previous published measures of this reaction on nuclei consisted of a dated measurement done on emulsion nuclei (BBD*69) and did not provide very stringent limits to the nuclear cross section. Single arm experiments have previously been done elsewhere on the proton (BJK*80) and the deuteron (PGM*84). The reaction was measured at TRIUMF using the QQD magnetic spectrometer in coincidence with the CARUZ (RGR88), a total absorption scintillator range telescope. The measured four-fold differential cross sections were extrapolated to the unmeasured portions of the phase-space to extract the total reaction cross-section at 280 MeV, which was found to be sigma_{tot} = 2.250 +/-.350mb . The (pi,2pi ) cross-section is thus observed to provide approximately 40% of the inclusive double charge exchange cross section (Woo84) at this energy. The model of (OV86) is found to explain many of the features of the data, including sigma _{tot}. The present data do not preclude effects due to pion condensate precursor phenomena as proposed by (CE83) but they do not support the existence of a strong effect. The data are also compared to kinematical Monte Carlo simulations of some possible reaction mechanisms and it is found that the presence of an intermediate Delta can aid the explanation of the low energy features of the pi^+ energy spectrum.

  8. Absolute sensitivity calibration of vacuum and extreme ultraviolet spectrometer systems and Z{sub eff} measurement based on bremsstrahlung continuum in HL-2A tokamak

    SciTech Connect

    Zhou Hangyu; Cui Zhengying; Fu Bingzhong; Sun Ping; Gao Yadong; Xu Yuan; Lu Ping; Yang Qingwei; Duan Xuru; Morita, Shigeru; Goto, Motoshi; Dong Chunfeng

    2012-10-15

    A grazing-incidence flat-field extreme ultraviolet (EUV) spectrometer has been newly developed in HL-2A tokamak. Typical spectral lines are observed from intrinsic impurities of carbon, oxygen, iron, and extrinsic impurity of helium in the wavelength range of 20 A-500 A. Bremsstrahlung continuum is measured at different electron densities of HL-2A discharges to calibrate absolute sensitivity of the EUV spectrometer system and to measure effective ionic charge, Z{sub eff}. The sensitivity of a vacuum ultraviolet (VUV) spectrometer system is also absolutely calibrated in overlapped wavelength range of 300 A-500 A by comparing the intensity between VUV and EUV line emissions.

  9. Note: On the wavelength dependence of the intensity calibration factor of extreme ultraviolet spectrometer determined with profile measurement of bremsstrahlung continuum

    SciTech Connect

    Yamaguchi, N.; Morita, S.; Dong, C. F.; Goto, M.; Maezawa, H.; Miyauchi, H.

    2015-06-15

    The absolute calibration factor of extreme ultraviolet spectroscopic instrument which has recently been determined from absolute radiation profile measurement of bremsstrahlung continuum has been investigated by comparing the calculated diffraction efficiency of grating. An overall tendency of the wavelength dependence of the calibration factor from 40 Å to 500 Å can be reproduced by that of the grating efficiency, especially the agreement between the measured calibration factor and the calculated grating efficiency has been found to be fairly good for the wavelength range 200 Å-500 Å.

  10. Three-Dimensional Dosimetric Analysis and Quantitative Bremsstrahlung Spect Imaging for Treatment of Non-Resectable Pancreatic Cancer Using Colloidal PHOSPHORUS-32.

    NASA Astrophysics Data System (ADS)

    Parsai, E. Ishmael

    1995-01-01

    Current methods of calculating absorbed dose in tissue from beta emitting radiopharmaceuticals yield only estimates of the average dose and cannot be used for dose mapping of bremsstrahlung SPECT images. The present work describes a clinically applicable methodology that can be used to determine the 3-D absorbed dose distribution from bremsstrahlung SPECT images for patients undergoing infusional brachytherapy. The radiopharmaceutical used in this study was colloidal P-32; however, other beta emitters can be used with this method. Calibration curves were generated from phantom studies to determine the activity per voxel from the attenuation corrected measured counts per voxel. The cumulative activity at each voxel position was converted to dose (Gy) using a Monte Carlo based P -32 point dose kernel calculation in water. Two-dimensional isodose distributions then were generated and projected on the reconstructed SPECT slices. This technique was further extended to calculate the quantitative dose for the entire volume and iso-surface dose distributions were generated in 3-D from bremsstrahlung SPECT data. In addition, to calculate the dose rate or accumulated dose at any depth from a given activity, a computer program based on the modified Loevinger point function was developed. This program calculates the dose in two ways: (1) through a closed solution for the spherical geometry by integration of the function over small spherical volumes, or (2) by applying the revised parameters of the modified Loevinger function. A practical and clinically feasible technique was developed for 3-D image co-registration between CT and SPECT for direct anatomic confirmation of the correlation between the region of the P-32 activity distribution and the anatomic site of injection. The method provides the correlation of the body contours obtained from bremsstrahlung SPECT data with corresponding contours from CT. A 3-D surface was first generated by mapping the iso-counts in the SPECT

  11. A comparative study of 30MeV boron{sup 4+} and 60MeV oxygen{sup 8+} ion irradiated Si NPN BJTs

    SciTech Connect

    Kumar, M. Vinay Krishnaveni, S.; Yashoda, T.; Dinesh, C. M.; Krishnakumar, K. S.; Jayashree, B.; Ramani

    2015-06-24

    The impact of 30MeV boron{sup 4+} and 60MeV oxygen{sup 8+} ion irradiation on electrical characteristics of 2N3773 Si NPN Bipolar junction transistors (BJTs) is reported in the present study. The transistors were decapped and irradiated at room temperature. Gummel characteristics, DC current gain and Capacitance-voltage (C-V) characteristics were studied before and after irradiation at different fluences. DC current gain has decreased significantly in both boron and oxygen ion irradiation. Also the value of capacitance decreased 3-4 times with increase in fluence. Both 30MeV boron ion and 60MeV oxygen ion induced similar extent of degradation in electrical characteristics of the transistor.

  12. A comparative study of 30MeV boron4+ and 60MeV oxygen8+ ion irradiated Si NPN BJTs

    NASA Astrophysics Data System (ADS)

    Kumar, M. Vinay; Yashoda, T.; Dinesh, C. M.; Krishnakumar, K. S.; Jayashree, B.; Ramani, Krishnaveni, S.

    2015-06-01

    The impact of 30MeV boron4+ and 60MeV oxygen8+ ion irradiation on electrical characteristics of 2N3773 Si NPN Bipolar junction transistors (BJTs) is reported in the present study. The transistors were decapped and irradiated at room temperature. Gummel characteristics, DC current gain and Capacitance-voltage (C-V) characteristics were studied before and after irradiation at different fluences. DC current gain has decreased significantly in both boron and oxygen ion irradiation. Also the value of capacitance decreased 3-4 times with increase in fluence. Both 30MeV boron ion and 60MeV oxygen ion induced similar extent of degradation in electrical characteristics of the transistor.

  13. Effect of 1.33 Mev gamma radiation and 0.5 Mev electrons on the mechanical properties of graphite fiber composites

    NASA Technical Reports Server (NTRS)

    Fornes, R. E.; Memory, J. D.; Naranong, N.

    1982-01-01

    Epoxy/graphite fiber, polyimide/graphite fiber, and polysulfone/graphite fiber composites were exposed to 1.33 Mev gamma irradiation and 0.5 Mev electron bombardment for varying periods of time. The effects of the irradiation treatments on the breaking stress and Young's modulus were studied by a three point bending test. Effects were small; both electron radiation up to 5000 Mrad and gamma radiation up to 350 Mrad resulted in slight increases in both stress and modulus.

  14. Parametric interference effect in nonresonant spontaneous bremsstrahlung of an electron in the field of a nucleus and two pulsed laser waves

    NASA Astrophysics Data System (ADS)

    Lebed', A. A.; Padusenko, E. A.; Roshchupkin, S. P.; Dubov, V. V.

    2016-07-01

    Nonresonant spontaneous bremsstrahlung of an electron scattered by a nucleus in the field of two moderately strong pulsed waves is studied theoretically. The process is studied in detail within the interference kinematic region. This region is determined by scattering of particles in the same plane at predetermined angles, at which stimulated absorption and emission of photons of external pulsed waves by an electron occur in a correlated manner. It is shown that the probability of the partial process with correlated emission (absorption) by an electron of the equal number of photons of the both waves is of an order of the magnitude greater than the corresponding probability in any other scattering kinematics. The cross section of spontaneous bremsstrahlung in two pulsed waves may be two times greater than the cross section of a free-field process after summation over all stimulated processes of correlated emission and absorption. Obtained results may be experimentally verified, for example, by scientific facilities at sources of pulsed laser radiation (SLAC, FAIR, ELI, XCELS).

  15. Little Boy neutron spectrum below 1 MeV

    SciTech Connect

    Evans, A.E.

    1984-01-01

    A high-resolution /sup 3/He ionization chamber of the type development by Cuttler and Shalev was used to study the neutron spectrum from the Little Boy mockup. Measurements were made at distances of 0.75 and 2.0 m and at angles of 0/sup 0/, 45/sup 0/, and 90/sup 0/ with respect to the axis of the assembly, which was operated at power levels from 8.6 to 450 mW. Detector efficiency as a function of energy as well as parameters for correction of pulse-height distributions for proton-recoil and wall effects were determined from a set of response functions for monoenergetic neutrons measured at the Los Alamos 3.75-MeV Van de Graaff Accelerator Facility. Pulse-shape discrimination was used to separate /sup 3/He-recoil pulses from the pulse-height distribution. The spectrum was found to be highly structured, with peaks corresponding to minima in the total neutron cross section of iron. In particular, 15% of the neutrons above the epithermal peak in energy were found to be in the 24-keV iron window. Lesser peaks out to 700 keV are also attributable to filtering action of the weapon's heavy iron casing. Data taken using experimental proton-recoil proportional counters are compared with the high-resolution spectra.

  16. Multipurpose 5-MeV linear induction accelerator

    NASA Astrophysics Data System (ADS)

    Birx, D. L.; Hawkins, S. A.; Poor, S. E.; Reginato, L. L.; Smith, M. W.

    1984-06-01

    Although linear induction accelerators (LIAs) are quite reliable by most standards, they are limited in repeating rate, average power, and reliability because the final stage of energy delivery is based on spark gap performance. In addition, they have a low duty factor of operation. To provide a higher burst rate and greater reliability, new technology was used to develop a magnetic pulse compression scheme that eliminates all spark gaps and exceeds requirements. The magnetic drive system are tailored to drive induction cells from a few kA to over 10 kA at 500 kV, with average beam power levels in the megawatts. This new 5-MeV, 2.5-kA LIA under construction at the Lawrence Livermore National Laboratory (LLNL) will be used for the development of high brightness sources and will provide a test bed for the new technology, which should lead to LIAs that surpass the radio frequency linacs for efficiency and reliability, as well as fit other industrial applications, such as sewage sterilization.

  17. Multipurpose 5-MeV linear induction accelerator

    SciTech Connect

    Birx, D.L.; Hawkins, S.A.; Poor, S.E.; Reginato, L.L. Smith, M.W.

    1984-06-11

    Although linear induction accelerators (LIAs) are quite reliable by most standards, they are limited in repeating rate, average power, and reliability because the final stage of energy delivery is based on spark gap performance. In addition, they have a low duty factor of operation. To provide a higher burst rate and greater reliability, the researchers used new technology to develop a magnetic pulse compression scheme that eliminates all spark gaps and exceeds requirements. The paper describes the scheme. The magnetic drive system can be tailored to drive induction cells from a few kA to over 10 kA at 500 kV, with average beam power levels in the megawatts. This new 5-MeV, 2.5-kA LIA under construction at the Lawrence Livermore National Laboratory (LLNL) will be used for the development of high brightness sources and will provide a test bed for the new technology, which should lead to LIAs that surpass the radio frequency linacs for efficiency and reliability, as well as fit other industrial applications, such as sewage sterilization.

  18. 400 MeV upgrade for the Fermilab linac

    SciTech Connect

    MacLachlan, J.A.

    1989-03-24

    Fermilab has plans for a comprehensive accelerator upgrade to open new possibilities for both the fixed target and collider experimental programs. An early step in this program is to increase the energy of the linac from 200 to 400 MeV by replacing the last four of its nine 201 MHz Alvarez tanks with twenty-eight 805 MHz side-coupled cavity chains operating at about 8 MV/m average axial field. The principal purpose is to reduce the incoherent spacecharge tuneshift at injection into the Booster which currently limits both the brightness of the beam, an important determinant of collider luminosity, and total intensity to produce both the antiprotons for the collider and the beams to fixed target experimental areas. Other consequences of higher Booster injection energy expected to contribute to some degree of higher intensity limits and improved operational characteristics include improved quality of the guide field at injection, reduced frequency swing for the rf systems, and smaller emittance for the injected beam. The linac upgrade project has moved from a 1986 study through a development project including structure models and numerical studies to a full-feature module prototyping starting this year.

  19. 2 MeV linear accelerator for industrial applications

    NASA Astrophysics Data System (ADS)

    Smith, Richard R.; Farrell, Sherman R.

    1997-02-01

    RPC Industries has developed a high average power scanned electron beam linac system for medium energy industrial processing, such as in-line sterilization. The parameters are: electron energy 2 MeV; average beam current 5.0 mA; and scanned width 0.5 meters. The control system features data logging and a Man-Machine Interface system. The accelerator is vertically mounted, the system height above the floor is 3.4 m, and the footprint is 0.9×1.2 meter2. The typical processing cell inside dimensions are 3.0 m by 3.5 m by 4.2 m high with concrete side walls 0.5 m thick above ground level. The equal exit depth dose is 0.73 gm cm-2. Additional topics that will be reported are: throughput, measurements of dose vs depth, dose uniformity across the web, and beam power by calorimeter and magnetic deflection of the beam.

  20. X-ray FEL with a meV bandwidth

    NASA Astrophysics Data System (ADS)

    Saldin, E. L.; Schneidmiller, E. A.; Shvyd'ko, Yu. V.; Yurkov, M. V.

    2001-08-01

    A new design for a single pass X-ray Self-Amplified Spontaneous Emission (SASE) FEL was proposed in [1] and named two-stage SASE FEL. The scheme consists of two undulators and an X-ray monochromator located between them. For the Angström wavelength range the monochromator could be realized using Bragg reflections from crystals. Proposed scheme of monochromator is illustrated for the 14.4 keV X-ray SASE FEL being developed in the framework of the TESLA linear collider project. The spectral bandwidth of the radiation from the two-stage SASE FEL (20 meV) is defined by the finite duration of the electron pulse. The shot-to-shot fluctuations of energy spectral density are dramatically reduced in comparison with the 100% fluctuations in a SASE FEL. The peak and average brilliance are by three orders of magnitude higher than the values which could be reached by a conventional X-ray SASE FEL.

  1. MERLIN - A meV Resolution Beamline at the ALS

    SciTech Connect

    Reininger, Ruben; Bozek, John; Chuang, Y.-D.; Howells, Malcolm; Kelez, Nicholas; Prestemon, Soren; Marks, Steve; Warwick, Tony; Hussain, Zahid; Jozwiak, Chris; Lanzara, Alessandra; Hasan, M. Zahid

    2007-01-19

    An ultra-high resolution beamline is being constructed at the Advanced Light Source (ALS) for the study of low energy excitations in strongly correlated systems with the use of high-resolution inelastic scattering and angle-resolved photoemission. This new beamline, given the acronym Merlin (for meV resolution line), will cover the energy range 10-150 eV. The monochromator has fixed entrance and exit slits and a plane mirror that can illuminate a spherical grating at the required angle of incidence (as in the SX-700 mechanism). The monochromator can be operated in two different modes. In the highest resolution mode, the energy scanning requires translating the monochromator chamber (total travel 1.1 m) as well as rotating the grating and the plane mirror in front of the grating. The resolution in this mode is practically determined by the slits width. In the second mode, the scanning requires rotating the grating and the plane mirror. This mode can be used to scan a few eV without a significant resolution loss. The source for the beamline is a 1.9 m long, 90 mm period quasi periodic EPU. The expected flux at the sample is higher than 1011 photons/s at a resolving power of 5 x 104 in the energy range 16-130 eV. A second set of gratings can be used to obtain higher flux at the expense of resolution.

  2. Emittance measurements in Grumman 1 MeV beamline

    SciTech Connect

    Debiak, T.; Gammel, G.; Melnychuk, S.

    1992-12-01

    The emittance of a 30 keV H{sup {minus}} beam has been measured with an Allison type electrostatic analyser at two positions separated by 85 cm along the Grumman 1 MeV beamline LEBT at low currents (about 4 mA, no Cs{sub 2}O additive in the source) and at higher currents (10-15 mA, with Cs{sub 2}O additive in the source). No emittance growth was observed between the two positions, but, at the higher current level, the emittance was about 60% higher than at the low current level ({Sigma}{sub n},rms = .0045 {pi} cm-mrad vs. 0070 {pi} cm-mrad). Argon was then introduced up to a partial pressure of 4x10{sup {minus}5} torr, and the emittance decreased back to a range corresponding to that found at the lower currents. However, beam noise was observed at the downstream position, and there is evidence for a small amount of emittance growth (<20%) between the two positions.

  3. ETFE polymer bombarded with 1 MeV proton

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; de Almeida, A.; Muntele, I.; Muntele, C.; Delalez, N.; Ila, D.

    2005-12-01

    The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It has high impact resistance and useful mechanical properties. ETFE can be used as components of pumps, valves, tie wraps, and electrical components. It can also be applied in the field of medical physics as intra venous catheters and as radiation dosimeter. When a material is exposed to the ionizing radiation, it suffers damage that depends on the type, energy and intensity of the radiation. In order to determine the radiation damage mechanism, ETFE films were bombarded with 1 MeV protons to the fluence between 1 × 1011 and 1 × 1016 protons/cm2 and the chemical species emitted during the bombardment were measured with residual gas analysis (RGA) and show that HF gas is the entity preferentially emitted. Optical absorption photospectrometry (OAP) and attenuated total reflectometry fourier transform infrared (ATR-FTIR) shows quantitative chemical evidence of the damage. Our results show that damage is detectable at low proton fluence, but damage that can compromise the application in dosimetry occurs only for fluence greater than 1014 protons/cm2.

  4. Elastic scattering of polarised deuterons from 16O at 200, 400 and 700 MeV

    NASA Astrophysics Data System (ADS)

    van Sen, Nguyen; Yanlin, Ye; Arvieux, J.; Gaillard, G.; Bonin, B.; Boudard, A.; Bruge, G.; Lugol, J. C.; Hasegawa, T.; Soga, F.; Antonuk, L. E.; Cameron, J. M.; Lam, S. T.; Neilson, G. C.; Roy, G.; Sheppard, D. M.; Babinet, R.

    1987-03-01

    Angular distributions of cross section, and Ay and Ayy analysing powers were measured for polarised deuteron elastic scattering from 16O at 200, 400 and 700 MeV. The data at 200 MeV bear evidence of the nuclear rainbow phenomenon while those at 400 and 700 MeV are reminiscent of the proton scattering results at equivalent energies. The data were analysed in terms of the optical model. The real central potential shape changes from an attractive Woods-Saxon form at 200 MeV to a wine-bottle-bottom form with a repulsive interior at 700 MeV. The total reaction cross sections deduced display a clear nuclear transparency effect in the present energy domain in agreement with predictions from the Glauber theory optical limit. Comparison with previous results for 40Ca and 58Ni targets is made.

  5. Neutron interrogation of shielded/unshielded uranium by a 4 MeV linac.

    PubMed

    Lakosi, L; Nguyen, C Tam; Serf, E

    2011-09-01

    A non-destructive active assay method was developed for revealing illicit trafficking of uranium. Photoneutrons produced in beryllium or heavy water by bremsstrahlung from a linac induced fission in the samples. Delayed fission neutrons were detected by a neutron collar built up of (3)He counters embedded in polyethylene moderator. High-enriched uranium samples shielded and unshielded by lead up to 14 mm thickness were detected, with a performance practically unaltered. 25 mg (235)U can be revealed in a 1 min interrogation time. PMID:21507663

  6. Neutron interrogation of shielded/unshielded uranium by a 4 MeV linac.

    PubMed

    Lakosi, L; Nguyen, C Tam; Serf, E

    2011-09-01

    A non-destructive active assay method was developed for revealing illicit trafficking of uranium. Photoneutrons produced in beryllium or heavy water by bremsstrahlung from a linac induced fission in the samples. Delayed fission neutrons were detected by a neutron collar built up of (3)He counters embedded in polyethylene moderator. High-enriched uranium samples shielded and unshielded by lead up to 14 mm thickness were detected, with a performance practically unaltered. 25 mg (235)U can be revealed in a 1 min interrogation time.

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

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  8. Angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei

    NASA Astrophysics Data System (ADS)

    Bystritsky, V. M.; Grozdanov, D. N.; Zontikov, A. O.; Kopach, Yu. N.; Rogov, Yu. N.; Ruskov, I. N.; Sadovsky, A. B.; Skoy, V. R.; Barmakov, Yu. N.; Bogolyubov, E. P.; Ryzhkov, V. I.; Yurkov, D. I.

    2016-07-01

    The work is devoted to measuring the angular distribution of 4.43-MeV γ-rays produced in inelastic scattering of 14.1-MeV neutrons by 12C nuclei. A portable ING-27 neutron generator (designed and fabricated at VNIIA, Moscow) with a built-in 64-pixel silicon α-detector was used as a source of tagged neutrons. The γ-rays of characteristic nuclear radiation from 12C were detected with a spectrometric system that consisted of 22 γ-detectors based on NaI(Tl) crystals arranged around the carbon target. The measured angular distribution of 4.43-MeV γ-rays is analyzed and compared with the results of other published experimental works.

  9. The role of medium modifications for neutrino-pair processes from nucleon-nucleon bremsstrahlung. Impact on the protoneutron star deleptonization

    NASA Astrophysics Data System (ADS)

    Fischer, Tobias

    2016-09-01

    In this article the neutrino-pair production from nucleon-nucleon (NN) bremsstrahlung is explored via medium-modifications of the strong interactions at the level of the one-pion exchange approximation. It governs the bulk part of the NN interaction at low densities relevant for the neutrino physics in core-collapse supernova studies. The resulting medium-modified one-pion exchange rate for the neutrino-pair processes is implemented in simulations of core-collapse supernovae in order to study the impact on the neutrino signal emitted from the deleptonization of the nascent proto-neutron star (PNS). Consequences for the nucleosynthesis of heavy elements of the material ejected from the PNS surface are discussed.

  10. Comparisons of exact results for the virtual photon contribution to single hard bremsstrahlung in radiative return for e{sup +}e{sup -} annihilation

    SciTech Connect

    Jadach, S.; Ward, B.F.L.; Yost, S.A.

    2006-04-01

    We compare fully differential exact results for the virtual photon correction to single hard photon bremsstrahlung obtained using independent calculations, both for e{sup +}e{sup -} annihilation at high-energy colliders and for radiative return applications. The results are compared using Monte Carlo evaluations of the matrix elements as well as by direct analytical evaluation of certain critical limits. Special attention is given to the issues of numerical stability and the treatment of finite-mass corrections. It is found that agreement on the order of 10{sup -5} or better is obtained over most of the range of hard photon energies, at CMS energies relevant to both high-energy collisions and radiative return experiments.

  11. Mixed optical Cherenkov-Bremsstrahlung radiation in vicinity of the Cherenkov cone from relativistic heavy ions: Unusual dependence of the angular distribution width on the radiator thickness

    NASA Astrophysics Data System (ADS)

    Rozhkova, E. I.; Pivovarov, Yu. L.

    2016-07-01

    The Cherenkov radiation (ChR) angular distribution is usually described by the Tamm-Frank (TF) theory, which assumes that relativistic charged particle moves uniformly and rectilinearly in the optically transparent radiator. According to the TF theory, the full width at half maximum (FWHM) of the ChR angular distribution inversely depends on the radiator thickness. In the case of relativistic heavy ions (RHI) a slowing-down in the radiator may sufficiently change the angular distribution of optical radiation in vicinity of the Cherenkov cone, since there appears a mixed ChR-Bremsstrahlung radiation. As a result, there occurs a drastic transformation of the FWHM of optical radiation angular distribution in dependence on the radiator thickness: from inversely proportional (TF theory) to the linearly proportional one. In our paper we present the first analysis of this transformation taking account of the gradual velocity decrease of RHI penetrating through a radiator.

  12. A method for energy window optimization for quantitative tasks that includes the effects of model-mismatch on bias: application to Y-90 bremsstrahlung SPECT imaging.

    PubMed

    Rong, Xing; Du, Yong; Frey, Eric C

    2012-06-21

    Quantitative Yttrium-90 ((90)Y) bremsstrahlung single photon emission computed tomography (SPECT) imaging has shown great potential to provide reliable estimates of (90)Y activity distribution for targeted radionuclide therapy dosimetry applications. One factor that potentially affects the reliability of the activity estimates is the choice of the acquisition energy window. In contrast to imaging conventional gamma photon emitters where the acquisition energy windows are usually placed around photopeaks, there has been great variation in the choice of the acquisition energy window for (90)Y imaging due to the continuous and broad energy distribution of the bremsstrahlung photons. In quantitative imaging of conventional gamma photon emitters, previous methods for optimizing the acquisition energy window assumed unbiased estimators and used the variance in the estimates as a figure of merit (FOM). However, for situations, such as (90)Y imaging, where there are errors in the modeling of the image formation process used in the reconstruction there will be bias in the activity estimates. In (90)Y bremsstrahlung imaging this will be especially important due to the high levels of scatter, multiple scatter, and collimator septal penetration and scatter. Thus variance will not be a complete measure of reliability of the estimates and thus is not a complete FOM. To address this, we first aimed to develop a new method to optimize the energy window that accounts for both the bias due to model-mismatch and the variance of the activity estimates. We applied this method to optimize the acquisition energy window for quantitative (90)Y bremsstrahlung SPECT imaging in microsphere brachytherapy. Since absorbed dose is defined as the absorbed energy from the radiation per unit mass of tissues in this new method we proposed a mass-weighted root mean squared error of the volume of interest (VOI) activity estimates as the FOM. To calculate this FOM, two analytical expressions were

  13. 76Se(t,p)78Se reaction at 17 MeV

    NASA Astrophysics Data System (ADS)

    Watson, D. L.; Fortune, H. T.

    1987-02-01

    The 76Se(t,p)78Se reaction has been studied at an incident energy of 17 MeV. Excitation energies for 80 states (or groups of states) up to 6.16 MeV have been measured. Angular distributions have been obtained for 61 of them, below Ex=5.03 MeV. Comparison of the data with distorted-wave Born approximation calculations, using pure configurations for the transfer amplitudes, have enabled the L transfer (and hence Jπ value) to be determined for 58 of these states. Of these assignments, 52 are new.

  14. Elastic neutron scattering at 96 MeV from 12C and 208Pb

    NASA Astrophysics Data System (ADS)

    Klug, J.; Blomgren, J.; Ataç, A.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Nilsson, L.; Pomp, S.; Tippawan, U.; Elmgren, K.; Olsson, N.; Jonsson, O.; Prokofiev, A. V.; Renberg, P.-U.; Nadel-Turonski, P.; Dangtip, S.; Phansuke, P.; Österlund, M.; Le Brun, C.; Lecolley, J. F.; Lecolley, F. R.; Louvel, M.; Marie-Noury, N.; Schweitzer, C.; Eudes, Ph.; Haddad, F.; Lebrun, C.; Koning, A. J.; Bauge, E.; Delaroche, J. P.; Girod, M.; Ledoux, X.; Romain, P.; Madland, D. G.; Amos, K.; Deb, P. K.; Karataglidis, S.; Crespo, R.; Moro, A. M.

    2003-03-01

    A facility for detection of scattered neutrons in the energy interval 50 130 MeV, scattered nucleon detection assembly, has recently been installed at the 20 180 MeV neutron beam line of The Svedberg Laboratory, Uppsala. First results on elastic neutron scattering from 12C and 208Pb at 96 MeV incident neutron energy are presented. This experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. The results are compared with modern optical model predictions.

  15. The reaction proton deuteron yields triton pion at 470 and 590 MeV

    NASA Technical Reports Server (NTRS)

    Dollhopf, W.; Lunke, C.; Perdrisat, C. F.; Roberts, W. K.; Kitching, P.; Olsen, W. C.; Priest, J. R.

    1973-01-01

    The preliminary results from a study of the deuteron (proton, positive pion)triton reaction are reported. The differential cross section for this reaction was measured for a number of center of mass angles from 37 deg to 160 deg at incident proton energies of 470 and 590 MeV. The cross sections measured at 590 MeV agree with predictions made considering a two-nucleon process. The 470 MeV data shows a peak in the backward direction which is not predicted by this mechanism.

  16. Comparison of bactericidal efficiency of 7.5 MeV X-rays, gamma-rays, and 10 MeV e-beams

    NASA Astrophysics Data System (ADS)

    Song, Beom-Seok; Lee, Yunjong; Moon, Byeong-Geum; Go, Seon-Min; Park, Jong-Heum; Kim, Jae-Kyung; Jung, Koo; Kim, Dong-Ho; Ryu, Sang-Ryeol

    2016-08-01

    This study was performed to verify the feasibility of 7.5 MeV X-rays for food pasteurization through a comparison of the bactericidal efficiency with those of other sources for selected bacterial pathogens. No significant differences were observed between the overall bactericidal efficiency for beef-inoculated pathogens based on the uncertainty of the absorbed dose and variations in bacterial counts. This result supported that all three irradiation sources were effective for inactivation of food-borne bacteria and that 7.5 MeV X-rays may be used for food pasteurization.

  17. Design study for a 500 MeV proton synchrotron with CSNS linac as an injector

    NASA Astrophysics Data System (ADS)

    Huang, Liang-Sheng; Ji, Hong-Fei; Wang, Sheng

    2016-09-01

    Using the China Spallation Neutron Source (CSNS) linac as the injector, a 500 MeV proton synchrotron is proposed for multidisciplinary applications, such as biology, material science and proton therapy. The synchrotron will deliver proton beam with energy from 80 MeV to 500 MeV. A compact lattice design has been worked out, and all the important beam dynamics issues have been investigated. The 80 MeV H- beam is stripped and injected into the synchrotron by using multi-turn injection. In order to continuously extraction the proton with small beam loss, an achromatic structure is proposed and a slow extraction method with RF knock-out is adopted and optimized.

  18. Measurement of inner radiation belt electrons with kinetic energy above 1 MeV

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.

    2015-10-01

    Data from the Proton-Electron Telescope on the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX) satellite, taken during 1992-2009, are analyzed for evidence of inner radiation belt electrons with kinetic energy E > 1 MeV. It is found that most of the data from a detector combination with a nominal energy threshold of 1 MeV were, in fact, caused by a chance coincidence response to lower energy electrons or high-energy protons. In particular, there was no detection of inner belt or slot region electrons above 1 MeV following the 2003 Halloween storm injection, though they may have been present. However, by restricting data to a less-stable, low-altitude trapping region, a persistent presence of inner belt electrons in the energy range 1 to 1.6 MeV is demonstrated. Their soft, exponential energy spectra are consistent with extrapolation of lower energy measurements.

  19. Design study for a 500 MeV proton synchrotron with CSNS linac as an injector

    NASA Astrophysics Data System (ADS)

    Huang, Liang-Sheng; Ji, Hong-Fei; Wang, Sheng

    2016-09-01

    Using the China Spallation Neutron Source (CSNS) linac as the injector, a 500 MeV proton synchrotron is proposed for multidisciplinary applications, such as biology, material science and proton therapy. The synchrotron will deliver proton beam with energy from 80 MeV to 500 MeV. A compact lattice design has been worked out, and all the important beam dynamics issues have been investigated. The 80 MeV H‑ beam is stripped and injected into the synchrotron by using multi-turn injection. In order to continuously extraction the proton with small beam loss, an achromatic structure is proposed and a slow extraction method with RF knock-out is adopted and optimized.

  20. Observation of a 1750 MeV narrow meson decaying into ηη

    NASA Astrophysics Data System (ADS)

    Alde, D.; Binon, F.; Bricman, C.; Donskov, S. V.; Gouanère, M.; Inyakin, A. V.; Kachanov, V. A.; Kakauridze, D. B.; Khaustov, G. V.; Knapp, E. A.; Kulik, A. V.; Lagnaux, J. P.; Lednev, A. A.; Mikhailov, Yu. V.; Mouthuy, Th.; Peigneux, J. P.; Prokoshkin, Yu. D.; Rodnov, Yu. V.; Sadovsky, S. A.; Samoilenko, V. D.; Shagin, P. M.; Shtannikov, A. V.; Singovsky, A. V.; Stroot, J. P.; Sugonyaev, V. P.

    1986-12-01

    A narrow meson which decays into ηη is observed in 38 GeV/c π-p collisions at large momentum transfer. The experiment has been performed at the Serpukhov accelerator with the GAMS-2000 spectrometer. The mass of this new meson is (1755 +/- 8) MeV, its width is less than 50 MeV. Its spin-parity is JPC=0++ or less probably 2++.

  1. The alpha optical potential at 1,370 MeV

    NASA Astrophysics Data System (ADS)

    Bauhoff, W.

    1986-06-01

    Data for elastic scattering of alpha particles from12C and Ca-isotopes at 1,370 MeV are analyzed in terms of a phenomenological optical potential. No evidence is found for deviations of the real part from the usual Woods-Saxon shape, as it is the case for proton scattering at corresponding energies. A further increase in nuclear transparency is found compared to 700 MeV.

  2. Measurement and evaluation of selected 14-MeV neutron cross sections for fusion

    SciTech Connect

    Meadows, J.W.; Smith, D.L.; Cox, S.A.

    1985-01-01

    Experimental neutron-activation cross-section data in the vicinity of 14 MeV are evaluated for several reactions of fusion-related interest using a least-squares method. New experimental measurements are performed at 14.7 MeV for all of these considered reactions and for some commonly-used standard reactions as well. Comparison is made between measured and evaluated results.

  3. Measurement of neutron yield by 62 MeV proton beam on a thick beryllium target

    NASA Astrophysics Data System (ADS)

    Osipenko, M.; Ripani, M.; Alba, R.; Ricco, G.; Schillaci, M.; Barbagallo, M.; Boccaccio, P.; Celentano, A.; Colonna, N.; Cosentino, L.; Del Zoppo, A.; Di Pietro, A.; Esposito, J.; Figuera, P.; Finocchiaro, P.; Kostyukov, A.; Maiolino, C.; Santonocito, D.; Scuderi, V.; Viberti, C. M.

    2013-09-01

    The design of a low-power prototype of neutron amplifier recently proposed within the INFN-E project indicated the need for more accurate data on the neutron yield produced by a proton beam with energy of about 70 MeV impinging on a thick beryllium target. Such measurement was performed at the LNS superconducting cyclotron, covering a wide angular range from 0° to 150° and a complete neutron energy interval from thermal to beam energy. Neutrons with energy above 0.5 MeV were measured by liquid scintillators exploiting their time of flight to determine the kinetic energy. For lower energy neutrons, down to thermal energy, a 3He detector was used. The obtained data are in good agreement with previous measurements at 0° using 66 MeV proton beam, covering neutron energies >10 MeV, as well as with measurements at few selected angles using protons of 46, 55 and 113 MeV energy. The present results extend the neutron yield data in the 60-70 MeV beam energy range. A comparison of measured yields to MCNP, FLUKA and Geant4 Monte Carlo simulations was performed.

  4. Measurement of the Am241(n,2n) reaction cross section from 7.6 MeV to 14.5 MeV

    NASA Astrophysics Data System (ADS)

    Tonchev, A. P.; Angell, C. T.; Boswell, M.; Crowell, A. S.; Fallin, B.; Hammond, S.; Howell, C. R.; Hutcheson, A.; Karwowski, H. J.; Kelley, J. H.; Pedroni, R. S.; Tornow, W.; Becker, J. A.; Dashdorj, D.; Kenneally, J.; Macri, R. A.; Stoyer, M. A.; Wu, C. Y.; Bond, E.; Chadwick, M. B.; Fitzpatrick, J.; Kawano, T.; Rundberg, R. S.; Slemmons, A.; Vieira, D. J.; Wilhelmy, J. B.

    2008-05-01

    The (n,2n) cross section of the radioactive isotope Am241 (T1/2=432.6 y) has been measured in the incident neutron energy range from 7.6 to 14.5 MeV in steps of a few MeV using the activation technique. Monoenergetic neutron beams were produced via the H2(d,n)He3 reaction by bombarding a pressurized deuterium gas cell with an energetic deuteron beam at the TUNL 10-MV Van de Graaff accelerator facility. The induced γ-ray activity of Am240 was measured with high-resolution HPGe detectors. The cross section was determined relative to Al, Ni, and Au neutron activation monitor foils, measured in the same geometry. Good agreement is obtained with previous measurements at around 9 and 14 MeV, whereas for a large discrepancy is observed when our data are compared to those reported by Perdikakis near 11 MeV. Very good agreement is found with the END-B/VII evaluation, whereas the JENDL-3.3 evaluation is in fair agreement with our data.

  5. Corrosion under argon irradiation of titanium in the low MeV range: A study coupling AFM and Spectroscopic Ellipsometry

    NASA Astrophysics Data System (ADS)

    Do, Ngoc-Long; Garcia-Caurel, Enric; Bérerd, Nicolas; Moncoffre, Nathalie; Gorse-Pomonti, Dominique

    2014-05-01

    This paper reports on a recent study of the corrosion under argon ion irradiation of titanium in the low MeV range (1-9 MeV), associating AFM and Spectroscopic Ellipsometry. Irradiation with MeV Arn+ (n = 1, 3) ions produces damages on the titanium surface. Large craters form on the oxidized titanium surface whose characteristics vary as a function of the argon energy between 2 and 9 MeV. The superficial oxide grows thicker under irradiation over the same energy range, especially near 3 MeV. It is suggested that collisions cascades play a significant role in the overall damage process.

  6. Complete identification of states in 208Pb below Ex=6.2 MeV

    NASA Astrophysics Data System (ADS)

    Heusler, A.; Jolos, R. V.; Faestermann, T.; Hertenberger, R.; Wirth, H.-F.; von Brentano, P.

    2016-05-01

    The Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium of the Ludwig-Maximilians-Universität München and the Technische Universität München (Garching, Germany), was used to study the 208Pb(p ,p' ) , 206,207,208Pb (d,p), and 208Pb(d ,d' ) reactions. One hundred fifty-one states at Ex<6.20 MeV in 208Pb are identified and spin and parity assigned. Four states are newly identified and new spins and/or parities are assigned to 25 states. Tentative spin assignments are done to five states at 5.90 MeV . Nearly 50 levels below Ex=6.20 MeV listed by the Nuclear Data Sheets as of 2007 are recognized to be nonexistent or doubly placed. The schematic shell model describing one-particle-one-hole configurations without residual interaction is extended by including two-particle-two-hole configurations. The number of configurations thus predicted at Ex<6.20 MeV nearly agrees with the number of states identified. Several states with dominant two-particle-two-hole configurations are identified. New isobaric analog resonances in 209Bi with two-particle-one-hole structure are discovered at Eres=17.6 MeV . The excitation energies of 70 states with unnatural parity at Ex<6.20 MeV are found to agree within about 200 keV with one-particle-one-hole configurations predicted by the extended schematic shell model. In contrast, the excitation energies of about 20 natural parity states are more than 0.5 MeV lower than predicted, demonstrating the residual interaction among the configurations to be much larger for natural parity than for unnatural parity.

  7. Upper limit on the inner radiation belt MeV electron intensity

    PubMed Central

    Li, X; Selesnick, RS; Baker, DN; Jaynes, AN; Kanekal, SG; Schiller, Q; Blum, L; Fennell, J; Blake, JB

    2015-01-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere PMID:26167446

  8. Neutron-induced fission cross sections of 242Pu from 0.3 MeV to 3 MeV

    NASA Astrophysics Data System (ADS)

    Salvador-Castiñeira, P.; Bryś, T.; Eykens, R.; Hambsch, F.-J.; Göök, A.; Moens, A.; Oberstedt, S.; Sibbens, G.; Vanleeuw, D.; Vidali, M.; Pretel, C.

    2015-10-01

    The majority of the next generation of nuclear power plants (GEN-IV) will work in the fast-neutron-energy region, as opposed to present day thermal reactors. This leads to new and more accurate nuclear-data needs for some minor actinides and structural materials. Following those upcoming demands, the Organisation for Economic Cooperation and Development Nuclear Energy Agency performed a sensitivity study. Based on the latter, an improvement in accuracy from the present 20% to 5% is required for the 242Pu(n ,f ) cross section. Within the same project both the 240Pu(n ,f ) cross section and the 242Pu(n ,f ) cross section were measured at the Van de Graaff accelerator of the Joint Research Centre at the Institute for Reference Materials and Measurements, where quasimonoenergetic neutrons were produced in an energy range from 0.3 MeV up to 3 MeV. A twin Frisch-grid ionization chamber has been used in a back-to-back configuration as fission-fragment detector. The 242Pu(n ,f ) cross section has been normalized to three different isotopes: 237Np(n ,f ) , 235U(n ,f ) , and 238U(n ,f ) . A comprehensive study of the corrections applied to the data and the uncertainties associated is given. The results obtained are in agreement with previous experimental data at the threshold region up to 0.8 MeV. The resonance-like structure at 0.8 to 1.1 MeV, visible in the evaluations and in most previous experimental values, was not reproduced with the same intensity in this experiment. For neutron energies higher than 1.1 MeV, the results of this experiment are slightly lower than the Evaluated Nuclear Data File/B-VII.1 evaluation but in agreement with the experiment of Tovesson et al. (2009) as well as Staples and Morley (1998). Finally, for energies above 1.5 MeV, the results show consistency with the present evaluations.

  9. Highly Stripped Ion Sources for MeV Ion Implantation

    SciTech Connect

    Hershcovitch, Ady

    2009-06-30

    Original technical objectives of CRADA number PVI C-03-09 between BNL and Poole Ventura, Inc. (PVI) were to develop an intense, high charge state, ion source for MeV ion implanters. Present day high-energy ion implanters utilize low charge state (usually single charge) ion sources in combination with rf accelerators. Usually, a MV LINAC is used for acceleration of a few rnA. It is desirable to have instead an intense, high charge state ion source on a relatively low energy platform (de acceleration) to generate high-energy ion beams for implantation. This de acceleration of ions will be far more efficient (in energy utilization). The resultant implanter will be smaller in size. It will generate higher quality ion beams (with lower emittance) for fabrication of superior semiconductor products. In addition to energy and cost savings, the implanter will operate at a lower level of health risks associated with ion implantation. An additional aim of the project was to producing a product that can lead to long­ term job creation in Russia and/or in the US. R&D was conducted in two Russian Centers (one in Tomsk and Seversk, the other in Moscow) under the guidance ofPVI personnel and the BNL PI. Multiple approaches were pursued, developed, and tested at various locations with the best candidate for commercialization delivered and tested at on an implanter at the PVI client Axcelis. Technical developments were exciting: record output currents of high charge state phosphorus and antimony were achieved; a Calutron-Bemas ion source with a 70% output of boron ion current (compared to 25% in present state-of-the-art). Record steady state output currents of higher charge state phosphorous and antimony and P ions: P{sup 2+} (8.6 pmA), P{sup 3+} (1.9 pmA), and P{sup 4+} (0.12 pmA) and 16.2, 7.6, 3.3, and 2.2 pmA of Sb{sup 3+} Sb {sup 4 +}, Sb{sup 5+}, and Sb{sup 6+} respectively. Ultimate commercialization goals did not succeed (even though a number of the products like high

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

    SciTech Connect

    Hartemann, F V; Albert, F

    2009-08-24

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

  11. Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High-energy Emission from the Inner 2°×1° of the Galactic Center

    NASA Astrophysics Data System (ADS)

    Yusef-Zadeh, F.; Hewitt, J. W.; Wardle, M.; Tatischeff, V.; Roberts, D. A.; Cotton, W.; Uchiyama, H.; Nobukawa, M.; Tsuru, T. G.; Heinke, C.; Royster, M.

    2013-01-01

    The high-energy activity in the inner few degrees of the Galactic center is traced by diffuse radio, X-ray, and γ-ray emission. The physical relationship between different components of diffuse gas emitting at multiple wavelengths is a focus of this work. We first present radio continuum observations using the Green Bank Telescope and model the nonthermal spectrum in terms of a broken power-law distribution of ~GeV electrons emitting synchrotron radiation. We show that the emission detected by Fermi is primarily due to nonthermal bremsstrahlung produced by the population of synchrotron emitting electrons in the GeV energy range interacting with neutral gas. The extrapolation of the electron population measured from radio data to low and high energies can also explain the origin of Fe I 6.4 keV line and diffuse TeV emission, as observed with Suzaku, XMM-Newton, Chandra, and the H.E.S.S. observatories. The inferred physical quantities from modeling multiwavelength emission in the context of bremsstrahlung emission from the inner ~300 × 120 pc of the Galactic center are constrained to have the cosmic-ray ionization rate ~1-10 × 10-15 s-1, molecular gas heating rate elevating the gas temperature to 75-200 K, fractional ionization of molecular gas 10-6-10-5, large-scale magnetic field 10-20 μG, the density of diffuse and dense molecular gas ~100 and ~103 cm-3 over 300 pc and 50 pc path lengths, and the variability of Fe I Kα 6.4 keV line emission on yearly timescales. Important implications of our study are that GeV electrons emitting in radio can explain the GeV γ-rays detected by Fermi and that the cosmic-ray irradiation model, like the model of the X-ray irradiation triggered by past activity of Sgr A*, can also explain the origin of the variable 6.4 keV emission from Galactic center molecular clouds.

  12. Generation, control, and transport of a 19-MeV, 700-kA pulsed electron beam

    SciTech Connect

    Sanford, T.W.L.; Halbleib, J.A.; Poukey, J.W.; Skogmo, P.J.; Mikkelson, K.A. ); Welch, D.R. ); Mock, R.C. )

    1992-01-01

    We show experimentally and theoretically that the generation of the 13-TW Hermes III electron beam can be accurately monitored, and that the beam can be accurately directed onto a high-Z target to produce a wide variety of bremsstrahlung patterns. This control allows the study of radiation effects induced by gamma rays to be extended into new parameters regimes. Finally, we show that the beam can be stably transported in low-pressure gas cells.

  13. Elastic neutron scattering at 96 MeV from 12 C and 208 Pb

    NASA Astrophysics Data System (ADS)

    Klug, J.; Blomgren, J.; Ataç, A.; Bergenwall, B.; Hildebrand, A.; Johansson, C.; Mermod, P.; Nilsson, L.; Pomp, S.; Tippawan, U.; Elmgren, K.; Olsson, N.; Jonsson, O.; Prokofiev, A. V.; Renberg, P.-U.; Nadel-Turonski, P.; Dangtip, S.; Phansuke, P.; Österlund, M.; Le Brun, C.; Lecolley, J. F.; Lecolley, F. R.; Louvel, M.; Marie-Noury, N.; Schweitzer, C.; Eudes, Ph.; Haddad, F.; Lebrun, C.; Koning, A. J.; Ledoux, X.

    2003-12-01

    A facility for detection of scattered neutrons in the energy interval 50 130 MeV , SCANDAL, has recently been installed at the 20 180 MeV neutron beam line of the The Svedberg Laboratory, Uppsala. Elastic neutron scattering from 12 C and 208 Pb has been studied at 96 MeV in the 10° 70° interval. The achieved energy resolution, 3.7 MeV , is about an order of magnitude better than for any previous experiment above 65 MeV incident energy. The present experiment represents the highest neutron energy where the ground state has been resolved from the first excited state in neutron scattering. A novel method for normalization of the absolute scale of the cross section has been used. The estimated normalization uncertainty, 3% , is unprecedented for a neutron-induced differential cross section measurement on a nuclear target. The results are compared with modern optical model predictions based on phenomenology or microscopic nuclear theory.

  14. Gamma ray lines from solar flares. [with 2.2 MeV line being strongest

    NASA Technical Reports Server (NTRS)

    Ramaty, R.; Lingenfelter, R. E.

    1974-01-01

    The strongest line, both predicted theoretically and detected observationally at 2.2 MeV, is due to neutron capture by protons in the photosphere. The neutrons are produced in nuclear reactions of flare accelerated particles which also positrons and prompt nuclear gamma rays. From the comparison of the observed and calculated intensities of the lines at 4.4 or 6.1 MeV to that of the 2.2 MeV line, it is possible to deduce the spectrum of accelerated nuclei in the flare region; and from the absolute intensities of these lines, it is possible to obtain the total number of accelerated nuclei at the sun. The study of the 2.2 MeV line also gives information on the amount of He-3 in the photosphere. The study of the line at 0.51 MeV resulting from positron annihilation complements the data obtained from the other lines; in addition it gives information on the temperature and density in the annihilation region.

  15. Modification of semiconductor or metal nanoparticle lattices in amorphous alumina by MeV heavy ions

    NASA Astrophysics Data System (ADS)

    Bogdanović Radović, I.; Buljan, M.; Karlušić, M.; Jerčinović, M.; Dražič, G.; Bernstorff, S.; Boettger, R.

    2016-09-01

    In the present work we investigate effects of MeV heavy ions (from 0.4 MeV Xe to 15 MeV Si) on regularly ordered nanoparticle (NP) lattices embedded in amorphous alumina matrix. These nanostructures were produced by self-assembling growth using magnetron-sputtering deposition. From grazing incidence small-angle x-ray scattering measurements we have found that the used MeV heavy ions do not change the NP sizes, shapes or distances among them. However, ions cause a tilt of the entire NP lattice in the direction parallel to the surface. The tilt angle depends on the incident ion energy, type and the applied fluence and a nearly linear increase of the tilt angle with the ion fluence and irradiation angle was found. This way, MeV heavy ion irradiation can be used to design custom-made NP lattices. In addition, grazing incidence small-angle x-ray scattering can be effectively used as a method for the determination of material redistribution/shift caused by the ion hammering effect. For the first time, the deformation yield in amorphous alumina was determined for irradiation performed at the room temperature.

  16. Independent isotopic yields in 25 MeV and 50 MeV proton-induced fission of natU

    NASA Astrophysics Data System (ADS)

    Penttilä, H.; Gorelov, D.; Elomaa, V.-V.; Eronen, T.; Hager, U.; Hakala, J.; Jokinen, A.; Kankainen, A.; Karvonen, P.; Moore, I. D.; Parkkonen, J.; Peräjärvi, K.; Pohjalainen, I.; Rahaman, S.; Rinta-Antila, S.; Rissanen, J.; Rubchenya, V. A.; Saastamoinen, A.; Simutkin, V.; Sonoda, T.; Weber, C.; Voss, A.; Äystö, J.

    2016-04-01

    Independent isotopic yields for elements from Zn to La in the 25 MeV proton-induced fission of {}^{nat}U were determined with the JYFLTRAP facility. In addition, isotopic yields for Zn, Ga, Rb, Sr, Zr, Pd and Xe in the 50 MeV proton-induced fission of {}^{nat}U were measured. The deduced isotopic yield distributions are compared with a Rubchenya model, the GEF model with universal parameters and the semi-empirical Wahl model. Of these, the Rubchenya model gives the best overall agreement with the obtained data. Combining the isotopic yield data with mass yield data to obtain the absolute independent yields was attempted. The result depends on the mass yield distribution.

  17. Limits on the antiproton/proton ratio in the cosmic radiation from 100 MeV to 1580 MeV

    NASA Technical Reports Server (NTRS)

    Salamon, M. H.; Mckee, S.; Musser, J. A.; Tarle, G.; Tomasch, A.

    1990-01-01

    A search for antiprotons (p-bars) in the cosmic radiation with energies below 1580 MeV at the top of the atmosphere was performed using the PBAR balloon-borne magnetic spectrometer. No antiprotons were observed in 124,000 proton events. For the energy interval 100-640 MeV, an upper limit is reported to the p-bar/p ratio of 2.8 x 10 to the -5th at the top of the atmosphere, after correcting for instrumental efficiencies and contributions from secondary particles. No antiproton was observed in the energy interval 640-1580 MeV, which yields an upper limit to the p-bar/p ratio of 6.1 x 10. By combining both data sets, the limits on the p-bar/p ratio can be improved to 2.0 x 10 to the -5th. The detector performance and instrumental efficiencies of the individual detector components are discussed. A detail Monte Carlo calculation was used to evaluate the instrumental efficiency for both antiprotons and protons as a function of momentum.

  18. Resonance frequency control for the KOMAC 100-MeV drift tube linac

    NASA Astrophysics Data System (ADS)

    Kwon, Hyeok-Jung

    2015-02-01

    A 100-MeV proton accelerator has been developed, and the operation and beam service started at the Korea Multi-purpose Accelerator Complex (KOMAC) in July 2013. The accelerator consists of a 50-keV proton injector, a 3-MeV radio-frequency quadrupole (RFQ) and a 100-MeV drift tube linac (DTL). The resonance frequencies of the DTL tanks are controlled by using the resonance frequency control cooling system (RCCS), installed at every DTL tank. Until now, the RCCS has been operating in the constant temperature mode. If the system is to be stabilized better, the RCCS must be operated in the frequency control mode. For this purpose, studies, including the relation between the resonance frequency and RCCS operation temperature, were done under various conditions. In this paper, the preparations for the frequency control loop of the RCCS are described.

  19. The 500-MeV, 2 1/2% duty factor linear electron accelerator (MEA)

    SciTech Connect

    Bruinsma, P.J.T.; Kroes, F.B.; Kuijer, L.H.; Noomen, J.G.; Spelt, J.B.; Vogel, A.G.C.

    1983-08-01

    Although the intermediate energy electron accelerator in Amsterdam has not reached completely its design specifications, since early 1981 a fully grown scientific program has developed using beams with an energy ranging from 20 to 120 MeV in the 140 MeV substation (for radio-chemistry and low-energy electron scattering over 180/sup 0/) and from 70 to 400 MeV in the high energy stations for electron scattering and physics with pion and muon beams. A brief description of the MIT-type accelerator and its performance will be given with emphasis on typical features of the machine. Some examples will be given of recently obtained scientific data from which can be derived that the quality of the beam is in full accordance with the high performance level of the scientific equipment, involving a complex beam transport system and a pair of spectrometers for high resolution (1x10/sup -4/) work.

  20. Evidence for a 3.8 MeV state in 9Be

    NASA Astrophysics Data System (ADS)

    Smith, R.; Wheldon, C.; Freer, M.; Curtis, N.; Kokalova, Tz.; Almaraz-Calderon, S.; Aprahamian, A.; Ashwood, N. I.; Barr, M.; Bucher, B.; Copp, P.; Couder, M.; Fang, X.; Goldring, G.; Jung, F.; Lesher, S. R.; Lu, W.; Malcolm, J. D.; Roberts, A.; Tan, W. P.; Ziman, V. A.

    2016-07-01

    The breakup reaction 9Be(4He,3 α )n was measured using an array of four double-sided silicon strip detectors at beam energies of 22 and 26 MeV. Excited states in 9Be up to 8 MeV were populated and reconstructed through measurements of the charged reaction products. Evidence is given for a state in 9Be at 3 .82-0.09+0.08 MeV with Γ =1240-90+270 keV. This is consistent with two recent measurements of a state with similar properties in the mirror nucleus 9B. An analysis of the reduced widths (g.s.8Be channel) of this state along with the proposed mirror state has led to a firm limit of J ≤7 /2 and a tentative assignment of Jπ=1 /2- or 3 /2- .

  1. A proposed diagnostic for time-resolved 14 MeV neutron measurements on TFTR

    SciTech Connect

    Ku, L.P.; Nazikian, R.; Prorvitch, V.

    1990-06-01

    A novel method for time resolved measurements of the 14 MeV neutron flux in an intense 2.5 MeV neutron and {gamma}-ray background has been developed. Discrimination against the background 2.5 MeV neutron and {gamma}-ray flux is achieved by the use of polyethylene and lead shielding. A high detection efficiency of DT neutrons is obtained by the use of large volume plastic scintillators and photomultiplier tube designed for operating in high magnetic field environments. Design computations for a such a detector system on TFTR show that an absolute detection efficiency of {approximately}10{sup {minus}8} counts per DT neutron may be obtained. A source strength of 10{sup 13} DT n/s may readily be detected by this method using both count mode and current mode operation with a resolution of {approximately}10 ms within a statistical accuracy of {approximately}5%. 12 refs., 8 figs., 2 tabs.

  2. Commissioning and first operational experience of the 400 MeV Linac at Fermilab

    SciTech Connect

    Junck, K.; Allen, L.; Kroc, T.; MacLachlan, J.; McCrory, E.; Moretti, A.; Noble, R.; Popovic, M.; Schmidt, C.

    1994-07-01

    Commissioning of the Fermilab High Energy Linac during September and October of 1993 has increased the energy of the H- linac from 200 to 400 MeV. The Linac Upgrade is one portion of the Fermilab Upgrad and is intended to reduce the incoherent space-charge tuneshift at injection into the 8 GeV Booster. To accomplish this increase in energy within the existing enclosure, four 201.25 MHz drift-tube linac tankshave been replaced by seven 805 MHz side-coupled cavity modules to accelerate the beam from 116 MeV to 400 MeV. Each module is driven with a klystron amplifier delivering 10 MW of peak power for 60 {mu}sec with a maximum pulse repetition rate of 15 Hz. Nominal beam current is 35 mA with a pulselength of 40 {mu}sec. Results from commissioning and operational experience during Fermilab Collider Run 1B are presented.

  3. Neutron-induced 2.2 MeV background in gamma ray telescopes

    NASA Technical Reports Server (NTRS)

    Zanrosso, E. M.; Long, J. L.; Zych, A. D.; White, R. S.

    1985-01-01

    Neutron-induced gamma ray production is an important source of background in Compton scatter gamma ray telescopes where organic scintillator material is used. Most important is deuteron formation when atmospheric albedo and locally produced neutrons are thermalized and subsequently absorbed in the hydrogenous material. The resulting 2.2 MeV gamma ray line radiation essentially represents a continuous isotropic source within the scintillator itself. Interestingly, using a scintillator material with a high hydrogen-to-carbon ratio to minimize the scintillator material with a high hydrogen-to-carbon ratio to minimize the neutron-induced 4.4 MeV carbon line favors the np reaction. The full problem of neutron-induced background in Compton scatter telescopes has been previously discussed. Results are presented of observations with the University of California balloon-borne Compton scatter telescope where the 2.2 MeV induced line emission is prominently seen.

  4. MeV ion-beam analysis of optical data storage films

    NASA Technical Reports Server (NTRS)

    Leavitt, J. A.; Mcintyre, L. C., Jr.; Lin, Z.

    1993-01-01

    Our objectives are threefold: (1) to accurately characterize optical data storage films by MeV ion-beam analysis (IBA) for ODSC collaborators; (2) to develop new and/or improved analysis techniques; and (3) to expand the capabilities of the IBA facility itself. Using H-1(+), He-4(+), and N-15(++) ion beams in the 1.5 MeV to 10 MeV energy range from a 5.5 MV Van de Graaff accelerator, film thickness (in atoms/sq cm), stoichiometry, impurity concentration profiles, and crystalline structure were determined by Rutherford backscattering (RBS), high-energy backscattering, channeling, nuclear reaction analysis (NRA) and proton induced X-ray emission (PIXE). Most of these techniques are discussed in detail in the ODSC Annual Report (February 17, 1987), p. 74. The PIXE technique is briefly discussed in the ODSC Annual Report (March 15, 1991), p. 23.

  5. The effect of external magnetic field on the bremsstrahlung nonlinear absorption mechanism in the interaction of high intensity short laser pulse with collisional underdense plasma

    SciTech Connect

    Sedaghat, M.; Ettehadi-Abari, M.; Shokri, B. Ghorbanalilu, M.

    2015-03-15

    Laser absorption in the interaction between ultra-intense femtosecond laser and solid density plasma is studied theoretically here in the intensity range Iλ{sup 2}≃10{sup 14}−10{sup 16}Wcm{sup −2}μm{sup 2}. The collisional effect is found to be significant when the incident laser intensity is less than 10{sup 16}Wcm{sup −2}μm{sup 2}. In the current work, the propagation of a high frequency electromagnetic wave, for underdense collisional plasma in the presence of an external magnetic field is investigated. It is shown that, by considering the effect of the ponderomotive force in collisional magnetized plasmas, the increase of laser pulse intensity leads to steepening of the electron density profile and the electron bunches of plasma makes narrower. Moreover, it is found that the wavelength of electric and magnetic fields oscillations increases by increasing the external magnetic field and the density distribution of electrons also grows in comparison with the unmagnetized collisional plasma. Furthermore, the spatial damping rate of laser energy and the nonlinear bremsstrahlung absorption coefficient are obtained in the collisional regime of magnetized plasma. The other remarkable result is that by increasing the external magnetic field in this case, the absorption coefficient increases strongly.

  6. Correlated electron and X ray measurements of quiet time electron precipitation - A comparative study of bremsstrahlung production and transport in the atmosphere

    NASA Astrophysics Data System (ADS)

    Gaines, E. E.; Imhof, W. L.; Francis, W. E.; Walt, M.; Rosenberg, T. J.

    1986-12-01

    Five cases of X-ray observations from balloons, coordinated with measurements of precipitating electrons, were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica, the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X-ray fluxes (E greater than 25 keV) and moderate trapped electron fluxes (E greater than 68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the less than about 0.5 dB of cosmic noise absorption recorded by the Siple 30-MHz riometer. Bremsstrahlung production and transport in the atmosphere were calculated using the measured electron fluxes, energy spectra, and pitch angle distributions for the source. The X-ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from electrons, E greater than 10 keV, exceeded 0.002 erg/sq cm s. The observed electron fluxes show that a significant continuous electron precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.

  7. Correlated electron and X ray measurements of quiet time electron precipitation: a comparative study of Bremsstrahlung production and transport in the atmosphere

    SciTech Connect

    Gaines, E.E.; Imhof, W.L.; Francis, W.E.; Walt, M.; Rosenberg, T.J.

    1986-12-01

    Five cases of X ray observations from balloons coordinated with measurements of precipitating electrons were obtained during passes of the polar-orbiting satellite P78-1 near Siple, Antarctica (L--4.1), the launch point of the balloons. The observations, made during a geomagnetically quiet period in late December 1980 to early January 1981, showed small enhancements of the X ray fluxes (E>25 keV) and moderate trapped electron fluxes (E>68 keV) with pitch angle distributions extending into the edge of the loss cone sufficient to produce the approx. <0.5 dB of cosmic noise absorption recorded by the Siple 30-MHz riometer. Bremsstrahlung production and transport in the atmosphere were calculated using the measured electron fluxes, energy spectra, and pitch angle distributions for the source. The X ray fluxes and spectra calculated for the balloon altitudes were in good agreement with those measured from the balloons when the total energy deposition from electrons, E>10 keV, exceeded 2 x 10/sup -3/ erg/cm/sup 2/ s. The observed electron fluxes show that a significant continuous electron precipitation occurs at the western edge of the South Atlantic magnetic anomaly even at times of low geomagnetic activity.

  8. RF phase stability in the 100-MeV proton linac operation

    NASA Astrophysics Data System (ADS)

    Seol, Kyung-Tae

    2015-02-01

    The 100-MeV proton linac of the Korea multi-purpose accelerator complex (KOMAC) has been operated to provide a proton beam to users. The 100-MeV linac consists of a 3-MeV radio-frequency quadrupole accelerator (RFQ), four 20-MeV drift-tube linac (DTL) tanks, two medium-energy beam-transmitter (MEBT) tanks, and seven 100-MeV DTL tanks. The requirements of the field stability are within ±1% in RF amplitude and ±1 degree in RF phase. The RF phase stability is influenced by a RF reference line, RF transmission lines, and a RF control system. The RF reference signal is chosen to be a 300-MHz local oscillator (LO) signal, and a rigid copper coaxial line with temperature control was installed for an RF reference distribution. A phase stability of ±0.1 degrees was measured under a temperature change of ±0.1 °C. A digital feedback control system with a field-programmable gate-array (FPGA) module was adopted for a high RF stability. The RF phase was maintained within ±0.1 degrees with a dummy cavity and was within ±0.3 degrees at RFQ operation. In the case of the 20-MeV DTL tanks, one klystron drives 4 tanks, and the input phases of 4 tanks were designed to be in phase. The input phases of 4 tanks were fixed within ±1 degree by adjusting a phase shifter in each waveguide.

  9. Neutron induced fission of U isotopes up to 100 MeV

    SciTech Connect

    Lestone, J.P.; Gavron, A.

    1993-10-01

    We have developed a statistical model description of the neutron induced fission of U isotopes using densities of intrinsic states and spin cut off parameters obtained directly from appropriate Nilsson model single particle levels. The first chance fission cross sections are well reproduced when the rotational contributions to the nuclear level densities are taken into account. In order to fit the U(n,f) cross sections above the threshold of second chance fission, we need to: (1) assume that the triaxial level density enhancement is washed out at an excitation energy of {approximately}7 MeV above the triaxial barriers with a width of {approximately}1 MeV, implying a {gamma} deformation for the first barriers of 10{degree} < {gamma} < 20{degree}; and (2) include pre-equilibrium particle emission in the calculations. Above an incoming neutron kinetic energy of {approximately}17 MeV our statistical model U(n,f) cross sections increasingly overestimate the experimental data when so called ``good`` optical model potentials are used to calculate the compound nucleus formation cross sections. This is not surprising since at these high energies little data exists on the scattering of neutrons to help guide the choice of optical model parameters. A satisfactory reproduction of all the available U(n,f) cross sections above 17 MeV is obtained by a simple scaling of our calculated compound nucleus formation cross sections. This scaling factor falls from 1.0 at 17 MeV to 0.82 at 100 MeV.

  10. Cross sections of the (n ,p ) reaction on the 78Se and 80Se isotopes measured for 13.73 MeV to 14.77 MeV and estimated for 10 MeV to 20 MeV neutron energies

    NASA Astrophysics Data System (ADS)

    Attar, F. M. D.; Dhole, S. D.; Bhoraskar, V. N.

    2014-12-01

    The cross sections of 78Se(n ,p ) 78As and 80Se(n ,p ) 80As reactions were measured at five neutron energies over the range 13.73 MeV to 14.77 MeV using 56Fe and 19F as monitor elements, respectively. The cross sections were also theoretically estimated using EMPIRE-II and TALYS codes over 10 MeV to 20 MeV neutrons and matched with the experimental cross sections by making proper choice of the model parameters. The theoretical and experimental cross sections of 80Se(n ,p ) 80As reaction are smaller as compared to the 78Se(n ,p ) 78As reaction at each neutron energy. This difference is attributed to the competing 80Se(n ,2 n )79Se and 80Se( n ,α )Ge77m reactions, which effectively decrease the cross sections of 80Se(n ,p ) 80As reaction as compared to that of the 78Se(n ,p ) 78As reaction over the neutron energy range used in the present work. The cross sections of 78Se(n ,p ) 78As and 80Se(n ,p ) 80As reactions estimated by the EMPIRE-II code initially increase but later on decrease with neutron energy, respectively, above 16 MeV and 19 MeV, whereas those estimated by the TALYS code continuously increase with neutron energy. The present results indicate that the trends in the variation of cross section with neutron energy depend on the model used in the calculations. The cross sections of the 80Se(n ,p ) 80As reaction at different neutron energies reported in the present work can be added as a new data in the nuclear data library.

  11. Energy monitoring device for 1.5-2.4 MeV electron beams

    NASA Astrophysics Data System (ADS)

    Fuochi, P. G.; Lavalle, M.; Martelli, A.; Kovács, A.; Mehta, K.; Kuntz, F.; Plumeri, S.

    2010-03-01

    An easy-to-use and robust energy monitoring device has been developed for reliable detection of day-to-day small variations in the electron beam energy, a critical parameter for quality control and quality assurance in industrial radiation processing. It has potential for using on-line, thus providing real-time information. Its working principle is based on the measurement of currents, or charges, collected by two aluminium absorbers of specific thicknesses (dependent on the beam energy), insulated from each other and positioned within a faraday cup-style aluminium cage connected to the ground. The device has been extensively tested in the energy range of 4-12 MeV under standard laboratory conditions at Institute of Isotopes and CNR-ISOF using different types of electron accelerators; namely, a TESLA LPR-4 LINAC (3-6 MeV) and a L-band Vickers LINAC (7-12 MeV), respectively. This device has been also tested in high power electron beam radiation processing facilities, one equipped with a 7-MeV LUE-8 linear accelerator used for crosslinking of cables and medical device sterilization, and the other equipped with a 10 MeV Rhodotron TT100 recirculating accelerator used for in-house sterilization of medical devices. In the present work, we have extended the application of this method to still lower energy region, i.e. from 1.5 to 2.4 MeV. Also, we show that such a device is capable of detecting deviation in the beam energy as small as 40 keV.

  12. Attenuation of 10 MeV electron beam energy to achieve low doses does not affect Salmonella spp. inactivation kinetics

    NASA Astrophysics Data System (ADS)

    Hieke, Anne-Sophie Charlotte; Pillai, Suresh D.

    2015-05-01

    The effect of attenuating the energy of a 10 MeV electron beam on Salmonella inactivation kinetics was investigated. No statistically significant differences were observed between the D10 values of either Salmonella 4,[5],12:i:- or a Salmonella cocktail (S. 4,[5],12:i:-, Salmonella Heidelberg, Salmonella Newport, Salmonella Typhimurium, Salmonella) when irradiated with either a non-attenuated 10 MeV eBeam or an attenuated 10 MeV eBeam (~2.9±0.22 MeV). The results show that attenuating the energy of a 10 MeV eBeam to achieve low doses does not affect the inactivation kinetics of Salmonella spp. when compared to direct 10 MeV eBeam irradiation.

  13. Loss of alpha-like MeV fusion products from TFTR

    SciTech Connect

    Zweben, S.J.; Boivin, R.L.; Diesso, M.; Hayes, S.E.; Hendel, H.W.; Park, H.; Strachan, J.D.

    1990-03-01

    A detailed comparison between the observed and expected loss of alpha-like MeV fusion products in TFTR is presented. The D-D fusion products (mainly the 1 MeV triton) were measured with an 2-D imaging scintillation detector. The expected first-orbit loss was calculated with a simple Lorentz orbit code. In almost all cases the measured loss was consistent with the expected first-orbit loss model. Exceptions are noted for small major radius plasmas and during strong MHD activity. 37 refs., 28 figs.

  14. Protactinium neutron-induced fission up to 200 MeV

    NASA Astrophysics Data System (ADS)

    Maslov, V.

    2010-03-01

    The theoretical evaluation of 230-233Pa(n,F) cross sections is based on direct data, 230-234Pa fission probabilities and ratios of fission probabilities in first-chance and emissive fission domains, surrogate for neutroninduced fission. First chance fission cross sections trends of Pa are based on consistent description of 232Th(n,F), 232Th(n,2n) and 238U(n,F), 238U(n,xn) data, supported by the ratio surrogate data by Burke et al., 2006, for the 237U(n,F) reaction. Ratio surrogate data on fission probabilities of 232Th(6 Li,4 He)234Pa and 232 Th(6 Li,d)236U by Nayak et al., 2008, support the predicted 233Pa(n, F) cross section at En=11.5-16.5 MeV. The predicted trends of 230-232Pa(n, F) cross section up to En=20 MeV, are consistent with fissilities of Pa nuclides, extracted by 232Th(p,F) (Isaev et al., 2008) and 232Th(p,3n) (Morgenstern et al., 2008) data analysis. The excitation energy and nucleon composition dependence of the transition from asymmetric to symmetric scission for fission observables of Pa nuclei is defined by analysis of p-induced fission of 232Th at Ep=1-200 MeV. Predominantly symmetric fission in 232Th(p,F) at En( p)=200 MeV as revealed by experimental branching ratios (Dujvestijn et al., 1999) is reproduced. Steep transition from asymmetric to symmetric fission with increase of nucleon incident energy is due to fission of neutron-deficient Pa (A≤229) nuclei. A structure of the potential energy surface (a drop of f f symmetric and asymmetric fission barriers difierence (EfSYM - EfASYM) from ~3.5 MeV to ~1 MeV) of N-deficient Pa nuclides (A≤226) and available phase space at outer fission saddles, are shown to be responsible for the sharp increase with En( p) of the symmetric fission component contribution for 232Th(p,F) and 230-233 Pa(n, F) reactions. That is a strong evidence of emissive fission nature of moderately excited Pa nuclides, reliably quantified only up to En( p)~20(30) MeV. Predicted fission cross section of 232Pa(n,F) coincides

  15. Inelastic scattering of 61 MeV protons by pb-207

    NASA Technical Reports Server (NTRS)

    Owais, M.

    1976-01-01

    Differential cross sections for the excitation of the first four neutron-hole states and the doublet at 2.61 MeV by 61.2 MeV protons were measured. The data are analyzed in terms of both a purely collective model description and a microscopic model supplemented by macroscopic core polarization. A realistic two-body interaction is used and knock-on amplitudes are included. Core polarization is found to be important but represents a relatively smaller contribution than in most nuclei previously studied. A parallel analysis of similar data at lower proton bombarding energies reveals a surprisingly strong energy dependence of the reaction mechanisms.

  16. Interaction of MeV ions and VUV photons with polymers and high molecular hydrocarbons

    NASA Astrophysics Data System (ADS)

    Mahfouz, R. M.; Sauer, M.; Atwa, S. T.; Kaiser, R. I.; Roessler, K.

    1992-03-01

    Organic solids such as polymethylene, polyethylene, polyoxymethylene, aliphatic and cyclic paraffins, naphthalene, anthracene and kerogen were irradiated at 77 K with 10-20 MeV cyclotron ions (p, 3He) and up to 10 eV photons. The products were analysed by quadrupole mass spectrometry (QMS). Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and gas chromatography (GC). Besides radiolytic fragmentation, also synthesis of new and complex compounds was observed as a consequence of hot carbon chemistry. Vacuum ultraviolet (VUV) irradiation proved to be less effective in the buildup of new structures than MeV ions, due to its lower linear energy transfer.

  17. Clarification of the three-body decay of 12C (12.71 MeV).

    PubMed

    Fynbo, H O U; Prezado, Y; Bergmann, U C; Borge, M J G; Dendooven, P; Huang, W X; Huikari, J; Jeppesen, H; Jones, P; Jonson, B; Meister, M; Nyman, G; Riisager, K; Tengblad, O; Vogelius, I S; Wang, Y; Weissman, L; Wilhelmsen Rolander, K; Aystö, J

    2003-08-22

    Using beta decays of a clean source of 12N produced at the IGISOL facility, we have measured the breakup of the 12C (12.71 MeV) state into three alpha particles with a segmented particle detector setup. The high quality of the data permits solving the question of the breakup mechanism of the 12.71 MeV state, a longstanding problem in few-body nuclear physics. Among existing models, a modified sequential model fits the data best, but systematic deviations indicate that a three-body description is needed.

  18. Absolute polarimeter for the proton-beam energy of 200 MeV

    SciTech Connect

    Zelenski, A. N.; Atoian, G.; Bogdanov, A. A.; Nurushev, S. B.; Pylaev, F. S.; Raparia, D.; Runtso, M. F.; Stephenson, E.

    2013-12-15

    A polarimeter is upgraded and tested in a 200-MeV polarized-proton beam at the accelerator-collider facility of the Brookhaven National Laboratory. The polarimeter is based on the elastic polarizedproton scattering on a carbon target at an angle of 16.2°, in which case the analyzing power is close to unity and was measured to a very high degree of precision. It is shown that, in the energy range of 190–205 MeV, the absolute polarization can be measured to a precision better than ±0.5%.

  19. Design of a compact spectrometer for high-flux MeV gamma-ray beams

    SciTech Connect

    Corvan, D. J. Sarri, G.; Zepf, M.

    2014-06-15

    A novel design for a compact gamma-ray spectrometer is presented. The proposed system allows for spectroscopy of high-flux multi-MeV gamma-ray beams with MeV energy resolution in a compact design. In its basic configuration, the spectrometer exploits conversion of gamma-rays into electrons via Compton scattering in a low-Z material. The scattered electron population is then spectrally resolved using a magnetic spectrometer. The detector is shown to be effective for gamma-ray energies between 3 and 20 MeV. The main properties of the spectrometer are confirmed by Monte Carlo simulations.

  20. Experimental evidence of the superfocusing effect for axially channeled MeV protons

    NASA Astrophysics Data System (ADS)

    Motapothula, M.; Petrović, S.; Nešković, N.; Breese, M. B. H.

    2016-08-01

    Sub-Ångström focusing of megaelectronvolt (MeV) ions within axial channels was predicted over 10 years ago, but evidence proved elusive. We present experimental angular distributions of axially channeled MeV protons in a 55-nm-thick (001) silicon membrane through which multiple scattering is negligible. Fine angular structure is in excellent agreement with Monte Carlo simulations based on three interaction potentials, providing indirect evidence of the existence of the superfocusing effect with flux enhancement of around 800 within a focused beam width of ˜20 pm .

  1. Design of a compact spectrometer for high-flux MeV gamma-ray beams.

    PubMed

    Corvan, D J; Sarri, G; Zepf, M

    2014-06-01

    A novel design for a compact gamma-ray spectrometer is presented. The proposed system allows for spectroscopy of high-flux multi-MeV gamma-ray beams with MeV energy resolution in a compact design. In its basic configuration, the spectrometer exploits conversion of gamma-rays into electrons via Compton scattering in a low-Z material. The scattered electron population is then spectrally resolved using a magnetic spectrometer. The detector is shown to be effective for gamma-ray energies between 3 and 20 MeV. The main properties of the spectrometer are confirmed by Monte Carlo simulations.

  2. Neutron-induced charged-particle emission studies below 100 MeV at WNR

    SciTech Connect

    Haight, R.C.; Lee, T.M.; Sterbenz, S.M.

    1994-07-01

    Charged-particles produced by neutron bombardment of selected targets with Z=5 through 53 have been studied for neutron energies from 1 MeV to about 100 MeV using the spallation neutron source at WNR/LAMPF. Particle detection with energy measurement and particle identification is accomplished by two-element {Delta}E-E counters, three-element {Delta}E{sub l}-{Delta}E{sub 2}-E counters or with pulse-shape discrimination using scintillators directly in the neutron beam. The experimental techniques for these measurements are described and comparisons made among the different approaches. This presentation introduces five papers contributed to this conference.

  3. Effect of 100MeV oxygen ion irradiation on silicon NPN power transistor

    NASA Astrophysics Data System (ADS)

    Kumar, M. Vinay; Krishnakumar, K. S.; Dinesh, C. M.; Krishnaveni, S.; Ramani

    2012-06-01

    The radiation response of npn Bipolar junction transistor (BJT) has been examined for 100 MeV O7+ ion. Key electrical properties like Gummel characteristics, dc current gain and capacitance-voltage of 100MeV O7+ ion irradiated transistor were studied before and after irradiation. The device was decapped and the electrical characterizations were performed at room temperature. Base current is observed to be more sensitive than collector current and gain appears to be degraded with ion fluence, also considerable degradation in C-V characteristics is observed and doping concentration is found to be increased along with the increase in ion fluence.

  4. MeV negative ion generation from ultra-intense laser interaction with a water spray

    SciTech Connect

    Ter-Avetisyan, S.; Ramakrishna, B.; Borghesi, M.; Doria, D.; Zepf, M.; Sarri, G.; Ehrentraut, L.; Steinke, S.; Sandner, W.; Schnuerer, M.; Andreev, A.; Nickles, P. V.; Tikhonchuk, V.

    2011-08-01

    MeV negative oxygen ions are obtained from a water spray target irradiated by high intensity (5 x 10{sup 19} W/cm{sup 2}) and ultrashort (50 fs) laser pulses. Generation of negative ions is ascribed to electron-capture processes that the laser-accelerated high-energy positive ion experiences when it interacts with atoms in the spray. This mechanism implies the existence of a large number of MeV neutral oxygen atoms, which is consistent with indirect experimental evidence.

  5. MeV heavy ion microprobe PIXE for the analysis of the materials surface

    NASA Astrophysics Data System (ADS)

    Mokuno, Y.; Horino, Y.; Kinomura, A.; Chayahara, A.; Kiuchi, M.; Fujii, K.; Takai, M.

    1994-03-01

    Micro PIXE analysis using MeV phosphorus microprobes was performed to a surface structure which consists of multilevel aluminum wirings in silicon nitride and these results were compared with those from a proton microprobe. In the case of a 2 MeV phosphorus microprobe, the X-ray production was enhanced near the surface due to the large energy deposition rate or the short projectile range. As a result, the increase in surface sensitivity was clearly shown in PIXE mapping images of aluminum, silicon, and phosphorus.

  6. GRB spectra in the MeV range: hints from INTEGRAL

    SciTech Connect

    Bulik, Tomasz; Denis, Miroslaw; Marcinkowski, Radoslaw; Goldoni, Paolo; Laurent, Philip; Osuch, Lukasz

    2007-07-12

    INTEGRAL detects a large number of gamma-ray bursts outside of its field of view with the SPI ACS. Several of these bursts are also detected by IBIS. We present the results of the spectral analysis using the ISRGI, PICSIT and Compton mode data of several bursts. These bursts show very hard spectra with the high energy index reaching -2 above 1 MeV We show that there is a group of bursts with the peak energy Epeak in the MeV range. We discuss the implications of these findings for GLAST.

  7. Neutron scattering measurements in {sup 197}Au from 850 keV to 2.0 MeV

    SciTech Connect

    O`Connor, M.; Chen, J.; Egan, J.J.

    1995-10-01

    Differential elastic and inelastic neutron scattering cross-sections for low lying levels in {sup 197}Au have been measured for incident neutron energies of 1.0 MeV, 1.5 MeV and 2.0 MeV. In addition, the total neutron cross sections in {sup 197}Au was measured from 850 keV to 1.5 MeV. For both experiments the UML 5.5 MV Van-de-Graaff accelerator with a Mobley post acceleration compression system, produced subnanosecond proton pulses which generated neutrons via the {sup 7}Li(p,n) {sup 7}Be reaction.

  8. Positron-electron decay of 28Si at an excitation energy of 50 MeV

    NASA Astrophysics Data System (ADS)

    Buda, A.; Bacelar, J. C.; Balanda, A.; van der Ploeg, H.; Sujkowski, Z.; van der Woude, A.

    1993-03-01

    The electron-position pair decay of 28Si at 50 MeV excitation produced by the isospin T=0 (α + 24Mg) and the mixed isospin T=0,1 (3He + 25Mg) reactions has been studied using a special designed Positron-Electron pair spectrometer PEPSI.

  9. Flare vs. Shock Acceleration of >100 MeV Protons in Large Solar Particle Events

    NASA Astrophysics Data System (ADS)

    Cliver, Edward W.

    2016-05-01

    Recently several studies have presented correlative evidence for a significant-to-dominant role for a flare-resident process in the acceleration of high-energy protons in large solar particle events. In one of these investigations, a high correlation between >100 MeV proton fluence and 35 GHz radio fluence is obtained by omitting large proton events associated with relatively weak flares; these outlying events are attributed to proton acceleration by shock waves driven by coronal mass ejections (CMEs). We argue that the strong CMEs and associated shocks observed for proton events on the main sequence of the scatter plot are equally likely to accelerate high-energy protons. In addition, we examine ratios of 0.5 MeV electron to >100 MeV proton intensities in large SEP events, associated with both well-connected and poorly-connected solar eruptions, to show that scaled-up versions of the small flares associated with classical impulsive SEP events are not significant accelerators of >100 MeV protons.

  10. Residual Nuclei Production in the reaction {sup 136}Xe+ deuterium at 500 A MeV

    SciTech Connect

    Alcantara-Nunez, J. A.; Benlliure, J.; Perez-Loureiro, D.; Casarejos, E.; Fernandez Ordonez, M.; Pereira, J.; Armbruster, P.; Enqvist, T.; Henzl, V.; Henzlova, D.; Kelic, A.; Pleskac, R.; Ricciardi, M. V.; Schmidt, K.-H.; Schmitt, C.; Yordanov, O.; Audouin, L.; Bernas, M.; Lafriaskh, A.; Stephan, C.

    2010-04-26

    More than six hundred nuclei produced in the fragmentation of {sup 136}Xe projectiles at 500 A MeV on a liquid deuterium target were identified using inverse kinematics at the GSI Fragment Separator (FRS). These data are relevant for understanding of spallation reactions.

  11. Proton irradiation of conventional and lithium solar cells - 11-37 MeV

    NASA Technical Reports Server (NTRS)

    Anspaugh, B. E.; Carter, J. R.

    1974-01-01

    Conventional n/p and lithium solar cells were irradiated with 11- to 37-MeV protons. The energy dependence of the solar cell degradation, calculated from electrical parameters and lifetime measurements, is shown to be very slight. Damage coefficients for the n/p cells are calculated. Annealing characteristics of both the lithium cells and the n/p cells are presented.

  12. Voltage holding study of 1 MeV accelerator for ITER neutral beam injector.

    PubMed

    Taniguchi, M; Kashiwagi, M; Umeda, N; Dairaku, M; Takemoto, J; Tobari, H; Tsuchida, K; Yamanaka, H; Watanabe, K; Kojima, A; Hanada, M; Sakamoto, K; Inoue, T

    2012-02-01

    Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A∕m(2) (346 mA) where the 3 × 5 apertures were used. Measurement of the beam profile revealed that deflection of the H(-) ions was large and a part of the H(-) ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A∕m(2) (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A∕m(2)).

  13. DPA damage analysis for 14-MeV neutrons on PFC materials

    NASA Astrophysics Data System (ADS)

    Kim, Dong-woo; Lee, Bo-young; Ko, Seung-kook; Kim, Hee-soo; Noh, Seung-jung

    2015-06-01

    The dpa (displacement per atom) damage for 14-MeV neutron in a pfc materials was simulated using MCNPX/SPECTER code. The dpa values in the main components of the structural material SS316L, Fe, Cr and Ni, were calculated to analyze the effect of nuclear damage. According to the neutron wall load for ITER design base, a neutron flux of 3.5 × 1013 neutrons/cm2·sec was applied. The simulated dpa values were found to be as 3.0 dpa/fpy for Fe, 2.9 dpa/fpy for Cr and 3.1 dpa/fpy for Ni. For practical experiments, the simulated dpa values due to the irradiation damage of 17-MeV protons were found to be as 0.67 dpa at the peak and 0.05 at the surface for SS316L using by SRIM code at the same fluence. For the 17-MeV proton irradiation, the Bragg peak appears at a 0.64-mm depth. Also, SS316L specimens irradiated by a 17-MeV proton beam with a fluence of 1016 protons/cm2 were analyzed by using transmission electron microscopy.

  14. Properties of 16C(6.11 MeV) and its mirror in 16Ne

    NASA Astrophysics Data System (ADS)

    Fortune, H. T.

    2016-07-01

    From previous data for the reaction 14C(t ,p )16C , I have extracted a width of 32.6(5) keV for the strong state at Ex=6.11 MeV . Here, I examine its likely Jπ and configuration. The predicted width of its mirror in 16Ne is estimated to be about 260 keV.

  15. Deuteron-proton breakup reaction at Ed=7.4 MeV

    NASA Astrophysics Data System (ADS)

    Kröger, H.; Nachabe, A. M.; Slobodrian, R. J.

    1986-04-01

    The reaction d+p-->p+p+n is investigated at Elabd=7.4 MeV. Calculations of the cross section are compared with recent kinematically complete measurements. The Coulomb potential is taken fully into account in the calculations based on the strong approximation of Mo/ller wave operator approach.

  16. Scintillation detector efficiencies for neutrons in the energy region above 20 MeV

    SciTech Connect

    Dickens, J.K.

    1991-01-01

    The computer program SCINFUL (for SCINtillator FUL1 response) is a program designed to provide a calculated complete pulse-height response anticipated for neutrons being detected by either an NE-213 (liquid) scintillator or an NE-110 (solid) scintillator in the shape of a right circular cylinder. The point neutron source may be placed at any location with respect to the detector, even inside of it. The neutron source may be monoenergetic, or Maxwellian distributed, or distributed between chosen lower and upper bounds. The calculational method uses Monte Carlo techniques, and it is relativistically correct. Extensive comparisons with a variety of experimental data have been made. There is generally overall good agreement (less than 10% differences) of results for SCINFUL calculations with measured integral detector efficiencies for the design incident neutron energy range of 0.1 to 80 MeV. Calculations of differential detector responses, i.e. yield versus response pulse height, are generally within about 5% on the average for incident neutron energies between 16 and 50 MeV and for the upper 70% of the response pulse height. For incident neutron energies between 50 and 80 MeV, the calculated shape of the response agrees with measurements, but the calculations tend to underpredict the absolute values of the measured responses. Extension of the program to compute responses for incident neutron energies greater than 80 MeV will require new experimental data on neutron interactions with carbon. 32 refs., 6 figs., 2 tabs.

  17. The 2-MEV Model: Constancy of Adolescent Environmental Values within an 8-Year Time Frame

    ERIC Educational Resources Information Center

    Bogner, F. X.; Johnson, B.; Buxner, S.; Felix, L.

    2015-01-01

    The 2-MEV model is a widely used tool to monitor children's environmental perception by scoring individual values. Although the scale's validity has been confirmed repeatedly and independently as well as the scale is in usage within more than two dozen language units all over the world, longitudinal properties still need clarification. The purpose…

  18. Measurement of the. pi. d. -->. pp reaction at T/sub. pi. / = 65 MeV

    SciTech Connect

    Ottermann, C.R.; Boschitz, E.T.; Gyles, W.; List, W.; Tacik, R.; Mango, S.; Konter, J.A.; van den Brandt, B.; Smith, G.R.

    1986-05-01

    The vector analyzing power iT/sub 11/ has been measured for the ..pi..d..-->..pp reaction at an incident pion energy of 65 MeV, using a vector polarized deuteron target. The data are compared with predictions from coupled channels, Faddeev, and perturbation theory calculations.

  19. Large momentum transfer neutron pickup with the (. pi. /sup +/,p) and (p,d) reactions. [90 and 180 MeV, 800 MeV

    SciTech Connect

    Smith, G.R.

    1980-01-01

    The (p,d) reaction was studied for the first time at 800 MeV on seven targets ranging from /sup 7/Li to /sup 40/Ca. The experimental resolution (approx. 400 keV) attained was sufficient to observe many discrete levels in each of the residual nuclei. A modified version of the one-nucleon model successfully describes the magnitude and angular dependence of almost all of the transitions observed. A specific counter example to the two-nucleon model of the reaction mechanism is suggested. The calculations are also sensitive to the neutron single-particle wave function, in accordance with the expectation that the high-momentum components of this wave function are probed at higher bombarding energies. States that have never been seen before were strongly populated in the high excitation region (up to 25 MeV) of some of the residual nuclei. The relative intensities of the other levels observed suggest that coupled-channels mechanisms play an important role for some of these states. Explicit calculations were performed to confirm this for several examples. The first high-resolution measurements of the (..pi../sup +/,p) reaction were also performed on /sup 6/Li, /sup 7/Li, /sup 12/C, and /sup 13/C at pion bombarding energies on and off the pion-nucleon resonance. Calculations employing a one-nucleon model of the reaction mechanism similar to the model successfully used for the (p,d) reaction are unable to account for transitions in the (..pi../sup +/,p) reaction. It is, however, unclear whether this failure is due to a fundamental inadequacy of the model or improper treatment of details in the calculations. A striking similarity was observed in the spectra of the (..pi../sup +/,p) and 800-MeV (p,d) reactions on the same target; this result implies a similar mechanism for the two reactions. 120 references, 97 figures, 15 tables.

  20. 1000 MeV Proton beam therapy facility at Petersburg Nuclear Physics Institute Synchrocyclotron

    NASA Astrophysics Data System (ADS)

    Abrosimov, N. K.; Gavrikov, Yu A.; Ivanov, E. M.; Karlin, D. L.; Khanzadeev, A. V.; Yalynych, N. N.; Riabov, G. A.; Seliverstov, D. M.; Vinogradov, V. M.

    2006-05-01

    Since 1975 proton beam of PNPI synchrocyclotron with fixed energy of 1000 MeV is used for the stereotaxic proton therapy of different head brain diseases. 1300 patients have been treated during this time. The advantage of high energy beam (1000 MeV) is low scattering of protons in the irradiated tissue. This factor allows to form the dose field with high edge gradients (20%/mm) that is especially important for the irradiation of the intra-cranium targets placed in immediate proximity to the life critical parts of the brain. Fixation of the 6 0mm diameter proton beam at the isodose centre with accuracy of ±1.0 mm, two-dimensional rotation technique of the irradiation provide a very high ratio of the dose in the irradiation zone to the dose at the object's surface equal to 200:1. The absorbed doses are: 120-150 Gy for normal hypophysis, 100-120 Gy for pituitary adenomas and 40-70 Gy for arterio-venous malformation at the rate of absorbed dose up to 50 Gy/min. In the paper the dynamics and the efficiency of 1000 MeV proton therapy treatment of the brain deceases are given. At present time the feasibility study is in progress with the goal to create a proton therapy on Bragg peak by means of the moderation of 1000 MeV proton beam in the absorber down to 200 MeV, energy required for radiotherapy of deep seated tumors.

  1. Acceleration of ampere class H(-) ion beam by MeV accelerator.

    PubMed

    Taniguchi, M; Inoue, T; Umeda, N; Kashiwagi, M; Watanabe, K; Tobari, H; Dairaku, M; Sakamoto, K

    2008-02-01

    The H(-) ion accelerator R&D to realize the international thermonuclear experimental reactor neutral beam is ongoing at Japan Atomic Energy Agency (JAEA). The required performance for the prototype MeV accelerator developed at JAEA is 1 MeV, 500 mA (current density of 200 A/m(2)) H(-) ion beam at the beamlet divergence angle of less than 7 mrad. Up to 2005, 836 keV, 146 A/m(2) H(-) ion beam was successfully accelerated as the highest record of the current density at MeV class energy beams. In the present work, high current negative ion beam acceleration test was performed by increasing the beam extraction apertures from 3 x 3 (9 apertures) to 3 x 5 (15 apertures). By fixing the air leak at the source chamber due to backstream ions as well as the improvement of voltage holding capability by a new fiber reinforced plastic insulator ring, the performance of the MeV accelerator was improved. So far, H(-) ion beam of 320 mA was successfully accelerated up to 796 keV with the beam divergence angle of 5.5 mrad. The accelerated drain current including the electron reaches close to the power supply limit for the MeV test facility. The heat flux by the backstream ion during the above beam acceleration was estimated to be 360 W/cm(2). The Cs leakage to the accelerator during the test campaign (Cs total input of 5.0 g) was 0.26 mg (7.0 microg/cm(2)). This is considered to be the allowable level from the viewpoint of voltage holding. PMID:18315236

  2. Measurement of 181 MeV H- ions stripping cross-sections by carbon stripper foil

    NASA Astrophysics Data System (ADS)

    Saha, P. K.; Yoshimoto, M.; Yamazaki, Y.; Hotchi, H.; Harada, H.; Okabe, K.; Kinsho, M.; Irie, Y.

    2015-03-01

    The stripping cross-sections of 181 MeV H- (negative hydrogen) ions by the carbon stripper foil are measured with good accuracy. The present experiment was carried out at the 3-GeV RCS (Rapid Cycling Synchrotron) of J-PARC (Japan Proton Accelerator Research Complex). The stripping cross-sections for different charge states, also known as electron loss cross-sections of H- ion, are denoted as σ-11, σ-10 and σ01, for both electrons stripping (H- →H+), one-electron stripping (H- →H0) and the 2nd-electron stripping (H0 →H+) proceeding σ-10, respectively. We have established very unique and precise techniques for such measurements so as also to determine a foil stripping efficiency very accurately. The cross-sections σ-11, σ-10 and σ01 are obtained to be (0.002 ± 0.001) ×10-18cm2, (1.580 ± 0.034) ×10-18cm2 and (0.648 ± 0.014) ×10-18cm2, respectively. The presently given cross-sections are newly available experimental results for an incident H- energy below 200 MeV and they are also shown to be consistent with recently proposed energy (1 /β2) scaled cross-sections calculated from the previously measured data at 200 and 800 MeV. The present results have a great importance not only at J-PARC for the upgraded H- beam energy of 400 MeV but also for many new and upgrading similar accelerators, where H- beam energies in most cases are considered to be lower than 200 MeV.

  3. Development of mass spectrometry by high energy focused heavy ion beam: MeV SIMS with 8 MeV Cl7+ beam

    NASA Astrophysics Data System (ADS)

    Jeromel, Luka; Siketić, Zdravko; Ogrinc Potočnik, Nina; Vavpetič, Primož; Rupnik, Zdravko; Bučar, Klemen; Pelicon, Primož

    2014-08-01

    Particle induced X-ray emission (PIXE) at microprobe of Jožef Stefan Institute is used to measure two-dimensional quantitative elemental maps of biological tissue. To improve chemical and biological understanding of the processes in vivo, supplementary information about chemical bonding and/or molecular distributions could be obtained by heavy-ion induced molecular desorption and a corresponding mass spectroscopy with Time-Of-Flight (TOF) mass spectrometer. As the method combines the use of heavy focused ions in MeV energy range and TOF Secondary Ion Mass Spectrometry, it is denoted as MeV SIMS. At Jožef Stefan Institute, we constructed a linear TOF spectrometer and mount it to our multipurpose nuclear microprobe. A beam of 8 MeV 35Cl7+ could be focused to a diameter of better than 3 μm × 3 μm and pulsed by electrostatic deflection at the high-energy side of accelerator. TOF mass spectrometer incorporates an 1 m long drift tube and a double stack microchannel plate (MCP) as a stop detector positioned at the end of the drift path. Secondary ions are focused at MCP using electrostatic cylindrical einzel lens. Time of flight spectra are currently acquired with a single-hit time-to-digital converter. Pulsed ion beam produces a shower of secondary ions that are ejected from positively biased target and accelerated towards MCP. We start our time measurement simultaneously with the start of the beam pulse. Signal of the first ion hitting MCP is used to stop the time measurement. Standard pulses proportional to the time of flight are produced with time to analog converter (TAC) and fed into analog-to-digital converter to obtain a time histogram. To enable efficient detection of desorbed fragments with higher molecular masses, which are of particular interest, we recently implemented a state-of art Field Programmable Gate Array (FPGA)-based multi-hit TOF acquisition. To test the system we used focused 8 MeV 35Cl7+ ion beam with pulse length of 180 ns. Mass resolution

  4. Near-earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    DOE PAGESBeta

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; et al

    2015-08-10

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L~5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ~40 s and a dispersionless injection of electrons up to ~3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front.more » Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.« less

  5. Near-earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    SciTech Connect

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; Li, Xinlin; Malaspina, David; Blake, J. Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L.; Reeves, Geoffrey D.; Funsten, Herbert O.; Spence, Harlan E.; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-10

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeV electron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L~5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ~40 s and a dispersionless injection of electrons up to ~3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt (L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  6. Response of AGATA segmented HPGe detectors to gamma rays up to 15.1 MeV

    NASA Astrophysics Data System (ADS)

    Crespi, F. C. L.; Avigo, R.; Camera, F.; Akkoyun, S.; Ataç, A.; Bazzacco, D.; Bellato, M.; Benzoni, G.; Blasi, N.; Bortolato, D.; Bottoni, S.; Bracco, A.; Brambilla, S.; Bruyneel, B.; Ceruti, S.; Ciemała, M.; Coelli, S.; Eberth, J.; Fanin, C.; Farnea, E.; Gadea, A.; Giaz, A.; Gottardo, A.; Hess, H.; Kmiecik, M.; Leoni, S.; Maj, A.; Mengoni, D.; Michelagnoli, C.; Million, B.; Montanari, D.; Nicolini, R.; Pellegri, L.; Recchia, F.; Reiter, P.; Riboldi, S.; Ur, C. A.; Vandone, V.; Valiente-Dobon, J. J.; Wieland, O.; Wiens, A.; Agata Collaboration

    2013-03-01

    The response of AGATA segmented HPGe detectors to gamma rays in the energy range 2-15 MeV was measured. The 15.1 MeV gamma rays were produced using the reaction d(11B,nγ)12C at Ebeam=19.1 MeV, while gamma rays between 2 and 9 MeV were produced using an Am-Be-Fe radioactive source. The energy resolution and linearity were studied and the energy-to-pulse-height conversion resulted to be linear within 0.05%.Experimental interaction multiplicity distributions are discussed and compared with the results of Geant4 simulations. It is shown that the application of gamma-ray tracking allows a suppression of background radiation caused by n-capture in Ge nuclei. Finally the Doppler correction for the 15.1 MeV gamma line, performed using the position information extracted with Pulse-shape analysis is discussed.

  7. An analysis of 100 MeV F 8+ ion and 50 MeV Li 3+ ion irradiation effects on silicon NPN rf power transistors

    NASA Astrophysics Data System (ADS)

    Pushpa, N.; Praveen, K. C.; Gnana Prakash, A. P.; Prabhakara Rao, Y. P.; Tripati, Ambuj; Revannasiddaiah, D.

    2010-08-01

    The dc characteristics exhibited by NPN power transistors are studied systematically before and after irradiation by 100 MeV F 8+ ions and 50 MeV Li 3+ ions in the dose range of 100 krad to 100 Mrad. The transistor parameters such as excess base current (Δ IB= IBpost- IBpre), dc current gain ( hFE), transconductance ( gm), and collector-saturation current ( ICsat) were studied before and after irradiation. The damage factors ( k) for hFE were calculated for ion irradiated transistors using Messenger-Spratt relation. The base current ( IB) was found to increase significantly after ion irradiation and this in turn decreases the hFE of the transistors. The gm decreases significantly after ion irradiation. Moreover, the output characteristics of irradiated devices also show that the collector current ( IC) in the saturation region ( ICsat) decrease with increase in ion dose. The observed change in these characteristics may be due to the ion induced generation-recombination (G-R) centers in emitter-base (E-B) spacer oxide and the ion induced point defects and their complexes in the transistor structure.

  8. Radiation effects on silicon bipolar transistors caused by 3-10 MeV protons and 20-60 MeV bromine ions

    NASA Astrophysics Data System (ADS)

    Li, Xingji; Geng, Hongbin; Lan, Mujie; Liu, Chaoming; Yang, Dezhuang; He, Shiyu

    2010-03-01

    The current gain degradation in silicon NPN bipolar junction transistors (BJTs) was examined under irradiation with 3-10 MeV protons and 20-60 MeV bromine (Br) ions with various dose levels. To characterize the radiation damage of the NPN BJTs, the ionizing dose D i and displacement dose D d as a function of chip depth in the NPN BJTs were calculated for both the protons and Br ions with different energies. Based on the irradiation testing and calculated results, it is shown that the current gain degradation of NPN BJTs is sensitive to the ratio of D d/( D d+ D i) in the sensitive region given by protons and Br ions. The irradiation particles (protons and Br ions), which give larger D d/( D d+ D i) at a given total dose, would generate more severe damage to the NPN BJTs. The reciprocal of the gain variation as a function of the displacement dose was compared, showing that the Messenger-Spratt equation becomes relevant to describe the experimental data, when the ratio of the D d/( D d+ D i) are larger and the displacement dose are higher than a certain value.

  9. Are positive ion radicals formed in pulse radiolysis of alkylbenzenesulfonates. [7 MeV linear accelerator

    SciTech Connect

    Behar, D. )

    1991-05-30

    Oxidation of alkylbenzenesulfonates by OH radicals proceeds via two routes: 75-85% of the OH radicals react via addition to the benzene ring, while the rest abstract an H atom from the alkyl group. The relative distribution between the two paths of reaction depends on the nature of the alkyl group. No evidence for the formation of cation radicals from OH adducts was found. H radicals add to the benzene ring to form cyclohexadienyl type radicals, but when reacted with isopropylbenzenesulfonate about 15% of the H radicals abstract hydrogen from the alkyl to form the benzyl type radical. The reaction of SO{sub 4}{sup {sm bullet}{minus}} with alkylbenzenesulfonates produces 50-70% OH adducts and the rest are the benzyl type radicals. At high concentrations of solute and persulfate a short-lived precursor to the benzyl radicals has been observed. The precursors observed with p-toluenesulfonate, isopropylbenzenesulfonate, and m-toluenesulfonate decay in a first-order process with the rates 1.4 {times} 10{sup 6}, 9.4 {times} 10{sup 5}, and 2.5 {times} 10{sup 5} s{sup {minus}1}, respectively. The short-lived precursor is identified as an unstable OH adduct to the benzene ring.

  10. The calibration of photographic and spectroscopic films: The response of 2aO film to small dosages of alpha particles from 3/10th's rad to 8 rads at energy levels 153 MeV, 79 MeV and 47 MeV

    NASA Technical Reports Server (NTRS)

    Hammond, E. C., Jr.; Peters, Kevin; Stober, AL

    1984-01-01

    The 2aO film, pre-exposed to a series of neutral density filters which on development under standard conditions will produce the standard H-D curve for that film, were then exposed to Alpha paricles with a dose range of 3/10ths rads to 8 rads while varying the energy of the particles using 153 MeV, 70 MeV, and 47 MeV, respectively. An analysis of the film shows that the 3/10th rad dose produces the lowest optical density changes at 70 MeV and 47 MeV. While the optical density readings for the darker patterns seem to oscillate and decrease when exposed to radiation dosages of 3/10th rads to 8 rads.

  11. {sup {bold 6}}Li(vector)+{sup {bold 12}}C inelastic scattering at 30 and 50 MeV

    SciTech Connect

    Kerr, P.L.; Kemper, K.W.; Green, P.V.; Mohajeri, K.; Myers, E.G.; Schmidt, B.G.; Hnizdo, V.

    1996-09-01

    A complete set of analyzing powers (AP`s), {ital iT}{sub 11}, {ital T}{sub 20}, {ital T}{sub 21}, and {ital T}{sub 22}, for 50 MeV {sup 12}C({sup 6}Li(vector),{sup 6}Li) elastic scattering and inelastic scattering to the {sup 12}C(2{sup +}, 4.44 MeV), {sup 12}C(0{sup +}, 7.65 MeV), and {sup 12}C(3{sup {minus}}, 9.64 MeV) states over the center-of-mass (c.m.) angular range 10{degree}{endash}115{degree} is reported. In addition, cross sections for the excited states 3{sup +}(2.18 MeV), 2{sup +}(4.31 MeV), and 1{sup +}(5.65 MeV) of {sup 6}Li were measured by using the inverse-kinematics reaction {sup 6}Li({sup 12}C,{sup 12}C) at 100 MeV. A combined analysis of the new 50 MeV data and previous 30 MeV data has been carried out using the coupled-channels (CC) code FRESCO. The CC calculations use an optical potential with double-folded (DF) real central, Woods-Saxon imaginary central, and Thomas real spin-orbit (SO) potentials. Calculations include reorientation terms and coupling to the first three excited states of {sup 6}Li and the first two nonzerospin states of {sup 12}C. The {sup 6}Li coupling strengths were fixed by the measured {sup 6}Li excited-state cross sections. The elastic-scattering cross sections and A.P.`s are described well. The need for an explicit SO potential is apparent in the elastic and inelastic-scattering AP`s {ital iT}{sub 11}, more so at 30 MeV than at 50 MeV. The rank-2 AP`s up to 50{degree} c.m. arise mainly from ground-state reorientation effects. The DF potential normalization constant {ital N} approaches unity for the 50 MeV data. At both energies, the {sup 12}C(2{sup +}) cross sections are underestimated at large angles, and the description of the {sup 12}C(3{sup {minus}}) cross sections is poor in detail. The {sup 12}C(3{sup {minus}}) AP`s and the {sup 12}C(2{sup +}) {ital iT}{sub 11} are not reproduced at either energy. {copyright} {ital 1996 The American Physical Society.}

  12. A new 5 MeV-300 kW dynamitron for radiation processing

    NASA Astrophysics Data System (ADS)

    Galloway, R. A.; Lisanti, T. F.; Cleland, M. R.

    2004-09-01

    The high beam power required to deliver reasonably effective levels of X-rays for processing food and medical products has driven the development of a new high-power Dynamitron ® system. For many years, RDI accelerators have been providing up to 200 kW of DC electron beam power at energies up to 5.0 MeV. This new system, designed to operate at 300 kW of beam power at 5.0 MeV, is also capable of producing up to 75 mA of beam current when operating at lower voltages. Achieving this high power level and maintaining the high reliability that Dynamitrons are known for has required new designs offering lower power losses yielding higher efficiency and reducing stress in critical components. Improvements in beam control and optics add to the stability and reliability of the system providing a basis for a highly reliable high-power system.

  13. The response of CR-39 nuclear track detector to 1-9 MeV protons

    SciTech Connect

    Sinenian, N.; Rosenberg, M. J.; Manuel, M.; McDuffee, S. C.; Casey, D. T.; Zylstra, A. B.; Rinderknecht, H. G.; Johnson, M. Gatu; Seguin, F. H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.

    2011-10-28

    The response of CR-39 nuclear track detector (TasTrak®) to protons in the energy range of 0.92-9.28 MeV has been studied. Previous studies of the CR-39 response to protons have been extended by examining the piece-to-piece variability in addition to the effects of etch time and etchant temperature; it is shown that the shape of the CR-39 response curve to protons can vary from piece-to-piece. The effects due to the age of CR-39 have also been studied using 5.5 MeV alpha particles over a 5-year period. Track diameters were found to degrade with the age of the CR-39 itself rather than the age of the tracks, consistent with previous studies utilizing different CR-39 over shorter time periods.

  14. The response of CR-39 nuclear track detector to 1-9 MeV protons

    SciTech Connect

    Sinenian, N.; Rosenberg, M. J.; Manuel, M.; McDuffee, S. C.; Casey, D. T.; Zylstra, A. B.; Rinderknecht, H. G.; Gatu Johnson, M.; Seguin, F. H.; Frenje, J. A.; Li, C. K.; Petrasso, R. D.

    2011-10-15

    The response of CR-39 nuclear track detector (TasTrak) to protons in the energy range of 0.92-9.28 MeV has been studied. Previous studies of the CR-39 response to protons have been extended by examining the piece-to-piece variability in addition to the effects of etch time and etchant temperature; it is shown that the shape of the CR-39 response curve to protons can vary from piece-to-piece. Effects due to the age of CR-39 have also been studied using 5.5 MeV alpha particles over a 5-year period. Track diameters were found to degrade with the age of the CR-39 itself rather than the age of the tracks, consistent with previous studies utilizing different CR-39 over shorter time periods.

  15. Plasma production for the 50 MeV plasma lens experiment at LBL

    SciTech Connect

    Leemans, W.; van der Geer, B.; de Loos, M.; Conde, M.; Govil, R.; Chattopadhyay, S.

    1994-06-01

    The Center for Beam Physics at LBL has constructed a Beam Test Facility (BTF) housing a 50 MeV electron beam transport line, which uses the linac injector from the Advanced Light Source, and a terawatt Ti:Al{sub 2}O{sub 3} laser system. The linac operates at 50 MeV and generates 15 ps long electron bunches containing a charge of up to 2 nC. The measured unnormalized beam emittance is 0.33 mm-mrad. These parameters allow for a comprehensive study of focusing of relativistic electron beams with plasma columns, in both the overdense and underdense regime (adiabatic and tapered lenses). A study of adiabatic and/or tapered lenses requires careful control of plasma density and scale lengths of the plasma. We present experimental results on the production of plasmas through resonant two-photon ionization, with parameters relevant to an upcoming plasma lens experiment.

  16. Probing MeV dark matter at low-energy e+e- colliders.

    PubMed

    Borodatchenkova, Natalia; Choudhury, Debajyoti; Drees, Manuel

    2006-04-14

    It has been suggested that the pair annihilation of dark matter particles chi with mass between 0.5 and 20 MeV into e+e- pairs could be responsible for the excess flux (detected by the INTEGRAL satellite) of 511 keV photons coming from the central region of our Galaxy. The simplest way to achieve the required cross section while respecting existing constraints is to introduce a new vector boson U with mass M(U) below a few hundred MeV. We point out that over most of the allowed parameter space, the process e+e--->U(gamma), followed by the decay of U into either an e+e- pair or an invisible (nu(-)nu or chi(-)chi) channel, should lead to signals detectable by current B-factory experiments. A smaller, but still substantial, region of parameter space can also be probed at the Phi factory DAPhiNE.

  17. Energy loss and straggling of MeV ions through biological samples

    SciTech Connect

    Ma Lei; Wang Yugang; Xue Jianming; Chen Qizhong; Zhang Weiming; Zhang Yanwen

    2007-10-15

    Energy loss and energy straggling of energetic ions through natural dehydrated biological samples were investigated using transmission technique. Biological samples (onion membrane, egg coat, and tomato coat) with different mass thickness were studied, together with Mylar for comparison. The energy loss and energy straggling of MeV H and He ions after penetrating the biological and Mylar samples were measured. The experimental results show that the average energy losses of MeV ions through the biological samples are consistent with SRIM predictions; however, large deviation in energy straggling is observed between the measured results and the SRIM predictions. Taking into account inhomogeneity in mass density and structure of the biological sample, an energy straggling formula is suggested, and the experimental energy straggling values are well predicted by the proposed formula.

  18. Energy loss and straggling of MeV ions through biological samples

    SciTech Connect

    Ma, Lie; Wang, Yugang; Xue, Jianming; Chen, Qizhong; Zhang, Weiming; Zhang, Yanwen

    2007-10-15

    Energy loss and energy straggling of energetic ions through natural dehydrated biological samples were investigated using transmission technique. Biological samples (onion membrane, egg coat and tomato coat) with different mass thickness were studied, together with mylar for comparison, in this work. The energy loss and energy straggling of MeV H and He ions after penetrating from the biological and mylar samples were measured. The experimental results show that the average energy losses of MeV ions through the biological samples are consistent with SRIM predictions, however, large deviation in energy straggling is observed between the measured result and the SRIM predictions. Taking into account inhomogeneity in mass density and structure of the biological sample, an energy straggling formula is suggested, and the experimental energy straggling values are well predicated by the proposed formula.

  19. MeV ion beam interaction with polymer films containing cross-linking agents

    SciTech Connect

    Evelyn, A. L.

    1999-06-10

    Polymer films containing cross linking enhancers were irradiated with MeV alpha particles to determine the effects of MeV ion beam interaction on these materials. The contributed effects from the electronic and nuclear stopping powers were separated by irradiating stacked thin films of polyvinyl chloride (PVC), polystyrene (PS) and polyethersulfone (PES). This layered system allowed most of the effects of the electronic energy deposited to be experienced by the first layers and the last layers to receive most of the effects of the nuclear stopping power. RGA, Raman microprobe analysis, RBS and FTIR measured changes in the chemical structures of the irradiated films. The characterization resolved the effects of the stopping powers on the PVC, PS and PES and the results were compared with those from previously studied polymers that did not contain any cross linking agents.

  20. A study of the effects of MeV alpha particles in PE and PVDC

    SciTech Connect

    Evelyn, A.L.; Ila, D.; Zimmerman, R.L.; Bhat, K.; Poker, D.B.; Hensley, D.K.

    1997-02-01

    We have mapped and studied the effects of MeV alpha-particle bombardment in polyvinylidene chloride (PVDC) and polyethylene (PE). We used 3.5 and 5.0 MeV alpha-particle incident beams and stacked polymer films to separate the contributing effects of the electronic ({var_epsilon}{sub e}) and nuclear ({var_epsilon}{sub n}) stopping powers. The electrical conductance and change in the chemical structures were measured by direct resistivity measurement, Raman microprobe, RBS and FTIR. The results indicate significant differences in the ({var_epsilon}{sub e}) and ({var_epsilon}{sub n}) effects at higher alpha-particle bombardment fluences. {copyright} {ital 1997 American Institute of Physics.}

  1. A new proton fluence model for E greater than 10 MeV

    NASA Technical Reports Server (NTRS)

    Feynman, Joan; Armstrong, T. P.; Dao-Gibner, L.; Silverman, S.

    1988-01-01

    Researchers describe a new engineering model for the fluence of protons with energies greater than 10 MeV. The data set used is a combination of observations made primarily from the Earth's surface between 1956 and 1963 and observations made from spacecraft in the vicinity of Earth between 1963 and 1985. With this data set we find that the distinction between ordinary proton events and anomalously large proton events made in earlier work disappears. The greater than 10 MeV fluences at 1 AU calculated with the new model are about twice those expected on the basis of models now in use. In contrast to earlier models, results do not depend critically on the fluence from any one event.

  2. Transverse Beam Emittance Measurements of a 16 MeV Linac at the Idaho Accelerator Center

    SciTech Connect

    S. Setiniyaz, T.A. Forest, K. Chouffani, Y. Kim, A. Freyberger

    2012-07-01

    A beam emittance measurement of the 16 MeV S-band High Repetition Rate Linac (HRRL) was performed at Idaho State University's Idaho Accelerator Center (IAC). The HRRL linac structure was upgraded beyond the capabilities of a typical medical linac so it can achieve a repetition rate of 1 kHz. Measurements of the HRRL transverse beam emittance are underway that will be used to optimize the production of positrons using HRRL's intense electron beam on a tungsten converter. In this paper, we describe a beam imaging system using on an OTR screen and a digital CCD camera, a MATLAB tool to extract beamsize and emittance, detailed measurement procedures, and the measured transverse emittances for an arbitrary beam energy of 15 MeV.

  3. Modification & alignment of beam line of 10 MeV RF electron beam accelerator

    NASA Astrophysics Data System (ADS)

    Barnwal, R.; Ghodke, S. R.; Bhattacharjee, D.; Kumar, M.; Jayaprakash, D.; Chindarkar, A. R.; Mishra, R. L.; Dolas, S.; Kulkarni, S. Y.; Kumar, M.; P, Dixit K.; S, Acharya; Barje, S. R.; Lawangare, N. K.; C, Saroj P.; Nimje, V. T.; Chandan, S.; Tillu, A. R.; V, Sharma; Chavan, R. B.; V, Yadav; P, Roychowdhury; Mittal, K. C.; Chakravarthy, D. P.; Ray, A. K.

    2008-05-01

    A 10 MeV, 10 kW RF industrial Electron linac designed and developed at BARC is installed at the Electron Beam Center Kharghar, Navi Mumbai. The entire RF accelerator assembly consists of Electron gun, RF source, RF linac structure, Beam diagnostic chamber, Drift tube, Scanning magnet, Beam sensing aperture, Scan horn, and is spread over two floors at EBC. The paper discusses in detail about the alignment procedure adopted for the equipments of 10 MeV RF beamline. The complete electron beamline will be maintained under ultra high vacuum of the order of 10-7 torr. The paper discusses about the present problem of alignment, measurement technique of alignment, reason for misalignment, possible ways to solve the problem, equipment used for alignment, supports & arrestors, verification of alignment under vacuum

  4. Analysis of the pp analyzing-power data at 50.04 Mev

    NASA Astrophysics Data System (ADS)

    Stoks, V. G. J.; de Swart, J. J.

    1990-07-01

    The recent, very accurate proton-proton analyzing-power measurements by the Zürich group at tlab = 50.04 MeV are analyzed. We show that in order to arrive at a proper description of these data, the magnetic-moment interaction has to be included in all partial waves. It is also shown that some of the approximations made in the literature, when trying to incorporate this magnetic-moment interaction, are inadequate. From these beautiful data one can now determine quite accurately the phase shifts at 50 MeV. We compare our results with the phase shifts found in other phase-shift analyses. Some of our phase shifts differ by 6-9 standard deviations from these analyses. Finally, we compare the predictions of some well-known nucleon-nucleon potential models with these high-precision data.

  5. A three-dimensional study of 30- to 300-MeV atmospheric gamma rays

    NASA Technical Reports Server (NTRS)

    Thompson, D. J.

    1974-01-01

    A three-dimensional study of atmospheric gamma rays with energy greater than 30 MeV has been carried out. A knowledge of these atmospheric secondaries has significant applications to the study of cosmic gamma rays. For detectors carried on balloons, atmospherically produced gamma rays are the major source of background. For satellite detectors, atmospheric secondaries provide a calibration source. Experimental results were obtained from four balloon flights from Palestine, Texas, with a 15 cm by 15 cm digitized wire grid spark chamber. The energy spectrum for downward-moving gamma rays steepens with increasing atmospheric depth. Near the top of the atmosphere, the spectrum steepens with increasing zenith angle. A new model of atmospheric secondary production has calculated the depth, the energy, and the zenith angle dependence of gamma rays above 30 MeV, using a comprehensive three-dimensional Monte Carlo model of the nucleon-meson-electromagnetic cascade.

  6. The New Sorgentina Fusion Source-NSFS: 14 MeV neutrons for fusion and beyond

    NASA Astrophysics Data System (ADS)

    Pietropaolo, A.; Console Camprini, P.; Agostini, P.; Amendola, R.; Angelone, M.; Bernardi, D.; Bruni, F.; Capogni, M.; Colognesi, D.; Faccini, R.; Filabozzi, A.; Flammini, D.; Fiori, F.; Frisoni, M.; Grazzi, F.; Pillon, M.; Pizzuto, A.; Quintieri, L.; Sacchetti, F.; Valente, P.

    2016-09-01

    The importance of the design for the realization of an intense 14 MeV neutron facility devoted to test and validate materials suitable for harsh neutron environments, such as a fusion reactor, is well established. The “New Sorgentina” Fusion Source (NSFS) is a project that proposes an intense D-T 14 MeV neutron source achievable with T and D ion beams impinging on 2 m radius rotating targets. NSFS may produce about 1015 n/s at the target and has to be intended as an European facility that maybe realized in a few years, once provided a preliminary technological program devoted to the operation of the ion source in continuous mode, target heat loading/removal, target and tritium handling, inventor as well as site licensing. In this contribution, the main characteristics of NSFS project will be presented and its possible use as a multipurpose facility outlined.

  7. Modification of ROSPEC to cover neutrons from thermal to 18 MeV.

    PubMed

    Ing, H; Djeffal, S; Clifford, T; Li, L; Noulty, R; Machrafi, R

    2007-01-01

    Rotating Spectrometer (ROSPEC) is a neutron spectrometer designed to measure neutron energy distributions, and provide accurate neutron dosimetry. It is a completely self-contained unit and measures neutron energy via recoiling protons in gas proportional counters. Each of the four original gas counters is dedicated to a particular neutron energy range dictated by sensitivity to gamma rays at the low energy end of the spectrum and by proton collisions with the counter walls at the high energy end. Introduced originally in 1992, ROSPEC has a proven operational record with a program of continued upgrades. The operating range of the original ROSPEC spans 50 keV-4.5 MeV. The range of the ROSPEC has now been extended down to include epithermal and thermal neutrons by adding two 2 in. (3)He counters. Also, an optional simple scintillation spectrometer was designed to extend the upper limit of ROSPEC up to 18 MeV.

  8. The response of CR-39 nuclear track detector to 1-9 MeV protons

    DOE PAGESBeta

    Sinenian, N.; Rosenberg, M. J.; Manuel, M.; McDuffee, S. C.; Casey, D. T.; Zylstra, A. B.; Rinderknecht, H. G.; Johnson, M. Gatu; Seguin, F. H.; Frenje, J. A.; et al

    2011-10-28

    The response of CR-39 nuclear track detector (TasTrak®) to protons in the energy range of 0.92-9.28 MeV has been studied. Previous studies of the CR-39 response to protons have been extended by examining the piece-to-piece variability in addition to the effects of etch time and etchant temperature; it is shown that the shape of the CR-39 response curve to protons can vary from piece-to-piece. The effects due to the age of CR-39 have also been studied using 5.5 MeV alpha particles over a 5-year period. Track diameters were found to degrade with the age of the CR-39 itself rather thanmore » the age of the tracks, consistent with previous studies utilizing different CR-39 over shorter time periods.« less

  9. STATUS OF NEW 2.5 MEV TEST FACILITY AT SNS

    SciTech Connect

    Aleksandrov, Alexander V; Champion, Mark; Crofford, Mark T; Kang, Yoon W; Menshov, Alexander A; Roseberry, Jr., R Tom; Stockli, Martin P; Webster, Anthony W; Welton, Robert F; Zhukov, Alexander P

    2014-01-01

    A new 2.5MeV beam test facility is being built at SNS. It consists of a 65 keV H- ion source, a 2.5MeV RFQ, a beam line with various beam diagnostics and a 6 kW beam dump. The facility is capable of producing one-ms-long pulses at 60Hz repetition rate with up to 50mA peak current. The commissioning with reduced average beam power is planned for fall 2014 to verify operation of all systems. The full power operation is scheduled to begin in 2015. The status of the facility will be presented as well as a discussion of the future R&D program.

  10. rvec p + sup 13 rvec C elastic scattering at 500 MeV

    SciTech Connect

    Tanaka, N.

    1990-01-01

    For the first time, an elastic scattering experiment was performed at LAMPF using polarized protons and a polarized target nucleus ({rvec p} + {sup 13}{rvec C}). The analyzing powers (A{sub ooon}({Theta})) and (A{sub oonn}({Theta})) were measured using an incident beam energy of 500 MeV over the laboratory angular range of 10{degree}--30{degree}. Motivation for the experiment and some preliminary results and conclusions are presented. 12 refs., 7 figs.

  11. The Origin of the Cosmic Gamma-ray Background in the MeV Range

    NASA Astrophysics Data System (ADS)

    Ruiz-Lapuente, Pilar; The, Lih-Sin; Hartmann, Dieter H.; Ajello, Marco; Canal, Ramon; Röpke, Friedrich K.; Ohlmann, Sebastian T.; Hillebrandt, Wolfgang

    2016-04-01

    There has been much debate about the origin of the diffuse γ-ray background in the MeV range. At lower energies, AGNs and Seyfert galaxies can explain the background, but not above ≃0.3 MeV. Beyond ˜10 MeV blazars appear to account for the flux observed. That leaves an unexplained gap for which different candidates have been proposed, including annihilations of WIMPS. One candidate is Type Ia supernovae (SNe Ia). Early studies concluded that they were able to account for the γ-ray background in the gap, while later work attributed a significantly lower contribution to them. All those estimates were based on SN Ia explosion models that did not reflect the full 3D hydrodynamics of SN Ia explosions. In addition, new measurements obtained since 2010 have provided new, direct estimates of high-z SN Ia rates beyond z ˜ 2. We take into account these new advances to see the predicted contribution to the gamma-ray background. We use here a wide variety of explosion models and a plethora of new measurements of SN Ia rates. SNe Ia still fall short of the observed background. Only for a fit, which would imply ˜150% systematic error in detecting SN Ia events, do the theoretical predictions approach the observed fluxes. This fit is, however, at odds at the highest redshifts with recent SN Ia rate estimates. Other astrophysical sources such as flat-spectrum radio quasars do match the observed flux levels in the MeV regime, while SNe Ia make up to 30%-50% of the observed flux.

  12. Scattering of {sup 8}He on {sup 208}Pb at 22 MeV

    SciTech Connect

    Marquinez-Duran, G.; Sanchez-Benitez, A. M.; Martel, I.; Berjillos, R.; Duenas, J. A.; Parkar, V. V.; Acosta, L.; Rusek, K.; Alvarez, M. A. G.; Gomez-Camacho, J.; Borge, M. J. G.; Cruz, C.; Cubero, M.; Pesudo, V.; Tengblad, O.; Chbihi, A.; Fernandez-Garcia, J. P.; Moro, A. M.; Fernandez-Martinez, B.; Labrador, J. A.; and others

    2013-06-10

    The skin nucleus {sup 8}He is investigated by measuring the angular distribution of the elasticly scattered {sup 8}He and the {sup 6,4}He fragments produced in the collision with a {sup 208}Pb target at 22 MeV, just above the Coulomb barrier. The experiment was carried out at SPIRAL/GANIL in 2010. Here we present preliminary results for the elastic scattering.

  13. Comments on (n, charged particle) reactions at E/sub n/ = 14 MeV

    SciTech Connect

    Haight, R.C.

    1984-01-01

    The study of charged particles produced by bombarding materials with 14 MeV neutrons is important for the development of fusion reactors and for biomedical applications as well as for the basic understanding of nuclear reactions. Several experimental techniques for investigating these reactions are discussed here. The interpretation of the data requires the consideration of several possible reaction mechanisms including equilibrium and preequilibrium particle emission and, for light nuclei, sequential particle emission, final state interactions, and the effect of resonances. 17 references.

  14. Voltage holding study of 1 MeV accelerator for ITER neutral beam injector

    SciTech Connect

    Taniguchi, M.; Kashiwagi, M.; Umeda, N.; Dairaku, M.; Takemoto, J.; Tobari, H.; Tsuchida, K.; Yamanaka, H.; Watanabe, K.; Kojima, A.; Hanada, M.; Sakamoto, K.; Inoue, T.

    2012-02-15

    Voltage holding test on MeV accelerator indicated that sustainable voltage was a half of that of ideal quasi-Rogowski electrode. It was suggested that the emission of the clumps is enhanced by a local electric field concentration, which leads to discharge initiation at lower voltage. To reduce the electric field concentration in the MeV accelerator, gaps between the grid supports were expanded and curvature radii at the support corners were increased. After the modifications, the accelerator succeeded in sustaining -1 MV in vacuum without beam acceleration. However, the beam energy was still limited at a level of 900 keV with a beam current density of 150 A/m{sup 2} (346 mA) where the 3 x 5 apertures were used. Measurement of the beam profile revealed that deflection of the H{sup -} ions was large and a part of the H{sup -} ions was intercepted at the acceleration grid. This causes high heat load on the grids and the breakdowns during beam acceleration. To suppress the direct interception, new grid system was designed with proper aperture displacement based on a 3D beam trajectory analysis. As the result, the beam deflection was compensated and the voltage holding during the beam acceleration was improved. Beam parameter of the MeV accelerator was increased to 980 keV, 185 A/m{sup 2} (427 mA), which is close to the requirement of ITER accelerator (1 MeV, 200 A/m{sup 2}).

  15. Isotopic production cross sections in proton-nucleus collisions at 200 MeV

    SciTech Connect

    Machner, H.; Aschman, D.G.; Steyn, D.; Baruth-Ram, K.; Carter, J.; Sideras-Haddad, E.; Sellschop, J.P.F.; Cowley, A.A.; Goldenbaum, F.; Nangu, B.M.; Spoelstra, B.; Pilcher, J.V.; Smit, F.D.

    2006-04-15

    Intermediate-mass fragments from the interaction of {sup 27}Al, {sup 59}Co, and {sup 197}Au with 200-MeV protons were measured in an angular range from 20 deg. to 120 deg. in the laboratory system. The fragments, ranging from isotopes of helium up to isotopes of carbon, were isotopically resolved. Double-differential cross sections, energy-differential cross sections, and total cross sections were extracted.

  16. Nuclear multifragmentation by 700–1500 MeV photons: New data of GRAAL experiment

    SciTech Connect

    Nedorezov, V. G. Lapik, A. M.; Collaboration: GRAAL Collaboration

    2015-12-15

    The cross sections of carbon nucleus photodisintegration into protons and neutrons with high multiplicity for photon energies from 700 to 1500 MeV were measured. The experiment was performed at the tagged photon beam of the GRAAL setup using the wide-aperture detector LAGRANγE. It was shown that multifragmentation up to complete disintegration into separate nucleons is initiated by elementary reactions of meson photoproduction with a subsequent intranuclear cascade.

  17. Accelerator driven system based on plutonium subcritical reactor and 660 MeV phasotron

    NASA Astrophysics Data System (ADS)

    Arkhipov, V. A.; Barashenkov, V. S.; Buttsev, V. S.; Chultem, D.; Dudarev, S. Yu.; Furman, V. I.; Gudowski, W.; Janczyszyn, J.; Maltsev, A. A.; Onischenko, L. M.; Pogodajev, G. N.; Polanski, A.; Popov, Yu. P.; Puzynin, I. V.; Sissakian, A. N.; Taczanowski, S.

    1999-11-01

    The proposal presents a PLUTONIUM BASED ENERGY AMPLIFIER TESTING CONCEPT which employs a plutonium subcritical assembly and a 660 MeV proton accelerator, operating in the the JINR (Dubna, Russia). To make the present conceptual design of the Plutonium Energy Amplifier we have chosen a nominal unit capacity of 20 kW (thermal). This corresponds to the multiplication coefficient keff between 0.94 and 0.95 and the energetic gain about 20.

  18. Biomedical user facility at the 400-MeV Linac at Fermilab

    SciTech Connect

    Chu, W.T.

    1993-12-01

    In this paper, general requirements are discussed on a biomedical user facility at the Fermilab`s 400-MeV Linac, which meets the needs of biology and biophysics experiments, and a conceptual design and typical operations requirements of the facility is presented. It is assumed that no human patient treatment will take place in this facility. If human patients were treated, much greater attention would have to be paid to safeguarding the patients.

  19. Impurity/defect interactions during MeV Si{sup +} ion implantation annealing

    SciTech Connect

    Agarwal, A.; Koveshnikov, S.; Christensen, K.

    1995-08-01

    Ion implantation of dopant atoms at MeV energies is currently being explored in several integrated circuit device manufacturing processes. MeV implantation offers immediate advantages such as vertical well modulation, latch-up protection, device structure isolation, and reduced temperature processing. Simultaneously, it presents an opportunity to achieve {open_quotes}proximity{close_quotes} gettering of impurities from the active device region by placing high impurity solubility and/or secondary defect gettering sites within microns of the surface. If the MeV implanted species is a dopant ion, all three gettering mechanisms, i.e, segregation, relaxation and injection, can be involved in the gettering process, complicating the analysis and optimization of the process. However, investigation of gettering using non-dopant Si{sup +} ion damage allows the relaxation component of the gettering process to be isolated and examined separately. In general, gettering is verified by a reduction in impurity concentration in the region of interest, usually the device region, and/or a build-up of concentration/precipitation in a non-device sink region. An alternate and more meaningful approach is to use simple devices as materials characterization probes via changes in the electrical activity of the gettering sites. Device space charge probes also allow the evolution of the defect sites upon contamination to be tracked. We report here results of the electrical, structural, and chemical characterization of MeV implanted Si{sup +} damage using Deep Level Transient Spectroscopy (DLTS), Transmission Electron Microscopy (TEM), and Secondary Ion Mass Spectroscopy (SIMS). The damage has been characterized both as a function of annealing from 600 to 1100{degrees}C for 1 hr, and after contamination with Fe followed by low temperature gettering annealing.

  20. Irradiation Effects of 22 and 240 MeV Protons on Several Transistors and Solar Cells

    NASA Technical Reports Server (NTRS)

    Hulten, W. C.; Honaker, W. C.; Patterson, John L.

    1961-01-01

    The work covered in this report has been directed toward the investigation of the irradiation effects of 22 and 240 MeV protons on several transistors, solar cells, resistors, and condensers to be used in the space radiation environment. The experimental data indicated definite detrimental effects on transistors and solar cells but no apparent effects on the types of resistors and condensers tested. The detrimental effects are of two distinct types: transient and permanent.

  1. Gamma radiation from the Crab nebula above 35 MeV

    NASA Technical Reports Server (NTRS)

    Kniffen, D. A.; Hartman, R. C.; Thompson, D. J.; Bignami, G. F.; Fichtel, C. E.; Oegelman, H.; Tuemer, T.

    1974-01-01

    Electromagnetic radiation from the Crab nebula were observed, showing that the Crab is unique among strong X-ray sources in that major component in the low energy range (1 to 10 KeV) shows little or no temporal variation. Observations of the Crab above 35 MeV were made with the high energy gamma ray telescope flown on SAS-2. The detector and technique are described in detail.

  2. Direct experimental reconstruction of the pp elastic scattering matrix at 579 MeV

    SciTech Connect

    Aprile, E.; Eisenegger, C.; Hausammann, R.; Heer, E.; Hess, R.; Lechanoine-Leluc, C.; Leo, W.R.; Morenzoni, S.; Onel, Y.; Rapin, D.; Mango, S.

    1981-04-20

    We have made, for the first time, a direct reconstruction of the pp elastic scattering matrix at 579 MeV from a series of experiments performed with a polarized beam line. Fifteen observables consisting of the polarization, two-spin correlation and transfer parameters, and three-spin parameters were measured at seven angles between 66/sup 0/ and 90/sup 0/ center of mass. The experimental results and reconstructed amplitudes are presented and compared to a phase-shift analysis.

  3. Celestial diffuse gamma radiation above 30 MeV observed by SAS-2

    NASA Technical Reports Server (NTRS)

    Fichtel, C. E.; Kniffen, D. A.; Hartman, R. C.

    1973-01-01

    The Small Astronomy Satellite (SAS)-2, launched on November 15, 1972, carried into orbit a 32-deck magnetic-core digitized spark chamber gamma ray telescope to study celestial gamma radiation in the energy range above 30 MeV. In the study of several regions with b sub 2 15 deg, a finite, diffuse flux of gamma rays with a steep energy spectrum in the energy region from 35 to 200 MeV is observed. Representing the energy spectrum by a power law of the form dJ/dE = AE to - alpha power over this energy range, alpha is found along with the integral flux above 100 MeV. Combining this result with existing low energy gamma ray data yields an energy spectrum which is not a simple power law in energy, as in the X-ray region, but which demonstrates first an increase and then a decrease in slope, consistent within uncertainties with that predicted by cosmological theories, including the continuous production of high energy gamma rays primarily from neutral pi mesons throughout the history of the universe.

  4. Linac-beam characterizations at 600 MeV using optical transition radiation diagnostics

    NASA Astrophysics Data System (ADS)

    Lumpkin, A. H.; Berg, W. J.; Yang, B. X.; White, M.

    1998-12-01

    Selected optical diagnostics stations were upgraded in anticipation of low-emittance, bright electron beams from a thermionic rf gun or a photoelectric rf gun on the Advanced Photon Source (APS) injector linac. The upgrades include the installation of optical transition radiation (OTR) screens, transport lines, and cameras for use in transverse beam size measurements and longitudinal profile measurements. Using beam from the standard thermionic gun, tests were done at 50 MeV and 400 to 650 MeV. Data were obtained on the limiting spatial (σ˜200 μm) and temporal resolutions (300 ms) of the Chromox (Al2O3:Cr) screen (250 μm thick) in comparison to the OTR screens. Both charge-ecoupled device (CCD) and charge-injection device (CID) video cameras were used, as well as a Hamamatsu C5680 synchroscan streak camera operating at a vertical deflection rate of 119.0 MHz (the 24th subharmonic of the S-band 2856 MHz frequency). Beam transverse sizes as small as σx=60 μm for a 600 MeV beam and micropulse bunch lengths of στ<3 ps have been recorded for macropulse-averaged behavior with charges of about 2 to 3 nC per macropulse. These techniques are applicable to linac-driven, fourth-generation light source R&D experiments, including the APS's SASE FEL experiment.

  5. μCF based 14 MeV intense neutron source

    NASA Astrophysics Data System (ADS)

    Anisimov, V. V.; Cavalleri, E.; Karmanov, F. I.; Konobeyev, A. Yu.; Latysheva, L. N.; Ponomarev, L. I.; Pshenichnov, I. A.; Slobodtchouk, V. I.; Vecchi, M.

    1999-06-01

    Results of a design study for an advanced scheme of a μCF based 14 MeV intense neutron source for test material irradiation including the liquid lithium primary target and a low temperature liquid deuterium-tritium (D-T) mixture as a secondary target are presented. According to this scheme negative pions are produced inside a 150-cm-long 0.75-cm-radius lithium target. Pions and muons resulting from the pion decay in flight are collected in the backward direction and stopped in the D-T mixture. The fusion chamber has the shape of a 10-cm-radius sphere surrounded by two 0.03-cm-thickness titanium shells. Assuming 100 fusions per muon in this scheme one can produce 14-MeV neutrons with a source strength up to 1017 n/s. A neutron flux of up to 1014 n/cm2/s can be achieved in a test volume of about 2.5 l and on the surface of about 350 cm2. The results of the thermophysical and thermomechanical analysis show that the technological limits are not exceeded. This source has the advantage of producing the original 14 MeV fusion spectrum without tails, isotropically into a 4π solid angle, contrary to the d-Li stripping neutron source.

  6. Measurement of Ay for the pd Breakup Reaction at 250 MeV

    SciTech Connect

    Maeda, Y.; Uesaka, T.; Kawabata, T.; Suda, K.; Sasamoto, Y.; Sakaguchi, S.; Sakai, H.; Yako, K.; Sasano, M.; Noji, S.; Hatanaka, K.; Tamii, A.; Shimizu, Y.; Takechi, M.; Tameshige, Y.; Matsubara, H.; Sagara, K.; Wakasa, T.; Dozono, M.; Ihara, E.

    2007-06-13

    From the recent studies, it has been found that the differential cross sections of the elastic Nd scattering at the energy below 150 MeV can be well reproduced by incorporating the 3NF in the Faddeev calculation based on modern nucleon-nucleon (NN) interactions. On the other hand, the differential cross sections of nd and pd at 250 MeV show large discrepancies between the data and the Faddeev calculations with 3NF. It indicates the presence of the missing features of the three nucleon system at this energy region. For the next step of the 3NF study, we measured the vector analyzing power Ay and the differential cross sections for the 2H(p, pp)n breakup reaction at 250 MeV. The experiment was carried out by detecting two protons in the final state with using the double-armed spectrometer Grand Raiden (GR) and Large Acceptance Spectrometer (LAS) at Research Center for Nuclear Physics (RCNP). These data provide important information on the 3NF effects and make a discrimination between 3NF models.

  7. Design study of a 9 MeV compact cyclotron system for PET

    NASA Astrophysics Data System (ADS)

    Lee, Byeong-No; Shin, Seung-Wook; Song, Hoseung; Kim, Hyun-Wook; Chai, Jong-Seo

    2013-06-01

    A cyclotron is an accelerator which can be applied to both cancer diagnosis and treatment. Among commercially sold cyclotrons, the major energy is used for positron emission tomography (PET) ranges from 10 to 20 MeV. In this research, 9 MeV compact cyclotron for PET was designed. The research was conducted on the response cross section and the yield for the energy distribution to decide the design features. Also, it was determined the specifications on the basis of the fluoro-deoxy-glucose (FDG) maximum dose. The machine, which has a 20 uA beam current, is designed to be installed in small-to-medium-sized hospitals in local cities because of its relatively light weight (6 tons). This compact cyclotron, which provides 9-MeV proton beams, is composed of a azimuthally varying field (AVF) electromagnet, 83-MHz RF systems with a 20 kW amplifier, a panning ion gauge (PIG) type ion-source for negative hydrogen, and a double-stage high-vacuum system. The basic model design was done by using 3-D CAD program, CATIA and all the field calculations were performed using commercial electromagnetic field analysis code, OPERA-3D TOSCA. From this research, we expect a time reduction for FDG production, a decrease of radioactive exposure for workers, and an equipment cost reduction.

  8. 1 MeV, 10 kW DC electron accelerator for industrial applications

    NASA Astrophysics Data System (ADS)

    Nayak, B.; Acharya, S.; Bhattacharjee, D.; Bakhtsingh, R. I.; Rajan, R.; Sharma, D. K.; Dewangan, S.; Sharma, V.; Patel, R.; Tiwari, R.; Benarjee, S.; Srivastava, S. K.

    2016-03-01

    Several modern applications of radiation processing like medical sterilization, rubber vulcanization, polymerization, cross-linking and pollution control from thermal power stations etc. require D.C. electron accelerators of energy ranging from a few hundred keVs to few MeVs and power from a few kilowatts to hundreds of kilowatts. To match these requirements, a 3 MeV, 30 kW DC electron linac has been developed at BARC, Mumbai and current operational experience of 1 MeV, 10 kW beam power will be described in this paper. The LINAC composed mainly of Electron Gun, Accelerating Tubes, Magnets, High Voltage source and provides 10 kW beam power at the Ti beam window stably after the scanning section. The control of the LINAC is fully automated. Here Beam Optics study is carried out to reach the preferential parameters of Accelerating as well as optical elements. Beam trials have been conducted to find out the suitable operation parameters of the system.

  9. The 2-MEV model: Constancy of adolescent environmental values within an 8-year time frame

    NASA Astrophysics Data System (ADS)

    Bogner, F. X.; Johnson, B.; Buxner, S.; Felix, L.

    2015-08-01

    The 2-MEV model is a widely used tool to monitor children's environmental perception by scoring individual values. Although the scale's validity has been confirmed repeatedly and independently as well as the scale is in usage within more than two dozen language units all over the world, longitudinal properties still need clarification. The purpose of the present study therefore was to validate the 2-MEV scale based on a large data basis of 10,676 children collected over an eight-year period. Cohorts of three different US states contributed to the sample by responding to a paper-and-pencil questionnaire within their pre-test initiatives in the context of field center programs. Since we used only the pre-program 2-MEV scale results (which is before participation in education programs), the data were clearly unspoiled by any follow-up interventions. The purpose of analysis was fourfold: First, to test and confirm the hypothesized factorized structure for the large data set and for the subsample of each of the three states. Second, to analyze the scoring pattern across the eight years' time range for both preservation and utilitarian preferences. Third, to investigate any age effects in the extracted factors. Finally, to extract suitable recommendations for educational implementation efforts.

  10. New COMPTEL results on pulsar studies at MeV energies

    NASA Technical Reports Server (NTRS)

    Hermsen, W.; Kuiper, L.; Schoenfelder, V.; Strong, A. W.; Bennett, K.; Much, R.; McConnell, M.; Ryan, J.; Carraminana, A.

    1997-01-01

    The Compton telescope (COMPTEL) onboard the Compton Gamma Ray Observatory (CGRO) detected the pulsar PSR B1951-32 at MeV energies, and found indications of a signal from PSR B0656+14. In the combined spectra from COMPTEL and the energetic gamma ray experiment telescope (EGRET) onboard CGRO, it can be seen that the maximum luminosities of these objects are reached in the COMPTEL energy range. These spectra can be compared with those from four other pulsars observed in MeV energies with COMPTEL. The spectral properties of five of the six pulsars, Vela, PSR B1509-58, PSR B1951-32 and PSR B0656+14, require breaks and bends at MeV energies. The sixth pulsar, the Crab pulsar, approximately follows a power law flux relation from keV to GeV energies. It is concluded that this spectral behavior may play a role in the discrimination between current gamma ray emission models.

  11. Trends and applications for MeV electrostatic ion beam accelerators

    NASA Astrophysics Data System (ADS)

    Norton, G. A.; Stodola, S. E.

    2014-08-01

    The 1970s into the 1980s saw a major broadening of applications for electrostatic accelerators. Prior to this time, all accelerators were used primarily for nuclear structure research. In the 70s there was a significant move into production ion implantation with the necessary MeV ion beam analysis techniques such as RBS and ERD. Accelerators are still being built for these materials analysis techniques today. However, there is still a great ongoing expansion of applications for these machines. At the present time, the demand for electrostatic accelerators is near an all time high. The number of applications continues to grow. This paper will touch on some of the current applications which are as diverse as nuclear fission reactor developments and pharmacokinetics. In the field of nuclear engineering, MeV ion beams from electrostatic accelerators are being used in material damage studies and for iodine and actinide accelerator mass spectrometry (AMS). In the field of pharmacokinetics, electrostatic MeV accelerators are being used to detect extremely small amounts of above background 14C. This has significantly reduced the time required to reach first in human studies. These and other applications will be discussed.

  12. Ion desorption from frozen H 2O irradiated by MeV heavy ions

    NASA Astrophysics Data System (ADS)

    Collado, V. M.; Farenzena, L. S.; Ponciano, C. R.; Silveira, E. F. da; Wien, K.

    2004-10-01

    Nitrogen (0.13-0.85 MeV) and 252Cf fission fragments (˜65 MeV) beams are employed to sputter positive and negative secondary ions from frozen water. Desorption yields are measured for different ice temperatures and projectile energies. Target surface is continuously refreshed by condensed water while the target temperature varies and ice thickness changes. In both projectile energy ranges, the preferentially ejected ions are H +, H2+ and (H 2O) nH +-cluster ions. The yields of the corresponding negative ions H - and (H 2O) nO - or (H 2O) nOH - are 1-2 orders of magnitude lower. The (H 2O) nH + desorption yields decrease exponentially as the cluster size, n, increases. In the low energy range, the desorption of positive ion clusters may occur in a two-step process: first, desorption of preformed H 2O clusters and, then, ionization by H + or H 3O + capture. For 0.81 MeV N + projectile ions, the cluster ion emission contributes with 0.05% to the total H 2O desorbed yield. There are indications that emission of the (H 2O) nH + disappears for an electronic energy loss lower than 20 eV/Å. For the high energy range, desorption of small ion clusters is particularly enhanced, revealing that a fragmentation process also exists.

  13. ({ital p},{ital d}) reaction on {sup 62}Ni at 65 MeV

    SciTech Connect

    Matoba, M.; Kurohmaru, K.; Iwamoto, O.; Nohtomi, A.; Uozumi, Y.; Sakae, T.; Koori, N.; Ohgaki, H.; Ijiri, H.; Maki, T.; Nakano, M.; Sen Gupta, H.M.

    1996-04-01

    The {sup 62}Ni({ital p},{ital d}){sup 61}Ni reaction has been studied with 65 MeV polarized protons. Angular distributions of the differential cross section and analyzing power have been measured for neutron hole states in {sup 61}Ni up to an excitation energy of 7 MeV. The data analysis with a standard distorted-wave Born approximation theory provides transferred angular momenta {ital l} and {ital j} and spectroscopic factors for several strongly excited states. The 1{ital f}{sub 7/2} hole state spreads largely in the excitation energy region of 2{endash}6 MeV, while the 1{ital f}{sub 5/2}, 2{ital p}{sub 3/2}, and 2{ital p}{sub 1/2} hole states into only 2{endash}4 levels. The strength function of the 1{ital f}{sub 7/2} hole state is analyzed with an asymmetrical Lorentzian function. The damping mechanism of the single hole states is discussed. {copyright} {ital 1996 The American Physical Society.}

  14. A 0. 5 to 3. 0 MeV monoenergetic positron beam

    SciTech Connect

    Huomo, H.; AsokaKumar, P.; Henderson, S.D.; Phlips, B.F.; Mayer, R.; McDonough, J.; Hacker, H.; McCorkle, S.; Schnitzenbaumer, P.; Greenberg, J.S.

    1988-01-01

    An adjustable, 0.5--3 MeV monoenergetic positron beam has been constructed at Brookhaven. Currently a /sup 22/Na source with a W(100) foil transmission moderator produces a 1.1 mm FWHN beam with an intensity of 3/times/10/sup 5/ e/sup +//sec at a target located downstream from the accelerator. The divergence of the beam is less than 0.1/degree/ at 2.2 MeV energy. A SOA gun with 2 lens transport system brings the beam to a focus at the entrance of an electrostatic 3 MeV Dynamitron accelerator. The post acceleration beam transport system comprises 3 focusing solenolds, 4 sets of steering magnets and a 90/degree/ double focusing bending magnet. The beam energy spread at the target is <1 keV FWHN deduced from the beam size. Below we describe the positron extraction optics and acceleration, the construction of the beamline and the beam diagnostic devices. The salient beam parameters are listed at the end of this paper. 2 refs., 3 figs., 1 tab.

  15. Two nucleon systems at mπ~450MeV from lattice QCD

    DOE PAGESBeta

    Orginos, Kostas; Parreño, Assumpta; Savage, Martin J.; Beane, Silas R.; Chang, Emmanuel; Detmold, William

    2015-12-23

    Nucleon-nucleon systems are studied with lattice quantum chromodynamics at a pion mass ofmore » $$m_\\pi\\sim 450~{\\rm MeV}$$ in three spatial volumes using $n_f=2+1$ flavors of light quarks. At the quark masses employed in this work, the deuteron binding energy is calculated to be $$B_d = 14.4^{+3.2}_{-2.6} ~{\\rm MeV}$$, while the dineutron is bound by $$B_{nn} = 12.5^{+3.0}_{-5.0}~{\\rm MeV}$$. Over the range of energies that are studied, the S-wave scattering phase shifts calculated in the 1S0 and 3S1-3D1 channels are found to be similar to those in nature, and indicate repulsive short-range components of the interactions, consistent with phenomenological nucleon-nucleon interactions. In both channels, the phase shifts are determined at three energies that lie within the radius of convergence of the effective range expansion, allowing for constraints to be placed on the inverse scattering lengths and effective ranges. Thus, the extracted phase shifts allow for matching to nuclear effective field theories, from which low energy counterterms are extracted and issues of convergence are investigated. As part of the analysis, a detailed investigation of the single hadron sector is performed, enabling a precise determination of the violation of the Gell-Mann–Okubo mass relation.« less

  16. Simulation of electron behavior in PIG ion source for 9 MeV cyclotron

    NASA Astrophysics Data System (ADS)

    J. Mu, X.; Ghergherehchi, M.; H. Yeon, Y.; W. Kim, J.; S. Chai, J.

    2014-12-01

    In this paper, we focus on a PIG source for producing intense H-ions inside a 9 MeV cyclotron. The properties of the PIG ion source were simulated for a variety of electric field distributions and magnetic field strengths using a CST particle studio. After analyzing the secondary electron emission (SEE) as a function of both magnetic and electric field strengths, we found that for the modeled PIG geometry, a magnetic field strength of 0.2 T provided the best results in terms of the number of secondary electrons. Furthermore, at 0.2 T, the number of secondary electrons proved to be greatest regardless of the cathode potential. Also, the modified PIG ion source with quartz insulation tubes was tested in a KIRAMS-13 cyclotron by varying the gas flow rate and arc current, respectively. The capacity of the designed ion source was also demonstrated by producing plasma inside the constructed 9 MeV cyclotron. As a result, the ion source is verified as being capable of producing an intense H- beam and high ion beam current for the desired 9 MeV cyclotron. The simulation results provide experimental constraints for optimizing the strength of the plasma and final ion beam current at a target inside a cyclotron.

  17. Study of {sup 27}Al(n,x{gamma}) reactions up to a neutron energy of 400 MeV

    SciTech Connect

    Hitzenberger, H.; Pavlik, A.; Vonach, H.; Chadwick, M.B.; Haight, R.C.; Nelson, R.O.; Young, P.G.

    1994-06-01

    The prompt {gamma}-radiation from the interaction of fast neutrons with Al was measured using the white neutron beam of the WNR facility at the Los Alamos National Laboratory. Partial production cross sections for residual nuclei in the range from F to Al were measured from threshold up to 400 MeV by observing the most intense {gamma}-transitions between low lying levels of these nuclei. Two-dimensional neutron time-of-flight versus gamma pulse height spectra from the interaction of the neutrons with Al were observed after flight-paths of about 20 and 40 m with a high-purity Ge-detector. The neutron cross sections for prominent {gamma}-transitions in a large number of residual nuclei could be derived with typical uncertainties of 10--20% up to a neutron energy of 400 MeV. The energy resolution varies from {approx}0.2 MeV at 10 MeV to {approx}50 MeV at 400 MeV. In the low energy range (up to 60 MeV) the results are compared with nuclear model calculations using the code GNASH. A very good overall agreement is obtained without special adjustment of parameters.

  18. FTIR analysis of polyethylene terephthalate irradiated by MeV He+

    NASA Astrophysics Data System (ADS)

    Djebara, M.; Stoquert, J. P.; Abdesselam, M.; Muller, D.; Chami, A. C.

    2012-03-01

    The degradation induced by MeV He+ ions onto polyethylene terephthalate (PET) is investigated as a function of fluence and electronic stopping power (dE/dx)e. Stack samples of four 3.6 μm PET films are irradiated by 3.5 MeV He+ under vacuum and room temperature at fluence ranging from 1013 to 1.5 × 1015 He+ cm-2. The entrance energies range from 3.5 MeV for the front film to 0.573 MeV for the rear one at the beginning of the irradiation and the corresponding mean (dE/dx)e lie for pristine PET between 158 and 264 keV/μm. A Fourier transform infrared spectroscopy (FTIR) analysis is undertaken. The different stack films present similar damages with magnitude increase as the fluence goes up. Moreover, higher is the electronic stopping power (dE/dx)e more important is the damage. The evolution of the normalized integrated absorbance A(ϕ)/A0 of the internal reference 1410 cm-1 band as a function of the fluence ϕ presents a complex behavior characterized by a two-exponential decay associated to low and high fluence range. The analysis reveals clearly that the A(ϕ)/A0 of the characteristic benzene ring 1577 cm-1 band remains steady till fluence around 3 × 1014 He+ cm-2 and then decreases smoothly as fluence increases. The band appearing at 1610 cm-1, assigned to mono substituted benzene, presents an integrated absorbance A(ϕ) which rises progressively and levels off beyond a critical fluence around 4 × 1014 He+ cm-2. The cross section of the creation of the monosubstituted benzene lies between 3 × 10-15 and 6 × 10-15 cm2 for (dE/dx)e = 158 and 264 keV/μm, respectively. Drastic loss of crystallinity is induced by the MeV He+ ion irradiation in the polymer. The amorphization is monitored by the evolution of the specific bands of the trans and gauche ethylene glycol residue conformations. A sudden drop in the integrated absorbance of the 1340 cm-1 band which characterizes the trans conformation is observed at fluence around 2 × 1014 He+ cm-2. On the other hand, a

  19. Measurement of excitation function for 63Cu(n, p) 63Ni reaction up to En=15 MeV

    NASA Astrophysics Data System (ADS)

    Shibata, S.; Shibata, T.; Imamura, M.; Ohkubo, T.; Satoh, S.; Uwamino, Y.; Nogawa, N.; Baba, M.; Matsuyama, S.; Iwasaki, S.

    1999-01-01

    The excitation function for the 63Cu(n, p) 63Ni reaction were measured using neutrons produced by the T(p, n) reaction at En=˜1.5 MeV, D(d, n) at En=˜6.5 MeV and T(d, n) at En=˜14 MeV, respectively. Irradiations were performed using the dynamitron accelerator at the Fast Neutron Laboratory of Tohoku University. After irradiation, the nickel was separated by anion-exchange and solvent extraction. The 63Ni was measured by liquid scintillation method. The cross sections obtained were compared with the calculated values of JENDL-3.

  20. Search for narrow structures in the anti pp annihilation cross section from 1925 to 1955 MeV

    SciTech Connect

    Lowenstein, D I; Peaslee, D C; Bromberg, C

    1980-01-01

    The anti pp annihilation cross section has been measured over the CM energy range 1925 to 1955 MeV with an RMS resolution of +-2.5 MeV on the average. This search yields no evidence for narrow enhancements in the S(1936) region. Using an A + B/p dependent background, a two standard deviation upper limit of 9 mb-MeV is set for the integrated area of any resonance with mass between 1936 and 1942 and with width less than or equal to 4 MeV.

  1. Measurements of 15.11-MeV gamma-ray flux produced in the reactions C-12(p, p')-C-12*(15.11 MeV) and O-16(p, p' alpha)-C-12*(15.11 MeV)

    NASA Technical Reports Server (NTRS)

    Lapides, J. R.; Crannell, C. J.; Crannell, H.; Hornyak, W. F.; Seltzer, S. M.; Trombka, J. I.; Wall, N. S.

    1978-01-01

    The flux of 15.11 MeV gamma rays relative to the flux of 4.44 MeV gamma rays which are emitted from the corresponding states of C-12 are a sensitive measure of the spectrum of exciting particles in solar flares and other cosmic sources. Emission of 15.11 MeV gamma rays may result not only from the direct excitation of C-12 but also from the interaction O-16 (p,p' alpha) C-12* sup 15.11 MeV. Although the cross sections for the direct reaction was studied extensively, the cross section for the spallation interaction with O-16 is not reported in the literature. Preliminary measurements demonstrated the feasibility of measuring the production of 15.11 MeV gamma rays by proton interactions with O-16 using the University of Maryland cyclotron facility. For both carbon and oxygen targets the flux of 15.11 MeV gamma rays is being measured relative to the flux of 4.44 MeV gamma rays. The gamma ray emission from de-excitation of the giant dipole resonances is being measured.

  2. Post-Newtonian gravitational bremsstrahlung

    NASA Technical Reports Server (NTRS)

    Turner, M.; Will, C. M.

    1977-01-01

    Formulae and numerical results are presented for the gravitational radiation emitted during a low-deflection encounter between two massive bodies. Results are valid through post-Newtonian order within general relativity. The gravitational waveform, the total luminosity and total emitted energy, the angular distribution of emitted energy, and the frequency spectrum are discussed in detail. A method boosting the accuracy of these quantities to post Newtonian order is also presented. A numerical comparison of results with those of Peters, and of Kovacs and Thorne shows that the post Newtonian method is reliable to better than 0.1 percent at v = 0.1 c, to a few percent at v = 0.35 c, and to 10 to 20 percent at v = 0.5 c.

  3. Status of advanced bremsstrahlung converters

    SciTech Connect

    Halbleib, J.A.

    1980-01-01

    This paper is an attempt to review the somewhat ill-defined area of advanced converter research in a more or less chronological fashion. Section 2 reviews the early B/sub z/ work that was motivated by the CASINO project. More recent work makes liberal use of technology from ICF research using REBs is discussed in Sec. 3. Section 4 discusses possible directions for future research, some of which are being actively pursued at Sandia National Laboratories (SNL) and elsewhere.

  4. Single event upsets calculated from new ENDF/B-VI proton and neutron data up to 150 MeV

    SciTech Connect

    Chadwick, M.B.; Normand, E.

    1999-06-01

    Single-event upsets (SEU) in microelectronics are calculated from newly-developed silicon nuclear reaction recoil data that extend up to 150 MeV, for incident protons and neutrons. Calculated SEU cross sections are compared with measured data.

  5. Gamma rays of 1-30 MeV from the Vela Pulsar PSR 0833-45

    NASA Technical Reports Server (NTRS)

    Tumer, T.; Long, J.; Oneill, T.; Zych, A.; White, R. S.; Dayton, B.

    1983-01-01

    Results are reported for observations of gamma rays of 1-30 MeV from the Vela Pulsar PSR 0833 - 45 carried out with the UCR double scatter gamma ray telescope on a balloon launched from Alice Springs, Australia on November 10, 1981. An integrated flux of (5.3 + or - 1.3) x 10 to the -4th photons/sq cm/s is found for the Vela region above 2 MeV. This value, together with those for the energy intervals of 2-4, 4-7, and 7-15 MeV are in reasonable agreement with the power law found by COS-B at energies above 50 MeV. A sky contour map of the fluxes is shown.

  6. Neutron production in neutron-induced reactions at 96 MeV on 56Fe and 208Pb

    NASA Astrophysics Data System (ADS)

    Sagrado García, I. C.; Lecolley, J. F.; Lecolley, F. R.; Blideanu, V.; Ban, G.; Fontbonne, J. M.; Itis, G.; Lecouey, J. L.; Lefort, T.; Marie, N.; Steckmeyer, J. C.; Le Brun, C.; Blomgren, J.; Johansson, C.; Klug, J.; Orhn, A.; Mermod, P.; Olsson, N.; Pomp, S.; Osterlund, M.; Tippawan, U.; Prokofiev, A. V.; Nadel-Turonski, P.; Fallot, M.; Foucher, Y.; Guertin, A.; Haddad, F.; Vatre, M.

    2011-10-01

    Double-differential cross sections for neutron production were measured in 96-MeV neutron-induced reactions at The Svedberg Laboratory in Uppsala, Sweden. Measurements for Fe and Pb targets were performed using two independent setups: DECOI-DEMON, time-of-flight telescope dedicated to the detection of emitted neutrons with energies between a few and 50MeV and CLODIA-SCANDAL device devoted to measuring emitted neutrons with energies above 40MeV. Double-differential cross sections were measured for an angular range between 15 and 98 deg and with low-energy thresholds (≈2 MeV). Angular and energy distributions and total neutron emission cross sections have been obtained from those measurements. Results have been compared with predictions given by different models included in several transport codes (MCNPX, GEANT, TALYS, PHITS, and DYWAN) and with other experimental data (the EXFOR database).

  7. Elastic and inelastic neutron scattering from /sup 27/Al at 11, 14, and 17 MeV

    SciTech Connect

    Whisnant, C.S.; Dave, J.H.; Gould, C.R.

    1984-11-01

    Fast neutron scattering cross sections have been measured for /sup 27/Al using a neutron time-of-flight facility. Angular distributions were measured at angles from 20/sup 0/ to 160/sup 0/ in 5/sup 0/ increments, at incident neutron energies of 11, 14, and 17 MeV. Data are presented for elastic scattering and for inelastic scattering to the sum of the 0.84 and 1.01 MeV states, the 2.21 MeV state, and the sum of the 2.73, 2.98, and 3.00 MeV states. After correcting for compound nucleus effects, the elastic scattering cross sections are well reproduced by the spherical optical model using a linear energy dependence in the real well depth. The inelastic data are interpreted with a coupled channels calculation and the excited core model.

  8. Neutron total and scattering cross sections of /sup 6/Li in the few MeV region

    SciTech Connect

    Smith, A.; Guenther, P.; Whalen, J.

    1980-02-01

    Neutron total cross sections of /sup 6/Li are measured from approx. 0.5 to approx. 4.8 MeV at intervals of approx.< 10 keV. Neutron differential elastic-scattering cross sections are measured from 1.5 to 4.0 MeV at approx.> 10 scattering angles and at incident-neutron intervals of approx.< 100 keV. Neutron differential inelastic-scattering cross sections are measured in the incident-energy range 3.5 to 4.0 MeV. The experimental results are extended to lower energies using measured neutron total cross sections recently reported elsewhere by the authors. The composite experimental data (total cross sections from 0.1 to 4.8 MeV and scattering cross sections from 0.22 to 4.0 MeV) are interpreted in terms of a simple two-level R-matrix model which describes the observed cross sections and implies the reaction cross section in unobserved channels; notably the (n;..cap alpha..)t reaction (Q = 4.783 MeV). The experimental and calculational results are compared with previously reported results as summarized in the ENDF/B-V evaluated nuclear data file.

  9. Personal dose equivalent conversion coefficients for neutron fluence over the energy range of 20 to 250 MeV

    SciTech Connect

    Mclean, Thomas D; Justus, Alan L; Gadd, S Milan; Olsher, Richard H; Devine, Robert T

    2009-01-01

    Monte Carlo simulations were performed to extend existing neutron personal dose equivalent fluence-to-dose conversion coefficients to an energy of 250 MeV. Presently, conversion coefficients, H(p,slab)(10,alpha)/Phi, are given by ICRP-74 and ICRU-57 for a range of angles of radiation incidence (alpha = 0, 15, 30, 45, 60 and 75 degrees ) in the energy range from thermal to 20 MeV. Standard practice has been to base operational dose quantity calculations <20 MeV on the kerma approximation, which assumes that charged particle secondaries are locally deposited, or at least that charged particle equilibrium exists within the tally cell volume. However, with increasing neutron energy the kerma approximation may no longer be valid for some energetic secondaries such as protons. The Los Alamos Monte Carlo radiation transport code MCNPX was used for all absorbed dose calculations. Transport models and collision-based energy deposition tallies were used for neutron energies >20 MeV. Both light and heavy ions (HIs) (carbon, nitrogen and oxygen recoil nuclei) were transported down to a lower energy limit (1 keV for light ions and 5 MeV for HIs). Track energy below the limit was assumed to be locally deposited. For neutron tracks <20 MeV, kerma factors were used to obtain absorbed dose. Results are presented for a discrete set of angles of incidence on an ICRU tissue slab phantom.

  10. Measurements of galactic plane gamma ray emission in the energy range from 10 - 80 MeV

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Kniffen, D. A.

    1982-01-01

    A spark chamber gamma ray telescope was developed and flown to observe diffuse gamma ray emission from the central region of the galaxy. The extension of observations down to 10 MeV provides important new data indicating that the galactic diffuse gamma ray spectrum continues as a power law down to about 10 MeV, an observation in good agreement with recent theoretical predictions. Data from other experiments in the range from 100 keV to 10 MeV show a significant departure from the extension of the power-law fit to the medium energy observations reported here, possibly indicating that a different mechanism may be responsible for the emissions below and above a few MeV. The intensity of the spectrum above 10 MeV implies a galactic electron spectrum which is also very intense down to about 10 MeV. Electrons in this energy range cannot be observed in the solar cavity because of solar modulation effects. The galactic gamma ray data are compared with recent theoretical predictions.

  11. Measurements of galactic plane gamma-ray emission in the energy range 10-80 MeV

    NASA Technical Reports Server (NTRS)

    Bertsch, D. L.; Kniffen, D. A.

    1983-01-01

    A spark chamber gamma ray telescope was developed and flown to observe diffuse gamma ray emission from the central region of the galaxy. The extension of observations down to 10 MeV provides important new data indicating that the galactic diffuse gamma ray spectrum continues as a power law down to about 10 MeV, an observation in good agreement with recent theoretical predictions. Data from other experiments in the range from 100 keV to 10 MeV show a significant departure from the extension of the power-law fit to the medium energy observations reported here, possibly indicating that a different mechanism may be responsible for the emissions below and above a few MeV. The intensity of the spectrum above 10 MeV implies a galactic electron spectrum which is also very intense down to about 10 MeV. Electrons in this energy range cannot be observed in the solar cavity because of solar modulation effects. The galactic gamma ray data are compared with recent theoretical predictions. Previously announced in STAR as N83-17444

  12. Personal dose equivalent conversion coefficients for neutron fluence over the energy range of 20-250 MeV.

    PubMed

    Olsher, R H; McLean, T D; Justus, A L; Devine, R T; Gadd, M S

    2010-03-01

    Monte Carlo simulations were performed to extend existing neutron personal dose equivalent fluence-to-dose conversion coefficients to an energy of 250 MeV. Presently, conversion coefficients, H(p,slab)(10,alpha)/Phi, are given by ICRP-74 and ICRU-57 for a range of angles of radiation incidence (alpha = 0, 15, 30, 45, 60 and 75 degrees ) in the energy range from thermal to 20 MeV. Standard practice has been to base operational dose quantity calculations <20 MeV on the kerma approximation, which assumes that charged particle secondaries are locally deposited, or at least that charged particle equilibrium exists within the tally cell volume. However, with increasing neutron energy the kerma approximation may no longer be valid for some energetic secondaries such as protons. The Los Alamos Monte Carlo radiation transport code MCNPX was used for all absorbed dose calculations. Transport models and collision-based energy deposition tallies were used for neutron energies >20 MeV. Both light and heavy ions (HIs) (carbon, nitrogen and oxygen recoil nuclei) were transported down to a lower energy limit (1 keV for light ions and 5 MeV for HIs). Track energy below the limit was assumed to be locally deposited. For neutron tracks <20 MeV, kerma factors were used to obtain absorbed dose. Results are presented for a discrete set of angles of incidence on an ICRU tissue slab phantom. PMID:19887515

  13. Determining the Effects of EMIC Waves on Precipitating MeV Electrons during Strom Main Phases

    NASA Astrophysics Data System (ADS)

    Chen, Y.

    2015-12-01

    Theoretic studies have suggested that electromagnetic ion cyclotron (EMIC) waves can cause significant precipitation of ~MeV electrons, supposedly accounting for the fast dropouts of outer-belt electrons during storm main phases. Usually the resonance between left-hand polarized EMIC with electrons with moderate energy is unlikely due to their opposite polarizations, while resonance with highly relativistic electrons do occur and cause electrons to precipitate into the atmosphere through pitch-angle scattering. Several previous studies on observations find a close relation between the two phenomena, e.g., Cliverd et al. [2007], Sandanger et al. [2007], and Miyoshi et al. [2008], while others find otherwise, e.g., Meredith et al. [2011]; recently, more observational evidence supporting the connection has been reported (e.g., Li et al. [2014] and Blum et al. [2015]). However, whether and under what favoring conditions EMIC waves cause rapid dropouts of relativistic electrons during storm main phases remain unresolved questions. Here, using latest wave and electron data from multiple missions including Van Allen Probes, BARREL, and NOAA POES, we systemically examine the relation between EMIC waves and MeV electron precipitation. We first construct two independent event lists for intensified EMIC waves and enhancements of MeV electron precipitation, respectively. Then we cross check the two lists to identify if any significant correlation exists in between, and further characterize the wave effectiveness in terms of L-shell, MLT, resonance energy, as well as the background plasma conditions. Results from this study will advance our knowledge about the loss mechanism of outer-belt electrons, thus laying down another stepping stone towards high-fidelity physics-based models for radiation belts.

  14. Large scale silver nanowires network fabricated by MeV hydrogen (H+) ion beam irradiation

    NASA Astrophysics Data System (ADS)

    Honey, S.; Naseem, S.; Ishaq, A.; Maaza, M.; Bhatti, M. T.; Wan, D.

    2016-04-01

    A random two-dimensional large scale nano-network of silver nanowires (Ag-NWs) is fabricated by MeV hydrogen (H+) ion beam irradiation. Ag-NWs are irradiated under H+ ion beam at different ion fluences at room temperature. The Ag-NW network is fabricated by H+ ion beam-induced welding of Ag-NWs at intersecting positions. H+ ion beam induced welding is confirmed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Moreover, the structure of Ag NWs remains stable under H+ ion beam, and networks are optically transparent. Morphology also remains stable under H+ ion beam irradiation. No slicings or cuttings of Ag-NWs are observed under MeV H+ ion beam irradiation. The results exhibit that the formation of Ag-NW network proceeds through three steps: ion beam induced thermal spikes lead to the local heating of Ag-NWs, the formation of simple junctions on small scale, and the formation of a large scale network. This observation is useful for using Ag-NWs based devices in upper space where protons are abandoned in an energy range from MeV to GeV. This high-quality Ag-NW network can also be used as a transparent electrode for optoelectronics devices. Project supported by the National Research Foundation of South Africa (NRF), the French Centre National pour la Recherche Scientifique, iThemba-LABS, the UNESCO-UNISA Africa Chair in Nanosciences & Nanotechnology, the Third World Academy of Science (TWAS), Organization of Women in Science for the Developing World (OWSDW), the Abdus Salam ICTP via the Nanosciences African Network (NANOAFNET), and the Higher Education Commission (HEC) of Pakistan.

  15. The Spectrum of Isotropic Diffuse Gamma-Ray Emission Between 100 Mev and 820 Gev

    NASA Technical Reports Server (NTRS)

    Ackermann, M.; Ajello, M.; Albert, A.; Atwood, W. B.; Baldini, L.; Ballet, J.; Barbiellini, G.; Bastieri, D.; Brandt, T. J.; Hays, E.; Perkins, J. S.

    2014-01-01

    The gamma-ray sky can be decomposed into individually detected sources, diffuse emission attributed to the interactions of Galactic cosmic rays with gas and radiation fields, and a residual all-sky emission component commonly called the isotropic diffuse gamma-ray background (IGRB). The IGRB comprises all extragalactic emissions too faint or too diffuse to be resolved in a given survey, as well as any residual Galactic foregrounds that are approximately isotropic. The first IGRB measurement with the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope (Fermi) used 10 months of sky-survey data and considered an energy range between 200 MeV and 100 GeV. Improvements in event selection and characterization of cosmic-ray backgrounds, better understanding of the diffuse Galactic emission, and a longer data accumulation of 50 months, allow for a refinement and extension of the IGRB measurement with the LAT, now covering the energy range from 100 MeV to 820 GeV. The IGRB spectrum shows a significant high-energy cutoff feature, and can be well described over nearly four decades in energy by a power law with exponential cutoff having a spectral index of 2.32 plus or minus 0.02 and a break energy of (279 plus or minus 52) GeV using our baseline diffuse Galactic emission model. The total intensity attributed to the IGRB is (7.2 plus or minus 0.6) x 10(exp -6) cm(exp -2) s(exp -1) sr(exp -1) above 100 MeV, with an additional +15%/-30% systematic uncertainty due to the Galactic diffuse foregrounds.

  16. Neutron-neutron quasifree scattering in nd breakup at 10 MeV

    NASA Astrophysics Data System (ADS)

    Malone, R. C.; Crowe, B.; Crowell, A. S.; Cumberbatch, L. C.; Esterline, J. H.; Fallin, B. A.; Friesen, F. Q. L.; Han, Z.; Howell, C. R.; Markoff, D.; Ticehurst, D.; Tornow, W.; Witała, H.

    2016-03-01

    The neutron-deuteron (nd) breakup reaction provides a rich environment for testing theoretical models of the neutron-neutron (nn) interaction. Current theoretical predictions based on rigorous ab-initio calculations agree well with most experimental data for this system, but there remain a few notable discrepancies. The cross section for nn quasifree (QFS) scattering is one such anomaly. Two recent experiments reported cross sections for this particular nd breakup configuration that exceed theoretical calculations by almost 20% at incident neutron energies of 26 and 25 MeV [1, 2]. The theoretical values can be brought into agreement with these results by increasing the strength of the 1S0 nn potential matrix element by roughly 10%. However, this modification of the nn effective range parameter and/or the 1S0 scattering length causes substantial charge-symmetry breaking in the nucleon-nucleon force and suggests the possibility of a weakly bound di-neutron state [3]. We are conducting new measurements of the cross section for nn QFS in nd breakup. The measurements are performed at incident neutron beam energies below 20 MeV. The neutron beam is produced via the 2H(d, n)3He reaction. The target is a deuterated plastic cylinder. Our measurements utilize time-of-flight techniques with a pulsed neutron beam and detection of the two emitted neutrons in coincidence. A description of our initial measurements at 10 MeV for a single scattering angle will be presented along with preliminary results. Also, plans for measurements at other energies with broad angular coverage will be discussed.

  17. Extreme relativistic electron fluxes at geosynchronous orbit: Analysis of GOES E > 2 MeV electrons

    NASA Astrophysics Data System (ADS)

    Meredith, Nigel P.; Horne, Richard B.; Isles, John D.; Rodriguez, Juan V.

    2015-03-01

    Relativistic electrons (E > 1 MeV) cause internal charging on satellites and are an important space weather hazard. A key requirement in space weather research concerns extreme events and knowledge of the largest flux expected to be encountered over the lifetime of a satellite mission. This is interesting both from scientific and practical points of view since satellite operators, engineers, and the insurance industry need this information to better evaluate the effects of extreme events on their spacecraft. Here we conduct an extreme value analysis of daily averaged E > 2 MeV electron fluxes from the Geostationary Operational Environmental Satellites (GOES) during the 19.5 year period from 1 January 1995 to 30 June 2014. We find that the daily averaged flux measured at GOES West is typically a factor of about 2.5 higher than that measured at GOES East, and we conduct independent analyses for these two locations. The 1 in 10, 1 in 50, and 1 in 100 year daily averaged E > 2 MeV electron fluxes at GOES West are 1.84 ×105, 5.00 ×105, and 7.68 ×105 cm-2 s-1 sr-1, respectively. The corresponding fluxes at GOES East are 6.53 ×104, 1.98 ×105, and 3.25 ×105 cm-2 s-1 sr-1, respectively. The largest fluxes seen during the 19.5 year period on 29 July 2004 were particularly extreme and were seen by satellites at GOES West and GOES East. The extreme value analysis suggests that this event was a 1 in 50 year event.

  18. Response of a diamond detector sandwich to 14 MeV neutrons

    NASA Astrophysics Data System (ADS)

    Osipenko, M.; Ripani, M.; Ricco, G.; Caiffi, B.; Pompili, F.; Pillon, M.; Verona-Rinati, G.; Cardarelli, R.

    2016-05-01

    In this paper we present the measurement of the response of 50 μm thin diamond detectors to 14 MeV neutrons. Such neutrons are produced in fusion reactors and are of particular interest for ITER neutron diagnostics. Among semiconductor detectors diamond has properties most appropriate for harsh radiation and temperature conditions of a fusion reactor. However, 300-500 μm thick diamond detectors suffer significant radiation damage already at neutron fluences of the order of 1014 n/cm2. It is expected that a 50 μm thick diamond will withstand a fluence of >1016 n /cm2. We tested two 50 μm thick single crystal CVD diamonds, stacked to form a "sandwich" detector for coincidence measurements. The coincidence between two diamonds allows to suppress background and increase detection efficiency. The detector measured the conversion of 14 MeV neutrons, impinging on one diamond, into α particles which were detected in the second diamond in coincidence with nuclear recoil. For 12C(n , α)9Be reaction the total energy deposited in the detector gives access to the initial neutron energy value. The measured 14 MeV neutron detection sensitivity through this reaction by a detector of an effective area 3×3 mm2 was 5 ×10-7 counts cm2/n. This value is in good agreement with Geant4 simulations. The energy resolution of the detector was found to be 870 keV FWHM, but according to Geant4 simulations only about 160 keV FWHM were intrinsic.

  19. Carcinoma of the cervix: surgical staging and radiotherapy with 32 MeV Betatron

    SciTech Connect

    Shah, K.; Olson, M.H.; Dillard, E.A.

    1982-09-01

    Fifty-six patients with squamous cell carcinoma of the cervix were staged by exploratory laparotomy. Twenty-eight of them received radiotherapy with 32 MeV Betatron and intracavitary radium. Twenty-one patients with Stage IB or IIA had a radical hysterectomy, five had post-operative pelvic irradiation, and two had primary exenteration. An overall 23.2% of patients had metastases in the paraaortic fields. Four patients with paraaortic node disease received extended field irradiation: 4500 rad in 5 weeks to paraaortic nodes. Two of them are alive and disease-free at 5.5 to 6.5 years.

  20. The Gent University 15 MeV high-current linear electron accelerator facility

    NASA Astrophysics Data System (ADS)

    Mondelaers, W.; Van Laere, K.; Goedefroot, A.; Van den Bossche, K.

    1996-01-01

    The Gent University 15 MeV 20kW linear electron accelerator facility was initially designed for fundamental nuclear physics research. During the last years a large effort has been devoted to the expansion of the range of machine applications in view of a new extensive experimental programme in the fields of atomic and solid-state physics, biomaterials research, polymer chemistry, space research, food technology, high-dose dosimetry and radiation therapy. The accelerator facility in its present configuration, the peripheral equipment and the experimental programme are described with emphasis on the original features.