Sample records for 10-600 kev energy

  1. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY...ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600...

  2. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY...ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600...

  3. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY...ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600...

  4. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY...ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600...

  5. Energy loss distribution of 100 keV H+ in thin carbon films

    Microsoft Academic Search

    Noriaki Matsunami; Kenshin Kitoh

    1992-01-01

    The energy loss of ~100 keV H+ transmitted through thin carbon films of thickness in the range 6-20 nm has been measured with an energy resolution of ~ 20 eV. We have observed new energy loss peaks around 210 and 400 eV in addition to the normal energy loss peak around 1 keV for the thinner film of ~ 7

  6. Characterization of the PILATUS photon-counting pixel detector for X-ray energies from 1.75 keV to 60 keV

    NASA Astrophysics Data System (ADS)

    Donath, T.; Brandstetter, S.; Cibik, L.; Commichau, S.; Hofer, P.; Krumrey, M.; Lüthi, B.; Marggraf, S.; Müller, P.; Schneebeli, M.; Schulze-Briese, C.; Wernecke, J.

    2013-03-01

    The PILATUS detector module was characterized in the PTB laboratory at BESSY II comparing modules with 320 ?m thick and newly developed 450 ?m and 1000 ?m thick silicon sensors. Measurements were carried out over a wide energy range, in-vacuum from 1.75 keV to 8.8 keV and in air from 8 keV to 60 keV. The quantum efficiency (QE) was measured as a function of energy and the spatial resolution was measured at several photon energies both in terms of the modulation transfer function (MTF) from edge profile measurements and by directly measuring the point spread function (PSF) of a single pixel in a raster scan with a pinhole beam. Independent of the sensor thickness, the measured MTF and PSF come close to those for an ideal pixel detector with the pixel size of the PILATUS detector (172 × 172 ?m2). The measured QE follows the values predicted by calculation. Thicker sensors significantly enhance the QE of the PILATUS detectors for energies above 10 keV without impairing the spatial resolution and noise-free detection. In-vacuum operation of the PILATUS detector is possible at energies as low as 1.75 keV.

  7. Nowcast Model for Low Energy Electrons (10-200 keV) in the Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Ganushkina, N. Y.; Pitchford, D. A.; Welling, D. T.; Heynderickx, D.

    2014-12-01

    We present the nowcast model for low energy (< 200 keV) electrons in the inner magnetosphere, operating online under the SPACECAST project (http://fp7-spacecast.eu) which is the version of the Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM) for electrons. Low energy electron fluxes are very important to specify when hazardous satellite surface charging phenomena are considered. The presented model provides the low energy electron flux at all L-shells and at all satellite orbits, when necessary. The model is driven by the real time solar wind and Interplanetary Magnetic Field (IMF) parameters with 1 hour time shift for propagation to the Earth's magnetopause, and by the real time Dst index. Real time geostationary GOES 13 or GOES 15 (whenever which available) data on electron fluxes in three energies, such as 40 keV, 75 keV, 150 keV, are used for comparison and validation of IMPTAM running online. On average, the model provides very good agreement with the data, the basic level of the observed fluxes is very well reproduced. The best agreement between the modeled and the observed fluxes are found for <100 keV electrons. At the same time, not all the peaks and dropouts in the observed electron fluxes are reproduced. For 150 keV electrons, the modeled fluxes are often smaller than the observed ones by an order of magnitude. We estimate the The Normalized Root-Mean-Square Deviation (NRMSD), compute the binary event tables for 1 hour window to reveal the model hit rates and Heidke Skill Scores. This is the first attempt to model low energy electrons in real time at 10 minutes resolution. The output of this model can serve as an input of electron seed population for the higher-energy radiation belt modeling.

  8. Surface damage studies of ETFE polymer bombarded with low energy Si ions (?100 keV)

    NASA Astrophysics Data System (ADS)

    Minamisawa, Renato Amaral; De Almeida, Adelaide; Budak, Satilmis; Abidzina, Volha; Ila, Daryush

    2007-08-01

    Surface studies of ethylenetetrafluoroethylene (ETFE), bombarded with Si in a high-energy tandem Pelletron accelerator, have recently been reported. Si ion bombardment with a few MeV to a few hundred keV energies was shown to be sufficient to produce damage on ETFE film. We report here the use of a low energy implanter with Si ion energies lower than 100 keV, to induce changes on ETFE films. In order to determine the radiation damage, ETFE bombarded films were simulated with SRIM software and analyzed with optical absorption photometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy to show quantitatively the physical and chemical property changes. Carbonization occurs following higher dose implantation, and hydroperoxides were formed following dehydroflorination of the polymer.

  9. Study of the Ar LMM spectra by He + projectile at 1250 keV, 1500 keV and 2000 keV bombardment energies

    NASA Astrophysics Data System (ADS)

    Tóth, L.; Víkor, Gy.; Ricz, S.; Pelicon, P.; Miller, R.

    1994-03-01

    The influence of He + ion impact on the Ar LMM spectra was investigated at the ESA-21 electron spectrometer using three different ion energies. Observed line relative energies to the L 3M 2,3( 1D 2) line agree well with other results, but the relative intensities of five angular-isotropic lines deviate significantly from other measurements and theory. The angular dependence of energy shifts agrees with the quantum PCI theory of Barrachina and Macek, except for directions close to 180°, where a slight enhancement of energy shift was observed. Finally, the angular distributions of the L 2M 2,3( 1S 0), ( 1d 2) and ( 3P 0,1,2) line intensities were compared to the alignment theory of Sizov and Kabachnik.

  10. A multi-energy (2-60 keV) calibration of 200 ? m and 400 ?m diameter spectroscopic GaAs X-ray photodiodes

    NASA Astrophysics Data System (ADS)

    Barnett, A. M.; Lees, J. E.; Bassford, D. J.

    2013-09-01

    Thin (2 ?m active layer) spectroscopic p+-i-n+ GaAs X-ray photodiodes of circular mesa geometry (200 ?m and 400 ?m diameter; one representative diode of each diameter) have been characterised for their energy response using high-purity X-ray fluorescence calibration samples excited by an X-ray tube, giving energies between 2.1 keV (Au M?1) and 21.18 keV (Pd K?1), and an 241Am radioisotope ?-ray source (26.3 keV, 59.5 keV). The photodiodes were operated uncooled at +33°C. The 200 ?m diameter device's energy resolution (FWHM) was found to be constant (0.79 keV) and primarily limited by electronics noise at energies between 2.1 keV and 21.18 keV, but it broadened to 0.85 keV at 26.3 keV, and to 1 keV at 59.5 keV. The 400 ?m diameter device's energy resolution (FWHM) was constant (1.1 keV) for photon energies between 4.95 keV and 9.89 keV, but increased to 1.15 keV at 16.62 keV, 1.25 keV at 21.18 keV, 1.3 keV at 26.3 keV and 1.66 keV at 59.5 keV. The broadening of energy resolution (FWHM) observed in both cases is greater than can be attributed solely to increasing Fano noise and is hypothesised to be at least in part due to energy dependent charge trapping. However, for both types of device, the peak charge output from the devices was found to be linearly (R2 >= 0.9999) dependent on incident X-ray energy.

  11. Multilayer optics for monochromatic high-resolution X-ray imaging diagnostic in a broad photon energy range from 2 keV to 22 keV

    NASA Astrophysics Data System (ADS)

    Troussel, Ph.; Dennetiere, D.; Maroni, R.; Høghøj, P.; Hedacq, S.; Cibik, L.; Krumrey, M.

    2014-12-01

    The "Commissariat à l'énergie atomique et aux énergies alternatives" (CEA) studies and designs advanced X-ray diagnostics to probe dense plasmas produced at the future Laser MegaJoule (LMJ) facility. Mainly for X-ray imaging with high spatial resolution, different types of multilayer mirrors were developed to provide broadband X-ray reflectance at grazing incidence. These coatings are deposited on two toroidal mirror substrates that are then mounted into a Wolter-type geometry (working at a grazing angle of 0.45°) to realize an X-ray microscope. Non-periodic (depth graded) W/Si multilayer can be used in the broad photon energy range from 2 keV to 22 keV. A third flat mirror can be added for the spectral selection of the microscope. This mirror is coated with a Mo/Si multilayer for which the d-spacing varies in the longitudinal direction to satisfy the Bragg condition within the angular acceptance of the microscope and also to compensate the angular dispersion due to the field of the microscope. We present a study of such a so-called Göbel mirror which was optimized for photon energy of 10.35 keV. The three mirrors were coated using magnetron sputtering technology by Xenocs SA. The reflectance in the entire photon energy range was determined in the laboratory of the Physikalisch-Technische Bundesanstalt (PTB) at the synchrotron radiation facility BESSY II in Berlin.

  12. Gamma Ray Attenuation Coefficient Measurement in Energies 1172 keV and 1332 keV for Neutron Absorbent Saturated Solutions

    SciTech Connect

    Jalali, Majid [Esfahan Nuclear Technology Center - ENTC (Iran, Islamic Republic of)

    2006-07-01

    The compounds, Na{sub 2}B{sub 4}O{sub 7}, H{sub 3}BO{sub 3}, CdCl{sub 2} and NaCl and their solutions, attenuate gamma rays in addition to neutron absorption. These compounds are widely used in shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to saturated solutions of the above four compounds, in energies 1172 keV and 1332 keV have been measured by NaI detector and agree very well with the results obtained by Xcom code. Experiment and computation show that, H{sub 3}BO{sub 3} has the highest gamma ray attenuation coefficient among the aforementioned compounds. (author)

  13. Efficiency of Scintillator Materials in the Energy Range 8.0-32.0 keV

    SciTech Connect

    Kinney, J H; Haupt, D L

    2002-07-01

    X-ray microtomography requires the measurement of x-ray attenuation along ray paths through a specimen, and on the inversion of these data to obtain a spatially resolved mapping of the microstructure of the specimen. To do this efficiently, two-dimensional array detectors are often used to measure the transmitted x-rays by capturing and recording each x-ray incident on the detector. The highest resolution CT instruments perform this by converting the incident x-rays to visible light, and then focusing this light onto a charge-coupled-device (CCD) detector. The light output of the scintillator (photons per incident x-ray), the numerical aperture of the optical lens system, and the quantum efficiency of the CCD govern the efficiency of the detection process. Several years earlier, our group performed an investigation aimed at determining the best scintillator material for high-resolution synchrotron CT. The selection criteria included light output in the 8-32 keV energy range, the spatial resolution of the scintillator, the wavelength of the scintillation radiation, and the stability and ease of polishing of the scintillator. A list of the scintillators that we considered, with the exceptions of the more recently developed glass scintillators, is provided in Table 1. Among these scintillators, we concluded that single crystal cadmium tungstate was optimum; we have used this material in all subsequent synchrotron CT systems. Since this original study, several doped-glass scintillators have become available. The LSO (Lu orthosilicates) scintillators, developed for PET scanning, show considerable light output at high energy (energies above 500 keV). Theoretically, the light output of these scintillators should be twice that of the cadmium tungstate. The purpose of this study was to determine the efficiency of two such scintillators (LSO:Yt and IQI-401 high density terbium activated glass) in the energy range from 8-32 keV.

  14. Energy and position resolution of germanium microstrip detectors at X-ray energies 15 to 100 keV

    Microsoft Academic Search

    G. Rossi; J. Morse; D. Protic

    1997-01-01

    Germanium offers superior energy and position resolution compared to silicon for the detection of X-rays at energies between 15 and 100 keV. We have characterised 200 ?m strip pitch detectors fabricated by two different processes. By scanning a 10 ?m wide monochromatic synchrotron X-ray beam across the detectors, measurements were made on both spectral energy response and spatial resolution. Charge

  15. Monochromator harmonic content measurements and calculations at energies above 20 keV

    SciTech Connect

    Chapman, D.; Moulin, H.; Garrett, R.F.

    1991-01-01

    Measurements of the harmonic content from single and double crystal silicon monochromators have been made in the 20 to 100 keV at the X17 Superconducting Wiggler Beamline at the NSLS. These measurements are compared with calculations which estimate the monochromatic beam harmonic content and the detection system efficiency with good agreement. At high photon energies ( > 20keV), the scattering of x-rays from an amorphous scatterer is dominated by the inelastic Compton process. At large scattering angles this will completely overwhelm the more forward directed elastic scattering. The Compton x-ray energy shift is large enough to make the distinction between elastic and Compton scattering unambiguous when a spectrum is acquired with a solid state detector. This shift, which is energy dependent, allows the measurement of the relative harmonic intensity in a way that is not affected by pulse pileup in the detector and electronics. The present measurements were done to assess the level of harmonic contamination from two monochromator systems both used on the X17 beamline: the single crystal type monochromator for the Digital Subtraction Coronary Angiography project; and the double crystal monochromator being developed for the Multiple Energy Computed Tomography (MECT) project and the Materials Science program. 5 refs.

  16. Hydrogen-Atom Excitation and Ionization by Proton Impact in 50-Kev to 200-Kev Energy Region 

    E-print Network

    Fitchard, E.; Ford, A. Lewis; Reading, John F.

    1977-01-01

    &M University, College Station, Texas 77843 (Received 28 December 1976) We report results for n = 2 and n = 3 excitation and ionization in proton-hydrogen collisions. The calculations use a single-center {target) basis with s, p, and d angular momentum states... important, and at still lower energies an expan- sion in H,' adiabatic molecular states is the most appropriate. The most successful calculations for excitation to the n = 2 levels in the present en- ergy region have perhaps been close-coupling cal...

  17. Extension to Low Energies (<7keV) of High Pressure X-Ray Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Itié, J.-P.; Flank, A.-M.; Lagarde, P.; Polian, A.; Couzinet, B.; Idir, M.

    2007-01-01

    High pressure x-ray absorption has been performed down to 3.6 keV, thanks to the new LUCIA beamline (SLS, PSI) and to the use of perforated diamonds or Be gasket. Various experimental geometries are proposed, depending on the energy of the edge and on the concentration of the studied element. A few examples will be presented: BaTiO3 at the titanium K edge, Zn0.95 Mn0.05O at the manganese K edge, KCl at the potassium K edge.

  18. Neutron Total Cross Sections of {sup 235}U From Transmission Measurements in the Energy Range 2 keV to 300 keV and Statistical Model Analysis of the Data

    SciTech Connect

    Derrien, H.; Harvey, J.A.; Larson, N.M.; Leal, L.C.; Wright, R.Q.

    2000-05-01

    The average {sup 235}U neutron total cross sections were obtained in the energy range 2 keV to 330 keV from high-resolution transmission measurements of a 0.033 atom/b sample.1 The experimental data were corrected for the contribution of isotope impurities and for resonance self-shielding effects in the sample. The results are in very good agreement with the experimental data of Poenitz et al.4 in the energy range 40 keV to 330 keV and are the only available accurate experimental data in the energy range 2 keV to 40 keV. ENDF/B-VI evaluated data are 1.7% larger. The SAMMY/FITACS code 2 was used for a statistical model analysis of the total cross section, selected fission cross sections and data in the energy range 2 keV to 200 keV. SAMMY/FITACS is an extended version of SAMMY which allows consistent analysis of the experimental data in the resolved and unresolved resonance region. The Reich-Moore resonance parameters were obtained 3 from a SAMMY Bayesian fits of high resolution experimental neutron transmission and partial cross section data below 2.25 keV, and the corresponding average parameters and covariance data were used in the present work as input for the statistical model analysis of the high energy range of the experimental data. The result of the analysis shows that the average resonance parameters obtained from the analysis of the unresolved resonance region are consistent with those obtained in the resolved energy region. Another important result is that ENDF/B-VI capture cross section could be too small by more than 10% in the energy range 10 keV to 200 keV.

  19. Cross section for U 233 and U 235 fission by neutrons with energies between 3 and 800 Kev

    Microsoft Academic Search

    G. V. Gorlov; B. M. Gokhberg; V. M. Morozov; G. A. Otroshchenko; V. A. Shigin

    1960-01-01

    The fission cross sections for fission of U233 and U235 by neutrons with energies between 3 and 800 Kev have been measured. The neutrons were obtained from a van de Graaff generator using the reaction T(p,n)He3. When the neutron energy is varied between 3.4 and 780 Kev the fission cross section drops from 7.5 to 1.9 barns for U233 and

  20. Energy and position resolution of germanium microstrip detectors at x-ray energies from 15 to 100 keV

    SciTech Connect

    Rossi, G.; Morse, J. (European Synchrotron Radiation Facility, Grenoble (France)); Protic, D. (Forschungszentrum Juelich GmbH (Germany). Inst. fuer Kernphysik)

    1999-06-01

    In addition to their far greater X-ray detection efficiency, germanium strip detectors offer superior energy and position resolution as compared to those fabricated of silicon for energies in the range of 15 to 100 keV. The authors have characterized 200-[micro]m strip pitch detectors fabricated by two different processes. By scanning a 10-[micro]m-wide monochromatic synchrotron X-ray beam across these detectors, measurements were made on both spectral energy response and spatial resolution. X rays absorbed between neighboring diode strips suffer from charge diffusion splitting of their signals which seriously degrades the detector performance, but by reconstructing events using an energy-sum coincidence algorithm the authors succeeded in producing artifact-free spectra with energy resolution <2 keV, peak/valley ratios > 1000, and count uniformities across the detector surface <1.5% for energies below 60 keV. The experimentally measured energy spectra show remarkable agreement with those predicted by computer simulation, in which the EGS4 code for photon absorption is combined with a simple algorithm to account for charge diffusion.

  1. Electron Transfer in p-Ar Collisions at keV Energies

    SciTech Connect

    Alarcon, F. B. [Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70542, 04510 Coyoacan, Mexico, D.F. (Mexico); Martinez, H. [Instituto de Ciencias Fisicas, Universidad Nacional Autonoma de Mexico, Apartado postal 48-3, 62210, Cuernavaca, Morelos (Mexico); Castillo, F. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico (Mexico)

    2009-03-10

    Absolute differential and total cross sections for single electron capture of H{sup +} ions impinging on Ar atoms in the energy range of 0.5-5.0 keV and scattering angles from -5.0 deg. to 5.0 deg. are reported. The absolute differential cross (DCS) sections for all acceleration energies shows a decreasing behavior with increasing angle, showing an overall decrease of six orders of magnitude. The total cross section is found to be between the range of 4.9 and 15 A{sup 2}. The total cross sections display an increasing behavior as a function of the incident energy. The absolute differential and total cross section are compared with other available measurements and a recent theoretical approach.

  2. The Reuven Ramaty High Energy Solar Spectroscopic Imager observation of the 1809 keV line from Galactic 26Al

    E-print Network

    David M. Smith

    2003-04-28

    Observations of the central radian of the Galaxy by the Reuven Ramaty High Energy Solar Spectroscopy Imager (RHESSI) have yielded a high-resolution measurement of the 1809 keV line from 26Al, detected at 11 sigma significance in nine months of data. The RHESSI result for the width of the cosmic line is 2.03 (+0.78, -1.21) keV FWHM. The best fit line width of 5.4 keV FWHM reported by Naya et al. (1996) using the Gamma-Ray Imaging Spectrometer (GRIS) balloon instrument is rejected with high confidence.

  3. FHBS calculation of ionized electron angular and energy distribution following the p+H collision at 20 keV 

    E-print Network

    Fu, Jun

    2004-11-15

    than 0:5% for 20 keV projectile energy and less than 2% for 48 keV projectile energy after h partial waves are included. Table II. Total Cross Sections from Two B1 Methods s-d s-f s-g s-h All-Partial Wave 20 keV 1.95 2.06 2.09 2.10 2.11 48 keV 1.69 1...- ing angles, but not reliable at large backward scattering angles. 27 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 20 40 60 80 100 120 140 160 180 ds/dq (10 -16 cm 2 /degree) Angle (degree) s-d s-f s-h All Fig. 1. Angular distribution of electrons at 20 ke...

  4. Comparison of TOF-ERDA and nuclear resonance reaction techniques for range profile measurements of keV energy implants

    Microsoft Academic Search

    J. Jokinen; J. Keinonen; P. Tikkanen; A. Kuronen; T. Ahlgren; K. Nordlund

    1996-01-01

    A comparative study on the range measurements of keV energy implants by the Time-of-Flight Elastic Recoil Detection Analysis (TOF-ERDA) and conventionally used nuclear resonance reaction methods has been performed for 20–100 keV 15N+ ions implanted into crystalline silicon. Range profiles of 15N atoms were chosen because they can be measured accurately using a very strong and narrow resonance at Ep

  5. Optical constants for hard x-ray multilayers over the energy range E = 35 180 keV

    E-print Network

    of a prototype W/SiC multilayer coating over the energy range E=35 ­ 100 keV, and we compare the measured, W, Pt, C, B4C, Si and SiC were deposited by magnetron sputtering onto superpolished optical flats the reflectance of prototype hard X-ray W/Si and W/SiC multilayers designed for use above 100 keV; we found

  6. High Spatial Resolution STXM at 6.2 keV Photon Energy

    NASA Astrophysics Data System (ADS)

    Vila-Comamala, Joan; Dierolf, Martin; Kewish, Cameron M.; Thibault, Pierre; Pilvi, Tero; Färm, Elina; Guzenko, Vitaliy; Gorelick, Sergey; Menzel, Andreas; Bunk, Oliver; Ritala, Mikko; Pfeiffer, Franz; David, Christian

    2010-04-01

    We report on a zone-doubling technique that bypasses the electron-beam lithography limitations for the production of X-ray diffractive optics and enables the fabrication of Fresnel zone plates with smaller outermost zone widths than other well-established approaches. We have applied this method to manufacture hard X-ray Fresnel zone plates with outermost zone widths of 25 and 20 nm. These lenses have been tested in scanning transmission X-ray microscopy (STXM) at energies up to 6.2 keV, producing images of test structures that demonstrate a spatial resolution of 25 nm. High spatial resolution STXM images of several biological specimens have been acquired in transmission, dark-field and differential phase contrast modes.

  7. High Spatial Resolution STXM at 6.2 keV Photon Energy

    SciTech Connect

    Vila-Comamala, Joan; Kewish, Cameron M.; Thibault, Pierre; Guzenko, Vitaliy; Gorelick, Sergey; Menzel, Andreas; Bunk, Oliver; David, Christian [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Dierolf, Martin; Pfeiffer, Franz [Technische Universitaet Muenchen, D-85748 Garching (Germany); Pilvi, Tero; Faerm, Elina; Ritala, Mikko [Department of Chemistry, FI-00014 University of Helsinki (Finland)

    2010-04-06

    We report on a zone-doubling technique that bypasses the electron-beam lithography limitations for the production of X-ray diffractive optics and enables the fabrication of Fresnel zone plates with smaller outermost zone widths than other well-established approaches. We have applied this method to manufacture hard X-ray Fresnel zone plates with outermost zone widths of 25 and 20 nm. These lenses have been tested in scanning transmission X-ray microscopy (STXM) at energies up to 6.2 keV, producing images of test structures that demonstrate a spatial resolution of 25 nm. High spatial resolution STXM images of several biological specimens have been acquired in transmission, dark-field and differential phase contrast modes.

  8. Monte Carlo calculations of energy deposition distributions of electrons below 20 keV in protein.

    PubMed

    Tan, Zhenyu; Liu, Wei

    2014-05-01

    The distributions of energy depositions of electrons in semi-infinite bulk protein and the radial dose distributions of point-isotropic mono-energetic electron sources [i.e., the so-called dose point kernel (DPK)] in protein have been systematically calculated in the energy range below 20 keV, based on Monte Carlo methods. The ranges of electrons have been evaluated by extrapolating two calculated distributions, respectively, and the evaluated ranges of electrons are compared with the electron mean path length in protein which has been calculated by using electron inelastic cross sections described in this work in the continuous-slowing-down approximation. It has been found that for a given energy, the electron mean path length is smaller than the electron range evaluated from DPK, but it is large compared to the electron range obtained from the energy deposition distributions of electrons in semi-infinite bulk protein. The energy dependences of the extrapolated electron ranges based on the two investigated distributions are given, respectively, in a power-law form. In addition, the DPK in protein has also been compared with that in liquid water. An evident difference between the two DPKs is observed. The calculations presented in this work may be useful in studies of radiation effects on proteins. PMID:24519325

  9. FHBS calculation of ionized electron angular and energy distribution following the p+H collision at 20 keV

    E-print Network

    Fu, Jun

    2004-11-15

    A Finite Hilbert Basis Set (FHBS) method to calculate the angular and energy distribution of ejected electrons in an ion-atom collision is presented. This method has been applied to the p + H collision at 20 keV impact energy. An interference effect...

  10. He+O{sup 2} collisions at low keV energies

    SciTech Connect

    Heckman, V.R.; Quintana, E.J.; Perry, D.M.; Pollack, E. [Univ. of Connecticut, Storrs, CT (United States)

    1996-05-01

    The direct scattering in He{sup 0}+O{sub 2} collisions is studied at low keV energies and scattering angles 0<{theta}<2 deg. Time-of-flight techniques are used to identify the states excited. The experimental techniques have previously been described. To date the authors have reported on H{sup 0}+N{sub 2} collisions and also on H{sup 0}+H{sub 2} and O{sub 2}. A striking characteristic of the H{sup 0} collisions is the weakness of the electronically elastic channel even at the smallest scattering angles. In He+O{sub 2} the authors find elastic scattering to be the dominant small angle process. The probability of electronically elastic scattering is greater than 0.5 at angles less than 1.0 deg and falls to 0.1 at 2.0 deg. The spectra show an inelastic peak at a 6 eV energy loss which is attributed to He+O{sub 2} {yields} He+O{sub 2}* {yields} He+O({sup 3}P) + O({sup 3}P). A broad structure with a maximum near 16 eV is seen at larger angles and is attributed in part to excitation resulting in dissociating states of O{sub 2}. Excitation of the He is found to be at the energies and angles studied. Additional results will be presented and interpreted.

  11. Presence of a soft excess between 0.6 keV and 0.9 keV in the energy spectrum of Cir X-1

    NASA Astrophysics Data System (ADS)

    Spanò, M.; Iaria, R.; di Salvo, T.; Robba, N. R.; Burderi, L.; Stella, L.; Frontera, F.; van der Klis, M.

    2004-06-01

    We report on the results of a new BeppoSAX (0.12-200 keV) observation of the peculiar X-ray binary source Circinus X-1 (Cir X-1) near the apastron. We produced a color-color diagram and selected seven different zones. We fitted the spectra obtained from each zone using a model consisting of a blackbody component, at a temperature of ~0.5 keV, and a Comptonized component, with a seed-photon temperature of ~1 keV, electron temperature of ~2.7 keV and optical depth of ~11. A soft excess between 0.6 keV and 0.9 keV is present in four out of the seven extracted spectra. To fit the soft excess we tried several continuum emission models, and we find good results only adding a further blackbody component absorbed by a different equivalent hydrogen column, an order of magnitude lower than the absorption of the other two components; its physical interpretation is however hard to address.

  12. Isotopic Mo Neutron Total Cross Section Measurements in the Energy Range 1 to 620 keV

    NASA Astrophysics Data System (ADS)

    Bahran, R.; Barry, D.; Leinweber, G.; Rapp, M.; Block, R.; Daskalakis, A.; McDermott, B.; Piela, S.; Blain, E.; Danon, Y.

    2014-05-01

    A series of new total cross section measurements for the stable molybdenum isotopes of 92,94,95,96,98,100Mo covering the energy range between 1 keV and 620 keV was performed at the Gaerttner LINAC Center at Rensselaer Polytechnic Institute. New high-accuracy resonance parameters were extracted from an analysis of the data using the multilevel R-matrix Bayesian code SAMMY. In the unresolved resonance region, average resonance parameters and fits to the total cross sections were obtained using the Bayesian Hauser-Feshbach statistical model code FITACS.

  13. Dosimetric prerequisites for routine clinical use of photon emitting brachytherapy sources with average energy higher than 50 kev

    Microsoft Academic Search

    Jeffrey F. Williamson; Ronald S. Sloboda; Mark J. Rivard; Jose Perez-Calatayud; Ali S. Meigooni; Geoffrey S. Ibbott; Larry A. De Werd; Rupak K. Das; Li Zuofeng

    2007-01-01

    This paper presents the recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Therapeutic Radiology and Oncology (ESTRO) on the dosimetric parameters to be characterized, and dosimetric studies to be performed to obtain them, for brachytherapy sources with average energy higher than 50 keV that are intended for routine clinical use. In addition, this

  14. High-energy behavior of the double photoionization of helium from 2 to 12 keV

    NASA Astrophysics Data System (ADS)

    Levin, J. C.; Sellin, I. A.; Johnson, B. M.; Lindle, D. W.; Miller, R. D.; Berrah, N.; Azuma, Y.; Berry, H. G.; Lee, D.-H.

    1993-01-01

    We report the ratio of double-to-single photoionization of He at several photon energies from 2 to 12 keV. By time-of-flight methods, we find a ratio consistent with an asymptote at 1.5%+/-0.2%, essentially reached by h?~=4 keV. Fair agreement is obtained with older shake calculations of Byron and Joachain [Phys. Rev. 164, 1 (1967)], of Åberg [Phys. Rev. A 2, 1726 (1970)], and with recent many-body perturbation theory (MBPT) of Ishihara, Hino, and McGuire [Phys. Rev. A 44, 6980 (1991)]. The result lies below earlier MPBT calculations by Amusia et al. [J. Phys. B 8, 1248 (1975)] (2.3%), and well above semiempirical predictions of Samson [Phys. Rev. Lett. 65, 2861 (1990)], who expects no asymptote and predicts ?(He2+)/?(He+)=0.3% at 12 keV.

  15. Experimental investigation of ?130 keV kinetic energy antiprotons annihilation on nuclei

    NASA Astrophysics Data System (ADS)

    Aghai-Khozani, H.; Barna, D.; Corradini, M.; Hayano, R.; Hori, M.; Kobayashi, T.; Leali, M.; Lodi-Rizzini, E.; Mascagna, V.; Prest, M.; Soter, A.; Todoroki, K.; Vallazza, E.; Venturelli, L.; Zurlo, N.

    2014-04-01

    The study of the antiproton ( bar {p}) annihilation cross section on nuclei at low energies (eV-MeV region) has implications for fundamental cosmology as well as for nuclear physics. Concerning the former, different models try to explain the matter/antimatter asymmetry in the universe assuming the existence of the so-called "islands" where antinucleon-nucleon annihilations occur in the border region (Cohen et al. Astrophys. J. 495, 539-549, 1998), while, from the nuclear physics point of view, the annihilation process is a valuable tool to evaluate the neutron/proton ratio in order to probe the external region of the nucleus (Gupta et al. Nucl. Phys. B 70(3), 414-424, 1974). The existing data of antinucleon-nucleon (or -nucleus) annihilation cross-sections are mainly confined to energies above ?1 MeV, while the cross section measured at LEAR in the 80's-90's (mostly with light targets Agnello et al. Phys. Lett. B 256, 349-353, 1991; Bertin et al. Phys. Lett. B 369, 77-85, 1996; Bertin et al. Phys. Lett. B 414, 220-228, 1997; Zenoni et al. Phys. Lett. B 461, 405-412, 1999; Bianconi et al. Phys. Lett. B 481, 194-198, 2000; Bianconi et al. Phys. Lett. B 492, 254-258, 2000) showed an unexpected behaviour for energies below 1 MeV (Bianconi et al. Phys. Lett. B 483, 353-359, 2000; Bianconi et al. Phys. Rev. C 62, 014611-7, 2000; Batty et al. Nucl. Phys. A 689, 721-740, 2001). The results showed a saturation with the atomic mass number against the A 2/3 trend which is observed for higher energies (being A the target mass number). The ASACUSA collaboration at CERN recently measured antiproton annihilation cross section on different kinds of nuclei with a bar {p} kinetic energy of 5.3 MeV (Bianconi et al. Phys. Lett. B 704, 461-466, 2011; Corradini et al. Nucl. Instr. Methods A 711, 12-20, 2013). Such results proved compatibility with the black-disk model with the Coulomb correction. But till now experimental difficulties prevented the investigation at energies below ?1 MeV. In 2012, the 100 keV region has been investigated for the first time (Aghai-Khozani et al. Eur. Phys. J. Plus 127, 125-128, 2012). We present here the first preliminary results of this experiment.

  16. Impact-parameter dependence of energy loss for 625keV H+ ions in Si single crystals

    Microsoft Academic Search

    A. Dygo; M. A. Boshart; L. E. Seiberling; N. M. Kabachnik

    1994-01-01

    The energy distributions for 625-keV H+ ions transmitted through thin Si single crystals are studied for detailed angular scans through the and axial as well as the \\\\{111\\\\} and \\\\{110\\\\} planar channels. Well-resolved structures in the distributions taken near the axial direction are observed. The experimental energy-loss distributions are very well reproduced by a Monte Carlo simulation using the semiclassical

  17. Analysis of experimental data on neutron-proton scattering in the energy range between 0 and 150 keV

    NASA Astrophysics Data System (ADS)

    Babenko, V. A.; Petrov, N. M.

    2009-04-01

    Experimental data on neutron-proton scattering in the energy range between 0 and 150 keV are analyzed by using various sets of effective-range parameters. It is shown that, in contrast to the parameters corresponding to the phase shifts of a Nijmegen group, the parameters corresponding to the experimental phase shifts reported by a group from George Washington University (GWU group) lead to very good agreement between the calculated cross sections and their experimental counterparts in the energy region under consideration. On the basis of the experimental value of the cross section for neutron—proton scattering at an energy of 2 keV, the total cross section for neutron-proton scattering at zero energy was found to be ? 0 = 20.428(16) b, which is in very good agreement with a value of ? 0 = 20.423(9) b, which was obtained as the weighted mean of the cross sections presented by Houke and Hurst. It is shown that, in the energy region around several tens of keV units, the effective-range parameters matched with Dilg’s cross-section value of ? 0 = 20.491(14) b lead to calculated cross sections whose values are in excess of their experimental counterparts.

  18. Neutron Scattering Cross Sections for Natural Carbon in the Energy Range 2-133 keV

    Microsoft Academic Search

    O Gritzay; M Gnidak; V Kolotyi; O Korol; V Razbudey; V Venedyktov; J H Richardson; K Sale

    2006-01-01

    Natural carbon is well known as reactor structure material and at the same time as one of the most important neutron scattering standards, especially at energies less than 2 MeV, where the neutron total and neutron scattering cross sections are essentially identical. The best neutron total cross section experimental data for natural carbon in the range 1-500 keV have uncertainties

  19. Impact-parameter dependence of energy loss for 625keV H[sup +] ions in Si single crystals

    Microsoft Academic Search

    A. Dygo; M. A. Boshart; L. E. Seiberling; N. M. Kabachnik

    1994-01-01

    The energy distributions for 625-keV H[sup +] ions transmitted through thin Si single crystals are studied for detailed angular scans through the [l angle]110[r angle] and [l angle]100[r angle] axial as well as the [l brace]111[r brace] and [l brace]110[r brace] planar channels. Well-resolved structures in the distributions taken near the [l angle]110[r angle] axial direction are observed. The experimental

  20. High energy resolution measurement of the /sup 238/U neutron capture yield in the energy region between 1 and 100 keV

    SciTech Connect

    Machlin, R.L.; Perez, R.B.; de Saussure, G.; Ingle, R.W.

    1988-01-01

    A measurement of the /sup 238/U neutron capture yield was performed at the 150 meter flight-path of the ORELA facility on two /sup 238/U samples (0.01224 and 0.0031 atomsbarn). The capture yeild data were normalized by Moxon's small resonance method. The energy resolution achieved in this measurement frequently resulted in doublet and triplet splittings of what appeared to be single resonance in previous measurements. This resolution should allow extension of the resolved resonance energy region in /sup 238/U from the present 4-keV limit up to 15 or 20 keV incident neutron energy. Some 200 small resonances of the (/sup 238/U /plus/ n) compound nucleus have been observed which had not been detected in transmission measurement, in the energy range from 250 eV to 10 keV.

  1. 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.

  2. Low-Energy (<10 keV) Electron Ionization and Recombination Model for a Liquid Argon Detector

    E-print Network

    Foxe, Michael; Jovanovic, Igor; Bernstein, Adam; Kazkaz, Kareem; Mozin, Vladimir; Pereverzev, Sergey; Sangiorgio, Samuele; Sorensen, Peter

    2014-01-01

    Detailed understanding of the ionization process in noble liquid detectors is important for their use in applications such as the search for dark matter and coherent elastic neutrino-nucleus scattering. The response of noble liquid detectors to low-energy ionization events is poorly understood at this time. We describe a new simulation tool which predicts the ionization yield from electronic energy deposits (E < 10keV) in liquid Ar, including the dependence of the yield on the applied electric drift field. The ionization signal produced in a liquid argon detector from $^{37}$Ar beta decay and $^{55}$Fe X-rays has been calculated using the new model.

  3. Multilayer x-ray optics for energies E > 8 keV and their application in x-ray analysis

    Microsoft Academic Search

    Reiner Dietsch; Stefan Braun; Thomas Holz; Hermann Mai; Roland Scholz; Lutz Bruegemann

    2000-01-01

    Performance of Ni\\/C, Ni\\/B4C, Mo\\/B4C and W\\/B4C multilayers in the energy range E > 8 keV is considered by simulation of x-ray reflectivity and resolution of 1st order Bragg reflection at three different photon energies. The results indicate, that Ni\\/C and Ni\\/B4C multilayers show highest theoretical reflectivities of R > 80% for Cu K(alpha) - radiation and also above the

  4. Electron energy spectra of H(-) autodetaching states resulting from collisions of H(-) with He at 1 KeV

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Sato, H.; Hino, K.; Matsuzawa, M.

    Electron energy spectra for H(-) autodetaching states resulting from collisions H(-) with He at 1 keV are rigorously calculated by including couplings between doubly excited states and continuum states and their interference with direct detachment processes. An energy sampling procedure, based on the Gauss quadratures, is used to discretize continuum states. The present theoretical result, for the first time, clarifies mechanisms of excitation to doubly excited states, quantitatively reproduces the experimental spectra first observed by Risley and Geballe in 1974, separates the contributions from each of three autodetaching states, and identifies the cause of the interference between autodetaching and direct-detaching excitation channels.

  5. Low-energy (< 10 keV) electron ionization and recombination model for a liquid argon detector

    NASA Astrophysics Data System (ADS)

    Foxe, M.; Hagmann, C.; Jovanovic, I.; Bernstein, A.; Kazkaz, K.; Mozin, V.; Pereverzev, S. V.; Sangiorgio, S.; Sorensen, P.

    2015-01-01

    Detailed understanding of the ionization process in noble liquid detectors is important for their use in applications such as the search for dark matter and coherent elastic neutrino-nucleus scattering. The response of noble liquid detectors to low-energy ionization events is poorly understood at this time. We describe a new simulation tool which predicts the ionization yield from electronic energy deposits (E < 10 keV) in liquid Ar, including the dependence of the yield on the applied electric drift field. The ionization signal produced in a liquid argon detector from 37Ar beta decay and 55Fe X-rays has been calculated using the new model.

  6. Resonance parameters of the reaction 12C(d,p?)13C in the vicinity of 1450 keV for accelerator energy calibration

    NASA Astrophysics Data System (ADS)

    Csedreki, L.; Szíki, G. Á.; Szikszai, Z.; Kocsis, I.

    2015-01-01

    The observed resonance parameters of the 12C(d,p?)13C reaction in the vicinity of 1450 keV deuteron energy have been determined in a thorough procedure, fitting our recent experimental excitation curve, as well as earlier literature data with the Root Software Package. The resulting energy and width (FWHM) of resonance are 1445.8 ± 0.2 keV and 5.3 ± 0.4 keV, respectively. We propose the application of this resonance as a precise and simple method for accelerator energy calibration when performing DIGE analysis.

  7. DWBA analysis of {sup 12}C(d,p){sup 13}C cross section data below 300 keV deuteron energy

    SciTech Connect

    Naqvi, A.A. [King Fahd Univ. of Petroleum and Minerals, Dhahran, (Saudi Arabia); Ayer, Z.; Ludwig, E. [King Fahd Univ. of Petroleum and Minerals, Dhahran (Saudi Arabia); [Duke Univ., Durham, NC (United States); [Univ. of North Carolina, Chappel Hill, NC (United States)

    1994-12-31

    {sup 12}C(d,p){sup 13}T differential cross section data at 200, 220, 250, 280 and 300 keV deuteron energies has been analyzed using finite range DWBA codes PTOLEMY and TWOFNR. It was observed that shape and magnitude of the cross section data at 300, 280 keV energies can be fitted well but the shape of 250, 220 and 200 keV data cannot be fitted. However 250, 220 and 200 keV data shape can be fitted by changing the optical model parameters at each energy. This indicates a very strong energy dependence of the optical model parameters data of the entrance channel over such a small energy range which is not observed in the presently available elastic scattering data of the entrance channel.

  8. Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV

    Microsoft Academic Search

    S. R. Manohara; S. M. Hanagodimath

    2007-01-01

    Effective atomic numbers for photon energy-absorption (ZPEAeff) of essential amino acids histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been calculated by a direct method in the energy region of 1 keV to 20 MeV. The ZPEAeff values have been found to change with energy and composition of the amino acids. The variations of mass energy-absorption coefficient, effective

  9. Effective atomic numbers for photon energy absorption of essential amino acids in the energy range 1 keV to 20 MeV

    Microsoft Academic Search

    S. R. Manohara; S. M. Hanagodimath

    2007-01-01

    Effective atomic numbers for photon energy-absorption (ZPEAeff) of essential amino acids histidine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine have been calculated by a direct method in the energy region of 1keV to 20MeV. The ZPEAeff values have been found to change with energy and composition of the amino acids. The variations of mass energy-absorption coefficient, effective atomic number

  10. Ionic fragmentation of CO and H2O under impact of 10 keV electrons: kinetic energy release distributions

    NASA Astrophysics Data System (ADS)

    Singh, Raj; Bhatt, Pragya; Yadav, Namita; Shanker, R.

    2014-04-01

    Dissociative ionization of COq+ (q=2-4) and H2Oq+ (q=2-3) molecular ions produced from the collisions of CO and H2O with 10 keV electrons is studied using time-of-flight mass spectrometer and position sensitive detector with multi-hit ability, respectively. The kinetic energy release distributions for these channels are obtained. We found that a pure Coulomb explosion model is insufficient to explain the observed kinetic release distributions for the Coulomb explosion channels. A detail of this study is given in references [3, 4].

  11. Absolute Calibration of Image Plate for electrons at energy between 100 keV and 4 MeV

    SciTech Connect

    Chen, H; Back, N L; Eder, D C; Ping, Y; Song, P M; Throop, A

    2007-12-10

    The authors measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV to 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on the solid density targets. This paper presents the calibration results of image plate Photon Stimulated Luminescence PSL per electrons at this energy range. The Monte Carlo radiation transport code MCNPX results are also presented for three representative incident angles onto the image plates and corresponding electron energies depositions at these angles. These provide a complete set of tools that allows extraction of the absolute calibration to other spectrometer setting at this electron energy range.

  12. Electron capture in H{sup +} + O{sub 2} collisions at low keV energies

    SciTech Connect

    Quintana, E.J.; Heckman, V.R.; Pollack, E.

    1993-05-01

    Electron capture in H{sup +}{sub +}O{sub 2} is studied at low keV energies and scattering angles 0<{theta}<1 deg. Time-of-flight techniques are used to identify the states excited. Using the H{sup +}{sub +}H{sub 2} collisions as an energy reference our results to date show that at an energy E=1.0 keV the ground state, H(1s)+O{sub 2}{sup +}(X), channel is dominant only for {theta}<0.3 deg. At a scattering angle of 1.0 deg the probability for capture into the ground state is 0.3. This channel is exothermic by Q=-1.5 eV and is excited via a vertical transit on second important process resulting in H(1s)+O{sub 2}{sup +} also found at small scattering angles. Other-channels are seen at larger angles in the range investigated. Additional results will be presented and interpreted.

  13. Simulations of Microchannel Plate Sensitivity to <20 keV X-rays as a Function of Energy and Incident Angle

    SciTech Connect

    Kruschwitz, Craig [NSTec; Wu, M. [SNL; Rochau, G. A. [SNL

    2013-06-13

    We present results of Monte Carlo simulations of microchannel plate (MCP) response to x-rays in the 250 eV to 20 keV energy range as a function of both x-ray energy and impact angle. The model is based on the model presented in Rochau et al. (2006). However, while the Rochau et al. (2006) model was two-dimensional, and their results only went to 5 keV, our results have been expanded to 20 keV, and our model has been incorporated into a three-dimensional Monte Carlo MCP model that we have developed over the past several years (Kruschwitz et al. 2011). X-ray penetration through multiple MCP pore walls is increasingly important above 5 keV. The effect of x-ray penetration through multiple pores on MCP performance was studied and is presented.

  14. Possible Contrast Media Reduction with Low keV Monoenergetic Images in the Detection of Focal Liver Lesions: A Dual-Energy CT Animal Study

    PubMed Central

    Chung, Yong Eun; You, Je Sung; Lee, Hye-Jeong; Lim, Joon Seok; Lee, Hye Sun; Baek, Song-Ee; Kim, Myeong-Jin

    2015-01-01

    Objective To investigate the feasibility of dual-energy CT for contrast media (CM) reduction in the diagnosis of hypervascular and hypovascular focal liver lesions (FLL). Subjects and Methods The Institutional Animal Care and Use Committee approved this study. VX2 tumors were implanted in two different segments of the liver in 13 rabbits. After 2 weeks, two phase contrast enhanced CT scans including the arterial phase (AP) and portal-venous phase (PVP) were performed three times with 24-hour intervals with three different concentrations of iodine, 300 (I300), 150 (I150) and 75 mg I/mL (I75). The mean HU and standard deviation (SD) were measured in the liver, the hypervascular portion of the VX2 tumor which represented hypervascular tumors, and the central necrotic area of the VX2 tumor which represented hypovascular tumors in 140kVp images with I300 as a reference standard and in monoenergetic images (between 40keV and 140keV) with I150 and I75. The contrast-to-noise ratio (CNR) for FLLs and the ratio of the CNRs (CNRratio) between monoenergetic image sets with I150 and I75, and the reference standard were calculated. Results For hypervascular lesions, the CNRratio was not statistically different from 1.0 between 40keV and 70keV images with I150, whereas the CNRratio was significantly lower than 1.0 in all keV images with I75. For hypovascular lesions, the CNRratio was similar to or higher than 1.0 between 40keV and 80keV with I150 and between 40keV and 70keV with I75. Conclusions With dual-energy CT, the total amount of CM might be halved in the diagnosis of hypervascular FLLs and reduced to one-fourth in the diagnosis of hypovascular FLLs, while still preserving CNRs. PMID:26203652

  15. First mu+SR studies on thin films with a new beam of low energy positive muons at energies below 20 keV

    Microsoft Academic Search

    T. Prokscha; M. Birke; E. Forgan; H. Glückler; A. Hofer; T. Jackson; K. Küpfer; J. Litterst; E. Morenzoni; Ch. Niedermayer; M. Pleines; T. Riseman; A. Schatz; G. Schatz; H. P. Weber; C. Binns

    1999-01-01

    At the Paul Scherrer Institute slow positive muons (mu+) with nearly 100% polarization and an energy of about 10 eV are generated by moderation of an intense secondary beam of surface muons in an appropriate condensed gas layer. These epithermal muons are used as a source of a tertiary beam of tunable energy between 10 eV and 20 keV. The

  16. First ? + SR studies on thin films with a new beam of low energy positive muons at energies below 20 keV

    Microsoft Academic Search

    T. Prokscha; M. Birke; E. Forgan; H. Glückler; A. Hofer; T. Jackson; K. Küpfer; J. Litterst; E. Morenzoni; Ch. Niedermayer; M. Pleines; T. Riseman; A. Schatz; G. Schatz; H. P. Weber; C. Binns

    1999-01-01

    At the Paul Scherrer Institute slow positive muons (?+) with nearly 100% polarization and an energy of about 10 eV are generated by moderation of an intense secondary beam of surface\\u000a muons in an appropriate condensed gas layer. These epithermal muons are used as a source of a tertiary beam of tunable energy\\u000a between 10 eV and 20 keV. The

  17. Total bremsstrahlung spectral photon distributions in metallic targets in the photon energy range of 5–10 keV by 204Tl beta particles

    Microsoft Academic Search

    Tajinder Singh; K. S. Kahlon; A. S. Dhaliwal

    2009-01-01

    Total bremsstrahlung spectral photon distributions produced by beta particles of the 204Tl beta emitter in thick targets of Al, Ti, Sn and Pb targets were evaluated at photon energies from 5keV to 10keV. Experimental measurements were compared with the theoretical total bremsstrahlung spectral photon distributions obtained from Elwert corrected (non-relativistic) Bethe–Heitler theory and modified Elwert factor (relativistic) Bethe–Heitler theories for

  18. Thick target bremsstrahlung spectra produced by 204Tl beta particles in the photon energy region of 10 30 keV

    Microsoft Academic Search

    Tajinder Singh; K. S. Kahlon; A. S. Dhaliwal

    2008-01-01

    Total bremsstrahlung (BS) spectra in thick targets of Al, Ti, Sn and Pb targets produced by complete absorption of 204Tl beta particles are studied at photon energy from 10 keV to 30 keV. The experimental BS spectra measured with X-PIPS Si(Li) detector are compared with the theoretical BS spectra obtained from Elwert corrected (non-relativistic) Bethe-Heitler theory and modified Elwert factor

  19. Total bremsstrahlung spectral photon distributions in metallic targets in the photon energy range of 5-10 keV by 204Tl beta particles

    Microsoft Academic Search

    Tajinder Singh; K. S. Kahlon; A. S. Dhaliwal

    2009-01-01

    Total bremsstrahlung spectral photon distributions produced by beta particles of the 204Tl beta emitter in thick targets of Al, Ti, Sn and Pb targets were evaluated at photon energies from 5 keV to 10 keV. Experimental measurements were compared with the theoretical total bremsstrahlung spectral photon distributions obtained from Elwert corrected (non-relativistic) Bethe-Heitler theory and modified Elwert factor (relativistic) Bethe-Heitler

  20. 12.6 keV Kr K-alpha X-ray Source For High Energy Density Physics Experiments

    SciTech Connect

    Kugland, N; Constantin, C G; Niemann, C; Neumayer, P; Chung, H; Doppner, T; Kemp, A; Glenzer, S H; Girard, F

    2008-04-22

    A high contrast 12.6 keV Kr K{alpha} source has been demonstrated on the petawatt-class Titan laser facility. The contrast ratio (K{alpha} to continuum) is 65, with a competitive ultra short pulse laser to x-ray conversion efficiency of 10{sup -5}. Filtered shadowgraphy indicates that the Kr K{alpha} and K{beta} x-rays are emitted from a roughly 1 x 2 mm emission volume, making this source suitable for area backlighting and scattering. Spectral calculations indicate a typical bulk electron temperature of 50-70 eV (i.e. mean ionization state 13-16), based on the observed ratio of K{alpha} to K{beta}. Kr gas jets provide a debris-free high energy K{alpha} source for time-resolved diagnosis of dense matter.

  1. Dosimetric prerequisites for routine clinical use of photon emitting brachytherapy sources with average energy higher than 50 kev

    SciTech Connect

    Li Zuofeng; Das, Rupak K.; De Werd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Perez-Calatayud, Jose; Rivard, Mark J.; Sloboda, Ronald S.; Williamson, Jeffrey F. [Department of Radiation Oncology, University of Florida, Gainesville, Florida 32610 (United States); Department of Human Oncology, University of Wisconsin, Madison, Wisconsin 53792 (United States); Accredited Dosimetry Calibration Laboratory, University of Wisconsin, Madison, Wisconsin 53706 (United States); Radiological Physics Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Medicine, University of Kentucky, Lexington, Kentucky 40536 (United States); Radiotherapy Department, Hospital La Fe, Valencia 46009 (Spain); Department of Radiation Oncology, Tufts-New England Medical Center, Boston, Massachusetts 02111 (United States); Cross Cancer Institute, Edmonton, AB T6G 1Z2 (Canada); Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)

    2007-01-15

    This paper presents the recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Therapeutic Radiology and Oncology (ESTRO) on the dosimetric parameters to be characterized, and dosimetric studies to be performed to obtain them, for brachytherapy sources with average energy higher than 50 keV that are intended for routine clinical use. In addition, this document makes recommendations on procedures to be used to maintain vendor source strength calibration accuracy. These recommendations reflect the guidance of the AAPM and the ESTRO for its members, and may also be used as guidance to vendors and regulatory agencies in developing good manufacturing practices for sources used in routine clinical treatments.

  2. Study of the surface activation of ETFE by low energy (keV) Si and N bombardment

    NASA Astrophysics Data System (ADS)

    Parada, M. A.; de Almeida, A.; Muntele, C.; Muntele, I.; Delalez, N.; Ila, D.

    2005-12-01

    The ethylenetetrafluoroethylene (ETFE) is a polymer formed by alternating ethylene and tetrafluoroethylene segments. It can be applied in the field of medical physics as intra venous catheters and as radiation dosimeters. The increasing application of polymeric materials in technological and scientific fields has motivated the use of surface treatments to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionizing radiation, it suffers damage leading to surface activation depending on the type, energy and intensity of the applied radiation. In order to determine the radiation damage and the surface activation mechanism ETFE films were bombarded with keV Si and N at various fluences. The bombarded film was also analyzed with optical absorption photospectrometry (OAP), Raman and Fourier transform infrared-attenuated total reflectance (FTIR-ATR) spectroscopy showing quantitatively the chemical nature at the damage caused by the Si and N bombardment.

  3. Fine pitch CdTe-based Hard-X-ray polarimeter performance for space science in the 70-300 keV energy range

    E-print Network

    S. Antier; O. Limousin; P. Ferrando

    2015-05-05

    X-rays astrophysical sources have been almost exclusively characterized through imaging, spectroscopy and timing analysis. Nevertheless, more observational parameters are needed because some radiation mechanisms present in neutrons stars or black holes are still unclear. Polarization measurements will play a key role in discrimination between different X-ray emission models. Such a capability becomes a mandatory requirement for the next generation of high-energy space proposals. We have developed a CdTe-based fine-pitch imaging spectrometer, Caliste, able to respond to these new requirements. With a 580-micron pitch and 1 keV energy resolution at 60 keV, we are able to accurately reconstruct the polarization angle and polarization fraction of an impinging flux of photons which are scattered by 90{\\deg} after Compton diffusion within the crystal. Thanks to its high performance in both imaging and spectrometry, Caliste turns out to be a powerful device for high-energy polarimetry. In this paper, we present the principles and the results obtained for this kind of measurements: on one hand, we describe the simulation tool we have developed to predict the polarization performances in the 50-300 keV energy range. On the other hand, we compare simulation results with experimental data taken at ESRF ID15A (European Synchrotron Radiation Facility) using a mono-energetic polarized beam tuned between 35 and 300 keV. We show that it is possible with this detector to determine with high precision the polarization parameters (direction and fraction) for different irradiation conditions. Applying a judicious energy selection to our data set, we reach a remarkable sensitivity level characterized by an optimum Quality Factor of 0.78 in the 200-300 keV range. We also evaluate the sensitivity of our device at 70 keV, where hard X-ray mirrors are already available; the measured Q factor is 0.64 at 70 keV.

  4. Ionic fragmentation of the CO molecule by impact of 10-keV electrons: Kinetic-energy-release distributions

    NASA Astrophysics Data System (ADS)

    Singh, Raj; Bhatt, Pragya; Yadav, Namita; Shanker, R.

    2013-02-01

    The ionic fragmentation of a multiply charged CO molecule is studied under impact of 10-keV electrons using recoil-ion momentum spectroscopy. The kinetic-energy-release distributions for the various fragmentation channels arising from the dissociation of COq+ (q = 2-4) are measured and discussed in light of theoretical calculations available in the literature. It is observed that the present kinetic-energy-release values are much smaller than those predicted by the Coulomb explosion model. The kinetic-energy-release distribution for the C++O+ channel is suggested to arise from the tunneling process. It is seen that the peak of kinetic-energy-release distribution is larger for that dissociation channel that arises from the same molecular ion which has higher charge on the oxygen atom. Further, the relative ionic fractions for seven ion species originating from ionization and subsequent dissociation of the CO molecule are obtained and compared with the existing data reported at low energy of the electron impact. The precursor-specific relative partial ionization cross sections are also obtained and shown to be about 66.4% from single ionization, 29.9% from double ionization, 3.3% from triple ionization, and about 0.4% from quadruple ionization of the precursor CO molecule contributing to the total fragment ion yield.

  5. Dosimetric properties of high energy current (HEC) detector in keV x-ray beams

    NASA Astrophysics Data System (ADS)

    Zygmanski, Piotr; Shrestha, Suman; Elshahat, Bassem; Karellas, Andrew; Sajo, Erno

    2015-04-01

    We introduce a new x-ray radiation detector. The detector employs high-energy current (HEC) formed by secondary electrons consisting predominantly of photoelectrons and Auger electrons, to directly convert x-ray energy to detector signal without externally applied power and without amplification. The HEC detector is a multilayer structure composed of thin conducting layers separated by dielectric layers with an overall thickness of less than a millimeter. It can be cut to any size and shape, formed into curvilinear surfaces, and thus can be designed for a variety of QA applications. We present basic dosimetric properties of the detector as function of x-ray energy, depth in the medium, area and aspect ratio of the detector, as well as other parameters. The prototype detectors show similar dosimetric properties to those of a thimble ionization chamber, which operates at high voltage. The initial results obtained for kilovoltage x-rays merit further research and development towards specific medical applications.

  6. First direct high-precision energy determination for the 8.4 and 20.7 keV nuclear transitions in 169Tm

    NASA Astrophysics Data System (ADS)

    Inoyatov, A. Kh.; Kovalík, A.; Filosofov, D. V.; Ryšavý, M.; Perevoshchikov, L. L.; Gurov, Yu. B.

    2015-06-01

    Energies of 8410.1 ± 0.4, 20743.9 ± 0.3, and 63121.6 ± 1.2 eV were determined for the 8.4 keV M1 + E2, 20.7 keV M1 + E2, and 63.1 keV E1 nuclear transitions in 169Tm (generated in the EC decay of 169Yb, respectively, by means of the internal conversion electron spectroscopy. The 169Yb sources used were prepared by vacuum evaporation deposition on polycrystalline carbon and platinum foils as well as by ion implantation at 30keV into a polycrystalline aluminum foil. The relevant conversion electron spectra were measured by a high-resolution combined electrostatic electron spectrometer at 7 eV instrumental resoluition. Values of 0.0326(14) and 0.0259(17) were derived from our experimental data for the E2 admixture parameter |? ( E2/ M1)| for the 8.4 and 20.7 keV transitions, respectively. A possible effect of nuclear structure on multipolarity of the 20.7 keV transition was also investigated.

  7. Dosimetric properties of high energy current (HEC) detector in keV x-ray beams.

    PubMed

    Zygmanski, Piotr; Shrestha, Suman; Elshahat, Bassem; Karellas, Andrew; Sajo, Erno

    2015-04-01

    We introduce a new x-ray radiation detector. The detector employs high-energy current (HEC) formed by secondary electrons consisting predominantly of photoelectrons and Auger electrons, to directly convert x-ray energy to detector signal without externally applied power and without amplification. The HEC detector is a multilayer structure composed of thin conducting layers separated by dielectric layers with an overall thickness of less than a millimeter. It can be cut to any size and shape, formed into curvilinear surfaces, and thus can be designed for a variety of QA applications. We present basic dosimetric properties of the detector as function of x-ray energy, depth in the medium, area and aspect ratio of the detector, as well as other parameters. The prototype detectors show similar dosimetric properties to those of a thimble ionization chamber, which operates at high voltage. The initial results obtained for kilovoltage x-rays merit further research and development towards specific medical applications. PMID:25789488

  8. Laboratory-based X-ray reflectometer for multilayer characterization in the 15-150 keV energy band.

    PubMed

    Windt, David L

    2015-04-01

    A laboratory-based X-ray reflectometer has been developed to measure the performance of hard X-ray multilayer coatings at their operational X-ray energies and incidence angles. The instrument uses a sealed-tube X-ray source with a tungsten anode that can operate up to 160 kV to provide usable radiation in the 15-150 keV energy band. Two sets of adjustable tungsten carbide slit assemblies, spaced 4.1 m apart, are used to produce a low-divergence white beam, typically set to 40 ?m × 800 ?m in size at the sample. Multilayer coatings under test are held flat using a vacuum chuck and are mounted at the center of a high-resolution goniometer used for precise angular positioning of the sample and detector; additionally, motorized linear stages provide both vertical and horizontal adjustments of the sample position relative to the incident beam. A CdTe energy-sensitive detector, located behind a third adjustable slit, is used in conjunction with pulse-shaping electronics and a multi-channel analyzer to capture both the incident and reflected spectra; the absolute reflectance of the coating under test is computed as the ratio of the two spectra. The instrument's design, construction, and operation are described in detail, and example results are presented obtained with both periodic, narrow-band and depth-graded, wide-band hard X-ray multilayer coatings. PMID:25933841

  9. Studies of internal bremsstrahlung spectrum of (35)S beta emitter in the photon energy region of 1-100 keV.

    PubMed

    Singh, Amrit; Dhaliwal, A S

    2014-12-01

    The internal bremsstrahlung (IB) spectral photon distribution, produced by soft beta particles of (35)S (Wmax=164keV), in the photon energy region of 1-100keV, is measured by using a Si(Li) detector, having high energy resolution and efficiency at low energy region. The measured spectral IB photon distribution is compared with KUB theory and Coulomb corrected IB theories given by Nilsson, and Lewis and Ford. After applying the necessary corrections, the experimental and theoretical IB spectral photon distributions are compared in terms of the number of IB photon of energy k per moc(2) per unit photon yield. In the low energy region (below 10keV), the experimental results are in agreement with all the theories. However, in photon energy region of 10-50keV, experimental results are in agreement with Coulomb corrected Nilsson theory only, within the experimental errors. Further, beyond 50keV, the Nilsson theory is more close to the experimental results than the KUB, and the Lewis and Ford theories. Hence, the Nilsson theory is more accurate than the other theories given by KUB and Lewis and Ford, particularly at a high energy end. The experimental results reported here with Si(Li) detector are free from number of ambiguities in earlier measurements reported with NaI(Tl) and HPGe detectors. The present results are indicating a relook into the theoretical considerations, given by different theories, while taking into account the Coulomb corrections for predicting the IB spectrum, particularly at high photon energy region. PMID:25103247

  10. A balloon-borne instrument for high-resolution astrophysical spectroscopy in the 20-8000 keV energy range

    NASA Technical Reports Server (NTRS)

    Paciesas, W. S.; Baker, R.; Boclet, D.; Brown, S.; Cline, T.; Costlow, H.; Durouchoux, P.; Ehrmann, C.; Gehrels, N.; Hameury, J. M.

    1983-01-01

    The Low Energy Gamma ray Spectrometer (LEGS) is designed to perform fine energy resolution measurements of astrophysical sources. The instrument is configured for a particular balloon flight with either of two sets of high purity germanium detectors. In one configuration, the instrument uses an array of three coaxial detectors (effective volume equal to or approximately 230 cubic cm) inside an NaI (T1) shield and collimator (field of view equal to or approximately 16 deg FWHM) and operates in the 80 to 8000 keV energy range. In the other configuration, three planar detectors (effective area equal to or approximately square cm) surrounded by a combination of passive Fe and active NaI for shielding and collimation (field of view equal to or approximately 5 deg x 10 deg FWHM) are optimized for the 20 to 200 keV energy range. In a typical one day balloon flight, LEGS sensitivity limit (3 sigma) for narrow line features is less than or approximately .0008 ph/cm/s square (coaxial array: 80 to 2000 keV) and less than or approximately .0003 ph/square cm/s (planar array: 50 to 150 keV).

  11. Backscattering of He$sup +$ and H$sup +$ particles from ultra-thin films in the energy range 50--100 keV

    Microsoft Academic Search

    H. J. Goldberg; H. E. Jack; E. B. Dale

    1975-01-01

    Elastic collision cross sections of He$sup +$ and H$sup +$ ions incident ; on Au, Ag, Cu, Bi, Ni, and In, of density equivalent to less than a monolayer of ; target material, have been measured in the energy range 50--100 keV by the ; measurement of particles backscattered through a laboratory angle of 150degree. ; The results point to

  12. 236 U total neutron cross section in the energy range 1.8-734 keV

    Microsoft Academic Search

    O. A. Purtov; L. L. Litvinskii; A. V. Murzin; G. M. Novoselov

    1993-01-01

    The total neutron cross section for 236U is studied in a large number of experimental works: [2-4] - in the region of the resolved resonances by the time-of-flight method and [5] in the region of unresolved resonances (above 5 keV), where the total neutron cross section and the cross section for radiative capture of neutrons in the range 5-800 keV

  13. Non-proportional response between 0.1-100keV energy by means of highly monochromatic synchrotron X-rays

    E-print Network

    Ivan V. Khodyuk; Johan T. M. de Haas; Pieter Dorenbos

    2011-01-24

    Using highly monochromatic X-ray synchrotron irradiation ranging from 9 keV to 100 keV, accurate Lu2SiO5:Ce3+,Ca (LSO), Lu3Al5O12:Pr3+ (LuAG), Lu2Si2O7:Ce3+ (LPS) and Gd2SiO5:Ce3+ (GSO) non-proportional response curves were determined. By utilizing information from escape peaks in pulse height spectra the response curve can be extended down to several keV. A detailed study of the non-proportionality just above the K-edge is presented and from that a method, which we named K-dip spectroscopy, is obtained to reconstruct the electron response curve down to energies as low as 100 eV.

  14. Measurement of high-energy (10–60 keV) x-ray spectral line widths with eV accuracy

    SciTech Connect

    Seely, J. F., E-mail: seelyjf@gmail.com; Feldman, U. [Artep Inc., 2922 Excelsior Springs Court, Ellicott City, Maryland 21042 (United States); Glover, J. L.; Hudson, L. T.; Ralchenko, Y.; Henins, Albert [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Pereira, N. [Ecopulse Inc., P. O. Box 528, Springfield, Virginia 22152 (United States); Di Stefano, C. A.; Kuranz, C. C.; Drake, R. P. [University of Michigan, Ann Arbor, Michigan 48109 (United States); Chen, Hui; Williams, G. J.; Park, J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States)

    2014-11-15

    A high resolution crystal spectrometer utilizing a crystal in transmission geometry has been developed and experimentally optimized to measure the widths of emission lines in the 10–60 keV energy range with eV accuracy. The spectrometer achieves high spectral resolution by utilizing crystal planes with small lattice spacings (down to 2d = 0.099 nm), a large crystal bending radius and Rowland circle diameter (965 mm), and an image plate detector with high spatial resolution (60 ?m in the case of the Fuji TR image plate). High resolution W L-shell and K-shell laboratory test spectra in the 10–60 keV range and Ho K-shell spectra near 47 keV recorded at the LLNL Titan laser facility are presented. The Ho K-shell spectra are the highest resolution hard x-ray spectra recorded from a solid target irradiated by a high-intensity laser.

  15. Variation in the calibrated response of LiF, Al2O3, and silicon dosimeters when used for in-phantom measurements of source photons with energies between 30 KeV AND 300 KeV.

    PubMed

    Poudel, Sashi; Currier, Blake; Medich, David C

    2015-04-01

    The MCNP5 radiation transport code was used to quantify changes in the absorbed dose conversion factor for LiF, Al2O3, and silicon-based electronic dosimeters calibrated in-air using standard techniques and summarily used to measure absorbed dose to water when placed in a water phantom. A mono-energetic photon source was modeled at energies between 30 keV and 300 keV for a point-source placed at the center of a water phantom, a point-source placed at the surface of the phantom, and for a 10-cm radial field geometry. Dosimetric calculations were obtained for water, LiF, Al2O3, and silicon at depths of 0.2 cm and 10 cm from the source. These results were achieved using the MCNP5 *FMESH photon energy-fluence tally, which was coupled with the appropriate DE/DF card for each dosimetric material studied to convert energy-fluence into the absorbed dose. The dosimeter's absorbed dose conversion factor was calculated as a ratio of the absorbed dose to water to that of the dosimeter measured at a specified phantom depth. The dosimeter's calibration value also was obtained. Based on these results, the absorbed dose conversion factor for a LiF dosimeter was found to deviate from its calibration value by up to 9%, an Al2O3 dosimeter by 43%, and a silicon dosimeter by 61%. These data therefore can be used to obtain LiF, Al2O3, and silicon dosimeter correction factors for mono-energetic and poly-energetic sources at measurement depths up to 10 cm under the irradiation geometries investigated herein. PMID:25706137

  16. Measurement of the internal bremsstrahlung spectrum of a (89)Sr beta emitter in the 1-100keV photon energy regime.

    PubMed

    Singh, Amrit; Dhaliwal, A S

    2015-04-01

    The internal bremsstrahlung (IB) spectrum of (89)Sr, which is a unique first forbidden beta emitter, is studied in the 1-100keV photon energy regime. The IB spectrum is experimentally measured using a Si(Li) detector, which is efficient in this photon energy regime, and is compared with the IB distributions that are predicted by the Knipp, Uhlenbeck and Bloch (KUB), Nilsson, and Lewis and Ford theories. In the soft energy regime up to 15keV, the measured results are in agreement with all the aforementioned theories. However, from 16-30keV, the experimental results are in agreement with the Lewis and Ford theory, which applies to forbidden transitions, and at higher photon energies, the Nilsson theory best describes the measured results. The differences among the different theories also increase with the photon energy. The effect of the electrostatic Coulomb field on the IB process for beta emitters with different end-point energies is investigated by comparing the ratio of the IB probabilities predicted using the KUB and Nilsson theories for (35)S and (89)Sr, i.e., soft and hard beta emitters, respectively. The Coulomb effect is shown to be significant in the high photon energy regime and for beta emitters with low end-point energies. PMID:25675900

  17. The response of a fast phosphor screen scintillator (ZnO:Ga) to low energy ions (0-60 keV).

    PubMed

    Jiménez-Rey, D; Zurro, B; Rodríguez-Barquero, L; Baciero, A; Navarro, M

    2010-10-01

    ZnO:Ga is a promising, high time resolution candidate for use as a fast-ion-loss detector in TJ-II. We compare its ionoluminescence with that of the standard fast-ion-loss detector material, SrGa(2)S(4):Eu (also known as TG-Green), when irradiated by H(+) ions with a range of energies E?60?keV using a dedicated laboratory setup. It is found that ZnO:Ga is a reasonably good candidate for detecting low energy (E<60?keV) ions as it has excellent time resolution; however, its sensitivity is about 100 times lower than TG-Green, potentially limiting it to applications with high energy ion loss signals. PMID:21033843

  18. Measurements and assessment of 12C(d,p?)13C reaction cross sections in the deuteron energy range 740-2000 keV for analytical applications

    NASA Astrophysics Data System (ADS)

    Csedreki, L.; Uzonyi, I.; Szíki, G. Á.; Szikszai, Z.; Gyürky, Gy.; Kiss, Á. Z.

    2014-06-01

    The total cross sections of the 12C(d,p?1)13C (E? = 3089 keV), 12C(d,p?2)13C (E? = 3684 keV) and 12C(d,p?3)13C (E? = 3854 keV) reactions, as well as differential cross sections for (d,po), (d,p1) reactions and (d,d0) elastic scattering were determined in the 740-2000 keV deuteron energy range using a self-supporting natural carbon foil and detecting the gamma-rays and particles simultaneously. In order to test the validity of the measured gamma-ray producing cross sections, benchmark experiments were performed using kapton foils with two different thicknesses. Both the obtained gamma- and particle production cross section results were compared with data existing in literature, and in the case of (d,po) the experimental differential cross section data were compared also with the theoretical evaluated values.

  19. Effective atomic numbers of different types of materials for proton interaction in the energy region 1 keV-10 GeV

    NASA Astrophysics Data System (ADS)

    Kurudirek, Murat

    2014-10-01

    The effective atomic numbers (Zeff) of different types of materials such as tissues, tissue equivalents, organic compounds, glasses and dosimetric materials have been calculated for total proton interactions in the energy region 1 keV-10 GeV. Also, effective atomic numbers relative to water (ZeffRW) have been presented in the entire energy region for the materials that show better water equivalent properties. Some human tissues such as adipose tissue, bone compact, muscle skeletal and muscle striated have been investigated in terms of tissue equivalency by comparing Zeff values and the better tissue equivalents have been determined for these tissues. With respect to the variation of Zeff with kinetic energy, it has been observed that Zeff seems to be more or less the same in the energy region 400 keV-10 GeV for the given materials except for the photographic emulsion, calcium fluoride, silicon dioxide, aluminum oxide and Teflon. The values of Zeff have found to be constant for photographic emulsion after 1 GeV, for calcium fluoride between 1 MeV and 1 GeV and for silicon dioxide, aluminum oxide and Teflon between 400 keV and 1 GeV. This constancy clearly shows the availability of using Zeff in estimating radiation response of the materials at first glance.

  20. Two-photon above-threshold ionization of hydrogen over the photon energy range from 15 eV to 50 keV

    SciTech Connect

    Florescu, Viorica; Budriga, Olimpia; Bachau, Henri [Department of Physics and Centre for Advanced Quantum Physics, University of Bucharest, MG-11, R-077125 Bucharest-Magurele (Romania); National Institute for Laser, Plasma and Radiation Physics, R-077125 Bucharest-Magurele (Romania); Centre des Lasers Intenses et Applications, Universite Bordeaux I-CNRS-CEA, F-33405 Talence Cedex (France)

    2011-09-15

    We investigate the absorption of two identical photons from the ground state of hydrogen-like atoms over an energy range that extends beyond that explored up to now. Our approach is based on a hybrid formula, valid in second-order perturbation theory, in which the A{sup 2} contribution from the nonrelativistic Hamiltonian is treated exactly, while the A{center_dot}P contribution is calculated in dipole approximation. We find that, at least up to 50 keV, the nonrelativistic dipole approximation, based only on the A{center_dot}P contribution, determines the values of the total cross section. Our numerical results, covering photon energies from 90 nm (13.7 eV) to 0.0248 nm (50 keV) are in very good agreement with most previous theoretical works. Differences with recent results are discussed.

  1. Dose distribution of a 125 keV mean energy microplanar x-ray beam for basic studies on microbeam radiotherapy

    SciTech Connect

    Ohno, Yumiko; Torikoshi, Masami; Suzuki, Masao; Umetani, Keiji; Imai, Yasuhiko; Uesugi, Kentaro; Yagi, Naoto [National Institute of Radiological Sciences, 4-9-1 Anagawa, Inage, Chiba 263-8555 (Japan); Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2008-07-15

    A multislit collimator was designed and fabricated for basic studies on microbeam radiation therapy (MRT) with an x-ray energy of about 100 keV. It consists of 30 slits that are 25 {mu}m high, 30 mm wide, and 5 mm thick in the beam direction. The slits were made of 25 {mu}m-thick polyimide sheets that were separated by 175 {mu}m-thick tungsten sheets. The authors measured the dose distribution of a single microbeam with a mean energy of 125 keV by a scanning slit method using a phosphor coupled to a charge coupled device camera and found that the ratios of the dose at the center of a microbeam to that at midpositions to adjacent slits were 1050 and 760 for each side of the microbeam. This dose distribution was well reproduced by the Monte Carlo simulation code PHITS.

  2. X-ray attenuation cross sections for energies 100 eV to 100 keV and elements Z = 1 to Z = 92

    Microsoft Academic Search

    E. B. Saloman; J. H. Hubbell; J. H. Scofield

    1988-01-01

    This work presents for the energy range 0.1--100 keV the National Bureau of Standards (NBS) database of experimental x-ray attenuation coefficients (total absorption cross sections) and cross sections calculated using a relativistic Hartree--Slater model for the photoelectric cross section for all elements of atomic number Z = 1--92. The information is displayed in both tabular and graphical form. Also shown

  3. Energy spectra from coupled electron-photon slowing down. [10 keV to 10 GeV, EGATL in FORTRAN IV

    Microsoft Academic Search

    Beck

    1976-01-01

    A coupled electron-photon slowing down calculation for determining electron and photon track length in uniform homogeneous media is described. The method also provides fluxes for uniformly distributed isotropic sources. Source energies ranging from 10 keV to over 10 GeV are allowed and all major interactions are treated. The calculational technique and related cross sections are described in detail and sample

  4. Photoelectric cross sections of gamma rays in Al, Cu, Sn, W, Au and Pb in the energy region 50-208 keV

    Microsoft Academic Search

    K. Parthasaradhi

    1968-01-01

    Total photoelectric cross sections of gamma rays are determined by subtracting the theoretical scattering cross sections from the experimental total gamma-ray cross sections of Wiedenbeck in the elements Al, Cu, Sn, W, Au and Pb in the energy region 50-208 keV. These values are compared with the latest theoretical values of Rakavy and Ron, Schmickley and Pratt and the compiled

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

  6. Absolute differential cross sections for small-angle H sup + -He direct and charge-transfer scattering at keV energies

    SciTech Connect

    Johnson, L.K.; Gao, R.S.; Dixson, R.G.; Smith, K.A.; Lane, N.F.; Stebbings, R.F. (Department of Physics, Department of Space Physics and Astronomy, and Rice Quantum Institute, Rice University, P.O. Box 1892, Houston, Texas 77251 (US)); Kimura, M. (Department of Physics, Rice University, Houston, Texas 77251 Argonne National Laboratory, ER 203, 9700 Cass Avenue, Argonne, Illinois 60439)

    1989-10-01

    This paper reports measurements and calculations of absolute differential cross sections for H{sup +}-He charge-transfer and direct scattering. Charge-transfer measurements have been obtained at 5.0 keV laboratory energy over the laboratory angular range 0.02{degree}--1.0{degree}, while direct scattering has been observed at 0.5, 1.5, and 5.0 keV laboratory energy over a closely corresponding angular range. Calculations are reported for 0.5, 1.5, and 5.0 keV charge-transfer and direct scattering. The measured cross sections are in good agreement with those derived from fully quantum-mechanical molecular-orbital close-coupling calculations. Direct scattering cross sections are also found to be in agreement with single-potential calculations using directly summed Jeffreys-Wentzel-Kramers-Brillouin phase shifts derived from proposed H{sup +}-He ground-state interaction potentials. The cross sections exhibit significant structure over the range of angles and energies studied. The measured cross sections have been integrated over the experimental angular range providing absolute integral cross sections for comparison with theoretical results and previously measured total cross sections.

  7. An innovative experimental setup for the measurement of sputtering yield induced by keV energy ions.

    PubMed

    Salou, P; Lebius, H; Benyagoub, A; Langlinay, T; Lelièvre, D; Ban-d'Etat, B

    2013-09-01

    An innovative experimental equipment allowing to study the sputtering induced by ion beam irradiation is presented. The sputtered particles are collected on a catcher which is analyzed in situ by Auger electron spectroscopy without breaking the ultra high vacuum (less than 10(-9) mbar), avoiding thus any problem linked to possible contamination. This method allows to measure the angular distribution of sputtering yield. It is now possible to study the sputtering of many elements such as carbon based materials. Preliminary results are presented in the case of highly oriented pyrolytic graphite and tungsten irradiated by an Ar(+) beam at 2.8 keV and 7 keV, respectively. PMID:24089874

  8. An innovative experimental setup for the measurement of sputtering yield induced by keV energy ions

    SciTech Connect

    Salou, P.; Lebius, H.; Benyagoub, A.; Langlinay, T.; Lelièvre, D.; Ban-d’Etat, B. [CIMAP (CEA-CNRS-ENSICAEN-UCBN), Boulevard Henri Becquerel, BP 5133, 14070 Caen Cedex 5 (France)] [CIMAP (CEA-CNRS-ENSICAEN-UCBN), Boulevard Henri Becquerel, BP 5133, 14070 Caen Cedex 5 (France)

    2013-09-15

    An innovative experimental equipment allowing to study the sputtering induced by ion beam irradiation is presented. The sputtered particles are collected on a catcher which is analyzed in situ by Auger electron spectroscopy without breaking the ultra high vacuum (less than 10{sup ?9} mbar), avoiding thus any problem linked to possible contamination. This method allows to measure the angular distribution of sputtering yield. It is now possible to study the sputtering of many elements such as carbon based materials. Preliminary results are presented in the case of highly oriented pyrolytic graphite and tungsten irradiated by an Ar{sup +} beam at 2.8 keV and 7 keV, respectively.

  9. Neutron Resonance Parameters of 238U and the Calculated Cross Sections from the Reich-Moore Analysis of Experimental Data in the Neutron Energy Range from 0 keV to 20 keV

    SciTech Connect

    Derrien, H

    2005-12-05

    The neutron resonance parameters of {sup 238}U were obtained from a SAMMY analysis of high-resolution neutron transmission measurements and high-resolution capture cross section measurements performed at the Oak Ridge Electron Linear Accelerator (ORELA) in the years 1970-1990, and from more recent transmission and capture cross section measurements performed at the Geel Linear Accelerator (GELINA). Compared with previous evaluations, the energy range for this resonance analysis was extended from 10 to 20 keV, taking advantage of the high resolution of the most recent ORELA transmission measurements. The experimental database and the method of analysis are described in this report. The neutron transmissions and the capture cross sections calculated with the resonance parameters are compared with the experimental data. A description is given of the statistical properties of the resonance parameters and of the recommended values of the average parameters. The new evaluation results in a slight decrease of the effective capture resonance integral and improves the prediction of integral thermal benchmarks by 70 pcm to 200 pcm.

  10. Electron energy spectra of H{sup {minus}} autodetaching states resulting from collisions of H{sup {minus}} with He at 1 keV

    SciTech Connect

    Kimura, M. [Argonne National Lab., IL (United States); Sato, H. [Argonne National Lab., IL (United States)]|[Rice Univ., Houston, TX (United States). Dept. of Physics; Hino, K.; Matsuzawa, M. [Univ. of Electro-Communications, Chofu, Tokyo (Japan). Dept. of Applied Physics and Chemistry

    1995-06-01

    Electron energy spectra for H{sup {minus}} autodetaching states resulting from collisions H{sup {minus}} with He at 1 keV are rigorously calculated by including couplings between doubly excited states and continuum states and their interference with direct detachment processes. An energy sampling procedure, based on the Gauss quadratures, is used to discretize continuum states. The present theoretical result, for the first time, clarifies mechanisms of excitation to doubly excited states, quantitatively reproduces the experimental spectra first observed by Risley and Geballe in 1974, separates the contributions from each of three autodetaching states, and identifies the cause of the interference between autodetaching and direct-detaching excitation channels.

  11. High-energy-resolution monochromator for nuclear resonant scattering of synchrotron radiation by Te-125 at 35.49 keV

    NASA Astrophysics Data System (ADS)

    Imai, Yasuhiko; Yoda, Yoshitaka; Kitao, Shinji; Masuda, Ryo; Higashitaniguchi, Satoshi; Inaba, Chika; Seto, Makoto

    2007-09-01

    We have developed a high-resolution monochromator (HRM) for the measurement of nuclear resonant scattering (NRS) of synchrotron radiation by Te-125 at 35.49 keV using the backscattering of sapphire (9 1 -10 68). HRMs for nuclei with excitation energies less than 30 keV have been successfully developed using high angle diffractions by silicon crystals. Nearly perfect silicon crystal, however, is not suitable for high efficient HRMs at higher energy regions because the symmetry of the crystal structure is high and the Debye-temperature is low. Therefore, we used high quality synthetic sapphire crystal, which has low symmetry of crystal structure and high Debye-temperature. The temperature of the crystal was precisely controlled around 218 K to diffract synchrotron radiation with a Bragg angle of ?/2 - 0.52 mrad. Energy was tuned by changing the crystal temperature under the condition of constant diffraction angle. Energy resolution was measured by detecting nuclear forward scattering by Te-125 in enriched TeO II. The relative energy resolution of 2.1×10 -7 is achieved, that is 7.5 meV in energy bandwidth. This HRM opens studies on element-specific dynamics and electronic state of substances containing Te-125.

  12. Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for High Energy Density plasmas at energies below 10 keV

    NASA Astrophysics Data System (ADS)

    Valdivia, M. P.; Stutman, D.; Finkenthal, M.

    2014-07-01

    The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities. We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 ?m size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

  13. Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for High Energy Density plasmas at energies below 10 keV

    SciTech Connect

    Valdivia, M. P.; Stutman, D.; Finkenthal, M. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

    2014-07-15

    The highly localized density gradients expected in High Energy Density (HED) plasma experiments can be characterized by x-ray phase-contrast imaging in addition to conventional attenuation radiography. Moiré deflectometry using the Talbot-Lau grating interferometer setup is an attractive HED diagnostic due to its high sensitivity to refraction induced phase shifts. We report on the adaptation of such a system for operation in the sub-10 keV range by using a combination of free standing and ultrathin Talbot gratings. This new x-ray energy explored matches well the current x-ray backlighters used for HED experiments, while also enhancing phase effects at lower electron densities. We studied the performance of the high magnification, low energy Talbot-Lau interferometer, for single image phase retrieval using Moiré fringe deflectometry. Our laboratory and simulation studies indicate that such a device is able to retrieve object electron densities from phase shift measurements. Using laboratory x-ray sources from 7 to 15 ?m size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

  14. Comparison of GATE/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV

    NASA Astrophysics Data System (ADS)

    Maigne, L.; Perrot, Y.; Schaart, D. R.; Donnarieix, D.; Breton, V.

    2011-02-01

    The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between 15 keV and 20 MeV by means of GATE 6.0, which makes use of the GEANT4 version 9.2 Standard Electromagnetic Physics Package. The results are compared to the well-validated codes EGSnrc and MCNP4C. It is shown that recent improvements made to the GEANT4/GATE software result in significantly better agreement with the other codes. We furthermore illustrate several issues of general interest to GATE and GEANT4 users who wish to perform accurate simulations involving electrons. Provided that the electron step size is sufficiently restricted, GATE 6.0 and EGSnrc dose point kernels are shown to agree to within less than 3% of the maximum dose between 50 keV and 4 MeV, while pencil beam kernels are found to agree to within less than 4% of the maximum dose between 15 keV and 20 MeV.

  15. Nonthermal X-rays from low-energy cosmic rays: application to the 6.4 keV line emission from the Arches cluster region

    NASA Astrophysics Data System (ADS)

    Tatischeff, V.; Decourchelle, A.; Maurin, G.

    2012-10-01

    Context. The iron K? line at 6.4 keV provides a valuable spectral diagnostic in several fields of X-ray astronomy. The line often results from the reprocessing of external hard X-rays by a neutral or low-ionized medium, but it can also be excited by impacts of low-energy cosmic rays. Aims: This paper aims to provide signatures allowing identification of radiation from low-energy cosmic rays in X-ray spectra showing the 6.4 keV Fe K? line. Methods: We study in detail the production of nonthermal line and continuum X-rays by interaction of accelerated electrons and ions with a neutral ambient gas. Corresponding models are then applied to XMM-Newton observations of the X-ray emission emanating from the Arches cluster region near the Galactic center. Results: Bright 6.4 keV Fe line structures are observed around the Arches cluster. This emission is very likely produced by cosmic rays. We find that it can result from the bombardment of molecular gas by energetic ions, but probably not by accelerated electrons. Using a model of X-ray production by cosmic-ray ions, we obtain a best-fit metallicity of the ambient medium of 1.7 ± 0.2 times the solar metallicity. A large flux of low-energy cosmic ray ions could be produced in the ongoing supersonic collision between the star cluster and an adjacent molecular cloud. We find that a particle acceleration efficiency in the resulting shock system of a few percent would give enough power in the cosmic rays to explain the luminosity of the nonthermal X-ray emission. Depending on the unknown shape of the kinetic energy distribution of the fast ions above ~1 GeV nucleon-1, the Arches cluster region may be a source of high-energy ?-rays detectable with the Fermi Gamma-ray Space Telescope. Conclusions: At present, the X-ray emission prominent in the 6.4 keV Fe line emanating from the Arches cluster region probably offers the best available signature for a source of low-energy hadronic cosmic rays in the Galaxy. Appendices are available in electronic form at http://www.aanda.org

  16. Bremsstrahlung energy spectra from electrons with kinetic energy 1 keV10 GeV incident on screened nuclei and orbital electrons of neutral atoms with Z = 1--100

    Microsoft Academic Search

    S. M. Seltzer; M. J. Berger

    1986-01-01

    A comprehensive set of bremsstrahlung cross sections (differential in the energy of the emitted photons) is tabulated. The set includes results for electrons with energies from 1 keV to 10 GeV incident on neutral atoms with atomic numbers Z = 1 to 100. For bremsstrahlung in the Coulomb field of the atomic nucleus, use was made of (a) results of

  17. Measurement of X-ray mass attenuation coefficients in biological and geological samples in the energy range of 7-12keV.

    PubMed

    Trunova, Valentina; Sidorina, Anna; Kriventsov, Vladimir

    2014-10-17

    Information about X-ray mass attenuation coefficients in different materials is necessary for accurate X-ray fluorescent analysis. The X-ray mass attenuation coefficients for energy of 7-12keV were measured in biological (Mussel and Oyster tissues, blood, hair, liver, and Cabbage leaves) and geological (Baikal sludge, soil, and Alaskite granite) samples. The measurements were carried out at the EXAFS Station of Siberian Synchrotron Radiation Center (VEPP-3). Obtained experimental mass attenuation coefficients were compared with theoretical values calculated for some samples. PMID:25464176

  18. Energy loss of keV fluorine ions scattered off a missing-row reconstructed Au(110) surface under grazing incidence

    SciTech Connect

    Chen, L. [Institut des Sciences Moleculaires (Unite Mixte de Recherche CNRS Universite, UMR 8214), bat 351, Universite de Paris Sud, Orsay F-91405 (France); School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000 (China); Shen, J.; Esaulov, V. A. [Institut des Sciences Moleculaires (Unite Mixte de Recherche CNRS Universite, UMR 8214), bat 351, Universite de Paris Sud, Orsay F-91405 (France); Valdes, J. E.; Vargas, P. [Department of Physics, Universidad Tecnica Federico Santa Maria, Valparaiso, Casilla 110-V (Chile)

    2011-03-15

    A joint experimental and theoretical study of energy loss is presented for 1-to-4-keV fluorine negative ions in grazing scattering on a missing-row reconstructed Au(110) surface. Measurements of energy losses for various azimuthal orientations of the crystal have been performed by means of a time-of-flight method with a pulsed beam. The dependence of the fraction of surviving negative ions on azimuthal angles, was determined. Our energy-loss data are discussed in light of trajectory and stopping-power calculations, where the explicit inclusion of the nonuniform electron density at the surface provides good agreement with the experimental data. The simulation allows us to delineate various trajectory classes that correspond to different contributions in the energy-loss spectra for various azimuthal orientations of the surface.

  19. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV

    NASA Astrophysics Data System (ADS)

    Buhr, H.; Büermann, L.; Gerlach, M.; Krumrey, M.; Rabus, H.

    2012-12-01

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given.

  20. Measurement of the mass energy-absorption coefficient of air for x-rays in the range from 3 to 60 keV.

    PubMed

    Buhr, H; Büermann, L; Gerlach, M; Krumrey, M; Rabus, H

    2012-12-21

    For the first time the absolute photon mass energy-absorption coefficient of air in the energy range of 10 to 60 keV has been measured with relative standard uncertainties below 1%, considerably smaller than those of up to 2% assumed for calculated data. For monochromatized synchrotron radiation from the electron storage ring BESSY II both the radiant power and the fraction of power deposited in dry air were measured using a cryogenic electrical substitution radiometer and a free air ionization chamber, respectively. The measured absorption coefficients were compared with state-of-the art calculations and showed an average deviation of 2% from calculations by Seltzer. However, they agree within 1% with data calculated earlier by Hubbell. In the course of this work, an improvement of the data analysis of a previous experimental determination of the mass energy-absorption coefficient of air in the range of 3 to 10 keV was found to be possible and corrected values of this preceding study are given. PMID:23192280

  1. Studies on effective atomic numbers and electron densities in amino acids and sugars in the energy range 30 1333 keV

    NASA Astrophysics Data System (ADS)

    Gowda, Shivalinge; Krishnaveni, S.; Gowda, Ramakrishna

    2005-10-01

    The effective atomic numbers and electron densities of the amino acids glycine, alanine, serine, valine, threonine, leucine, isoleucine, aspartic acid, lysine, glutamic acid, histidine, phenylalanine, arginine, tyrosine, tryptophane and the sugars arabinose, ribose, glucose, galactose, mannose, fructose, rhamnose, maltose, melibiose, melezitose and raffinose at the energies 30.8, 35.0, 81.0, 145, 276.4, 302.9, 356, 383.9, 661.6, 1173 and 1332.5 keV were calculated by using the measured total attenuation cross-sections. The interpolations of total attenuation cross-sections for photons of energy E in elements of atomic number Z was performed using the logarithmic regression analysis of the XCOM data in the photon energy region 30-1500 keV. The best-fit coefficients obtained by a piece wise interpolation method were used to find the effective atomic number and electron density of the compounds. These values are found to be in good agreement with the theoretical values calculated based on XCOM data.

  2. Fine pitch CdTe-based Hard-X-ray polarimeter performance for space science in the 70-300 keV energy range

    E-print Network

    Antier, S; Ferrando, P

    2015-01-01

    X-rays astrophysical sources have been almost exclusively characterized through imaging, spectroscopy and timing analysis. Nevertheless, more observational parameters are needed because some radiation mechanisms present in neutrons stars or black holes are still unclear. Polarization measurements will play a key role in discrimination between different X-ray emission models. Such a capability becomes a mandatory requirement for the next generation of high-energy space proposals. We have developed a CdTe-based fine-pitch imaging spectrometer, Caliste, able to respond to these new requirements. With a 580-micron pitch and 1 keV energy resolution at 60 keV, we are able to accurately reconstruct the polarization angle and polarization fraction of an impinging flux of photons which are scattered by 90{\\deg} after Compton diffusion within the crystal. Thanks to its high performance in both imaging and spectrometry, Caliste turns out to be a powerful device for high-energy polarimetry. In this paper, we present the ...

  3. A Review of X-ray Diagnostic Calibrations in the 2 to 100 keV Region Using the High Energy X-ray Calibration Facility (HEX)

    SciTech Connect

    Ali, Zaheer; Pond, T; Buckles, R A; Maddox, B R; Chen, C D; DeWald, E L; Izumi, N; Stewart, R

    2010-05-19

    The precise and accurate measurement of X-rays in the 2 keV to 100 keV region is crucial to the understanding of HED plasmas and warm dense matter in general. With the emergence of inertially confined plasma facilities as the premier platforms for ICF, laboratory astrophysics, and national security related plasma experiments, the need to calibrate diagnostics in the high energy X-ray regime has grown. At National Security Technologies High Energy X-ray Calibration Facility (HEX) in Livermore, California, X-ray imagers, filter-fluorescer spectrometers, crystal spectrometers, image plates, and nuclear diagnostics are calibrated. The HEX can provide measurements of atomic line radiation, X-ray flux (accuracy within 10%), and X-ray energy (accuracy within 1%). The HEX source is comprised of a commercial 160 kV X-ray tube, a fluorescer wheel, a filter wheel, and a lead encasement. The X-ray tube produces a Tungsten bremsstrahlung spectrum which causes a foil to fluoresce line radiation. To minimize bremsstrahlung in the radiation for calibration we also provide various foils as filters. For experimental purposes, a vacuum box capable of 10{sup -7} Torr, as well as HPGe and CdTe radiation detectors, are provided on an optical table. Most geometries and arrangements can be changed to meet experimental needs.

  4. Measurement of the x-ray mass attenuation coefficients of gold in the 38?50-keV energy range

    SciTech Connect

    Islam, M.T.; Rae, N.A.; Glover, J.L.; Barnea, Z.; de Jonge, M.D.; Tran, C.Q.; Wang, J.; Chantler, C.T. (Melbourne)

    2010-11-12

    We used synchrotron x rays to measure the x-ray mass attenuation coefficients of gold at nine energies from 38 to 50 keV with accuracies of 0.1%. Our results are much more accurate than previous measurements in this energy range. A comparison of our measurements with calculated mass attenuation coefficients shows that our measurements fall almost exactly midway between the XCOM and FFAST calculated theoretical values, which differ from one another in this energy region by about 4%, even though the range includes no absorption edge. The consistency and accuracy of these measurements open the way to investigations of the x-ray attenuation in the region of the L absorption edge of gold.

  5. 950 keV X-Band Linac For Material Recognition Using Two-Fold Scintillator Detector As A Concept Of Dual-Energy X-Ray System

    SciTech Connect

    Lee, Kiwoo; Natsui, Takuya; Hirai, Shunsuke; Uesaka, Mitsuru [University of Tokyo, 2-22 Tokai-mura, Ibaraki-ken 319-1188 (Japan); Hashimoto, Eiko [Japan atomic energy agency (JAEA), 4-49 Muramatsu Tokai-mura, Ibaraki-ken (Japan)

    2011-06-01

    One of the advantages of applying X-band linear accelerator (Linac) is the compact size of the whole system. That shows us the possibility of on-site system such as the custom inspection system in an airport. As X-ray source, we have developed X-band Linac and achieved maximum X-ray energy 950 keV using the low power magnetron (250 kW) in 2 {mu}s pulse length. The whole size of the Linac system is 1x1x1 m{sup 3}. That is realized by introducing X-band system. In addition, we have designed two-fold scintillator detector in dual energy X-ray concept. Monte carlo N-particle transport (MCNP) code was used to make up sensor part of the design with two scintillators, CsI and CdWO4. The custom inspection system is composed of two equipments: 950 keV X-band Linac and two-fold scintillator and they are operated simulating real situation such as baggage check in an airport. We will show you the results of experiment which was performed with metal samples: iron and lead as targets in several conditions.

  6. Effective cross sections for fission of U 233 , U 235 , Pu 239 and Pu 240 by neutrons with energies from 30 kev to 5 Mev

    Microsoft Academic Search

    G. A. Dorofeev; Yu. P. Dobrynin

    1957-01-01

    Measurements have been made of the absolute values of the effective fission cross sections in U233, U235, Pu239 and Pu240, using as photoneutron sources Sb + Be (~ 30 kev), Na + D2O (~ 250 kev), Na + Be (~ 900 kev), a source with a simulated fission-neutron spectrum and Po-a-Be. The fission cross sections for 30 kev-neutrons are 3.06

  7. Remote Sensing of Icy Galilean Moon Surface and Atmospheric Composition Using Low Energy (1 eV-4 keV) Neutral Atom Imaging

    NASA Technical Reports Server (NTRS)

    Collier, M. R.; Sittler, E.; Chornay, D.; Cooper, J. F.; Coplan, M.; Johnson, R. E.

    2004-01-01

    We describe a low energy neutral atom imager suitable for composition measurements Europa and other icy Galilean moons in the Jovian magnetosphere. This instrument employs conversion surface technology and is sensitive to either neutrals converted to negative ions, neutrals converted to positive ions and the positive ions themselves depending on the power supply. On a mission such as the Jupiter Icy Moons Orbiter (JIMO), two back-to-back sensors would be flown with separate power supplies fitted to the neutral atom and iodneutral atom sides. This will allow both remote imaging of 1 eV < E < 4 keV neutrals from icy moon surfaces and atmospheres, and in situ measurements of ions at similar energies in the moon ionospheres and Jovian magnetospheric plasma. The instrument provides composition measurements of the neutrals and ions that enter the spectrometer with a mass resolution dependent on the time-of-flight subsystem and capable of resolving molecules. The lower energy neutrals, up to tens of eV, arise from atoms and molecules sputtered off the moon surfaces and out of the moon atmospheres by impacts of more energetic (keV to MeV) ions from the magnetosphere. Direct Simulation Monte Carlo (DSMC) models are used to convert measured neutral abundances to compositional distributions of primary and trace species in the sputtered surfaces and atmospheres. The escaping neutrals can also be detected as ions after photo- or plasma-ionization and pickup. Higher energy, keV neutrals come from charge exchange of magnetospheric ions in the moon atmospheres and provide information on atmospheric structure. At the jovicentric orbits of the icy moons the presence of toroidal gas clouds, as detected at Europa's orbit, provide M e r opportunities to analyze both the composition of neutrals and ions originating from the moon surfaces, and the characteristics of magnetospheric ions interacting with neutral cloud material. Charge exchange of low energy ions near the moons, and directional distributions of the resultant neutrals, allow indirect global mapping of magnetic field structures around the moons. Temporal variation of the magnetic structures can be linked to induced magnetic fields associated with subsurface oceans.

  8. Neutron capture resonances in /sup 56/Fe and /sup 58/Fe in the energy range from 10 to 100 keV

    SciTech Connect

    Kappeler, F.; Hong, L.D.; Wisshak, K.

    1983-07-01

    The neutron capture cross sections of /sup 56/Fe and /sup 58/Fe have been measured in the energy range from 10 to 250 keV relative to the gold standard. A pulsed 3-MV Van de Graaff accelerator and the /sup 7/Li(p,n) reaction served as a neutron source. Capture gamma rays were detected by two C/sub 6/D/sub 6/ detectors, which were operated in coincidence and anticoincidence modes. Two-dimensional data acquisition allowed the off-line application of the pulse height weighting technique. The samples were located at a 60-cm flight path. The total time resolution was 1.2 ns allowing an energy resolution of 2 ns/m. The experimental setup was optimized with respect to low background and low neutron sensitivity. The additional 4-cm flight path from the sample to the detector was sufficient to discriminate against the capture of sample scattered neutrons by the additional time of flight. In this way reliable results were obtained even for the strong s-wave resonances of both isotopes. The experimental capture yield was analyzed with the FANAC code. The energy resolution allowed extraction of resonance parameters in the energy range from 10 to 100 keV. Individual systematic uncertainties were found to range between 5 and 10% while the statistical uncertainty is 3 to 5% for most resonances. A comparison to other results exhibits systematic differences of 7 to 11% for /sup 56/Fe. The present results for /sup 58/Fe differ up to 50% from the only other measurement for this isotope.

  9. Absolute differential cross sections for elastic and inelastic electron scattering from benzene with 1 kev impact energy

    Microsoft Academic Search

    H. M. Boechat-Roberty; M. L. M. Rocco; C. A. Lucas; G. G. B. de Souza

    2004-01-01

    The absolute generalized oscillator strength and absolute inelastic differential cross section have been determined, as a function of the momentum transfer, for the 1E1u + 1B1u larr 1Ag transition in the benzene molecule. A previously described electron energy-loss spectrometer, featuring a Wien-filter velocity analyser, has been used. Employing 1000 eV incident electron energy and 1.0 eV energy resolution, absolute oscillator

  10. Absolute differential cross sections for elastic and inelastic electron scattering from benzene with 1 kev impact energy

    Microsoft Academic Search

    H M Boechat-Roberty; M L M Rocco; C A Lucas; G G B de Souza

    2004-01-01

    The absolute generalized oscillator strength and absolute inelastic differential cross section have been determined, as a function of the momentum transfer, for the 1E1u + 1B1u ? 1Ag transition in the benzene molecule. A previously described electron energy-loss spectrometer, featuring a Wien-filter velocity analyser, has been used. Employing 1000 eV incident electron energy and 1.0 eV energy resolution, absolute oscillator

  11. A semi-empirical approach to analyze the activities of cylindrical radioactive samples using gamma energies from 185 to 1764 keV.

    PubMed

    Huy, Ngo Quang; Binh, Do Quang

    2014-12-01

    This work suggests a method for determining the activities of cylindrical radioactive samples. The self-attenuation factor was applied for providing the self-absorption correction of gamma rays in the sample material. The experimental measurement of a (238)U reference sample and the calculation using the MCNP5 code allow obtaining the semi-empirical formulae of detecting efficiencies for the gamma energies ranged from 185 to 1764keV. These formulae were used to determine the activities of the (238)U, (226)Ra, (232)Th, (137)Cs and (40)K nuclides in the IAEA RGU-1, IAEA-434, IAEA RGTh-1, IAEA-152 and IAEA RGK-1 radioactive standards. The coincidence summing corrections for gamma rays in the (238)U and (232)Th series were applied. The activities obtained in this work were in good agreement with the reference values. PMID:25113537

  12. Liquid helium cryostat with internal fluorescence detection for x-ray absorption studies in the 2–6 keV energy region

    PubMed Central

    Holman, Karen L. McFarlane; Latimer, Matthew J.; Yachandra, Vittal K.

    2014-01-01

    X-ray absorption spectroscop (XAS) in the intermediate x-ray region (2–6 keV) for dilute biological samples has been limited because of detector/flux limitations and inadequate cryogenic instrumentation. We have designed and constructed a new tailpiece/sample chamber for a commercially available liquid helium cooled cryostat which overcomes difficulties related to low fluorescence signals by using thin window materials and incorporating an internal photodiode detector. With the apparatus, XAS data at the Cl, S, and Ca K edges have been collected on frozen solutions and biological samples at temperatures down to 60 K. A separate chamber has been incorporated for collecting room-temperature spectra of standard compounds (for energy calibration purposes) which prevents contamination of the cryostat chamber and allows the sample to remain undisturbed, both important concerns for studying dilute and radiation-sensitive samples. PMID:25057214

  13. Production of sow multiple-charged ions in rare gases ions and atoms collisions at low energy (1-4 keV).

    SciTech Connect

    Kikiani, B.I.; Lomsadze, R.A. [Tbilisi State Univ., Georgia (Russian Federation)

    1994-12-31

    The energy dependence of the absolute values of summed ({sigma}) and partial ({sigma}{sub n}) cross-sections of target gas ions production in rare gases ions and atoms collisions was defined by potential method, supplemented by magnetic mass-analysis. Here {sigma} and {sigma}{sub n} are connected by relation: {sigma}{sub n}={sigma}/(2(1+1/{alpha}{sub n})), where {alpha}{sub n}=I{sub n}/{Sigma}{sub n}I{sub n} is part of n-charged state ions. The authors results show, that practically there are no ions produced with n>2. For symmetrical pairs (like He{sup +}-He, Ne{sup +}-Ne) {alpha}{sub 2{minus}}<0.1%, for He{sup +}-Ne, Ar{sup +}-Kr, Kr{sup +}-Xe value of {alpha}{sub 2} is {approximately}1% ({sigma}{sub 2}{approximately}<10{sup {minus}18}cm{sup 2}), for He{sup +}-Kr, He{sup +}-Xe this value increases with colliding energy and at E=4 keV reaches {approximately} 3%. However, for He{sub +}, Ne{sup +}-Ar, Kr, Xe {alpha}{sub 2} is significant ({alpha}{sub 2}{approximately}20-25%, {sigma}{sub 2}{approximately} 2 {center_dot} 10{sup {minus}17}cm{sup 2} for He{sup +}-Ar at E=4 keV). Analysis of the correlation diagram for colliding particle systems (MS) shows, that double ionization process in these cases is realizing by electron capture process at same time excitation of autoionization states of target gas ions: A{sup +}+B{sup 0}{yields}A{sup 0}+B{sup +*}{yields}A{sup 0}+B{sup 2+}+e.

  14. plutonium isotopic analysis in the 30 KeV to 210 KeV range

    SciTech Connect

    Vo, Duc T.; Li, T. K. (Tien K.)

    2001-01-01

    Low-Energy Gamma-ray Spectroscopy (LEGS) is a nondestructive assay (NDA) technique developed in the 1980s. In 1999, it was modified to include a physical-based model for the energy dependent efficiency. It uses the gamma rays in the energy range from approximately 30 keV to 210 keV, except the 100-keV region. This energy region provides intense, well-separated gamma rays from the principal isotopes of plutonium. For applications involving small quantities (mg to g) of freshly separated plutonium in various chemical forms, it is ideally suited for accurate real-time or near real-time isotopic analysis. Since the last modification, LEGS has been incorporated into the FRAM code (Fixed-energy Response-function Analysis with Multiple efficiency), version 4. FRAM v4 is capable of analyzing the peaks in the whole energy range from 30 keV to 1 MeV, including the X-ray region. The new capability of analyzing the peaks in the 100-keV region greatly enhances the plutonium analysis in the 30 keV to 2 10 keV ranges of the traditional LEGS. We now can analyze both the freshly separated and aged plutonium with greater accuracy.

  15. Ion Beam Materials Analysis and Modifications at keV to MeV Energies at the University of North Texas

    NASA Astrophysics Data System (ADS)

    Rout, Bibhudutta; Dhoubhadel, Mangal S.; Poudel, Prakash R.; Kummari, Venkata C.; Lakshantha, Wickramaarachchige J.; Manuel, Jack E.; Bohara, Gyanendra; Szilasi, Szabolcs Z.; Glass, Gary A.; McDaniel, Floyd D.

    2014-02-01

    The University of North Texas (UNT) Ion Beam Modification and Analysis Laboratory (IBMAL) has four particle accelerators including a National Electrostatics Corporation (NEC) 9SDH-2 3 MV tandem Pelletron, a NEC 9SH 3 MV single-ended Pelletron, and a 200 kV Cockcroft-Walton. A fourth HVEC AK 2.5 MV Van de Graaff accelerator is presently being refurbished as an educational training facility. These accelerators can produce and accelerate almost any ion in the periodic table at energies from a few keV to tens of MeV. They are used to modify materials by ion implantation and to analyze materials by numerous atomic and nuclear physics techniques. The NEC 9SH accelerator was recently installed in the IBMAL and subsequently upgraded with the addition of a capacitive-liner and terminal potential stabilization system to reduce ion energy spread and therefore improve spatial resolution of the probing ion beam to hundreds of nanometers. Research involves materials modification and synthesis by ion implantation for photonic, electronic, and magnetic applications, micro-fabrication by high energy (MeV) ion beam lithography, microanalysis of biomedical and semiconductor materials, development of highenergy ion nanoprobe focusing systems, and educational and outreach activities. An overview of the IBMAL facilities and some of the current research projects are discussed.

  16. Reevaluation of 58Ni and 60Ni Resonance Parameters in the Energy Range Thermal to 800 keV

    SciTech Connect

    Derrien, Herve [ORNL; Leal, Luiz C [ORNL; Guber, Klaus H [ORNL; Wiarda, Dorothea [ORNL; Arbanas, Goran [ORNL

    2009-01-01

    The previous 58Ni and 60Ni set of resonance parameters (ENDF/B-VII-0, JEFF-3, etc.) was based on the SAMMY analysis of Oak Ridge National Laboratory neutron transmission, scattering cross section and capture cross section measurements by C. M. Perey et al. The present results were obtained by adding to the SAMMY experimental data base the capture cross sections measured recently at the Oak Ridge Linear Electron Accelerator by Guber et al. and the Geel Electron Linear Accelerator very high-resolution neutron transmission measurements performed by Brusegan et al. A complete resonance parameter covariance matrix (RPCM) was obtained from the SAMMY analysis of the experimental database. The data sets were made consistent, when needed, by adjusting the neutron energy scales, the normalization coefficients, and the background corrections. The RPCM allows the calculation of the cross section uncertainties due mainly to statistical errors in the experimental data. The systematic uncertainties of the experimental data, estimated from the preliminary analyses of the experimental database, were taken into account in the cross section covariance matrix (CSCM) for total, scattering, and capture cross sections. The diagonal elements of the CSCM were obtained by quadratic combination of the different components of the uncertainties. Because of a lack of experimental information, the energy correlations were not obtained, and a value of 0.5 was arbitrarily taken for all the CSCM nondiagonal elements.

  17. Measurement of the 13C(?, n)16O reaction at astrophysical energies using the Trojan Horse Method. Focus on the -3 keV sub-threshold resonance

    NASA Astrophysics Data System (ADS)

    La Cognata, M.; Spitaleri, C.; Trippella, O.; Kiss, G. G.; Rogachev, G. V.; Mukhamedzhanov, A. M.; Avila, M.; Guardo, G. L.; Koshchiy, E.; Kuchera, A.; Lamia, L.; Puglia, S. M. R.; Romano, S.; Santiago, D.; Spartà, R.

    2014-03-01

    Most of the nuclei in the mass range 90 ? A ? 208 are produced through the so-called s-process, namely through a series of neutron capture reactions on seed nuclei followed by ?-decays. The 13C(?, n)16O reaction is the neutron source for the main component of the s-process. It is active inside the helium-burning shell of asymptotic giant branch stars, at temperatures ? 108 K, corresponding to an energy interval of 140 - 230 keV. In this region, the astrophysical S(E)-factor is dominated by the -3 keV sub-threshold resonance due to the 6.356 MeV level in 17O. Direct measurements could not soundly establish its contribution owing to the cross section suppression at astrophysical energies determined by the Coulomb barrier between interacting nuclei. Indirect measurements and extrapolations yielded inconsistent results, calling for further investigations. The Trojan Horse Method turns out to be very suited for the study of the 13C(?, n)16O reaction as it allows us to access the low as well as the negative energy re- gion, in particular in the case of resonance reactions. We have applied the Trojan HorseMethod to the 13C(6Li, n16O)d quasi-free reaction. By using the modified R-matrix approach, the asymptotic normalization coefficient {( {tilde C{? 13{{C}}}17{{O(1/}{{{2}}{ + }}{{)}}}} )^2} of the 6.356 MeV level has been deduced as well as the n-partial width, allowing to attain an unprecedented accuracy for the 13C(?, n)16O astrophysical factor. A preliminary analysis of a partial data set has lead to {( {tilde C{? 13{{C}}}17{{O(1/}{{{2}}{ + }}{{)}}}} )^2} = 6.7 - 0.6 + 0.9 {{f}}{{{m}} - 1}, slightly larger than the values in the literature, determining a 13C(?, n)16O reaction rate in agreement with the most results in the literature at ˜ 108 K, with enhanced accuracy thanks to this innovative approach.

  18. Atom penetration from a thin film into the substrate during sputtering by polyenergetic Ar{sup +} ion beam with mean energy of 9.4 keV

    SciTech Connect

    Kalin, B.A.; Gladkov, V.P.; Volkov, N.V.; Sabo, S.E. [Moscow Engineering Physics Inst. (Russian Federation)

    1995-12-31

    Penetration of alien atoms (Be, Ni) into Be, Al, Zr, Si and diamond was investigated under Ar{sup +} ion bombardment of samples having thermally evaporated films of 30--50 nm. Sputtering was carried out using a wide energy spectrum beam of Ar{sup +} ions of 9.4 keV to dose D = 1 {times} 10{sup 16}--10{sup 19} ion/cm{sup 2}. Implanted atom distribution in the targets was measured by Rutherford backscattering spectrometry (RBS) of H{sup +} and He{sup +} ions with energy of 1.6 MeV as well as secondary ion mass-spectrometry (SIMS). During the bombardment, the penetration depth of Ar atoms increases with dose linearly. This depth is more than 3--20 times deeper than the projected range of bombarding ions and recoil atoms. This is a deep action effect. The analysis shows that the experimental data for foreign atoms penetration depth are similar to the data calculated for atom migration through the interstitial site in a field of internal (lateral) compressive stresses created in the near-surface layer of the substrate as a result of implantation. Under these experimental conditions atom ratio r{sub i}/r{sub m} (r{sub i} -- radius of dopant, r{sub m} -- radius target of substrate) can play a principal determining role.

  19. Energy dependent response of the Fricke gel dosimeter prepared with 270 Bloom gelatine for photons in the energy range 13.93 keV-6 MeV

    NASA Astrophysics Data System (ADS)

    Cavinato, C. C.; Campos, L. L.

    2010-07-01

    The spectrophotometric energy dependent response to photons with effective energies between 13.93 keV and 6 MeV of the Fricke xylenol gel (FXG) dosimeter developed at IPEN, prepared using 270 Bloom gelatine, was evaluated in order to verify the possible dosimeter application in other medicine areas in addition to radiosurgery, for example, breast radiotherapy and blood bags radiosterilization. Other dosimetric characteristics were also evaluated. The obtained results indicate that the FXG dosimeter can contribute to dosimetry in different medical application areas including magnetic resonance imaging (MRI) evaluation technique that permits three-dimensional (3D) dose distribution evaluation.

  20. INTEGRAL IGR J18135-1751=HESS J1813-178: A new cosmic high energy accelerator from keV to TeV

    E-print Network

    P. Ubertini; L. Bassani; A. Malizia; A. Bazzano; A. J. Bird; A. J. Dean; A. De Rosa; F. Lebrun; L. Moran; M. Renaud; J. Stephen; R. Terrier; R. Walter

    2005-07-14

    We report the discovery of a soft gamma ray source, namely IGR J18135-1751, detected with the IBIS imager on board the INTEGRAL satellite. The source is persistent and has a 20-100 keV luminosity of $\\sim$5.7 $\\times$ 10$^{34}$ erg s$^{-1}$ (assuming a distance of 4kpc). This source is coincident with one of the eight unidentified objects recently reported by the HESS collaboration as part of the first TeV survey of the inner part of the Galaxy. Two of these new sources found along the Galactic plane, HESS J1813-178 and HESS J1614-518, have no obvious lower energy counterpart, a fact that motivated the suggestion that they might be dark cosmic ray accelerators. HESS J1813-178 has a strongly absorbed X-ray counterpart, the ASCA source AGPS273.4-17.8, showing a power law spectrum with photon index $\\sim$ 1.8 and a total (galactic plus intrinsic) absorption corresponding to N$_H$ $\\sim$5 $\\times$ 10$^{22}$ cm$^{-2}$. We hypothesize that the source is a pulsar wind nebula embedded in its supernova remnant. The lack of X/gamma-ray variability, the radio morphology and the ASCA spectrum are all compatible with this interpretation. In any case we rule out the hypothesis that HESS J1813-178 belongs to a new class of TeV objects or that it is a cosmic "dark particle" accelerator.

  1. Low energy (10eV to 10 keV) equatorial particle fluxes and soft particle fluxes near the equator

    NASA Technical Reports Server (NTRS)

    Winningham, J. D.; Heikkila, W. J.

    1974-01-01

    Several spectra are shown that represent one rotation of ISIS-1. Spectra 1, 2, 3, represent particles moving down the field line into northern ionosphere and spectra 4, 5, 6 represent particles moving up field lines towards the magnetic equator. The former are direct fluxes and the latter are albedo fluxes. The spectra observed are remarkably similar to these observed in the auroral zone. The direct fluxes exhibit a relative maximum in the few keV range and the albedo a power low spectrum with increased fluxes at low energies. Examination of concurrent topside sounder data on ISIS-1 revealed a positive correlation between a region of turbulent ionosphere and particle fluxes. This ionospheric condition is referred to as equatorial spread F and has been studied extensively with bottomside ionospheric sounders and backscatter radars. The perigee of ISIS crossed the magnetic equator at four local times (0400, 1000, 1600, 2100) during the lifetime of the particle spectrometer. No fluxes were observed at 0400 and 1000 local time. At 1600 a few instances of particles were observed. At 2100 essentially all passes included detectable equatorial fluxes. This is in agreement with the frequency of occurence of equatorial spread F.

  2. The effects of energy-loss straggling and elastic scattering models on Monte Carlo calculations of dose distribution functions for 10 keV to 1 MeV incident electrons in water

    NASA Astrophysics Data System (ADS)

    Bousis, C.; Emfietzoglou, D.; Nikjoo, H.; Hadjidoukas, P.; Pathak, A.

    2009-05-01

    Accurate simulation of the transport and energy-loss of energetic electrons is an important step in modeling ion-induced effects in materials. Dose distribution functions (or so-called dose point kernels, DPKs) represent one of the most basic and useful quantities for characterizing the spatial distribution of energy deposition in matter. In the present work we investigate the effect on DPK of various models for the elastic scattering cross-section and energy-loss straggling distribution widely used in Monte Carlo simulation of electron transport above a few keV. Our findings indicate that, overall, the DPK is not very sensitive to the examined physical models, except at the tail of the distribution where a strong dependence is observed. The present comparison can be useful for avoiding systematic errors in the simulation of electron transport at primary energies from several keV to a few MeV and to suggest further improvement in the existing codes.

  3. NEUTRON ACTIVATION CROSS SECTIONS AT 25 Kev

    Microsoft Academic Search

    Rex Booth; William Ball; Malcolm MacGregor

    1958-01-01

    Neutron activation cross sections have been measured at 25 kev for 31 ; isotopes. An Sb-Be photoneutron source was used, and thermal activations served ; to calibrate the beta- and gamma-detector efficiencies. The cross sections were ; measnred relative to iodine. A comparison was made between measured cross ; sections and predictions based on known low-energy resonance parameters. (auth);

  4. Neutron Activation Cross Sections at 25 kev

    Microsoft Academic Search

    Rex Booth; William P. Ball; Malcolm H. MacGregor

    1958-01-01

    Neutron activation cross sections have been measured at 25 kev for 31 isotopes. An Sb-Be photoneutron source was used, and thermal activations served to calibrate the beta- and gamma-detector efficiencies. The cross sections were measured relative to iodine. A comparison was made between measured cross sections and predictions based on known low-energy resonance parameters.

  5. Multilayer diffraction at 104 keV

    NASA Technical Reports Server (NTRS)

    Krieger, Allen S.; Blake, Richard L.; Siddons, D. P.

    1993-01-01

    We have measured the diffraction peak of a W:Si synthetic multilayer reflector at 104 keV using the High Energy Bonse-Hart Camera at the X-17B hard X-ray wiggler beam line of the National Synchrotron Light Source at Brookhaven National Laboratory. The characteristics of the diffraction peak are described and compared to theory.

  6. Characterization of Low-Energy (6-30 keV) Response of Polish TLDs (MTS-N, MCP-N) with Synchrotron Radiation and Determination of Some Fundamental TLD Quantities

    SciTech Connect

    Ipe, Nisy E.

    1998-11-17

    Relative to 137Cs gamma rays, the response of MTS-N (NatLiF:Mg,Ti-0.04 cm thick) increased from 0.4 to 1.4 between x-ray energies of 6 and 30 keV and that of MCP-N (NatLif:Mg, Cu, P-0.04 cm thick) increased from 0.02 to 1.2 between 6 and 26 keV. A mathematical model for TLD response was used with measured responses to determine overall TLD efficiency C(k) and efficiency relative to 137Cs. The effective energy attenuation coefficient {mu}(k) and light attenuation coefficient f were also determined experimentally. The relative efficiency of MTS-N increased from 0.66 to 1.30 between 6 and 30 keV and that of MCP-N increased from 0.37 to 0.99 between 6 and 26 keV.

  7. Characterization of Low-Energy (6-30 keV) Response of Polish TLDs (MTS-N, MCP-N) with Synchrotron Radiation and Determination of Some Fundamental TLD Quantities

    SciTech Connect

    Ipe, Nisy E.

    1998-11-17

    Relative to 137Cs gamma rays, the response of MTS-N (NatLiF:Mg,Ti-0.04 cm thick) increased from 0.4 to 1.4 between x-ray energies of 6 and 30 keV and that of MCP-N (NatLif:Mg, Cu, P-0.04 cm thick) increased from 0.02 to 1.2 between 6 and 26 keV. A mathematical model for TLD response was used with measured responses to determine overall TLD efficiency C(k) and efficiency relative to 137Cs. The effective energy attenuation coefficient [mu](k) and light attenuation coefficient f were also determined experimentally. The relative efficiency of MTS-N increased from 0.66 to 1.30 between 6 and 30 keV and that of MCP-N increased from 0.37 to 0.99 between 6 and 26 keV.

  8. Demonstration of direct energy recovery of full energy ions at 40 keV on a PLT\\/ISX beam system

    Microsoft Academic Search

    W. L. Stirling; G. C. Barber; W. K. Dagenhart; R. R. Feezell; W. L. Gardner; H. H. Haselton; J. Kim; M. Menon; N. S. Ponte; C. C. Tsai

    1980-01-01

    The desire for multisecond beams in the 80 keV\\/nucleon energy range at 10 MW\\/module emphasized the need for technological advances in several areas. At such beam energies, as much as 75 percent of the initial beam energy is retained in the unneutralized ion components. As a result, two questions immediately come to mind: how can one dispose of this energy;

  9. Structure determination from XAFS using high-accuracy measurements of x-ray mass attenuation coefficients of silver, 11 keV-28 keV, and development of an all-energies approach to local dynamical analysis of bond length, revealing variation of effective thermal contributions across the XAFS spectrum.

    PubMed

    Tantau, L J; Chantler, C T; Bourke, J D; Islam, M T; Payne, A T; Rae, N A; Tran, C Q

    2015-07-01

    We use the x-ray extended range technique (XERT) to experimentally determine the mass attenuation coefficient of silver in the x-ray energy range 11 kev-28 kev including the silver K absorption edge. The results are accurate to better than 0.1%, permitting critical tests of atomic and solid state theory. This is one of the most accurate demonstrations of cross-platform accuracy in synchrotron studies thus far. We derive the mass absorption coefficients and the imaginary component of the form factor over this range. We apply conventional XAFS analytic techniques, extended to include error propagation and uncertainty, yielding bond lengths accurate to approximately 0.24% and thermal Debye-Waller parameters accurate to 30%. We then introduce the FDMX technique for accurate analysis of such data across the full XAFS spectrum, built on full-potential theory, yielding a bond length accuracy of order 0.1% and the demonstration that a single Debye parameter is inadequate and inconsistent across the XAFS range. Two effective Debye-Waller parameters are determined: a high-energy value based on the highly-correlated motion of bonded atoms ([Formula: see text] Å), and an uncorrelated bulk value ([Formula: see text] Å) in good agreement with that derived from (room-temperature) crystallography. PMID:26075571

  10. Structure determination from XAFS using high-accuracy measurements of x-ray mass attenuation coefficients of silver, 11 keV–28 keV, and development of an all-energies approach to local dynamical analysis of bond length, revealing variation of effective thermal contributions across the XAFS spectrum

    NASA Astrophysics Data System (ADS)

    Tantau, L. J.; Chantler, C. T.; Bourke, J. D.; Islam, M. T.; Payne, A. T.; Rae, N. A.; Tran, C. Q.

    2015-07-01

    We use the x-ray extended range technique (XERT) to experimentally determine the mass attenuation coefficient of silver in the x-ray energy range 11 kev–28 kev including the silver K absorption edge. The results are accurate to better than 0.1%, permitting critical tests of atomic and solid state theory. This is one of the most accurate demonstrations of cross-platform accuracy in synchrotron studies thus far. We derive the mass absorption coefficients and the imaginary component of the form factor over this range. We apply conventional XAFS analytic techniques, extended to include error propagation and uncertainty, yielding bond lengths accurate to approximately 0.24% and thermal Debye–Waller parameters accurate to 30%. We then introduce the FDMX technique for accurate analysis of such data across the full XAFS spectrum, built on full-potential theory, yielding a bond length accuracy of order 0.1% and the demonstration that a single Debye parameter is inadequate and inconsistent across the XAFS range. Two effective Debye–Waller parameters are determined: a high-energy value based on the highly-correlated motion of bonded atoms ({?\\text{DW}}=0.1413(21) Å), and an uncorrelated bulk value ({?\\text{DW}}=0.1766(9) Å) in good agreement with that derived from (room-temperature) crystallography.

  11. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60keV

    Microsoft Academic Search

    Martin D. de Jonge; Chanh Q. Tran; Christopher T. Chantler; Zwi Barnea; Bipin B. Dhal; David Paterson; Elliot P. Kanter; Stephen H. Southworth; Linda Young; Mark A. Beno; Jennifer A. Linton; Guy Jennings

    2007-01-01

    We use the x-ray extended-range technique (XERT) [C. T. Chantler , Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60keV to 0.04-3% accuracy, and typically in the range 0.1-0.2% . Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and

  12. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60 keV

    Microsoft Academic Search

    Martin D. de Jonge; Chanh Q. Tran; Christopher T. Chantler; Zwi Barnea; Bipin B. Dhal; David Paterson; Elliot P. Kanter; Stephen H. Southworth; Linda Young; Mark A. Beno; Jennifer A. Linton; Guy Jennings

    2007-01-01

    We use the x-ray extended-range technique (XERT) [C. T. Chantler et al., Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60 keV to 0.04-3 % accuracy, and typically in the range 0.1-0.2 %. Measurements made over an extended range of the measurement parameter space are critically examined to

  13. Variations of the Solar Flux in the 1 to 50 nm Range Over a Solar Rotation Inferred From Observations of Photoelectrons With Energies From 0.01 to 1 keV From the FAST Satellite

    Microsoft Academic Search

    W. Peterson; P. Chamberlin; T. Woods; P. Richards

    2006-01-01

    We have analyzed one minute average photoelectron energy spectra from 10 eV to 1 keV observed at ~ 3,000 km, equatorward of the auroral oval for the July-August, 2002 Solar rotation. Variations in these photoelectron spectra arise primarily from variations in the Solar flux in the 1 to 50 nm range and to a lesser extent changes in the composition

  14. Cross Sections and Swarm Coefficients for H + , H2 + , H3 + , H, H2, and H - in H2 for Energies from 0.1 eV to 10 keV

    Microsoft Academic Search

    A. V. Phelps

    1990-01-01

    Graphical and tabulated data and the associated bibliography are presented for cross sections for elastic, excitation and ionization collisions of H+, H2+, H3+, H, H2, and H? with H2 at laboratory energies from 0.1 to 10 keV. Where appropriate, drift velocities and reaction or excitation coefficients are calculated from the cross sections and recommended for use in analyses of swarm

  15. Neutron physics of the Re/Os clock. II. The (n,n{sup '}) cross section of {sup 187}Os at 30 keV neutron energy

    SciTech Connect

    Mosconi, M.; Heil, M.; Kaeppeler, F.; Plag, R.; Mengoni, A. [Karlsruhe Institute of Technology (KIT), Campus Nord, Institut fuer Kernphysik, D-76021 Karlsruhe (Germany); International Atomic Energy Agency, Nuclear Data Section, A-1400 Vienna (Austria)

    2010-07-15

    The inelastic neutron-scattering cross section of {sup 187}Os has been determined in a time-of-flight experiment at the Karlsruhe 3.7-MV Van de Graaff accelerator. An almost monoenergetic beam of 30-keV neutrons was produced at the threshold of the {sup 7}Li(p,n){sup 7}Be reaction. Information on the inelastic channel is required for reliable calculations of the so-called stellar enhancement factor, by which the laboratory cross section of {sup 187}Os must be corrected in order to account for the thermal population of low-lying excited states at the temperatures of s-process nucleosynthesis, in particular of the important state at 9.75 keV. This correction represents a crucial step in the interpretation of the {sup 187}Os/{sup 187}Re pair as a cosmochronometer.

  16. Demonstration of Direct Energy Recovery of Full Energy Ions at 40 keV on a PLT\\/ISX Beam System

    Microsoft Academic Search

    W. L. Stirling; G. C. Barber; W. K. Dagenhart; R. R. Feezell; W. L. Gardner; H. H. Haselton; J. Kim; M. Menon; N. S. Ponte; C. C. Tsai; J. H. Whealton

    1981-01-01

    Neutral beam injection systems that employ positive ion sources presently operate at energies of about 40 to 50 keV\\/nucleon at 60 A (Princeton Large Torus (PLT)) or 100 A (Princeton Divertor Experiment (PDX) or the Oak Ridge National Laboratory (ORNL) Impurities Study Experiment (ISX)) with about 60% conversion efficiency. However, the desire for multisecond beams in the 80-keV\\/nucleon energy range

  17. High-efficiency B?C/Mo?C alternate multilayer grating for monochromators in the photon energy range from 0.7 to 3.4 keV.

    PubMed

    Choueikani, Fadi; Lagarde, Bruno; Delmotte, Franck; Krumrey, Michael; Bridou, Françoise; Thomasset, Muriel; Meltchakov, Evgueni; Polack, François

    2014-04-01

    An alternate multilayer (AML) grating has been prepared by coating an ion etched lamellar grating with a B4C/Mo2C multilayer (ML) having a layer thickness close to the groove depth. Such a structure behaves as a 2D synthetic crystal and can reach very high efficiencies when the Bragg condition is satisfied. This AML coated grating has been characterized at the SOLEIL Metrology and Tests Beamline between 0.7 and 1.7 keV and at the four-crystal monochromator beamline of Physikalisch-Technische Bundesanstalt (PTB) at BESSY II between 1.75 and 3.4 keV. A peak diffraction efficiency of nearly 27% was measured at 2.2 keV. The measured efficiencies are well reproduced by numerical simulations made with the electromagnetic propagation code CARPEM. Such AML gratings, paired with a matched ML mirror, constitute efficient monochromators for intermediate energy photons. They will extend the accessible energy for many applications as x-ray absorption spectroscopy or x-ray magnetic circular dichroism experiments. PMID:24686695

  18. Experimental and MC determination of HPGe detector efficiency in the 40-2754 keV energy range for measuring point source geometry with the source-to-detector distance of 25 cm.

    PubMed

    Dryak, Pavel; Kovar, Petr

    2006-01-01

    A precise model of a 40% relative efficiency p-type HPGe detector was created for photon detection efficiency calculation using the MCNP code. All detector parameters were determined by different experiments. No experimental calibration points were used for the modification of detector parameters. The model was validated by comparing calculated and experimental full energy peak efficiencies in the 40-2754 keV energy range, for point-source geometry with the source-to-detector distance of 25 cm. PMID:16564693

  19. Neutron inelastic scattering cross sections for states above 700 keV in /sup 232/Th

    SciTech Connect

    Ciarcia, C.A.; Couchell, G.P.; Egan, J.J.; Kegel, G.H.R.; Li, S.Q.; Mittler, A.; Pullen, D.J.; Schier, W.A.; Shao, J.Q.

    1985-12-01

    Fast neutron inelastic scattering cross sections for levels between 700- and 1400-keV excitation energy in /sup 232/Th have been measured using the (n,n') time-of-flight (TOF) technique. Measurements of 125-deg differential cross sections were made using neutrons with a typical energy spread of 8 to 10 keV, generated by the /sup 7/Li(p,n)/sup 7/ Be reaction. The incident neutron energies covere three regions: (a) 950 to 1550 keV in 50-keV intervals with the TOF spectrometer optimized to detect 200 to 600-keV scattered neutrons, (b) 1200 to 2000 keV in 100-keV intervals with the spectrometer optimized to detect 400- to 800-keV scattered neutrons, and (c) 1700 to 2100 keV in 100-keV steps with the spectrometer optimized for 800- to 1300-keV scattered neutrons. Throughout the experiment, an overall energy resolution of <15 keV was maintained. Level cross sections were deduced from the 125-deg differential scattering cross sections and are compared with (n,n'..gamma..) measurements and the ENDF/B-V evaluation. Angular distributions for states in the 700- to 900-keV region have been measured at 1.2, 1.5, and 2.0 MeV.

  20. The 1 keV to 200 keV X-ray Spectrum of NGC 2992 and NGC 3081

    E-print Network

    Volker Beckmann; Neil Gehrels; Jack Tueller

    2007-04-20

    The Seyfert 2 galaxies NGC 2992 and NGC 3081 have been observed by INTEGRAL and Swift. We report about the results and the comparison of the spectrum above 10 keV based on INTEGRAL IBIS/ISGRI, Swift/BAT, and BeppoSAX/PDS. A spectrum can be extracted in the X-ray energy band ranging from 1 keV up to 200 keV. Although NGC 2992 shows a complex spectrum below 10 keV, the hard tail observed by various missions exhibits a slope with photon index = 2, independent on the flux level during the observation. No cut-off is detectable up to the detection limit around 200 keV. In addition, NGC 3081 is detected in the INTEGRAL and Swift observation and also shows an unbroken Gamma = 1.8 spectrum up to 150 keV. These two Seyfert galaxies give further evidence that a high-energy cut-off in the hard X-ray spectra is often located at energies E_C >> 100 keV. In NGC 2992 a constant spectral shape is observed over a hard X-ray luminosity variation by a factor of 11. This might indicate that the physical conditions of the emitting hot plasma are constant, while the amount of plasma varies, due to long-term flaring activity.

  1. Dedicated STEM for 200 to 40 keV operation

    Microsoft Academic Search

    N. Dellby; N. J. Bacon; P. Hrncirik; M. F. Murfitt; G. S. Skone; Z. S. Szilagyi; O. L. Krivanek

    2011-01-01

    A dedicated STEM developed for operation at primary energies from 200 keV to 40 keV and lower is described. It has a new cold field emission gun (CFEG) that gives a normalized brightness of 3 × 108 A\\/(m2 sr V), and excellent short-term and long-term stability. It includes two gun lenses (one electrostatic and one electromagnetic), a fast electrostatic beam

  2. A NOVEL APPROACH TO MEASURE THE CROSS SECTION OF THE {sup 18}O(p, alpha){sup 15}N RESONANT REACTION IN THE 0-200 keV ENERGY RANGE

    SciTech Connect

    La Cognata, M.; Spitaleri, C.; Cherubini, S.; Crucilla, V.; Gulino, M.; Lamia, L.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L. [INFN - Laboratori Nazionali del Sud and DMFCI - Universita di Catania, Catania (Italy); Mukhamedzhanov, A.; Banu, A.; Goldberg, V.; Tabacaru, G.; Trache, L. [Cyclotron Institute - Texas A and M University, College Station, TX (United States); Coc, A. [CSNSM CNRS/IN2P3, Universite Paris Sud, Orsay (France); Irgaziev, B. [GIK - Institute of Engineering Sciences and Technology, Topi District, Swabi NWFP (Pakistan); Kiss, G. G. [ATOMKI, Debrecen (Hungary); Mrazek, J., E-mail: Spitaleri@lns.infn.i [Nuclear Physics Institute of ASCR, Rez (Czech Republic)

    2010-01-01

    The {sup 18}O(p, alpha){sup 15}N reaction is of primary importance to pin down the uncertainties, due to nuclear physics input, affecting present-day models of asymptotic giant branch stars. Its reaction rate can modify both fluorine nucleosynthesis inside such stars and oxygen and nitrogen isotopic ratios, which allow one to constrain the proposed astrophysical scenarios. Thus, an indirect measurement of the low-energy region of the {sup 18}O(p, alpha){sup 15}N reaction has been performed to access, for the first time, the range of relevance for astrophysical application. In particular, a full, high-accuracy spectroscopic study of the 20 and 90 keV resonances has been performed and the strengths deduced to evaluate the reaction rate and the consequences for astrophysics.

  3. Particle size effect in CaF2:Mn\\/Teflon TLD response at photon energies from 5-1250 keV

    Microsoft Academic Search

    G. A. Carlson; L. Lorence; D. W. Vehar; R. S. Klingler

    1990-01-01

    Thermoluminescent dosimeters (TDLs) fabricated by embedding CaF 2:Mn powder in a Teflon matrix (TTLDs) are sometimes used to monitor dose in silicon-device radiation effects experiments. A potential advantage of TTLDs over other types of TLDs for this application is that their weighted-average mass energy-absorption coefficient is near that of Si. Experimental results are presented which demonstrate that for moderate-energy X-rays,

  4. OSLD energy response performance and dose accuracy at 24 - 1250 keV: Comparison with TLD-100H and TLD-100

    SciTech Connect

    Kadir, A. B. A. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi, Malaysia and Secondary Standard Dosimetry Laboratory (SSDL), Malaysia Nuclear Agency, Bangi, 43000 Kajang (Malaysia); Priharti, W.; Samat, S. B. [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 UKM Bangi (Malaysia); Dolah, M. T. [Secondary Standard Dosimetry Laboratory (SSDL), Malaysia Nuclear Agency, Bangi, 43000 Kajang (Malaysia)

    2013-11-27

    OSLD was evaluated in terms of energy response and accuracy of the measured dose in comparison with TLD-100H and TLD-100. The OSLD showed a better energy response performance for H{sub p}(10) whereas for H{sub p}(0.07), TLD-100H is superior than the others. The OSLD dose accuracy is comparable with the other two dosimeters since it fulfilled the requirement of the ICRP trumpet graph analysis.

  5. OSLD energy response performance and dose accuracy at 24 - 1250 keV: Comparison with TLD-100H and TLD-100

    NASA Astrophysics Data System (ADS)

    Kadir, A. B. A.; Priharti, W.; Samat, S. B.; Dolah, M. T.

    2013-11-01

    OSLD was evaluated in terms of energy response and accuracy of the measured dose in comparison with TLD-100H and TLD-100. The OSLD showed a better energy response performance for Hp(10) whereas for Hp(0.07), TLD-100H is superior than the others. The OSLD dose accuracy is comparable with the other two dosimeters since it fulfilled the requirement of the ICRP trumpet graph analysis.

  6. Experimental study of interactions of highly charged ions with atoms at keV energies. Progress report, August 15, 1990--February 15, 1993

    SciTech Connect

    Kostroun, V.O.

    1993-01-29

    This final progress report summarizes the work carried out during the 29 month period from August 15, 1990 to February 15, 1993 under grant DE-FG02-86ER13519. The following experiments were done. We measured the absolute total and one- and two- electron transfer cross sections for Ar{sup q+} (8{le} q {le} 16) on He and H{sub 2} at 2.3 qkeV, the angular distributions of the scattered projectiles in Ar{sup 8+,9+} collisions, with Ar and Kr at 2.3 qkeV, the electron emissions in low energy Ar{sup q+} on Ar collisions, the recoil ion charge state distributions in low energy Ar{sup q+} -Ar collisions, the absolute total and one-and two-electron transfer cross sections for Ar{sup 8+} on Ar at 2.3 qkeV, and the absolute total and one- and two-electron transfer cross sections for Ar{sup 8+} on Ar as a function of energy. We also used energy gain spectroscopy to study Ar{sup q+} on Ar collisions at 40 and 30 qeV, and time of flight spectroscopy to investigate ionization and dissociation of CO and N{sub 2} in collisions with low energy, highly charged argon ions. In addition, we applied the Goldberger and Watson transition theory to derive transition rates and cross sections for atomic radiative and/or non radiative processes, wrote a computer code TRANSIT which can calculate energies, wave functions and radiative and non radiative rates for atoms and ions. The code is highly modular and can easily be modified to calculate higher order processes. Finally, we have done an Ab-Initio molecular orbital electronic energy level calculation for the (ArAr){sup 8+} system as a function internuclear separation.

  7. Experimental study of interactions of highly charged ions with atoms at keV energies: Progress report for period May 15, 1985February 15, 1987

    Microsoft Academic Search

    Kostroun

    1987-01-01

    Interest in interactions of low energy highly charged ions with electrons, atoms or ions is due to their importance to controlled thermonuclear fusion research and the interesting nature of the fundamental processes involved. Studies of such interactions have long been hampered by a lack of suitable ions sources. A superconducting solenoid, cryogenic Electron Beam Ion Source, CEBIS, has been constructed

  8. Comparison of GATE\\/GEANT4 with EGSnrc and MCNP for electron dose calculations at energies between 15 keV and 20 MeV

    Microsoft Academic Search

    L. Maigne; Y. Perrot; D. R. Schaart; D. Donnarieix; V. Breton

    2011-01-01

    The GATE Monte Carlo simulation platform based on the GEANT4 toolkit has come into widespread use for simulating positron emission tomography (PET) and single photon emission computed tomography (SPECT) imaging devices. Here, we explore its use for calculating electron dose distributions in water. Mono-energetic electron dose point kernels and pencil beam kernels in water are calculated for different energies between

  9. Analysis of temperature-dependent neutron transmission and self-indication measurements on tantalum at 2-keV neutron energy

    NASA Technical Reports Server (NTRS)

    Semler, T. T.

    1973-01-01

    The method of pseudo-resonance cross sections is used to analyze published temperature-dependent neutron transmission and self-indication measurements on tantalum in the unresolved region. In the energy region analyzed, 1825.0 to 2017.0 eV, a direct application of the pseudo-resonance approach using a customary average strength function will not provide effective cross sections which fit the measured cross section behavior. Rather a local value of the strength function is required, and a set of resonances which model the measured behavior of the effective cross sections is derived. This derived set of resonance parameters adequately represents the observed resonance hehavior in this local energy region. Similar analyses for the measurements in other unresolved energy regions are necessary to obtain local resonance parameters for improved reactor calculations. This study suggests that Doppler coefficients calculated by sampling from grand average statistical distributions over the entire unresolved resonance region can be in error, since significant local variations in the statistical distributions are not taken into consideration.

  10. Systematic survey of the dose enhancement in tissue-equivalent materials facing medium- and high-Z backscatterers exposed to X-rays with energies from 5 to 250 keV.

    PubMed

    Seidenbusch, M; Harder, D; Regulla, D

    2014-05-01

    The present study has been inspired by the results of earlier dose measurements in tissue-equivalent materials adjacent to thin foils of aluminum, copper, tin, gold, and lead. Large dose enhancements have been observed in low-Z materials near the interface when this ensemble was irradiated with X-rays of qualities known from diagnostic radiology. The excess doses have been attributed to photo-, Compton, and Auger electrons released from the metal surfaces. Correspondingly, high enhancements of biological effects have been observed in single cell layers arranged close to gold surfaces. The objective of the present work is to systematically survey, by calculation, the values of the dose enhancement in low-Z media facing backscattering materials with a variety of atomic numbers and over a large range of photon energies. Further parameters to be varied are the distance of the point of interest from the interface and the kind of the low-Z material. The voluminous calculations have been performed using the PHOTCOEF algorithm, a proven set of interpolation functions fitted to long-established Monte Carlo results, for primary photon energies between 5 and 250 keV and for atomic numbers varying over the periodic system up to Z = 100. The calculated results correlate well with our previous experimental results. It is shown that the values of the dose enhancement (a) vary strongly in dependence upon Z and photon energy; (b) have maxima in the energy region from 40 to 60 keV, determined by the K and L edges of the backscattering materials; and (c) are valued up to about 130 for "International Commission on Radiological Protection (ICRP) soft tissue" (soft tissue composition recommended by the ICRP) as the adjacent low-Z material. Maximum dose enhancement associated with the L edge occurs for materials with atomic numbers between 50 and 60, e.g., barium (Z = 56) and iodine (Z = 53). Such materials typically serve as contrast media in medical X-ray diagnostics. The gradual reduction in the dose enhancement with increasing distance from the material interface, owed to the limited ranges of the emitted secondary electrons, has been documented in detail. The discussion is devoted to practical radiological aspects of the dose enhancement phenomenon. Cytogenetic effects in cell layers closely proximate to surfaces of medium-Z materials might vary over two orders of magnitude, because the dose enhancement is accompanied by the earlier observed about twofold increase in the low-dose RBEM at a tissue-to-gold interface. PMID:24633421

  11. R-matrix analysis of {sup 235}U neutron transmission and cross sections in the energy range 0 to 2.25 keV

    SciTech Connect

    Leal, L.C.; Derrien, H.; Larson, N.M.; Wright, R.Q.

    1997-11-01

    This document describes a new R-matrix analysis of {sup 235}U cross section data in the energy range from 0 to 2,250 eV. The analysis was performed with the computer code SAMMY, that has recently been updated to permit, for the first time, inclusion of both differential and integral data within the analysis process. Fourteen differential data sets and six integral quantities were used in this evaluation: two measurements of fission plus capture, one of fission plus absorption, six of fission alone, two of transmission, and one of eta, plus standard values of thermal cross sections for fission, capture, and scattering, and of K1 and the Westcott g-factors for both fission and absorption. An excellent representation was obtained for the high-resolution transmission, fission, and capture cross-section data as well as for the integral quantities. The result is a single set of resonance parameters spanning the entire range up to 2,250 eV, a decided improvement over the present ENDF/VI evaluation, in which eleven discrete resonance parameter sets are required to cover that same energy range. This new evaluation is expected to greatly improve predictability of the criticality safety margins for nuclear systems in which {sup 235}U is present.

  12. High resolution measurement of the /sup 238/U neutron capture yield for incident neutron energies between 1 and 100 keV

    SciTech Connect

    Macklin, R.L.; Perez, R.B.; de Saussure, G.; Ingle, R.W.

    1987-01-01

    Measurements of the capture gamma-ray spectrum of three U-238 metallic samples of areal densities, N = 0.0124, 0.0031, and 0.00057 at/b, were performed by placing a sample at the center of the Oak Ridge Electron Linear Accelerator liquid scintillator tank. Five measurements of the time of flight spectrum were performed for each sample thickness. Measurements were done with and without aluminum filters in the beam, at both 800 and 400 pulses per second to determine the energy-dependent background which arises from pulse overlap and room return. The fifth measurement had a polyethylene plug in the beam to determine the constant background due to cosmic rays and long-lived radioactivities in the sample and surrounding materials. The shape of the incident neutron spectrum was determined by the count rate of a 1-mm-thick Li-6 glass scintillation monitor placed upstream of the liquid scintillator. (DWL)

  13. Fermi Observations of GRB 090510: A Short Hard Gamma-Ray Burst with an Additional, Hard Power-Law Component from 10 keV to GeV Energies

    E-print Network

    LAT, The Fermi

    2010-01-01

    We present detailed observations of the bright short-hard gamma-ray burst GRB 090510 made with the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi observatory. GRB 090510 is the first burst detected by the LAT that shows strong evidence for a deviation from a Band spectral fitting function during the prompt emission phase. The time-integrated spectrum is fit by the sum of a Band function with $\\Epeak = 3.9\\pm 0.3$\\,MeV, which is the highest yet measured, and a hard power-law component with photon index $-1.62\\pm 0.03$ that dominates the emission below $\\approx$\\,20\\,keV and above $\\approx$\\,100\\,MeV. The onset of the high-energy spectral component appears to be delayed by $\\sim$\\,0.1\\,s with respect to the onset of a component well fit with a single Band function. A faint GBM pulse and a LAT photon are detected 0.5\\,s before the main pulse. During the prompt phase, the LAT detected a photon with energy $30.5^{+5.8}_{-2.6}$ GeV, the highest ever measured from a short GRB. Observ...

  14. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of molybdenum over the 13.5-41.5-keV energy range

    NASA Astrophysics Data System (ADS)

    de Jonge, Martin D.; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi; Dhal, Bipin B.; Cookson, David J.; Lee, Wah-Keat; Mashayekhi, Ali

    2005-03-01

    We use the x-ray extended-range technique (XERT) [Chantler , Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of molybdenum in the x-ray energy range of 13.5-41.5keV to 0.02-0.15 % accuracy. Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and correct where necessary a number of experimental systematic errors. These results represent the most extensive experimental data set for molybdenum and include absolute mass attenuation coefficients in the regions of the x-ray absorption fine structure (XAFS) and x-ray-absorption near-edge structure (XANES). The imaginary component of the atomic form-factor f2 is derived from the photoelectric absorption after subtracting calculated Rayleigh and Compton scattering cross sections from the total attenuation. Comparison of the result with tabulations of calculated photoelectric absorption coefficients indicates that differences of 1-15 % persist between the calculated and observed values.

  15. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60keV

    NASA Astrophysics Data System (ADS)

    de Jonge, Martin D.; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi; Dhal, Bipin B.; Paterson, David; Kanter, Elliot P.; Southworth, Stephen H.; Young, Linda; Beno, Mark A.; Linton, Jennifer A.; Jennings, Guy

    2007-03-01

    We use the x-ray extended-range technique (XERT) [C. T. Chantler , Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60keV to 0.04-3% accuracy, and typically in the range 0.1-0.2% . Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and correct a number of potential experimental systematic errors. These results represent the most extensive experimental data set for tin and include absolute mass attenuation coefficients in the regions of x-ray absorption fine structure, extended x-ray absorption fine structure, and x-ray absorption near-edge structure. The imaginary component of the atomic form factor f2 is derived from the photoelectric absorption after subtracting calculated Rayleigh and Compton scattering cross sections from the total attenuation. Comparison of the result with tabulations of calculated photoelectric absorption coefficients indicates that differences of 1-2% persist between calculated and observed values.

  16. Dynamics of fluxes of protons with energies 30-80 keV during geomagnetic storms on January 21-22, 2005, and December 14-15, 2006, according to data from low-orbit satellites

    NASA Astrophysics Data System (ADS)

    Vlasova, N. A.; Kalegaev, V. V.

    2014-11-01

    We present the results of a comparative analysis of the dynamics of three populations of fluxes of protons with energy 30-80 keV as measured by NOAA solar-synchronous satellites ( POES 15, 16, 17) at low latitudes ( L < 2) and at latitudes lower and higher than the boundary of isotropic precipitation during the geomagnetic storms on January 21-22, 2005 and December 14-15, 2006. Based on a complex analysis of experimental data on particle fluxes at low orbits and on measurements of solar wind parameters performed by the ACE spacecraft, we have studied the dynamical peculiarities of the fluxes of particles and of their longitudinal distributions depending on the conditions in the interplanetary medium. It is shown that an increase of trapped particle fluxes and the development of the main phase of the geomagnetic storm on January 21-22, 2005 are associated with the magnetosphere's response to a prolonged action of an extremely powerful coronal mass ejection at a northern orientation of the IMF. On December 14, 2006 an insufficient amplitude and duration of the pressure impulse did not result in development of a disturbance similar to January 21-22, 2005. The development of the main phase of this storm is related to a southward turn of the IMF, which has occurred only seven hours after the SSC.

  17. Measurement of the x-ray mass attenuation coefficient and determination of the imaginary component of the atomic form factor of tin over the energy range of 29-60 keV

    SciTech Connect

    Jonge, Martin D. de; Tran, Chanh Q.; Chantler, Christopher T.; Barnea, Zwi; Dhal, Bipin B.; Paterson, David; Kanter, Elliot P.; Southworth, Stephen H.; Young, Linda; Beno, Mark A.; Linton, Jennifer A.; Jennings, Guy [X-Ray Operations and Research, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); School of Physics, University of Melbourne, Victoria 3010 (Australia); Australian Synchrotron Project, Major Projects Victoria, 800 Blackburn Road, Clayton, Victoria 3168 (Australia); Chemistry Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); BESSRC-CAT, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2007-03-15

    We use the x-ray extended-range technique (XERT) [C. T. Chantler et al., Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of tin in the x-ray energy range of 29-60 keV to 0.04-3 % accuracy, and typically in the range 0.1-0.2 %. Measurements made over an extended range of the measurement parameter space are critically examined to identify, quantify, and correct a number of potential experimental systematic errors. These results represent the most extensive experimental data set for tin and include absolute mass attenuation coefficients in the regions of x-ray absorption fine structure, extended x-ray absorption fine structure, and x-ray absorption near-edge structure. The imaginary component of the atomic form factor f{sub 2} is derived from the photoelectric absorption after subtracting calculated Rayleigh and Compton scattering cross sections from the total attenuation. Comparison of the result with tabulations of calculated photoelectric absorption coefficients indicates that differences of 1-2 % persist between calculated and observed values.

  18. Fermi Observations of GRB 090510: A Short-Hard Gamma-ray Burst with an Additional, Hard Power-law Component from 10 keV TO GeV Energies

    NASA Astrophysics Data System (ADS)

    Ackermann, M.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Ballet, J.; Barbiellini, G.; Baring, M. G.; Bastieri, D.; Bechtol, K.; Bellazzini, R.; Berenji, B.; Bhat, P. N.; Bissaldi, E.; Blandford, R. D.; Bloom, E. D.; Bonamente, E.; Borgland, A. W.; Bouvier, A.; Bregeon, J.; Brez, A.; Briggs, M. S.; Brigida, M.; Bruel, P.; Buson, S.; Caliandro, G. A.; Cameron, R. A.; Caraveo, P. A.; Carrigan, S.; Casandjian, J. M.; Cecchi, C.; Çelik, Ö.; Charles, E.; Chiang, J.; Ciprini, S.; Claus, R.; Cohen-Tanugi, J.; Connaughton, V.; Conrad, J.; Dermer, C. D.; de Palma, F.; Dingus, B. L.; Silva, E. do Couto e.; Drell, P. S.; Dubois, R.; Dumora, D.; Farnier, C.; Favuzzi, C.; Fegan, S. J.; Finke, J.; Focke, W. B.; Frailis, M.; Fukazawa, Y.; Fusco, P.; Gargano, F.; Gasparrini, D.; Gehrels, N.; Germani, S.; Giglietto, N.; Giordano, F.; Glanzman, T.; Godfrey, G.; Granot, J.; Grenier, I. A.; Grondin, M.-H.; Grove, J. E.; Guiriec, S.; Hadasch, D.; Harding, A. K.; Hays, E.; Horan, D.; Hughes, R. E.; Jóhannesson, G.; Johnson, W. N.; Kamae, T.; Katagiri, H.; Kataoka, J.; Kawai, N.; Kippen, R. M.; Knödlseder, J.; Kocevski, D.; Kouveliotou, C.; Kuss, M.; Lande, J.; Latronico, L.; Lemoine-Goumard, M.; Llena Garde, M.; Longo, F.; Loparco, F.; Lott, B.; Lovellette, M. N.; Lubrano, P.; Makeev, A.; Mazziotta, M. N.; McEnery, J. E.; McGlynn, S.; Meegan, C.; Mészáros, P.; Michelson, P. F.; Mitthumsiri, W.; Mizuno, T.; Moiseev, A. A.; Monte, C.; Monzani, M. E.; Moretti, E.; Morselli, A.; Moskalenko, I. V.; Murgia, S.; Nakajima, H.; Nakamori, T.; Nolan, P. L.; Norris, J. P.; Nuss, E.; Ohno, M.; Ohsugi, T.; Omodei, N.; Orlando, E.; Ormes, J. F.; Ozaki, M.; Paciesas, W. S.; Paneque, D.; Panetta, J. H.; Parent, D.; Pelassa, V.; Pepe, M.; Pesce-Rollins, M.; Piron, F.; Preece, R.; Rainò, S.; Rando, R.; Razzano, M.; Razzaque, S.; Reimer, A.; Ritz, S.; Rodriguez, A. Y.; Roth, M.; Ryde, F.; Sadrozinski, H. F.-W.; Sander, A.; Scargle, J. D.; Schalk, T. L.; Sgrò, C.; Siskind, E. J.; Smith, P. D.; Spandre, G.; Spinelli, P.; Stamatikos, M.; Stecker, F. W.; Strickman, M. S.; Suson, D. J.; Tajima, H.; Takahashi, H.; Takahashi, T.; Tanaka, T.; Thayer, J. B.; Thayer, J. G.; Thompson, D. J.; Tibaldo, L.; Toma, K.; Torres, D. F.; Tosti, G.; Tramacere, A.; Uchiyama, Y.; Uehara, T.; Usher, T. L.; van der Horst, A. J.; Vasileiou, V.; Vilchez, N.; Vitale, V.; von Kienlin, A.; Waite, A. P.; Wang, P.; Wilson-Hodge, C.; Winer, B. L.; Wu, X. F.; Yamazaki, R.; Yang, Z.; Ylinen, T.; Ziegler, M.

    2010-06-01

    We present detailed observations of the bright short-hard gamma-ray burst GRB 090510 made with the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) on board the Fermi observatory. GRB 090510 is the first burst detected by the LAT that shows strong evidence for a deviation from a Band spectral fitting function during the prompt emission phase. The time-integrated spectrum is fit by the sum of a Band function with E peak = 3.9 ± 0.3 MeV, which is the highest yet measured, and a hard power-law component with photon index -1.62 ± 0.03 that dominates the emission below ?20 keV and above ?100 MeV. The onset of the high-energy spectral component appears to be delayed by ~0.1 s with respect to the onset of a component well fit with a single Band function. A faint GBM pulse and a LAT photon are detected 0.5 s before the main pulse. During the prompt phase, the LAT detected a photon with energy 30.5+5.8 -2.6 GeV, the highest ever measured from a short GRB. Observation of this photon sets a minimum bulk outflow Lorentz factor, ?gsim 1200, using simple ?? opacity arguments for this GRB at redshift z = 0.903 and a variability timescale on the order of tens of ms for the ?100 keV-few MeV flux. Stricter high confidence estimates imply ? >~ 1000 and still require that the outflows powering short GRBs are at least as highly relativistic as those of long-duration GRBs. Implications of the temporal behavior and power-law shape of the additional component on synchrotron/synchrotron self-Compton, external-shock synchrotron, and hadronic models are considered.

  19. Detection of interplanetary electrons from 18 keV to 1.8 MeV during solar quiet times, 1. On the origin of 200 KeV interplanetary electrons, 2.

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Cline, T. L.; Ramaty, R.; Fisk, L. A.

    1972-01-01

    A quiet time component of interplanetary electrons having energies above solar wind energies and below those characterized as cosmic radiation was observed. Its energy spectrum falls with energy from 18 keV to 1.8 MeV, but it shows a feature in the 100 to 300 keV range. The observed temporal variations of the intensity suggest that the 18 to 100 keV portion is solar and the 0.3 to 1.8 MeV portion is galactic in origin. Solar and terrestrial neutron decay electrons appear inadequate to explain the 100 to 300 keV feature.

  20. K+ charge transfer in H2 at low keV collisions

    NASA Astrophysics Data System (ADS)

    Alarcón, F. B.; Martinez, H.; Fuentes, B. E.; Yousif, F. B.

    2013-08-01

    Absolute electron capture cross sections for the K+-H2 pair, employing beam collision spectroscopy for 0.4-4 keV energy were measured. The capture cross section increased with the increase in collision energy. The results below 2 keV overlap with previously measured data of other investigators and extend down in energy to 400 eV, where no previous data have been reported. Experimental data were compared with calculations employing the Olson model, which were found to agree in behavior as well as with an absolute value above 100 keV.

  1. High angular resolution cosmic X-ray astronomy observations in the energy range 0.15-2 keV and XUV observations of nearby stars from an attitude controlled rocket

    NASA Technical Reports Server (NTRS)

    Garmire, G. P.

    1974-01-01

    The construction of a two dimensional focusing Wolter Type I mirror system for X-ray and XUV astronomical observations from an Astrobee F sounding rocket is described. The mirror design goal will have a one degree field, a 20-arc seconds resolution, an effective area of about 50 sq cm at 1 keV and 10 sq cm at 0.25 keV on axis. A star camera provides aspect data to about 15-arc seconds. Two detectors are placed at the focus with an interchange mechanism to allow a detector change during flight. The following specific developments are reported: (1) position sensitive proportional counter development; (2) channel plate multiplier development; (3) telescope mirror development and payload structure; (4) Australian rocket flight results; (5) Comet Kohoutek He I observation; and (6) Vela, Puppis A, and Gem-Mon bright patch observations.

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

    Microsoft Academic Search

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

    2004-01-01

    The K–L and K–M resonant Raman scattering (RRS) cross-sections have been measured for the first time at the 59.536 keV photon energy in the 70Yb (BK=61.332 keV), 71Lu (BK=63.316 keV) and 72Hf (BK=65.345 keV) elements; BK being the K-shell binding energy. The K–L and K–M RRS measurements have been performed at the 59° and 133° angles, respectively, to avoid interference

  3. Rayleigh scattering of 145- and 279keV gamma rays in Al, Cu, Sn, and Pb at forward angles

    Microsoft Academic Search

    Mari Gowda; S. J. Anasuya; K. S. Puttaswamy

    1986-01-01

    The integral Rayleigh scattering (RS) cross sections of gamma rays for Al, Cu, and Sn at 145 keV energy and for Al, Cu, Sn, and Pb at 279 keV energy have been determined at angles below 7° by a new method, and are compared with the theoretical integral RS cross sections computed using the non- relativistic form factors (NRFF) of

  4. A keV string axion from high scale supersymmetry

    NASA Astrophysics Data System (ADS)

    Henning, Brian; Kehayias, John; Murayama, Hitoshi; Pinner, David; Yanagida, Tsutomu T.

    2015-02-01

    Various theoretical and experimental considerations motivate models with high-scale supersymmetry breaking. While such models may be difficult to test in colliders, we propose looking for signatures at much lower energies. We show that a keV line in the x-ray spectrum of galaxy clusters (such as the recently disputed 3.5-keV observation) can have its origin in a universal string axion coupled to a hidden supersymmetry breaking sector. A linear combination of the string axion and an additional axion in the hidden sector remains light, obtaining a mass of order 10 keV through supersymmetry breaking dynamics. In order to explain the x-ray line, the scale of supersymmetry breaking must be about 1 011 - 12 GeV . This motivates high-scale supersymmetry as in pure gravity mediation or minimal split supersymmetry and is consistent with all current limits. Since the axion mass is controlled by a dynamical mass scale, this mass can be much higher during inflation, avoiding isocurvature (and domain wall) problems associated with high-scale inflation. In an appendix, we present a mechanism for dilaton stabilization that additionally leads to O (1 ) modifications of the gaugino mass from anomaly mediation.

  5. Ultrafast 25 keV backlighting for experiments on Z.

    SciTech Connect

    Sefkow, Adam B.; Atherton, Briggs W.; Geissel, Matthias; Schollmeier, Marius; Pitts, Todd Alan; Rambo, Patrick K.; Schwarz, Jens; Kimmel, Mark W.

    2010-11-01

    To extend the backlighting capabilities for Sandia's Z-Accelerator, Z-Petawatt, a laser which can provide laser pulses of 500 fs length and up to 120 J (100TW target area) or up to 450 J (Z / Petawatt target area) has been built over the last years. The main mission of this facility focuses on the generation of high energy X-rays, such as tin Ka at 25 keV in ultra-short bursts. Achieving 25 keV radiographs with decent resolution and contrast required addressing multiple problems such as blocking of hot electrons, minimization of the source, development of suitable filters, and optimization of laser intensity. Due to the violent environment inside of Z, an additional very challenging task is finding massive debris and radiation protection measures without losing the functionality of the backlighting system. We will present the first experiments on 25 keV backlighting including an analysis of image quality and X-ray efficiency.

  6. Storage of keV ion beams

    SciTech Connect

    Zajfman, Daniel; Bhushan, Kris G. [Department of Particle Physics, Weizmann Institute of Science, Rehovot, 76100 (Israel); Heber, Oded; Rappaport, Michael [Physics Services, Weizmann Institute of Science, Rehovot, 76100 (Israel)

    1999-01-15

    A new ion trap for storing fast (keV) ion beams is presented. The trap, which is electrostatic, stores the ions between two electrostatic mirrors. Two different examples of utilization of the trap are given. The first one required the extraction of the trapped particles after storage, in order to study their collision with an external target, while the second example measured the lifetime of the metastable He{sup -} levels. The advantage of storage using pure electrostatic fields is discussed.

  7. Linac4 45 keV Proton Beam Measurements

    E-print Network

    Bellodi, G; Hein, L M; Lallement, J-B; Lombardi, A M; Midttun, O; Scrivens, R; Posocco, P A

    2013-01-01

    Linac4 is a 160 MeV normal-conducting H- linear accelerator, which will replace the 50 MeV proton Linac2 as injector for the CERN proton complex. Commissioning of the low energy part - comprising the H - source, a 45 keV Low Energy Beam Transport line (LEBT), a 3 MeV Radiofrequency Quadrupole (RFQ) and a Medium Energy Beam Transport (MEBT) - will start in fall 2012 on a dedicated test stand installation. In preparation to this, preliminary measurements were taken using a 45 keV proton source and a temporary LEBT setup, with the aim of characterising the output beam by comparison with the predictions of simulations. At the same time this allowed a first verification of the functionalities of diagnostics instrumentation and acquisition software tools. Measurements of beam profile, emittance and intensity were taken in three different setups: right after the source, after the first and after the second LEBT solenoids respectively. Particle distributions were reconstructed from emittance scan...

  8. INTEGRAL/IBIS Hard X-ray Galactic survey above 100 keV

    NASA Astrophysics Data System (ADS)

    Krivonos, Roman; Revnivtsev, Mikhail; Lutovinov, Alexander; Tsygankov, Sergey

    INTEGRAL observatory has established itself as very successful mission in surveying hard X-ray sky at energies above 20 keV. The sky census at these energies mainly comprises well known accreting-powered compact objects. It is expected that at energies above 100 keV thermal emission processes should be gradually replaced by emission from non thermal particles. This transition region is still largely unexplored despite its potential importance. We present 10-year survey of the sky at energies above 100 keV which is based on substantial extension in exposure with respect to previous INTEGRAL hard X-ray surveys at these energies. We present catalog of detected sources, their statistics and spectral properties.

  9. Energetic electrons, 50 keV 6 MeV, at geosynchronous orbit: their responses to solar wind variations

    E-print Network

    Li, Xinlin

    1 Energetic electrons, 50 keV ­ 6 MeV, at geosynchronous orbit: their responses to solar wind of the upstream solar wind and of energetic electrons at geosynchronous orbit, we analyze the response of electrons over a wide energy range, 50 keV - 6 MeV, to solar wind variations. Enhancements of energetic

  10. Electron bremsstrahlung angular-distribution fits for atomic numbers 1 less than or equal to Z less than or equal to 92, and incident-electron energies 1 keV less than or equal to T less than or equal to 500 keV

    SciTech Connect

    Kissel, L.

    1982-01-01

    The analytic fit of a simple expression to the electron bremsstrahlung angular distribution cross section d/sup 2/sigma/dkd..cap omega.. (differential in the emitted photon energy k and angle ..cap omega..) is investigated. Optimal choices for the fit parameters are determined and fit coefficients are tabulated for a large number of neutral-atom cases. Results are also presented for fits to the relativistic Coulomb-Born approximation. Comparisons between the screened neutral-atom results and the Coulomb-Born results are made. Discrepancies reported to exist between angular distribution cross sections and fit coefficients published by Tseng, Pratt and Lee are confirmed and understood in terms of their choice of fit weight function.

  11. Checking Potassium origin of new emission line at 3.5 keV with K XIX line complex at 3.7 keV

    E-print Network

    Iakubovskyi, Dmytro

    2015-01-01

    Whether the new line at ~3.5 keV, recently detected in different samples of galaxy clusters, Andromeda galaxy and central part of our Galaxy, is due to Potassium emission lines, is now unclear. By using the latest astrophysical atomic emission line database AtomDB v. 3.0.2, we show that the most prospective method to directly check its Potassium origin will be the study of K XIX emission line complex at ~3.7 keV with future X-ray imaging spectrometers such as Soft X-ray spectometer on-board Astro-H mission or microcalorimeter on-board Micro-X sounding rocket experiment. To further reduce the remaining (factor ~3-5) uncertainty of the 3.7/3.5 keV ratio one should perform more precise modeling including removal of significant spatial inhomogeneities, detailed treatment of background components, and further extension of the modeled energy range.

  12. Hyper-filter-fluorescer spectrometer for x-rays above 120 keV

    DOEpatents

    Wang, Ching L. (Livermore, CA)

    1983-01-01

    An apparatus utilizing filter-fluorescer combinations is provided to measure short bursts of high fluence x-rays above 120 keV energy, where there are no practical absorption edges available for conventional filter-fluorescer techniques. The absorption edge of the prefilter is chosen to be less than that of the fluorescer, i.e., E.sub.PRF E.sub.F. In this way, the response function is virtually zero between E.sub.PRF and E.sub.F and well defined and enhanced in an energy band of less than 1000 keV above the 120 keV energy.

  13. Solar Wind ~20-300 keV Superhalo Electrons

    NASA Astrophysics Data System (ADS)

    Wang, L.; Yang, L.; He, J.; Tu, C. Y.; Pei, Z.

    2014-12-01

    High-energy superhalo electrons are present in the interplanetary medium even in absence of any solar activity, carrying important information on the electron acceleration in the solar wind. We present a statistical survey of ~20-300 keV superhalo electrons measured at 1 AU by the WIND 3DP instrument during quiet-time periods from 1995 January through 2013 December. The velocity distribution function of the observed quiet-time superhalo electrons generally fits to a power-law spectrum, f ~ v-?, with ? ranging from ~4 to ~10. The integrated density of these superhalo electrons at 20-300 keV, nsup, ranges from 10?9 cm?3 to 10?5 cm?3. Both log(nsup) and ? show a good correlation with the sunspot number, with larger density and softer spectrum (?~ 6-8) at solar maximum, and smaller density and harder spectrum (?~ 4-5) at solar minimum. The observed power-law spectrum also has no clear association with flares, CMEs, active regions and solar wind core populations, while it shows a weak (~0.3) correlation with in situ solar wind turbulence spectrum. These results suggest that the seed particles of quiet-time superhalo electrons could originate from the Sun, and their acceleration could mainly occur in the interplanetary medium, probably by the electron interaction with solar wind turbulence, or by acceleration at the CIRs.

  14. Tomographic scanning microscope for 1-4 KeV x-rays

    SciTech Connect

    McNulty, I.; Feng, Y.P. [Argonne National Lab., IL (United States); Hadda, W.S.; Trebes, J.E. [Lawrence Livermore National Lab., CA (United States)

    1995-12-31

    X-ray microtomography enables three-dimensional imaging at submicron resolution with elemental and chemical state contrast. The 1-4 KeV energy region is promising for microtomography of biological, microelectronics, and materials sciences specimens. To capitalize on this potential, we are constructing a tomographic scanning x-ray microscope for 1-4 KeV x-ray on a spherical grating monochromator beamline at the Advance Photon Source. The microscope, which uses zone plate optics, has an anticipated spatial resolution of 100 nm and an energy resolution of better than 1 eV.

  15. Observations of gamma-ray burst spectra between 5 keV and 100 MeV

    NASA Astrophysics Data System (ADS)

    Barat, C.

    1993-01-01

    The Franco-Soviet Lilas, Apex (Phobos mission), and Phebus (Granat satellite) experiments allow spectral observations of cosmic gamma-ray bursts over a very broad energy range from 5 keV up to 100 MeV. We present here typical results on continuum shapes, multiple absorption dips at low-energy (less than 100 keV), emission features around 500 keV, and spectral breaks at about 1 MeV. These observations are discussed in the framework of a highly-mgnetized emission source.

  16. Detection of interplanetary electrons from 18 keV to 1.8 MeV during solar quiet times.

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Anderson, K. A.; Cline, T. L.

    1972-01-01

    Observation of a quiet-time component of interplanetary electrons having energies above solar-wind energies and below those characterized as cosmic radiation. The energy spectrum of this component generally falls with energy from 18 keV to 1.8 MeV, but shows a feature in the 100 to 300-keV range. The observed temporal variations of the intensity suggest that the 18 to 100-keV portion is solar and that the 0.3 to 1.8-MeV portion is galactic in origin. Solar and terrestrial neutron-decay electrons appear inadequate to explain the 100 to 300-keV feature.

  17. The Morphology of the X-ray Emission above 2 keV from Jupiter's Aurorae

    NASA Technical Reports Server (NTRS)

    Elsner, R.; Branduardi-Raymont, G.; Galand, M.; Grodent, D.; Waite, J. H.; Cravens, T.; Ford, P.

    2007-01-01

    The discovery in XMM-Newton X-ray data of X-ray emission above 2 keV from Jupiter's aurorae has led us to reexamine the Chandra ACIS-S observations taken in Feb 2003. Chandra's superior spatial resolution has revealed that the auroral X-rays with E > 2 keV are emitted from the periphery of the region emitting those with E < 1 keV. We are presently exploring the relationship of this morphology to that of the FUV emission from the main auroral oval and the polar cap. The low energy emission has previously been established as due to charge exchange between energetic precipitating ions of oxygen and either sulfur or carbon. It seems likely to us that the higher energy emission is due to precipitation of energetic electrons, possibly the same population of electrons responsible for the FUV emission. We discuss our analysis and interpretation.

  18. The solar wind charge-transfer X-ray emission in the 1/4 keV energy range: inferences on Local Bubble hot gas at low Z

    E-print Network

    D. Koutroumpa; R. Lallement; J. C. Raymond; V. Kharchenko

    2008-12-19

    We present calculations of the heliospheric SWCX emission spectra and their contributions in the ROSAT 1/4 keV band. We compare our results with the soft X-ray diffuse background (SXRB) emission detected in front of 378 identified shadowing regions during the ROSAT All-Sky Survey (Snowden et al. 2000). This foreground component is principally attributed to the hot gas of the so-called Local Bubble (LB), an irregularly shaped cavity of ~50-150 pc around the Sun, which is supposed to contain ~10^6 K plasma. Our results suggest that the SWCX emission from the heliosphere is bright enough to account for most of the foreground emission towards the majority of low galactic latitude directions, where the LB is the least extended. In a large part of directions with galactic latitude above 30deg the heliospheric SWCX intensity is significantly smaller than the measured one. However, the SWCX R2/R1 band ratio differs slightly from the data in the galactic center direction, and more significantly in the galactic anti-centre direction where the observed ratio is the smallest. Assuming that both SWCX and hot gas emission are present and their relative contributions vary with direction, we tested a series of thermal plasma spectra for temperatures ranging from 10^5 to 10^6.5 K and searched for a combination of SWCX spectra and thermal emission matching the observed intensities and band ratios, while simultaneously being compatible with O VI emission measurements. In the frame of collisional equilibrium models and for solar abundances, the range we derive for hot gas temperature and emission measure cannot reproduce the Wisconsin C/B band ratio. We emphasize the need for additional atomic data, describing consistently EUV and X-ray photon spectra of the charge-exchange emission of heavier solar wind ions.

  19. Energetic ion (>~50kev) and electron (>~40kev) bursts observed by ULYSSES near Jupiter

    Microsoft Academic Search

    G. C. Anagnostopoulos; A. Aggelis; I. Karanikola; P. K. Marhavilas

    2001-01-01

    A careful analysis of data collected by the HISCALE experiment on board Ulysses suggests that the quasi-periodic (Q-P) modulation of several or tens of minutes in flux and\\/or anisotropy\\/spectral observations is an almost permanent characteristic of the energetic (>~50 keV) ion population in the outer and the high latitude middle magnetosphere of Jupiter. In most cases a periodicity of ~5-20

  20. Gamma-Ray Burst Spectra and Time Histories from 2 to 400 keV

    E-print Network

    E. E. Fenimore

    1998-02-12

    The Gamma-Ray burst detector on Ginga consisted of a proportional counter to observe the x-rays and a scintillation counter to observe the gamma-rays. It was ideally suited to study the x-rays associated with gamma-ray bursts (GRBs). Ginga detected 120 GRBs and 22 of them had sufficient statistics to determine spectra from 2 to 400 keV. Although the Ginga and BATSE trigger criteria were very similar, the distribution of spectral parameters was different. Ginga observed bend energies in the spectra down to 2 keV and had a larger fraction of bursts with low energy power law indexes greater than zero. The average ratio of energy in the x-ray band (2 to 10 keV) compared to the gamma-ray band (50 to 300 keV) was 24%. Some events had more energy in the x-ray band than in the gamma-ray band. One Ginga event had a period of time preceding the gamma rays that was effectively pure x-ray emission. This x-ray ``preactivity'' might be due to the penchant for the GRB time structure to be broader at lower energy rather than a different physical process. The x-rays tend to rise and fall slower than the gamma rays but they both tend to peak at about the same time. This argues against models involving the injection of relativistic electrons that cool by synchrotron radiation.

  1. HELIOSPHERIC NEUTRAL ATOM SPECTRA BETWEEN 0.01 AND 6 keV FROM IBEX

    SciTech Connect

    Fuselier, S. A.; Ghielmetti, A. G.; Petrinec, S. M.; Trattner, K. J., E-mail: sfuselier@swri.edu, E-mail: fallegrini@swri.edu [Lockheed Martin Advanced Technology Center, Palo Alto, CA 94304 (United States); and others

    2012-07-20

    Since 2008 December, the Interstellar Boundary Explorer (IBEX) has been making detailed observations of neutrals from the boundaries of the heliosphere using two neutral atom cameras with overlapping energy ranges. The unexpected, yet defining feature discovered by IBEX is a Ribbon that extends over the energy range from about 0.2 to 6 keV. This Ribbon is superposed on a more uniform, globally distributed heliospheric neutral population. With some important exceptions, the focus of early IBEX studies has been on neutral atoms with energies greater than {approx}0.5 keV. With nearly three years of science observations, enough low-energy neutral atom measurements have been accumulated to extend IBEX observations to energies less than {approx}0.5 keV. Using the energy overlap of the sensors to identify and remove backgrounds, energy spectra over the entire IBEX energy range are produced. However, contributions by interstellar neutrals to the energy spectrum below 0.2 keV may not be completely removed. Compared with spectra at higher energies, neutral atom spectra at lower energies do not vary much from location to location in the sky, including in the direction of the IBEX Ribbon. Neutral fluxes are used to show that low energy ions contribute approximately the same thermal pressure as higher energy ions in the heliosheath. However, contributions to the dynamic pressure are very high unless there is, for example, turbulence in the heliosheath with fluctuations of the order of 50-100 km s{sup -1}.

  2. The Hard X-Ray 20-40 keV AGN Luminosity Function

    NASA Astrophysics Data System (ADS)

    Beckmann, V.; Soldi, S.; Shrader, C. R.; Gehrels, N.; Produit, N.

    2006-11-01

    We have compiled a complete extragalactic sample based on ~25,000 deg2 to a limiting flux of 3×10-11 ergs cm-2 s-1 (~7000 deg2 to a flux limit of 10-11 ergs cm-2 s-1) in the 20-40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate for effects of nonuniform exposure. The flux-number relation is best described by a power law with a slope of ?=1.66+/-0.11. The integration of the cumulative flux per unit area leads to f20-40 keV=2.6×10-10 ergs cm-2 s-1 sr-1, which is about 1% of the known 20-40 keV X-ray background. We present the first luminosity function of AGNs in the 20-40 keV energy range, based on 38 extragalactic objects detected by the imager IBIS-ISGRI on board INTEGRAL. The luminosity function shows a smoothly connected double-power-law form with an index of ?1=0.8 below and ?2=2.1 above the turnover luminosity of L*=2.4×1043 ergs s-1. The emissivity of all INTEGRAL AGNs per unit volume is W20-40keV(>1041 ergs s-1)=2.8×1038 ergs s-1 h370 Mpc-3. These results are consistent with those derived in the 2-20 keV energy band and do not show a significant contribution by Compton-thick objects. Because the sample used in this study is truly local (z¯=0.022), only limited conclusions can be drawn for the evolution of AGNs in this energy band.

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

    Microsoft Academic Search

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

    2004-01-01

    The K-L and K-M resonant Raman scattering (RRS) cross-sections have been measured for the first time at the 59.536 keV photon energy in the 70Yb (BK=61.332 keV), 71Lu (BK=63.316 keV) and 72Hf (BK=65.345 keV) elements; BK being the K-shell binding energy. The K-L and K-M RRS measurements have been performed at the 59° and 133° angles, respectively, to avoid interference

  4. Polarized Radiative Capture Reactions below 100 keV, a New Laboratory for Nuclear Physics.

    NASA Astrophysics Data System (ADS)

    Weller, H. R.

    1996-05-01

    Despite the importance of low energy radiative capture reactions in nuclear astrophysics, very little is known and very few measurements have been made below 100 keV. The energy change of a factor of 100 as we go from 1 to 100 keV can be accompanied by huge changes in proton penetrabilities (of the order of 10^8), making extrapolations difficult. Although meson-exchange current effects are known to be important at thermal energies, no studies of these effects have been performed at finite low-energies. The availability of large high-resolution Germanium detectors (HPGe) and high intensity polarized beams has made it possible to begin to study these reactions between 10 and 100 keV in considerable detail. Our study of the D(p, ?)^3He and the ^1H(d, ?)^3He reactions using polarized beams below 80 keV has revealed a wealth of new information. The energy dependence of the cross section below 80 keV was determined experimentally for the first time. Our results indicate an astrophysical S-factor which is 34% smaller than the presently accepted value. Our detailed measurements of cross section, vector and tensor analyzing powers, and gamma-ray polarizations as a function of energy and angle have been compared with the results of new few-body calculations by Schiavilla et al.(R. Schiavilla, CEBAF Theory Group, private communication (1995).) which include Coulomb and MEC effects. Dramatic effects due to the tensor force and the associated two-body currents are observed in the vector and tensor analyzing powers for the first time. A detailed study of the ^7Li(p, ?)^8Be reaction has revealed the presence of a significant p-wave capture amplitude at these energies which affects the extrapolation used to obtain the S-factor. A recent measurement of the ^7Li(p, ?_3)^8Be (2^+, T=0+1) reaction has been performed using polarized protons below 80 keV. This reaction is especially interesting due to its close relationship to the ^7Be(p, ?)^8B (2^+, T=1) reaction, the source of high energy solar neutrinos. The results of this work and preliminary studies of several other reactions below 80 keV will be described. Work partially supported by USDOE grant No. DEFG05-91-ER40619

  5. Degradation of 81 keV 133Xe Gamma-Rays into the 31 keV X-Ray Peak in CsI Scintillators

    SciTech Connect

    Keillor, Martin E.; Cooper, Matthew W.; Hayes, James C.; McIntyre, Justin I.

    2009-12-03

    ABSTRACT Pacific Northwest National Laboratory uses beta-gamma coincidence detectors in a number of xenon sampling and/or measurement systems to enable simultaneous, sensitive measurements of 131Xe, 133Xe, 133mXe, and 135Xe for treaty monitoring applications. In recent years, a new style of beta-gamma detector was developed to improve upon the detector module used in the Automated Radioxenon Sampler/Analyzer. The results of an MCNP5 Monte Carlo simulation of the new detector cell are presented, with particular emphasis on the identification of an energy deposition sequence with the potential to introduce significant error into the detector efficiency calibration. This sequence occurs when an 81 keV gamma from 133Xe is absorbed in an inactive region of the CsI(Na) scintillator, followed by emission of a 31 keV x-ray from cesium (or possibly a 28.5 keV x-ray from iodine). These x-rays add excess counts into the 31 keV peak observed in the decay of 133Xe. The impact of this effect on different efficiency calibration techniques is discussed.

  6. Proposal to isolate the origin of the 17-keV kink in the. beta. spectrum

    SciTech Connect

    Cook, S.; Fink, M. (Department of Physics, University of Texas, Austin, Texas 78712 (United States)); Thomas, S. (Theory Group, Department of Physics, University of Texas, Austin, Texas 78712 (United States)); Wellenstein, H. (Department of Physics, Brandeis University, Waltham, Massachusetts 02254 (United States))

    1992-07-01

    An experiment is proposed which can definitively test for the presence of a 17-keV neutrino in {beta} decay. By measuring the recoil ion direction and energy in coincidence with the emitted electron, the neutrino mass may be reconstructed. This method can also distinguish among more exotic explanations for a 17-keV threshold, such as radiative or Coulomb corrections, a nuclear excitation, or a fourth particle in the decay. Some details of a possible experiment using {sup 35}S are discussed.

  7. Stellar nucleosynthesis and the 24keV neutron capture cross sections of some heavy nuclei

    Microsoft Academic Search

    T. Bradley; Z. Parsa; M. L. Stelts; R. E. Chrien

    1979-01-01

    The neutron capture cross sections of ¹¹²Sn, ¹³°Ba, ¹⁴⁶Nd, ¹⁴⁸Nd, ¹⁸⁶W, ¹⁹°Os, and ¹⁹²Os at 24 keV neutron energy were measured with respect to ¹⁹⁷Au by activation in a 24 keV neutron beam at the Brookhaven High Flux Beam Reactor. The reliability of this technique was verified by remeasuring the cross section of ¹⁸⁶W and comparing it to previous measurements.

  8. Transmission of 1--6keV positrons through thin metal films

    Microsoft Academic Search

    Allen Mills; Robert Wilson

    1982-01-01

    We report measurements of the transmission of 1--6-keV energy positrons through films of Al, Cu, and Si up to 3000 A thick. When the thickness is expressed in terms of mass per unit area, the transmission of Cu and Al is found to be the same within +- 10%. Within a +- 20% precision we observe no effect having to

  9. Radiative n11B capture accounting 21 and 430 keV resonances

    E-print Network

    S. B. Dubovichenko; N. A. Burkova

    2014-03-13

    In the framework of the modified potential cluster model the possibility of describing the available experimental data for the total cross sections for n11B radiative capture at thermal and astrophysical energies were considered with taking into account the 21 and 430 keV resonances.

  10. Interstellar photoelectric absorption cross sections, 0.03-10 keV

    Microsoft Academic Search

    R. Morrison; D. McCammon

    1983-01-01

    An effective absorption cross section per hydrogen atom has been calculated as a function of energy in the 0.03-10 keV range using the most recent atomic cross section and cosmic abundance data. Coefficients of a piecewise polynomial fit to the numerical results are given to allow convenient application in automated calculations.

  11. 900 keV gold ion sputter etching of silicon and metals

    Microsoft Academic Search

    Gary A. Glass; Johnny F. Dias; Alexander D. Dymnikov; Bibhudutta Rout

    2008-01-01

    Au ions (900keV) have been used to directly sputter etch microstructures in silicon, aluminum, copper and silver. The results presented clearly demonstrate that high energy heavy ions can be used to fabricate microstructures in selected metals and silicon in a single step process.

  12. 900 keV gold ion sputter etching of silicon and metals

    Microsoft Academic Search

    Gary A. Glass; Johnny F. Dias; Alexander D. Dymnikov; Bibhudutta Rout

    2008-01-01

    Au ions (900 keV) have been used to directly sputter etch microstructures in silicon, aluminum, copper and silver. The results presented clearly demonstrate that high energy heavy ions can be used to fabricate microstructures in selected metals and silicon in a single step process.

  13. Spectral structure of 245-445 keV electrons and positrons in positron-thorium scattering

    NASA Astrophysics Data System (ADS)

    Bargholtz, Chr.; Holmberg, L.; Johansson, K. E.; Liljequist, D.; Tegnér, P.-E.; Vojdani, D.

    1989-09-01

    Anomalies in low-energy positron scattering from thorium are searched for. The incident positrons were emitted from a 68Ga source with an end-point energy of 1.90 MeV. Coincidences between electrons and positrons in the energy range 245-445 keV were registered in a double beta spectrometer. The electron and positron energy spectra are best described in terms of Bhabha scattering with a small additional structure at an energy of about 320 keV for both the electrons and the positrons. The significance of this peak is estimated to be three standard deviations. The spectrometer was also used in a study of scattering of electrons emitted in the decay of 90Y, with an end-point energy of 2.28 MeV. The electron-electron coincidence spectrum in the energy range 245-445 keV is well described as resulting from Möller scattering alone.

  14. The effects of energy-loss straggling and elastic scattering models on Monte Carlo calculations of dose distribution functions for 10 keV to 1 MeV incident electrons in water

    Microsoft Academic Search

    C. Bousis; D. Emfietzoglou; H. Nikjoo; P. Hadjidoukas; A. Pathak

    2009-01-01

    Accurate simulation of the transport and energy-loss of energetic electrons is an important step in modeling ion-induced effects in materials. Dose distribution functions (or so-called dose point kernels, DPKs) represent one of the most basic and useful quantities for characterizing the spatial distribution of energy deposition in matter. In the present work we investigate the effect on DPK of various

  15. Ion beam-induced anisotropic plastic deformation at 300 keV

    NASA Astrophysics Data System (ADS)

    van Dillen, T.; Polman, A.; van Kats, C. M.; van Blaaderen, A.

    2003-11-01

    Contrary to earlier predictions, ion irradiation at energies as low as 300 keV causes dramatic anisotropic plastic deformation of silica glass. Spherical colloidal silica particles with diameters of 125, 305, and 1030 nm were irradiated with Xe ions at energies in the range 0.3-4.0 MeV at temperatures between 85 and 380 K. Irradiation-induced anisotropic plastic deformation changes the colloid shape from spherical into oblate ellipsoidal at a rate that strongly increases with ion energy. At a fixed fluence, the transverse diameter increases with electronic energy loss. Even at an energy as low as 300 keV large particle anisotropy was found (size aspect ratio of 1.43 at 1×1015 cm-2). The transverse plastic strain gradually decreases with increasing irradiation temperature: it decreases by a factor 4.5 between 85 and 380 K. The data are in agreement with a viscoelastic thermal spike model for anisotropic deformation.

  16. Measurement of the Neutron-Proton and Neutron-Carbon Total Cross Section from 150 to 800 keV

    E-print Network

    B. H. Daub; V. Henzl; M. A. Kovash; J. L. Matthews; Z. W. Miller; K. Shoniyozov; H. Yang

    2013-01-28

    There have been very few measurements of the total cross section for np scattering below 500 keV. In order to differentiate among NN potential models, improved cross section data between 20 and 600 keV are required. We measured the np and nC total cross sections in this energy region by transmission; a collimated neutron beam was passed through CH2 and C samples and transmitted neutrons were detected by a BC-501A liquid scintillator. Cross sections were obtained with a precision of 1.1-2.0% between 150 and 800 keV using ratios of normalized neutron yields measured with and without the scattering samples in the beam. In energy regions where they overlap, the present results are consistent with existing precision measurements, and fill in a significant gap in the data between En = 150 and 500 keV.

  17. Neutron cross sections and average resonance parameters of 238 U for 55- and 144keV neutrons

    Microsoft Academic Search

    L. L. Litvinskii; V. P. Vertebnyi; V. A. Libman; A. V. Murzin

    1987-01-01

    In this connection, the total neutron cross section, the total and differential cross section for elastic scattering of neutrons by 2aaU for neutron energies of 55 and 144 keV, and also the total and differential cross sections for inelastic scattering of neutrons by 2aaU (with excitation of the 2 + level, E u = 45 keV) for E = 144

  18. The ^14N(p,?_o)^15O Reaction below 140 keV

    NASA Astrophysics Data System (ADS)

    Nelson, S. O.; Kelley, J. H.; Canon, R. S.; Schreiber, E. C.; Saburov, K.; Wulf, E. A.; Weller, H. R.; Prior, R. M.; Spraker, M.; Tilley, D. R.

    1999-10-01

    The capture reaction ^14N(p,?)^15O is the limiting reaction in the CNO cycle. Very little data exists at beam energies below the Ep = 278 keV resonance for this reaction(U. Schroder et al., Nucl. Phys. A467) 240 (1987).^,(W. Lamb and R. Hester, Phys. Rev. 108) 1304 (1957).. Using a 140 keV polarized proton beam and a thick frozen trideuterio ammonia (ND_3) target, we have measured the astrophysical S-factor for the reaction relative to the S-factor for the D(p,?)^3He reaction in this energy region. The outgoing gamma rays were detected in a 140% HPGe detector. The D(p,?)^3He reaction also provided a convenient reference for the energy calibration of this detector. Preliminary analysis suggests that the S-factor for the ^14N(p,?_o)^15O reaction in this energy range is significantly larger than previously assumed^2.

  19. Ion beam-induced anisotropic plastic deformation at 300 keV

    Microsoft Academic Search

    T. van Dillen; A. Polman; C. M. van Kats; A. van Blaaderen

    2003-01-01

    Contrary to earlier predictions, ion irradiation at energies as low as 300 keV causes dramatic anisotropic plastic deformation of silica glass. Spherical colloidal silica particles with diameters of 125, 305, and 1030 nm were irradiated with Xe ions at energies in the range 0.3-4.0 MeV at temperatures between 85 and 380 K. Irradiation-induced anisotropic plastic deformation changes the colloid shape

  20. Ion beam-induced anisotropic plastic deformation at 300 keV

    Microsoft Academic Search

    T. van Dillen; A. Polman; C. M. van Kats; A. van Blaaderen

    2003-01-01

    Contrary to earlier predictions, ion irradiation at energies as low as 300 keV causes dramatic anisotropic plastic deformation of silica glass. Spherical colloidal silica particles with diameters of 125, 305, and 1030 nm were irradiated with Xe ions at energies in the range 0.3–4.0 MeV at temperatures between 85 and 380 K. Irradiation-induced anisotropic plastic deformation changes the colloid shape

  1. Hard X-ray (>15 keV) facility for calibration of space astronomy experiments

    Microsoft Academic Search

    F. Frontera; A. Del Guerra; M. Gambaccini; M. Marziani; G. Pasqualini; T. Franceschini; G. Landini; S. Silvestri

    1993-01-01

    Hard X-ray (>15 keV) experiments for space astronomy require a detailed energy calibration in order to determine their true response matrix. To this end, an X-ray facility is built based on the use of a very stable X-ray generator plus an X-ray goniometer for crystal diffraction, that can provide collimated and monochromatic photons with energies in the range from about

  2. Observations of proton spectra (1.0 less than or equal to proton energy less than or equal to 300 keV) and pitch angle distributions at the plasmapause

    NASA Technical Reports Server (NTRS)

    Williams, D. J.; Fritz, T. A.; Konradi, A.

    1972-01-01

    Detailed proton spectral and pitch angle distribution observations were obtained from two proton detectors and a fluxgate magnetometer flown on Small Scientific Satellite A (Explorer 45). The data of interest are from orbit 99 in-bound occurring on 17 December 1971, some 8 hours prior to the sudden commencement of a magnetic storm. The data are consistent with the initiation of ion cyclotron instability when certain requirements are met. These criteria are met initially at the altitude at which the sudden intensity decrease occurs. However, after the initiation of the instability, the linear theory is unable to explain the further evolution of intensities, pitch angle distributions, and energy spectra of the ring current particles.

  3. Upgrade of LAMPF's 750-keV, H sup + transport

    SciTech Connect

    Hurd, J.W.; Browman, A.A.; Jones, K.W. (Los Alamos National Lab., NM (USA)); Jakobson, M.J. (Montana Univ., Missoula, MT (USA))

    1991-01-01

    The results of the upgrade to the 750-keV H{sup +} transport at LAMPF are reported. The transport takes the beam from the exit of the 750-kV column to the entrance of the 201-MHz drift tube linac. Components of the transport are used to bunch the beam, to match the beam to the linac, and to adjust the peak current of the beam. The transport is a critical section of LAMPF's accelerator system; a properly tuned and stable beam significantly reduces high-energy losses in the accelerator. The transport was upgraded to decrease the emittance growth of the beam, to facilitate tuning, and to eliminate the time-dependent transients associated with space-charge neutralization of the beam. The new transport was installed and used for beam operations in 1990. The upgrade design goals were successfully achieved. The unnormalized emittance for 95% of the beam was measured at 0.8 {pi} cm-mrad compared with 1.2 {pi} cm-mrad in the previous transport. 8 refs., 2 figs.

  4. X-ray phase-contrast imaging at 100 keV on a conventional source

    NASA Astrophysics Data System (ADS)

    Thüring, T.; Abis, M.; Wang, Z.; David, C.; Stampanoni, M.

    2014-06-01

    X-ray grating interferometry is a promising imaging technique sensitive to attenuation, refraction and scattering of the radiation. Applications of this technique in the energy range between 80 and 150 keV pose severe technical challenges, and are still mostly unexplored. Phase-contrast X-ray imaging at such high energies is of relevant scientific and industrial interest, in particular for the investigation of strongly absorbing or thick materials as well as for medical imaging. Here we show the successful implementation of a Talbot-Lau interferometer operated at 100 keV using a conventional X-ray tube and a compact geometry, with a total length of 54 cm. We present the edge-on illumination of the gratings in order to overcome the current fabrication limits. Finally, the curved structures match the beam divergence and allow a large field of view on a short and efficient setup.

  5. Development of a Portable 950 keV X-band Linac for NDT

    SciTech Connect

    Natsui, Takuya; Uesaka, Mitsuru; Yamamoto, Tomohiko; Sakamoto, Fumito; Hashimoto, Eiko; Kiwoo, Lee [Nuclear Professional School, the University of Tokyo, 2-22 Shirakata-Shirane, Tokai, Naka, Ibaraki 319-1188 (Japan); Nakamura, Naoki; Yamamoto, Masashi; Tanabe, Eiji [Accuthera Inc. 2-7-6, Kurigi, Asao, Kawasaki, Kanagawa 215-0033 (Japan); Yoshida, Mitsuhiro; Higo, Toshiyasu; Fukuda, Shigeki [High Energy Accelerator Research Organization, KEK 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

    2009-03-10

    We are developing a portable 950 keV X-band (9.4 GHz) linac X-ray source for on-site nondestructive testing of erosion of metal pipes at a petrochemical complex. To develop it, we adopted a compact X-band 9.4 GHz magnetron of 250 kW for RF generation device. The whole device, including power supply and cooling devices, were also downsized. The dose rate of X-ray converted in a tungsten target is designed to be 0.2 Gy/min at 1-m distance. We designed an accelerating tube that uses the {pi} mode for the lower energy part and the {pi}/2 mode cavity for the higher energy. We manufactured the accelerating tube and carried out beam acceleration tests, confirming that the electron beam was accelerated up to 950 keV.

  6. Elemental content from 0 to 500 keV neutrons: Lunar Prospector results

    Microsoft Academic Search

    I. Genetay; S. Maurice; W. C. Feldman; O. Gasnault; D. J. Lawrence; R. C. Elphic; C. d'Uston; A. B. Binder

    2003-01-01

    Neutron spectroscopy is a new way to study planetary bodies that have sufficiently thin atmospheres. This technique was demonstrated for the first time with Lunar Prospector around the Moon. Here, we report results for moderated neutrons having energies from 0 to 500keV that were measured using the anti-coincidence shield (ACS) of the gamma-ray spectrometer. We describe the detection method, followed

  7. A 20 keV electron gun system for the electron irradiation experiments

    Microsoft Academic Search

    S. K. Mahapatra; S. D. Dhole; V. N. Bhoraskar

    2005-01-01

    An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1–20keV, with current upto 50?A. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup

  8. Chemical evolution of frozen methane by keV ion bombardment

    Microsoft Academic Search

    G. Foti; L. Calcagno; F. Z. Zhou; G. Strazzulla

    1987-01-01

    Frozen methane layers at low temperature (~10 K) have been irradiated with high energy ion beams (keV Ar+ and He+). Molecular emission of H2, CH4, C2H2, C2H4 and C2H6 has been detected as a function of ion fluence in the range 1014 ions\\/cm2. Most of the original carbon atoms are bound after ion bombardment to form a hydrogenated amorphous carbon

  9. Acceleration of 100 keV protons using a 5SDH2 Pelletron

    Microsoft Academic Search

    William A. Hollerman; Gary A. Glass; Nancy Ruzycki

    1999-01-01

    The authors successfully accelerated a 100keV proton beam using a model 5SDH-2 Pelletron accelerator, manufactured by National Electrostatics Corporation (NEC). A pseudo-stable 1–2nA beam was delivered on target with a net energy variation of less than 6%. However, the small terminal potential made it impossible to use standard stabilization techniques. Minor adjustments in terminal potential were required every 15min to

  10. Acceleration of 100keV protons using a 5SDH2 Pelletron

    Microsoft Academic Search

    W. A. Hollerman; G. A. Glass; N. Ruzycki

    1999-01-01

    The authors successfully accelerated a 100keV proton beam using a model 5SDH-2 Pelletron accelerator, manufactured by National Electrostatics Corporation (NEC). A pseudo-stable 1-2nA beam was delivered on target with a net energy variation of less than 6%. However, the small terminal potential made it impossible to use standard stabilization techniques. Minor adjustments in terminal potential were required every 15min to

  11. Dose response of thin-film dosimeters irradiated with 80 120 keV electrons

    NASA Astrophysics Data System (ADS)

    Helt-Hansen, Jakob; Miller, Arne; Sharpe, Peter

    2005-12-01

    Thin-film dosimeters (Risø B3 and alanine films) were irradiated at 10 MeV and 80-120 keV electron accelerators, and it has been shown that the radiation response of the dosimeter materials (the radiation chemical yields) are constant at these irradiation energies. However, dose gradients within the dosimeters mean that calibration functions at the lower electron energies will be dependent on both irradiation energy and the required effective point of measurement of the dosimeter. These are general effects that apply to any dosimeters that have non-linear response functions and where dose gradients are present within the dosimeter.

  12. Compact, maintainable 80-KeV neutral beam module

    DOEpatents

    Fink, Joel H. (Livermore, CA); Molvik, Arthur W. (Livermore, CA)

    1980-01-01

    A compact, maintainable 80-keV arc chamber, extractor module for a neutral beam system immersed in a vacuum of <10.sup.-2 Torr, incorporating a nested 60-keV gradient shield located midway between the high voltage ion source and surrounding grounded frame. The shield reduces breakdown or arcing path length without increasing the voltage gradient, tends to keep electric fields normal to conducting surfaces rather than skewed and reduces the peak electric field around irregularities on the 80-keV electrodes. The arc chamber or ion source is mounted separately from the extractor or ion accelerator to reduce misalignment of the accelerator and to permit separate maintenance to be performed on these systems. The separate mounting of the ion source provides for maintaining same without removing the ion accelerator.

  13. Mutagenic effect of a keV range N + beam on mammalian cells

    NASA Astrophysics Data System (ADS)

    Feng, Huiyun; Wu, Lijun; Yu, Lixiang; Han, Wei; Liu, Xuelan; Yu, Zengliang

    2005-07-01

    The radiobiological effects of a keV (5-20 keV) range nitrogen ion (N +) beam on mammalian cells were studied, particularly with regard to the induction of mutation in the cell genome. The experiment demonstrated that the 20 keV N + beam, which resulted in cell death to a certain extent, induced a 2-3 fold increase in the mutation rates at the CD59 gene locus of the mammalian A L cells as compared to the control. Within certain fluence ranges (0-6 × 10 14 N +/cm 2), the cell survival displayed a down-up-down pattern which is similar to the phenomenon known as 'hyper-radiosensitivity' manifested under low-dose irradiation; the CD59 mutation rate firstly showed a gradual rise up to a 3-fold increment above the background level as the ion fluence went up to 4 × 10 14 N +/cm 2, after this peak point however, a downtrend appeared though the ion fluence increased further. It was also observed that the fraction of CD59 mutation bears no proportional relation to ion energy in further experiments of mutation induction by N + beams with the incident energies of 5, 10, 15 and 20 keV at the same fluence of 3 × 10 14 N +/cm 2. Analyses of the deletion patterns of chromosome 11 in CD59- mutants induced by 5-20 keV N + beams showed that these ions did not result in large-size chromosome deletions in this mammalian cell system. A preliminary discussion, suggesting that the mutagenic effect of such low-energy ion influx on mammalian cells could result from multiple processes involving direct collision of particles with cellular DNA, and cascade atomic and molecular reactions due to plentiful primary and secondary particles, was also presented. The study provided the first glimpse into the roles low-energy ions may play in inducing mutagenesis in mammalian cells, and results will be of much value in helping people to understand the contribution of low-energy ions to radiological effects of various ionising radiations.

  14. Lifetime of 981-Kev State in Li-8

    E-print Network

    Throop, M. J.; Youngblood, David H.; Morrison, G. C.

    1971-01-01

    Axgonne National Laboratory, Axgonne, Illinois 60439 (Received 17 November 1970) The lifetime of the 981-keV state in Li produced in the D(Li,p)Li * reaction was mea- sured by the two-backing variant of the Doppler-shift attenuation method... of the Li' first excited state at 981 keV by means of the attenuated-Doppler-shift technique and a comparison of the result with pre- dictions of a shell-model calculation for the 1p shell. ' An upper limit of 35 fsec for this lifetime has been...

  15. ASTRID @ 58 keV — A measurement of Spin-TRansfer coefficients In the fusion reaction D(d?, p?)3H

    NASA Astrophysics Data System (ADS)

    Imig, A.; Düweke, C.; Ley, J.; Pascovici, G.; Zell, K.-O.; Paetz gen. Schieck, H.

    2007-06-01

    We measured the polarization-transfer coefficient Kyy' of the fusion reaction 2H(d?, p?)3H at the fusion relevant energy of Ed = 58 keV at the laboratory reaction angle ? = 45°. The result is compared with theoretical predictions based on Faddeev-Yakubovsky equations, calculated with and without inclusion of the Coulomb interaction, and a prediction based on a T-matrix parametrization of all available data of this reaction at energies below 1500 keV.

  16. Registration of 14.4 keV 57Fe conversional decay after nuclei excitation induced with the help of plasma created by the powerful femtosecond laser pulse

    NASA Astrophysics Data System (ADS)

    Golovin, G.; Uryupina, D.; Volkov, R.; Savel'ev, A.

    2010-04-01

    Plasma created by the femtosecond laser pulse with intensity 1017 W/cm2 was used as a source of protons with mean energy of 26 keV. Conversional deexcitation of 14.4 keV nuclear state of 57Fe, excited by impact of these protons, was observed. Abnormally high energy transfer (up to 70%) from protons to knocked out electrons was also registered.

  17. Electron loss and transfer for 20--110-keV iodine--rare-gas collisions

    SciTech Connect

    Hird, B.; Orakzai, M.W.; Rahman, F.

    1989-05-15

    Atomic cross sections have been measured for the loss and transfer of an electron during a collision between a neutral iodine atom and a rare-gas atom. The neutral iodine beam, with energy between 20 to 110 keV, was unlikely to contain a significant mixture of metastable-state atoms because it was produced by neutralizing a negative-iodine-ion beam. The sigma/sub 0+/ cross section is largest for the argon and krypton targets, not for xenon, as might have been expected. The sigma/sub 0-/ cross section is very small for the light targets and only becomes appreciable for xenon at the highest energy used.

  18. Acceleration of 100 keV protons using a 5SDH-2 Pelletron

    NASA Astrophysics Data System (ADS)

    Hollerman, William A.; Glass, Gary A.; Ruzycki, Nancy

    1999-07-01

    The authors successfully accelerated a 100 keV proton beam using a model 5SDH-2 Pelletron accelerator, manufactured by National Electrostatics Corporation (NEC). A pseudo-stable 1-2 nA beam was delivered on target with a net energy variation of less than 6%. However, the small terminal potential made it impossible to use standard stabilization techniques. Minor adjustments in terminal potential were required every 15 min to maintain beam current and energy. This level of stability is sufficient to deliver a proton fluence of 10 11-10 12 cm -2 to any desired target.

  19. The Hard X-ray 20-40 keV AGN Luminosity Function

    NASA Technical Reports Server (NTRS)

    Beckmann, V.; Soldi, S.; Shrader, C. R.; Gehrels, N.; Produit, N.

    2006-01-01

    We have compiled a complete, significance limited extragalactic sample based on approximately 25,000 deg(sup 2) to a limiting flux of 3 x 10(exp -11) ergs per square centimeter per second. (approximately 7,000 deg(sup 2)) to a flux limit of 10(exp -11) ergs per square centimeter per second)) in the 20 - 40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate for effects of non-uniform exposure. The flux-number relation is best described by a power-law with a slope of alpha = 1.66 plus or minus 0.11. The integration of the cumulative flux per unit area leads to f(sub 20-40 keV) = 2.6 x 10(exp -10) ergs per square centimeter per second per sr(sup -1) which is about 1% of the known 20-40 keV X-ray background. We present the first luminosity function of AGN in the 20-40 keV energy range, based on 68 extragalactic objects detected by the imager IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly connected two power-law form, with an index of gamma (sub 1) = 0.9 below, and gamma (sub 2) = 2.2 above the turn-over luminosity of L(sub *), = 4.6 x 10(sup 43) ergs per second. The emissivity of all INTEGRAL AGNs per unit volume is W(sub 20-40keV)(greater than 10(sup 41) ergs per second) = 2.8 x 10(sup 38) ergs per second h(sup 3)(sub 70) Mpc(sup -3). These results are consistent with those derived in the 2-20keV energy band and do not show a significant contribution by Compton-thick objects. Because the sample used in this study is truly local (z(raised bar) = 0.022)), only limited conclusions can be drawn for the evolution of AGNs in this energy band. But the objects explaining the peak in the cosmic X-ray background are likely to be either low luminosity AGN (L(sub x) less than 10(sup 41) ergs per second) or of other type, such as intermediate mass black holes, clusters, and star forming regions.

  20. Production of a keV X-Ray Beam from Synchrotron Radiation in Relativistic Laser-Plasma Interaction

    E-print Network

    Umstadter, Donald

    Kiselev,3 Fre´deric Burgy,1 Jean-Philippe Rousseau,1 Donald Umstadter,2 and Danie´le Hulin1 1 Laboratoire of synchrotron radiation, which has keV energy and lies within a narrow (50 mrad) cone angle. DOI: 10.1103/Phys

  1. Effective field theory and keV lines from dark matter

    NASA Astrophysics Data System (ADS)

    Krall, Rebecca; Reece, Matthew; Roxlo, Thomas

    2014-09-01

    We survey operators that can lead to a keV photon line from dark matter decay or annihilation. We are motivated in part by recent claims of an unexplained 3.5 keV line in galaxy clusters and in Andromeda, but our results could apply to any hypothetical line observed in this energy range. We find that given the amount of flux that is observable, explanations in terms of decay are more plausible than annihilation, at least if the annihilation is directly to Standard Model states rather than intermediate particles. The decay case can be explained by a scalar or pseudoscalar field coupling to photons suppressed by a scale not far below the reduced Planck mass, which can be taken as a tantalizing hint of high-scale physics. The scalar case is particularly interesting from the effective field theory viewpoint, and we discuss it at some length. Because of a quartically divergent mass correction, naturalness strongly suggests the theory should be cut off at or below the 1000 TeV scale. The most plausible such natural UV completion would involve supersymmetry. These bottom-up arguments reproduce expectations from top-down considerations of the physics of moduli. A keV line could also arise from the decay of a sterile neutrino, in which case a renormalizable UV completion exists and no direct inference about high-scale physics is possible.

  2. Search of keV Sterile Neutrino Warm Dark Matter in the Rhenium and Tritium beta decays

    E-print Network

    de Vega, H J; de Guerra, E Moya; Medrano, M Ramon; Sanchez, N

    2011-01-01

    keV sterile neutrinos are important as extensions of the Standard Model of particle physics and as serious keV dark matter (DM) candidates (Warm DM) in agreement with both cosmological and galaxy observations. We study the possible detection of a keV sterile neutrino through its mixing with a light active neutrino in the Rhenium 187 and Tritium beta decays. The electron low energy beta spectrum 0 keV < T_e < (Q_{beta} - m_s)keV is the region where a sterile neutrino could be detected and its mass m_s measured, (m_s being expected 1 to 10 keV from cosmological and galactic observations and theoretical analysis). This region is away from the near end-point Q_{beta} region suitable to measure the mass of the light active neutrino. In order to analyze the sterile neutrino effect, we introduce the dimensionless ratio R of the sterile neutrino to the active neutrino contribution: R exhibits a constant plateau that starts at momentum p_e = 0 and sharply drops for p_e near its maximum value; R increases with th...

  3. 3.5 keV Galactic Emission Line as a Signal from the Hidden Sector

    E-print Network

    Ning Chen; Zuowei Liu; Pran Nath

    2014-08-07

    An emission line with energy of $E\\sim 3.5$ keV has been observed in galaxy clusters by two experiments. The emission line is consistent with the decay of a dark matter particle with a mass of $\\sim 7$ keV. In this work we discuss the possibility that the dark particle responsible for the emission is a real scalar ($\\rho$) which arises naturally in a $U(1)_X$ Stueckelberg of MSSM. In the MSSM Stueckelberg extension $\\rho$ couples only to other scalars carrying a $U(1)_X$ quantum number. Under the assumption that there exists a vectorlike leptonic generation carrying both $SU(2)_L\\times U(1)_Y$ and $U(1)_X$ quantum numbers, we compute the decay of the $\\rho$ into two photons via a triangle loop involving scalars. The relic density of the $\\rho$ arises via the decay $H^0\\to h^0+ \\rho$ at the loop level involving scalars, and via the annihilation processes of the vectorlike scalars into $\\rho + h^0$. It is shown that the galactic data can be explained within a multicomponent dark matter model where the 7 keV dark matter is a subdominant component constituting only $(1-10)$\\% of the matter relic density with the rest being supersymmetric dark matter such as the neutralino. Thus the direct detection experiments remain viable searches for WIMPs. The fact that the dark scalar $\\rho$ with no interactions with the standard model particles arises from a Stueckelberg extension of a hidden $U(1)_X$ implies that the 3.5 KeV galactic line emission is a signal from the hidden sector.

  4. Comparison of measured and calculated /sup 238/U capture self-indication ratios from 4 to 10 keV

    SciTech Connect

    Perez, R.B.; de Saussure, G.; Yang, J.T.; Munoz-Cobos, J.L.; Todd, J.H.

    1983-01-01

    From 4 keV to 149 keV the /sup 238/U cross sections are represented in ENDF/B-V by unresolved-resonance parameters (URP). The purpose of this representation is to enable the calculation of resonance self-protection as a function of temperature and dilution. Since the URPs are not defined unambiguously by the cross-section data, it is important that the unresolved representation be tested with appropriate experiments, such as capture self-indication ratio (SIR) measurements. In this paper we compare /sup 238/U capture SIR measurements in the 4- to 10-keV energy range with calculations done with ENDF/B-V and with recently published resolved resonance parameters.

  5. Demonstration of a 13-keV Kr K-shell x-ray source at the National Ignition Facility.

    PubMed

    Fournier, K B; May, M J; Colvin, J D; Barrios, M A; Patterson, J R; Regan, S P

    2013-09-01

    We report 3% conversion efficiency of laser energy into Kr K-shell (?13 keV) radiation, consistent with theoretical predictions. This is ?10× greater than previous work. The emission was produced from a 4.1-mm-diameter, 4-mm-tall gas pipe target filled with 1.2 or 1.5 atm of Kr gas. 160 of the National Ignition Facility laser beams deposited ?700 kJ of 3? light into the target in an ?140 TW, 5.0-ns-duration square pulse. The Dante diagnostics measured ?5 TW into 4? solid angle of ?12 keV x rays for ?4 ns, which includes both continuum emission and flux in the Kr He_{?} line at 13 keV. PMID:24125368

  6. Degeneracy at 1871 keV in {sup 112}Cd and implications for neutrinoless double electron capture

    SciTech Connect

    Green, K. L.; Garrett, P. E.; Demand, G. A.; Grinyer, G. F.; Leach, K. G.; Phillips, A. A.; Schumaker, M. A.; Svensson, C. E.; Wong, J. [Department of Physics, University of Guelph, Guelph, Ontario, N1G 2W1 (Canada); Austin, R. A. E.; Colosimo, S. [Department of Astronomy and Physics, Saint Mary's University, Halifax, Nova Scotia, B3H 3C3 (Canada); Ball, G. C.; Bandyopadhyay, D. S.; Hackman, G.; Morton, A. C.; Pearson, C. J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (Canada); Cross, D. [Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6 (Canada); Kulp, W. D.; Wood, J. L. [School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332-0430 (United States); Yates, S. W. [Departments of Chemistry and Physics and Astronomy, University of Kentucky, Lexington, Kentucky 40506-0055 (United States)

    2009-09-15

    High-statistics {beta}-decay measurements of {sup 112}Ag and {sup 112}In were performed to study the structure of the {sup 112}Cd nucleus. The precise energies of the doublet of levels at 1871 keV, for which the 0{sup +} member has been suggested as a possible daughter state following neutrinoless double electron capture of {sup 112}Sn, were determined to be 1871.137(72) keV (0{sub 4}{sup +} level) and 1870.743(54) keV (4{sub 2}{sup +} level). The nature of the 0{sub 4}{sup +} level, required for the calculation of the nuclear matrix element that would be needed to extract a neutrino mass from neutrinoless double electron capture to this state, is suggested to be of intruder origin.

  7. Feasibility study for DEXA using synchrotron CT at 20-35 keV

    NASA Astrophysics Data System (ADS)

    Midgley, S. M.

    2013-02-01

    A nonlinear model for the x-ray linear attenuation coefficient ? is employed for dual energy x-ray analysis (DEXA). Nonlinear simultaneous equations formed by ? and energy dependent model parameters are solved for the electron density Ne and fourth compositional ratio R4 which has the same ‘units’ as the atomic number. Computed tomography data was acquired at 20-35 keV using bending magnet synchrotron radiation, a double crystal monochromator, a rotation stage and an area detector. Test objects contained liquid samples as mixtures of ethanol, water and salt solutions with known density and composition. Various noise sources are identified and give ? uncertainties of 1-2%. A fan beam geometry allowed the detection of forward scattered radiation with measured ? being 6% lower than expectations for a narrow beam. Energy dependent model parameters were obtained by solving linear simultaneous equations formed by ? and material parameters based upon Ne and R4. DEXA accuracy was studied as a function of photon energy and sample composition. Propagation of errors analysis identifies the importance of the fractional compositional cross-products whose difference at the two beam energies should exceed 0.1, requiring 10 keV or more separation. For a reasonable approximation for the adjustable model parameters, the mean difference between the DEXA solution and true values (?Ne, ?R4) are (1.0%, 0.5%) for soft tissue and (1.5%, 0.8%) for bone like samples.

  8. Characterization of the high-Z 0.9- to 1.0MA x-pinch source in the 0.15- to 500keV region: possible applications of the high-current x-pinch as the subkeV to 10keV radiation driver and the 50- to 100keV backlighter

    Microsoft Academic Search

    Victor L. Kantsyrev; Dmitry A. Fedin; Alla S. Shlyaptseva; Stephanie B. Hansen; Nick D. Ouart

    2004-01-01

    Experimental results of complex studies of x-ray\\/EUV radiation from hot dense x-pinch Ti, Fe, Mo, and W plasmas generated by a pulse-powered z-pinch machine with Imax~0.9 ÷ 1.0 MA and a current rise time of 100 ns are overviewed. Structures and spatial dimensions of 0.9-1.0 MA x-pinch sources in a wide energy range of 0.15 - 0.6 keV, 1-10 keV

  9. Rayleigh, Compton and K-shell radiative resonant Raman scattering in 83Bi for 88.034 keV ?-rays

    Microsoft Academic Search

    Sanjeev Kumar; Veena Sharma; D. Mehta; Nirmal Singh

    2007-01-01

    The Rayleigh, Compton and K-shell radiative resonant Raman scattering cross-sections for the 88.034keV ?-rays have been measured in the 83Bi (K-shell binding energy=90.526keV) element. The measurements have been performed at 130° scattering angle using reflection-mode geometrical arrangement involving the 109Cd radioisotope as photon source and an LEGe detector. Computer simulations were exercised to determine distributions of the incident and emission

  10. Rayleigh, Compton and K-shell radiative resonant Raman scattering in 83Bi for 88.034 keV gamma-rays

    Microsoft Academic Search

    Sanjeev Kumar; Veena Sharma; D. Mehta; Nirmal Singh

    2007-01-01

    The Rayleigh, Compton and K-shell radiative resonant Raman scattering cross-sections for the 88.034 keV gamma-rays have been measured in the 83Bi (K-shell binding energy = 90.526 keV) element. The measurements have been performed at 130° scattering angle using reflection-mode geometrical arrangement involving the 109Cd radioisotope as photon source and an LEGe detector. Computer simulations were exercised to determine distributions of

  11. Neutron transmission and capture measurements and analysis of /sup 60/Ni from 1 to 450 keV

    SciTech Connect

    Perey, C.M.; Harvey, J.A.; Macklin, R.L.; Winters, R.R.; Perey, F.G.

    1982-11-01

    High-resolution transmission and capture measurements of /sup 60/Ni-enriched targets have been made at the Oak Ridge Electron Linear Accelerator (ORELA) from a few eV to 1800 keV in transmission and from 2.5 keV to 5 MeV in capture . The transmission data from 1 to 450 keV were analyzed with a multi-level R-matrix code which uses the Bayes' theorem for the fitting process. This code provides the energies and neutron widths of the resonances inside the 1- to 450-keV region as well as a possible parameterization for outside resonances to describe the smooth cross section in this region. The capture data were analyzed with a least-squares fitting code using the Breit-Wigner formula. From 2.5 to 450 keV, 166 resonances were seen in both sets of data. Correspondence between the energy scales shows a discontinuity around 300 keV which makes the matching of resonances at higher energies difficult. Eighty-nine resonances were seen in the capture data only. Average parameters for the 30 observed s-wave resonances were deduced. The average level spacing D/sub 0/ was found to be equal to 15.2 +- 1.5 keV, the strength function, S/sub 0/, equal to (2.2 +- 0.6) x 10/sup -4/ and the average radiation width, GAMMA/sub ..gamma../, equal to 1.30 +- 0.07 eV. The staircase plot of the reduced level widths and the plot of the Lorentz-weighted strength function averaged over various energy intervals show possible evidence for doorway states. The level densities calculated with the Fermi-gas model for l = 0 and for l > 0 resonances were compared with the cumulative number of observed resonances, but the analysis is not conclusive. The average capture cross section as a function of the neutron incident energy is compared to the tail of the giant electric dipole resonance prediction.

  12. Asymmetric 511 keV Positron Annihilation Line Emission from the Inner Galactic Disk

    NASA Technical Reports Server (NTRS)

    Skinner, Gerry; Weidenspointner, Georg; Jean, Pierre; Knodlseder, Jurgen; Ballmoos, Perer von; Bignami, Giovanni; Diehl, Roland; Strong, Andrew; Cordier, Bertrand; Schanne, Stephane; Winkler, Christoph

    2008-01-01

    A recently reported asymmetry in the 511 keV gamma-ray line emission from the inner galactic disk is unexpected and mimics an equally unexpected one in the distribution of LMXBs seen at hard X-ray energies. A possible conclusion is that LMXBs are an important source of the positrons whose annihilation gives rise to the line. We will discuss these results, their statistical significance and that of any link between the two. The implication of any association between LMXBs and positrons for the strong annihilation radiation from the galactic bulge will be reviewed.

  13. Emission of secondary ions after grazing impact of keV ions on solid surfaces

    NASA Astrophysics Data System (ADS)

    Nakajima, K.; Lienemann, J.; Eberlein, P.; Kimura, K.; Maass, K.; Winter, H.

    2014-12-01

    We have scattered He+ and Ar+ ions with energies of 10 and 20 keV from solid surfaces and investigated by means of a quadrupole mass spectrometer the emission of secondary ions. Compared to the established method of secondary ion mass spectroscopy (SIMS), the impact of ions proceeds under a grazing angle of incidence of about 2°. In experiments with a Cu(1 0 0) target covered with an ultrathin Fe3O4 film as well as ZnO and ZnMgO surfaces we have explored some basic features of this variant of SIMS concerning the potential application as surface analytical tool.

  14. Solution of controversy over 1583-keV levels in 204Pb

    NASA Astrophysics Data System (ADS)

    Trzaska, W. H.; Julin, R.; Kantele, J.; Kumpulainen, J.

    1989-09-01

    Data from 204Pb(p,p')204Pb conversion-electron and gamma-ray experiments, together with previous results, prove the existence of two levels (0+ and 2+) at 1583-keV excitation energy in 204Pb. Modified values (limits) of the ?221 and X211 are 0.00130.073. New experimental evidence indicates that all the three observed excited O+ states in 204Pb can be explained as belonging to the four-neutron-hole valence space and, therefore, there is no clear candidate for the proton 2p-2h intruder state in this nucleus.

  15. The effect of 1 to 5 keV electrons on the reproductive integrity of microorganisms

    NASA Technical Reports Server (NTRS)

    Barengoltz, J. B.; Brady, J.

    1977-01-01

    Microorganisms were exposed to simulated space environment in order to assess the effect of electrons in the energy range 1 to 5 keV on their colony-forming ability. The test system consisted of an electron gun and power supply, a dosimetry subsystem, and a vacuum subsystem. The system was capable of current densities ranging from 0.1 nA/sq cm to 5 micro A/sq cm on a 25 sq on target and an ultimate vacuum of 0.0006 N/sq m (0.000004 torr). The results of the experimental program show a significant reduction in microbial reproductive integrity.

  16. Development of a modular CdTe detector plane for gamma-ray burst detection below 100 keV

    E-print Network

    Ehanno, M; Barret, D; Lacombe, K; Pons, R; Rouaix, G; Gevin, O; Limousin, O; Lugiez, F; Bardoux, A; Penquer, A

    2007-01-01

    We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4x4 mm2, 1 mm thickness) produced by ACRORAD Co. LTD. in Japan. These detectors offer good energy response up to 100 keV. Each XRDPIX is readout by the very low noise front-end electronics chip IDeF-X, currently under development at CEA/DSM/DAPNIA. In this paper, we describe the design of XRDPIX, the main features of the IDeF-X chip, and will present preliminary results of the reading out of one CdTe Schottky detector by the IDeF-X V1.0 chip. A low-energy threshold around 2.7 keV has been measured. This is to be compared with the 12-15 keV threshol...

  17. Development of a modular CdTe detector plane for gamma-ray burst detection below 100 keV

    E-print Network

    M. Ehanno; C. Amoros; D. Barret; K. Lacombe; R. Pons; G. Rouaix; O. Gevin; O. Limousin; F. Lugiez; A. Bardoux; A. Penquer

    2007-01-15

    We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4x4 mm2, 1 mm thickness) produced by ACRORAD Co. LTD. in Japan. These detectors offer good energy response up to 100 keV. Each XRDPIX is readout by the very low noise front-end electronics chip IDeF-X, currently under development at CEA/DSM/DAPNIA. In this paper, we describe the design of XRDPIX, the main features of the IDeF-X chip, and will present preliminary results of the reading out of one CdTe Schottky detector by the IDeF-X V1.0 chip. A low-energy threshold around 2.7 keV has been measured. This is to be compared with the 12-15 keV threshold of the ISGRI-INTEGRAL and BAT-SWIFT instruments, which both use similar detector material.

  18. Measurement of the X-ray mass attenuation coefficients of silver in the 5-20?keV range.

    PubMed

    Islam, M Tauhidul; Tantau, Lachlan J; Rae, Nicholas A; Barnea, Zwi; Tran, Chanh Q; Chantler, Christopher T

    2014-03-01

    The X-ray mass attenuation coefficients of silver were measured in the energy range 5-20?keV with an accuracy of 0.01-0.2% on a relative scale down to 5.3?keV, and of 0.09-1.22% on an absolute scale to 5.0?keV. This analysis confirms that with careful choice of foil thickness and careful correction for systematics, especially including harmonic contents at lower energies, the X-ray attenuation of high-Z elements can be measured with high accuracy even at low X-ray energies (<6?keV). This is the first high-accuracy measurement of X-ray mass attenuation coefficients of silver in the low energy range, indicating the possibility of obtaining high-accuracy X-ray absorption fine structure down to the L1 edge (3.8?keV) of silver. Comparison of results reported here with an earlier data set optimized for higher energies confirms accuracy to within one standard error of each data set collected and analysed using the principles of the X-ray extended-range technique (XERT). Comparison with theory shows a slow divergence towards lower energies in this region away from absorption edges. The methodology developed can be used for the XAFS analysis of compounds and solutions to investigate structural features, bonding and coordination chemistry. PMID:24562564

  19. Differential Cross Sections for Ionization of Argon by 1 keV Positron and Electron Impact

    NASA Astrophysics Data System (ADS)

    Gavin, J.; DuBois, R. D.; de Lucio, O. G.

    2014-04-01

    Differential information was generated by establishing coincidences and imposing conditions on data recorded for target ions, scattered projectiles, and ejected electrons, as a function of projectile energy loss and scattering angles; in order to describe the interaction between a positron (electron) 1 keV beam and a simple Ar jet. Single ionization triply differential cross section (TDCS) results exhibit two distinct regions (lobes) for which binary (events arising from 2-body interaction) and recoil (events which can only be produced by many-body interactions) interactions are associated. Results indicate that binary events are significantly larger for positron impact, in accordance with theoretical predictions. A similar feature is found for different energy losses and scattering angles. Intensity of the recoil lobe for both projectiles, positron and electron, is observed to depend on the energy loss and scattering angle. Also, it can be noticed that for positron impact the recoil interactions intensity is larger than that observed for electron impact.

  20. A Radio Frequency Helical Deflector for keV Electrons

    E-print Network

    Gevorgian, Leckdar; Kakoyan, Vanik; Margaryan, Amur; Annand, John

    2014-01-01

    This paper describes a helical deflector to perform circular sweeps of keV electrons by means of radio frequency fields in a frequency range 500-1000 MHz. By converting the time dependence of incident electrons to a hit position dependence on a circle, this device can potentially achieve extremely precise timing. The system can be adjusted to the velocity of the electrons to exclude the reduction of deflection sensitivity due to finite transit time effects. The deflection electrodes form a resonant circuit, with quality factor Q in excess of 100, and at resonance the sensitivity of the deflection system is around 1~mm per V of applied RF input.

  1. A radio frequency helical deflector for keV electrons

    NASA Astrophysics Data System (ADS)

    Gevorgian, L.; Ajvazyan, R.; Kakoyan, V.; Margaryan, A.; Annand, J. R. M.

    2015-06-01

    This paper describes a helical deflector to perform circular sweeps of keV electrons by means of radio frequency fields in a frequency range of 500-1000 MHz. By converting the time dependence of incident electrons to a hit position dependence on a circle, this device can potentially achieve extremely precise timing. The system can be adjusted to the velocity of the electrons to exclude the reduction of deflection sensitivity due to finite transit time effects. The deflection electrodes form a resonant circuit, with quality factor Q in excess of 100, and at resonance the sensitivity of the deflection system is around 1 mm per V of applied RF input.

  2. Irradiation cascades in cementite: 0.1-10 keV Fe recoils

    NASA Astrophysics Data System (ADS)

    Henriksson, K. O. E.; Nordlund, K.

    2012-04-01

    Cementite Fe3C is a metastable carbide present in many steels. Depending on the treatment, the cementite can give rise to varying microstructures such as bainite and pearlite, to name a few. Cementite - being harder than pure iron - makes the resulting steel harder and tougher, enabling it to be used as a construction steel. This type of steels can be used to build fission reactors and may be used for future fusion reactors, where they will be subjected to neutron irradiation from the core. In this work we use molecular dynamics simulations to study the response of pure cementite when Fe atoms are knocked out of their lattice sites by neutrons. The Fe recoils have an energy varying between 100 and 10 keV. It is also shown that defects in cementite are roughly one order of magnitude more aboundant than those in pure iron, even when using the same irradiation conditions and ion energies of at least 5 and 10 keV.

  3. Investigations of ripple pattern formation on Germanium surfaces using 100-keV Ar+ ions

    NASA Astrophysics Data System (ADS)

    Sulania, Indra; Agarwal, Dinesh; Husain, Mushahid; Avasthi, Devesh Kumar

    2015-02-01

    We have investigated the formation of nanoripples on the surface of germanium, Ge(100), due to the effect of 100-keV Ar + ion irradiation. The irradiation was carried out at different incidence angles from 0° to 75° in steps of 15° with respect to the surface normal with a fixed ion fluence of approximately 3 × 1017 ions/cm2. Atomic force micrographs show an increase in surface roughness from 0.5 to 4.3 nm for the pristine sample and the sample irradiated at 60° incidence angle due to cos-1( ?) dependence on sputtering yield. With increase in angle of incidence, there is transition observed from nanodots to aligned nanodots perpendicular to the direction of the beam. There is an increase in size of the nanostructures observed from 44 to 103 nm with angle of incidence. The formation of nanoripples initiates at an angle of ? ~ 45°. Ripple pattern formation has taken place on the Ge surface in the energy regime of 100 keV as compared to the other reports which had been carried out using very low energy ions. Raman spectra reveal that the near surface of crystalline Ge samples becomes amorphous due to interaction of Ar+ ions due to creation of defects through collision cascades.

  4. Hydrogen-Atom Excitation and Ionization by Proton Impact in 50-Kev to 200-Kev Energy Region

    E-print Network

    Fitchard, E.; Ford, A. Lewis; Reading, John F.

    1977-01-01

    = ~, which is done by taking a pro- duct of matrices. At t= - the system starts out in some specific initial state. A U-matrix method was first used in Zimmerman's thesis for the pro- ton-hydrogen problem and has since been applied independently... and D. Dinwiddie,J. Chem. Phys. 57, 4919 (1972). 2J. F. Reading, A. L. Ford, and E. F. Fitchard, Phys. Hev. Lett. 36, 573 (1976); Phys. Aev. A 16, 133 (1977). 3I. M. Cheshire and E. C. Sullivan, Phys. Rev. 160, 4 (1967). E. H. Zimmerman, thesis...

  5. 3.55 keV photon lines from axion to photon conversion in the Milky Way and M31

    NASA Astrophysics Data System (ADS)

    Conlon, Joseph P.; Day, Francesca V.

    2014-11-01

    We further explore a scenario in which the recently observed 3.55 keV photon line arises from dark matter decay to an axion-like particle (ALP) of energy 3.55 keV, which then converts to a photon in astrophysical magnetic fields. This ALP scenario is well-motivated by the observed morphology of the 3.55 keV flux. For this scenario we study the expected flux from dark matter decay in the galactic halos of both the Milky Way and Andromeda (M31). The Milky Way magnetic field is asymmetric about the galactic centre, and so the resulting 3.55 keV flux morphology differs significantly from the case of direct dark matter decay to photons. However the Milky Way magnetic field is not large enough to generate an observable signal, even with ASTRO-H. In contrast, M31 has optimal conditions for a ? ? conversion and the intrinsic signal from M31 becomes two orders of magnitude larger than for the Milky Way, comparable to that from clusters and consistent with observations.

  6. Resolved resonance parameters for uranium 238 from 4 to 6 keV

    SciTech Connect

    Olsen, D.K.; Meszaros, P.S.

    1982-01-01

    Neutron widths for 145 resonances from 4 to 6 keV are reported from a least-squares shape analysis of the ORELA 150-m, 4-sample /sup 238/U transmission data. The resultant s-wave strength function from 4 to 6 keV is found to be substantially smaller than that from 0 to 4 keV.

  7. Absolute ionization yield of 6.7 keV argon atoms stopping in liquid argon

    NASA Astrophysics Data System (ADS)

    Sorensen, Peter

    2014-03-01

    We have made a first measurement of the total electronic energy loss of low-energy argon atoms stopping in liquid argon. The importance of the measurement is underscored by the fact that state of the art theoretical treatment of this problem is only approximate. The results are of interest not only to condensed matter theory, but as a crucial calibration for experiments seeking to directly detect hypothetical dark matter particles, or coherent elastic neutrino nucleus scattering. Using quasi mono-energetic neutrons from a collimated and filtered 7Li(p,n) source, we measured the absolute ionization yield of nuclear recoils in liquid argon at 6.7 keV at applied electric fields ranging from 200-2130 V/cm. We will discuss the experimental setup used for these measurements, our findings and their implications, and finally our recent efforts to apply this technique to liquid xenon.

  8. Point Defect Cluster Formation in Iron Displacement Cascades Up to 50 keV

    SciTech Connect

    Stoller, R.E.

    1998-11-30

    The results of molecular dynamics displacement cascade simulations in iron at energies up to 50 keV and temperatures of 100, 600, and 900K are summarized, with a focus on the characterization of interstitial and vacancy clusters that are formed directly within the cascade. The fraction of the surviving point defects contained in clusters, and the size distributions of these in-cascade clusters have been determined. Although the formation of true vacancy clusters appears to be inhibited in iron, a significant degree of vacancy site correlation was observed. These well correlated arrangements of vacancies can be considered nascent clusters, and they have been observed to coalesce during longer term Monte Carlo simulations which permit short range vacancy diffusion. Extensive interstitial clustering was observed. The temperature and cascade energy dependence of the cluster size distributions are discussed in terms of their relevance to microstructural evolution and mechanical property changes in irradiated iron-based alloys.

  9. Observation of an ionospheric acceleration mechanism producing energetic (keV) ions primarily normal to the geomagnetic field direction

    Microsoft Academic Search

    R. D. Sharp; R. G. Johnson; E. G. Shelley

    1977-01-01

    O\\/sup +\\/ ions with energies of approximately 1 keV have been observed flowing upward out of the ionosphere with a pitch angle distribution having a minimum along the magnetic field direction and maxima in about 130°⁻⁻¹⁴°sup 0\\/ range. The measurements were obtained with an energetic ion mass spectrometer experiment on the satellite 1976-65B at an altitude of about 7600 km

  10. Measurement of Nuclear Inelastic Scattering Cross Section of Thorium232 for 144keV Si-Filtered Neutrons

    Microsoft Academic Search

    Yoshiaki FUJITA; Takaaki OHSAWA; Robert M. BRUGGER; Don M. ALGER; William H. MILLER

    1983-01-01

    The nuclear inelastic scattering cross section of Th has been measured at 144 keV using a Si-filtered neutron beam from the University of Missouri Research Reactor (MURR). The energy spectrum of the scattered neutrons was measured with a spherical hydrogen-gas counter and a pulse-height-unfolding procedure. Data were taken at nine scattering angles from 30° to 150° in 15° increments. The

  11. A Monte Carlo study of cellular S-factors for 1 keV to 1 MeV electrons

    Microsoft Academic Search

    C. Bousis; D. Emfietzoglou; P. Hadjidoukas; H. Nikjoo

    2009-01-01

    A systematic study of cellular S-factors and absorbed fractions for monoenergetic electrons of initial energy from 1 keV to 1 MeV is presented. The calculations are based on our in-house Monte Carlo codes which have been developed to simulate electron transport up to a few MeV using both event-by-event and condensed-history techniques. An extensive comparison with the MIRD tabulations is

  12. Spectroscopy of Hard X-Rays (2 15 keV) Generated by Focusing Femtosecond Laser on Metal Targets

    Microsoft Academic Search

    Yasushi Fujimoto; Yoichiro Hironaka; Kazutaka G. Nakamura; Ken-ichi Kondo; Masatake Yoshida; Masayuki Ohtani; Hiroshi Tsunemi

    1999-01-01

    Spectroscopy of hard X-rays generated by focusing a femtosecond laser (42 fs at 780 nm) onto metal targets consisting elements of various atomic number (Z) is carried out in the energy range between 2 and 15 keV using a direct-detection charge-coupled-device camera.Sharp K-shell line emissions are observed for X-rays generated from medium-Z targets (Ti, Fe, Ni, Cu and Zn), which

  13. Prototype detector for 6keV x-rays using nine series arrays of tunnel junctions

    Microsoft Academic Search

    William C. Barber; Roger W. Bland; Robert T. Johnson; Kenneth E. Laws; Julie S. Lee; Simon E. Labov; Carl A. Mears

    1994-01-01

    We have fabricated a device consisting of nine arrays of series- connected superconducting aluminum tunnel junctions on a thin sapphire substrate, as a detector of 6-keV X-rays. Tunnel junctions are of interest as particle detectors because their theoretical minimum excitation energy is on the order of one milli-electron volt, a factor of one thousand lower than conventional semiconductor detectors. We

  14. A cryogenic electrostatic trap for long-time storage of keV ion beams

    NASA Astrophysics Data System (ADS)

    Lange, M.; Froese, M.; Menk, S.; Varju, J.; Bastert, R.; Blaum, K.; López-Urrutia, J. R. Crespo; Fellenberger, F.; Grieser, M.; von Hahn, R.; Heber, O.; Kühnel, K.-U.; Laux, F.; Orlov, D. A.; Rappaport, M. L.; Repnow, R.; Schröter, C. D.; Schwalm, D.; Shornikov, A.; Sieber, T.; Toker, Y.; Ullrich, J.; Wolf, A.; Zajfman, D.

    2010-05-01

    We report on the realization and operation of a fast ion beam trap of the linear electrostatic type employing liquid helium cooling to reach extremely low blackbody radiation temperature and residual gas density and, hence, long storage times of more than 5 min which are unprecedented for keV ion beams. Inside a beam pipe that can be cooled to temperatures <15 K, with 1.8 K reached in some locations, an ion beam pulse can be stored at kinetic energies of 2-20 keV between two electrostatic mirrors. Along with an overview of the cryogenic trap design, we present a measurement of the residual gas density inside the trap resulting in only 2×103 cm-3, which for a room temperature environment corresponds to a pressure in the 10-14 mbar range. The device, called the cryogenic trap for fast ion beams, is now being used to investigate molecules and clusters at low temperatures, but has also served as a design prototype for the cryogenic heavy-ion storage ring currently under construction at the Max-Planck Institute for Nuclear Physics.

  15. An All-sky Survey for Tens of keV

    NASA Astrophysics Data System (ADS)

    Gruber, D. E.; Matteson, J.; Coburn, W.; Heindl, W.; Pelling, M.; Peterson, L. E.; Rothschild, R. E.; Skelton, T.; Hink, P.

    The HEXIS (High Energy X-Ray Imaging Spectrometer) is a MIDEX-class mission concept to perform a deep survey and continuous monitoring of nearly the entire sky in the 5-200 keV band. It uses arrays of position-sensitive Cadmium-Zinc Telluride (CZT) detectors and coded masks to achieve 26' resolution and a 5 sigma sensitivity (> 20 keV) of 4 milliCrab in one day and 0.2 milliCrab in one year. With these capabilities it is estimated that ~ 5000 sources can be discovered and localized and have their spectra and variability characterized. Hundreds of gamma-ray bursts would be detected each year and localized to < 20'. HEXIS also contains a narrow field, 5(deg) , coded mask imager for detailed studies of selected regions. This has three arc minute resolution and is seven times more sensitive than the all-sky system. The HEXIS detector concept uses crossed strip readout to achieve 0.5 mm resolution pixels for large area arrays, ~ 400 cm(2) . This technique is under development at UCSD and Washington University. Detectors have been studied with tuneable monochromatic x-ray beams and mapped with finely collimated 30 micron beams. These results show that the crossed strip readout has the necessary spatial and spectral characteristics. The HEXIS concept is described and results are presented on the detectors' spatial and spectral properties.

  16. Low noise scintillation detectors with a P-47 thin layer screen for electrons of several keV

    NASA Astrophysics Data System (ADS)

    Kajcsos, Zs.; Meisel, W.; Griesbach, P.; Gütlich, P.; Sauer, Ch.; Kurz, R.; Hildebrand, K.; Albrecht, R.; Ligtenberg, M. A. C.

    1994-09-01

    The applicability of a low-noise scintillation detector (ScD) for the registration of electrons of several keV energy has been studied employing photomultipliers (PM) of different types and sizes. With the application of a sedimented P-47 scintillation screen, the values of the low-energy sensitivity limit and those of the light conversion coefficient were determined as about 2.7-4.7 keV and 2.8-6.6 photoelectrons/keV, respectively, for the set of PM's (Philips-Valvo XP 2020, Philips-Valvo XP 2052, Philips-Valvo XP 2972, EMI 9124a) studied. It is concluded that such scintillation detectors might be used advantageously as electron counters in the range of E > 5 keV. Applications below this kinetic energy value are also feasible when applying a floating acceleration of several kV to the ScD — a voltage much lower than the values required for Everhart-Thornley detectors.

  17. Optima MDxt: A high throughput 335 keV mid-dose implanter

    SciTech Connect

    Eisner, Edward; David, Jonathan; Justesen, Perry; Kamenitsa, Dennis; McIntyre, Edward; Rathmell, Robert; Ray, Andrew; Rzeszut, Richard [Axcelis Technologies, Inc., 108 Cherry Hill Drive, Beverly, MA 01915 (United States)

    2012-11-06

    The continuing demand for both energy purity and implant angle control along with high wafer throughput drove the development of the Axcelis Optima MDxt mid-dose ion implanter. The system utilizes electrostatic scanning, an electrostatic parallelizing lens and an electrostatic energy filter to produce energetically pure beams with high angular integrity. Based on field proven components, the Optima MDxt beamline architecture offers the high beam currents possible with singly charged species including arsenic at energies up to 335 keV as well as large currents from multiply charged species at energies extending over 1 MeV. Conversely, the excellent energy filtering capability allows high currents at low beam energies, since it is safe to utilize large deceleration ratios. This beamline is coupled with the >500 WPH capable endstation technology used on the Axcelis Optima XEx high energy ion implanter. The endstation includes in-situ angle measurements of the beam in order to maintain excellent beam-to-wafer implant angle control in both the horizontal and vertical directions. The Optima platform control system provides new generation dose control system that assures excellent dosimetry and charge control. This paper will describe the features and technologies that allow the Optima MDxt to provide superior process performance at the highest wafer throughput, and will provide examples of the process performance achievable.

  18. ASTRID at 58 keV - A measurement of Spin-TRansfer coefficients In the fusion reaction D(d-vector, p-vector)3H

    SciTech Connect

    Imig, A. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany); Department of Physics and Astronomy, University of North Carolina at Chapel Hill, 27599 (United States); Triangle Universities Nuclear Laboratory, Durham, North Carolina 27708 (United States); Dueweke, C.; Ley, J.; Pascovici, G.; Zell, K.-O.; Paetz gen Schieck, H. [Institut fuer Kernphysik, Universitaet zu Koeln, Zuelpicher Str. 77, 50937 Koeln (Germany)

    2007-06-13

    We measured the polarization-transfer coefficient K{sub y}{sup y'} of the fusion reaction 2H(d-vector, p-vector)3H at the fusion relevant energy of Ed = 58 keV at the laboratory reaction angle {theta} = 45 deg. The result is compared with theoretical predictions based on Faddeev-Yakubovsky equations, calculated with and without inclusion of the Coulomb interaction, and a prediction based on a T-matrix parametrization of all available data of this reaction at energies below 1500 keV.

  19. Measurement of the polarization resulting from the scattering of 1250-keV gamma rays from bound electrons in lead 

    E-print Network

    Hamilton, Michael Clinton

    1966-01-01

    keV 12 Range of Angular Acceptance d&& for the 600-keV Region 35 13 Range of Angular Acceptance 68 for the 900-keV Region 36 14 Percent Polarization of Gamma Rays Resulting from the Scattering of 1250-keV Gamma Rays through 90' from Lead . 37... Measurement of S' to be Used with the Measure- ment for 1250-keV Gamma Rays Scattered through 90' in the 900-keV Region 40 IV Measurement of S for 600-keV Photons Resulting from the Scattering of 1250-keV Gamma Rays through 56' by Aluminum 41 V...

  20. High-resolution spectra of 20-300 keV hard X-rays from electron precipitation over Antarctica

    SciTech Connect

    Smith, D.M. [Univ. of Maryland, College Park, MD (United States)] [Univ. of Maryland, College Park, MD (United States); Lin, R.P. [Univ. of California, Berkeley, CA (United States)] [Univ. of California, Berkeley, CA (United States); Hurley, A.K. [Univ. of California, Berkeley, CA (United States)] [and others] [Univ. of California, Berkeley, CA (United States); and others

    1995-10-01

    In December 1990, a set of liquid-nitrogen-cooled germanium hard X-ray and gamma-ray spectrometers was flown aboard a high-altitude balloon from McMurdo, Antarctica, for solar, astrophysical, and terrestrial observations. This flight was the first circumnavigation ({approximately}9-day duration) of the Antarctic continent by a large (800,000-cubic-meter) balloon. Bremsstrahlung hard X-ray emission extending up to {approximately}300 keV, from the precipitation of high-energy electrons, was observed on six separate occasions over the auroral zone, all during low geomagnetic activity (K{sub p}{le} 2+). All events were consistent with emission at the trapping boundary; observation over the polar cap showed no precipitation. The authors present the first high-resolution ({Delta}E {approximately}2 keV) full width at half maximum (FWHM) spectra of this hard X-ray emission in the energy range 20-300 keV. The observed count spectra are deconvolved by model-independent techniques to photon spectra and then to the precipitating electron spectra. The spectral hardness shows all inverse relation with L as expected. This result suggests that high-resolution spectroscopy could be extremely effective in characterizing electron precipitation if coupled with imaging capability. 26 refs., 9 figs., 1 tab.

  1. Contrasting physics in wire array z pinch sources of 1-20 keV emission on the Z facilitya)

    NASA Astrophysics Data System (ADS)

    Ampleford, D. J.; Jones, B.; Jennings, C. A.; Hansen, S. B.; Cuneo, M. E.; Harvey-Thompson, A. J.; Rochau, G. A.; Coverdale, C. A.; Laspe, A. R.; Flanagan, T. M.; Moore, N. W.; Sinars, D. B.; Lamppa, D. C.; Harding, E. C.; Thornhill, J. W.; Giuliani, J. L.; Chong, Y.-K.; Apruzese, J. P.; Velikovich, A. L.; Dasgupta, A.; Ouart, N.; Sygar, W. A.; Savage, M. E.; Moore, J. K.; Focia, R.; Wagoner, T. C.; Killebrew, K. L.; Edens, A. D.; Dunham, G. S.; Jones, M. C.; Lake, P. W.; Nielsen, D. S.; Wu, M.; Carlson, A. L.; Kernahan, M. D.; Ball, C. R.; Scharberg, R. D.; Mulville, T. D.; Breden, E. W.; Speas, C. S.; Olivas, G.; Sullivan, M. A.; York, A. J.; Justus, D. W.; Cisneros, J. C.; Strizic, T.; Reneker, J.; Cleveland, M.; Vigil, M. P.; Robertson, G.; Sandoval, D.; Cox, C.; Maurer, A. J.; Graham, D. A.; Huynh, N. B.; Toledo, S.; Molina, L. P.; Lopez, M. R.; Long, F. W.; McKee, G. R.; Porter, J. L.; Herrmann, M. C.

    2014-05-01

    Imploding wire arrays on the 20 MA Z generator have recently provided some of the most powerful and energetic laboratory sources of multi-keV photons, including ˜375 kJ of Al K-shell emission (h? ˜ 1-2 keV), ˜80 kJ of stainless steel K-shell emission (h? ˜ 5-9 keV) and a kJ-level of Mo K-shell emission (h? ˜ 17 keV). While the global implosion dynamics of these different wire arrays are very similar, the physical process that dominates the emission from these x-ray sources fall into three broad categories. Al wire arrays produce a column of plasma with densities up to ˜3 × 1021 ions/cm3, where opacity inhibits the escape of K-shell photons. Significant structure from instabilities can reduce the density and increase the surface area, therefore increase the K-shell emission. In contrast, stainless steel wire arrays operate in a regime where achieving a high pinch temperature (achieved by thermalizing a high implosion kinetic energy) is critical and, while opacity is present, it has less impact on the pinch emissivity. At higher photon energies, line emission associated with inner shell ionization due to energetic electrons becomes important.

  2. Design and fabrication of supermirrors for (2-10 keV) high resolution X-ray plasmas diagnostic imaging

    NASA Astrophysics Data System (ADS)

    Maury, H.; Bridou, F.; Troussel, Ph.; Meltchakov, E.; Delmotte, F.

    2010-09-01

    We have developed non-periodic W/SiC multilayer mirrors ("supermirrors") specifically designed to reflect photons between 2 and 10 keV. The mirrors were designed and optimized with a homemade calculation code. The supermirrors are designed to work at a nominal 0.7° grazing incidence with reflectivity above 35% in almost the entire energy range. The multilayers have been deposited by magnetron sputtering. Grazing incidence X-ray reflectance at 8 keV (0.154 nm) was made using a laboratory source. Reflectance measurement over the whole range was made at Physikalisch-Technische Bundesanstalt laboratory (PTB), the synchrotron radiation facility BESSY II, in Berlin. In addition to X-ray reflectance, multilayer thickness, refractive indices and roughness were characterized. The experimental results show good agreement with theoretical computations.

  3. X-ray observations between 10 and 150 keV from the Alcator-C tokamak

    NASA Astrophysics Data System (ADS)

    Rice, J. E.; Chamberlain, K. L.

    1988-08-01

    A mercuric iodide (HgI2) detector has been used to obtain x-ray spectra in the energy range from 5 to 200 keV from the Alcator-C tokamak. During high-density Ohmic operation of Alcator-C, this detection system provides a reliable electron-temperature diagnostic. Nonthermal x-ray spectra above 20 keV are observed under certain conditions when a substantial amount of lower-hybrid rf (LHRF) power is injected. The magnitude of this nonthermal behavior strongly increases as the electron density is lowered and is more pronounced in deuterium plasmas than in hydrogen. Model electron distribution functions, which can give rise to the observed x-ray spectra, are discussed.

  4. Excess astrophysical photons from a 0.1-1 keV cosmic axion background.

    PubMed

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

    Primordial decays of string theory moduli at z~10(12) naturally generate a dark radiation cosmic axion background with 0.1-1 keV energies. This cosmic axion background can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses in the extreme ultraviolet and soft x-ray bands. Substantial and observable luminosities may be generated even for axion-photon couplings <10(-11) GeV(-1). We propose that axion-photon conversion may explain the observed excess emission of soft x rays from galaxy clusters, and may also contribute to the diffuse unresolved cosmic x-ray background. We list a number of correlated predictions of the scenario. PMID:24160588

  5. CO2 synthesis in solid CO by Lyman-? photons and 200 keV protons

    NASA Astrophysics Data System (ADS)

    Loeffler, M. J.; Baratta, G. A.; Palumbo, M. E.; Strazzulla, G.; Baragiola, R. A.

    2005-05-01

    We have studied the synthesis of carbon dioxide from solid carbon monoxide at 16 K induced by photolysis with Lyman-? photons and by irradiation with 200 keV protons to quantitatively compare the effects of photolysis and ion irradiation on CO ice and to determine the importance of these processes in interstellar ice grains. The CO and CO{2} concentrations during irradiation of an initially pure CO film evolve with fluence to a saturation value, a behaviour that is explained by a two-state model. Our results indicate that the initial CO{2} production rates for both radiation processes are similar when normalized to the absorbed energy and that the solid CO{2} abundance observed in the interstellar ices cannot be explained only by radiolysis and photolysis of pure solid CO.

  6. Solution of controversy over 1583-keV levels in sup 204 Pb

    SciTech Connect

    Trzaska, W.H.; Julin, R.; Kantele, J.; Kumpulainen, J. (Department of Physics, University of Jyvaskyla, SF-40100 Jyvaskyla, Finland (FI))

    1989-09-01

    Data from {sup 204}Pb({ital p},{ital p}{prime}){sup 204}Pb conversion-electron and gamma-ray experiments, together with previous results, prove the existence of two levels (0{sup +} and 2{sup +}) at 1583-keV excitation energy in {sup 204}Pb. Modified values (limits) of the {rho}{sub 21}{sup 2} and {ital X}{sub 211} are 0.0013{lt}{rho}{sub 21}{sup 2}{lt}0.015 and {ital X}{sub 211}{gt}0.073. New experimental evidence indicates that all the three observed excited {ital O}{sup +} states in {sup 204}Pb can be explained as belonging to the four-neutron-hole valence space and, therefore, there is no clear candidate for the proton 2p-2h intruder state in this nucleus.

  7. A 75-keV, 145-mA proton injector

    SciTech Connect

    Figueroa, T. L. (Terry L.); Hansborough, L. D. (Lash D.); Kerstiens, D. M. (Debora M.); Schneider, J. D. (J. David); Smith, H. V. (Horace V.); Stettler, M. W. (Matthew W.); Thuot, M. E. (Michael E.); Warren, D. S. (David S.); Zaugg, T. J. (Thomas J.); Arvin, A. A. (Adrian A.); Bolt, A. S.; Sherman, Joseph D.

    2001-01-01

    A dc and pulsed-mode 75-keV proton injector has been developed and is used in characterization of a continuous-wave (cw) 6.7-MeV, 100-mA radio-frequency quadrupole (RFQ). The injector is used frequently at the full RFQ design power (100-mA, 6.7-MeV) where the RFQ admittance (1rms, normalized) is 0.23 ({pi}mm-mrad). The injector includes a 2.45-GHz microwave proton source and a beam space-charge-neutralized, two magnetic-solenoid, low-energy beam-transport system (LEBT). The design RFQ beam transmission of 95% has been demonstrated at 100-mA RFQ output current.

  8. Irradiation of water ices by 2 keV carbon ions

    NASA Astrophysics Data System (ADS)

    Hunniford, C. A.; Dawes, A.; Fulvio, D.; Sivaraman, B.; Merrigan, T. L.; McCullough, R. W.; Mason, N. J.; Palumbo, M. E.

    2009-04-01

    In this paper, we report on the results of experimental studies of the irradiation of pure water ices using 2 keV 13C+ and 13C2+ ions. Studies have been carried out at two temperatures (30 and 90 K) and the influence of the different morphologies at these temperatures has also been studied. With singly charged ions, the formation of 13CO2 was observed to be a strongly dependent upon morphology and showed a weaker dependence upon temperature. With doubly charged ions, the dependence upon temperature was significantly stronger. This is explained by enhanced production of reactive species resulting from the additional potential energy contained within the doubly charged ions. Increased temperature provides mobility to these species which may then yield additional 13CO2.

  9. Preliminary resolved resonance region evaluation of copper-63 from 0 to 300 keV

    SciTech Connect

    Sobes, V.; Forget, B. [Dept. of Nuclear Science and Engineering, Massachusetts Inst. of Technology, Bldg. 24, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Leal, L.; Guber, K. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States)

    2012-07-01

    A new preliminary evaluation of Cu-63 was done in the energy region from 0 to 300 keV extending the resolved resonance region of the previous, ENDF/B-VII.0, evaluation three-fold. The new evaluation was based on three experimental transmission data sets; two measured at the Oak Ridge Electron Linear Accelerator (ORELA) and one from the Massachusetts Inst. of Technology Nuclear Reactor (MITR). A total of 275 new resonances were identified and a corresponding set of external resonances was approximated to mock up the external levels. The negative external levels (bound level) were modified to match the thermal cross section values. A preliminary benchmarking calculation was made using 11 ICSBEP benchmarks. This work is in support of the DOE Nuclear Criticality Safety Program. (authors)

  10. Measurements of total atomic attenuation cross sections of Tm, Yb, Lu, Hf, Ta, W, Re and Os Elements at 122keV and 136keV

    SciTech Connect

    Kaya, N.; Tirasoglu, E.; Apaydin, G.; Kobya, A. I. [Karadeniz Technical University, Faculty of Arts and Sciences, Department of Physics, Trabzon, 61080 (Turkey)

    2007-04-23

    The aim of this study was to measure the total atomic attenuation cross sections ({sigma}t) in eighth elements (69{<=}Z{<=}76) at 122 keV and 136 keV. The experimental values of the cross sections were determined using the transmission geometry. Measurements have been performed using an annular source (Co-57) and Ultra-LEGe solid state detector with a resolution of 150 eV at 5.9 keV. Experimental results have been compared with theoretically calculated values and other available experimental results. Good agreement was observed among the experimental, theoretical and other experimental values.

  11. A Hard Medium Survey with the ASCA GIS: the (2-10 keV) Number Counts Relationship

    E-print Network

    Ilaria Cagnoni; Roberto Della Ceca; Tommaso Maccacaro

    1997-09-02

    In this paper we report the first results on a medium survey program conducted in the 2-10 keV energy band using data from the GIS2 instrument onboard the ASCA satellite. We have selected from the ASCA public archive (as of February 14, 1996) 87 images which are suitable for this project. 60 serendipitous X-ray sources, with a snr greater than 3.5, were found. The 2-10 keV flux of the detected sources ranges from 1.1e-13 erg/cm2/s to 4.1e-12 erg/cm2/s. Using this sample we have extended the description of the 2-10 keV LogN(>S)-LogS to a flux limit of ~6.3e-14 erg/cm2/s (the faintest detectable flux), i.e. about 2.7 orders of magnitude fainter than the Piccinotti et al. (1982) determination. The derived number-flux relationship is well described by a power law model, N(>S) = K S^{-a}, with best fit values a = 1.67 +- 0.18 and K = 2.85e-21 1/deg2. At the flux limit of the survey about 27% of the Cosmic X-ray Background in the 2-10 keV energy band is resolved in discrete sources. A flattening of the number-flux relationship, within a factor of 10 from the flux limit of the present survey, is expected in order to avoid saturation. The implications of these results on the models for the origin of the hard X-ray background are briefly discussed.

  12. Beam position monitor R&D for keV ion beams

    E-print Network

    Naveed, S; Nosych, A; Søby,L

    2013-01-01

    Beams of cooled antiprotons at keV energies shall be provided by the Ultra-low energy Storage Ring (USR) at the Facility for Low energy Antiproton and Ion Research (FLAIR) and the Extra Low ENergy Antiproton ring (ELENA) at CERN's Antiproton Decelerator (AD) facility. Both storage rings put challenging demands on the beam position monitoring (BPM) system as their capacitive pick-ups should be capable of determining the beam position of beams at low intensities and low velocities, close to the noise level of state-of-the-art electronics. In this contribution we describe the design and anticipated performance of BPMs for low-energy ion beams with a focus on the ELENA orbit measurement systems. We also present the particular challenges encountered in the numerical simulation of pickup response at very low beta values. Finally, we provide an outlook on how the implementation of faster algorithms for the simulation of BPM characteristics could potentially help speed up such studies considerably.

  13. Calculations of stopping powers of 100 eV-30 keV electrons in 31 elemental solids

    NASA Astrophysics Data System (ADS)

    Tanuma, S.; Powell, C. J.; Penn, D. R.

    2008-03-01

    We present calculated electron stopping powers (SPs) for 31 elemental solids (Li, Be, glassy C, graphite, diamond, Na, Mg, K, Sc, Ti, V, Fe, Y, Zr, Nb, Mo, Ru, Rh, In, Sn, Cs, Gd, Tb, Dy, Hf, Ta, W, Re, Os, Ir, and Bi). These SPs were determined with an algorithm previously used for the calculation of electron inelastic mean free paths and from energy-loss functions (ELFs) derived from experimental optical data. The SP calculations were made for electron energies between 100eV and 30keV and supplement our earlier SP calculations for ten additional solids (Al, Si, Cr, Ni, Cu, Ge, Pd, Ag, Pt, and Au). Plots of SP versus atomic number for the group of 41 solids show clear trends. Multiple peaks and shoulders are seen that result from the contributions of valence-electron and various inner-shell excitations. Satisfactory agreement was found between the calculated SPs and values from the relativistic Bethe SP equation with recommended values of the mean excitation energy (MEE) for energies above 10keV. We determined effective MEEs versus maximum excitation energy from the ELFs for each solid. Plots of effective MEE versus atomic number showed the relative contributions of valence-electron and different core-electron excitations to the MEE. For a maximum excitation energy of 30keV, our effective MEEs agreed well for Be, graphite, Na, Al, and Si with recommended MEEs; a difference for Li was attributed to sample oxidation in the SP measurements for the recommended MEE. Substantially different effective MEEs were found for the three carbon allotropes (graphite, diamond, and glassy C).

  14. Resolved resonance parameters for /sup 238/U from 4 to 6 keV

    SciTech Connect

    Olsen, D.K.; Meszaros, P.S.

    1983-01-01

    Neutron widths for 145 resonances from 4 to 6 keV are reported from a least-squares shape analysis of the Oak Ridge Electron Linear Accelerator 150-m flight path, four-sample /sup 238/U transmission data. The resultant s-wave strength function from 4 to 6 keV is found to be substantially smaller than that from 0 to 4 keV.

  15. Observations of 35- 10 1600-keV protons and low-frequency waves upstream of interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Sanderson, T. R.; Reinhard, R.; Van Nes, P.; Wenzel, K.-P.; Smith, E. J.; Tsurutani, B. T.

    1985-01-01

    The present investigation is concerned with a comparison of measurements of energetic protons in the range from 35 to 1600 keV and low-frequency waves (periods of approximately 6 s) on ISEE 3 associated with the passage of the large oblique shock of April 5, 1979, which exhibits an extended foreshock. An attempt is made to identify the energy of the particles which are responsible for the waves. Intensity profiles of both waves and particles as a function of upstream distance are compared, taking into account the relation between the energy of the particles and the period of the waves. The considered approach makes it possible to identify protons with energies of a few hundred keV as being responsible for the waves in the extended foreshock. It is believed that the high energy density of the high-energy solar flare protons preceding the shock could be responsible for 'seed' waves which provide the scattering centers necessary for the acceleration of the lower-energy protons via a first-order Fermi mechanism.

  16. Effects of 50 keV and 100 keV Proton Irradiation on GaInP\\/GaAs\\/Ge Triple-Junction Solar Cells

    Microsoft Academic Search

    Wang Rong; Feng Zhao; Liu Yunhong; Lu Ming

    2012-01-01

    GaInP\\/GaAs\\/Ge triple-junction solar cells were irradiated with 50 keV and 100 keV protons at fluences of 5 × 1010 cm?2, 1 × 1011 cm?2, 1 × 1012 cm?2, and 1 × 1013 cm?2. Their performance degradation is analyzed using current-voltage characteristics and spectral response measurements, and then the changes in Isc, Voc, Pmax and the spectral response of the cells

  17. ON THE SPECTRAL HARDENING AT {approx}>300 keV IN SOLAR FLARES

    SciTech Connect

    Li, G.; Kong, X.; Zank, G. [Department of Physics and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Chen, Y., E-mail: gang.li@uah.edu [Institute of Space Sciences and School of Space Sciences and Physics, Shandong University, 264209 Weihai (China)

    2013-05-20

    It has long been noted that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies {approx}>300 keV. It is now widely believed that at least in electron-dominated events, the hardening in the photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power-law spectrum of electrons with a hardening at high energies can be explained by the diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady-state transport equation at a shock with a tanh profile was solved for a p-independent diffusion coefficient. Numerical simulations with a p-dependent diffusion coefficient show hardenings in the accelerated electron spectrum that are comparable with observations. One necessary condition for our proposed scenario to work is that high-energy electrons resonate with the inertial range of the MHD turbulence and low-energy electrons resonate with the dissipation range of the MHD turbulence at the acceleration site, and the spectrum of the dissipation range {approx}k {sup -2.7}. A {approx}k {sup -2.7} dissipation range spectrum is consistent with recent solar wind observations.

  18. Quantum Efficiency Calibration of AXAF CCDs from 2 10 keV Herbert L. Manning, Stephen E. Jones, Steve E. Kissel,

    E-print Network

    the CCDs, providing a range of discrete emission lines to cover the energy band. A Si(Li) solid state.1­10 keV band. The MIT Center for Space Research, together with the MIT Lincoln Laboratory scientific focal plane instruments. 2 To unfold accurately the X­ray spectra of astrophysical sources

  19. Capture of a neutron to excited states of a {sup 9}Be nucleus taking into account resonance at 622 keV

    SciTech Connect

    Dubovichenko, S. B., E-mail: dubovichenko@gmail.com [National Space Agency of the Republic of Kazakhstan, Fessenkov Astrophysical Institute, National Space Research and Technologies Center (Kazakhstan)

    2013-10-15

    Radiative capture of a neutron to the ground and excited states of the 9Be nucleus is considered using the potential cluster model with forbidden states and with classification of cluster states by the Young schemes taking into account resonance at 622 keV for thermal and astrophysical energies.

  20. MISE AU POINT D'UN DTECTEUR D'ATOMES D'HYDROGNE D'NERGIE COMPRISE ENTRE 10 keV ET 30 eV

    E-print Network

    Paris-Sud XI, Université de

    . 2014 For a given energy, between 10 keV and 30 eV, the secondary-electron yields on copper-beryllium alloys used in electron multipliers are equal for H+ and H. For a beam of H atoms obtained by charge

  1. Interaction Potential between He+ and Ti in a keV Range as Revealed by a Specialized Technique in Ion Scattering Spectroscopy

    Microsoft Academic Search

    Masakazu Aono; Yinchun Hou; Ryutaro Souda; Chuhei Oshima; Shigeki Otani; Yoshio Ishizawa; Kyoji Matsuda; Ryuichi Shimizu

    1982-01-01

    The interaction potential between He+ and Ti in a keV range has been studied by a specialized technique in low-energy ion scattering spectroscopy. The interaction potential is described well by the Thomas-Fermi-Molière potential for the interaction between neutral He and Ti with a scaled screening radius.

  2. Sub-arcsec X-Ray Telescope for Imaging The Solar Corona In the 0.25 - 1.2 keV Band

    NASA Technical Reports Server (NTRS)

    Gallagher, Dennis; Cash, Webster; Jelsma, Schuyler; Farmer, Jason

    1996-01-01

    We have developed an X-ray telescope that uses a new technique for focusing X-rays with grazing incidence optics. The telescope was built with spherical optics for all of its components, utilizing the high quality surfaces obtainable when polishing spherical (as opposed to aspherical) optics. We tested the prototype X-ray telescope in the 300 meter vacuum pipe at White Sands Missile Range, NM. The telescope features 2 degee graze angles with tungsten coatings, yielding a bandpass of 0.25-1.5 keV with a peak effective area of 0.8 sq cm at 0.83 keV. Results from X-ray testing at energies of 0.25 keV and 0.93 keV (C-K and Cu-L) verify 0.5 arcsecond performance at 0.93 keV. Results from modeling the X-ray telescope's response to the Sun show that the current design would be capable of recording 10 half arcsecond images of a solar active region during a 300 second NASA sounding rocket flight.

  3. Strengths of the resonances at 436, 479, 639, 661, and 1279 keV in the $^{22}$Ne(p,$\\gamma$)$^{23}$Na reaction

    E-print Network

    Depalo, Rosanna; Ferraro, Federico; Slemer, Alessandra; Al-Abdullah, Tariq; Akhmadaliev, Shavkat; Anders, Michael; Bemmerer, Daniel; Elekes, Zoltán; Mattei, Giovanni; Reinicke, Stefan; Schmidt, Konrad; Scian, Carlo; Wagner, Louis

    2015-01-01

    The $^{22}$Ne(p,$\\gamma$)$^{23}$Na reaction is included in the neon-sodium cycle of hydrogen burning. A number of narrow resonances in the Gamow window dominates the thermonuclear reaction rate. Several resonance strengths are only poorly known. As a result, the $^{22}$Ne(p,$\\gamma$)$^{23}$Na thermonuclear reaction rate is the most uncertain rate of the cycle. Here, a new experimental study of the strengths of the resonances at 436, 479, 639, 661, and 1279 keV proton beam energy is reported. The data have been obtained using a tantalum target implanted with $^{22}$Ne. The strengths $\\omega\\gamma$ of the resonances at 436, 639, and 661 keV have been determined with a relative approach, using the 479 and 1279 keV resonances for normalization. Subsequently, the ratio of resonance strengths of the 479 and 1279 keV resonances was determined, improving the precision of these two standards. The new data are consistent with, but more precise than, the literature with the exception of the resonance at 661 keV, which i...

  4. 3.5 keV X-ray line from nearly-degenerate WIMP dark matter decays

    NASA Astrophysics Data System (ADS)

    Chiang, Cheng-Wei; Yamada, Toshifumi

    2014-09-01

    The unidentified emission line at the energy of ~3.5 keV observed in X-rays from galaxy clusters may originate from a process involving a dark matter particle. On the other hand, a weakly interacting massive particle (WIMP) has been an attractive dark matter candidate, due to its well-understood thermal production mechanism and its connection to physics at the TeV scale. In this paper, we pursue the possibility that the 3.5 keV X-ray arises from a late time decay of a WIMP dark matter into another WIMP dark matter, both of which have the mass of O(100) GeV and whose mass splitting is about 3.5 keV. We focus on the simplest case where there are two Majorana dark matter particles and two charged scalars that couple with a standard model matter particle. By assuming a hierarchical structure in the couplings of the two dark matter particles and two charged scalars, it is possible to explain the 3.5 keV line and realize the WIMP dark matter scenario at the same time. Since the effective coupling of the two different Majorana dark matter particles and one photon violates CP symmetry, the model always contains a new source of CP violation, so the model's connection to the physics of electric dipole moments is discussed. The model's peculiar signatures at the LHC are also studied. We show the prospect of detecting the charged scalars through a detailed collider simulation.

  5. Study of 1–8 keV K-? x-ray emission from high intensity femtosecond laser produced plasma

    SciTech Connect

    Arora, V., E-mail: arora@rrcat.gov.in; Naik, P. A.; Chakera, J. A.; Bagchi, S.; Tayyab, M.; Gupta, P. D. [Laser Plasma Division, Raja Rammana Centre for Advanced Technology, Indore 452 013 (India)] [Laser Plasma Division, Raja Rammana Centre for Advanced Technology, Indore 452 013 (India)

    2014-04-15

    We report an experimental study on the optimization of a laser plasma based x-ray source of ultra-short duration K-? line radiation. The interaction of pulses from a CPA based Ti:sapphire laser (10 TW, 45 fs, 10 Hz) system with magnesium, titanium, iron and copper solid target generates bright 1-8 keV K-? x-ray radiation. The x-ray yield was optimized with the laser pulse duration (at fixed fluence) which is varied in the range of 45 fs to 1.4 ps. It showed a maximum at laser pulse duration of ?740 fs, 420 fs, 350 and 250 fs for Mg (1.3 keV), Ti (4.5 keV), Fe (6.4 keV) and Cu (8.05 keV) respectively. The x-ray yield is observed to be independent of the sign of the chirp. The scaling of the K-? yield (I{sub x} ? I{sub L}{sup ?}) for 45 fs and optimized pulse duration were measured for laser intensities in the region of 3 × 10{sup 14} – 8 × 10{sup 17}. The x-ray yield shows a much faster scaling exponent ? = 1.5, 2.1, 2.4 and 2.6 for Mg, Ti, Fe and Cu respectively at optimized pulse duration compared to scaling exponent of 0.65, 1.3, 1.5, and 1.7 obtained for 45 fs duration laser pulses. The laser to x-ray energy conversion efficiencies obtained for different target materials are ?{sub Mg} = 1.2 × 10{sup ?5}, ?{sub Ti} = 3.1 × 10{sup ?5}, ?{sub Fe} = 2.7 × 10{sup ?5}, ?{sub Cu} = 1.9 × 10{sup ?5}. The results have been explained from the efficient generation of optimal energy hot electrons at longer laser pulse duration. The faster scaling observed at optimal pulse duration indicates that the x-ray source is generated at the target surface and saturation of x-ray emission would appear at larger laser fluence. An example of utilization of the source for measurement of shock-wave profiles in a silicon crystal by time resolved x-ray diffraction is also presented.

  6. K X-ray production cross sections in aluminium for 15, 20 and 25 keV protons

    NASA Astrophysics Data System (ADS)

    do Carmo, S. J. C.; Borges, F. I. G. M.; Trindade, A. M. F.; Conde, C. A. N.

    2012-12-01

    A low-energy particle accelerator has been used to determine experimentally low-energy X-ray production cross sections through the irradiation of thick targets with ions with energies up to 25 keV/ion charge by measuring thick target yields. We obtained aluminium K- X-ray production cross sections values of 8.4 × 10-4, 1.3 × 10-3 and 1.8 × 10-3 barn for 15, 20 and 25 keV protons, respectively. Although there are no results in the literature for such low-energy impinging protons for comparison, the results presented here are in good agreement with the general trend exhibited for higher energy ranges.

  7. Characterizations of MCP performance in the hard x-ray range (6–25 keV)

    SciTech Connect

    Wu, Ming, E-mail: minwu@sandia.gov; Rochau, Greg [Sandia National Laboratory, Albuquerque, New Mexico 87185 (United States); Moy, Ken [Special Technology Laboratories, NSTec, Santa Barbara, California 93111-2335 (United States); Kruschwitz, Craig [National Security Technologies, LLC, Los Alamos Operations, Los Alamos, New Mexico 87544 (United States)

    2014-11-15

    MCP detector performance at hard x-ray energies from 6 to 25 keV was recently investigated using NSLS beamline X15A at BNL. Measurements were made with an NSTec Gen-II (H-CA-65) framing camera, based on a Photonis MCP with ?10 ?m in diameter pores, ?12 ?m center-center spacing, an L/D ratio of 46, and a bias angle of 8°. The MCP characterizations were focused on (1) energy and angle dependent sensitivity, (2) energy and angle dependent spatial resolution, (3) energy dependent gain performance, and (4) energy dependent dynamic range. These measurement corroborated simulation results using a Monte Carlo model that included hard x-ray interactions and the subsequent electron cascade in the MCP.

  8. ART: Surveying the Local Universe at 2-11 keV

    NASA Technical Reports Server (NTRS)

    O'Dell, S. L.; Ramsey, B. D.; Adams, M. L.; Brandt, W. N.; Bubarev, M. V.; Hassinger, G.; Pravlinski, M.; Predehl, P.; Romaine, S. E.; Swartz, D. A.; Urry, C. M.; Vikhlinin, A.; Weisskopf, M. C.

    2008-01-01

    The Astronomical Rontgen Telescope (ART) is a medium-energy x-ray telescope system proposed for the Russian-led mission Spectrum Rontgen-Gamma (SRG). Optimized for performance over the 2-11-keV band, ART complements the softer response of the SRG prime instrument-the German eROSITA x-ray telescope system. The anticipated number of ART detections is 50,000-with 1,000 heavily-obscured (N(sub H)> 3x10(exp 23)/sq cm) AGN-in the SRG 4-year all-sky survey, plus a comparable number in deeper wide-field (500 deg(sup 2) total) surveys. ART's surveys will provide a minimally-biased, nearly-complete census of the local Universe in the medium-energy x-ray band (including Fe-K lines), at CCD spectral resolution. During long (approx.100-ks) pointed observations, ART can obtain statistically significant spectral data up to about 15 keY for bright sources and medium-energy x-ray continuum and Fe-K-line spectra of AGN detected with the contemporaneous NuSTAR hard-x-ray mission.

  9. Do the O2 Schumann-Runge bands participate in keV collision-induced dissociation experiments?

    PubMed

    Lin, Yawei; Mayer, Paul M

    2011-01-01

    In high-energy (keV) CID experiments, oxygen has the unique ability to enhance specific ion fragmentation pathways that lie within a relatively narrow band of activation energy. It has been previously proposed that this oxygen-enhanced dissociation phenomenon is due to the participation of the O(2) B(3)?(u)(+) - X(3)?(g)(-) (Schumann-Runge) system in the collision complex. During the collision, oxygen is first excited to its [Formula: see text] state before it returns this energy to the projectile ion. This energy drives the nonstatistical dissociation of the projectile provided there is an energetically accessible pathway in resonance with the absorbed radiation. To probe the validity of this hypothesis, a modified VG-ZAB mass spectrometer was used to observe the photon emissions from keV collisions of a selection of projectile ions with O(2) target gas. By studying the resulting collision-induced emission (CIE) spectra, a second potential mechanism came to light, one that involves the near-isoenergetic O(2) (+.) A (2)?(u)?X (2) ?(g) state transition. PMID:21472546

  10. Atomic, Molecular, and Optical Physics: Optical Excitation Function of H(1s-2p) Produced by electron Impact from Threshold to 1.8 keV

    NASA Technical Reports Server (NTRS)

    James, G. K.; Slevin, J. A.; Shemansky, D. E.; McConkey, J. W.; Bray, I.; Dziczek, D.; Kanik, I.; Ajello, J. M.

    1997-01-01

    The optical excitation function of prompt Lyman-Alpha radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet mono- chromator system was used to measure the emitted Lyman-Alpha radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Statistical and known systematic uncertainties in our data range from +/- 4% near threshold to +/- 2% at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close- coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10% level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7% of the CCC calculations over the 14 eV-1.8 keV range. The present CCC calculations converge on the Bethe- Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3% is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV - 1.8 keV energy range.

  11. Comparison between an event-by-event Monte Carlo code, NOREC, and ETRAN for electron scaled point kernels between 20 keV and 1 MeV.

    PubMed

    Cho, Sang Hyun; Vassiliev, Oleg N; Horton, John L

    2007-03-01

    An event-by-event Monte Carlo code called NOREC, a substantially improved version of the Oak Ridge electron transport code (OREC), was released in 2003, after a number of modifications to OREC. In spite of some earlier work, the characteristics of the code have not been clearly shown so far, especially for a wide range of electron energies. Therefore, NOREC was used in this study to generate one of the popular dosimetric quantities, the scaled point kernel, for a number of electron energies between 0.02 and 1.0 MeV. Calculated kernels were compared with the most well-known published kernels based on a condensed history Monte Carlo code, ETRAN, to show not only general agreement between the codes for the electron energy range considered but also possible differences between an event-by-event code and a condensed history code. There was general agreement between the kernels within about 5% up to 0.7 r/r (0) for 100 keV and 1 MeV electrons. Note that r/r (0) denotes the scaled distance, where r is the radial distance from the source to the dose point and r (0) is the continuous slowing down approximation (CSDA) range of a mono-energetic electron. For the same range of scaled distances, the discrepancies for 20 and 500 keV electrons were up to 6 and 12%, respectively. Especially, there was more pronounced disagreement for 500 keV electrons than for 20 keV electrons. The degree of disagreement for 500 keV electrons decreased when NOREC results were compared with published EGS4/PRESTA results, producing similar agreement to other electron energies. PMID:17219152

  12. Studies of MCP Sensitivity to 250 eV to 25 keV x-rays: Comparisons of Monte Carlo Simulations and Experimental Results

    NASA Astrophysics Data System (ADS)

    Wu, Ming; Kruschwitz, Craig; Moy, Ken; Rochau, Greg; Sandia National Laboratories Team; National Security Technologies, Inc. Team

    2014-10-01

    We present results of Monte Carlo simulations of microchannel plate (MCP) response to x-rays in the 250 eV to 25 keV energy range as a function of x-ray energy, impact angle, and x-ray flux. X-ray penetration through multiple MCP pore walls is increasingly important above 5 keV and the effect of this penetration on MCP performance is studied. In agreement with past measurements, it is found that the angular dependence of MCP sensitivity with angle changes from a cotangent dependence to angular independence as x-ray energy increases. It is also found that the MCP gain sensitivity with voltage decreases for higher x-ray energies. Finally, it is found that for x-rays incident at zero degrees relative to the MCP surface normal, spatial resolution shows little dependence on x-ray energy, but that spatial resolution degrades for higher x-ray energies as the angle of incidence relative to the surface normal increases. Dynamic range of MCP in this energy range is also examined. Simulation results are compared to recent experimental measurements for 6-25 keV x-rays. The experiments were performed on the X15 beamline at the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. Agreement between simulations and experiments is generally very good.

  13. One-dimensional x-ray imaging using a spherically bent mica crystal at 4.75 keV

    SciTech Connect

    Workman, J.; Evans, S.; Kyrala, G. A.

    2001-01-01

    One-dimensional x-ray imaging of static gold bars using a spherically bent mica crystal is presented for the first time at an x-ray energy of 4.75 keV. X rays are produced using 1-ns-square pulses on the TRIDENT laser facility driving the He-like resonance transition in solid titanium disks. Time-integrated images of square profile parallel gold bars are recorded on direct exposure film with a magnification of {approx}10. Rising edge measurements of the bars demonstrate resolutions of about 6--7 {mu}m over a 400 {mu}m field of view.

  14. Auger electron emission from a Si(1 1 1) surface during 11-keV Ar+ ion sputtering

    NASA Astrophysics Data System (ADS)

    Kawai, K.; Sakuma, Y.; Kato, M.; Soda, K.

    2013-11-01

    Ion sputtering experiments were carried out for a Si(1 1 1)-7 × 7 surface, irradiated with an 11-keV Ar+ beam. The energy spectra of secondary electrons were measured with a cylindrical mirror analyzer (CMA). The dependence of the Auger electron yield on the ion incidence angle, ?, measured from the surface normal, was studied by varying ? from 0° to 80°. The Auger electron yield increases with increasing incidence angle. This angular dependence is similar to that of the Si sputtering yield. Both angular dependences could be reasonably understood in terms of ion range, escape depths of the sputtered ion and the electron mean free path.

  15. Neutron scattering measurements in {sup 197}Au from 850 keV to 2.0 MeV

    SciTech Connect

    O`Connor, M.; Chen, J.; Egan, J.J. [and others

    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.

  16. Silicon photodiode characterization from 1 eV to 10 keV

    NASA Astrophysics Data System (ADS)

    Idzorek, George C.; Bartlett, R. J.

    1997-10-01

    Silicon photodiodes offer a number of advantages over conventional photocathode type soft x-ray detectors in pulsed power experiments. These include a nominally flat response, insensitivity to surface contamination, low voltage biasing requirements, sensitivity to low energy photons, excellent detector to detector response reproducibility, and ability to operate in poor vacuum or gas backfilled experiments. Silicon photodiodes available from International Radiation Detectors (IRD), Torrance, California have been characterized for absolute photon response from 1 eV to 10 keV photon energy, time response, and signal saturation levels. We have assembled individually filtered photodiodes into an array designated the XUV-7. The XUV-7 provides seven photodiodes in a vacuum leak tight, electrically isolated, low noise, high bandwidth, x-ray filtered assembly in a compact package with a 3.7 cm outside diameter. In addition we have assembled the diodes in other custom configurations as detectors for spectrometers. Our calibration measurements show factor of ten deviations from the silicon photodiode theoretical flat response due to diode sensitivity outside the center 'sensitive area.' Detector response reproducibility between diodes appears to be better than 5%. Time response measurements show a 10 - 90% rise time of about 0.1 nanoseconds and a fall time of about 0.5 nanoseconds. Silicon photodiodes have proven to be a versatile and useful complement to our standard photocathode detectors for soft x-ray measurement and are very competitive with diamond for a number of applications.

  17. Absolute ionization yield of 6.7 keV argon nuclear recoils in liquid argon

    NASA Astrophysics Data System (ADS)

    Sorensen, Peter

    2014-09-01

    We have made a first measurement of the total electronic energy loss of low-energy argon atoms stopping in liquid argon. The importance of the measurement is underscored by the fact that state of the art theoretical treatment of this problem is only approximate. While these results are of modest interest to condensed matter theory, they are of keen interest to experiments seeking to directly detect signals due to nuclear recoils. Two particular interactions which would result in nuclear recoil signals are the scattering of hypothetical dark matter particles, or coherent elastic neutrino nucleus scattering. Using quasi mono-energetic neutrons from a collimated and filtered 7Li(p,n) source, we measured the absolute ionization yield of nuclear recoils in liquid argon at 6.7 keV at applied electric fields ranging from 200--2130 V/cm. We will discuss the experimental setup used for these measurements, our findings and their implications, and finally our recent efforts to apply this technique to liquid xenon.

  18. Experimental Study of the 91Zr(n,gamma) Reaction Up to 26 keV

    SciTech Connect

    Tagliente, G. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Koehler, Paul Edward [ORNL

    2009-01-01

    The neutron capture cross sections of the Zr isotopes are relevant to studies in nuclear structure, nuclear astrophysics, and nuclear technology. The valence neutron of {sup 91}Zr with respect to the neutron magic nucleus {sup 90}Zr has interesting implications for the statistical analysis in the proximity of shell closures. In stellar nucleosynthesis, the Zr isotopes are important for the s-process reaction flow between the Fe seeds and the heavier isotopes. Because of its relatively small (n,{gamma}) cross sections, Zr represents also an interesting structural material for nuclear reactors. For the same reason, these cross sections are difficult to measure and reliable data are sparse. Therefore, the (n,{gamma}) cross sections of the Zr isotopes have been remeasured at the CERN n{_}TOF facility. Thanks to its high instantaneous flux, good energy resolution, and low background, this facility is particularly suited for the determination of small, resonance-dominated cross sections. In this work, results for the {sup 91}Zr(n,){sup 92}Zr reaction are reported in the neutron energy range from thermal to 26 keV. In this region, accurate data of 157 resonances could be obtained, 33 of these resonances are not present in the main databases and/or were observed for the first time.

  19. LUCIA - a new 1-7 keV {mu}-XAS Beamline

    SciTech Connect

    Janousch, M.; Schmidt, Th.; Wetter, R.; Grolimund, G.; Scheidegger, A.M. [Paul Scherrer Institute (PSI), CH-5232 Villigen PSI (Switzerland); Flank, A.-M.; Lagarde, P.; Cauchon, G.; Bac, S. [LURE, Bat 209d, Centre Universitaire Paris-Sud, BP 34, 91898 Orsay Cedex (France); Dubuisson, J.M. [Synchrotron SOLEIL, L'Orme de Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France)

    2004-05-12

    LURE-SOLEIL (France) and the Swiss Light Source (SLS) are building together a new micro focused beamline for micro x-ray absorption spectroscopy and micro imaging. This line is designed to deliver a photon flux of the order of 1012 ph/sec on a 1 x 1 {mu}m spot within the energy domain of 0.8 to 7 keV. This beam line is being installed on the X07M straight section of SLS. The source is an APPLE II undulator with a period of 54 mm. The main advantage of this device lies in the delivery of any degree of polarization, linear or circular, over the whole energy range, without the need of a sample-position change. The monochromator will be a fixed exit double crystal equipped with 5 sets of crystals, thanks to the very narrow photon beam from the undulator ( Beryl, KTP, YB66, InSb(111), Si(111) ). The optics includes a first horizontal focusing mirror (spherical), which produces an intermediate source for the horizontal mirror of a Kirkpatrick-Baez (KB) system. The vertical mirror of the KB directly images the source. Finally, a low-pass double mirror filter insures a proper harmonic rejection.

  20. A simple approach to determine the radioactivities of nuclides with 200–2000 keV ? ray(s) in the absence of efficiency calibration standard

    Microsoft Academic Search

    Xiao-Gui Feng; Qian-Ge He; Zhong-Gong Chen; Xue-Mei Han; Jian-Feng Guo

    2011-01-01

    By combing 4? liquid scintillation (LS) and ? spectrometry, we proposed a new approach, which is based on the linearity of the energy and the efficiency of coaxial HPGe detectors in logarithmic coordinates, to determine the radioactivities of nuclides with 200–2000 keV ? ray(s). In this approach, the multi-gamma-ray nuclide 152Eu has been applied to obtain the slope of energy-efficiency line.

  1. Enhancement of the 6.4 keV Line in the Inner Galactic Ridge: Proton-induced Fluorescence?

    NASA Astrophysics Data System (ADS)

    Nobukawa, K. K.; Nobukawa, M.; Uchiyama, H.; Tsuru, T. G.; Torii, K.; Tanaka, T.; Chernyshov, D. O.; Fukui, Y.; Dogiel, V. A.; Koyama, K.

    2015-07-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A* because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with the molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with a large equivalent width of ?1.3 keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudinal distribution of the excess emission disfavors the X-ray irradiation, either by Sagittarius A* or by nearby X-ray binaries. Then, the low-energy proton bombardment is the most probable origin, although the high-energy density ?80 eV cm?3 in 0.1–1000 MeV is required and there is no conventional proton source in the vicinity.

  2. Fast neutron ineleastic scattering cross sections of /sup 238/U for states between 680 and 1530 keV

    SciTech Connect

    Shao, J.Q.; Couchell, G.P.; Egan, J.J.; Kegel, G.H.R.; Li, S.Q.; Mittler, A.; Pullen, D.J.; Schier, W.A.; Arthur, E.D.

    1986-03-01

    Neutron inelastic scattering cross sections for /sup 238/U levels between 680- and 1530-keV excitation energy have been measured in the incident neutron energy range from 0.9 to 2.2 MeV. The (n,n') time-of-flight (TOF) technique was used to obtain direct differential inelastic cross sections. Neutrons were generated using the /sup 7/Li(p,n)/sup 7/Be reaction. Experimental parameters were optimized to achieve an energy resolution of <15 keV. Level cross sections were deduced from the measured 125-deg differential scattering cross sections. The validity of this procedure was confirmed by measuring the angular distributions for nine levels at En=1.5 and 2.0 MeV. Background due to fission induced by fast neutrons was subtracted. The TOF spectra were unfolded using the method of the response function. The data were corrected for multiple scattering and neutron attenuation in disk scattering geometry using an analytic method. Theoretical calculations of the cross sections were carried out using reaction models appropriate to the description of compound nucleus and direct interaction processes. The data are compared to (n,n'..gamma..) results and the ENDF/B-V evaluation.

  3. Measurement of the ionization yield of nuclear recoils in liquid argon at 80 and 233 keV

    NASA Astrophysics Data System (ADS)

    Bondar, A.; Buzulutskov, A.; Dolgov, A.; Grishnyaev, E.; Polosatkin, S.; Shekhtman, L.; Shemyakina, E.; Sokolov, A.

    2014-10-01

    The energy calibration of nuclear recoil detectors is of primary importance to rare-event experiments such as those of direct dark matter search and coherent neutrino-nucleus scattering. In particular, such a calibration is performed by measuring the ionization yield of nuclear recoils in liquid Ar and Xe detection media, using neutron elastic scattering off nuclei. In the present work, the ionization yield for nuclear recoils in liquid Ar has for the first time been measured in the higher energy range, at 80 and 233 keV, using a two-phase Cryogenic Avalanche Detector (CRAD) and DD neutron generator. The ionization yield in liquid Ar at an electric field of 2.3 kV/cm amounted to 7.8+/-1.1 and 9.7+/-1.3 \\text{e}^-/\\text{keV} at 80 and 233 keV, respectively. The Jaffe model for nuclear recoil-induced ionization, in contrast to that of Thomas-Imel, can probably consistently describe the energy dependence of the ionization yield.

  4. Excitation and charge transfer to 2s and 2p states in 1 - 20-keV H+-H collisions

    NASA Astrophysics Data System (ADS)

    Fritsch, W.; Lin, C. D.

    1982-08-01

    Electron excitation and transfer to 2s and 2p states in H+-H (1s) collisions is studied in the energy range from 1 to 20 keV with the use of a modified two-center atomic-expansion method. It is shown that the inclusion of united-atom orbitals, in addition to the atomic orbitals of the separated atoms, in a two-center expansion allows for the extension of this method to the low-collision-energy regime. The results of our calculations at low energies from 1 to 5 keV agree with experiments and with the recent multistate molecular-orbital calculations by Kimura and Thorson but differ from the molecular-orbital calculations by Crothers and Hughes. At higher energies our results agree qualitatively with experiments and confirm the dip in 2s and 2p excitation cross sections at E~11 keV. The impact-parameter dependence of excitation and capture probabilities is also examined to illustrate the evolution of the excitation mechanism from the rotational coupling at lower collision energies to the direct excitation process at higher energies.

  5. Lifetime of the 2795 keV Jpi = 1+\\/2 level in 21Ne

    Microsoft Academic Search

    L. K. Fifield; W. N. Catford; E. F. Garman; I. F. Wright

    1983-01-01

    The mean life of the 2795 keV 1+\\/2 level in 21Ne has been measured using the 21C(13C, alphagamma)21Ne reaction and a variant of the Doppler-shift attenuation method. The result obtained was tau = 7.9 +\\/- 1.8 fs. In addition, the separation of the 2789 (1-\\/2) and 2795 (1+\\/2) keV levels in 21Ne been measured as 5.91 +\\/- 0.31 keV. The

  6. Lifetime of the 91.5 keV state in 151Sm

    Microsoft Academic Search

    S. Hofmann; P. Steiner; G. Weyer

    1971-01-01

    The gamma-transitions in 151Sm following the beta-decay of 28 h 151Pm have been studied with a high-resolution Ge detector. No evidence for levels proposed earlier at 245.6 keV and 280 keV could be found, while weakly populated levels at 306.7 and 395.6 keV were confirmed. On the basis of gammagamma delayed coincidence measurements using NaI(Tl) detectors, the half-life of the

  7. Digging gold: keV He+ ion interaction with Au

    PubMed Central

    Veligura, Vasilisa; Hlawacek, Gregor; Berkelaar, Robin P; Zandvliet, Harold J W; Poelsema, Bene

    2013-01-01

    Summary Helium ion microscopy (HIM) was used to investigate the interaction of a focused He+ ion beam with energies of several tens of kiloelectronvolts with metals. HIM is usually applied for the visualization of materials with extreme surface sensitivity and resolution. However, the use of high ion fluences can lead to significant sample modifications. We have characterized the changes caused by a focused He+ ion beam at normal incidence to the Au{111} surface as a function of ion fluence and energy. Under the influence of the beam a periodic surface nanopattern develops. The periodicity of the pattern shows a power-law dependence on the ion fluence. Simultaneously, helium implantation occurs. Depending on the fluence and primary energy, porous nanostructures or large blisters form on the sample surface. The growth of the helium bubbles responsible for this effect is discussed. PMID:23946914

  8. Digging gold: keV He(+) ion interaction with Au.

    PubMed

    Veligura, Vasilisa; Hlawacek, Gregor; Berkelaar, Robin P; van Gastel, Raoul; Zandvliet, Harold J W; Poelsema, Bene

    2013-01-01

    Helium ion microscopy (HIM) was used to investigate the interaction of a focused He(+) ion beam with energies of several tens of kiloelectronvolts with metals. HIM is usually applied for the visualization of materials with extreme surface sensitivity and resolution. However, the use of high ion fluences can lead to significant sample modifications. We have characterized the changes caused by a focused He(+) ion beam at normal incidence to the Au{111} surface as a function of ion fluence and energy. Under the influence of the beam a periodic surface nanopattern develops. The periodicity of the pattern shows a power-law dependence on the ion fluence. Simultaneously, helium implantation occurs. Depending on the fluence and primary energy, porous nanostructures or large blisters form on the sample surface. The growth of the helium bubbles responsible for this effect is discussed. PMID:23946914

  9. Measurement of the 10 keV resonance in the B10(p,?0)Be7 reaction via the Trojan Horse method

    NASA Astrophysics Data System (ADS)

    Spitaleri, C.; Lamia, L.; Puglia, S. M. R.; Romano, S.; La Cognata, M.; Crucillà, V.; Pizzone, R. G.; Rapisarda, G. G.; Sergi, M. L.; Del Santo, M. Gimenez; Carlin, N.; Munhoz, M. G.; Souza, F. A.; Szanto de Toledo, A.; Tumino, A.; Irgaziev, B.; Mukhamedzhanov, A.; Tabacaru, G.; Burjan, V.; Kroha, V.; Hons, Z.; Mrazek, J.; Zhou, Shu-Hua; Li, Chengbo; Wen, Qungang; Wakabayashi, Y.; Yamaguchi, H.; Somorjai, E.

    2014-09-01

    The B10(p ,?0)Be7 bare nucleus astrophysical S (E) factor has been measured for the first time at energies from about 100 keV down to about 5 keV by means of the Trojan Horse method (THM). In this energy region, the S (E) factor is strongly dominated by the 8.699 MeV C11 level (J?=52+), producing an s-wave resonance centered at about 10 keV in the entrance channel. Up to now, only the high-energy tail of this resonance has been measured, while the low-energy trend is extrapolated from the available direct data. The THM has been applied to the quasifree H2(B10,?0 Be7)n reaction induced at a boron-beam energy of 24.5 MeV. An accurate analysis leads to the determination of the B10(p ,?0)Be7 S (E) factor and of the corresponding electron screening potential Ue, thus giving for the first time an independent evaluation of it.

  10. A fresh look at keV sterile neutrino dark matter from frozen-in scalars

    NASA Astrophysics Data System (ADS)

    Adulpravitchai, Adisorn; Schmidt, Michael A.

    2015-01-01

    Sterile neutrinos with a mass of a few keV can serve as cosmological warm dark matter. We study the production of keV sterile neutrinos in the early universe from the decay of a frozen-in scalar. Previous studies focused on heavy frozen-in scalars with masses above the Higgs mass leading to a hot spectrum for sterile neutrinos with masses below 8 - 10 keV. Motivated by the recent hints for an X-ray line at 3.55 keV, we extend the analysis to lighter frozen-in scalars, which allow for a cooler spectrum. Below the electroweak phase transition, several qualitatively new channels start contributing. The most important ones are annihilation into electroweak vector bosons, particularly W -bosons as well as Higgs decay into pairs of frozen-in scalars when kinematically allowed.

  11. Electron back-scattering coefficient below 5 keV: Analytical expressions and surface-barrier effects

    NASA Astrophysics Data System (ADS)

    Cazaux, J.

    2012-10-01

    Simple analytical expressions for the electron backscattering coefficient, ?, are established from published data obtained in the ˜0.4-5 keV range for 21 elements ranging from Be to Au. They take into account the decline in ? with a decrease in energy E° for high-Z elements and the reverse behavior for low-Z elements. The proposed expressions for ? (E°) lead to crossing energies situated in the 0.4-1 keV range and they may be reasonably extended to any of the other elements—via an interpolation procedure—to metallic alloys and probably to compounds. The influence of the surface barrier on the escape probability of the back-scattered electrons is next evaluated. This evaluation provides a theoretical basis to explain the observed deviation between various published data as a consequence of surface contamination or oxidation. Various practical applications and strategies are deduced for the ?-measurements in dedicated instruments as well for the image interpretation in low voltage scanning electron microscopy based on the backscattered electron detection. In this microscopy, the present investigation allows to generalize the scarce contrast changes and contrast reversals previously observed on multi elemental samples and it suggests the possibility of a new type of contrast: the work function contrast.

  12. Experiment of ~200 keV electron pitch angle diffusion near loss cone boundary.

    NASA Astrophysics Data System (ADS)

    Lee, J.

    2014-12-01

    In this presentation, we show the ~200 keV electron pitch angle distribution near loss cone boundary and derive the minimum pitch angle diffusion coefficients calculated from the observation. Solid-state detectors aboard low altitude satellite, STSAT-1, were used for the measurements of the electron energy spectra. In order to measure the pitch angle distribution, we rotated the satellite's attitude about 90° with respect to the geomagnetic field line. The results show sharp boundary at the loss cone angle of 55°. To demonstrate the pitch angle distribution, we simulated drift loss and diffusion effect for longitude by solving the diffusion equation. While the pitch angle distribution measurements were performed at the altitude of 700 km, latitude of 70° and longitude of 130°E, the drift electrons are lost in the SAA region. Accordingly, the observed electrons are results of pitch angle diffusion from loss cone boundary and we can estimate minimum diffusion coefficient. In our model, the pitch angle diffusion coefficient should be larger than 1.0x105 rad2/sec

  13. The 3 H(d , ?) Reaction at Ec . m . <= 300 keV

    NASA Astrophysics Data System (ADS)

    Parker, C. E.; Brune, C. R.; Massey, T. N.; O'Donnell, J. E.; Richard, A. L.; Sayre, D. B.

    2015-04-01

    The 3 H(d , ?) 5He reaction has been measured using a 500-keV pulsed deuteron beam incident on a stopping titanium tritide target at the Edwards Accelerator Laboratory. The time-of-flight technique has been used to distinguish the ?-rays from neutrons in the bismuth germinate (BGO) ?-ray detector. A stilbene scintillator and an NE-213 scintillator have been used to detect the neutrons from the 3 H(d , n) ? reaction using both the pulse-shape discrimination and time-of-flight techniques. A newly designed target holder with a silicon surface barrier detector to simultaneously measure ?-particles to normalize the number of neutrons, along with a new titanium tritide target, was incorporated for subsequent measurements. The ?-rays have been measured at laboratory angles of 0 °, 45 °, 90 °, and 135 °. Information about the ?-ray energy distribution for the unbound ground state and first excited state of 5He can be obtained experimentally by comparing the BGO data to Monte Carlo simulations. The 3 H(d , ?) /3 H(d , n) branching ratio has also been measured. Data analysis is currently underway for the subsequent measurements. This work is supported in part by Lawrence Livermore National Laboratory and the U.S. D.O.E. (NNSA) through Grant No. DE-NA0001837.

  14. The Swift/Fermi GRB 080928 from 1 eV to 150 keV

    NASA Technical Reports Server (NTRS)

    Sonbas, Eda; Rossi, A.; Schulze, S.; Klose, S.; Kann, D. A.; Ferrero, P.; NicuesaGuelbenzu, A.; Rau, A.; Kruehler, T.; Greiner, J.; Schady, P.; Afonso, P. M. J.; Clemens, C.; Filgas, R.; KuepcuYoldas, A.; McBreen, S.; Olivares, F.; Szokoly, G.; Yoldas, A.; Krimm, H. A.; Johannesson, G.; Panaitescu, A.; Yuan, F.; Pandey, S. B.; Akerlof, C. W.

    2010-01-01

    We present the results of a comprehensive study of the Gamma-Ray Burst 080928 and of its afterglow. GRB 08092 was a long burst detected by Swift/BAT and Fermi/GBM, It is one of the exceptional cases where optical emission was already detected when the GRB itself was still radiating in the gamma-ray band. for nearly 100 seconds simultaneous optical X-ray and gamma-ray data provide a coverage of the spectral energy distribution of the transient source from about 1 eV to 150 keV. Here we analyze the prompt emission, constrain its spectral propertIes. and set lower limits on the initial Lorentz factor of the relativistic outflow, In particular. we show that the SED during the main prompt emission phase is in agreement with synchrotron radiation. We construct the optical/near-infrared light curve and the spectral energy distribution based on Swift/UVOT. ROTSE-Illa (Australia) and GROND (La Silla) data and compare it to the X-ray light curve retrieved from the Swift/XRT repository. We show that its bumpy shape can be modeled by multiple energy injections into the forward shock. Furthermore, we provide evidence that the temporal and spectral evolution of the first strong flare seen in the early X-ray light curve can be explained by large-angle emission. Finally, we report on the results of our search for the GRB host galaxy, for which only a deep upper limit can be provided.

  15. ACCURATE MEASUREMENT OF THE HALF LIFE OF THE 91 kev STATE OF 147 PROMETHIUM

    Microsoft Academic Search

    Beckhuis

    1962-01-01

    ABS>The half life of the 91-kev state of Pm¹⁴⁷ is measured as ; (2.59 plus or minus 0.02) nsec. The Pm¹⁴⁷ is produced in the beta decay ; of Nd¹⁴⁷, and the half iife is found by determining the time lag between ; the beta particle and the L conversion eiectrons produced in the decay of the 91-; kev state.

  16. The EPIC/MOS view of the 2-8 keV Cosmic X-ray Background Spectrum

    E-print Network

    A. De Luca; S. Molendi

    2004-02-10

    We have measured the spectrum of the Cosmic X-ray Background (CXB) in the 2-8 keV range with the high throughput EPIC/MOS instrument onboard XMM-Newton. A large sample of high galactic latitude observations was used, covering a total solid angle of 5.5 square degrees. Our study is based on a very careful characterization and subtraction of the instrumental background, which is crucial for a robust measurement of the faintest diffuse source of the X-ray sky. The CXB spectrum is consistent with a power law having a photon index Gamma=1.41+/-0.06, with a 2-10 keV flux of (2.24+/-0.16)x10^(-11) erg/(cm^2 s deg) (90% confidence level, including the absolute flux calibration uncertainty). Our results are in excellent agreement with two of the most recent CXB measurements, performed with BeppoSAX LECS/MECS data (Vecchi et al. 1999) and with an independent analysis of XMM-Newton EPIC/MOS data (Lumb et al. 2002), providing a very strong constrain to the absolute sky surface brightness in this energy range, so far affected by a ~40% uncertainty. Our measurement immediately implies that the fraction of CXB resolved by the recent deep X-ray observations in the 2-10 keV band is of 80+/-7% (1 sigma), suggesting the existence of a new population of faint sources, largely undetected within the current sensitivity limits of the deepest X-ray surveys.

  17. Comparison of calculated spectra for the interaction of photons in a liquid scintillator. Example of 54Mn 835 keV emission.

    PubMed

    Cassette, P; Ahn, G H; Alzitzoglou, T; Aubineau-Lanièce, I; Bochud, F; Garcia Torano, E; Grau Carles, A; Grau Malonda, A; Kossert, K; Lee, K B; Laedermann, J P; Simpson, B R S; van Wyngaardt, W M; Zimmerman, B E

    2006-01-01

    The CIEMAT/NIST and TDCR methods in liquid scintillation counting, initially developed for the activity standardization of pure-beta radionuclides, have been extended to the standardization of electron capture and beta-gamma radionuclides. Both methods require the calculation of the energy spectrum absorbed by the liquid scintillator. For radionuclides emitting X-rays or gamma-rays, when the energy is greater than a few tens of keV the Compton interaction is important and the absorption is not total. In this case, the spectrum absorbed by the scintillator must be calculated using analytical or stochastic models. An illustration of this problem is the standardization of 54Mn, which is a radionuclide decaying by electron capture. The gamma transition, very weakly converted, leads to the emission of an 835 keV photon. The calculation of the detection efficiency of this radionuclide requires the calculation of the energy spectrum transferred to the scintillator after the absorption of the gamma ray and the associated probability of absorption. The validity of the method is thus dependent on the correct calculation of the energy transferred to the scintillator. In order to compare the calculation results obtained using various calculation tools, and to provide the metrology community with some information on the choice of these tools, the LS working group of the ICRM organised a comparison of the calculated absorbed spectra for the 835 keV photon of 54Mn. The result is the spectrum of the energy absorbed by the scintillator per emission of an 835 keV gamma ray. This exercise was proposed for a standard 20 ml LS glass vial and for LS cocktail volumes of 10 and 15 ml. The calculation was done for two different cocktails: toluene and a widely used commercial cocktail, Ultima Gold. The paper describes the results obtained by nine participants using a total of 12 calculation codes. PMID:16600600

  18. Optimization of multilayer reflectivity and bandpass for soft to hard x-ray applications [0.1-200 keV

    NASA Astrophysics Data System (ADS)

    Vestli, K.; Ziegler, E.

    1996-09-01

    In the last decades, the major motivation for manufacturing multilayer mirrors has been in soft x-ray applications, particularly for astronomy, microlithography, and polarimetry. The advent of high energy synchrotron storage rings has provided a new significant impetus emphasizing high energy applications and especially when flux, rather than resolution, is desired. In this paper we present the reflection properties of the most promising multilayer material combinations for the energy range from 0.1 keV up to 200 keV. Previous calculations by Rosenbluth were limited to a maximum of 2 keV and to multilayers composed of pure elements and operating under normal incidence. As alloys might be essential for a smooth growth and/or for stability under high heat load, our screening consisted of a list of up to 300 solids having a melting point above 100°C and that could be deposited in a sputtering process. A full computer search calculates 45000 multilayer combinations for each angle (or multilayer d-spacing) and energy of operation, the only necessary input variables. Other manufacture-related parameters can be specified to give a more realistic picture of the performance. As the number of layers is often limited, a nonperiodic design could minimize absorption effects.

  19. INTEGRAL Observations of the Galactic 511 keV Emission and MeV Gamma-ray Astrophysics

    NASA Technical Reports Server (NTRS)

    Watanabe, Ken

    2005-01-01

    Although there are a number of interesting phenomena, such as Nucleosynthesis in stars, in the MeV energy region, the observations have been difficult due to a small signal to noise (background) ratio (less than 1%). While NASA's Compton Gamma-ray Observatory (CGRO) enabled us to explore the Gamma-ray universe, ESA's INTEGRAL mission, launched in 2002, is providing us more detailed information with its superior energy and angular resolution. We will briefly discuss some of the current issues in MeV Gamma-ray Astrophysics. Then, we will focus on the Galactic 511 keV emission with the latest INTEGRAL observations, and talk about challenges we currently have.

  20. Nuclear resonant forward scattering of synchrotron radiation from 121 Sb at 37.13 keV.

    SciTech Connect

    Wille, H. C.; Shvydko, Y. V.; Alp, E. E.; Ruter, H. D.; Leupold, O.; Sergueev, I.; Ruffer, R.; Barla, A.; Sanchez, J. P.; X-Ray Science Division; European Synchrotron Radiation Facility; Univ. of Hamburg; Hamburder Synchrotronstrahlungslabor

    2006-02-22

    We report on the observation of nuclear resonant forward scattering of synchrotron radiation from {sup 121}Sb nuclei. A temperature stabilized {alpha}Al{sub 2}O{sub 3} crystal Bragg backscattering high-resolution monochromator with a relative energy resolution of 2 x 10{sup -7} was introduced. As first spectroscopic applications the hyperfine parameters in Sb{sub 2}O{sub 3}, USb and DySb were determined. The energy of the nuclear transition in {sup 121}Sb was measured to be 37.1298(2)keV, 40 times more precisely than reported before. The results open the field of nuclear resonance spectroscopy on antimony compounds taking advantage of the outstanding features of 3rd-generation synchrotron sources. Nuclear resonance scattering on Sb compounds at these sources allows element-specific dynamical studies on thermoelectric materials as well as studies on magnetism in micro- and nanometer dimensional systems like spintronic devices.

  1. Injection and diffusive transport of suprathermal through energetic solar flare protons (35 keV to 20 MeV)

    NASA Technical Reports Server (NTRS)

    Beeck, J.; Mason, G. M.; Hamilton, D. C.; Marsden, R. G.; Sanderson, T. R.

    1990-01-01

    Consideration is given to the injection and interplanetary propagation of low-energy protons caused by the solar particle event of July 20, 1981, in which flare protons in the range from 35 keV to 20 MeV were observed by instruments on ISEE 3. The observed time-intensity and time-anisotropy profiles were fitted over the entire energy range using a model based on the spherically symmetric Fokker-Plank equation, including convection, diffusion, and adiabatic deceleration. The results are used to discuss the behavior of the radial interplanetary diffusion coefficient and the scattering mean free path for protons. Also, evidence is found for diffusive coronal shock acceleration of protons during the event.

  2. Compact focusing spectrometer: Visible (1 eV) to hard x-rays (200 keV)

    SciTech Connect

    Baronova, E. O.; Stepanenko, A. M. [RNC “Kurchatov Institute”, 123098 Moscow (Russian Federation); Pereira, N. R., E-mail: ninorpereira@gmail.com [Ecopulse, Inc., 7844 Vervain Ct, Springfield, Virginia 22152 (United States)

    2014-11-15

    A low-cost spectrometer that covers a wide range of photon energies can be useful to teach spectroscopy, and for simple, rapid measurements of the photon spectrum produced by small plasma devices. The spectrometer here achieves its wide range, nominally from 1 eV to 200 keV, with a series of spherically and cylindrically bent gratings or crystals that all have the same shape and the same radius of curvature; they are complemented by matching apertures and diagnostics on the Rowland circle that serves as the circular part of the spectrometer's vacuum vessel. Spectral lines are easily identified with software that finds their positions from the dispersion of each diffractive element and the known energies of the lines.

  3. The study of structural properties of 100 keV hydrogen ion implanted semi-insulating GaAs single crystals

    Microsoft Academic Search

    M. Udhayasankar; J. Kumar; P. Ramasamy; K. Sekar; B. Sundaravel; C. Ferrari; L. Lazzarini; P. Magudapathy; K. G. M Nair

    1999-01-01

    100 keV hydrogen ion implantation has been carried out on undoped semi-insulating ?100? gallium arsenide single crystals for various ion doses at room temperature. The structural properties due to high dose, low energy hydrogen ion implantation has been investigated using X-ray double crystal diffractometry (DCD) analysis, Rutherford backscattering spectrometry and channeling (RBS\\/C) experiments and transmission electron microscopy (TEM) analysis. By

  4. Degradation behaviors of electrical properties of GaInP\\/GaAs\\/Ge solar cells under <200 keV proton irradiation

    Microsoft Academic Search

    Hu Jianmin; Wu Yiyong; Xiao Jingdong; Yang Dezhuang; Zhang Zhongwei

    2008-01-01

    The degradation effects of the GaInP\\/GaAs\\/Ge triple-junction solar cells irradiated by <200keV protons are investigated on the basis of the spectral response analysis and measurements of electric property. The experimental results show that with increasing proton fluence Isc, Voc and Pmax decrease obviously. The proton energy exhibits an important influence on the degradation effects of the triple-junction cells dependent on

  5. Structural investigation of keV Ar-ion-induced surface ripples in Si by cross-sectional transmission electron microscopy

    E-print Network

    Nordlund, Kai

    O2, Ge, and GaAs, though rippling has been been observed recently in metals Ag and Cu as well.4 Amorphization of Si Refs. 15,16 by heavy ion such as Ar bombardment at keV energies occurs in a dose range 1014 have to be the same everywhere. This is a very relevant question be- cause quite recently ion-enhanced

  6. Calculation of percentile-distance ratios and scaled absorbed-dose distributions for 0.05- to 30-keV primary electrons

    NASA Astrophysics Data System (ADS)

    Wilson, W. E.; Reece, W. D., Jr.

    1991-10-01

    This document reports the results of computing Berger-type point kernels for 0.05- to 30-keV monoenergetic electrons in a water medium. A detailed-histories Monte Carlo method was used in contrast to the condensed-histories methods used by others. Good agreement with other work was found, over the common energy region. The study was performed at Pacific Northwest Laboratory as an exploratory research project.

  7. Dark matter in galaxies: the dark matter particle mass is about 7 keV

    E-print Network

    H. J. de Vega; N. G. Sanchez

    2014-11-11

    Warm dark matter (WDM) means DM particles with mass m in the keV scale. For large scales, (structures beyond ~ 100 kpc) WDM and CDM yield identical results which agree with observations. For intermediate scales, WDM gives the correct abundance of substructures. Inside galaxy cores, below ~ 100 pc, N-body WDM classical physics simulations are incorrect because at such scales quantum WDM effects are important. WDM quantum calculations (Thomas-Fermi approach) provide galaxy cores, galaxy masses, velocity dispersions and density profiles in agreement with the observations. For a dark matter particle decoupling at thermal equilibrium (thermal relic), all evidences point out to a 2 keV particle. Remarkably enough, sterile neutrinos decouple out of thermal equilibrium with a primordial power spectrum similar to a 2 keV thermal relic when the sterile neutrino mass is about 7 keV. Therefore, WDM can be formed by 7 keV sterile neutrinos. Excitingly enough, Bulbul et al. (2014) announced the detection of a cluster X-ray emission line that could correspond to the decay of a 7.1 keV sterile neutrino and to a neutrino decay mixing angle of \\sin^2 2 \\theta ~ 7 10^{-11} . This is a further argument in favour of sterile neutrino WDM. Baryons, represent 10 % of DM or less in galaxies and are expected to give a correction to pure WDM results. The detection of the DM particle depends upon the particle physics model. Sterile neutrinos with keV scale mass (the main WDM candidate) can be detected in beta decay for Tritium and Renium and in the electron capture in Holmiun. The sterile neutrino decay into X rays can be detected observing DM dominated galaxies and through the distortion of the black-body CMB spectrum. So far, not a single valid objection arose against WDM.

  8. Common Origin of 3.55 keV X-Ray Line and Galactic Center Gamma Ray Excess in a Radiative Neutrino Mass Model

    E-print Network

    Debasish Borah; Arnab Dasgupta; Rathin Adhikari

    2015-03-20

    We attempt to simultaneously explain the recently observed 3.55 keV X-ray line in the analysis of XMM-Newton telescope data and the galactic center gamma ray excess observed by the Fermi gamma ray space telescope within an abelian gauge extension of standard model. We consider a two component dark matter scenario with a mass difference 3.55 keV such that the heavier one can decay into the lighter one and a photon with energy 3.55 keV. The lighter dark matter candidate is protected from decaying into the standard model particles by a remnant $Z_2$ symmetry into which the abelian gauge symmetry gets spontaneously broken. If the mass of the dark matter particle is chosen to be within $31-40$ GeV, then this model can also explain the galactic center gamma ray excess if the dark matter annihilation into $b\\bar{b}$ pairs has a cross section of $\\langle \\sigma v \\rangle \\simeq (1.4-2.0) \\times 10^{-26} \\; \\text{cm}^3/\\text{s}$. We constrain the model from the requirement of producing correct dark matter relic density, 3.55 keV X-ray line flux and galactic center gamma ray excess. We also impose the bounds coming from dark matter direct detection experiments as well as collider limits on additional gauge boson mass and coupling. We also briefly discuss how this model can give rise to sub-eV neutrino masses at tree level as well as one loop level while keeping the dark matter mass at few tens of GeV. We also show the natural origin of keV mass splitting between two electroweak scale dark matter particles at one loop level in this model.

  9. The 0.3-30 keV Spectra of Powerful Starburst Galaxies: NuSTAR and Chandra Observations of NGC 3256 and NGC 3310

    NASA Astrophysics Data System (ADS)

    Lehmer, B. D.; Tyler, J. B.; Hornschemeier, A. E.; Wik, D. R.; Yukita, M.; Antoniou, V.; Boggs, S.; Christensen, F. E.; Craig, W. W.; Hailey, C. J.; Harrison, F. A.; Maccarone, T. J.; Ptak, A.; Stern, D.; Zezas, A.; Zhang, W. W.

    2015-06-01

    We present nearly simultaneous Chandra and NuSTAR observations of two actively star-forming galaxies within 50 Mpc: NGC 3256 and NGC 3310. Both galaxies are significantly detected by both Chandra and NuSTAR, which together provide the first-ever spectra of these two galaxies spanning 0.3–30 keV. The X-ray emission from both galaxies is spatially resolved by Chandra; we find that hot gas dominates the E < 1–3 keV emission while ultraluminous X-ray sources (ULXs) provide majority contributions to the emission at E > 1–3 keV. The NuSTAR galaxy-wide spectra of both galaxies follow steep power-law distributions with ? ? 2.6 at E > 5–7 keV. Using new and archival Chandra data, we search for signatures of heavily obscured or low luminosity active galactic nuclei (AGNs). We find that both NGC 3256 and NGC 3310 have X-ray detected sources coincident with nuclear regions; however, the steep NuSTAR spectra of both galaxies restricts these sources to be either low luminosity AGNs (L2?10 keV/LEdd ? 10?5) or non-AGNs in nature (e.g., ULXs or crowded X-ray sources that reach L2?10 keV ? 1040 erg s?1 cannot be ruled out). Combining our constraints on the 0.3–30 keV spectra of NGC 3256 and NGC 3310 with equivalent measurements for nearby star-forming galaxies M83 and NGC 253, we analyze the star formation rate (SFR) normalized spectra of these starburst galaxies. The spectra of all four galaxies show sharply declining power-law slopes at energies above 3–6 keV primarily due to ULX populations. Our observations therefore constrain the average spectral shape of galaxy-wide populations of luminous accreting binaries (i.e., ULXs). Interestingly, despite a completely different galaxy sample selection, emphasizing here a range of SFRs and stellar masses, these properties are similar to those of super-Eddington accreting ULXs that have been studied individually in a targeted NuSTAR ULX program. We also find that NGC 3310 exhibits a factor of ?3–10 elevation of X-ray emission over the other star-forming galaxies due to a corresponding overabundance of ULXs. We argue that the excess of ULXs in NGC 3310 is most likely explained by the relatively low metallicity of the young stellar population in this galaxy, a property that is expected to produce an excess of luminous X-ray binaries for a given SFR.

  10. Analysis of chromosome aberrations in human peripheral lymphocytes induced by 5.4 keV x-rays.

    PubMed

    Roos, H; Schmid, E

    1998-02-01

    Irradiation of human lymphocytes by x-rays has been seen, in past studies, to produce increasing frequencies of chromosome aberrations at lower x-ray energies. However, in one earlier irradiation experiment with chromium x-rays, the relative biological effectiveness (RBE) did not appear to be larger than that of hard x-rays, especially at higher doses. A possible reason for this unexpected result may have been the irradiation and culture conditions. We have, therefore, in the present study used a technique that has been developed in our laboratory to ensure uniformity of irradiation within lymphocytes and to avoid artefacts due to the cell cycle kinetics. Monolayers of 3-h-stimulated lymphocytes were exposed to 5.4 keV x-rays. A linear-quadratic dose-response was found for dicentrics. The comparison to an earlier finding with 220 kV x-rays shows the expected result of the RBE of the 5.4 keV x-rays to be above that of 220 kV x-rays. The intercellular distribution of dicentrics did not differ significantly from a Poisson distribution. PMID:9523341

  11. A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371

    E-print Network

    Iaria, R; Matranga, M; Galiano, C G; D'Aì, A; Riggio, A; Burderi, L; Sanna, A; Ferrigno, C; Del Santo, M; Pintore, F; Robba, N R

    2015-01-01

    We analyse all available X-ray observations of X1822-371 made with XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to constrain the spectral shape of the continuum emission well. We use the model already proposed for this source, consisting of a Comptonised component absorbed by interstellar matter and partially absorbed by local neutral matter, and we added a Gaussian feature in absorption at $\\sim 0.7$ keV. This addition significantly improves the fit and flattens the residuals between 0.6 and 0.8 keV. We interpret the Gaussian feature in absorption as a cyclotron resonant scattering feature (CRSF) produced close to the neutron star surface and derive the magnetic field strength at the surface of the neutron star, $(8.8 \\pm 0.3) \\times 10^{10}$ G for a radius of 10 km. We derive the pulse period in the EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative of X1822-371 is $(-2.55...

  12. Angular scattering of 1–50 keV ions through graphene and thin carbon foils: Potential applications for space plasma instrumentation

    SciTech Connect

    Ebert, Robert W., E-mail: rebert@swri.edu [Southwest Research Institute, P. O. Drawer 28510, San Antonio, Texas 78228-0510 (United States); Allegrini, Frédéric; Fuselier, Stephen A.; Nicolaou, Georgios [Southwest Research Institute, P. O. Drawer 28510, San Antonio, Texas 78228-0510 (United States) [Southwest Research Institute, P. O. Drawer 28510, San Antonio, Texas 78228-0510 (United States); Physics and Astronomy Department, University of Texas at San Antonio, One UTSA Circle, San Antonio, Texas 78249 (United States); Bedworth, Peter; Sinton, Steve [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, California 94304 (United States)] [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, California 94304 (United States); Trattner, Karlheinz J. [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, California 94304 (United States) [Lockheed Martin Advanced Technology Center, 3251 Hanover Street, Palo Alto, California 94304 (United States); Laboratory for Atmospheric and Space Physics, University of Colorado, 1234 Innovation Drive, Boulder, Colorado 80303 (United States)

    2014-03-15

    We present experimental results for the angular scattering of ?1–50 keV H, He, C, O, N, Ne, and Ar ions transiting through graphene foils and compare them with scattering through nominal ?0.5 ?g?cm{sup ?2} carbon foils. Thin carbon foils play a critical role in time-of-flight ion mass spectrometers and energetic neutral atom sensors in space. These instruments take advantage of the charge exchange and secondary electron emission produced as ions or neutral atoms transit these foils. This interaction also produces angular scattering and energy straggling for the incident ion or neutral atom that acts to decrease the performance of a given instrument. Our results show that the angular scattering of ions through graphene is less pronounced than through the state-of-the-art 0.5 ?g?cm{sup ?2} carbon foils used in space-based particle detectors. At energies less than 50 keV, the scattering angle half width at half maximum, ?{sub 1/2}, for ?3–5 atoms thick graphene is up to a factor of 3.5 smaller than for 0.5 ?g?cm{sup ?2} (?20 atoms thick) carbon foils. Thus, graphene foils have the potential to improve the performance of space-based plasma instruments for energies below ?50 keV.

  13. Angular scattering of 1-50 keV ions through graphene and thin carbon foils: potential applications for space plasma instrumentation.

    PubMed

    Ebert, Robert W; Allegrini, Frédéric; Fuselier, Stephen A; Nicolaou, Georgios; Bedworth, Peter; Sinton, Steve; Trattner, Karlheinz J

    2014-03-01

    We present experimental results for the angular scattering of ~1-50 keV H, He, C, O, N, Ne, and Ar ions transiting through graphene foils and compare them with scattering through nominal ~0.5 ?g?cm(-2) carbon foils. Thin carbon foils play a critical role in time-of-flight ion mass spectrometers and energetic neutral atom sensors in space. These instruments take advantage of the charge exchange and secondary electron emission produced as ions or neutral atoms transit these foils. This interaction also produces angular scattering and energy straggling for the incident ion or neutral atom that acts to decrease the performance of a given instrument. Our results show that the angular scattering of ions through graphene is less pronounced than through the state-of-the-art 0.5 ?g?cm(-2) carbon foils used in space-based particle detectors. At energies less than 50 keV, the scattering angle half width at half maximum, ?(1/2), for ~3-5 atoms thick graphene is up to a factor of 3.5 smaller than for 0.5 ?g?cm(-2) (~20 atoms thick) carbon foils. Thus, graphene foils have the potential to improve the performance of space-based plasma instruments for energies below ~50 keV. PMID:24689570

  14. Range measurement of boron isotopes in silicon from 600 keV to 2 MeV

    NASA Astrophysics Data System (ADS)

    Goppelt, P.; Biersack, J. P.; Gebauer, B.; Fink, D.; Bohne, W.; Wilpert, M.; Wilpert, Th.

    1993-06-01

    Ranges of boron isotopes with masses 10 and 11 were measured in silicon for implantation energies of 600 keV, 1.0, 1.5 and 2.0 MeV by use of high-energy elastic recoil detection analysis (HE-ERDA). The measured ranges were compared with TRIM and PRAL calculations. The experimental data show a deviation to larger depth particularly at higher energies. The ratio of the ranges of the isotopes is always lower than theoretically predicted. The experimental results can be interpreted as follows: the electronic stopping, which dominates this energy regime, increases slower than expected. The maximum of the stopping power is shifted towards lower energies and is lower than calculated. In the lower energy range the stopping power must be larger than predicted leading to smaller ranges for energies up to 1 MeV. Our experiment is in good agreement with former range measurements of Behar et al. [Nucl. Instr. and Meth. B34 (1988) 316] who used the very reliable 10B(n, ?) 6Li nuclear reaction technique (neutron depth profiling: NDP), and of Svensson et al. [J. Appl. Phys. 68 (1990) 73] using secondary ion mass spectroscopy (SIMS), who both found this behavior, too.

  15. Steady State Sputtering Yields and Surface Compositions of Depleted Uranium and Uranium Carbide bombarded by 30 keV Gallium or 16 keV Cesium Ions.

    SciTech Connect

    Siekhaus, W. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Teslich, N. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Weber, P. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-23

    Depleted uranium that included carbide inclusions was sputtered with 30keV gallium ions or 16kev cesium ions to depths much greater than the ions’ range, i.e. using steady state sputtering. The recession of both the uranium’s and uranium carbide’s surfaces and the ion corresponding fluences were used to determine the steady state target sputtering yields of both uranium and uranium carbide, i.e. 6.3 atoms of uranium and 2.4 units of uranium carbide eroded per gallium ion, and 9.9 uranium atoms and 3.65 units of uranium carbide eroded by cesium ions. The steady state surface composition resulting from the simultaneous gallium or cesium implantation and sputter-erosion of uranium and uranium carbide were calculated to be U??Ga??, (UC)??Ga?? and U??Cs?, (UC)??Cs??, respectively.

  16. Origin of the 871-keV gamma ray and the ``oxide'' attribute

    SciTech Connect

    AJ Peurrung; RJ Arthur; BD Geelhood; RD Scheele; RJ Elovich; SL Pratt

    2000-03-22

    This work concludes the investigation of the oxide attribute of current interest for the characterization of stored plutonium. Originally it was believed that the presence of oxide could be ascertained by measurement of the 871-keV line in a high-resolution gamma-ray spectrum. However, recent work has suggested that the 871-keV gamma ray in plutonium oxide arises from the reaction {sup 14}N({alpha},p){sup 17}O rather than the inelastic scattering reaction {sup 17}O({alpha},{alpha}{prime}){sup 17}O*. This conclusion, though initially surprising, was obtained during efforts to determine the relative importance of americium and plutonium alpha-particle decay for the production of the 871-keV gamma ray. Several questions were raised by previous experiments: What role, if any does {sup 17}O have in the generation of the 871-keV gamma ray? How does sufficient nitrogen come to be present in plutonium oxide? Under what conditions is the 871-keV gamma ray measurable in plutonium oxide? This paper describes the answers to these questions.

  17. Detection of 1 - 100 keV x-rays from high intensity, 500 fs laser- produced plasmas using charge-coupled devices

    SciTech Connect

    Dunn, J.; Young, B.K.F.; Conder, A.D.; Stewart, R.E.

    1996-01-01

    We describe a compact, vacuum compatible, large format, charge- coupled device (CCD) camera for scientific imaging and detection of 1- 100 keV x rays in experiments at LLNL JANUS-1ps laser. A standard, front-illuminated, multi-pin phase device with 250 k electron full well capacity, low dark current (10 pA/cm{sup 2} at 20 C) and low read noise (5 electron rms) is cooled to -35 C to give the camera excellent 15-bit dynamic range and signal-to-noise response. Intensity and x-ray energy linear response were determined for optical and x-ray (<65 keV) photons and are in excellent agreement. Departure from linearity was less than 0.7%. Inherent linearity and energy dispersive characteristics of CCD cameras are well suited for hard x-ray photon counting. X-rays absorbed within the depletion and field-free regions can be distinguished by studying the pulse height spectrum. Results are presented for the detection of 1-100 keV Bremsstrahlung continuum, K-shell and L-shell fluorescence spectra emitted from high intensity (10{sup 18}W cm{sup -2}), 500 fs laser- produced plasmas.

  18. The Jpi = 3- doublet at Ex = 6241 keV in 18F: Isospin mixing

    Microsoft Academic Search

    W. E. Kieser; R. E. Azuma; I. Berka; K. P. Jackson; A. B. McDonald; H. B. Mak; W. McLatchie

    1979-01-01

    The resonance previously observed at Ex = 6241 keV in the reactions 17O(p, gamma)18F and 14N(alpha, gamma)18F has been found to be a closely separated doublet (DeltaEx = 2.09+\\/-0.04 keV). Resonance strengths in 17O(p, gamma)18F, 17O(p, alpha)14N and 14N(alpha, gamma)18 have been measured and partial widths for the resonance states have been obtained. The doublet was further investigated by means

  19. Sputtered-sliced multilayers: Zone plates and transmission gratings for 8-keV x rays

    SciTech Connect

    Bionta, R.M.; Ables, E.; Cook, K.J.; Edwards, O.D.; Gabriele, P.C.; Jankowski, A.F.; Makowiecki, D.M.; Ott, L.L.; Thomas, N.

    1988-07-29

    We have made and tested several sliced multilayer structures that can function as transmissive x-ray optical elements (diffraction gratings, zone plates and phase gratings) at 8-keV. Both amplitude-modulating and phase-modulating devices have been produced. We show data taken in the beam of a 8 keV x-ray source that demonstrate diffraction and focusing. The diffraction patterns produced by the multilayer devices closely match theoretical predictions. Such transmissive optics have the potential for a wide application to high-resolution microscope and spectrometer systems. 6 refs., 15 figs.

  20. g-factor of the 91.5 keV state in 151Sm

    Microsoft Academic Search

    H. Drost; H. von Lojewski; K. Palow; R. Wallenstein; G. Weyer

    1974-01-01

    The g-factor of the 91.5 keV state in 151Sm has been measured by the TDPAC method using gammagamma cascades following the beta-decay of 28 h 151Pm. The result is g = -0.21+\\/-0.01. The anisotropy of the angular correlation for the 232.2-25.7 keV cascade is measured to be A = +0.058+\\/-0.006. From this an M1\\/E2 mixing ratio of delta2 = 0.008+\\/-0.002

  1. Large angle elastic and inelastic scattering of 14.93 keV photons

    Microsoft Academic Search

    P. Singh; D. Mehta; S. Kumar; M. Sharma; S. Puri; J. S. Shahi; N. Singh

    2004-01-01

    Elastic and inelastic scattering cross-sections for the 14.93 keV photons (Y-K? X-rays) were measured at an angle of 141° in the elements with 6?Z?92 and 1?Z?50, respectively. A reflection mode geometrical arrangement involving a Y-foil excited by the 59.54 keV ?-rays from the 241Am radioisotope as photon source and an HPGe\\/Si(Li) detector was used. The measurements were performed under vacuum

  2. A 9 month long soft X-ray survey of the Large Magellanic Cloud. I - X-ray map at 1/4 keV

    NASA Technical Reports Server (NTRS)

    Singh, K. P.; Nousek, J. A.; Burrows, D. N.; Garmire, G. P.

    1987-01-01

    Data from the HEAO 1 low energy detector was used to map the diffuse 1/4 keV X-ray background around the LMC. Data was collected over 9 mos in 1977-1978 using detectors sensitive in the range 0.18-2.8 keV. Diffuse emission, rather than absorption, was observed from the LMC, as were two large emission (2 million K) regions with very low surface brightness. The regions coincided with the Shapley III supergiant shell of optical nebulosity and the LMC bar. Higher spatial resolution imagery is required if the emission features are to be confirmed as the same type of phenomena as the X-ray superbubble in Cygnus.

  3. New limit on the mass of 14.4-keV solar axions emitted in an M1 transition in {sup 57}Fe nuclei

    SciTech Connect

    Derbin, A. V., E-mail: derbin@pnpi.spb.ru; Muratova, V. N.; Semenov, D. A.; Unzhakov, E. V. [Russian Academy of Sciences, Petersburg Nuclear Physics Institute (Russian Federation)

    2011-04-15

    Axions of energy 14.4 keV that originated from the M1 transition in {sup 57}Fe nuclei in the Sun were sought by using the resonance-absorption reaction A+{sup 57}Fe {yields} {sup 57}Fe* {yields} {sup 57}Fe+{gamma} (14.4 keV). Asectioned Si(Li) detector arranged in a low-background facility was used to record photons from this reaction. This resulted in setting a new limit on the axion couplings to nucleons, vertical bar -1.19g{sub AN}{sup 0} + g{sub AN}{sup 3} vertical bar {<=} 3.0 Multiplication-Sign 10{sup -6}. Within the hadronic-axion model, the respective constraint on the axion mass is m{sub A} {<=} 145 eV (at a 95% C.L.).

  4. The {sup 14}C(n,{gamma}) cross section between 10 keV and 1 MeV

    SciTech Connect

    Reifarth, R.; Couture, A.; Haight, R. C.; Rundberg, R. S.; Wilhelmy, J. B. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Heil, M.; Dababneh, S.; Kaeppeler, F.; Plag, R. [Forschungszentrum Karlsruhe, Institut fuer Kernphysik, P. O. Box 3640, D-76021 Karlsruhe (Germany); Forssen, C. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Fundamental Physics, Chalmers University of Technology, S-412 96 Goeteborg (Sweden); Besserer, U.; Doerr, L. [Forschungszentrum Karlsruhe, Tritiumlabor, P. O. Box 3640, D-76021 Karlsruhe (Germany); Goerres, J.; O'Brien, S.; Wiescher, M. [University of Notre Dame, Physics Department, Notre Dame, Indiana 46556 (United States); Mengoni, A. [CERN, CH-1211 Geneva 23 (Switzerland); Patronis, N. [Nuclear Physics Laboratory, Department of Physics, The University of Ioannina, GR-45110 Ioannina (Greece)

    2008-01-15

    The neutron capture cross section of {sup 14}C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The {sup 14}C(n,{gamma}) reaction is also important for the validation of the Coulomb dissociation method, where the (n,{gamma}) cross section can be indirectly obtained via the time-reversed process. So far, the example of {sup 14}C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the {sup 14}C(n,{gamma}) reaction with neutron energies ranging from 20 to 800 keV.

  5. Calorimetric measurement of electron stopping power of aluminum and copper between 11 and 127 keV

    SciTech Connect

    Hubbell, H.H. Jr.; Birkhoff, R.D.

    1982-11-01

    The stopping powers of aluminum and copper have been measured for electrons between 11 and 127 keV. Evaporated foils of about 200-nm thickness were stretched across rings and inserted into a short cylinder which was supported by thermocouple wires. Peltier heating and cooling by one thermopile were used to control foil temperature, while another thermopile measured its temperature. Calibration was accomplished by reducing beam energy until complete absorption was obtained. Delta rays produced in the foil were returned to it by repelling electrodes. Corrections were made for increased path length in the foil due to multiple elastic small-angle scattering and for spurious heating by scattered electrons striking the ring holding the foil. After correction for these effects, good agreement with the Bethe-Bloch formula was found.

  6. Chemistry and structure of beta silicon carbide implanted with high-dose aluminum. [168 keV

    SciTech Connect

    Du, Honghua; Yang, Zunde; Libera, M. (Stevens Inst. of Tech., Hoboken, NJ (United States). Dept. of Materials Science and Engineering); Jacobson, D.C. (AT and T Bell Laboratories, Murray Hill, NJ (United States)); Wang, Yu C.; Davis, R.F. (North Carolina State Univ., Raleigh, NC (United States). Dept. of Materials Science and Engineering)

    1993-02-01

    Single-crystal [beta]-SiC was implanted with aluminum to 3.90 x 10[sup 17] ions/cm[sup 2] at 168 keV at 773 K. The resultant compositional and structural characteristics were studied by Rutherford backscattering spectrometry. Auger electron spectroscopy, X-ray photoelectron spectroscopy, and cross-sectional transmission electron microscopy. No aluminum redistribution was observed during implantation. The Si-to-C ratio exhibited a negative deviation from unity in the implanted region. The shift in the photoelectron binding energies indicated the formation of aluminum carbide. The studies by electron microscopy showed that the implanted region consists of slightly misoriented [beta]-SiC crystals and textured crystalline aluminum carbide precipitates.

  7. Development of heavy mineral and heavy element database of soil sediments in Japan using synchrotron radiation X-ray powder diffraction and high-energy (116 keV) X-ray fluorescence analysis: 1. Case study of Kofu and Chiba region.

    PubMed

    Bong, Willy Shun Kai; Nakai, Izumi; Furuya, Shunsuke; Suzuki, Hiroko; Abe, Yoshinari; Osaka, Keiichi; Matsumoto, Takuya; Itou, Masayoshi; Imai, Noboru; Ninomiya, Toshio

    2012-07-10

    We have started the construction of a nationwide forensic soil sediment database for Japan based on the heavy mineral and trace heavy element compositions of stream sediments collected at 3024 points all over Japan obtained by high-resolution synchrotron X-ray powder diffraction (SR-XRD) and high-energy synchrotron X-ray fluorescence analysis (HE-SR-XRF). In this study, the performance of both techniques was demonstrated by analyzing soil sediments from two different geological regions, the Kofu and Chiba regions in Kanto province, to construct database that can be applied in the future to provenance analysis of soil evidence from a crime scene. The sediments from the quaternary volcanic lithology of the Chiba region were found to be dominated by heavy minerals of volcanic origin - orthopyroxene, clinopyroxene, and amphibole, and the REEs (rare earth elements) within the region showed similar geochemical behavior. On the other hand, four distinct heavy mineral groups were identified in the sediments of the Kofu region, where there is a great variety of underlying bedrock, and the geochemical behavior of the REEs in the sediments also varied accordingly to their geological origins. As such, our study shows that high-resolution SR-XRD data can provide information on the spatial distribution patterns of heavy minerals in stream sediments, playing an important role in determining their likely geographical origin. Meanwhile, the highly sensitive HE-SR-XRF data allow us to study the geochemical behavior of trace heavy elements, especially the REEs in the sediments, providing additional support to further constrain the likely geographical origin of the sediments determined by heavy minerals. PMID:22445767

  8. Deactivation of group III acceptors in silicon during keV electron irradiation

    SciTech Connect

    Sah, C.; Sun, J.Y.; Tzou, J.J.; Pan, S.C.

    1983-11-15

    Experimental results on p-Si metal-oxide-semiconductor capacitors (MOSC's) are presented which demonstrate the electrical deactivation of the acceptor dopant impurity during 8-keV electron irradiation not only in boron but also aluminum and indium-doped silicon. The deactivation rates of the acceptors during the 8-keV electron irradiation are nearly independent of the acceptor impurity type. The final density of the remaining active acceptor approaches nonzero values N/sub infinity/, with N/sub infinity/(B)Al--H>In-H. These deactivation results are consistent with our hydrogen bond model. The thermal annealing or regeneration rate of the deactivated acceptors in the MOSC's irradiated by 8-keV electron is much smaller than that in the MOSC's that have undergone avalanche electron injection, indicating that the keV electron irradiation gives rise to stronger hydrogen-acceptor bond.

  9. Sputtering of cryogenic films of hydrogen by keV ions: Thickness dependence and surface morphology.

    E-print Network

    . Jørgen Schou1 and Noel Hilleret2 The solid hydrogen isotopes are the most volatile solids which exist in equilibrium with vacuum. For bombardment with 10 keV hydrogen ions the sputtering yield of these solids ranges at a temperature of 2-3 K, and the thickness ranged from a fraction of a monolayer up to several thousands

  10. Dynamical framework for KeV Dirac neutrino warm dark matter

    NASA Astrophysics Data System (ADS)

    Robinson, Dean J.; Tsai, Yuhsin

    2014-08-01

    If the source of the reported 3.5 keV x-ray line is a sterile neutrino, comprising an O(1) fraction of the dark matter (DM), then it exhibits the property that its mass times mixing angle is ˜ few×10-2 eV, a plausible mass scale for the active neutrinos. This property is a common feature of Dirac neutrino mixing. We present a framework that dynamically produces light active and keV sterile Dirac neutrinos, with appropriate mixing angles to be the x-ray line source. The central idea is that the right-handed active neutrino is a composite state, while elementary sterile neutrinos gain keV masses similarly to the quarks in extended technicolor. The entire framework is fixed by just two dynamical scales and may automatically exhibit a warm dark matter (WDM) production mechanism—dilution of thermal relics from late decays of a heavy composite neutrino—such that the keV neutrinos may comprise an O(1) fraction of the DM. In this framework, the WDM is typically quite cool and within structure formation bounds, with temperature ˜ few×10-2T? and free-streaming length ˜ few kpc. A toy model that exhibits the central features of the framework is also presented.

  11. Identification of the 3.55-keV line within the framework of standard physics

    NASA Astrophysics Data System (ADS)

    Dubrovich, V. K.

    2014-12-01

    The identification of the X-ray 3.55-keV line as a recombination line of the ? - tritium mesoatom is proposed. The formation of such an atom under standard astrophysical conditions without invoking new physics is shown to be possible in principle.

  12. PeV Neutrinos and a 3.5 keV X-Ray Line from a PeV Scale Supersymmetric Neutrino Sector

    E-print Network

    Roland, Samuel B; Wells, James D

    2015-01-01

    Recent measurements of PeV energy neutrinos at IceCube and a 3.5 keV X-ray line in the spectra of several galaxies are both tantalizing signatures of new physics. This paper shows that one or both of these observations can be explained within an extended supersymmetric neutrino sector. Obtaining light active neutrino masses as well as phenomenologically interesting (keV-GeV) sterile neutrino masses without any unnaturally small parameters hints at a new symmetry in the neutrino sector that is broken at the PeV scale, presumably tied to supersymmetry breaking. The same symmetry and structure can sufficiently stabilize an additional PeV particle, produce its abundance through the freeze-in mechanism, and lead to decays that can give the energetic neutrinos observed by IceCube. The lightest sterile neutrino, if at 7 keV, is a non-resonantly produced fraction of dark matter, and can account for the 3.5 keV X-ray line. The two signals could therefore be the first probes of an extended supersymmetric neutrino secto...

  13. On the 110 keV Feature From A0535+26: Direct Evidence For A Near-Critical Magnetic Field

    E-print Network

    Rafael A. Araya; Alice K. Harding

    1996-03-15

    A recent high resolution measurement of an absorption line at 110 keV in the phase-averaged spectrum of A0535+26 (Grove et al. 1994) and the conspicuous absence of a previously reported harmonic feature at around 50 keV (Kendziorra et al. 1992, 1994) are indicative of cyclotron scattering in a magnetic field of about $10^{13}$G. However, controversy has risen over whether a lower field scenario may account for the alleged absence or weakness of a lower energy fundamental harmonic feature. This work explores these two alternatives through the generation of theoretical cyclotron spectra. For lower field models, a cylindrical geometry of the line forming region and the strong angle dependence of the cross section for resonant scattering conspire to fill in a first harmonic at around 57 keV. Higher field models (B $\\simeq$ 10.75 TG), however, yield significantly better fits (${\\cal X}^2_{low}/{\\cal X}^2_{high} \\sim 71$), thus strengthening the case for a near-critical field ($B_{crit} \\simeq 44$ TG). Phase-resolved OSSE spectra are not yet available but would greatly help in resolving this issue.

  14. 3.55Â keV photon line and its morphology from a 3.55Â keV axionlike particle line

    NASA Astrophysics Data System (ADS)

    Cicoli, Michele; Conlon, Joseph P.; Marsh, M. C. David; Rummel, Markus

    2014-07-01

    Galaxy clusters can efficiently convert axionlike particles (ALPs) to photons. We propose that the recently claimed detection of a 3.55-3.57 keV line in the stacked spectra of a large number of galaxy clusters and the Andromeda galaxy may originate from the decay of either a scalar or fermionic 7.1 keV dark matter species into an ALP of mass ma?6×10-11 eV, which subsequently converts to a photon in the cluster magnetic field. In contrast to models in which the photon line arises directly from dark matter decay or annihilation, this can explain the anomalous line strength in the Perseus cluster. As cool-core clusters have high central magnetic fields and axion-photon conversion scales as B2, this model can also explain the observed peaking of the line emission in the cool cores of the Perseus, Ophiuchus, and Centaurus clusters, as opposed to the much larger dark matter halos. We describe distinctive predictions of this scenario for future observations.

  15. Discovery of a 3.5 keV line in the Galactic Centre and a critical look at the origin of the line across astronomical targets

    NASA Astrophysics Data System (ADS)

    Jeltema, Tesla; Profumo, Stefano

    2015-06-01

    We examine the claimed excess X-ray line emission near 3.5 keV including both a new analysis of XMM-Newton observations of the Milky Way centre and a reanalysis of the data on M 31 and clusters. In no case do we find conclusive evidence for an excess. In the case of the Galactic Centre, we show that known plasma lines, including in particular K XVIII lines at 3.48 and 3.52 keV, provide a satisfactory fit to the XMM data. We estimate the expected flux of the K XVIII lines and find that the measured line flux falls squarely within the predicted range based on the brightness of other well-measured lines in the energy range of interest and on detailed multitemperature plasma models. We then re-assess the evidence for excess emission from clusters of galaxies, allowing for systematic uncertainty in the expected flux from known plasma lines and additional uncertainty due to potential variation in the abundances of different elements. We find that no conclusive excess line emission can be advocated when considering systematic uncertainties in Perseus or in other clusters. We also reanalyse the XMM data for M 31 and find no statistically significant line emission near 3.5 keV to a level greater than 1?. Finally, we analyse the Tycho supernova remnant, which shows similar plasma features to the sources above, but does not host any significant dark matter. We detect a 3.55 keV line from Tycho, which points to possible systematic effects in the flux determination of weak lines, or to relative elemental abundances vastly different from theoretical expectations.

  16. Measurement of the -3 keV resonance in the reaction 13C(?,n)16O of importance in the s-process.

    PubMed

    La Cognata, M; Spitaleri, C; Trippella, O; Kiss, G G; Rogachev, G V; Mukhamedzhanov, A M; Avila, M; Guardo, G L; Koshchiy, E; Kuchera, A; Lamia, L; Puglia, S M R; Romano, S; Santiago, D; Spartà, R

    2012-12-01

    The (13)C(?,n)(16)O reaction is the neutron source for the main component of the s-process, responsible for the production of most nuclei in the mass range 90energy interval where the (13)C(?,n)(16)O is effective from 140 to 230 keV. In this region, the astrophysical S(E)-factor is dominated by the -3 keV subthreshold resonance due to the 6.356 MeV level in (17)O, giving rise to a steep increase of the S(E)-factor. Notwithstanding that it plays a crucial role in astrophysics, no direct measurements exist inside the s-process energy window. The magnitude of its contribution is still controversial as extrapolations, e.g., through the R matrix and indirect techniques, such as the asymptotic normalization coefficient (ANC), yield inconsistent results. The discrepancy amounts to a factor of 3 or more right at astrophysical energies. Therefore, we have applied the Trojan horse method to the (13)C((6)Li,n(16)O)d quasifree reaction to achieve an experimental estimate of such contribution. For the first time, the ANC for the 6.356 MeV level has been deduced through the Trojan horse method as well as the n-partial width, allowing to attain an unprecedented accuracy in the (13)C(?,n)(16)O study. Though a larger ANC for the 6.356 MeV level is measured, our experimental S(E)-factor agrees with the most recent extrapolation in the literature in the 140-230 keV energy interval, the accuracy being greatly enhanced thanks to this innovative approach. PMID:23368189

  17. Search for 14.4 keV solar axions from M1 transition of Fe-57 with CUORE crystals

    E-print Network

    The Cuore Collaboration; F. Alessandria; R. Ardito; D. R. Artusa; F. T. Avignone III; O. Azzolini; M. Balata; T. I. Banks; G. Bari; J. Beeman; F. Bellini; A. Bersani; M. Biassoni; T. Bloxham; C. Brofferio; C. Bucci; X. Z. Cai; L. Canonica; S. Capelli; L. Carbone; L. Cardani; M. Carrettoni; N. Casali; N. Chott; M. Clemenza; C. Cosmelli; O. Cremonesi; R. J. Creswick; I. Dafinei; A. Dally; V. Datskov; A. De Biasi; M. P. Decowski; M. M. Deninno; S. Di Domizio; M. L. di Vacri; L. Ejzak; R. Faccini; D. Q. Fang; H. A. Farach; E. Ferri; F. Ferroni; E. Fiorini; M. A. Franceschi; S. J. Freedman; B. K. Fujikawa; A. Giachero; L. Gironi; A. Giuliani; J. Goett; P. Gorla; C. Gotti; E. Guardincerri; T. D. Gutierrez; E. E. Haller; K. Han; K. M. Heeger; H. Z. Huang; R. Kadel; K. Kazkaz; G. Keppel; L. Kogler; Yu. G. Kolomensky; D. Lenz; Y. L. Li; C. Ligi; X. Liu; Y. G. Ma; C. Maiano; M. Maino; M. Martinez; R. H. Maruyama; N. Moggi; S. Morganti; T. Napolitano; S. Newman; S. Nisi; C. Nones; E. B. Norman; A. Nucciotti; F. Orio; D. Orlandi; J. L. Ouellet; M. Pallavicini; V. Palmieri; L. Pattavina; M. Pavan; M. Pedretti; G. Pessina; S. Pirro; E. Previtali; V. Rampazzo; F. Rimondi; C. Rosenfeld; C. Rusconi; S. Sangiorgio; N. D. Scielzo; M. Sisti; A. R. Smith; L. Taffarello; M. Tenconi; W. D. Tian; C. Tomei; S. Trentalange; G. Ventura; M. Vignati; B. S. Wang; H. W. Wang; C. A. Whitten Jr.; T. Wise; A. Woodcraft; L. Zanotti; C. Zarra; B. X. Zhu; S. Zucchelli

    2013-04-26

    We report the results of a search for axions from the 14.4 keV M1 transition from Fe-57 in the core of the sun using the axio-electric e?ect in TeO2 bolometers. The detectors are 5x5x5 cm3 crystals operated at about 10 mK in a facility used to test bolometers for the CUORE experiment at the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 43.65 kg d of data was made using a newly developed low energy trigger which was optimized to reduce the detectors energy threshold. An upper limit of 0.63 c kg-1 d-1 was established at 95% C.L.. From this value, a lower bound at 95% C.L. was placed on the Peccei-Quinn energy scale of fa >= 0.76 10**6 GeV for a value of S=0.55 for the flavor-singlet axial vector matrix element. Bounds are given for the interval 0.15 < S < 0.55.

  18. Measurements of the neutron-proton and neutron-carbon total cross section from 150 to 800 keV

    E-print Network

    Daub, B. H.

    There have been very few measurements of the total cross section for np scattering below 500 keV. To differentiate among NN potential models, improved cross section data between 20 and 600 keV are required. We measured the ...

  19. Fission cross-section measurements of sup 247 Cm, sup 254 Es, and sup 250 Cf from 0. 1 eV to 80 keV

    SciTech Connect

    Danon, Y.; Slovacek, R.E.; Block, R.C. (Rensselaer Polytechnic Inst., Dept. of Nuclear Engineering and Engineering Physics, Gaerttner Linac Lab., Troy, NY (US)); Lougheed, R.W.; Hoff, R.W. (Lawrence Livermore National Lab., Livermore, CA (US)); Moore, M.S. (Los Alamos National Lab., Los Alamos, NM (US))

    1991-12-01

    This paper reports on the fission cross sections of {sup 247}Cm, {sup 254}Es, and {sup 250}Cf that are measured with the Rensselaer intense neutron spectrometer from 0.1 eV to 80 keV. The cross sections are normalized to the {sup 235}U ENDF/B-V broadened cross section. Fission areas and resonance widths are determined for low-energy resonances in {sup 247}Cm. The {sup 254}Es and {sup 250}Cf fission cross sections are the only reported measurements for these isotopes. The {sup 254}Es isotope is the heaviest odd- odd isotope ever measured over this energy range. The thermal fission cross sections for {sup 247}Cm, {sup 254}Es, and {sup 250}Cf are determined by extrapolation of the low-energy region of the cross section and are in good agreement with other reported measurements. Resonance integrals are reported for the energy range of 0.1 eV to 80 keV, and the areas for {sup 247}Cm and {sup 250}Cf resonances are also reported. The previously reported {sup 246}Cm fission cross section was corrected for fission in {sup 247}Cm.

  20. Observation of the 40 keV field-aligned ion beams

    NASA Astrophysics Data System (ADS)

    Sheldon, R. B.; Spence, H. E.; Fennell, J. F.

    Recent observations by CEPPAD/IPS from the new perspective of the POLAR orbit reveal a close association of field-aligned ionospheric beams with convecting plasmasheet “nose” ions. April 15, 1996 was marked by a large southward BZ accompanying a fast solar wind shock. This event triggered a strong cross-tail convection electric field that pushed plasmasheet ions deep into the magnetosphere. When the POLAR spacecraft passed through the inner magnetosphere, it observed both an unusually energetic plasmasheet nose ion injection at ˜90 keV, as well as a peculiar field-aligned beam at ˜40 keV. These beams appear to be enriched in oxygen ions (as inferred from other instruments), which would place their origin in the ionosphere. Both populations existed from L=7-3, for a duration of at least 2 hours. We speculate that the nose ions create a parallel electric field that is responsible for the extended ionospheric beam signature.

  1. 7 keV sterile neutrino dark matter in U(1) R -lepton number model

    NASA Astrophysics Data System (ADS)

    Chakraborty, Sabyasachi; Ghosh, Dilip Kumar; Roy, Sourov

    2014-10-01

    We study the phenomenology of a keV sterile neutrino in a supersymmetric model with U(1) R -lepton number in the light of a very recent observation of an X-ray line signal at around 3.5 keV, detected in the X-ray spectra of Andromeda galaxy and various galaxy clusters including the Perseus galaxy cluster. This model not only provides a small tree level mass to one of the active neutrinos but also renders a suitable warm dark matter candidate in the form of a sterile neutrino with negligible active-sterile mixing. Light neutrino masses and mixing can be explained once one-loop radiative corrections are taken into account. The scalar sector of this model can accommodate a Higgs boson with a mass of ˜125 GeV. In this model gravitino is the lightest supersymmetric particle (LSP) and we also study the cosmological implications of this light gravitino with mass.

  2. Effect of 200 keV Ar+ implantation on optical & electrical properties of polyethyleneterepthalate (PET)

    NASA Astrophysics Data System (ADS)

    Kumar, Rajiv; Goyal, Meetika; Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu; Kanjilal, D.

    2015-05-01

    In the present paper we have discussed the effect of 200 keV Ar+ ions on the electrical and optical properties of PET samples. PET samples were implanted with 200 keV Ar+ ions to various doses ranging from 1×1015 to 1×1017 Ar+ cm2. The changes in the electrical and optical properties of pristine and implanted PET specimens have been studied by using Keithley electrometer and UV-Visible absorption spectroscopy. The electrical conductivity has found to be increased with increasing ion dose. The optical studies have revealed the drastic alterations in optical band gap from 3.63 eV to 1.48 eV and also increase in number of carbon atoms per cluster from 215 to 537. Further, the change in the electrical conductivity and optical band gap has also been correlated with the formation of conductive islands in the implanted layers of PET.

  3. Calibration of thin-film dosimeters irradiated with 80-120 kev electrons

    NASA Astrophysics Data System (ADS)

    Helt-Hansen, Jakob; Miller, Arne; McEwen, Malcolm; Sharpe, Peter; Duane, Simon

    2004-09-01

    A method for calibration of thin-film dosimeters irradiated with 80-120 keV electrons has been developed. The method is based on measurement of dose with a totally absorbing graphite calorimeter, and conversion of dose in the graphite calorimeter to dose in the film dosimeter by Monte Carlo calculations. A thermal model was developed to estimate the temperature contributions from the air above the calorimeter that is heated by the electron beam. As an example, Risø B3 thin-film dosimeters were calibrated by 80-120 keV electron irradiation and compared with a calibration carried out at 10 MeV electron irradiation. The two calibrations were found to be equal within the estimated uncertainties of ±10% at 1 s.d.

  4. Extraction system design for 50A, 50keV, 2 sec ion beam

    Microsoft Academic Search

    L. D. Stewart; R. C. Davis; T. C. Jernigan; O. B. Morgan; D. E. Schechter; W. L. Stirling

    1974-01-01

    The basic ORMAK injection unit was operated at 40 keV, 6A, 0.3 sec and a 15% duty cycle, while monitoring power loading to the various extraction system electrodes, in order to pinpoint the critical power loading areas. A 40A scaleup of this ORMAK unit is being built. Thermal time constants for these water-cooled extraction electrodes are about 0.5 sec. Going

  5. Argon ion sputtering of niobium and niobium alloys. [15 keV

    Microsoft Academic Search

    1978-01-01

    Polycrystalline niobium was irradiated by a beam of 15-keV argon ions, and the effect of certain metallurgical and environmental conditions was studied. Macroscopic sputtering yields were measured for well-annealed niobium and also for Nb--V and Nb--O alloys, cold-worked and recovered niobium and for sputtering conducted in an oxygen atmosphere. In all cases, the resulting surface topography was characterized by scanning

  6. Constraints on radiative decay of the 17-keV neutrino from COBE Measurements

    E-print Network

    Biman B. Nath

    1992-08-12

    It is shown that, for a nontrivial radiative decay channel of the 17-keV neutrino, the photons would distort the microwave background radiation through ionization of the universe. The constraint on the branching ratio of such decays from COBE measurements is found to be more stringent than that from other considerations. The limit on the branching ratio in terms of the Compton $y$ parameter is $B_\\gamma < 1.5 \\times 10^{-7} ({\\tau_\

  7. Present Status of 200 KEV Polarized Electron Gun at Nagoya University

    Microsoft Academic Search

    M. Yamamoto; N. Yamamoto; T. Nakanishi; S. Okumi; F. Furuta; M. Miyamoto; M. Kuwahara; K. Naniwa; K. Yasui; M. Kuriki; H. Matsumoto; M. Yoshioka

    2005-01-01

    A proto-type of 200 keV electron gun for a future linear collider has been constructed at Nagoya University. The degradation of a negative electron affinity (NEA) surface of a GaAs photocathode is known as a major problem for such a high field gradient gun, since the gun is required to produce the high intensity and low emittance beam. In order

  8. A large scale height galactic component of the diffuse 2-60 keV background

    NASA Technical Reports Server (NTRS)

    Iwan, D.; Marshall, F. E.; Boldt, E. A.; Mushotzky, R.; Shafer, R. A.; Stottlemyer, A.

    1982-01-01

    The diffuse 2-60 keV X-ray background has a galactic component clearly detectable by its strong variation with both galactic latitude and longitude. This galactic component is typically 10 percent of the extragalactic background toward the galactic center, half that strong toward the anticenter, and extrapolated to a few percent of the extragalactic background toward the galactic poles. It is acceptably modeled by a finite radius emission disk with a scale height of several kiloparsecs. The averaged galactic spectrum is best fitted by a thermal spectrum of kT about 9 keV, a spectrum much softer than the about 40 keV spectrum of the extragalactic component. The most likely source of this emission is low luminosity stars with large scale heights such as subdwarfs. Inverse Compton emission from GeV electrons on the microwave background contributes only a fraction of the galactic component unless the local cosmic ray electron spectrum and intensity are atypical.

  9. Quiet-time Interplanetary ˜2-20keV Superhalo Electrons at Solar Minimum

    NASA Astrophysics Data System (ADS)

    Wang, L.; Lin, R. P.; Salem, C. S.; Pulupa, M.

    2011-12-01

    The average flux of the ~2-20 keV superhalo electrons in the solar wind during quiet-time periods, measured by the Suprathermal Electron instrument onboard the two STEREO spacecraft, slowly decreases with time from 2007 to 2009 and then increases in 2010, similar to the solar cycle variation around this solar minimum. We made a comprehensive study for a 2-year period from 2007 March through 2009 March, and found that the observed quiet-time ˜2-20 keV superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f ˜ v-?, ranging from v-5 to v-8.7, with the average index of 6.69. The observed power-law spectrum varies significantly on spatial scales of >˜0.1 AU and/or temporal scale of >˜ days. There is no correlation (-0.1 < coefficient < 0.2) with the solar wind proton density, velocity and temperature, but the power-law index ? is weakly anti-correlated (coefficient -0.48) with the electron velocity distribution function at 14.8 keV. The origin of these quiet-time superhalo electrons remains unclear, but since they are present even in the absence of any solar activity, they may be due to resonant wave-particle interactions in the corona or the interplanetary space.

  10. Measurement of the 20 and 90 keV resonances in the 18O(p,alpha)15N reaction via the Trojan horse method.

    PubMed

    La Cognata, M; Spitaleri, C; Mukhamedzhanov, A M; Irgaziev, B; Tribble, R E; Banu, A; Cherubini, S; Coc, A; Crucillà, V; Goldberg, V Z; Gulino, M; Kiss, G G; Lamia, L; Mrazek, J; Pizzone, R G; Puglia, S M R; Rapisarda, G G; Romano, S; Sergi, M L; Tabacaru, G; Trache, L; Trzaska, W; Tumino, A

    2008-10-10

    The 18O(p,alpha)15N reaction is of primary importance in several astrophysical scenarios, including fluorine nucleosynthesis inside asymptotic giant branch stars as well as oxygen and nitrogen isotopic ratios in meteorite grains. Thus the indirect measurement of the low energy region of the 18O(p,alpha)15N reaction has been performed to reduce the nuclear uncertainty on theoretical predictions. In particular the strength of the 20 and 90 keV resonances has been deduced and the change in the reaction rate evaluated. PMID:18999593

  11. Earth X-ray albedo for cosmic X-ray background radiation in the 1--1000 keV band

    E-print Network

    E. Churazov; S. Sazonov; R. Sunyaev; M. Revnivtsev

    2008-02-11

    We present calculations of the reflection of the cosmic X-ray background (CXB) by the Earth's atmosphere in the 1--1000 keV energy range. The calculations include Compton scattering and X-ray fluorescent emission and are based on a realistic chemical composition of the atmosphere. Such calculations are relevant for CXB studies using the Earth as an obscuring screen (as was recently done by INTEGRAL). The Earth's reflectivity is further compared with that of the Sun and the Moon -- the two other objects in the Solar system subtending a large solid angle on the sky, as needed for CXB studies.

  12. Fission cross section measurements of Cm-247, Cf-250 and Es-254 from 0. 1 eV to 80 keV

    SciTech Connect

    Danon, Y.; Slovacek, R.E.; Block, R.C. (Rensselaer Polytechnic Inst., Troy, NY (USA). Dept. of Nuclear Engineering and Engineering Physics); Lougheed, R.W.; Hoff, R.W. (Lawrence Livermore National Lab., CA (USA)); Moore, M.S. (Los Alamos National Lab., NM (USA))

    1990-01-01

    Fission cross section measurements were made with the RINS system over the neutron energy range from approximately 0.1 eV to 80 keV upon samples of Cm-247, Cf-250 and Es-254. The Cm-247 measurement was undertaken to complete the RINS fission cross section measurement sequence of the curium isotopes, Es-254 was measured because it is a very heavy odd-odd nucleus which might show interesting nuclear structure effects in its fission cross section, and Cf-250 was measured to account for its buildup as a daughter product from the 276-day halflife Es-254. 6 refs., 3 figs.

  13. Phase space compression of low energy muon beams

    Microsoft Academic Search

    D. Taqqu

    1992-01-01

    The phase space compression method (PSC) is applied to low energy muons produced in a high magnetic field. By making use of\\u000a the existing apparatus, transverse and longitudinal PSC operations will lead to a standard low energy muon beam of energy\\u000a variable between 2 keV and 20 keV. At 5 keV the beam has ?p\\/p<5% and can be focused on

  14. Molecular dynamics simulation of radiation damage in CaCd{sub 6} quasicrystal cubic approximant up to 10 keV

    SciTech Connect

    Chen, P. H. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Science and Technology on Surface Physics and Chemistry Laboratory, P.O. Box 718-35, 621907 Mianyang (China); Avchachov, K.; Nordlund, K. [Accelerator Laboratory, University of Helsinki, P.O. Box 43, 00014 Helsinki (Finland); Pussi, K. [Department of Mathematics and Physics, Lappeenranta University of Technology, P.O. Box 20, FIN-53851 Lappeenranta (Finland)

    2013-06-21

    Due to the peculiar nature of the atomic order in quasicrystals, examining phase transitions in this class of materials is of particular interest. Energetic particle irradiation can provide a way to modify the structure locally in a quasicrystal. To examine irradiation-induced phase transitions in quasicrystals on the atomic scale, we have carried out molecular dynamics simulations of collision cascades in CaCd{sub 6} quasicrystal cubic approximant with energies up to 10 keV at 0 and 300 K. The results show that the threshold energies depend surprisingly strongly on the local coordination environments. The energy dependence of stable defect formation exhibits a power-law dependence on cascade energy, and surviving defects are dominated by Cd interstitials and vacancies. Only a modest effect of temperature is observed on defect survival, while irradiation temperature increases lead to a slight increase in the average size of both vacancy clusters and interstitial clusters.

  15. Destruction of CO ice and formation of new molecules by irradiation with 28 keV O 6+ ions

    NASA Astrophysics Data System (ADS)

    de Barros, A. L. F.; Seperuelo Duarte, E.; Farenzena, L. S.; da Silveira, E. F.; Domaracka, A.; Rothard, H.; Boduch, P.

    2011-05-01

    The effect of solar wind on cometary ice was studied by using oxygen ions with energy near to that corresponding to their maximum abundance in space for bombarding CO ice. This gas was condensed on a CsI substrate at 14 K and irradiated by 28 keV 18O 6+ ions up to a final fluence of 1.3 × 10 16 cm -2. We have used a methodology in which the sputtering yields, the destruction rate of CO, and the rate of formation of new molecular species are determined by Fourier transform infrared spectroscopy (FTIR). In the current experiment, the condensation of a thin water ice film has prevented the CO sputtering. Quantities such as the dissociation yield, Yd (the number of ice molecules destroyed or dissociated per projectile impact), and the formation yield, Yf (the number of daughter molecules of a given species formed per projectile) are found to be more appropriate and useful than using an integrated or average cross section, since the projectiles are slowing down in the ice from their initial energy until zero velocity (implantation).

  16. A CHANDRA OBSERVATION OF 3C 288-REHEATING THE COOL CORE OF A 3 keV CLUSTER FROM A NUCLEAR OUTBURST at z = 0.246

    SciTech Connect

    Lal, D. V.; Kraft, R. P.; Forman, W. R.; Jones, C.; Nulsen, P. E. J.; Evans, D. A.; Lee, J. C. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Hardcastle, M. J. [School of Physics, Astronomy, and Mathematics, University of Hertfordshire, Hatfield, AL 10 9AB (United Kingdom); Croston, J. H. [School of Physics and Astronomy, University of Southampton, Southampton, SO17 1SJ (United Kingdom)

    2010-10-20

    We present results from a 42 ks Chandra/ACIS-S observation of the transitional FR I/FR II radio galaxy 3C 288 at z = 0.246. We detect {approx}3 keV gas extending to a radius of {approx}0.5 Mpc with a 0.5-2.0 keV luminosity of 6.6 x 10{sup 43} erg s{sup -1}, implying that 3C 288 lies at the center of a poor cluster. We find multiple surface brightness discontinuities in the gas indicative of either a shock driven by the inflation of the radio lobes or a recent merger event. The temperature across the discontinuities is roughly constant with no signature of a cool core, thus disfavoring either the merger cold front or sloshing scenarios. We argue therefore that the discontinuities are shocks due to the supersonic inflation of the radio lobes. If they are shocks, the energy of the outburst is {approx}10{sup 60} erg, or roughly 30% of the thermal energy of the gas within the radius of the shock, assuming that the shocks are part of a front produced by a single outburst. The cooling time of the gas is {approx}10{sup 8} yr, so that the energy deposited by the nuclear outburst could have reheated and efficiently disrupted a cool core.

  17. Theoretical Investigation of Transmission-Type Phase Shifter Made with Muscovite Mica Crystal for 1-keV Region

    NASA Astrophysics Data System (ADS)

    Imazono, Takashi; Koike, Masato

    2007-01-01

    In a soft x-ray region from 0.7 keV to 1.1 keV, the performance of transmission-type phase shifter was investigated theoretically based on the dynamical theory. As the result it was found that natural muscovite, KAl2(AlSi3O10)(OH)2, could be used as phase shifters in both symmetric Bragg and Laue geometries. In particular, the muscovite(002) having 5 ?m thickness in Laue geometry showed a phase retardation of ˜±90° and a transmittance of ˜0.02% at 0.88 keV.

  18. Development of the EXITE detector - A new imaging detector for 20 - 300 keV astronomy. [Energetic X-ray Imaging Telescope Experiment

    NASA Technical Reports Server (NTRS)

    Garcia, M. R.; Grindlay, J. E.; Burg, R.; Murray, S. S.; Flanagan, J.

    1986-01-01

    The development and testing of a detector to be used in the Energetic X-ray Imaging Telescope Experiment (EXITE) are reported. It consists of a 34 cm diameter NaI(Tl) crystal coupled directly to a single large image intensifier tube with associated silicon PIN diode readout. The measured spatial and energy resolutions at 122 keV are 6mm (FWHM) and 9 percent (FWHM), respectively. This energy resolution is about 50 percent better than that of any previously flown hard X-ray experiment. These resolutions decrease with the square root of the energy of the incident X-ray, indicating that they are determined by the number of photons emitted in the NaI(Tl) scintillator light flash.

  19. Study and implementation of a soft X-ray 100 eV -20 keV fixed exit monochromator system

    NASA Astrophysics Data System (ADS)

    Pelliciari, C.; Barbera, M.; Candia, R.; Collura, A.; Di Cicca, G.; Pareschi, G.; Varisco, S.

    2006-06-01

    We describe a "built in house" X-ray monochromator which produces a fixed exit X-ray beam tunable in the full energy range 0.1 - 20 keV. The system is based on a double diffraction on two large size parallel crystals positioned using a remotely controlled micropositioning system in order to keep the position of the monochromatic beam for any chosen energy. Up to six different diffracting elements can be selected without breaking the vacuum. This allows to cover the full energy range of interest. The system is part of an upgrading project of the XACT facility at the Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Palermo G.S. Vaiana, and will be employed for the testing and calibration of filters, detectors and optics at X-ray wavelengths.

  20. 3291keV Jpi=252+ level in 205T1

    Microsoft Academic Search

    J. A. Becker; R. G. Lanier; L. G. Mann; G. L. Struble; K. H. Maier; L. E. Ussery; W. Stöffl; T. W. Nail; R. K. Sheline; J. A. Cizewski; B. H. Erkkila; J. Blomqvist

    1984-01-01

    A Jpi=252+ isomer in 205T1 has been observed using techniques of in-beam gamma-ray spectroscopy and the 204Hg(t,2n)205T1 reaction. The decay scheme firmly establishes the yrast levels: [Jpi,Ex (keV)] 112-, 1484.02; 152-, 2054.57; 172-, 2394.18; 192-, 2551.56; and 252+, 3290.7. A candidate for a 12- state in 204T1 with the configuration (pih112-1,nui132-1) is identified.

  1. ABRIXAS, an imaging telescope for a 0.5-10 keV survey.

    NASA Astrophysics Data System (ADS)

    Friedrich, P.; Hasinger, G.; Richter, G.; Fritze, K.; Trümper, J.; Bräuninger, H.; Predehl, P.; Staubert, R.; Kendziorra, E.

    1996-02-01

    In cooperation with DARA the authors are planning the small X-ray satellite mission ABRIXAS (A Broadband Imaging X-ray All-sky Survey), extending the ROSAT survey to the harder X-ray band (0.5-10 keV) with an angular resolution better than 1'. As a pathfinder mission, ideally before XMM and AXAF, it can pinpoint objects obscured for soft X-rays by absorbing gas and dust. Its main goal is to study the absorbed AGN population and its contribution to the X-ray background.

  2. 3.55 keV line in Minimal Decaying Dark Matter scenarios

    E-print Network

    Giorgio Arcadi; Laura Covi; Federico Dradi

    2014-12-19

    We investigate the possibility of reproducing the recently reported $3.55\\,\\mbox{keV}$ line in some simple decaying dark matter scenarios. In all cases a keV scale decaying DM is coupled with a scalar field charged under SM gauge interactions and thus capable of pair production at the LHC. We will investigate how the demand of a DM lifetime compatible with the observed signal, combined with the requirement of the correct DM relic density through the freeze-in mechanism, impacts the prospects of observation at the LHC of the decays of the scalar field.

  3. Differential cross sections for single ionization of H2 by 75keV proton impact

    NASA Astrophysics Data System (ADS)

    Chowdhury, U.; Schulz, M.; Madison, D. H.

    2012-11-01

    We have calculated Triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H2 by 75 keV proton impact using the molecular 3 body distorted wave Eikonal initial state (M3DW-EIS) approach. Previously published measured DDCS-P (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles which were interpreted as an interference resulting from the two-centered potential of the molecule.

  4. On the 511 keV emission line of positron annihilation in the Milky Way

    E-print Network

    N. Prantzos

    2008-09-15

    I review our current understanding of positron sources in the Galaxy, on the basis of the reported properties of the observed 511 keV annihilation line. It is argued here that most of the disk positrons propagate away from the disk and the resulting low surface brightness annihilation emission is currently undetectable by SPI/INTEGRAL. It is also argued that a large fraction of the disk positrons may be transported via the regular magnetic field of the Galaxy into the bulge and annihilate there. These ideas may alleviate current difficulties in interepreting INTEGRAL results in a "conventional" framework.

  5. Kinematically complete experiment on single ionization in 75-keV p+He collisions

    SciTech Connect

    Schulz, M.; Maydanyuk, N. V.; Foster, M.; Tooke, B.; Madison, D. H. [University of Missouri-Rolla, Physics Department and Laboratory for Atomic, Molecular, and Optical Research, Rolla, Missouri 65409 (United States); Hasan, A. [University of Missouri-Rolla, Physics Department and Laboratory for Atomic, Molecular, and Optical Research, Rolla, Missouri 65409 (United States); Department of Physics, UAE University, P.O. Box 17551, Alain, Abu Dhabi (United Arab Emirates)

    2006-06-15

    We have measured and calculated fully differential single-ionization cross sections for the complete three-dimensional space in 75 keV p+He collisions. Several signatures of the projectile-residual-target-ion interaction, some of which are not observable for fast projectiles and for electron impact, are revealed. Some of these features are qualitatively reproduced by our calculations if this interaction is accounted for. However, overall the agreement between theory and experiment is not very good. Thus, our understanding of effects caused by the projectile-residual-target-ion interaction appears to be rather incomplete.

  6. 60 keV Ar?-ion induced modification of microstructural, compositional, and vibrational properties of InSb

    SciTech Connect

    Datta, D. P.; Garg, S. K.; Som, T., E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Bhubaneswar, Odisha 751005 (India); Satpati, B. [Surface Physics and Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Sahoo, P. K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751005, Odisha (India); Kanjilal, A. [Department of Physics, Shiv Nadar University, Uttar Pradesh 203207 (India); Dhara, S. [Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2014-10-14

    Room temperature irradiation of InSb(111) by 60 keV Ar?-ions at normal (0°) and oblique (60°) angles of incidence led to the formation of nanoporous structure in the high fluence regime of 1×10¹? to 3×10¹? ions cm?². While a porous layer comprising of a network of interconnected nanofibers was generated by normal ion incidence, evolution of plate-like structures was observed for obliquely incident ions. Systematic studies of composition and structure using energy dispersive x-ray spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Raman mapping, grazing incidence x-ray diffraction, and cross-sectional transmission electron microscopy revealed a high degree of oxidation of the ion-induced microstructures with the presence of In?O? and Sb?O? phases and presence of nanocrystallites within the nanoporous structures. The observed structural evolution was understood in terms of processes driven by ion-induced defect accumulation within InSb.

  7. Cross-field diffusion of energetic (100 keV to 2 MeV) protons in interplanetary space

    SciTech Connect

    Costa Jr, Edio da [Instituto Federal de Minas Gerais-IFMG, Ouro Preto, MG, 35400-000 (Brazil); Tsurutani, Bruce T. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Alves, Maria Virgínia; Echer, Ezequiel [Instituto Nacional de Pesquisas Espaciais-INPE, São José dos Campos, SP, 12227-010 (Brazil); Lakhina, Gurbax S., E-mail: edio.junior@ifmg.edu.br, E-mail: costajr.e@gmail.com [Indian Institute for Geomagnetism, Navi Mumbai 410 218 (India)

    2013-12-01

    Magnetic field magnitude decreases (MDs) are observed in several regions of the interplanetary medium. In this paper, we characterize MDs observed by the Ulysses spacecraft instrumentation over the solar south pole by using magnetic field data to obtain the empirical size, magnetic field MD, and frequency of occurrence distribution functions. The interaction of energetic (100 keV to 2 MeV) protons with these MDs is investigated. Charged particle and MD interactions can be described by a geometrical model allowing the calculation of the guiding center shift after each interaction. Using the distribution functions for the MD characteristics, Monte Carlo simulations are used to obtain the cross-field diffusion coefficients as a function of particle kinetic energy. It is found that the protons under consideration cross-field diffuse at a rate of up to ?11% of the Bohm rate. The same method used in this paper can be applied to other space regions where MDs are observed, once their local features are well known.

  8. Photon-induced L X-ray production differential cross sections in thorium at 22.6 keV

    NASA Astrophysics Data System (ADS)

    Puri, Sanjiv; Mehta, D.; Shahi, J. S.; Garg, M. L.; Singh, Nirmal; Trehan, P. N.

    1999-04-01

    The Ll, L?, L? 2,4, L? 1,3 and L? 1,5 X-ray production differential cross sections in 90Th have been measured at 22.6 keV incident photon energy in an angular range 50-130°. The measurements were performed using a 109Cd annular-source and a Si(Li) detector. The measured differential cross sections for various L X-rays are found to be angle-independent within experimental error. This is contrary to the strong angular-dependence of photon-induced Ll and L? X-ray production cross sections as reported by Kahlon et al. (K.S. Kahlon, H.S. Aulakh, N. Singh, R. Mittal, K.L. Allawadhi, B.S. Sood, Phys. Rev. A 43 (1991) 1455) and Ertugrul (M. Ertugrul, Nucl. Instr. and Meth. B 119 (1996) 345). Integral cross sections for production of Ll, L?, L?, L? 6, L? 2,4, L? 1,3, L? 9,10, L? 1,5 and total L? X-rays are also deduced and are found to be in good agreement with those calculated using reliable theoretical values of the L i ( i=1, 2, 3) subshell photoionisation cross sections, fluorescence yields, X-ray emission rates and Coster-Kronig transition probabilities.

  9. Set-up of an XAFS beamline for measurements between 2.4-8 keV at DORIS III

    SciTech Connect

    Welter, Edmund [Deutsches Elektronen-Synchrotron A Research Centre of the Helmholtz Association, Notkestrasse 85, D-22607 Hamburg (Germany)

    2010-06-23

    In this paper results from the commissioning phase and from first user experiments of a new EXAFS beamline at the DORIS III storage ring are presented. The bending magnet EXAFS beamline A1 underwent a complete rebuild and now covers the energy range 2.4-8 keV. A Ni-coated toroidal mirror, placed in a 2:1 focusing position and a plane mirror with one Ni coated stripe and one uncoated (SiO{sub 2}) stripe are used for effective higher harmonics suppression and focusing. The UHV-compatible fixed-exit Double Crystal Monochromator (DCM) is equipped with two Si(111) crystal pairs. The second crystal of one of the two crystal pairs is tilted by 90 deg. around the surface normal to shift the position of glitches. It allows Bragg angles between 5 deg. and 55.5 deg. and continuous scans in quick-EXAFS mode. Test measurements during the commissioning phase proved the excellent performance of the monochromator and a high quality of the XAFS spectra over the entire working range.

  10. Formation of carbon nanoclusters by implantation of keV carbon ions in fused silica followed by thermal annealing

    NASA Astrophysics Data System (ADS)

    Olivero, P.; Peng, J. L.; Liu, A.; Reichart, P.; McCallum, J. C.; Sze, J. Y.; Lau, S. P.; Tay, B. K.; Kalish, R.; Dhar, S.; Feldman, Leonard; Jamieson, David N.; Prawer, Steven

    2005-02-01

    In the last decade, the synthesis and characterization of nanometer sized carbon clusters have attracted growing interest within the scientific community. This is due to both scientific interest in the process of diamond nucleation and growth, and to the promising technological applications in nanoelectronics and quantum communications and computing. Our research group has demonstrated that MeV carbon ion implantation in fused silica followed by thermal annealing in the presence of hydrogen leads to the formation of nanocrystalline diamond, with cluster size ranging from 5 to 40 nm. In the present paper, we report the synthesis of carbon nanoclusters by the implantation into fused silica of keV carbon ions using the Plasma Immersion Ion Implantation (PIII) technique, followed by thermal annealing in forming gas (4% 2H in Ar). The present study is aimed at evaluating this implantation technique that has the advantage of allowing high fluence-rates on large substrates. The carbon nanostructures have been characterized with optical absorption and Raman spectroscopies, cross sectional Transmission Electron Microscopy (TEM), and Parallel Electron Energy Loss Spectroscopy (PEELS). Nuclear Reaction Analysis (NRA) has been employed to evaluate the deuterium incorporation during the annealing process, as a key mechanism to stabilize the formation of the clusters.

  11. Comparative Dosimetric Estimates of a 25 keV Electron Micro-beam with three Monte Carlo Codes

    SciTech Connect

    Mainardi, Enrico; Donahue, Richard J.; Blakely, Eleanor A.

    2002-09-11

    The calculations presented compare the different performances of the three Monte Carlo codes PENELOPE-1999, MCNP-4C and PITS, for the evaluation of Dose profiles from a 25 keV electron micro-beam traversing individual cells. The overall model of a cell is a water cylinder equivalent for the three codes but with a different internal scoring geometry: hollow cylinders for PENELOPE and MCNP, whereas spheres are used for the PITS code. A cylindrical cell geometry with scoring volumes with the shape of hollow cylinders was initially selected for PENELOPE and MCNP because of its superior simulation of the actual shape and dimensions of a cell and for its improved computer-time efficiency if compared to spherical internal volumes. Some of the transfer points and energy transfer that constitute a radiation track may actually fall in the space between spheres, that would be outside the spherical scoring volume. This internal geometry, along with the PENELOPE algorithm, drastically reduced the computer time when using this code if comparing with event-by-event Monte Carlo codes like PITS. This preliminary work has been important to address dosimetric estimates at low electron energies. It demonstrates that codes like PENELOPE can be used for Dose evaluation, even with such small geometries and energies involved, which are far below the normal use for which the code was created. Further work (initiated in Summer 2002) is still needed however, to create a user-code for PENELOPE that allows uniform comparison of exact cell geometries, integral volumes and also microdosimetric scoring quantities, a field where track-structure codes like PITS, written for this purpose, are believed to be superior.

  12. X-radiation (E > 10keV), H? and microwave emission during the impulsive phase of solar flares

    Microsoft Academic Search

    Joan A. Vorpahl

    1972-01-01

    A study has been made of the variation in hard (E? 10 keV) X-radiation, Ha and microwave emission during the impulsive phase of solar flares. Analysis shows that the rise-time in the 20–30-keV X-ray spike depends on the electron hardness, i.e., trise ~ exp (0.87 d). The impulsive phase is also marked by an abrupt, very intense increase in Ha

  13. The origin of the “local” ¼ keV X-ray flux

    NASA Astrophysics Data System (ADS)

    Uprety, Youaraj; Chiao, Meng; Collier, Michael; Cravens, Thomas; Galeazzi, Massimiliano; Koutroumpa, Dimitra; Kuntz, K. D.; Lallement, Rosine; Lepri, Susan T.; Liu, Wenhao; McCammon, Dan; Morgan, Kelsey; Porter, Frederick Scott; Puspitarini, Lucky; Robertson, Ina; Snowden, Steven L.; Thomas, Nicholas Evan; Ursino, Eugenio; Walsh, Brian R.

    2014-08-01

    The Solar Wind interacts with interstellar neutrals via charge exchange producing a spatially and temporally varying x-ray flux difficult to separate from other diffuse sources. The Diffuse X-rays from the Local Galaxy (DXL) mission measured the spatial signature of Solar Wind Charge eXchange (SWCX) emission using 2 large-area proportional counters. DXL was able to separate the SWCX contribution from the more dominant flux originating in the Local Hot Bubble. The data from the mission provide a robust estimate of the SWCX contribution to the RASS data in the ¼ keV band, showing that the total SWCX contribution is 40%±5% (stat) ±5% (sys) of the minimal ¼ keV flux in the Galactic plane. This result implies that the measured fluxes are dominated by interstellar emission, strengthening the idea of a hot bubble filling the cavity in the local interstellar medium extending ~50-150 pc from the Sun. Combined with recent three-dimensional maps of the local interstellar medium and Voyager measurements of the magnetic field outside the heliosphere, it also leads to a consistent picture of the local interstellar environment.

  14. Emission Lines between 1 and 2 keV in Cometary X-Ray Spectra

    NASA Astrophysics Data System (ADS)

    Ewing, Ian; Christian, Damian J.; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M.; Wolk, Scott J.

    2013-01-01

    We present the detection of new cometary X-ray emission lines in the 1.0-2.0 keV range using a sample of comets observed with the Chandra X-Ray Observatory and ACIS spectrometer. We have selected five comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model. Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV which we identify as being created by SWCX lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to be included in SWCX models. The silicon lines in the 1700-2000 eV range are detected for all comets, but with the rising background and decreasing cometary emission, we caution that these detections need further confirmation with higher resolution instruments.

  15. On the Origin of the 511 keV Emission in the Galactic Centre

    E-print Network

    Reba M. Bandyopadhyay; Joseph Silk; James E. Taylor; Thomas J. Maccarone

    2008-10-20

    Diffuse 511 keV line emission, from the annihilation of cold positrons, has been observed in the direction of the Galactic Centre for more than 30 years. The latest high-resolution maps of this emission produced by the SPI instrument on INTEGRAL suggest at least one component of the emission is spatially coincident with the distribution of ~70 luminous, low-mass X-ray binaries detected in the soft gamma-ray band. The X-ray band, however, is generally a more sensitive probe of X-ray binary populations. Recent X-ray surveys of the Galactic Centre have discovered a much larger population (>4000) of faint, hard X-ray point sources. We investigate the possibility that the positrons observed in the direction of the Galactic Centre originate in pair-dominated jets generated by this population of fainter accretion-powered X-ray binaries. We also consider briefly whether such sources could account for unexplained diffuse emission associated with the Galactic Centre in the microwave (the WMAP `haze') and at other wavelengths. Finally, we point out several unresolved problems in associating Galactic Centre 511 keV emission with the brightest X-ray binaries.

  16. keV scalar dark matter and the anomalous extragalactic x-ray spectrum

    NASA Astrophysics Data System (ADS)

    Babu, K. S.; Mohapatra, Rabindra N.

    2014-06-01

    We present a simple model for a 7 keV scalar dark matter particle which also explains the recently reported anomalous peak in the extragalactic x-ray spectrum at 3.55 keV in terms of its two photon decay. The model is arguably the simplest extension of the Standard Model, with the addition of a real scalar gauge singlet field subject to a reflection symmetry. This symmetry breaks spontaneously at a temperature of order few GeV which triggers the decay of the dark matter particle into two photons. In this framework, the Higgs boson of the Standard Model is also the source of dark matter in the Universe. The model fits the relic dark matter abundance and the partial lifetime for two photon decay, while being consistent with constraints from domain wall formation and dark matter self-interactions. We show that all these features of the model are preserved in its natural embedding into a simple dark U(1) gauge theory with a Higgs mechanism. The properties of the dark photon get determined in such a scenario. High precision cosmological measurements can potentially test these models, as there are residual effects from domain wall formation and non-negligible self-interactions of dark matter.

  17. The 16 August 1997 Novaya Zemlya seismic event as viewed from GSN stations KEV and KBS

    SciTech Connect

    Hartse, H.E.

    1997-11-01

    Using current and historic seismic records from Global Seismic Network stations KEV and KBS, the authors find that S minus P arrival time comparisons between nuclear explosions and the 16 August 1997 seismic event (m{sub b} {approx} 3.6) from near Novaya Zemlya clearly indicate that (relative to KEV) the 16 August event occurred at least 80 km east of the Russian test site. Including S minus P arrival times from KBS constrains the location to beneath the Kara Sea and in good agreement with previously reported locations, over 100 km southeast of the test site. From an analysis of P{sub n}/S{sub n} waveform ratios at frequencies above 4 Hz, they find that the 16 August event falls within the population of regional earthquakes and is distinctly separated from Novaya Zemlya and other northern Eurasian nuclear explosion populations. Thus, given its location and waveform characteristics, they conclude the 16 August event was an earthquake. The 16 August event was not detected at teleseismic distances, and thus, this event provides a good example of the regional detection, location, and identification efforts that will be required to monitor the Comprehensive Test Ban Treaty below m{sub b} {approx} 4.

  18. Improving accuracy and reliability of 186-keV measurements for unattended enrichment monitoring

    SciTech Connect

    Ianakiev, Kiril D [Los Alamos National Laboratory; Boyer, Brian D [Los Alamos National Laboratory; Swinhoe, Martyn T [Los Alamos National Laboratory; Moss, Calvin E [Los Alamos National Laboratory; Goda, Joetta M [Los Alamos National Laboratory; Favalli, Andrea [Los Alamos National Laboratory; Lombardi, Marcie [Los Alamos National Laboratory; Paffett, Mark T [Los Alamos National Laboratory; Hill, Thomas R [Los Alamos National Laboratory; MacArthur, Duncan W [Los Alamos National Laboratory; Smith, Morag K [Los Alamos National Laboratory

    2010-04-13

    Improving the quality of safeguards measurements at Gas Centrifuge Enrichment Plants (GCEPs), whilst reducing the inspection effort, is an important objective given the number of existing and new plants that need to be safeguarded. A useful tool in many safeguards approaches is the on-line monitoring of enrichment in process pipes. One aspect of this measurement is a simple, reliable and precise passive measurement of the 186-keV line from {sup 235}U. (The other information required is the amount of gas in the pipe. This can be obtained by transmission measurements or pressure measurements). In this paper we describe our research efforts towards such a passive measurement system. The system includes redundant measurements of the 186-keV line from the gas and separately from the wall deposits. The design also includes measures to reduce the effect of the potentially important background. Such an approach would practically eliminate false alarms and can maintain the operation of the system even with a hardware malfunction in one of the channels. The work involves Monte Carlo modeling and the construction of a proof-of-principle prototype. We will carry out experimental tests with UF{sub 6} gas in pipes with and without deposits in order to demonstrate the deposit correction.

  19. Radiation blistering in inconel-625 due to 100 keV helium ion irradiation

    NASA Astrophysics Data System (ADS)

    Whitton, J. L.; Rao, A. S.; Kaminsky, M.

    1988-05-01

    The objective of this study was to determine whether the change of angle of incidence of an ion beam impinging on surface blisters during their growth phase (before exfoliation) could influence the blister skin thickness and the blister crater depth. Polished, polycrystalline Inconel-625 samples were irradiated at room temperature and at normal incidence to the major sample surface with 100 keV helium ions to a total dose of 6.24 × 10 18 ions/cm 2. The results revealed that many exfoliated blisters leave craters which have two or three concentric pits. The blister skin thickness near the center of the blister was found to agree well with the calculated projected range of 100 keV He ions in nickel. However, the blister skin thickness of some exfoliated blisters along the edge of the fracture surface showed different thicknesses. A model is proposed to explain the observed blister crater/blister skin fracture features in terms of a change of angle of incidence of the incident ions to the surface during the growth phase of surface blisters.

  20. Single- and double-charge-exchange cross sections for Ar{sup {ital q}+}+H{sub 2} ({ital q}=6, 7, 8, 9, and 11) collisions from 6 eV to 11 keV

    SciTech Connect

    Kravis, S.; Saitoh, H.; Okuno, K.; Soejima, K.; Kimura, M.; Shimamura, I.; Awaya, Y.; Kaneko, Y.; Oura, M.; Shimakura, N. [The Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi, Saitama, 351-01 (Japan)] [The Institute of Physical and Chemical Research (RIKEN), Hirosawa 2-1, Wako-shi, Saitama, 351-01 (Japan); [Department of Physics, Tokyo Metropolitan University, Minami-Ohsawa 1-1, Hachioji-shi, Tokyo 192-03 (Japan); [Argonne National Laboratory, Argonne, Illinois 60439 (United States); [Faculty of Science, Niigata University, Niigata-shi, 950-21 (Japan)

    1995-08-01

    The cross sections for single-electron capture, including transfer ionization, and for double-electron capture, have been measured for Ar{sup {ital q}+}+H{sub 2} for {ital q}=6, 7, 8, 9, and 11 with projectile energies from {ital q} eV to {ital q} keV. Theoretically, the cross sections for Ar{sup 6+} and Ar{sup 8+} impact were calculated using a molecular-orbital expansion method in the energy region from 240 eV to 80 keV, and are in good agreement with experiment. The single-electron-capture cross sections were found to be more than one order of magnitude larger than those for double capture in both experiment and theory. The single-electron-capture cross sections were also compared to the Langevin cross section, a scaling law developed by Mueller and Salzborn [Phys. Lett. 62A, 391 (1977)], and the absorbing sphere model.

  1. Classical-trajectory Monte Carlo calculations of the electronic stopping cross section for keV protons and antiprotons impinging on hydrogen atoms

    SciTech Connect

    Custidiano, Ernesto R.; Jakas, Mario M. [Departamento de Fisica Fundamental y Experimental, Electronica y Sistemas, Universidad de La Laguna, 38205 La Laguna, Tenerife (Spain)

    2005-08-15

    Using the classical-trajectory Monte Carlo (CTMC) method, the electronic stopping cross sections of hydrogen atoms by protons and antiprotons impact are calculated. The results show that the CTMC method compares fairly well with previous quantum mechanics calculations of the stopping cross sections for the same colliding pairs. It turns out therefore that the CTMC method constitutes a reliable and, computationally speaking, convenient alternative to calculate the stopping of ions in matter. The present results also show that the stopping appears to be particularly sensitive to the angular momentum (L) of the electron orbit. In the case of protons, the highest sensitivity to L becomes evident around the energy of the maximum stopping. While for antiprotons the largest sensitivity of the stopping to L is observed down at low bombarding energies, i.e., below 10 keV.

  2. Non-abelian dark matter solutions for Galactic gamma-ray excess and Perseus 3.5 keV X-ray line

    NASA Astrophysics Data System (ADS)

    Cheung, Kingman; Huang, Wei-Chih; Sming Tsai, Yue-Lin

    2015-05-01

    We attempt to explain simultaneously the Galactic center gamma-ray excess and the 3.5 keV X-ray line from the Perseus cluster based on a class of non-abelian SU(2) DM models, in which the dark matter and an excited state comprise a ``dark'' SU(2) doublet. The non-abelian group kinetically mixes with the standard model gauge group via dimensions-5 operators. The dark matter particles annihilate into standard model fermions, followed by fragmentation and bremsstrahlung, and thus producing a continuous spectrum of gamma-rays. On the other hand, the dark matter particles can annihilate into a pair of excited states, each of which decays back into the dark matter particle and an X-ray photon, which has an energy equal to the mass difference between the dark matter and the excited state, which is set to be 3.5 keV. The large hierarchy between the required X-ray and ?-ray annihilation cross-sections can be achieved by a very small kinetic mixing between the SM and dark sector, which effectively suppresses the annihilation into the standard model fermions but not into the excited state.

  3. Measurement of the 13C(?,n)16O reaction with the Trojan horse method: Focus on the sub threshold resonance at -3 keV

    NASA Astrophysics Data System (ADS)

    La Cognata, M.; Spitaleri, C.; Trippella, O.; Kiss, G. G.; Rogachev, G. V.; Mukhamedzhanov, A. M.; Avila, M.; Guardo, G. L.; Koshchiy, E.; Kuchera, A.; Lamia, L.; Puglia, S. M. R.; Romano, S.; Santiago, D.; Spartà, R.

    2014-05-01

    The 13C(?,n)16O reaction is the neutron source of the main component of the s-process. The astrophysical S(E)-factor is dominated by the -3 keV sub-threshold resonance due to the 6.356 MeV level in 17O. Its contribution is still controversial as extrapolations, e.g., through R-matrix calculations, and indirect techniques, such as the asymptotic normalization coefficient (ANC), yield inconsistent results. Therefore, we have applied the Trojan Horse Method (THM) to the 13C(6Li,n16O)d reaction to measure its contribution. For the first time, the ANC for the 6.356 MeV level has been deduced through the THM, allowing to attain an unprecedented accuracy. Though a larger ANC for the 6.356 MeV level is measured, our experimental S(E) factor agrees with the most recent extrapolation in the literature in the 140-230 keV energy interval, the accuracy being greatly enhanced thanks to this innovative approach, merging together two well establish indirect techniques, namely, the THM and the ANC.

  4. A mass analysis technique using coincidence measurements from the Interstellar Boundary Explorer-Hi (approximately 0.3- approximately 6 keV) detector.

    PubMed

    Allegrini, F; Ebert, R W; Alquiza, J; Broiles, T; Dunn, C; McComas, D J; Silva, I; Valek, P; Westlake, J

    2008-09-01

    NASA's Interstellar Boundary Explorer (IBEX) mission, scheduled to launch in October 2008, will make the first observations of charge exchange energetic neutral atoms (ENAs) produced near the edge of the heliosphere. IBEX will measure these ENAs with two ultra-high sensitivity, single-pixel ENA sensors in the energy range of approximately 0.01- approximately 2 keV (IBEX-Lo) and approximately 0.3- approximately 6 keV (IBEX-Hi), respectively. The primary purpose of IBEX is to measure hydrogen ENAs from the outer heliosphere, but it will also be sensitive to heavier species of ENAs produced anywhere throughout the solar system. For this study, we measured the coincidence response of the IBEX-Hi detector section to H, He, N, and O ions. Based on these results, we have developed an innovative technique in estimating the hydrogen to heavy ion ratio in the signal. This new technique can be applied more widely than the IBEX-Hi detector section, and the basic principle may be useful for other, future space and ground-based measurements. PMID:19044461

  5. Reconciling naturally keV line and self interacting dark matter

    E-print Network

    Mambrini, Yann

    2015-01-01

    We show that there exists a strong correlation between monochromatic signals from annihilating dark matter and its self-interacting cross section. We apply our argument to a complex scalar dark sector, where the pseudo-scalar plays the role of the dark matter candidate while the scalar is the mediator particle. Intriguingly, we find that such an extension produces naturally a monochromatic keV signal which can correspond to recent observations of Perseus or Andromeda while in the meantime predicts self-interacting cross section of the order of $\\sigma/m \\simeq 0.1-1~\\mathrm{cm^2/g}$ measured recently in the cluster Abell 3827, without the need of invoking strong interaction or velocity enhancement. We also propose a way to distinguish such models by future direct detection techniques.

  6. Prospects for the CERN Axion Solar Telescope Sensitivity to 14.4 keV Axions

    E-print Network

    Kresimir Jakovcic; for the CAST Collaboration

    2006-11-15

    The CERN Axion Solar Telescope (CAST) is searching for solar axions using the 9.0 T strong and 9.26 m long transverse magnetic field of a twin aperture LHC test magnet, where axions could be converted into X-rays via reverse Primakoff process. Here we explore the potential of CAST to search for 14.4 keV axions that could be emitted from the Sun in M1 nuclear transition between the first, thermally excited state, and the ground state of 57Fe nuclide. Calculations of the expected signals, with respect to the axion-photon coupling, axion-nucleon coupling and axion mass, are presented in comparison with the experimental sensitivity.

  7. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    NASA Astrophysics Data System (ADS)

    Naqvi, A. A.; Al-Matouq, Faris A.; Khiari, F. Z.; Gondal, M. A.; Rehman, Khateeb-ur; Isab, A. A.; Raashid, M.; Dastageer, M. A.

    2013-11-01

    Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53-3.68, 4.51, 5.27-5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

  8. Differential cross sections for single ionization of H2 by 75-keV proton impact

    NASA Astrophysics Data System (ADS)

    Chowdhury, U.; Schulz, M.; Madison, D. H.

    2011-03-01

    We have calculated triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H2 by 75-keV proton impact using the molecular three-body distorted-wave-eikonal initial-state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles that were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H2 as atomic H multiplied by a molecular interference factor only predicts the observed structure when assumptions are made about the molecular orientation. Here we apply the M3DW-EIS method, which does not rely on such an ad hoc approach, but rather treats the interference from first principles.

  9. 511 keV line from millisecond pulsars in the Galactic center

    E-print Network

    Wei Wang

    2006-12-21

    Observations of a strong and extended positron-electron annihilation line emission in the Galactic center (GC) region by the SPI/INTEGRAL are challenging to the existing models of positron sources in the Galaxy. In this paper, we study the possibility that pulsar winds from a millisecond pulsar population in the GC produce the 511 keV line. Our preliminary estimations predict that the e+/- annihilation rate in the GC is around 5 x 10E+42 sE-1, which is consistent with the present observational constraints. Therefore, the e+/- pairs from pulsar winds can contribute significantly to the positron sources in the Galactic center region. Furthermore, since the diffusion length of positrons is short in the magnetic field, we predict that the intensity distribution of the annihilation line should follow the distribution of millisecond pulsars, which should then correlate to the mass distribution in the GC.

  10. A tip-based source of femtosecond electron pulses at 30keV

    E-print Network

    Hoffrogge, Johannes; Krüger, Michael; Förster, Michael; Hammer, Jakob; Ehberger, Dominik; Baum, Peter; Hommelhoff, Peter

    2013-01-01

    We present a nano-scale photoelectron source, optimized towards ultrashort pulse durations and well-suited for time-resolved diffraction experiments. A tungsten tip, mounted in a suppressor-extractor electrode configuration, allows the generation of 30 keV electron pulses with an estimated pulse duration of 37 fs at the gun exit. We infer the pulse duration from particle tracking simulations, which are in excellent agreement with experimental measurements of the electron-optical properties of the source. We furthermore demonstrate femtosecond laser-triggered operation. Besides the short electron pulse duration, a tip-based source is expected to feature a large transverse coherence as well as a nanometric emittance.

  11. Sputtering of cryogenic films of hydrogen by keV ions: Thickness dependence and surface morphology

    NASA Astrophysics Data System (ADS)

    Schou, Jørgen; Hilleret, Noel

    2009-08-01

    The sputtering yield induced by keV hydrogen ions measured at CERN and at Risø National Laboratory for solid H 2 and D 2 at temperatures below 4.2 K decreases with increasing film thickness from about 100 × 10 15 molecules/cm 2. For a film thickness comparable to or larger than the ion range the data from Risø show a slight increase, whereas the yield from CERN continues to decrease up to very large film thicknesses, i.e. one order of magnitude larger than the ion range. The different behavior of the yield is discussed in terms of the probable growth modes of the films. The films produced at the Risø setup are quench-condensed films, while those produced at CERN are supposed to grow with large hydrogen aggregates on top of a thin bottom layer.

  12. Ion Source Development For The Proposed FNAL 750 keV Injector Upgrade

    SciTech Connect

    Bollinger, D. S. [Fermi National Accelerator Laboratory, Box 500, Batavia, IL 60543 (United States)

    2011-09-26

    Currently there is a Proposed FNAL 750 keV Injector Upgrade for the replacement of the 40 year old Fermi National Laboratory (FNAL) Cockcroft-Walton accelerators with a new ion source and 200 MHz Radio Frequency Quadruple (RFQ). The slit type magnetron being used now will be replaced with a round aperture magnetron similar to the one used at Brookhaven National Lab (BNL). Operational experience from BNL has shown that this type of source is more reliable with a longer lifetime due to better power efficiency. The current source development effort is to produce a reliable source with >60 mA of H{sup -} beam current, 15 Hz rep-rate, 100 {mu}s pulse width, and a duty factor of 0.15%. The source will be based on the BNL design along with development done at FNAL for the High Intensity Neutrino Source (HINS).

  13. Neutral beam injector for 475 keV MARS sloshing ions

    SciTech Connect

    Goebel, D.M.; Hamilton, G.W.

    1983-12-13

    A neutral beam injector system which produces 5 MW of 475 keV D/sup 0/ neutrals continuously on target has been designed. The beamline is intended to produce the sloshing ion distribution required in the end plug region of the conceptual MARS tandem mirror commercial reactor. The injector design utilizes the LBL self-extraction negative ion source and Transverse Field Focusing (TFF) accelerator to generate a long, ribbon ion beam. A laser photodetachment neutralizer strips over 90% of the negative ions. Magnetic and neutron shield designs are included to exclude the fringe fields of the end plug and provide low activation by the neutron flux from the target plasma. The use of a TFF accelerator and photodetachment neutralizer produces a total system electrical efficiency of about 63% for this design.

  14. Neutral beam injector for 475 keV MARS sloshing ions

    SciTech Connect

    Goebel, D.M.; Hamilton, G.W.

    1984-03-01

    A neutral beam injector system which produces 5 MW of 475 keV D/sup 0/ neutrals continuously on target has been designed. The beamline is intended to produce the sloshing ion distribution required in the end plug region of the conceptual MARS tandem mirror commercial reactor. The injector design utilizes the LBL self-extraction negative ion source and Transverse Field Focusing (TFF) accelerator to generate a long, ribbon ion beam. A laser photodetachment neutralizer strips over 90% of the negative ions. Magnetic and neutron shield designs are included to exclude the fringe fields of the end plug and provide low activation by the neutron flux from the target plasma. The use of a TFF accelerator and photodetachment neutralizer produce a total system electrical efficiency of about 63% for this design.

  15. Effects of 70-keV electrons on two polyarylene ether ketones

    NASA Technical Reports Server (NTRS)

    Kingsbury, Kevin B.; Hawkins, Douglas S.; Orwoll, Robert A.; Kiefer, Richard L.; Long, Sheila A. T.

    1989-01-01

    Films prepared from two polyarylene ether ketones with the repeat units -PhC(O)PhC(O)-PhOPhXPhO- where X = C(CH3)2 or CH2 and Ph = C6H4, were bombarded with 70-keV electrons. The effects of irradiation were determined from the fraction of gel formed; the intrinsic viscosities, gel permeation chromatography, and NMR spectroscopy of the soluble portion of the irradiated films; and the changes in the IR spectra of the materials. In a Charlesby-Pinner analysis of the gel fractions of the polyarylene ether ketone with the isopropylidene group, the numbers of scission and cross-linking events per 100 eV (9649 kJ/mol) absorbed were found to be small with G(S) = 0.002 and G(X) = 0.009, respectively.

  16. X-ray lines from R-parity violating decays of keV sparticles

    NASA Astrophysics Data System (ADS)

    Kolda, Christopher; Unwin, James

    2014-07-01

    If R parity is only mildly violated, then the lightest supersymmetric particle (LSP) can be stable over cosmologically time scales and still account for the dark matter relic density. We examine the possibility of generating detectable x-ray lines from R-parity violating decays of keV-scale LSP dark matter to neutrino-photon pairs. Specifically, we consider scenarios in which the LSP is a light gravitino, bino, or hidden sector photino. Potential signals are discussed in the context of recent claims of an unidentified 3.5 keV x-ray line in studies of stacked galaxy clusters. We comment on the difficulties in obtaining the observed relic density for keV-scale bino or hidden photino dark matter and some possible resolutions.

  17. Differential cross sections for single ionization of H2 by 75keV proton impact

    NASA Astrophysics Data System (ADS)

    Chowdhury, Uttam; Schulz, Michael; Madison, Don

    2011-05-01

    We have calculated Triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of by 75 KeV proton impact using the molecular 3 body distorted wave Eikonal initial state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles which were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H2 as atomic H multiplied by a molecular interference factor only predict the observed structure when assumptions are made about the molecular orientation. Here we apply the M3DW-EIS method, which does not rely on such an ad hoc approach, but rather treats the interference from first principles and we find the same structure without assuming any preferential orientations. We have calculated Triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of by 75 KeV proton impact using the molecular 3 body distorted wave Eikonal initial state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles which were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H2 as atomic H multiplied by a molecular interference factor only predict the observed structure when assumptions are made about the molecular orientation. Here we apply the M3DW-EIS method, which does not rely on such an ad hoc approach, but rather treats the interference from first principles and we find the same structure without assuming any preferential orientations. Work supported by the National Science Foundation under grant PHY-0757749

  18. keV sterile neutrino dark matter from singlet scalar decays: basic concepts and subtle features

    NASA Astrophysics Data System (ADS)

    Merle, Alexander; Totzauer, Maximilian

    2015-06-01

    We perform a detailed and illustrative study of the production of keV sterile neutrino Dark Matter (DM) by decays of singlet scalars in the early Universe. In the current study we focus on providing a clear and general overview of this production mechanism. For the first time we study all regimes possible on the level of momentum distribution functions, which we obtain by solving a system of Boltzmann equations. These quantities contain the full information about the production process, which allows us to not only track the evolution of the DM generation but to also take into account all bounds related to the spectrum, such as constraints from structure formation or from avoiding too much dark radiation. In particular we show that this simple production mechanism can, depending on the regime, lead to strongly non-thermal DM spectra which may even feature more than one peak in the momentum distribution. These cases could have particularly interesting consequences for cosmological structure formation, as their analysis requires more refined tools than the simplistic estimate using the free-streaming horizon. Here we present the mechanism including all concepts and subtleties involved, for now using the assumption that the effective number of relativistic degrees of freedom is constant during DM production, which is applicable in a significant fraction of the parameter space. This allows us to derive analytical results to back up our detailed numerical computations, thus leading to the most comprehensive picture of keV sterile neutrino DM production by singlet scalar decays that exists up to now.

  19. Sputtering of parent-like ions from large organic adsorbates on metals under keV ion bombardment

    NASA Astrophysics Data System (ADS)

    Delcorte, A.; Bertrand, P.

    1998-09-01

    Thin films of hydrocarbon molecules, unsaturated fatty acid and low molecular weight polystyrene deposited on different metal substrates (silver, copper and gold) were bombarded by 15 keV Ga ions and the secondary ions were mass- and energy-analysed by means of a time-of-flight secondary ion mass spectrometer. The samples were studied in order to evidence the effects of different substrates and coverages on the emission of the parent and cationised molecular ions, and to gain a better understanding of the large molecular ion emission processes. Ion beam degradation studies were realised for fundamental purposes too. In general, the kinetic energy distributions of metal-cationised molecules are broad in comparison with those of the parent ions, and of the smaller polystyrene fingerprint ions. In addition, the velocity distributions of the parent ions and of the metal-cationised molecules are similar. Parent ions of aromatic molecules are, on average, more energetic than those of aliphatic molecules. In the case of metal-cationised molecules, the three hypotheses of emission of a preformed complex, recombination in the selvedge and metastable decay of larger aggregates are critically reviewed in comparison with the experimental data. The recombination hypothesis cannot account for the whole set of observations. On the other hand, the very different evolutions of the parent ions and of the metal-cationised molecules in the degradation experiments cannot be explained solely in the frame of metastable decay reactions, although the kinetic energy measurements show that a significant fraction of the parent-like ions are produced in the vacuum. The augmentation of the secondary ion kinetic energy with increasing molecule size for triacontane monomers and dimers, and for silver-cationised polystyrene oligomers, is in disagreement with the sputtering by a single cascade atom, too. Finally, the discussion outlines the conditions that must be satisfied to model the experimental observations and proposes a view of the sputtering of these large molecular cations based on multiple collision processes and possible subsequent dissociation in the vacuum.

  20. Evaluation of the ²³?Pu prompt fission neutron spectrum induced by neutrons of 500 keV and associated covariances

    DOE PAGESBeta

    Neudecker, D.; Talou, P.; Kawano, T.; Smith, D. L.; Capote, R.; Rising, M. E.; Kahler, A. C.

    2015-08-01

    We present evaluations of the prompt fission neutron spectrum (PFNS) of ²³?Pu induced by 500 keV neutrons, and associated covariances. In a previous evaluation by Talou et al. 2010, surprisingly low evaluated uncertainties were obtained, partly due to simplifying assumptions in the quantification of uncertainties from experiment and model. Therefore, special emphasis is placed here on a thorough uncertainty quantification of experimental data and of the Los Alamos model predicted values entering the evaluation. In addition, the Los Alamos model was extended and an evaluation technique was employed that takes into account the qualitative differences between normalized model predicted valuesmore »and experimental shape data. These improvements lead to changes in the evaluated PFNS and overall larger evaluated uncertainties than in the previous work. However, these evaluated uncertainties are still smaller than those obtained in a statistical analysis using experimental information only, due to strong model correlations. Hence, suggestions to estimate model defect uncertainties are presented, which lead to more reasonable evaluated uncertainties. The calculated keff of selected criticality benchmarks obtained with these new evaluations agree with each other within their uncertainties despite the different approaches to estimate model defect uncertainties. The keff one standard deviations overlap with some of those obtained using ENDF/B-VII.1, albeit their mean values are further away from unity. Spectral indexes for the Jezebel critical assembly calculated with the newly evaluated PFNS agree with the experimental data for selected (n,?) and (n,f) reactions, and show improvements for high-energy threshold (n,2n) reactions compared to ENDF/B-VII.1.« less

  1. Determination of the emission probability of the 21.54 keV ? ray in the decay of 151Sm

    NASA Astrophysics Data System (ADS)

    Shen, Hongtao; He, Ming; Ruan, Xiang Dong; Dong, Kejun; Jiang, Shan

    2011-11-01

    The emission probability of the 21.54 keV ? ray in the decay of 151Sm was experimentally determined by means of the measurements of the 21.54 keV ?-ray emission rate and the activity of 151Sm with high-resolution Ge, Si(Li) ?-ray spectrometry and liquid scintillation counting (LSC), respectively. The resulting emission probability of the 21.54 keV ? ray is 0.0324% with a standard uncertainty of 0.0013% based on a quadratic summation of the uncertainty components from the measurements of the ?-ray emission rate and the activity of 151Sm. The result agrees with the latest literature value (partially theoretically based), 0.0318 ± 0.0022%, with reduced uncertainty.

  2. Under the Shadow of the Magellanic Bridge: A Measurement of the Extragalactic Background at $\\sim 0.7$~keV

    E-print Network

    Q. Daniel Wang; Taisheng Ye

    1996-08-26

    We measured the extragalactic 0.7 keV X-ray background by observing the X-ray shadow of a neutral gas cloud in the Magellanic Bridge region. Two \\rosat PSPC observations of total 104~ks were complemented by a detailed H I mapping of the cloud with both the Parkes 64~m telescope and the Australia Telescope Compact Array. From the detected anti-correlation between the observed background intensity and the \\ion{H}{1} column density of the cloud, we derived the unabsorbed extragalactic background intensity as 28 keV s^{-1} cm^{-2} keV^{-1} sr^{-1} at 0.7~keV. The 95% confidence lower limit 18 keV s^{-1} cm^{-2} keV^ {-1} sr^{-1}} is greater than the expected point-like source contribution < 14 keV s^{-1} cm^{-2} keV^{-1} sr^{-1}, constrained by the mean source spectrum together with the total background intensity in the 1-2 keV band. A significant fraction of the 0.7 keV background likely arises in a diffuse hot intergalactic medium of a few million degrees, as has been predicted in hydrodynamic simulations of cosmological structure formation.

  3. Analysis of 6.4 KEV Moessbauer Spectra Obtained with MIMOS II on MER on Cobbles at Meridiani Planum, Mars and Considerations on Penetration Depths

    NASA Technical Reports Server (NTRS)

    Fleischer, I.; Klingelhoefer, G.; Morris, R. V.; Schroder, C.; Rodionov, D.; deSouza, P.

    2008-01-01

    The miniaturized Moessbauer (MB) spectrometers MIMOS II [1] on board of the two Mars Exploration Rovers Spirit and Opportunity have obtained more than 600 spectra of more than 300 different rock and soil targets [2-7]. Both instruments have simultaneously collected 6.4 keV X-ray and 14.4 keV .-ray spectra in backscattering geometry [1]. With Spirit's MB spectrometer, 6.4 keV and 14.4 keV spectra have been obtained for all targets through sol 461. After this date, only 14.4 keV spectra were collected. With Opportunity's spectrometer, 6.4 keV and 14.4 keV spectra have been collected for all targets to date. The Fe-mineralogy of rock and soil targets at both landing sites reported to date has been exclusively extracted from 14.4 keV spectra [2-5]. The comparison of 6.4 keV and 14.4 keV spectra provides depth selective information about a sample, but interpretation is not always straightforward [8].

  4. Fission cross-section measurements of sup 247 Cm, sup 250 Cf, and sup 254 Es from 0. 1 eV to 80 keV

    SciTech Connect

    Lougheed, R.W.; Hoff, R.W. (Lawrence Livermore National Lab., CA (USA)); Moore, M.S. (Los Alamos National Lab., NM (USA)); Danon, Y.; Slovacek, R.E.; Block, R.C.

    1990-06-01

    Fission cross-section measurements were made with the RINS system in the neutron energy range from {approximately} 0.1 eV to 80 keV on samples of {sup 247}Cm, {sup 250}Cf, and {sup 254}Es. The {sup 247}Cm measurement was undertaken to complete the RINS fission cross-section measurement sequence of the curium isotopes, {sup 254}Es was measured because it is a very heavy odd-odd nucleus that might show interesting nuclear structure effects in its fission cross section, and {sup 250}Cf was measured to account for its buildup as a daughter product from the 276-day half-life {sup 254}Es.

  5. 50 keV electron-beam projection maskless lithography (PML2): results obtained with 2,500 programmable 12.5-nm sized beams

    NASA Astrophysics Data System (ADS)

    Klein, Christof; Klikovits, Jan; Szikszai, Laszlo; Platzgummer, Elmar; Loeschner, Hans

    2010-03-01

    Projection Mask-Less Lithography (PML2) is a potentially cost-effective electron multi-beam solution for the 16 nm hp ITRS technology node and beyond. First results obtained with a PML2 Testbench are presented where a programmable Aperture Plate System (APS) was used to generate ca. 2500 micrometer-sized beams which are projected onto wafer level with 200x demagnification. The APS contains CMOS electronics which allows for addressable deflection of selected beams; only non-deflected beams make it to the wafer surface to achieve 12.5 nm spot size. Beam energy (50keV) and current density (~2 A/cm2) are the same as in future PML2 production tools. Thus, the results obtained with the PML2 Testbench unambiguously prove the patterning capabilities of the PML2 technology.

  6. Fluxes of protons above 50 keV and electrons above 30 keV at approximately 35 earth radii. I - Velocity anisotropies and plasma flow in the magnetotail. II Morphology and flow patterns in the magnetotail

    NASA Technical Reports Server (NTRS)

    Roelof, E. C.; Keath, E. P.; Bostrom, C. O.; Williams, D. J.

    1976-01-01

    Imp-7 data were used to study the morphology and flow patterns of energetic proton and electron events in the magnetotail and magnetosheath at 35 earth radii. The patterns are deduced from the probability of occurrence and the spatial distribution of the events. The distribution of 50 to 200 keV proton and 30 to 90 keV electron fluxes shows that in the magnetotail (i.e., inside the magnetopause) the proton and electron events occur primarily in the plasma sheet region within plus or minus 10 earth radii of the neutral sheet; fluxes of 50- to 200-keV protons are also found in the magnetosheath, along with occasional fluxes of 30- to 90-keV electrons; the plasma sheet is well defined (at 35 earth radii) by both the proton and electron probabilities; the frequency of the electron events in the magnetotail shows a positive correlation with the geomagnetic Kp index in the dawn and dusk sectors.

  7. Diffuse 0.5-1 keV X-Rays and Nuclear Gamma-Rays from Fast Particles in the Local Hot Bubble

    E-print Network

    V. Tatischeff; R. Ramaty

    1998-07-03

    We show that interactions of fast particles with the boundary shell of the local hot bubble could make an important contribution to the 0.5-1 keV diffuse X-ray background observed with ROSAT. The bulk of these nonthermal X-rays are due to line emission from fast O ions of energies around 1 MeV/nucleon. This is the typical energy per particle in the ejecta of the supernova which is thought to have energized the bubble. We find that there is sufficient total energy in the ejecta to produce X-rays of the required intensity, subject to the details of the evolution of the fast particle population since the supernova explosion (about 3 10$^5$ years ago based on the age of the Geminga pulsar). The unequivocal signature of lines from deexcitations in fast ions is their large width ($\\delta E/E$~0.1 for O lines), which will clearly distinguishes them from X-ray lines produced in a hot plasma. If a small fraction of the total ejecta energy is converted into accelerated particle kinetic energy (>~30 MeV/nucleon), the gamma-ray line emission produced in the boundary shell of the local hot bubble could account for the recently reported COMPTEL observations of nuclear gamma-ray lines from a broad region towards the Galactic center.

  8. Direct and charge-exchange excitation processes in H+-H(1s) collisions at 1 to 7 keV

    NASA Astrophysics Data System (ADS)

    Kimura, M.; Thorson, W. R.

    1981-10-01

    We have computed direct and charge-exchange cross sections for H++H(1s)-->H++H(nl) collisions, for projectile energies 1-7 keV, using the close-coupling method with H2+ molecular states modified by electron translation factors (ETF's); switching functions recently derived analytically for exact H2+ states were used to construct ETF corrections. Basis sets with up to 10 molecular states were used in systematic calculations, and good convergence is found for all atomic cross sections with n<=2. Results have been compared with other theoretical calculations [especially that of Crothers and Hughes (1978-1979)] and with recent experiments. Where differences between our results and those of Crothers and Hughes are found, our results agree more closely with experiment. The most notable case is the H(2s) charge-exchange (and direct) cross sections, where our results show no minimum whatever near E=2-4 keV, in agreement with experiments of Morgan et al. (1980) and Hill et al. (1979), but in strong disagreement with the calculations of Crothers and Hughes and 1969 experiments of Bayfield. In one case discrepancies between our results and those of Crothers and Hughes can be shown to arise from their treatment of ETF effects (using a different switching function for the 2p?u state)-i.e., they obtain a much larger population of the 4f?u state than is found here. We have also carried out selected studies with larger basis sets (up to 16u states) to examine the behavior of cross sections for excitation to atomic levels with n>=3. These studies strongly suggest that a "ladder-climbing" sequence of excitations via upper levels is the dominant process by which ionization occurs in H+-H(1s) collisions at these energies.

  9. Dielectric laser acceleration of 28 keV electrons with the inverse Smith-Purcell effect

    NASA Astrophysics Data System (ADS)

    Breuer, John; Hommelhoff, Peter

    2014-03-01

    Dielectric laser acceleration exploiting the large optical field strength of short laser pulses and the proximity of a dielectric structure can support high acceleration gradients may therefore lead to much smaller accelerators, with future potential application in table-top free electron lasers. We report a proof-of-concept experiment demonstrating dielectric laser acceleration of non-relativistic 28 keV electrons derived from a conventional scanning electron microscope column at a single fused-silica grating. The electrons pass the grating as closely as 50 nm and interact with the third spatial harmonic, which is excited by 110 fs long 800 nm laser pulses with a peak electric field of 2.85 GV/m. The observed maximum acceleration gradient of 25 MeV/m is already comparable to state-of-the-art radio-frequency structures. This work thus represents a demonstration of scalable laser acceleration and of the inverse Smith-Purcell effect in the optical regime. For relativistic electrons and otherwise identical conditions up to two orders of magnitude larger acceleration gradients are expected.

  10. The Relation Between Lightning and Isolated Impulsive >30 keV Electron Precipitation Events

    NASA Astrophysics Data System (ADS)

    McCarthy, M.; Bowers, G. S.; Holzworth, R. H., II; Millan, R. M.

    2014-12-01

    Isolated impulsive (few seconds time scale) magnetospheric losses of >30 keV electrons to the upper atmosphere have been inferred from bremsstrahlung observations on stationary stratospheric balloon platforms. As a first step to understanding the mechanism for this phenomenon, we address the question: what is the relation between impulsive electron precipitation events and lightning strokes? Two recent developments permit progress on this question, global lightning location networks that precisely locate and time lightning strokes, and the BARREL mission's acquisition of over 9000 hours of stratospheric bremsstrahlung observations. The analysis consists of identifying impulsive electron precipitation events in BARREL's bremsstrahlung record and relating those to immediately prior lightning strokes, with consideration for lightning network detection efficiency. A strong relation between impulsive precipitation events and lightning implies a primary role of the previously studied lightning-induced electron precipitation phenomenon. A weak relation implies another unrecognized mechanism is responsible for these isolated impulsive events. Understanding the conditions, mechanisms, and extent of isolated impulsive electron loss events is a part of an overall goal to comprehend magnetospheric trapped electron population variability.

  11. Nonabelian dark matter models for 3.5 keV X-rays

    E-print Network

    James M. Cline; Andrew R. Frey

    2014-08-06

    A recent analysis of XXM-Newton data reveals the possible presence of an X-ray line at approximately 3.55 keV, which is not readily explained by known atomic transitions. Numerous models of eV-scale decaying dark matter have been proposed to explain this signal. Here we explore models of multicomponent nonabelian dark matter with typical mass ~ 1-10 GeV (higher values being allowed in some models) and eV-scale splittings that arise naturally from the breaking of the nonabelian gauge symmetry. Kinetic mixing between the photon and the hidden sector gauge bosons can occur through a dimension-5 or 6 operator. Radiative decays of the excited states proceed through transition magnetic moments that appear at one loop. The decaying excited states can either be primordial or else produced by upscattering of the lighter dark matter states. These models are significantly constrained by direct dark matter searches or cosmic microwave background distortions, and are potentially testable in fixed target experiments that search for hidden photons. We note that the upscattering mechanism could be distinguished from decays in future observations if sources with different dark matter velocity dispersions seem to require different values of the scattering cross section to match the observed line strengths.

  12. In situ observation of microstructure evolution in tungsten under 400 keV Kr+ irradiation

    NASA Astrophysics Data System (ADS)

    Ran, Guang; Huang, Shilin; Huang, Zijing; Yan, Qingzhi; Xu, Jiangkun; Li, Ning; Wang, Lumin

    2014-12-01

    Tungsten was irradiated with 400 keV Kr+ ions using the IVEM-Tandem Facility at Argonne National Laboratory. The evolution of microstructure and gas bubbles during the irradiation was observed by in situ transmission electron microscopy. Under irradiation, dislocation loops were created and grew into an increased density of network dislocations with increasing Kr+ ion fluence. The irradiation induced final microstructure consists of dislocation cells ?50 nm in diameter separated by dislocation walls. The irradiation also induced formation of Kr gas bubbles with an average diameter of 1.4 nm after 3.0 × 1016 ions/cm2 at 525 K. The gas bubbles were observed to grow to 2.6 nm diameter after additional Kr-irradiation of 5.0 × 1016 ions/cm2 at 815 K. The relationship between bubble size and irradiation time was obtained from experimental data obtained at 815 K and an empirical formula for calculating Kr bubble size was developed by fitting bubble growth equations with experiment data. The growth mechanisms of Kr gas bubbles in tungsten are discussed.

  13. Optimizing 9-25 keV point projection 2D backlighters

    NASA Astrophysics Data System (ADS)

    Baker, Kevin; MacLaren, Steve; Glendinning, Gail; Seugling, Richard; Whiting, Nick; Source, Chuck; Fooks, Julie; Fournier, Kevin; Biener, Monika; Martinez, David; Smalyuk, Vladimir; Dittrich, Tom; Moore, Alastair; Guymer, Tom

    2013-10-01

    The conversion efficiency of zinc He? backlighter and silver k? sources have been studied on the OMEGA laser. A common platform was used to evaluate the conversion efficiency from Zn foils with and without a 2.8 ns prepulse and from low density zinc foams containing varying quantities of zinc relative to low Z foam constituents. The common platform consisted of a 2 mm diameter by 2 mm long tube that was either filled with a low density foam or had two foils glued on the ends of an empty tube. The foam targets, which underwent volume ionization, exhibited more uniform radial emission above 1 keV than the foil targets. The thinnest Zn exploding foil targets stagnated in the middle of the tube producing a temporally longer He? emission than the other targets. The highest overall conversion efficiency came from a foil target driven with a 2.8 ns prepulse. Initial results from silver k? sources will also be presented.

  14. Teflon impregnated anatase TiO2 nanoparticles irradiated by 80 keV Xe+ ions

    NASA Astrophysics Data System (ADS)

    Khanam, Rizwin; Paul, Nibedita; Kumar, P.; Kanjilal, D.; Ahmed, Gazi A.; Mohanta, Dambarudhar

    2014-10-01

    We report the effect of 80 keV Xe+ ion irradiation on the morphological and optical responses of TiO2 nanoparticles spread over commercially available polytetrafluoroethylene (PTFE, Teflon). These nanoparticles were synthesized via a convenient, sol-gel approach with titanium isopropoxide as the main precursor. From X-ray diffraction (XRD) studies we found that, the nanoparticles crystallize in anatase phase and with a preferential orientation of crystallites along (1 0 1) plane. Upon irradiation at a fluence of 1.25 × 1017 ions/cm2, the nanoparticle dimension was found to increase from a value of ˜9 nm to ˜20-30 nm. Essentially, particle growth is predicted as a consequence of swelling behavior accompanied by the formation of Xe van der Waal crystals in isolated regions of nano-titania. Evidence of nanoripples was also witnessed on the surface of the irradiated nano-titania. The morphological evolution was assessed both by atomic force and transmission electron microscopies (AFM and TEM) independently. From the UV-Vis optical absorption studies, the estimated optical band gap was found to drop with increasing fluence, while refractive index exhibited a remarkable improvement. Photoluminescence (PL) studies have revealed that, the band edge emission and those due to the self trapped excitons (STE) and other oxygen vacancy related ones were manifested considerably as a result of Xe ion irradiation.

  15. Present Status of 200 KEV Polarized Electron Gun at Nagoya University

    NASA Astrophysics Data System (ADS)

    Yamamoto, M.; Yamamoto, N.; Nakanishi, T.; Okumi, S.; Furuta, F.; Miyamoto, M.; Kuwahara, M.; Naniwa, K.; Yasui, K.; Kuriki, M.; Matsumoto, H.; Yoshioka, M.

    2005-08-01

    A proto-type of 200 keV electron gun for a future linear collider has been constructed at Nagoya University. The degradation of a negative electron affinity (NEA) surface of a GaAs photocathode is known as a major problem for such a high field gradient gun, since the gun is required to produce the high intensity and low emittance beam. In order to improve the NEA lifetime (~40 h) for the initial gun operation, the vacuum pumping speed was reinforced by using non-evaporable getter (NEG) modules. As a preliminary result, the total pressure was improved to 5.7 × 10-10 Pa and the lifetime was extended to ~150 hours. A relation between the NEA lifetime and the partial pressures of CO2 and H2O was evaluated by assuming a simple model for a mechanizm of NEA degradation. An emittance measurement system based on a pepper pot method was also build and a preliminary measurement has been started.

  16. Measuring the 511 keV emission in the direction of 1E1740.7-2942 with BATSE

    NASA Technical Reports Server (NTRS)

    Wallyn, P.; Ling, J. C.; Mahoney, W. A.; Wheaton, W. A.; Durouchoux, P.; Corbel, S.; Astier-Perret, L.; Poirot, L.

    1997-01-01

    Observations of the 511 keV emission in the direction of 1E 1740.7-2942 (1E) using the earth burst and transient source experiment (BATSE) onboard the Compton Gamma Ray Observatory (CGRO), are presented. The CGRO phase 1 average spectrum of 1E is calculated using a method which assumes that a given source spectrum is the sum of the flux coming directly from the object and the contribution from the surrounding diffuse emission. The 1E light curve is calculated in the 40 to 150 keV range. It presents a constant flux excess of 70 mCrab in comparison with observations from the SIGMA gamma ray telescope onboard the GRANAT observatory. By removing this contribution, the 1E spectral transition from the low state to the high standard state observed by SIGMA is confirmed, and it is shown that the 511 keV flux is independent of the 1E long term evolution from low state to high standard state. It is concluded that the 511 keV emission of (4.2 +/- 1.3) x 140(exp -4) photons/sq cm s observed in the direction of 1E is mainly diffuse and spatially extended.

  17. Tracking down the Source Population Responsible for the Unresolved Cosmic 6-8 keV Background

    NASA Astrophysics Data System (ADS)

    Xue, Y. Q.; Wang, S. X.; Brandt, W. N.; Luo, B.; Alexander, D. M.; Bauer, F. E.; Comastri, A.; Fabian, A. C.; Gilli, R.; Lehmer, B. D.; Schneider, D. P.; Vignali, C.; Young, M.

    2012-10-01

    Using the 4 Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray-undetected galaxies that dominates the unresolved ?20%-25% of the 6-8 keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South Hubble Space Telescope z-band imaging of the central 6'radius area of the 4 Ms CDF-S. The stacked 6-8 keV detection is significant at the 3.9? level, but the stacked emission was not detected in the 4-6 keV band, which indicates the existence of an underlying population of highly obscured active galactic nuclei (AGNs). Further examinations of these 6845 galaxies indicate that the galaxies on the top of the blue cloud and with redshifts of 1 <~ z <~ 3, magnitudes of 25 <~ z 850 <~ 28, and stellar masses of 2 × 108 <~ M sstarf/M ? <~ 2 × 109 make the majority contributions to the unresolved 6-8 keV XRB. Such a population is seemingly surprising given that the majority of the X-ray-detected AGNs reside in massive (gsim 1010 M ?) galaxies. We discuss constraints upon this underlying AGN population, supporting evidence for relatively low mass galaxies hosting highly obscured AGNs, and prospects for further boosting the stacked signal.

  18. OSSE observations of Galactic 511 keV positron annihilation radiation - Initial phase 1 results. [Oriented Scintillation Spectrometer Experiment

    NASA Technical Reports Server (NTRS)

    Purcell, W. R.; Grabelsky, D. A.; Ulmer, M. P.; Johnson, W. N.; Kinzer, R. L.; Kurfess, J. D.; Strickman, M. S.; Jung, G. V.

    1993-01-01

    The Oriented Scintillation Spectrometer Experiment (OSSE) on the Compton Gamma-Ray Observatory (GRO) has performed numerous observations of the Galactic plane and Galactic center region to measure the distribution of Galactic 511 keV positron annihilation radiation and to search for time variability of the emission. The initial 511 keV line fluxes for the observations performed during the first 18 months of the GRO mission are presented. The 511 keV line flux for a typical Galactic center observation is (2.5 +/- 0.3) x 10 exp -4 gamma/sq cm per sec, where the quoted uncertainty represents the 1 sigma statistical uncertainty. No statistically significant time variability of the line flux has been observed; the 3 sigma upper limit to daily variations from the mean is 3 x 10 exp -4 gamma/sq cm per sec. The distribution of Galactic 511 keV positron annihilation radiation implied by the OSSE observations is discussed and compared with observations by other instruments.

  19. Molecular dynamics simulation of radiation damage in CaCd6 quasicrystal cubic approximant up to 10 keV

    E-print Network

    Nordlund, Kai

    Molecular dynamics simulation of radiation damage in CaCd6 quasicrystal cubic approximant up to 10 keV P. H. Chen, K. Avchachov, K. Nordlund, and K. Pussi Citation: J. Chem. Phys. 138, 234505 (2013); doi: 10.1063/1.4811183 View online: http://dx.doi.org/10.1063/1.4811183 View Table of Contents: http

  20. ANL/APS/LS-313 Short-Period APPLE II Undulator for Generating 12-15 keV

    E-print Network

    Kemner, Ken

    ANL/APS/LS-313 Short-Period APPLE II Undulator for Generating 12-15 keV X-Rays at the Advanced APPLE II design. In this note, we present magnet design calculations and radiation calculations are not important for the first harmonic and for the issues discussed in this note). Magnet Modeling of APPLE II

  1. Avalanche Diode Low Energy X-Ray and Nuclear Particle Detector

    Microsoft Academic Search

    M. R. Squillante; R. Farrell; J. C. Lund; F. Sinclair; G. Entine; K. R. Keller

    1986-01-01

    Avalanche diodes which are sensitive enough to detect low energy x-rays and beta particles have been fabricated and tested. They operate at room temperature and their structure is based on large area avalanche photodiodes. X-ray response has been measured over the energy range of 4 keV to 26 keV. At 5.9 keV a FWHM of 10% was obtained. In addition,

  2. High-brightness, high-spatial-resolution, 6.151 keV x-ray imaging of inertial confinement fusion capsule implosion and complex hydrodynamics experiments on Sandia's Z accelerator (invited)

    SciTech Connect

    Bennett, G. R.; Sinars, D. B.; Wenger, D. F.; Cuneo, M. E.; Adams, R. G.; Barnard, W. J.; Beutler, D. E.; Burr, R. A.; Campbell, D. V.; Claus, L. D.; Foresi, J. S.; Johnson, D. W.; Keller, K. L.; Lackey, C.; Leifeste, G. T.; McPherson, L. A.; Mulville, T. D.; Neely, K. A.; Rambo, P. K.; Rovang, D. C. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185-1106 (United States)] (and others)

    2006-10-15

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' 20 MA, 100 ns rise-time Z accelerator [M. K. Matzen et al., Phys. Plasmas 12, 055503 (2005)], the terawatt-class, multikilojoule, 526.57 nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151 keV, Mn-He{sub {alpha}} curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004)], is capable of providing a high quality x radiograph per Z shot for various high-energy-density physics experiments. Enhancements to this imaging system during 2005 have led to the capture of inertial confinement fusion capsule implosion and complex hydrodynamics images of significantly higher quality. The three main improvements, all leading effectively to enhanced image plane brightness, were bringing the source inside the Rowland circle to approximately double the collection solid angle, replacing direct exposure film with Fuji BAS-TR2025 image plate (read with a Fuji BAS-5000 scanner), and generating a 0.3-0.6 ns, {approx}200 J prepulse 2 ns before the 1.0 ns, {approx}1 kJ main pulse to more than double the 6.151 keV flux produced compared with a single 1 kJ pulse. It appears that the 20{+-}5 {mu}m imaging resolution is limited by the 25 {mu}m scanning resolution of the BAS-5000 unit, and to this end, a higher resolution scanner will replace it. ZBL is presently undergoing modifications to provide two temporally separated images ('two-frame') per Z shot for this system before the accelerator closes down in summer 2006 for the Z-refurbished (ZR) upgrade. In 2008, after ZR, it is anticipated that the high-energy petawatt (HEPW) addition to ZBL will be completed, possibly allowing high-energy 11.2224 and 15.7751 keV K{alpha}{sub 1} curved-crystal imaging to be performed. With an ongoing several-year project to develop a highly sensitive multiframe ultrafast digital x-ray camera (MUDXC), it is expected that two-frame HEPW 11 and 16 keV imaging and four-frame ZBL 6.151 keV curved-crystal imaging will be possible. MUDXC will be based on the technology of highly cooled silicon and germanium photodiode arrays and ultrafast, radiation-hardened integrated circuitry.

  3. 2-20 ns interframe time 2-frame 6.151 keV x-ray imaging on the recently upgraded Z Accelerator: A progress report

    SciTech Connect

    Bennett, G. R.; Smith, I. C.; Shores, J. E.; Sinars, D. B.; Robertson, G.; Atherton, B. W.; Jones, M. C.; Porter, J. L. [Sandia National Laboratories, P.O. Box 5800, Albuquerque, New Mexico 87185-1193 (United States)

    2008-10-15

    When used for the production of an x-ray imaging backlighter source on Sandia National Laboratories' recently upgraded 26 MA Z Accelerator, the terawatt-class, multikilojoule, 526.57 nm Z-Beamlet laser (ZBL) [P. K. Rambo et al., Appl. Opt. 44, 2421 (2005)], in conjunction with the 6.151 keV (1s{sup 2}-1s2p triplet line of He-like Mn) curved-crystal imager [D. B. Sinars et al., Rev. Sci. Instrum. 75, 3672 (2004); G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)], is capable of providing a high quality x radiograph per Z shot for inertial confinement fusion (ICF), complex hydrodynamics, and other high-energy-density physics experiments. For example, this diagnostic has recently afforded microgram-scale mass perturbation measurements on an imploding ignition-scale 1 mg ICF capsule [G. R. Bennett et al., Phys. Rev. Lett. 99, 205003 (2007)], where the perturbation was initiated by a surrogate deuterium-tritium (DT) fuel fill tube. Using an angle-time multiplexing technique, ZBL now has the capability to provide two spatially and temporally separated foci in the Z chamber, allowing 'two-frame' imaging to be performed, with an interframe time range of 2-20 ns. This multiplexing technique allows the full area of the four-pass amplifiers to be used for the two pulses, rather than split the amplifiers effectively into two rectangular sections, with one leg delayed with respect to the other, which would otherwise double the power imposed onto the various optics thereby halving the damage threshold, for the same irradiance on target. The 6.151 keV two frame technique has recently been used to image imploding wire arrays, using a 7.3 ns interframe time. The diagnostic will soon be converted to operate with p-rather than s-polarized laser light for enhanced laser absorption in the Mn foil, plus other changes (e.g., operation at the possibly brighter 6.181 keV Mn 1s{sup 2}-1s2p singlet line), to increase x-ray yields. Also, a highly sensitive inline multiframe ultrafast (1 ns gate time) digital x-ray camera is being developed [G. R. Bennett et al., Rev. Sci. Instrum. 77, 10E322 (2006)] to extend the system to 'four-frame' and markedly improve the signal-to-noise ratio. [At present, time-integrating Fuji BAS-TR2025 image plate (scanned with a Fuji BAS-5000 device) forms the time-integrated image-plane detector.].

  4. Destabilization of olivine by 30-keV electron irradiation: a possible mechanism of space weathering affecting interplanetary dust particles and planetary surfaces

    NASA Astrophysics Data System (ADS)

    Lemelle, L.; Beaunier, L.; Borensztajn, S.; Fialin, M.; Guyot, F.

    2003-05-01

    Electron irradiation experiments were performed using a 30-keV electron beam on single crystals of olivine in a scanning electron microscope (SEM) and in an electron microprobe (EMP). We determined that, under certain conditions, structural damage is caused to the irradiated surface of iron-bearing olivines. The irradiated areas comprise spherules with sizes of hundreds of nanometers and micrometer-sized holes. In the immediate vicinities of the irradiated areas, droplets with sizes of tens of nanometers and branching tracks are observed. With increasing total charge, the hundreds of nanometer-sized spherules become larger and more irregular in shape. The size and shape of the nanometer-sized droplets remain almost constant, but their surface density increases (in m -2). Chemical fractionations compared to the initial olivine were found: the irradiated areas are slightly enriched in MgO, whereas the deposits are enriched in SiO 2. Destabilization of olivine is not due to the dissipation of the implanted energy as heat, but results most probably from electrostatic discharges leading to the breakdown of the dielectric lattice. The possibility that such processes could be responsible for significant space weathering of interplanetary dust particles and regoliths of planetary surfaces should be taken into account. In the interplanetary medium, 10-keV range electrons are carried by the solar wind, whereas at 1 AU from the Sun, the lifetime of cometary dust and the exposure time of lunar regolith are, at least, 10 to 100 times greater than the duration required to accumulate the damaging electronic doses applied in this study. Moreover, the comparison of the microstructures of samples irradiated in the present study with features of lunar regolith grains reveals several chemical and structural similarities.

  5. A Search for a keV Signature of Radiatively Decaying Dark Matter with Suzaku XIS Observations of the X-ray Diffuse Background

    E-print Network

    Norio Sekiya; Noriko Y. Yamasaki; Kazuhisa Mitsuda

    2015-07-15

    We performed the deepest search for an X-ray emission line between 0.5 and 7 keV from non-baryonic dark matter with the Suzaku XIS. Dark matter associated with the Milky Way galaxy was selected as the target to obtain the best signal-to-noise ratio. From the Suzaku archive, we selected 187 data sets of blank sky regions which were dominated by the X-ray diffuse background. The data sets were from 2005 to 2013. Instrumental responses were adjusted by multiple calibration data sets of the Crab Nebula. We also improved the technique of subtracting lines of instrumental origin. These energy spectra were well described by X-ray emission due to charge exchange around the Solar System, hot plasma in and around the Milky Way and superposition of extra-galactic point sources. A signal of a narrow emission line was searched for, and the significance of detection was evaluated in consideration of the blind search method (the Look-elsewhere Effect). Our results exhibited no significant detection of an emission line feature from dark matter. The 3$\\sigma$ upper limit for the emission line intensity between 1 and 7 keV was $\\sim10^{-2}$ photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$, or $\\sim 5\\times10^{-4}$ photons cm$^{-2}$ s$^{-1}$ sr$^{-1}$ per $M_\\odot$ pc$^{-2}$, assuming a dark matter distribution with the Galactic rotation curve. The parameters of sterile neutrinos as candidates of dark matter were also constrained.

  6. New generation of efficient high resolution detector for 30-100 keV

    E-print Network

    ) Risø National Laboratory for Sustainable Energy Technical University of Denmark Roskilde, Denmark for Sustainable Energy Technical University of is submitted in partial fulfillment of the requirements for the Ph.D. degree at Copenhagen University Abstract

  7. Structural and optical properties of 70-keV carbon ion beam synthesized carbon nanoclusters in thermally grown silicon dioxide

    NASA Astrophysics Data System (ADS)

    Poudel, P. R.; Poudel, P. P.; Paramo, J. A.; Strzhemechny, Y. M.; Rout, B.; McDaniel, F. D.

    2015-02-01

    The structural and optical properties of carbon nanoclusters formed in thermally grown silicon dioxide film via the ion beam synthesis process have been investigated. A low-energy (70 keV) carbon ion beam (C-) at a fluence of 3 × 1017 atoms/cm2 was used for implantation into a thermally grown silicon dioxide layer (500 nm thick) on a Si (100) wafer. Several parts of the implanted samples were subsequently annealed in a gas mixture (4 % H2 + 96 % Ar) at 900 °C for different time periods. The as-implanted and annealed samples were characterized by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy, Raman spectroscopy, transmission electron microscopy (TEM), and photoluminescence spectroscopy (PL). The carbon ion implantation depth profile was simulated using a widely used Monte Carlo-based simulation code SRIM-2012. Additionally, the elemental depth profile of the implanted carbon along with host elements of silicon and oxygen were simulated using a dynamic ion-solid interaction code T-DYN, which incorporates the effects of the surface sputtering and gradual change in the elemental composition in the implanted layers due to high-fluence ion implantation. The elemental depth profile obtained from the XPS measurements matches closely to the T-DYN predictions. Raman measurements indicate the formation of graphitic phases in the annealed samples. The graphitic peak (G-peak) was found to be increased with the annealing time duration. In the sample annealed for 10 min, the sizes of the carbon nanoclusters were found to be 1-4 nm in diameter using TEM. The PL measurements at room temperature using a 325-nm laser show broad-band emissions in the ultraviolet to visible range in the as-implanted sample. Intense narrow bands along with the broad bands were observed in the annealed samples. The defects present in the as-grown samples along with carbon ion-induced defect centers in the as-implanted samples are the main contributors to the observed broad-band luminescence centered around 2.4 and 2.9 eV. The intense narrow peaks observed in the PL spectra centered on ~2.67 and 2.8 eV with full width at half maxima ? 150 meV are believed to be mainly due to the quantum size effects of the carbon nanoclusters formed in the annealed samples. The relative intensities of the narrow peaks are seen to be changing with the annealing time interval. This may be due to the change in the size distribution of the carbon nanoclusters.

  8. Cross sections of K-shell ionization by electron impact, measured from threshold to 100 keV, for Au and Bi

    NASA Astrophysics Data System (ADS)

    Fernández-Varea, J. M.; Jahnke, V.; Maidana, N. L.; Malafronte, A. A.; Vanin, V. R.

    2014-08-01

    We have measured cross sections for the ionization of the K shell by electrons with energies from the respective thresholds up to 100 keV, for Au and Bi. The experimental values are obtained by dividing the number of counts in the K? peak by the number of counts in an energy interval near the tip of the bremsstrahlung continuum, and multiplying this ratio by the theoretical estimate of bremsstrahlung emission towards the detector in this energy interval. Although such a procedure has already been described in the literature, here it is implemented avoiding some of the simplifications made in earlier works. Our experimental cross sections, which are the first ones to be reported for atoms with Z>47 close to the threshold, are in reasonable agreement with the theoretical predictions of the semirelativistic distorted-wave Born approximation. Hippler's plane-wave Born approximation with corrections for Coulomb and exchange effects yields cross sections that are closer to the experimental data than those evaluated from the relativistic binary-encounter-Bethe model.

  9. A CHANDRA OBSERVATION OF 3C 288—REHEATING THE COOL CORE OF A 3 keV CLUSTER FROM A NUCLEAR OUTBURST at z = 0.246

    E-print Network

    Lal, D. V.

    We present results from a 42 ks Chandra/ACIS-S observation of the transitional FR I/FR II radio galaxy 3C 288 at z = 0.246. We detect ~3 keV gas extending to a radius of ~0.5 Mpc with a 0.5-2.0 keV luminosity of 6.6 × ...

  10. Experiments with low-energy muons

    Microsoft Academic Search

    F. J. Hartmann; H. Daniel; Chr Maierl; M. Mühlbauer; W. Schott; P. Wojciechowski; P. Hauser; C. Petitjean; D. Taqqu; F. Kottmann; V. E. Markushin

    1996-01-01

    Two experiments with low-energy muons are described: the determination of the stopping power of C, Si, Ti and Au for muons at energies down to 2 keV and the measurement of the diffusion times for pµ and dµ atoms in low-pressure (0.25–12 hPa) hydrogen gas. A pronounced Barkas effect was found for muons at the Bragg peak (about 10 keV):

  11. Monte Carlo Simulations of Defect Recovery within a 10 keV Collision Cascade in 3C-SiC

    SciTech Connect

    Rong, Zhouwen; Gao, Fei; Weber, William J.

    2007-11-26

    A kinetic lattice Monte Carlo (KLMC) model is developed to investigate the recovery and clustering of defects during annealing of a single 10 keV cascade in cubic silicon carbide. The 10 keV Si cascade is produced by molecular dynamics (MD), and a method of transferring the defects created by MD simulations to the KLMC model is developed. The KLMC model parameters are obtained from molecular dynamics simulations and ab initio calculations of defect migration, recombination and annihilation. The defects are annealed isothermally from 100 K to 1000 K in the KLMC model. Two distinct recovery stages for close Frenkel pairs are observed at about 200 and 550 K, and the growth of complex clusters is observed above 400 K. These simulation results are in good agreement with available experimental results.

  12. Diagnostics for the optimization of an 11 keV inverse Compton scattering x-ray source

    SciTech Connect

    Chauchat, A.-S.; Brasile, J.-P [Thales Communications and Security, 4 avenue des Louvresses 92230 Gennevilliers (France); Le Flanchec, V.; Negre, J.-P.; Binet, A. [CEA DAM DIF, Bruyeres-le-Chatel 91290 Arpajon (France); Ortega, J.-M. [LCP Universite Paris-Sud, Bat. 201, 91405 Orsay (France)

    2013-04-19

    In a scope of a collaboration between Thales Communications and Security and CEA DAM DIF, 11 keV Xrays were produced by inverse Compton scattering on the ELSA facility. In this type of experiment, X-ray observation lies in the use of accurate electron and laser beam interaction diagnostics and on fitted X-ray detectors. The low interaction probability between < 100 {mu}m width, 12 ps [rms] length electron and photon pulses requires careful optimization of pulse spatial and temporal covering. Another issue was to observe 11 keV X-rays in the ambient radioactive noise of the linear accelerator. For that, we use a very sensitive detection scheme based on radio luminescent screens.

  13. THM determination of the 65 keV resonance strength intervening in the 17O ( p ,?)14N reaction rate

    NASA Astrophysics Data System (ADS)

    Sergi, M. L.; Spitaleri, C.; Burjan, S. V.; Cherubini, S.; Coc, A.; Gulino, M.; Hammache, F.; Hons, Z.; Irgaziev, B.; Kiss, G. G.; Kroha, V.; La Cognata, M.; Lamia, L.; Mukhamedzhanov, A.; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; de Séréville, N.; Somorjai, E.; Tumino, A.

    2015-02-01

    The 17O ( p ,?)14N reaction is of paramount importance for the nucleosynthesis in a number of stellar sites, including red giants (RG), asymptotic giant branch (AGB) stars, massive stars and classical novae. We report on the indirect study of the 17O ( p ,?)14N reaction via the Trojan Horse Method by applying the approach recently developed for extracting the resonance strength of the narrow resonance at Ec.m.R = 65 keV (EX =5.673 MeV). The strength of the 65 keV resonance in the 17O ( p ,?)14N reaction, measured by means of the THM, has been used to renormalize the corresponding resonance strength in the 17O + p radiative capture channel.

  14. A galactic component of the diffuse X-ray flux in the range 2-7 keV

    NASA Technical Reports Server (NTRS)

    Protheroe, R. J.; Wolfendale, A. W.; Wdowczyk, J.

    1980-01-01

    An analysis of the spatial distribution of the 2-7 keV X-ray background measured by Uhuru and reported by Schwartz (1979) is presented. The latitude distribution above 10 deg is consistent with a uniform isotropic component comprising the bulk of the radiation plus a galactic part varying from 3% at /b/ = 20 deg to 1% at /b/ = 90 deg. An analysis was made of the residual background based on the work of Warwick, Pye, and Fabian, in terms of a directional anisotropy as indicated by the Compton-Getting effect; the symmetrical galactic contribution was subtracted in the computations. It was shown that the results are consistent with the solar system moving through the 2-7 keV X-ray sea in the same manner as it appears to move with respect to the 2.7 K radiation.

  15. Sterile neutrino dark matter in B-L extension of the standard model and galactic 511 keV line

    SciTech Connect

    Khalil, Shaaban [Centre for Theoretical Physics, The British University in Egypt, El Sherouk City, Postal No. 11837, PO Box 43 (Egypt)] [Centre for Theoretical Physics, The British University in Egypt, El Sherouk City, Postal No. 11837, PO Box 43 (Egypt); Seto, Osamu, E-mail: skhalil@bue.edu.eg, E-mail: seto@physics.umn.edu [Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, Cantoblanco, Madrid 28049 (Spain)] [Instituto de Fisica Teorica UAM/CSIC, Universidad Autonoma de Madrid, Cantoblanco, Madrid 28049 (Spain)

    2008-10-15

    Sterile right-handed neutrinos can be naturally embedded in a low scale gauged U(1){sub B-L} extension of the standard model. We show that, within a low reheating scenario, such a neutrino is an interesting dark matter candidate. We emphasize that if the neutrino mass is of the order of MeV, then it accounts for the measured dark matter relic density and also accommodates the observed flux of 511 keV photons from the galactic bulge.

  16. Simulation of keV particle bombardment of covalent materials: An investigation of the yield dependence on incidence angle

    Microsoft Academic Search

    Roger Smith; Don E. Harrison; Barbara J. Garrison

    1990-01-01

    The dependence of the yield, Y, of ejected particles on the angle of incidence theta is investigated for the keV particle bombardment of Si by molecular dynamics simulations using many-body potentials to describe the atom\\/atom interactions and a Molière potential to describe the ion\\/atom interactions. Results are presented for the Si{110} and the dimer reconstructed Si{100}(2 × 1) surfaces. For

  17. Nuclear Bragg diffraction of synchrotron radiation at the 8.41 keV resonance of thulium

    Microsoft Academic Search

    W. Sturhahn; E. Gerdau; R. Hollatz; R. Rüffer; H. D. Rüter; W. Tolksdorf

    1991-01-01

    For the first time nuclear Bragg diffraction of synchrotron radiation at the 8.41 keV resonance of 169Tm was observed. Time differential measurements were performed with the pure nuclear (424) reflection of a thulium iron garnet single crystal. The dynamical theory of Mössbauer optics is applied to evaluate the time spectra. The measurements reveal information about the hyperfine fields which has

  18. Multi-processor control of the 100 KeV McMaster mark IV sputter ion source

    Microsoft Academic Search

    W. F. S. Poehlman; R. A. McNaught; R. J. Pollock

    1985-01-01

    An ion source control system has been developed to provide 100 KeV heavy ion injection into the McMaster FN Tandem. The control system is composed of a CMOS RCA1802 microprocessor at deck potential which conveys power supply command\\/status data from\\/to a PDP-11\\/23 via fibre optic link. Approximately 50 fail safe interlock conditions are maintained by the PDP with capabilities to

  19. Elastic scattering of 22.1keV photons by elements in the atomic region 12<=Z<=92

    Microsoft Academic Search

    J. S. Shahi; Sanjiv Puri; D. Mehta; M. L. Garg; Nirmal Singh; P. N. Trehan

    1997-01-01

    Differential cross sections for the elastic scattering of 22.1-keV photons by 30 elements in the atomic region 12<=Z<=92 have been measured at an angle of 117°. The measurements were performed under vacuum using Si(Li) detector and 109Cd radioisotope as photon source. The intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K x-ray yields

  20. Constraints on 3.55 keV line emission from stacked observations of dwarf spheroidal galaxies

    E-print Network

    D. Malyshev; A. Neronov; D. Eckert

    2014-08-15

    Several recent works have reported the detection of an unidentified X-ray line at 3.55 keV, which could possibly be attributed to the decay of dark matter (DM) particles in the halos of galaxy clusters and in the M31 galaxy. We analyze all publicly-available XMM-Newton data of dwarf spheroidal galaxies to test the possible DM origin of the line. Dwarf spheroidal galaxies have high mass-to-light ratios and their interstellar medium is not a source of diffuse X-ray emission, thus they are expected to provide the cleanest DM decay line signal. Our analysis shows no evidence for the presence of the line in the stacked spectra of the dwarf galaxies. It excludes the sterile neutrino DM decay origin of the 3.5 keV line reported by Bulbul et al. (2014) at the level of 4.6 sigma under standard assumptions about the Galactic DM column density in the direction of selected dwarf galaxies and at the level of 3.3 sigma assuming minimal Galactic DM column density. As a by-product of our analysis, we provide updated upper limits to the mixing angle of sterile neutrino DM in the mass range between 2 and 20 keV.

  1. Differential cross sections for scattering of 0.5-, 1.5-, and 5.0-keV hydrogen atoms by He, H2, N2, and O2

    NASA Technical Reports Server (NTRS)

    Newman, J. H.; Chen, Y. S.; Smith, K. A.; Stebbings, R. F.

    1986-01-01

    This paper reports measurements of absolute cross sections, differential in angle, for scattering of 0.5-, 1.5-, and 5.0-keV hydrogen atoms by He, H2, N2, and O2 at laboratory scattering angles between 0.1 and 5 deg. The measured cross sections are the sums of those for elastic and inelastic collisions having a fast H atom product and are needed for calculating energy transfer to the upper atmosphere from precipitating ring current particles.

  2. The Effect of an External Magnetic Field on L X-ray Intensity Ratios for Elements in the Range 73? Z? 92 at 59.54 keV

    NASA Astrophysics Data System (ADS)

    Demir, Demet; ?ahin, Yusuf

    2007-11-01

    The L shell x-ray intensity ratios L?/Ll, L?/L?, and L?/L? for Ta, W, Au, Hg, Tl, Pb, Bi, Th, and U have been measured using the 59.54 keV incident photon energy in the external magnetic field of intensities ± 0.15, ± 0.45, and ± 0.75 T. A comparison is made of the experimental values obtained for B=0 with calculated values using theoretical x-ray emission rates, subshell ionization cross sections, subshell fluorescence yields and Coster-Kronig transitions probabilities. In the absence of external magnetic field, a fairly agreement is observed between experimental and theoretical values.

  3. Measurement of the L/K electron capture ratio of the 207Bi decay to the 1633 keV level of 207Pb with a BGO scintillating bolometer

    NASA Astrophysics Data System (ADS)

    Coron, N.; Cuesta, C.; García, E.; Ginestra, C.; Gironnet, J.; de Marcillac, P.; Martínez, M.; Ortigoza, Y.; Pobes, C.; Puimedón, J.; Redon, T.; Salinas, A.; Sarsa, M. L.; Torres, L.; Watrin, A.

    2012-06-01

    The ROSEBUD Collaboration has dedicated several underground runs to study different types of bolometers, mainly for the search of dark matter. Some of these runs, profiting from the good energy resolution of one bolometer of BGO and the ultra-low background of the underground laboratory of Canfranc (LSC), allowed the measurement of the L/ K electron capture ratio of the 207Bi decay to the 1633 keV level of 207Pb. This paper constitutes the first published measurement of this magnitude.

  4. Measurements of the K-shell ionization cross sections of Si by 3-25-keV electron impact using the thick-target method

    SciTech Connect

    Zhu Jingjun; An Zhu; Liu Mantian; Tian Lixia [Key Laboratory of Radiation Physics and Technology of Ministry of Education, Institute of Nuclear Science and Technology, Sichuan University, Chengdu 610064 (China)

    2009-05-15

    In this paper, the K-shell ionization cross sections of Si element in the threshold energy region of 3-25 keV have been measured by using the thick-target method. With the Monte Carlo simulations, the effects of multiple scattering of incident electrons and from the bremsstrahlung photons and other secondary particles in the thick-target method have been discussed. The detection efficiency calibration in the lower-energy region has been performed by using the bremsstrahlung spectra of thick carbon target by electron impact in combination with the use of standard x-ray sources, and the detector thickness parameters have also been determined by a nonlinear least-squares fit. The ill-posed inverse problem involved in the thick-target method has been dealt with by the Tikhonov regularization method. The experimental K-shell ionization cross sections for Si element obtained in this paper have also been compared with some theoretical models, and it has been observed that the experimental data in this paper are in good agreement with the theoretical values based on the distorted-wave Born approximation model developed most recently.

  5. High-Energy\\/Low-Energy Proportional Counter (HEPC\\/LEPC) detector systems on the SRG

    Microsoft Academic Search

    Carl C. Budtz-Joergensen; Axel Bahnsen; M. M. Madsen; C. Olesen; P. Jonasson; Herbert W. Schnopper

    1994-01-01

    The low energy proportional counter LEPC (0.2 - 8 keV) and the high energy proportional counter HEPC (2 - 25 keV) for the Danish-Russian X-ray telescopes XSPECT\\/SODART are presently being tested at DSRI. The sensor principle of these detectors is based on the novel micro strip gas counter (MSGC) where the strip electrodes are deposited by photolithography onto a rigid

  6. X-Ray Detector for 1 to 30 keV

    NASA Technical Reports Server (NTRS)

    Alcorn, G.; Jackson, J., Jr; Grant, P.; Marshall, F.

    1983-01-01

    Array of silicon X-ray detecting diodes measures photon energy and provides image of X-ray pattern. Regardless of thickness of new X-ray detector, depletion region extends through it. Impinging X-rays generate electrons in quantities proportional to X-ray energy. X-ray detector is mated to chargecoupled-device array for image generation and processing. Useful in industrial part inspection, pulsed-plasma research and medical application.

  7. New elastic electron scattering factors for the elements for incident energies of 10, 40, 60, and 90 keV

    SciTech Connect

    Ross, A.W.; Fink, M.

    1986-12-01

    An improved set of scattering factors for all neutral elements has bee completed for inclusion in the new edition of the International Tables of X-ray Crystallography . These calculations are compared with the former electron scattering factors and the deviations between the two are discussed.(AIP)

  8. Absolute Doubly Differential Cross Sections for Ejection of Electrons in - and Five-Body Collisions of 20 TO 114-KEV Protons on Atomic and Molecular Hydrogen.

    NASA Astrophysics Data System (ADS)

    Kerby, George W., III

    A crossed-beam experiment was performed to detect ejected electrons from ground-state atomic and molecular hydrogen after collisions with 20- to 114-keV protons. Because a pure atomic hydrogen target is not readily attainable, a method has been devised which yields atomic to molecular hydrogen doubly differential cross section (DDCS) ratios. Since the molecular hydrogen DDCS's were independently measured, the atomic cross sections could be directly calculated. Absolute cross sections differential in electron energy and angle were measured for electron energies ranging from 1.5 to 400 eV and scattering angles from 15^circ to 165^circ with respect to the fast beam. Electrons and ions were energy analyzed by an electrostatic hemispherical analyzer, which has an energy resolution of 5% and is rotatable in the scattering plane about the collision center. Atomic hydrogen is produced by a radio-frequency discharge of the type devised by J. Slevin. Hydrogen gas effuses from a 1 mm diameter nozzle in a nearly cos theta distribution. The projectile beam intersects the thermal gas targets 4 mm below the tip of the nozzle. Dissociation fractions of 74% and atomic hydrogen densities of 7 times 10 ^{11} cm^ {-3} were typical. The fraction of dissociated hydrogen was measured by detecting the reduced 9-eV ion signal from the molecular target when the RF is on. This characteristic ion signal originates from the coulomb breakup of the molecule and dissociative channels of excited H _sp{2}{+}. An auxiliary experiment was performed to determine the target densities with the aid of a low-resolution magnetic mass spectrometer after the slow recoil ions were extracted from the collision volume by a weak electric field. Comparisons of the atomic cross sections are made with theories such as the classical-trajectory Monte Carlo (CTMC) method, the plane-wave Born approximation (PWBA) and the continuum-distorted-wave eikonal-initial-state (CDW-EIS) approximation.

  9. State-selective nonresonant transfer excitation in 50--400-keV sup 3 He sup + +H sub 2 and He collisions

    SciTech Connect

    Jain, A. (Department of Physics, Florida A M University, Box 981, Tallahassee, Florida 32307 (US)); Shingal, R. (Department of Physics, Kansas State University, Manhattan, Kansas 66506 (USA)); Zouros, T.J.M. (Department of Physics, University of Crete, Iraklion and Foundation for Research an Technology-Hellas (FORTH), Iraklion (Greece))

    1991-02-01

    Cross sections for nonresonant transfer excitation (NTE) are calculated for collisions of {sup 3}He{sup +} with H{sub 2} (2H) and He targets in the 50--500-keV impact-energy range. Single-electron capture probabilities to the 2{ital s} and 2{ital p} orbitals of He and single-electron excitation probabilities for He{sup +} (1{ital s}{r arrow}2{ital s} or 2{ital p}) transitions are independently computed, as a function of impact parameter, using the semiclassical multichannel-impact-parameter model with an expansion in atomic orbitals placed either on one or both centers. NTE cross sections for the (2{ital s}{sup 2}){sup 1}{ital S}, (2{ital p}{sup 2}){sup 1}{ital D}, and (2{ital s}2{ital p}){sup 1}{ital P} states, computed in the independent-electron model, are compared with the recent high-resolution electron data for transfer excitation into these states. For He{sup +}+H{sub 2} collisions, NTE is found to contribute primarily at the low collision energies, dropping off at the higher energies. On the contrary, for the symmetric He{sup +}+He collisions, NTE cross sections do not drop off with impact energy as expected. In the case of the (2{ital p}{sup 2}){sup 1}{ital D} state, an increase in the cross section, similar to the experimental data, is seen. However, in both cases, the calculated cross section seems to be larger than the experimental data.

  10. New Observations of the Solar 0.5-5 keV Soft X-Ray Spectrum

    NASA Astrophysics Data System (ADS)

    Caspi, Amir; Woods, Thomas N.; Warren, Harry P.

    2015-03-01

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ˜0.2 and ˜4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially integrated solar spectral irradiance from ˜0.5 to ˜5 keV, with ˜0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5-10 MK) emission and are well fit by simple power-law temperature distributions with indices of ˜6, close to the predictions of nanoflare models of coronal heating. Observations during the more active 2013 flight indicate an enrichment of low first-ionization potential elements of only ˜1.6, below the usually observed value of ˜4, suggesting that abundance variations may be related to coronal heating processes. The XUV Photometer System Level 4 data product, a spectral irradiance model derived from integrated broadband measurements, significantly overestimates the spectra from both flights, suggesting a need for revision of its non-flare reference spectra, with important implications for studies of Earth ionospheric dynamics driven by solar SXRs.

  11. Stability of Extraterrestrial Glycine under Energetic Particle Radiation Estimated from 2 keV Electron Bombardment Experiments

    NASA Astrophysics Data System (ADS)

    Maté, B.; Tanarro, I.; Escribano, R.; Moreno, M. A.; Herrero, V. J.

    2015-06-01

    The destruction of solid glycine under irradiation with 2 keV electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO2, CO, OCN?, and CN? and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of ?150 nm is found to provide efficient shielding against the bombardment of 2 keV electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely.

  12. Surface morphology and structural changes in insulators induced by high-current 60 keV Cu implantation

    Microsoft Academic Search

    C. G. Lee; Y. Takeda; N. Kishimoto; N. Umeda

    2001-01-01

    Surface morphology and structural changes of amorphous (a-), crystalline (c-) SiO2 and MgAl2O4 spinel, implanted with high-current Cu- of 60 keV, were studied using atomic force microscopy. Kinetic variation of the surface morphology was evaluated by changing dose rate from 1 to 100 muA\\/cm2. In the cases of a-SiO2 and c-SiO2, the surface morphology significantly varied with dose rate: dome-type

  13. Enhanced keV peak power and yield using twisted pair ``cables'' in a z-pinch

    NASA Astrophysics Data System (ADS)

    Hoyt, C. L.; Knapp, P. F.; Pikuz, S. A.; Shelkovenko, T. A.; Cahill, A. D.; Gourdain, P.-A.; Greenly, J. B.; Kusse, B. R.; Hammer, D. A.

    2012-06-01

    Individual wires in a z-pinch were replaced with twisted pair "cables" of similar linear mass on the COBRA pulsed power generator, resulting in peak power and yield increases in radiation above 1 keV. A cable is defined here as two or more fine wires twisted together to form a continuous strand with a wavelength (?t) dependent on the twists per unit length. The magnitude of ?t appears to play a strong role in these increases, with the largest gains found for a ?t of ?0.75 mm.

  14. Photoelectric cross sections of Al, Cu, Zr, Ag, Sn, Ta and Pb for 145 keV ?rays

    Microsoft Academic Search

    R Gowda; B Sanjeevaiah

    1973-01-01

    Measurements of photoelectric cross sections of aluminium, copper, zirconium, silver, tin, tantalum and lead for 145 keV gamma rays have been carried out using the well-type plastic scintillation spectrometer. The cross sections in these materials are found to be 0.261+or-0.018, 10.32+or-0.62, 37.82+or-2.27, 79.83+or-4.80, 98.97+or-5.90, 430.9+or-25.00 and 671.0+or-40.00 b\\/atom respectively. These values are found to be in good agreement with the

  15. Nonthermal Two Component Dark Matter Model for Fermi-LAT $?$-ray excess and 3.55 keV X-ray Line

    E-print Network

    Anirban Biswas; Debasish Majumdar; Probir Roy

    2015-03-23

    A two component model of nonthermal dark matter is formulated to simultaneously explain the Fermi-LAT results indicating a $\\gamma$-ray excess observed from our Galactic Centre in the 1-3 GeV energy range and the detection of an X-ray line at 3.55 keV from extragalactic sources. Two additional Standard Model singlet scalar fields $S_2$ and $S_3$ are introduced. These fields couple among themselves and with the Standard Model Higgs doublet $H$. The interaction terms among the scalar fields, namely $H$, $S_2$ and $S_3$, are constrained by the application of a discrete $\\mathbb{Z}_2\\times \\mathbb{Z}^\\prime_2$ symmetry which breaks softly to a remnant $\\mathbb{Z}^{\\prime \\prime}_2$ symmetry. This residual discrete symmetry is then spontaneously broken through an MeV order vacuum expectation value $u$ of the singlet scalar field $S_3$. The resultant physical scalar spectrum has the Standard Model like Higgs as $\\chi_{{}_{{}_1}}$ with $M_{\\chi_{{}_{{}_1}}}\\sim 125$ GeV, a moderately heavy scalar $\\chi_{{}_{{}_2}}$ with $50 \\,\\,{\\rm GeV} \\leq M_{\\chi_{{}_{{}_2}}}\\leq 80\\,\\,{\\rm GeV}$ and a light $\\chi_{{}_{{}_3}}$ with $M_{\\chi_{{}_{{}_3}}} \\sim 7$ keV. There is only tiny mixing between $\\chi_{{}_{{}_1}}$ and $\\chi_{{}_{{}_2}}$ as well as between $\\chi_{{}_{{}_1}}$ and $\\chi_{{}_{{}_3}}$. The lack of importance of domain wall formation in the present scenario from the spontaneous breaking of the discrete symmetry ${\\mathbb{Z}_2^{\\prime\\prime}}$, provided $u\\leq 10$ MeV, is pointed out. We find that our proposed two component dark matter model is able to explain successfully both the above mentioned phenomena $-$ the Fermi-LAT observed $\\gamma$-ray excess (from the $\\chi_{{}_{{}_2}} \\rightarrow {\\rm b} \\bar{\\rm b}$ decay mode) and the observation of the X-ray line (from the decay channel $\\chi_{{}_{{}_3}}\\rightarrow\\gamma \\gamma$) by the XMM-Newton observatory.

  16. A new study of the $^{22}$Ne(p,$?$)$^{23}$Na reaction deep underground: Feasibility, setup, and first observation of the 186 keV resonance

    E-print Network

    F. Cavanna; R. Depalo; M. -L. Menzel; M. Aliotta; M. Anders; D. Bemmerer; C. Broggini; C. G. Bruno; A. Caciolli; P. Corvisiero; T. Davinson; A. di Leva; Z. Elekes; F. Ferraro; A. Formicola; Zs. Fülöp; G. Gervino; A. Guglielmetti; C. Gustavino; Gy. Gyürky; G. Imbriani; M. Junker; R. Menegazzo; P. Prati; C. Rossi Alvarez; D. A. Scott; E. Somorjai; O. Straniero; F. Strieder; T. Szücs; D. Trezzi

    2014-11-25

    The $^{22}$Ne(p,$\\gamma$)$^{23}$Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the $^{22}$Ne(p,$\\gamma$)$^{23}$Na cross section directly at the astrophysically relevant energies are needed. In the present work, a feasibility study for a $^{22}$Ne(p,$\\gamma$)$^{23}$Na experiment at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400\\,kV accelerator deep underground in the Gran Sasso laboratory, Italy, is reported. The ion beam induced $\\gamma$-ray background has been studied. The feasibility study led to the first observation of the $E_{\\rm p}$ = 186\\,keV resonance in a direct experiment. An experimental lower limit of 0.12\\,$\\times$\\,10$^{-6}$\\,eV has been obtained for the resonance strength. Informed by the feasibility study, a dedicated experimental setup for the $^{22}$Ne(p,$\\gamma$)$^{23}$Na experiment has been developed. The new setup has been characterized by a study of the temperature and pressure profiles. The beam heating effect that reduces the effective neon gas density due to the heating by the incident proton beam has been studied using the resonance scan technique, and the size of this effect has been determined for a neon gas target.

  17. International Fusion Materials Irradiation Facility injector acceptance tests at CEA/Saclay: 140 mA/100 keV deuteron beam characterization

    NASA Astrophysics Data System (ADS)

    Gobin, R.; Bogard, D.; Cara, P.; Chauvin, N.; Chel, S.; Delferrière, O.; Harrault, F.; Mattei, P.; Mosnier, A.; Senée, F.; Shidara, H.; Okumura, Y.

    2014-02-01

    In the framework of the ITER broader approach, the International Fusion Materials Irradiation Facility (IFMIF) deuteron accelerator (2 × 125 mA at 40 MeV) is an irradiation tool dedicated to high neutron flux production for future nuclear plant material studies. During the validation phase, the Linear IFMIF Prototype Accelerator (LIPAc) machine will be tested on the Rokkasho site in Japan. This demonstrator aims to produce 125 mA/9 MeV deuteron beam. Involved in the LIPAc project for several years, specialists from CEA/Saclay designed the injector based on a SILHI type ECR source operating at 2.45 GHz and a 2 solenoid low energy beam line to produce such high intensity beam. The whole injector, equipped with its dedicated diagnostics, has been then installed and tested on the Saclay site. Before shipment from Europe to Japan, acceptance tests have been performed in November 2012 with 100 keV deuteron beam and intensity as high as 140 mA in continuous and pulsed mode. In this paper, the emittance measurements done for different duty cycles and different beam intensities will be presented as well as beam species fraction analysis. Then the reinstallation in Japan and commissioning plan on site will be reported.

  18. A new study of the 22Ne(p, ?)23Na reaction deep underground: Feasibility, setup and first observation of the 186 keV resonance

    NASA Astrophysics Data System (ADS)

    Cavanna, F.; Depalo, R.; Menzel, M.-L.; Aliotta, M.; Anders, M.; Bemmerer, D.; Broggini, C.; Bruno, C. G.; Caciolli, A.; Corvisiero, P.; Davinson, T.; di Leva, A.; Elekes, Z.; Ferraro, F.; Formicola, A.; Fülöp, Zs.; Gervino, G.; Guglielmetti, A.; Gustavino, C.; Gyürky, Gy.; Imbriani, G.; Junker, M.; Menegazzo, R.; Prati, P.; Rossi Alvarez, C.; Scott, D. A.; Somorjai, E.; Straniero, O.; Strieder, F.; Szücs, T.; Trezzi, D.

    2014-11-01

    The 22Ne(p, ?)23Na reaction takes part in the neon-sodium cycle of hydrogen burning. This cycle is active in asymptotic giant branch stars as well as in novae and contributes to the nucleosythesis of neon and sodium isotopes. In order to reduce the uncertainties in the predicted nucleosynthesis yields, new experimental efforts to measure the 22Ne(p, ?)23Na cross section directly at the astrophysically relevant energies are needed. In the present work, a feasibility study for a 22Ne(p, ?)23Na experiment at the Laboratory for Underground Nuclear Astrophysics (LUNA) 400 kV accelerator deep underground in the Gran Sasso laboratory, Italy, is reported. The ion-beam-induced ?-ray background has been studied. The feasibility study led to the first observation of the E p=186 keV resonance in a direct experiment. An experimental lower limit of 0.12 × 10-6 eV has been obtained for the resonance strength. Informed by the feasibility study, a dedicated experimental setup for the 22Ne(p, ?)23Na experiment has been developed. The new setup has been characterized by a study of the temperature and pressure profiles. The beam heating effect that reduces the effective neon gas density due to the heating by the incident proton beam has been studied using the resonance scan technique, and the size of this effect has been determined for a neon gas target.

  19. International Fusion Materials Irradiation Facility injector acceptance tests at CEA/Saclay: 140 mA/100 keV deuteron beam characterization

    SciTech Connect

    Gobin, R., E-mail: rjgobin@cea.fr; Bogard, D.; Chauvin, N.; Chel, S.; Delferrière, O.; Harrault, F.; Mattei, P.; Senée, F. [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/Saclay, DSM/IRFU, 91191-Gif/Yvette (France)] [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/Saclay, DSM/IRFU, 91191-Gif/Yvette (France); Cara, P. [Fusion for Energy, BFD Department, Garching (Germany)] [Fusion for Energy, BFD Department, Garching (Germany); Mosnier, A. [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/Saclay, DSM/IRFU, 91191-Gif/Yvette (France) [Commissariat à l’Energie Atomique et aux Energies Alternatives, CEA/Saclay, DSM/IRFU, 91191-Gif/Yvette (France); Fusion for Energy, BFD Department, Garching (Germany); Shidara, H. [IFMIF/EVEDA Project Team, Obuchi-Omotedate 2-166, Rokkasho, Aomori (Japan)] [IFMIF/EVEDA Project Team, Obuchi-Omotedate 2-166, Rokkasho, Aomori (Japan); Okumura, Y. [JAEA, Division of Rokkasho BA Project, Obuchi-Omotedate 2-166, Rokkasho, Aomori (Japan)] [JAEA, Division of Rokkasho BA Project, Obuchi-Omotedate 2-166, Rokkasho, Aomori (Japan)

    2014-02-15

    In the framework of the ITER broader approach, the International Fusion Materials Irradiation Facility (IFMIF) deuteron accelerator (2 × 125 mA at 40 MeV) is an irradiation tool dedicated to high neutron flux production for future nuclear plant material studies. During the validation phase, the Linear IFMIF Prototype Accelerator (LIPAc) machine will be tested on the Rokkasho site in Japan. This demonstrator aims to produce 125 mA/9 MeV deuteron beam. Involved in the LIPAc project for several years, specialists from CEA/Saclay designed the injector based on a SILHI type ECR source operating at 2.45 GHz and a 2 solenoid low energy beam line to produce such high intensity beam. The whole injector, equipped with its dedicated diagnostics, has been then installed and tested on the Saclay site. Before shipment from Europe to Japan, acceptance tests have been performed in November 2012 with 100 keV deuteron beam and intensity as high as 140 mA in continuous and pulsed mode. In this paper, the emittance measurements done for different duty cycles and different beam intensities will be presented as well as beam species fraction analysis. Then the reinstallation in Japan and commissioning plan on site will be reported.

  20. Dwarf Galaxy $\\gamma$-excess and 3.55 keV X-ray Line In A Nonthermal Dark Matter Model

    E-print Network

    Biswas, Anirban; Roy, Probir

    2015-01-01

    Recent data on the dwarf spheroidal galaxy, Reticulum II (RetII) have increased the energy range of the Fermi-LAT $\\gamma$-excess from $1-3$ GeV to $2-10$ GeV with a peak around 7 GeV. In order to fit this new range, a modification is required of our earlier unified nonthermal scalar Dark Matter (DM) model, proposed with two extra scalars beyond the Standard Model, to explain both the Fermi-LAT $\\gamma$-excess from the Galactic Centre and the XMM Newton Observatory 3.55 keV X-ray line. The mass of one of our extra scalars has to be increased from $50-80$ GeV to $250-300$ GeV $-$ changing both the seed mechanism for the $\\gamma$-excess and the Boltzmann equation for the generation of the DM relic density. We show, however, that with this increased scalar mass all concerned data for RetII and the X-ray line can be well-fitted.

  1. The Z accelerator as a source of > 100 kJ of x-rays above 4.8 keV

    SciTech Connect

    Deeney, C.; Coverdale, C.A.; Spielman, R.B. [and others

    1998-04-13

    Recent K-shell scaling experiments on the 20 MA Z accelerator at Sandia National Laboratories have shown that large diameter (40 and 55 mm) arrays can be imploded with 80 to 210 wires of titanium or stainless steel. These implosions have produced up to 150 kJ of > 4.5 keV x-rays and 65 kJ of > 6.0 keV x-rays in 7 to 18 ns FWHM pulses. This is a major advance in plasma radiation source (PRS) capability since there is presently limited test capability above 3 keV. In fact, Z produces more > 4.5 keV x-rays than previous aboveground simulators produced at 1.5 keV. Z also produces some 200 kJ of x-rays between 1 and 3 keV in a continuous spectrum for these loads. The measured spectra and yields are consistent with 1-dimensional MHD calculations performed by NRL. Thermoelastic calorimeters, PVDF gauges, and optical impulse gauges have been successfully fielded with these sources.

  2. Comparison of photon attenuation coefficients (2-150 KeV) for diagnostic imaging simulations

    NASA Astrophysics Data System (ADS)

    Dodge, Charles W., III; Flynn, Michael J.

    2004-05-01

    The Radiology Research Laboratory at the Henry Ford Hospital has been involved in modeling x-ray units in order to predict image quality. A critical part of that modeling process is the accurate choice of interaction coefficients. This paper serves as a review and comparison of existing interaction models. Our objective was to obtain accurate and easily calculated interaction coefficients, at diagnostically relevant energies. We obtained data from: McMaster, Lawrence Berkeley Lab data (LBL), XCOM and FFAST Data from NIST, and the EPDL-97 database via LLNL. Our studies involve low energy photons; therefore, comparisons were limited to Coherent (Rayleigh), Incoherent (Compton) and Photoelectric effects, which were summed to determine a total interaction cross section. Without measured data, it becomes difficult to definitively choose the most accurate method. However, known limitations in the McMaster data and smoothing of photo-edge transitions can be used as a guide to establish more valid approaches. Each method was compared to one another graphically and at individual points. We found that agreement between all methods was excellent when away from photo-edges. Near photo-edges and at low energies, most methods were less accurate. Only the Chanter (FFAST) data seems to have consistently and accurately predicted the placement of edges (through M-shell), while minimizing smoothing errors. The EPDL-97 data by LLNL was the best over method in predicting coherent and incoherent cross sections.

  3. A New Understanding of Near-Threshold Damage for 200 keV Irradiation In Silicon

    SciTech Connect

    Stoddard, Nathan [North Carolina State University; Duscher, Gerd J M [ORNL; Windl, Wolfgang [Ohio State University; Rozgonyi, G. A. [North Carolina State University

    2005-01-01

    Recently we reported room temperature point defect creation and subsequent extended defect nucleation in nitrogen-doped silicon during 200 kV electron irradiation, while identical irradiation of nitrogen-free silicon produced no effect. In this paper, first principles calculations are combined with new transmission electron microscope (TEM) observations to support a new model for elastic electron-silicon interactions in the TEM, which encompasses both nitrogen doped and nitrogen free silicon. Specifically, the nudged elastic band method was used to study the energetics along the diffusion path during an electron collision event in the vicinity of a nitrogen pair. It was found that the 0 K estimate for the energy barrier of a knock-on event is lowered from {approx}12 to 6.2 eV. However, this is still inadequate to explain the observations. We therefore propose an increase in the energy barrier for Frenkel pair recombination associated with N{sub 2}-V bonding. Concerning pure silicon, stacking fault formation near irradiation-induced holes demonstrates the participation of bulk processes. In low oxygen float zone material, 2--5 nm voids were formed, while oxygen precipitation in Czochralski Si has been verified by electron energy-loss spectroscopy. Models of irradiation-induced point defect aggregation are presented and it is concluded that these must be bulk and not surface mediated phenomena.

  4. Relic Gravity Waves and 7 keV Dark Matter from a GeV scale inflaton

    E-print Network

    F. Bezrukov; D. Gorbunov

    2015-01-29

    We study the mechanism of generation of 7 keV sterile neutrino Dark Matter (DM) in the model with light inflaton $\\chi$, which serves as a messenger of scale invariance breaking. In this model the inflaton, in addition to providing reheating to the Standard Model (SM) particles, decays directly into sterile neutrinos. The latter are responsible for the active neutrino oscillations via seesaw type I like formula. While the two sterile neutrinos may also produce the lepton asymmetry in the primordial plasma and hence explain the baryon asymmetry of the Universe, the third one being the lightest may be of 7 keV and serve as DM. For this mechanism to work, the mass of the inflaton is bound to be light (0.1-1 GeV) and uniquely determines its properties, which allows to test the model. For particle physics experiments these are: inflaton lifetime ($10^{-5}-10^{-12}$ s), partial decay width of B-meson to kaon and inflaton ($10^{-6}-10^{-4}$) and inflaton branching ratios into light SM particles like it would be for the SM Higgs boson of the same mass. For cosmological experiments these are: spectral index of scalar perturbations ($n_s\\simeq0.957-0.967$), and amount of tensor perturbations produced at inflation (tensor-to-scalar ratio $r\\simeq0.15-0.005$).

  5. Monte-Carlo-derived insights into dose–kerma–collision kerma inter-relationships for 50?keV–25?MeV photon beams in water, aluminum and copper

    NASA Astrophysics Data System (ADS)

    Kumar, Sudhir; Deshpande, Deepak D.; Nahum, Alan E.

    2015-01-01

    The relationships between D, K and Kcol are of fundamental importance in radiation dosimetry. These relationships are critically influenced by secondary electron transport, which makes Monte-Carlo (MC) simulation indispensable; we have used MC codes DOSRZnrc and FLURZnrc. Computations of the ratios D/K and D/Kcol in three materials (water, aluminum and copper) for large field sizes with energies from 50?keV to 25?MeV (including 6–15?MV) are presented. Beyond the depth of maximum dose D/K is almost always less than or equal to unity and D/Kcol greater than unity, and these ratios are virtually constant with increasing depth. The difference between K and Kcol increases with energy and with the atomic number of the irradiated materials. D/K in ‘sub-equilibrium’ small megavoltage photon fields decreases rapidly with decreasing field size. A simple analytical expression for \\overline{X} , the distance ‘upstream’ from a given voxel to the mean origin of the secondary electrons depositing their energy in this voxel, is proposed: {{\\overline{X}}\\text{emp}}? 0.5{{R}\\text{csda}}(\\overline{{{E}0}}) , where \\overline{{{E}0}} is the mean initial secondary electron energy. These {{\\overline{X}}\\text{emp}} agree well with ‘exact’ MC-derived values for photon energies from 5–25?MeV for water and aluminum. An analytical expression for D/K is also presented and evaluated for 50?keV–25?MeV photons in the three materials, showing close agreement with the MC-derived values.

  6. Monte-Carlo-derived insights into dose-kerma-collision kerma inter-relationships for 50?keV-25?MeV photon beams in water, aluminum and copper.

    PubMed

    Kumar, Sudhir; Deshpande, Deepak D; Nahum, Alan E

    2015-01-21

    The relationships between D, K and Kcol are of fundamental importance in radiation dosimetry. These relationships are critically influenced by secondary electron transport, which makes Monte-Carlo (MC) simulation indispensable; we have used MC codes DOSRZnrc and FLURZnrc. Computations of the ratios D/K and D/Kcol in three materials (water, aluminum and copper) for large field sizes with energies from 50?keV to 25?MeV (including 6-15?MV) are presented. Beyond the depth of maximum dose D/K is almost always less than or equal to unity and D/Kcol greater than unity, and these ratios are virtually constant with increasing depth. The difference between K and Kcol increases with energy and with the atomic number of the irradiated materials. D/K in 'sub-equilibrium' small megavoltage photon fields decreases rapidly with decreasing field size. A simple analytical expression for X?, the distance 'upstream' from a given voxel to the mean origin of the secondary electrons depositing their energy in this voxel, is proposed: X?(emp) ? 0.5R(csda)(E?(0)), where E?(0) is the mean initial secondary electron energy. These X?(emp) agree well with 'exact' MC-derived values for photon energies from 5-25?MeV for water and aluminum. An analytical expression for D/K is also presented and evaluated for 50?keV-25?MeV photons in the three materials, showing close agreement with the MC-derived values. PMID:25548933

  7. KeV Ion Beam Induced Surface Modification of SiC Hydrogen Sensor

    SciTech Connect

    Muntele, C.I.; Ila, D.; Williams, E.K.; Poker, D.B.; Hensley, D.K.

    1999-11-29

    Silicon carbide, a wide-bandgap semiconductor, is currently used to fabricate an efficient high temperature hydrogen sensor. When a palladium coating is applied on the exposed surface of silicon carbide, the chemical reaction between palladium and hydrogen produces a detectable change in the surface chemical potential. Rather than applying a palladium film, we have implanted palladium ions into the silicon face of 6H, n-type Sic samples. The implantation energies and fluences, as well as the results obtained by monitoring the current through the sample in the presence of hydrogen are included in this paper.

  8. The average number of neutrons ? eff emitted by the isotopes U 233 , U 235 and Pu 239 on capture of neutrons with energies from 30 to 900 key

    Microsoft Academic Search

    P. E. Spivak; B. G. Erozolimsky; G. A. Dorofeev; V. N. Lavrenchik; I. E. Kutikov; Yu. P. Dobrynin

    1956-01-01

    Measurements are taken on ?eff for the isotopes U233, U235 and Pu239 for neutrons with energies from 30 to 900 kev. It is discovered that in this energy region ?eff increases substantially as the neutron energy increases.

  9. Energy.

    ERIC Educational Resources Information Center

    Online-Offline, 1998

    1998-01-01

    This issue focuses on the theme of "Energy," and describes several educational resources (Web sites, CD-ROMs and software, videos, books, activities, and other resources). Sidebars offer features on alternative energy, animal energy, internal combustion engines, and energy from food. Subthemes include harnessing energy, human energy, and natural…

  10. Bragg diffraction using a 100ps 17.5 keV x-ray backlighter and the Bragg Diffraction Imager

    SciTech Connect

    Maddox, B R; Park, H; Hawreliak, J; Comley, A; Elsholz, A; Van Maren, R; Remington, B A; Wark, J

    2010-05-13

    A new diagnostic for measuring Bragg diffraction from a laser-driven crystal using a 100ps 17.5 kV x-ray backlighter source is designed and tested successfully at the Omega EP laser facility on static Mo and Ta single crystal samples using a Mo Ka backlighter. The Bragg Diffraction Imager (BDI) consists of a heavily shielded enclosure and a precisely positioned beam block, attached to the main enclosure by an Aluminum arm. Image plate is used as the x-ray detector. The diffraction lines from Mo and Ta <222> planes are clearly detected with a high signal-to-noise using the 17.5 keV and 19.6 keV characteristic lines generated by a petawatt-driven Mo foil. This technique will be applied to shock and ramp-loaded single crystals on the Omega EP laser. Pulsed x-ray diffraction of shock- and ramp-compressed materials is an exciting new technique that can give insight into the dynamic behavior of materials at ultra-high pressure not achievable by any other means to date. X-ray diffraction can be used to determine not only the phase and compression of the lattice at high pressure, but by probing the lattice compression on a timescale equal to the 3D relaxation time of the material, information about dislocation mechanics, including dislocation multiplication rate and velocity, can also be derived. Both Bragg, or reflection, and Laue, or transmission, diffraction have been developed for shock-loaded low-Z crystalline structures such as Cu, Fe, and Si using nano-second scale low-energy implosion and He-{alpha} x-ray backlighters. However, higher-Z materials require higher x-ray probe energies to penetrate the samples, such as in Laue, or probe deep enough into the target, as in the case of Bragg diffraction. Petawatt laser-generated K{alpha} x-ray backlighters have been developed for use in high-energy radiography of dense targets and other HED applications requiring picosecond-scale burst of hard x-rays. While short pulse lasers are very efficient at producing high-energy x-rays, the characteristic x-rays produced in these thin foil targets are superimposed on a broad bremsstrahlung background and can easily saturate a detector if careful diagnostic shielding and experimental geometry are not implemented. A new diagnostic has been designed to measure Bragg diffraction from laser-driven crystal targets using characteristic x-rays from a short-pulse laser backlighter on the Omega EP laser. The Bragg Diffraction Imager, or BDI, is a TIM-mounted instrument consisting of a heavily shielded enclosure made from 3/8-inch thick Heavymet (W-Fe-Ni alloy) and a precisely positioned beam bock, attached to the main enclosure by an Aluminum arm. The beam block is made of 1-inch thick, Al-coated Heavymet and serves to block the x-rays directly from the petawatt backlight, while allowing the diffraction x-rays from the crystal to pass to the enclosure. A schematic of the BDI is shown in Fig. 1a. Image plates are used as the x-ray detector and are loaded through the top of the diagnostic in an Aluminum, light-tight cartridge. The front of the enclosure can be fitted with various filters to maximize the diffraction signal-to-noise.

  11. Investigation of pulsed X-ray radiation of a plasma focus in a broad energy range

    SciTech Connect

    Savelov, A. S., E-mail: vniia@vniia.ru; Salakhutdinov, G. Kh. [National Research Nuclear Center 'MIFI,' (Russian Federation); Koltunov, M. V.; Lemeshko, B. D.; Yurkov, D. I.; Sidorov, P. P. [Federal State Unitary Enterprise 'VNII Avtomatiki,' (Russian Federation)

    2011-12-15

    The results of the experimental investigations of the spectral composition of plasma focus X-ray radiation in the photon energy range of 1.5 keV-400 keV are presented. Three regions in the radiation spectrum where the latter is of a quasi-thermal nature with a corresponding effective temperature are distinguished.

  12. Search for 14.4 keV solar axions from M1 transition of {sup 57}Fe with CUORE crystals

    SciTech Connect

    NONE

    2013-05-01

    We report the results of a search for axions from the 14.4 keV M1 transition from {sup 57}Fe in the core of the sun using the axio-electric effect in TeO{sub 2} bolometers. The detectors are 5 × 5 × 5 cm{sup 3} crystals operated at about 10 mK in a facility used to test bolometers for the CUORE experiment at the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 43.65 kg?d of data was made using a newly developed low energy trigger which was optimized to reduce the energy threshold of the detector. An upper limit of 0.58 c?kg{sup ?1}?d{sup ?1} is established at 95% C.L., which translates into lower bounds f{sub A} ? 3.12 × 10{sup 5} GeV 95% C.L. (DFSZ model) and f{sub A} ? 2.41 × 10{sup 4} GeV 95% C.L. (KSVZ model) on the Peccei-Quinn symmetry-breaking scale, for a value of S = 0.5 of the flavor-singlet axial vector matrix element. These bounds can be expressed in terms of axion masses as m{sub A} ? 19.2 eV and m{sub A} ? 250 eV at 95% C.L. in the DFSZ and KSVZ models respectively. Bounds are given also for the interval 0.35 ? S ? 0.55.

  13. Gamma-ray burst spectra and time histories from 2 to 400 keV

    SciTech Connect

    Fenimore, E.E.

    1998-07-01

    The Gamma-Ray burst detector on Ginga consisted of a proportional counter to observe the x-rays and a scintillation counter to observe the gamma-rays. Both instrument recorded the time histories in phase with each other and with 0.03125 s temporal resolution. The author compares the average of 21 gamma-ray bursts to determine the delay, in any, between the peak of the x-rays and the peak of the gamma-rays. The delay is less than or about equal to 30 msec. Thus, models must content with two average features of the temporal behavior. First, as a function of energy, the time structure scales as {approximately}E{sup {minus}0.45}. Second, the x-rays are not appreciable delayed relative to the gamma-rays. Some cooling models might have difficulties explaining these features.

  14. Simulation of low energy muon frictional cooling

    Microsoft Academic Search

    R. Galea; A. Caldwell; S. Schlenstedt; H. Abramowicz

    2006-01-01

    Frictional cooling is a proposed method of phase space reduction for a potential muon beam intended for collisions. The basic principle involves compensating for the muon energy loss in media by a constant electric field. The muons are in an energy regime below the ionization peak which for muons in helium is less than 10keV. Electronic energy loss is treated

  15. Energy!

    NSDL National Science Digital Library

    Mr. Larsen

    2009-09-24

    Students will be introduced to energy, what it is and the different forms of energy. Energy - the ability to do work! Energy is necessary to our everyday lives and is found all around us all the time. We can not do anything without using energy. For the purposes of this class it is important that we understand there are ...

  16. Sub-Angstrom transmission electron microscopy at 300keV

    SciTech Connect

    O'Keefe, Michael A.; Nelson, E. Christian; Turner, John H.; Thust, Andreas

    2001-02-14

    We have demonstrated sub-Angstrom TEM to a resolution of 0.78 Angstrom with the one-Angstrom microscope (OAM) project at the National Center for Electron Microscopy. The OAM combines a modified CM300FEG-UT with computer software able to generate sub-Angstrom images from experimental image series. We achieved sub-Angstrom resolution with the OAM by paying close attention to detail. We placed the TEM in a favorable environment. We reduced its three-fold astigmatism A2 from 2.46mm to 300 Angstrom (corresponding to transfer of 0.68 Angstrom spacings at a pi/4 phase limit). We improved its information limit by minimizing high-voltage and lens current ripple. Energy spread of 0.93eV FWHH gave a focus spread of 20 Angstrom and an information limit of 0.78 Angstrom, allowing successful resolution of the 0.89 Angstrom (400) atom spacings in [110] diamond. As a further test, we reduced the electron gun extraction voltage to 3kV to improve our information limit to 0.75 Angstrom, and then imaged 0 .7 Angstrom (444) atom spacings in [112] silicon as distinct pairs of 'white atoms' near an alpha-null defocus of -3783 Angstrom.

  17. The electrical properties of 60 keV zinc ions implanted into semi-insulating gallium arsenide

    NASA Technical Reports Server (NTRS)

    Littlejohn, M. A.; Anikara, R.

    1972-01-01

    The electrical behavior of zinc ions implanted into chromium-doped semiinsulating gallium arsenide was investigated by measurements of the sheet resistivity and Hall effect. Room temperature implantations were performed using fluence values from 10 to the 12th to 10 to the 15th power/sq cm at 60 keV. The samples were annealed for 30 minutes in a nitrogen atmosphere up to 800 C in steps of 200 C and the effect of this annealing on the Hall effect and sheet resistivity was studied at room temperature using the Van der Pauw technique. The temperature dependence of sheet resistivity and mobility was measured from liquid nitrogen temperature to room temperature. Finally, a measurement of the implanted profile was obtained using a layer removal technique combined with the Hall effect and sheet resistivity measurements.

  18. Enhanced room temperature oxidation in silicon and porous silicon under 10 keV x-ray irradiation

    SciTech Connect

    Ryckman, Judson D.; Reed, Robert A.; Weller, Robert A.; Fleetwood, D. M.; Weiss, S. M. [Department of Electrical Engineering and Computer Science, Vanderbilt University, Nashville, Tennessee 37235 (United States)

    2010-12-01

    We report the observation of enhanced oxidation on silicon and porous silicon samples exposed in air ambient to high-dose-rate 10 keV x-ray radiation at room temperature. The evolution of the radiation-induced oxide growth is monitored by ellipsometry and interferometric reflectance spectroscopy. Fourier transform infrared (FTIR) spectroscopy shows the emergence of Si-O-Si stretching modes and corresponding suppression of SiH{sub x} and Si-Si modes in the porous silicon samples. The radiation response depends strongly on initial native oxide thickness and Si-H surface species. The enhanced oxidation mechanism is attributed to photoinduced oxidation processes wherein energetic photons are used to dissociate molecular oxygen and promote the formation of more reactive oxygen species.

  19. Differential cross sections for single ionization of H{sub 2} by 75-keV proton impact

    SciTech Connect

    Chowdhury, U.; Schulz, M.; Madison, D. H. [Missouri University of Science and Technology, Department of Physics and Laboratory for Atomic, Molecular, and Optical Research, Rolla, Missouri 65401 (United States)

    2011-03-15

    We have calculated triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H{sub 2} by 75-keV proton impact using the molecular three-body distorted-wave-eikonal initial-state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles that were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H{sub 2} as atomic H multiplied by a molecular interference factor only predicts the observed structure when assumptions are made about the molecular orientation. Here we apply the M3DW-EIS method, which does not rely on such an ad hoc approach, but rather treats the interference from first principles.

  20. Improvement of voltage holding capability in the 500 keV negative ion source for JT-60SAa)

    NASA Astrophysics Data System (ADS)

    Tanaka, Y.; Hanada, M.; Kojima, A.; Akino, N.; Shimizu, T.; Ohshima, K.; Inoue, T.; Watanabe, K.; Taniguchi, M.; Kashiwagi, M.; Umeda, N.; Tobari, H.; Grisham, L. R.; JT-60 Nbi Group

    2010-02-01

    Voltage holding capability of JT-60 negative ion source that has a large electrostatic negative ion accelerator with 45 cm×1.1 m acceleration grids was experimentally examined and improved to realize 500 keV, 22 A, and 100 s D- ion beams for JT-60 Super Advanced. The gap lengths in the acceleration stages were extended to reduce electric fields in a gap between the large grids and at the corner of the support flanges from the original 4-5 to 3-4 kV/mm. As a result, the voltage holding capability without beam acceleration has been successfully improved from 400 to 500 kV. The pulse duration to hold 500 kV reached 40 s of the power supply limitation.