Science.gov

Sample records for 10-600 kev energy

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

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 10.600 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts,...

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

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 10.600 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts,...

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

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 10.600 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts,...

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

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 10.600 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY ARTICLES CONDITIONALLY FREE, SUBJECT TO A REDUCED RATE, ETC. Dominican Republic-Central America-United States Free Trade Agreement Rules of Origin § 10.600 Accessories, spare parts,...

  5. 19 CFR 10.600 - Accessories, spare parts, or tools.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Accessories, spare parts, or tools. 10.600 Section... tools. (a) General. Accessories, spare parts, or tools that are delivered with a good and that form part of the good's standard accessories, spare parts, or tools will be treated as originating goods if...

  6. High resolution 17 keV to 75 keV backlighters for High Energy Density experiments

    SciTech Connect

    Park, H; Maddox, B R; Giraldez, E; Hatchett, S P; Hudson, L; Izumi, N; Key, M H; Pape, S L; MacKinnon, A J; MacPhee, A G; Patel, P K; Phillips, T W; Remington, B A; Seely, J F; Tommasini, R; Town, R; Workman, J

    2008-02-25

    We have developed 17 keV to 75 keV 1-dimensional and 2-dimensional high-resolution (< 10 {micro}m) radiography using high-intensity short pulse lasers. High energy K-{alpha} sources are created by fluorescence from hot electrons interacting in the target material after irradiation by lasers with intensity I{sub L} > 10{sup 17} W/cm{sup 2}. We have achieved high resolution point projection 1-dimensional and 2-dimensional radiography using micro-foil and micro-wire targets attached to low-Z substrate materials. The micro-wire size was 10 {micro}m x 10 {micro}m x 300 {micro}m on a 300 {micro}m x 300 {micro}m x 5 {micro}m CH substrate. The radiography performance was demonstrated using the Titan laser at LLNL. We observed that the resolution is dominated by the micro-wire target size and there is very little degradation from the plasma plume, implying that the high energy x-ray photons are generated mostly within the micro-wire volume. We also observe that there are enough K{alpha} photons created with a 300 J, 1-{omega}, 40 ps pulse laser from these small volume targets, and that the signal-to-noise ratio is sufficiently high, for single shot radiography experiments. This unique technique will be used on future high energy density (HED) experiments at the new Omega-EP, ZR and NIF facilities.

  7. 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 μm thick and newly developed 450 μm and 1000 μm 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 μm2). 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.

  8. Experimental Determination of the HPGe Spectrometer Efficiency Calibration Curves for Various Sample Geometry for Gamma Energy from 50 keV to 2000 keV

    NASA Astrophysics Data System (ADS)

    Saat, Ahmad; Hamzah, Zaini; Yusop, Mohammad Fariz; Zainal, Muhd Amiruddin

    2010-07-01

    Detection efficiency of a gamma-ray spectrometry system is dependent upon among others, energy, sample and detector geometry, volume and density of the samples. In the present study the efficiency calibration curves of newly acquired (August 2008) HPGe gamma-ray spectrometry system was carried out for four sample container geometries, namely Marinelli beaker, disc, cylindrical beaker and vial, normally used for activity determination of gamma-ray from environmental samples. Calibration standards were prepared by using known amount of analytical grade uranium trioxide ore, homogenized in plain flour into the respective containers. The ore produces gamma-rays of energy ranging from 53 keV to 1001 keV. Analytical grade potassium chloride were prepared to determine detection efficiency of 1460 keV gamma-ray emitted by potassium isotope K-40. Plots of detection efficiency against gamma-ray energy for the four sample geometries were found to fit smoothly to a general form of ɛ = AΕa+BΕb, where ɛ is efficiency, Ε is energy in keV, A, B, a and b are constants that are dependent on the sample geometries. All calibration curves showed the presence of a "knee" at about 180 keV. Comparison between the four geometries showed that the efficiency of Marinelli beaker is higher than cylindrical beaker and vial, while cylindrical disk showed the lowest.

  9. Experimental Determination of the HPGe Spectrometer Efficiency Calibration Curves for Various Sample Geometry for Gamma Energy from 50 keV to 2000 keV

    SciTech Connect

    Saat, Ahmad; Hamzah, Zaini; Yusop, Mohammad Fariz; Zainal, Muhd Amiruddin

    2010-07-07

    Detection efficiency of a gamma-ray spectrometry system is dependent upon among others, energy, sample and detector geometry, volume and density of the samples. In the present study the efficiency calibration curves of newly acquired (August 2008) HPGe gamma-ray spectrometry system was carried out for four sample container geometries, namely Marinelli beaker, disc, cylindrical beaker and vial, normally used for activity determination of gamma-ray from environmental samples. Calibration standards were prepared by using known amount of analytical grade uranium trioxide ore, homogenized in plain flour into the respective containers. The ore produces gamma-rays of energy ranging from 53 keV to 1001 keV. Analytical grade potassium chloride were prepared to determine detection efficiency of 1460 keV gamma-ray emitted by potassium isotope K-40. Plots of detection efficiency against gamma-ray energy for the four sample geometries were found to fit smoothly to a general form of {epsilon} = A{Epsilon}{sup a}+B{Epsilon}{sup b}, where {epsilon} is efficiency, {Epsilon} is energy in keV, A, B, a and b are constants that are dependent on the sample geometries. All calibration curves showed the presence of a ''knee'' at about 180 keV. Comparison between the four geometries showed that the efficiency of Marinelli beaker is higher than cylindrical beaker and vial, while cylindrical disk showed the lowest.

  10. sup 56 Fe resonance parameters for neutron energies up to 850 keV

    SciTech Connect

    Perey, C.M.; Perey, F.G.; Harvey, J.A.; Hill, N.W.; Larson, N.M.

    1990-12-01

    High-resolution neutron measurements for {sup 56}Fe-enriched iron targets were made at the Oak Ridge Electron Linear Accelerator (ORELA) in transmission below 20 MeV and in differential elastic scattering below 5 MeV. Transmission measurements were also performed with a natural iron target below 160 keV. The transmission data were analyzed from 5 to 850 keV with the multilevel R-matrix code SAMMY which uses Bayes' theorem for the fitting process. This code provides energies and neutron widths of the resonances inside the 5- to 850-keV energy region, as well as possible parameterization for resonances external to the analyzed region to describe the smooth cross section from a few eV to 850 keV. The resulting set of resonance parameters yields the accepted values for the thermal total and capture cross sections. The differential elastic-scattering data at several scattering angles were compared to theoretical calculations from 40 to 850 keV using the R-matrix code RFUNC based on the Blatt-Biedenharn formalism. Various combinations of spin and parity were tried to predict cross sections for the well defined {ell} > 0 resonances; comparison of these predictions with the data allowed us to determine the most likely spin and parity assignments for these resonances. The results of a capture data analysis by Corvi et al. (COR84), from 2 to 350 keV, were combined with our results to obtain the radiation widths of the resonances below 350 keV observed in transmission, capture, and differential elastic-scattering experiments.

  11. High-energy recoil-ion emission in keV heavy-ion surface collisions

    NASA Astrophysics Data System (ADS)

    van Someren, B.; Rudolph, H.; Urazgil'din, I. F.; van Emmichoven, P. A. Zeijlmans; Niehaus, A.

    1997-11-01

    For keV Xe +, Kr + and Ar + ions incident at 30° on Cu(110) we have observed the emission of negatively charged particles with energies up to about 40% of the primary energy. By time-of-flight techniques we have found that electrons are emitted with energies up to 80 eV, whereas the negatively charged high-energy particles are Cu - recoil ions. High-energy Cu + ions have also been found. Simple energy and momentum conservation arguments show that such high recoil energies are indeed possible for multiple collision events in which the primary recoil ion scatters off one or more Cu atoms.

  12. Energy loss of tens keV charged particles traveling in the hot dense carbon plasma

    NASA Astrophysics Data System (ADS)

    Fu, ZhenGuo; Wang, ZhiGang; He, Bin; Li, DaFang; Zhang, Ping

    2016-08-01

    The energy loss of charged particles, including electrons, protons, and α-particles with tens keV initial energy E 0, traveling in the hot dense carbon (C) plasma for densities from 2.281 to 22.81 g/cm3 and temperatures from 400 to 1500 eV is systematically and quantitatively studied by using the dimensional continuation method. The behaviors of different charged particles are readily distinguishable from each other. Firstly, because an ion is thousands times heavier than an electron, the penetration distance of the electron is much longer than that of proton and α-particle traveling in the plasma. Secondly, most energy of electron projectile with E 0 < 100 keV deposits into the electron species of C plasma, while for the cases of proton and α-particle with E 0 < 100 keV, about more than half energy transfers into the ion species of C plasma. A simple decreasing law of the penetration distance as a function of the plasma density is fitted, and different behaviors of each projectile particle can be clearly found from the fitted data. We believe that with the advanced progress of the present experimental technology, the findings shown here could be confirmed in ion-stopping experiments in the near future.

  13. Tuning of wettability of PANI-GNP composites using keV energy ions

    NASA Astrophysics Data System (ADS)

    Lakshmi, G. B. V. S.; Avasthi, D. K.

    2016-07-01

    Polyaniline nanofiber composites with various nanomaterials have several applications in electrochemical biosensors. The surface properties of these composites coated electrodes play crucial role in enzyme absorption and analyte detection process. In the present study, Polyaniline-Graphene nanopowder (PANI-GNP) composites were prepared by rapid-mixing polymerization method. The films were prepared on ITO coated glass substrates and irradiated with 42 keV He+ ions produced by indigenously fabricated accelerator at IUAC, New Delhi. The films were characterized before and after irradiation by SEM, Raman spectroscopy and contact angle measurements. The as-prepared films show superhydrophilic nature and after irradiation the films show highly hydrophobic nature with water contact angle (135°). The surface morphology was studied by SEM and structural changes were studied by Raman spectra. The surface morphological modifications induced by keV energy ions helps in tuning the wettability at different ion fluences.

  14. Auroral electrons of energy less than 1 keV observed at rocket altitudes.

    NASA Technical Reports Server (NTRS)

    Arnoldy, R. L.; Choy, L. W.

    1973-01-01

    Measurements of electrons of energy less than 1 keV in the auroral precipitation with detectors aboard three rocket flights are discussed. Detectors simultaneously measured the flux of electrons moving up and down the magnetic field lines. Electrons of energy less than a few hundred electron volts show directional intensities ranging from isotropic over the upper hemisphere, to field aligned into the atmosphere, to a net streaming out of the atmosphere. Cases of reflection coefficients greater than 1 for the few hundred electron volts and lower-energy electrons occur when measurements were made north of auroral forms. These electrons might represent the high-energy tail of the return Birkeland currents. The origin of the low-energy electrons is itself in question.

  15. A neutron spectrometer for neutron energies between 1 eV and 10 keV

    SciTech Connect

    Wang, C.K.; Blue, T.E.

    1988-01-01

    In boron neutron capture therapy (BNCT), it is the consensus that epithermal neutron beams have advantages over thermal beams in treating deep-seated brain tumors, and large neutron fields have advantages over narrow beams, since whole-brain irradiations are thought to be necessary in many cases. Epithermal neutron sources for BNCT, which include filtered reactor neutron beams and moderated reactor neutron fields, are currently being developed at many institutions around the world. Neutrons with energies between 1 eV and 10 keV are most suitable for treating brain tumors. However, techniques for measuring neutron spectra in a vacuum in this energy range are not well developed. This paper describes a new type of neutron spectrometer that has a set of response functions that peak at equally spaced intervals on a logarithmic energy scale ranging from 1 eV to 10 keV; therefore, neutron spectra (or histograms) in this energy range can be obtained by properly applying spectrum unfolding techniques to the measured data. The spectrometer is applicable for measurements in a vacuum for both narrow neutron beams and wide neutron fields.

  16. Evaluation of Silicon Neutron Resonance Parameters in the Energy Range Thermal to 1800 keV

    SciTech Connect

    Derrien, H.

    2002-09-30

    The evaluation of the neutron cross sections of the three stable isotopes of silicon in the energy range thermal to 20 MeV was performed by Hetrick et al. for ENDF/B-VI (Evaluated Nuclear Data File). Resonance parameters were obtained in the energy range thermal to 1500 keV from a SAMMY analysis of the Oak Ridge National Laboratory experimental neutron transmission data. A new measurement of the capture cross section of natural silicon in the energy range 1 to 700 keV has recently been performed at the Oak Ridge Electron Linear Accelerator. Results of this measurement were used in a SAMMY reevaluation of the resonance parameters, allowing determination of the capture width of a large number of resonances. The experimental data base is described; properties of the resonance parameters are given. For the first time the direct neutron capture component has been taken into account from the calculation by Rauscher et al. in the energy range from thermal to 1 MeV. Results of benchmark calculations are also given. The new evaluation is available in the ENDF/B-VI format.

  17. Attenuation of photons at 3 to 14 keV energies in helium

    SciTech Connect

    Azuma, Y.; Berry, H.G.; Gemmell, D.S.

    1995-08-01

    Using X-ray photons at the X24A, X23B and X23A2 beam lines at NSLS, we measured the total photo-attenuation cross section of helium for photons in the energy range of 3 to 14 keV. In this range the photoionization cross section decreases rapidly with energy, so that Compton scattering is significant at 4 keV and dominates at the highest energies. The apparatus consisted of a 1.4-m long helium-absorption tube, 5 cm in diameter, with 75-{mu} thick, 7-mm diameter, kapton end windows. The tube could be filled with helium up to a pressure of 10{sup 6} Pa. We attained a precision of 1-2% in the attenuation cross section. The measurements verify the dominance of Compton scattering in this energy range and its importance in recent measurements of the ratio of double-to-single photoionization of helium. The measured cross sections are close to the combined calculated cross sections for Compton scattering and photoionization, and we are able to distinguish the contributions of the two effects.

  18. X-ray grating interferometry at photon energies over 180 keV

    NASA Astrophysics Data System (ADS)

    Ruiz-Yaniz, M.; Koch, F.; Zanette, I.; Rack, A.; Meyer, P.; Kunka, D.; Hipp, A.; Mohr, J.; Pfeiffer, F.

    2015-04-01

    We report on the implementation and characterization of grating interferometry operating at an x-ray energy of 183 keV. With the possibility to use this technique at high x-ray energies, bigger specimens could be studied in a quantitative way. Also, imaging strongly absorbing specimens will benefit from the advantages of the phase and dark-field signals provided by grating interferometry. However, especially at these high photon energies the performance of the absorption grating becomes a key point on the quality of the system, because the grating lines need to keep their small width of a couple of micrometers and exhibit a greater height of hundreds of micrometers. The performance of high aspect ratio absorption gratings fabricated with different techniques is discussed. Further, a dark-field image of an alkaline multicell battery highlights the potential of high energy x-ray grating based imaging.

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

    SciTech Connect

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

    2007-01-19

    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.

  20. 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.

  1. NEUTRON TOTAL CROSS SECTIONS OF 235U FROM TRANSMISSION MEASUREMENTS IN THE ENERGY RANGE 2 keV to 300 keV AND STATISTICAL MODEL ANALYSIS OF THE DATA

    SciTech Connect

    Derrien, H.

    2000-05-22

    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. 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. 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 was used for a statistical model analysis of the total cross section, selected fission cross sections and {alpha} 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 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.

  2. Characterisation of a counting imaging detector for electron detection in the energy range 10-20 keV

    NASA Astrophysics Data System (ADS)

    Moldovan, G.; Sikharulidze, I.; Matheson, J.; Derbyshire, G.; Kirkland, A. I.; Abrahams, J. P.

    2012-07-01

    As part of a feasibility study into the use of novel electron detector for X-ray photoelectron emission microscopes (XPEEM) and related methods, we have characterised the imaging performance of a counting Medipix 2 readout chip bump bonded to a Silicon diode array sensor and directly exposed to electrons in the energy range 10-20 keV. Detective Quantum Efficiency (DQE), Modulation Transfer Function (MTF) and Noise Power Spectra (NPS) are presented, demonstrating very good performance for the case of electrons with an energy of 20 keV. Significant reductions in DQE are observed for electrons with energy of 15 keV and less, down to levels of 20% for electrons of 10 keV.

  3. Evaluation of silicon neutron resonance parameters in the thermal to 1800 keV energy range.

    PubMed

    Derrien, H; Leal, L C; Guber, K H; Larson, N M

    2005-01-01

    Because silicon is a major constituent of concrete and soil, neutron and gamma ray information on silicon is important for reactor shielding and criticality safety calculations. Therefore, much effort was put into the ENDF/B-VI evaluation for the three stable isotopes of silicon. The neutron capture cross section of natural silicon was recently measured at the Oak Ridge Electron Linear Accelerator (ORELA) in the energy range 1-700 keV. Using the ENDF/B-VI evaluation for initial values, a new evaluation of the resonance parameters was performed by adding the results of the ORELA capture measurements to the experimental database. The computer code SAMMY was used for the analysis of the experimental data; the new version of SAMMY allows accurate calculations of the self-shielding and multiple scattering effects in the capture measurements. The accuracy of the radiative capture widths of the resonances was improved by this analysis. Accurate values of the s-, p- and d-wave neutron strength functions were also obtained. Although the resonance capture component of the present evaluation is 2-3 times smaller than that in ENDF/B-VI, the total capture cross section is much larger, at least for energies >250 keV, because the direct capture component contributes values of the same order of magnitude as the resonance component. The direct component was not taken into account in the ENDF/B-VI evaluation and was calculated for the first time in the present evaluation. PMID:16381717

  4. 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.

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

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  6. Stochastic spatial energy deposition profiles for MeV protons and keV electrons

    NASA Astrophysics Data System (ADS)

    Udalagama, C.; Bettiol, A. A.; Watt, F.

    2009-12-01

    With the rapid advances being made in novel high-energy ion-beam techniques such as proton beam writing, single-ion-event effects, ion-beam-radiation therapy, ion-induced fluorescence imaging, proton/ion microscopy, and ion-induced electron imaging, it is becoming increasingly important to understand the spatial energy-deposition profiles of energetic ions as they penetrate matter. In this work we present the results of comprehensive yet straightforward event-by-event Monte Carlo calculations that simulate ion/electron propagation and secondary electron ( δ ray) generation to yield spatial energy-deposition data. These calculations combine SRIM/TRIM features, EEDL97 data and volume-plasmon-localization models with a modified version of one of the newer δ ray generation models, namely, the Hansen-Kocbach-Stolterfoht. The development of the computer code DEEP (deposition of energy due to electrons and protons) offers a unique means of studying the energy-deposition/redistribution problem while still retaining the important stochastic nature inherent in these processes which cannot be achieved with analytical modeling. As an example of an application of DEEP we present results that compare the energy-deposition profiles of primary MeV protons and primary keV electrons in polymethymethacrylate. Such data are important when comparing proximity effects in the direct write lithography processes of proton-beam writing and electron-beam writing. Our calculations demonstrate that protons are able to maintain highly compact spatial energy-deposition profiles compared with electrons.

  7. Low-energy x-ray dosimetry studies (6 to 16 keV) at SSRL beamline 1-5

    NASA Astrophysics Data System (ADS)

    Ipe, N. E.; Chatterji, S.; Fassò, A.; Kase, K. R.; Seefred, R.; Olko, P.; Bilski, P.; Soares, C.

    1997-07-01

    Synchrotron radiation facilities provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory (SSRL) are described. Polish lithium fluoride thermoluminescent dosemeters (TLDs), MTS-N(LiF:Mg, Ti- 0.4 mm thick), MCP-N (LiF:Mg, Cu, P - 0.4 mm thick) were exposed free in air to monochromatic x-rays (6-16 keV). These exposures were monitored with an SSRL ionization chamber. The responses (counts/Gy) of MTS-N and MCP-N were generally found to increase with increasing energy. The response at 16 keV is about 3 and 4 times higher than the response at 6 keV for MTS-N and MCP-N, respectively. Irradiation at 6 keV indicates a fairly linear dose response for both type of TLDs over a dose range of 0.01 to 0.4 Gy. In addition there appears to be no significant difference in responses between irradiating the TLDs from the front and the back sides. The energy response of the PTW ionization chamber type 23342 relative to the SSRL ionization chamber is within ±4.5% between 6 and 16 keV. Both the TLDs and the PTW ionization chamber can also be used for beam dosimetry.

  8. Imager of low energy neutral atoms (ILENA) - Imaging neutrals from the magnetosphere at energies below 20 keV

    NASA Technical Reports Server (NTRS)

    Herrero, Federico A.; Smith, Mark F.

    1992-01-01

    We describe a new imager suitable for measurements of magnetospheric neutrals with energies from about 100 eV to about 10 keV; an energy range adequate for imaging the plasmasheet neutral atoms out to about 10 R(E). The instrument, an outgrowth of a study of atom-surface collisions in support of satellite drag calculations, separates incident photons from neutral atoms by surface scattering and conversion of the neutrals to ions. Subsequently, the ions formed on the first surface are accelerated through a light rejection section which also disperses the ions according to energy. The dispersed ion beam is then allowed to impact a second surface where a start pulse is generated to obtain ion velocity and energy/charge. The second surface is chosen to give large secondary electron emission without regard to charge state of the particles reflected from it. The data supporting the proposed ILENA design is presented in the first part of the paper.

  9. Cross section for induced L X-ray emission by protons of energy <400 keV

    NASA Astrophysics Data System (ADS)

    Mohan, Harsh; Jain, Arvind Kumar; Kaur, Mandeep; Singh, Parjit S.; Sharma, Sunita

    2014-08-01

    In performing ion beam analysis, cross section for induced L X-ray emission plays a crucial role. There are different approaches by which these can be found experimentally or can be calculated theoretically based on various models. L X-ray production cross sections for Bi with protons in the energy range 260-400 keV at the interval of 20 keV are measured. These are compared with calculations obtained on the basis of current prevailing theories ECPSSR and ECPSSR-UA. Their importance in understanding this phenomenon and existing arguments in this regard will be highlighted.

  10. The energy spectrum of 20 keV-20 MeV electrons accelerated in large solar flares

    NASA Technical Reports Server (NTRS)

    Lin, R. P.; Mewaldt, R. A.; Van Hollebeke, M. A. I.

    1982-01-01

    IMP 6, 7, and 8 measurements of the energy spectrum of 20 keV to 20 MeV electrons observed from large solar flares are presented. To minimize propagation effects, only events from flares at W30 deg to W90 deg solar longitude are considered. The energy spectra are constructed using the maximum flux observed at each energy. It is shown that these spectra are representative of the spectra of the electrons escaping from the sun over this range of energies. It is found that every event shows the same spectral shape: a double power law with a smooth transition around 100-200 keV and power law exponents of 0.6-2.0 below and 2.4-4.3 above. The more intense the event, the harder the observed spectrum; in certain cases, the spectra are observed to steepen above 3 MeV.

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

    SciTech Connect

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

    2006-06-14

    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 of 1-4%. However, the difference between these data and those based on R-matrix analysis and used in the ENDF libraries is evident, especially in the energy range 1-60 keV. Experimental data for total scattering neutron cross sections for this element in the energy range 1-200 keV are scanty. The use of the technique of neutron filtered beams developed at the Kyiv Research Reactor makes it possible to reduce the uncertainty of the experimental data and to measure the neutron scattering cross sections on natural carbon in the energy range 2-149 keV with accuracies of 3-6%. Investigations of the neutron scattering cross section on carbon were carried out using 5 filters with energies 2, 3.5, 24, 54 and 133 keV. The neutron scattering cross sections were measured using a detector system covering nearly 2{pi}. The detector consisting of {sup 3}He counters (58 units), was located just above the carbon samples. The {sup 3}He counters (CHM-37, 7 atm, diameter =18 mm, L=50 cm) are placed in five layers (12 or 11 in each layer). To determine the neutron scattering cross section on carbon the relative method of measurement was used. The isotope {sup 208}Pb was used as the standard. The normalization factor, which is a function of detector efficiency, thickness of the carbon samples, thickness of the {sup 208}Pb sample, geometry, etc., for each sample and for each filter energy has been obtained through Monte Carlo calculations by means of the MCNP4C code. The results of measurements of the neutron scattering cross sections at reactor neutron filtered beams with energies in the range 2-133 keV on

  12. 5 to 160 keV continuous-wave x-ray spectral energy distribution and energy flux density measurements

    SciTech Connect

    Tallon, R.W.; Koller, D.C.; Pelzl, R.M.; Pugh, R.D.; Bellem, R.D. . Microelectronics and Photonics Research Branch)

    1994-12-01

    In 1991, the USAF Phillips Laboratory Microelectronics and Photonics Research Branch installed a low energy x-ray facility (LEXR) for use in microelectronics radiation-effects analysis and research. Techniques developed for measuring the x-ray spectral energy distribution (differential intensity) from a tungsten-target bremsstrahlung x-ray source are reported. Spectra with end-point energies ranging from 20 to 160 keV were recorded. A separate effort to calibrate the dosimetry for the Phillips Laboratory low-energy x-ray facility established a need to know the spectral energy distributions at some point within the facility (previous calibration efforts had relies on spectra obtained from computer simulations). It was discovered that the primary discrepancy between the simulated and measured spectra was in the L- K-line data. The associated intensity (energy flux density) of the measured distributions was found to be up to 30% higher. Based on the measured distributions, predicted device responses were within 10% of the measured response as compared to about 30% accuracy obtained with simulated distributions.

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

    SciTech Connect

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

    2009-04-15

    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 {sigma}{sub 0} = 20.428(16) b, which is in very good agreement with a value of {sigma}{sub 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 {sigma}{sub 0} = 20.491(14) b lead to calculated cross sections whose values are in excess of their experimental counterparts.

  14. 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 σ 0 = 20.428(16) b, which is in very good agreement with a value of σ 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 σ 0 = 20.491(14) b lead to calculated cross sections whose values are in excess of their experimental counterparts.

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

    NASA Astrophysics Data System (ADS)

    Windt, David L.; Donguy, Soizik; Hailey, Charles J.; Koglin, Jason E.; Honkimaki, Veijo; Ziegler, Eric; Christensen, Finn E.; Harrison, Fiona A.

    2004-02-01

    We have determined experimentally optical constants for eight thin film materials that can be used in hard X-ray multilayer coatings. Thin film samples of Ni.97V.03, Mo, W, Pt, C, B4C, Si and SiC were deposited by magnetron sputtering onto superpolished optical flats. Optical constants were determined from fits to reflectance-vs-incidence angle measurements made using synchrotron radiation over the energy range E=35 180 keV. We have also measured the X-ray reflectance of a prototype W/SiC multilayer coating over the energy range E=35 100 keV, and we compare the measured reflectance with a calculation using the newly derived optical constants.

  16. Studies on effective atomic numbers for photon energy absorption and electron density of some narcotic drugs in the energy range 1 keV-20 MeV

    NASA Astrophysics Data System (ADS)

    Gounhalli, Shivraj G.; Shantappa, Anil; Hanagodimath, S. M.

    2013-04-01

    Effective atomic numbers for photon energy absorption ZPEA,eff, photon interaction ZPI,eff and for electron density Nel, have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for narcotic drugs, such as Heroin (H), Cocaine (CO), Caffeine (CA), Tetrahydrocannabinol (THC), Cannabinol (CBD), Tetrahydrocannabivarin (THCV). The ZPEA,eff, ZPI,eff and Nel values have been found to change with energy and composition of the narcotic drugs. The energy dependence ZPEA,eff, ZPI,eff and Nel is shown graphically. The maximum difference between the values of ZPEA,eff, and ZPI,eff occurs at 30 keV and the significant difference of 2 to 33% for the energy region 5-100 keV for all drugs. The reason for these differences is discussed.

  17. Self-attenuation correction factors for bioindicators measured by γ spectrometry for energies <100 keV

    NASA Astrophysics Data System (ADS)

    Manduci, L.; Tenailleau, L.; Trolet, J. L.; De Vismes, A.; Lopez, G.; Piccione, M.

    2010-01-01

    The mass attenuation coefficients for a number of marine and terrestrial bioindicators were measured using γ spectrometry for energies between 22 and 80 keV. These values were then used to find the correction factor k for the apparent radioactivity. The experimental results were compared with a Monte Carlo simulation performed using PENELOPE in order to evaluate the reliability of the simplified calculation and to determine the correction factors.

  18. Novel Method to Study Neutron Capture of U235 and U238 Simultaneously at keV Energies

    NASA Astrophysics Data System (ADS)

    Wallner, A.; Belgya, T.; Bichler, M.; Buczak, K.; Dillmann, I.; Käppeler, F.; Lederer, C.; Mengoni, A.; Quinto, F.; Steier, P.; Szentmiklosi, L.

    2014-05-01

    The neutron capture cross sections of the main uranium isotopes, U235 and U238, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT ˜25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of U235(n ,γ)/U238(n ,γ) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products U236/U239, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies.

  19. Novel method to study neutron capture of 235U and 238U simultaneously at keV energies.

    PubMed

    Wallner, A; Belgya, T; Bichler, M; Buczak, K; Dillmann, I; Käppeler, F; Lederer, C; Mengoni, A; Quinto, F; Steier, P; Szentmiklosi, L

    2014-05-16

    The neutron capture cross sections of the main uranium isotopes, (235)U and (238)U, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT ∼ 25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of (235)U(n,γ)/(238)U(n,γ) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products (236)U/(239)U, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies. PMID:24877933

  20. Improved energy of the 21.5 keV M1 + E2 nuclear transition in 151Eu

    NASA Astrophysics Data System (ADS)

    Inoyatov, A. Kh.; Kovalík, A.; Filosofov, D. V.; Ryšavý, M.; Perevoshchikov, L. L.; Baimukhanova, A.

    2016-05-01

    Using internal conversion electron spectroscopy, improved energy 21 541.5±0.5 eV was determined for the 21.5keV M1 + E2 nuclear transition in 151Eu populated in the electron capture decay of 151Gd . This value was found to agree well with the present adopted value but is much more accurate. A value of 0.0305±0.0011 derived for the E2 admixture parameter \\vertδ(E2/M1)\\vert from the measured conversion electron line intensities corresponds to the present adopted value. A possible effect of nuclear structure on the multipolarity of the 21.5 keV transition was also investigated.

  1. Neutron total cross section measurements in the energy region from 47 keV to 20 MeV

    SciTech Connect

    Poenitz, W.P.; Whalen, J.F.

    1983-05-01

    Neutron total cross sections were measured for 26 elements. Data were obtained in the energy range from 47 keV to 20 MeV for 11 elements in the range of light-mass fission products. Previously reported measurements for eight heavy and actinide isotopes were extended to 20 MeV. Data were also obtained for Cu (47 keV to 1.4 MeV) and for Sc, Zn, Nd, Hf, and Pt (1.8 to 20 MeV). The present work is part of a continuing effort to provide accurate neutron total cross sections for evaluations and for optical-model parameteriztions. The latter are required for the derivation of other nuclear-data information of importance to applied programs. 37 references.

  2. 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.

  3. Sub-second variations of high energy ( 300 keV) hard X-ray emission from solar flares

    NASA Technical Reports Server (NTRS)

    Bai, Taeil

    1986-01-01

    Subsecond variations of hard X-ray emission from solar flares were first observed with a balloon-borne detector. With the launch of the Solar Maximum Mission (SMM), it is now well known that subsecond variations of hard X-ray emission occur quite frequently. Such rapid variations give constraints on the modeling of electron energization. Such rapid variations reported until now, however, were observed at relatively low energies. Fast mode data obtained by the Hard X-ray Burst Spectrometer (HXRBS) has time resolution of approximately 1 ms but has no energy resolution. Therefore, rapid fluctuations observed in the fast-mode HXRBS data are dominated by the low energy hard X-rays. It is of interest to know whether rapid fluctuations are observed in high-energy X-rays. The highest energy band at which subsecond variations were observed is 223 to 1057 keV. Subsecond variations observed with HXRBS at energies greater than 300 keV are reported, and the implications discussed.

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

    SciTech Connect

    Naqvi, A.A.; Ayer, Z.; Ludwig, E. ||

    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.

  5. Low-energy x-ray dosimetry studies (7 to 17.5 keV) with synchroton radiation

    SciTech Connect

    Ipe, N.E.; Bellamy, H.; Flood, J.R.

    1995-06-01

    Unique properties of synchrotron radiation (SR), such as its high intensity, brightness, polarization, and broad spectral distribution (extending from x-ray to infra-red wavelengths) make it an attractive light source for numerous experiments. As SR facilities are rapidly being built all over the world, they introduce the need for low-energy x-ray dosemeters because of the potential radiation exposure to experimenters. However, they also provide a unique opportunity for low-energy x-ray dosimetry studies because of the availability of monochromatic x-ray beams. Results of such studies performed at the Stanford Synchrotron Radiation Laboratory are described. Lithium fluoride TLDs (TLD-100) of varying thicknesses (0.015 to 0.08 cm) were exposed free in air to monochromatic x-rays (7 to 17.5 keV). These exposures were monitored with ionization chambers. The response (nC/Gy) was found to increase with increasing TLD thickness and with increasing beam energy. A steeper increase in response with increasing energy was observed with the thicker TLDs. The responses at 7 and 17.5 keV were within a factor of 2.3 and 5.2 for the 0.015 and 0.08 cm-thick TLDs, respectively. The effects of narrow (beam size smaller than the dosemeter) and broad (beam size larger than the dosemeter) beams on the response of the TLDs are also reported.

  6. 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.

  7. A high-resolution time-of-flight energy analyzer for femtosecond electron pulses at 30 keV

    NASA Astrophysics Data System (ADS)

    Gliserin, Alexander; Walbran, Matthew; Baum, Peter

    2016-03-01

    We report a time-of-flight spectrometer for electron pulses at up to 30 keV, which is a suitable energy for atomic-resolution femtosecond investigations via time-resolved electron diffraction, microscopy, and energy loss spectroscopy. For realistic femtosecond beams without apertures, the instrument's energy resolution is ˜0.5 eV (full width at half maximum) or 2 × 10-5 at a throughput of 50%-90%. We demonstrate the analyzer's versatility by three first applications, namely, femtosecond electron pulse metrology via optical streaking, in situ drift correction in laser-microwave synchronization for electron pulse compression, and time-resolved electron energy loss spectroscopy of aluminum, showing the instrument's capability of tracking plasmonic loss peak positions with few-meV accuracy.

  8. A high-resolution time-of-flight energy analyzer for femtosecond electron pulses at 30 keV.

    PubMed

    Gliserin, Alexander; Walbran, Matthew; Baum, Peter

    2016-03-01

    We report a time-of-flight spectrometer for electron pulses at up to 30 keV, which is a suitable energy for atomic-resolution femtosecond investigations via time-resolved electron diffraction, microscopy, and energy loss spectroscopy. For realistic femtosecond beams without apertures, the instrument's energy resolution is ∼0.5 eV (full width at half maximum) or 2 × 10(-5) at a throughput of 50%-90%. We demonstrate the analyzer's versatility by three first applications, namely, femtosecond electron pulse metrology via optical streaking, in situ drift correction in laser-microwave synchronization for electron pulse compression, and time-resolved electron energy loss spectroscopy of aluminum, showing the instrument's capability of tracking plasmonic loss peak positions with few-meV accuracy. PMID:27036767

  9. Frequency of occurrence of LCS per cascade in bcc iron by PKA energy 30 keV

    NASA Astrophysics Data System (ADS)

    Elias, A.; Driss Khodja, M.

    2009-11-01

    The frequency of occurrence per cascade in bcc iron is studied by PKA energy 30keV using the fitting of potentials on linear collision sequences (LCS). Two embedded atom potentials that essentially differ by their repulsive branches are used in classical molecular dynamic (MD) with the code DYMOKA and its binary collision approximation (BCA) The Molière and Born Mayer potentials are used in the Binary Collision Approximation (BCA). The linear collision sequences (LCS) in iron can be generated with Marlowe code in BCA, using the potentials parameters. The BCA is used to accumulate cascade statistics and to build linear collision sequences distributions.

  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. Mass attenuation coefficients of soil and sediment samples using gamma energies from 46.5 to 1332 keV.

    PubMed

    Al-Masri, M S; Hasan, M; Al-Hamwi, A; Amin, Y; Doubal, A W

    2013-02-01

    Mass attenuation coefficients of various soil and sediment samples (density range between 1.0 and 1.7 g cm(-3)) collected from 60 sites distributed in Syrian land have been determined for gamma lines of 46.5, 59.5, 88, 122, 165, 392, 661, 1173, and 1332 keV using gamma spectrometry and simulation software program X-com. The average mass attenuation coefficients for the studied samples were found to be 0.513, 0.316, 0.195, 0.155, 0.134, 0.096, 0.077, 0.058, and 0.055 cm(2) g(-1) at previous energies, respectively. The results have shown that Ca and Fe contents of the samples have strong effect on the mass attenuation coefficient at lower energies. In addition, self-attenuation correction factors determined using mass attenuation coefficient was in good agreement with addition spiked reference material method provided that the sample thickness is 2.7 cm. However, mass attenuation coefficients determined in this study can be used for determination of gamma emitters at energy ranges from 46.5 to 1332 keV in any soil and sediment samples having density of 1.0-1.7 g cm(-3). PMID:23103572

  12. Experimental investigation of the multiple scatter peak of gamma rays in portland cement in the energy range 279-1332 keV

    NASA Astrophysics Data System (ADS)

    Singh, Tejbir; Singh, Parjit S.

    2011-12-01

    The pulse height spectra for different thicknesses of portland cement in the reflected geometry has been recorded with the help of a NaI(Tl) scintillator detector and 2 K MCA card using different gamma-ray sources such as Hg203 (279 keV), Cs137 (662 keV) and Co60 (1173 and 1332 keV). It has been observed that the multiple scatter peak for portland cement appears at 110 (±7) keV in all the spectra irrespective of different incident photon energies in the range 279-1332 keV from different gamma-ray sources. Further, the variation in the intensity of the multiple scatter peak with the thickness of portland cement in the backward semi-cylinders has been investigated.

  13. Improving the energy response of external beam therapy (EBT) GafChromic{sup TM} dosimetry films at low energies (≤100 keV)

    SciTech Connect

    Bekerat, H. Devic, S.; DeBlois, F.; Singh, K.; Sarfehnia, A.; Seuntjens, J.; Shih, Shelley; Yu, Xiang; Lewis, D.

    2014-02-15

    Purpose: Purpose of this work is to investigate the effects of varying the active layer composition of external beam therapy (EBT) GafChromic{sup TM} films on the energy dependence of the film, as well as try to develop a new prototype with more uniform energy response at low photon energies (⩽100 keV). Methods: First, the overall energy response (S{sub AD,} {sub W}(Q)) of different commercial EBT type film models that represent the three different generations produced to date, i.e., EBT, EBT2, and EBT3, was investigated. Pieces of each film model were irradiated to a fixed dose of 2 Gy to water for a wide range of beam qualities and the corresponding S{sub AD,} {sub W}(Q) was measured using a flatbed document scanner. Furthermore, the DOSRZnrc Monte Carlo code was used to determine the absorbed dose to water energy dependence of the film, f(Q). Moreover, the intrinsic energy dependence, k{sub bq}(Q), for each film model was evaluated using the corresponding S{sub AD,} {sub W}(Q) and f(Q). In the second part of this study, the authors investigated the effects of changing the chemical composition of the active layer on S{sub AD,} {sub W}(Q). Finally, based on these results, the film manufacturer fabricated several film prototypes and the authors evaluated their S{sub AD,} {sub W}(Q). Results: The commercial EBT film model shows an under response at all energies below 100 keV reaching 39% ± 4% at about 20 keV. The commercial EBT2 and EBT3 film models show an under response of about 27% ± 4% at 20 keV and an over response of about 16% ± 4% at 40 keV.S{sub AD,} {sub W}(Q) of the three commercial film models at low energies show strong correlation with the corresponding f{sup −1}(Q) curves. The commercial EBT3 model with 4% Cl in the active layer shows under response of 22% ± 4% at 20 keV and 6% ± 4% at about 40 keV. However, increasing the mass percent of chlorine makes the film more hygroscopic which may affect the stability of the film's readout. The

  14. Measurement of low energy neutron spectrum below 10 keV with the slowing down time method

    NASA Astrophysics Data System (ADS)

    Maekawa, F.; Oyama, Y.

    1996-02-01

    No general-purpose method of neutron spectrum measurement in the energy region around eV has been established so far. Neutron spectrum measurement in this energy region was attempted by applying the slowing down time (SDT) method, for the first time, inside two types of shield for fusion reactors, type 316 stainless steel (SS316) and SS316/water layered assemblies, incorporating with pulsed neutrons. In the SS316 assembly, neutron spectra below 1 keV were measured with an accuracy less than 10%. Although application of the SDT method was expected very difficult for SS316/water assembly since it contained lightest atoms of hydrogen, the measurement demonstrated that the SDT method was still effective for such shield assembly. The SDT method was also extended to thermal flux measurement in the SS316/water assembly. The present study demonstrated that the SDT method was effective for neutron spectrum measurement in the energy region around eV.

  15. Suppression of repetitive surface exfoliation of Inconel 625 implanted sequentially with helium ions of different energies (20 100 keV)

    NASA Astrophysics Data System (ADS)

    Rao, A. S.; Whitton, J. L.; Kaminsky, M.

    Studies were conducted to explore if the surface exfoliation of Inconel 625, typical for 100 keV 4He + irradiations can be reduced by pre-irradiating the surfaces with helium ions sequentially over the energy range 20 to 50 keV. Polished, polycrystalline Inconel 625 samples were irradiated at 298K and 573K with 4He + at six different energies in the range from 20 to 50 keV in an order of decreasing energies. For each energy the dose was 0.13 C/cm 2, resulting in a total dose of 0.89 C/cm 2. Subsequently, these samples were implanted with 100 keV 4He + to a dose of 1.0 C/cm 2 or 2.0 C/cm 2. The results reveal that the low energy 4He + implants prior to the 100 keV 4He + implant reduce significantly the erosion yield typical for 100-keV 4He + irradiations alone. For 573K these reduced yields are still about one order of magnitude greater than physical sputtering yields.

  16. Ionization at the Noble Gases Ion-Atom Collisions in the 1-7 KeV Energy Range

    NASA Astrophysics Data System (ADS)

    Kikiani, Boris; Chitaladze, Marika; Japaridze, Josif; Kavlashvili, Nana

    2002-10-01

    The absolute total cross sections for production of free electrons, all positive show target gas ions and partial cross sections for production of double charged slow target gas ions at these collisions have been measured. The measurements were carried out by improved transfers electric field ("condenser") and magnetic mass-analyzer methods[1]. It was shown that in the investigated energy range practically there are now slow ions with charged state more than two. Control experiments have been shown that process of electron's liberation from fast particles ("stripping" process) is unlikely in the investigated energy range. Therefore, one can to suppose that total cross sections for productions of free electrons are equal to the total cross sections of ionization of the target gas atoms. For symmetrical pairs of colliding particles (He+ _ He, Ne+ _ Ne , etc) and for pairs He+ _ Ne, Ar+ _ Kr and Kr+ _ Xe values of partial cross-sections are negligible. In the cases of He+ _ Kr and He+ _ Xe pairs value of these partial cross sections increases with colliding energy and reaches about three percent at the energy 4kev. However, in the cases of He+ _ Ar, Na+ _ Ar, Kr, Xe the values of relative portion of the double charged ions in the total amount of slow positive ions are significant (for example in He+ _ Ar collision at the energy of 4kev this portion is about 20-25 percent). Analyzes of the correlation diagrams of the diabetics terms of colliding particles system (MS) [2] show that the electron capture processes are accompanying by simultaneous excitation of auto- ionization states of target gas ions. The decay of these states are responsible for realize of double ionization process of the target gas atoms. 1. B. Kikiani, R.Lomsadze, N. Mosulishvili, Proceedings of Tbilisi State University, Physics, 34, 114, 1999; 2 M. Barat, W.Lichten, Phys. Rev, A6, 211, 1972.

  17. Double ionization of helium by 2-keV electrons in equal- and unequal-energy configurations

    NASA Astrophysics Data System (ADS)

    Ambrosio, M. J.; Mitnik, D. M.; Dorn, A.; Ancarani, L. U.; Gasaneo, G.

    2016-03-01

    We present theoretical and experimental fully differential cross sections, in coplanar scattering geometry, for the double ionization of helium by electron impacting at 2 keV. The observed structures for both equal and unequal sharing of the excess energy are analyzed. Although the incident energy could, in principle, be regarded as high enough for the applicability of the first Born approximation in the projectile-target interaction, the experimental cross sections, measured with a COLTRIMS apparatus, show that further orders' effects can be appreciated. The theoretical cross sections are calculated with the generalized Sturmian functions method, which exactly solves the three-body problem that stems from a first-order projectile-target perturbative treatment.

  18. Attenuation coefficients of soils and some building materials of Bangladesh in the energy range 276-1332 keV.

    PubMed

    Alam, M N; Miah, M M; Chowdhury, M I; Kamal, M; Ghose, S; Rahman, R

    2001-06-01

    The linear and mass attenuation coefficients of different types of soil, sand, building materials and heavy beach mineral samples from the Chittagong and Cox's Bazar area of Bangladesh were measured using a high-resolution HPGe detector and the gamma-ray energies 276.1, 302.8, 356.0, 383.8, 661.6 and 1173.2 and 1332.5 keV emitted from point sources of 133Ba, 137Cs and 60Co, respectively. The linear attenuation coefficients show a linear relationship with the corresponding densities of the samples studied. The variations of the mass attenuation coefficient with gamma-ray energy were exponential in nature. The measured mass attenuation coefficient values were compared with measurements made in other countries for similar kinds of materials. The values are in good agreement with each other in most cases. PMID:11300413

  19. Cross sections for ionization of tetrahydrofuran by protons at energies between 300 and 3000 keV

    NASA Astrophysics Data System (ADS)

    Wang, Mingjie; Rudek, Benedikt; Bennett, Daniel; de Vera, Pablo; Bug, Marion; Buhr, Ticia; Baek, Woon Yong; Hilgers, Gerhard; Rabus, Hans

    2016-05-01

    Double-differential cross sections for ionization of tetrahydrofuran by protons with energies from 300 to 3000 keV were measured at the Physikalisch-Technische Bundesanstalt ion accelerator facility. The electrons emitted at angles between 15∘ and 150∘ relative to the ion-beam direction were detected with an electrostatic hemispherical electron spectrometer. Single-differential and total ionization cross sections have been derived by integration. The experimental results are compared to the semiempirical Hansen-Kocbach-Stolterfoht model as well as to the recently reported method based on the dielectric formalism. The comparison to the latter showed good agreement with experimental data in a broad range of emission angles and energies of secondary electrons. The scaling property of ionization cross sections for tetrahydrofuran was also investigated. Compared to molecules of different size, the ionization cross sections of tetrahydrofuran were found to scale with the number of valence electrons at large impact parameters.

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

    SciTech Connect

    Kruschwitz, Craig; Wu, M.; Rochau, G. A.

    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.

  1. 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

  2. Measurement of Lα and Lβ1,3,4 fluorescence cross sections of La, Ce, Pr and Nd induced by photons of energies between 7.01 keV and 8.75 keV

    NASA Astrophysics Data System (ADS)

    Reyes-Herrera, J.; Miranda, J.

    2016-06-01

    This study presents measurement results of x-ray production cross sections of Lα and Lβ1,3,4 emitted by four lanthanoid elements (La, Ce, Pr and Nd), after irradiation with Kα and Kβ X rays of the elements Co, Ni, Cu, and Zn (covering energies between 7.01 keV and 8.75 keV). Primary x-rays were induced in turn by the irradiation of thick targets of these elements with a beam of x-rays produced by a tube with an Rh anode, operating at 50 kV and 850 μA. The experimental results are compared with theoretical cross sections predicted using known tabulations of photoelectric cross sections. Dirac-Hartree-Slater (DHS) atomic parameters were used for these calculations. An acceptable match between experiment and both sets of tabulated data is found.

  3. Energy response of GR-200A thermoluminescence dosemeters to 60Co and to monoenergetic synchrotron radiation in the energy range 28-40 keV.

    PubMed

    Emiro, F; Di Lillo, F; Mettivier, G; Fedon, C; Longo, R; Tromba, G; Russo, P

    2016-01-01

    The response of LiF:Mg,Cu,P thermoluminescence dosemeters (type GR-200A) to monoenergetic radiation of energy 28, 35, 38 and 40 keV was evaluated with respect to irradiation with a calibrated (60)Co gamma-ray source. High-precision measurements of the relative air kerma response performed at the SYRMEP beamline of the ELETTRA synchrotron radiation facility (Trieste, Italy) showed a significant deviation of the average response to low-energy X-rays from that to (60)Co, with an over-response from 6 % (at 28 keV) to 22 % (at 40 keV). These data are not consistent with literature data for these dosemeters, where model predictions gave deviation from unity of the relative air kerma response of about 10 %. The authors conclude for the need of additional determinations of the low-energy relative response of GR-200A dosemeters, covering a wider range of monoenergetic energies sampled at a fine energy step, as planned in future experiments by their group at the ELETTRA facility. PMID:25737582

  4. Spectral Efficiency and Resolution of Si(Li)-Detectors for Photon Energies between 0.3 keV and 5 keV

    NASA Astrophysics Data System (ADS)

    Riehle, F.; Tegeler, E.; Wende, B.

    1986-01-01

    The spectral efficiencies of energy dispersive Si(Li) photon counters have been measured using the storage ring BESSY as a radiometric standard source of extremely low photon flux of the order of 1 photon/(s eV). The detectors were irradiated with white synchrotron radia-tion when the storage ring was operated with only about 5 electrons stored. For energy calibration and measurement of the energy resolution X-ray emission lines excited by a 55-Fe source were used. Towards lower photon energies the efficiency is drastically decreased by the building-up of an ice-layer on the permanently cooled detector. By this surface contamination also the energy resolution of the detector is affected. The performance of detector can be recovered by a warming-up procedure.

  5. High-resolution integrated germanium Compton polarimeter for the γ-ray energy range 80 keV-1 MeV

    NASA Astrophysics Data System (ADS)

    Sareen, R. A.; Urban, W.; Barnett, A. R.; Varley, B. J.

    1995-06-01

    Parameters which govern the choice of a detection system to measure the linear polarization of γ rays at low energies are discussed. An integrated polarimeter is described which is constructed from a single crystal of germanium. It is a compact planar device with the sectors defined electrically, and which gives an energy resolution in the add-back mode of 1 keV at 300 keV. Its performance is demonstrated in a series of calibration measurements using both unpolarized radiation from radioactive sources and polarized γ rays from the 168Er(α,2n)170Yb reaction at Eα=25 MeV. Polarization measurements at energies as low as 84 keV have been achieved, where the sensitivity was 0.32±0.09. The sensitivity, efficiency, and energy resolution are reported. Our results indicate that energy resolution should be included in the definition of the figure of merit and we relate the new definition to earlier work. The comparisons show the advantages of the present design in the energy range below 300 keV and its competitiveness up to 1500 keV.

  6. 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.

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

    PubMed

    Singh, Amrit; Dhaliwal, A S

    2016-09-01

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

  8. Determination of energy loss of 1200 keV deuterons along axial and planar channels of Si

    NASA Astrophysics Data System (ADS)

    Shafiei, S.; Lamehi-Rachti, M.

    2015-02-01

    In this paper, the energy loss of 1200 keV deuterons along the <1 0 0> and <1 1 0> axes as well as the {1 0 0} and {1 1 0} planes of Si were determined by the simulation of the channeling Rutherford backscattering spectra. The simulation was done by taking two considerations into account: (i) a minimum random component of the beam which enters the sample because of the scattering ions from the surface, (ii) the dechanneling starts at greater penetration depths, xDech. Moreover, it was assumed that the dechanneling follows a Gompertz type sigmoidal function with two parameters k and xc which present the dechanneling rate and range, respectively. The best simulation parameters, penetration depth at which the dechanneling starts, energy loss and dechanneling rate and range, were chosen by using the Levenberg-Marquardt algorithm. The experimental results are well reproduced by this simulation. The ratio of channeling energy loss to the random is changed from 0.63 ± 0.02 along the <1 1 0> axial channel to the 0.91 ± 0.02 along the {1 0 0} planar direction. The differences in the energy loss and the dechanneling process along the axial and planar channels are attributed to the potential barrier and the fractional area of each channel blocked by atoms. The ratio of channeling to random energy loss of deuterons along the <1 0 0> axial direction is in agreement with another reference.

  9. First wave of cultivators spread to Cyprus at least 10,600 y ago.

    PubMed

    Vigne, Jean-Denis; Briois, François; Zazzo, Antoine; Willcox, George; Cucchi, Thomas; Thiébault, Stéphanie; Carrère, Isabelle; Franel, Yodrik; Touquet, Régis; Martin, Chloé; Moreau, Christophe; Comby, Clothilde; Guilaine, Jean

    2012-05-29

    Early Neolithic sedentary villagers started cultivating wild cereals in the Near East 11,500 y ago [Pre-Pottery Neolithic A (PPNA)]. Recent discoveries indicated that Cyprus was frequented by Late PPNA people, but the earliest evidence until now for both the use of cereals and Neolithic villages on the island dates to 10,400 y ago. Here we present the recent archaeological excavation at Klimonas, which demonstrates that established villagers were living on Cyprus between 11,100 and 10,600 y ago. Villagers had stone artifacts and buildings (including a remarkable 10-m diameter communal building) that were similar to those found on Late PPNA sites on the mainland. Cereals were introduced from the Levant, and meat was obtained by hunting the only ungulate living on the island, a small indigenous Cypriot wild boar. Cats and small domestic dogs were brought from the mainland. This colonization suggests well-developed maritime capabilities by the PPNA period, but also that migration from the mainland may have occurred shortly after the beginning of agriculture. PMID:22566638

  10. 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.

    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.

  11. 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.

  12. Experimental study of interactions of highly charged ions with atoms at keV energies

    SciTech Connect

    Kostroun, V.O.

    1992-07-05

    This Progress Report describes the experimental work carried out, and the work in progress, at the Cornell EBIS Laboratory during the period 7/1/1991 to 6/30/1992. During this period, a number of experiments were carried out. The absolute values of the total, one, two and three electron transfer cross sections for highly charged argon ions (8{le}q{le}16) colliding with argon at 2.3 qkev laboratory energy were measured. The distribution of recoil ions and molecular fragments formed in highly charged ion atom and molecule collisions was measured in order to help the interpretation of electron spectra in the 40--320 eV energy range emitted in Ar{sup q+}+Ar(8{le}q{le}16) collisions at 2.3 qkeV that were measured in our laboratory. The interpretation of the electron spectra is still under way. A new collision chamber was built which contains an ion decelerating lens system and a high resolution monochromator-analyzer combination. Ions extracted from the Cornell Electron Beam Ion Source were successfully decelerated from 2.3 qkeV down to 30 qeV Preliminary 0{degree} translational energy spectra for Ar{sup l2+} on Ar at a collision energy of 38.6 qeV show a 0.56 qeV resolution. Work is in progress to extend measurements of cross sections and recoil ion charge state distributions down to collision energies in the 10 eV/amu range.

  13. Parameter estimation of magnetospheric particle distributions in the energy range 20 to 500 keV

    NASA Astrophysics Data System (ADS)

    Torkar, K. M.

    1982-04-01

    A computer program which analyzes the energy spectra of energetic magnetospheric particles is described. The instrument characteristics and experimental design of the geostationary satellite GEOS-2 which provided the raw data are indicated. The program is designed to run on a UNIVAC 1100/81 computer and requires a plotter and a terminal with basic display enhancement features. Three dimensional charts showing the spectral distribution of energetic electrons are included.

  14. 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

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

    SciTech Connect

    Windt, David L.

    2015-04-15

    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 μm × 800 μm 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.

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

    NASA Astrophysics Data System (ADS)

    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 μm × 800 μm 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.

  17. 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 |δ ( 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.

  18. 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

  19. Mass attenuation coefficients of Martian meteorites and Earth composition in the energy range 1 keV-100 GeV

    NASA Astrophysics Data System (ADS)

    Ün, M.; Han, E. Narmanli; Ün, A.

    2016-04-01

    Mass attenuation coefficients for 24 Martian meteorites have been determined in the energy range from 1 keV to 100 GeV. The values of mass attenuation coefficients (µ/ρ) of the samples were calculated the WINXCOM program. The obtained results for Martian meteorites have been compared with the results for Earth composition and similarities or differences also evaluated.

  20. 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).

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

    SciTech Connect

    Seely, J. F. Feldman, U.; Glover, J. L.; Hudson, L. T.; Ralchenko, Y.; Henins, Albert; Pereira, N.; Di Stefano, C. A.; Kuranz, C. C.; Drake, R. P.; Chen, Hui; Williams, G. J.; Park, J.

    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 μm 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.

  2. High Voltage-Cylinder Sector Analyzer 300/15: a cylindrical sector analyzer for electron kinetic energies up to 15 keV.

    PubMed

    Rubio-Zuazo, J; Escher, M; Merkel, M; Castro, G R

    2010-04-01

    We have developed an energy analyzer, High Voltage-Cylinder Sector Analyzer 300/15, for electron kinetic energies up to 15 keV. It is especially suited for hard x-ray photoelectron spectroscopy, but also for ultraviolet and soft x-ray photoelectron spectroscopy (ultraviolet photoemission spectroscopy, x-ray photoemission spectroscopy), Auger electron spectroscopy, and reflection high energy electron spectroscopy. The analyzer is based on a cylinder sector with 90 degrees deflection, 300 mm slit-to-slit distance, and a four-element pre-retarding lens system with 50 mm sample-to-lens distance. The result is a very compact design of the analyzer that is easily integrated into a multipurpose experiment with different techniques. A low noise/low drift electronics is capable of continuous energy scans from 0 to 15 keV using nonlinear lens curves. The first analyzer is allocated at the Spanish CRG SpLine beamline at the ESRF at an end station where simultaneous surface x-ray diffraction is possible. The analyzer is operated routinely since 2006 up to 15 keV electron kinetic energy, expanding the achievable electron kinetic energy range compared to other commercial analyzers. In this work we present a detailed description of the developed electron analyzer. The analyzer capabilities, in terms of energy resolution and transmission, are shown by using an electron gun, an ultraviolet-discharge lamp, and hard x-ray synchrotron radiation as excitation sources. PMID:20441333

  3. Comparison of Martian meteorites with earth composition: Study of effective atomic numbers in the energy range 1 keV-100 GeV

    NASA Astrophysics Data System (ADS)

    Ün, Adem; Han, Ibrahim; Ün, Mümine

    2016-04-01

    Effective atomic (Zeff) and electron numbers (Neff) for 24 Martian meteorites have been determined in the energy range from 1 keV to 100 GeV and also for sixteen significant energies of commonly used radioactive sources. The values of Zeff and Neff for all sample were obtained from the DirectZeff program. The obtained results for Martian meteorites have been compared with the results for Earth composition and similarities or differences also evaluated.

  4. Medium-energy ion irradiation of Si and Ge wafers: studies of surface nanopatterning and signature of recrystallization in 100 keV Kr+ bombarded a-Si

    NASA Astrophysics Data System (ADS)

    Kumar, Pravin

    2016-03-01

    We report new and exciting experimental results on ion-induced nanopatterning of a-Si and a-Ge surfaces. The crystalline Si (100) and Ge (100) wafers were amorphized and an a/c interface was developed by pre-irradiation with a 50 keV Ar+ beam at normal incidence with an ion fluence of 5.0 × 1015 ions cm-2. These amorphized surfaces were post-irradiated with Ar+ and Kr+ beams at an angle of 60°. The post irradiation was done with ion fluences of 1.0 × 1017 ions cm-2. For each beam, two energies (50 and 200 keV for Ar+, 100 and 250 keV for Kr+) were chosen to ensure ion stopping in both sides of the a/c interface. Regular nanopatterning (in the form of ripples) is observed on the Ge surface only with the post irradiation of the Kr+ beam. The Si surface showed regular nanopatterning with the irradiation of both beams with two energies. For the ion beams crossing the a/c interface, ripples of higher amplitude and longer wavelength were formed. Further, the irradiation with a heavy beam yielded surface ripples of relatively larger amplitudes. The Raman measurements confirm amorphization of the pre-irradiated surfaces. Surprisingly, the post-irradiated Si surface with the 100 keV Kr+ beam showed evidence of recrystallization. In the paper we discuss the physics at the interface and explain the experimental findings.

  5. Interferometric phase-contrast X-ray CT imaging of VX2 rabbit cancer at 35keV X-ray energy

    SciTech Connect

    Takeda, Tohoru; Wu Jin; Tsuchiya, Yoshinori; Lwin, Thet-Thet; Itai, Yuji; Yoneyama, Akio; Hyodo, Kazuyuki

    2004-05-12

    Imaging of large objects at 17.7-keV low x-ray energy causes huge x-ray exposure to the objects even using interferometric phase-contrast x-ray CT (PCCT). Thus, we tried to obtain PCCT images at high x-ray energy of 35keV and examined the image quality using a formalin-fixed VX2 rabbit cancer specimen with 15-mm in diameter. The PCCT system consisted of an asymmetrically cut silicon (220) crystal, a monolithic x-ray interferometer, a phase-shifter, an object cell and an x-ray CCD camera. The PCCT at 35 keV clearly visualized various inner structures of VX2 rabbit cancer such as necrosis, cancer, the surrounding tumor vessels, and normal liver tissue. Besides, image-contrast was not degraded significantly. These results suggest that the PCCT at 35 KeV is sufficient to clearly depict the histopathological morphology of VX2 rabbit cancer specimen.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. Possible low energy (E less than keV) nonthermal X-ray events. [analysis of proportional counter detector data from OGO-5

    NASA Technical Reports Server (NTRS)

    Kahler, S. W.

    1973-01-01

    A search of the 3- to 30-keV data from the NRL proportional counter detector on the Orbiting Geophysical Observatory-5 (OGO-5) satellite has yielded several events which may be nearly completely nonthermal in the e greater than 3 and less than 10 keV range. In each case an impulsive hard X-ray burst accompained by an impulsive microwave burst was associated with a low energy X-ray burst whose profile was a simple rise and fall. The lack of a two component nature in the low energy range argues that the low energy X-ray flux is due to a single physical mechanism, in this case nonthermal bremsstrahlung from accelerated electrons. However, the spectra and time profiles are quite consistent with a thermal interpretation. Polarization measurements are probably necessary to resolve the physical origin of such bursts.

  8. Effective atomic numbers and electron densities of bacteriorhodopsin and its comprising amino acids in the energy range 1 keV-100 GeV

    NASA Astrophysics Data System (ADS)

    Ahmadi, Morteza; Lunscher, Nolan; Yeow, John T. W.

    2013-04-01

    Recently, there has been an interest in fabrication of X-ray sensors based on bacteriorhodopsin, a proton pump protein in cell membrane of Halobacterium salinarium. Therefore, a better understanding of interaction of X-ray photons with bacteriorhodopsin is required. We use WinXCom program to calculate the mass attenuation coefficient of bacteriorhodopsin and its comprising amino acids for photon energies from 1 keV to 100 GeV. These amino acids include alanine, arginine, asparagine, aspartic acid, glutamine, glutamic acid, glycine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine, valine, Asx1, Asx2, Glx1 and Glx2. We then use that data to calculate effective atomic number and electron densities for the same range of energy. We also emphasize on two ranges of energies (10-200 keV and 1-20 MeV) in which X-ray imaging and radiotherapy machines work.

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

    SciTech Connect

    Jimenez-Rey, D.; Rodriguez-Barquero, L.

    2010-10-15

    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{sub 2}S{sub 4}:Eu (also known as TG-Green), when irradiated by H{sup +} 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.

  10. 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 (Zeff RW) 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.

  11. Measurements of the X-ray linear attenuation coefficient for low atomic number materials at energies 32-66 and 140 keV

    NASA Astrophysics Data System (ADS)

    Midgley, S. M.

    2005-03-01

    The X-ray linear attenuation coefficient was measured for materials containing elements hydrogen to calcium. Characteristic X-rays with energies 32- 66 keV were produced by X-ray fluorescence using a secondary target system, and 140 keV gamma rays were obtained from an unsealed 99 mTc source. The photon beams were highly collimated and recorded using energy dispersive detection. A high-purity germanium detector was utilised to distinguish between measurements with K α and K β characteristic X-rays, and the gamma ray measurements used a sodium iodide detector. Samples were selected on the basis of having known composition and mass densities were measured using a pycnometer. The samples comprised six plastics, seven crystalline materials, three tissue substitute materials, three liquids and six salt solutions. Our results have an uncertainty of less than 2% and are a few percent lower than values predicted by the tabulations.

  12. Measurement of attenuation coefficients for bone, muscle, fat and water at 140, 364 and 662 keV γ-ray energies

    NASA Astrophysics Data System (ADS)

    Akar, A.; Baltaş, H.; Çevik, U.; Korkmaz, F.; Okumuşoğlu, N. T.

    2006-11-01

    The half-value thicknesses, linear and mass attenuation coefficients of biological samples such as bone, muscle, fat and water have been measured at 140, 364 and 662 keV γ-ray energies by using the ATOMLABTM-930 medical spectrometer. The γ-rays were obtained from 99mTc, 131I and 137Cs γ-ray point sources. Also theoretical calculations have been performed in order to obtain the half-value thicknesses and, mass and linear attenuation coefficients at photon energies 0.001 keV 20 MeV for bone, muscle and water samples. The calculated value and the experimental results of this work and the other results in literature are found to be in good agreement.

  13. 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.

  14. First INTEGRAL Observations of V404 Cygni during the 2015 Outburst: Spectral Behavior in the 20-650 keV Energy Range

    NASA Astrophysics Data System (ADS)

    Roques, Jean-Pierre; Jourdain, Elisabeth; Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ˜200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT0 ˜ 7 keV) is introduced. Above this first component, a clear excess extending up to 400-600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10-4 ph cm-2 s-1 (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum. Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic, and Poland with the participation of Russia and USA.

  15. First INTEGRAL Observations of V404 Cygni during the 2015 Outburst: Spectral Behavior in the 20–650 keV Energy Range

    NASA Astrophysics Data System (ADS)

    Roques, Jean-Pierre; Jourdain, Elisabeth; Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ∼200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT0 ∼ 7 keV) is introduced. Above this first component, a clear excess extending up to 400–600 keV leads us to investigate a scenario where an additional (cutoff) power law could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10‑4 ph cm‑2 s‑1 (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum. Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Spain, and Switzerland), Czech Republic, and Poland with the participation of Russia and USA.

  16. Reference neutron fields of the KIGAM for the neutron energy range between 144 keV and 2.5 MeV

    NASA Astrophysics Data System (ADS)

    Kim, G. D.; Woo, H. J.; Choi, H. W.; Park, J. W.; Trinh, T. A.

    2012-08-01

    The Korea Institute of Geoscience and Mineral Resources (KIGAM) is constructing a reference neutron field facility as a national project. Neutron fields consist of mono-energetic sources of 144 keV, 250 keV, 565 keV, and 2.5 MeV have a fluence range from 102 neutrons/cm2/sec to 103 neutrons/cm2/sec. The systems for the reference neutron fields, such as a duo-plasmatron ion source, a 4-MHz beam bunching system, a neutron chamber, an irradiation room, a neutron time-of-flight (n-TOF) system, a long-counter, and a sample moving system, were designed and fabricated. The neutron energies of the reference neutron fields and their spreads were observed by using the n-TOF system. The neutron fluence was measured by using a long-counter for energies below 1 MeV and a proton-recoil counter for 2.5 MeV. The long-counter efficiency was calibrated by the Japan Atomic Energy Agency (JAEA) which had a traceability of mono-energetic neutron sources to both Japanese and international standards. The efficiency of the proton-recoil counter was obtained by using a calculation with detailed construction information.

  17. Measurement of lineal-energy distributions for neutrons of 8 keV to 65 MeV by using a tissue-equivalent proportional counter.

    PubMed

    Nunomiya, T; Kim, E; Kurosaw, T; Taniguchi, S; Nakamura, T; Nakane, Y; Sakamoto, Y; Tanaka, S

    2002-01-01

    The lineal-energy spectra for monoenergetic and quasi-monoenergetic neutrons of 8 keV to 65 MeV were obtained using a tissue-equivalent proportional counter (TEPC). The frequency-mean lineal energy, the dose-average lineal energy and mean quality factor were estimated from the measured data. The neutron absorbed doses obtained with this TEPC were compared with the kerma coefticient for A-150 plastic defined by ICRP 26 and the mean quality factors were compared with the data of ICRP 74. respectively. These comparisons indicated good agreement between them. PMID:12212902

  18. 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.

  19. 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 keV-60 keV.

    SciTech Connect

    de Jonge, M. D.; Tran, C. Q.; Chantler, C. T.; Barnea, Z.; Dhal, B. P.; Paterson, D.; Kanter, E. P.; Southworth, S. H.; Young, L.; Beno, M. A.; Linton, J. A.; Jennings, G.; Univ. of Melbourne; Australian Synchrotron Project

    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 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.

  20. Absolute calibration of Kodak Biomax-MS film response to x rays in the 1.5- to 8-keV energy range

    NASA Astrophysics Data System (ADS)

    Marshall, F. J.; Knauer, J. P.; Anderson, D.; Schmitt, B. L.

    2006-10-01

    The absolute response of Kodak Biomax-MS film to x rays in the range from 1.5- to 8-keV has been measured using a laboratory electron-beam generated x-ray source. The measurements were taken at specific line energies by using Bragg diffraction to produce monochromatic beams of x rays. Multiple exposures were taken on Biomax MS film up to levels exceeding optical densities of 2 as measured by a microdensitometer. The absolute beam intensity for each exposure was measured with a Si (Li) detector. Additional response measurements were taken with Kodak direct exposure film (DEF) so as to compare the results of this technique to previously published calibrations. The Biomax-MS results have been fitted to a semiempirical mathematical model (Knauer et al., these proceedings). Users of the model can infer absolute fluences from observed exposure levels at either interpolated or extrapolated energies. To summarize the results: Biomax MS has comparable sensitivity to DEF film below 3keV but has reduced sensitivity above 3keV (˜50%). The lower exposure results from thinner emulsion layers, designed for use with phosphor screens. The ease with which Biomax-MS can be used in place of DEF (same format film, same developing process, and comparable sensitivity) makes it a good replacement.

  1. Absolute calibration of Kodak Biomax-MS film response to x rays in the 1.5- to 8-keV energy range

    SciTech Connect

    Marshall, F. J.; Knauer, J. P.; Anderson, D.; Schmitt, B. L

    2006-10-15

    The absolute response of Kodak Biomax-MS film to x rays in the range from 1.5- to 8-keV has been measured using a laboratory electron-beam generated x-ray source. The measurements were taken at specific line energies by using Bragg diffraction to produce monochromatic beams of x rays. Multiple exposures were taken on Biomax MS film up to levels exceeding optical densities of 2 as measured by a microdensitometer. The absolute beam intensity for each exposure was measured with a Si(Li) detector. Additional response measurements were taken with Kodak direct exposure film (DEF) so as to compare the results of this technique to previously published calibrations. The Biomax-MS results have been fitted to a semiempirical mathematical model (Knauer et al., these proceedings). Users of the model can infer absolute fluences from observed exposure levels at either interpolated or extrapolated energies. To summarize the results: Biomax MS has comparable sensitivity to DEF film below 3 keV but has reduced sensitivity above 3 keV ({approx}50%). The lower exposure results from thinner emulsion layers, designed for use with phosphor screens. The ease with which Biomax-MS can be used in place of DEF (same format film, same developing process, and comparable sensitivity) makes it a good replacement.

  2. A low background-rate detector for ions in the 5 to 50 keV energy range to be used for radioisotope dating with a small cyclotron

    SciTech Connect

    Friedman, P.G.

    1986-11-25

    Accelerator mass spectrometry in tandem Van de Graaff accelerators has proven successful for radioisotope dating small samples. We are developing a 20 cm diameter 30 to 40 keV cyclotron dedicated to high-sensitivity radioisotope dating, initially for /sup 14/C. At this energy, range and dE/dx methods of particle identification are impossible. Thus arises the difficult problem of reliably detecting 30 to 40 keV /sup 14/C at 10/sup -2/ counts/sec in the high background environment of the cyclotron, where lower energy ions, electrons, and photons bombard the detector at much higher rates. We have developed and tested an inexpensive, generally useful ion detector that allows dark-count rates below 10/sup -4/ counts/sec and excellent background suppression. With the cyclotron tuned near the /sup 13/CH background peak, to the frequency for /sup 14/C, the detector suppresses the background to 6 x 10/sup -4/ counts/sec. For each /sup 14/C ion the detectors grazing-incidence Al/sub 2/O/sub 3/ conversion dynode emits about 20 secondary electrons, which are independently multiplied in separate pores of a microchannel plate. The output signal is proportional to the number of secondary electrons, allowing pulse-height discrimination of background. We have successfully tested the detector with positive /sup 12/C, /sup 23/Na, /sup 39/K, /sup 41/K, /sup 85/Rb, /sup 87/Rb, and /sup 133/Cs at 5 to 40 keV, and with 36 keV negative /sup 12/C and /sup 13/CH. It should detect ions and neutrals of all species, at energies above 5 keV, with good efficiency and excellent background discrimination. Counting efficiency and background discrimination improve with higher ion energy. The detector can be operated at least up to 2 x 10/sup -7/ Torr and be repeatedly exposed to air. The maximum rate is 10/sup 6.4/ ions/sec in pulse counting mode and 10/sup 9.7/ ions/sec in current integrating mode.

  3. The association of fractional CO2 laser 10.600nm and photodynamic therapy in the treatment of onychomycosis*

    PubMed Central

    de Oliveira, Guilherme Bueno; Antonio, João Roberto; Antonio, Carlos Roberto; Tomé, Fernanda Alves

    2015-01-01

    BACKGROUND Onychomycosis is a fungal infection of the nails caused in most cases by dermatophytes Trichophyton rubrum and Trichophyton mentagrophytes. Despite numerous available antifungal drugs for therapy of this infection, the cure rate is low, with high rates of relapse after treatment and side effects. OBJECTIVES To present a new option for the treatment of onychomycosis, in search of a more effective and rapid method than conventional ones. METHODS Patients underwent two sessions of CO2 fractional laser 10.600nm associated with photodynamic therapy. Mycological and digital photography were performed before and after the treatment. RESULTS McNemar test with continuity correction and degrees of freedom = 1: for clinical cure rate, 13.06, with p=0.00005; for mycological cure, 17.05, with p=0.00005; 72% felt fully satisfied with the procedure. CONCLUSIONS The use of fractional CO2 laser 10.600nm associated with photodynamic therapy can be effective in the treatment of onychomycosis, decreasing the risk of systemic lesions that may be triggered with prolonged use of oral antifungals. PMID:26375214

  4. 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 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

  5. 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.

    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 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients.

  6. Moiré deflectometry using the Talbot-Lau interferometer as refraction diagnostic for high energy density plasmas at energies below 10 keV.

    PubMed

    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 μm size we obtained accurate simultaneous measurements of refraction and attenuation for both sharp and mild electron density gradients. PMID:25085141

  7. Optimization of the cell in the ion-optical system of a powerful source of protons with energy 15 keV

    NASA Astrophysics Data System (ADS)

    Sorokin, A. V.; Davydenko, V. I.; Deichuli, P. P.; Ivanov, A. A.

    2016-07-01

    We have described the results of numerical investigations of different versions of a three-electrode elementary slit cell for the formation a hydrogen ion beam with a relatively low energy and a high emission current density. The version of the cell chosen from the results of these investigations makes it possible to obtain a hydrogen atom beam with an energy of 15 keV, an ion current density of ~500 mA/cm2, and an angular divergence of 24 mrad.

  8. Experimental study of interactions of highly charged ions with atoms at keV energies. Progress report, February 16, 1993--April 15, 1994

    SciTech Connect

    Kostroun, V.O.

    1994-04-27

    Experimental study of low energy, highly charged ions with other atomic species requires an advanced ion source such as an electron beam ion source, EBIS or an electron cyclotron ion source, ECRIS. Five years ago we finished the design and construction of the Cornell superconducting solenoid, cryogenic EBIS (CEBIS). Since then, this source has been in continuous operation in a program whose main purpose is the experimental study of interactions of highly charged ions with atoms at keV energies. This progress report for the period February 16, 1993 to April 15, 1994 describes the work accomplished during this time in the form of short abstracts.

  9. The low energy particle detector sled (~30 keV-3.2 MeV) and its performance on the phobos mission to mars and its moons

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S.; Afonin, V. V.; Gringauz, K. I.; Keppler, E.; Kirsch, E.; Richter, A.; Witte, M.; O'Sullivan, D.; Thompson, A.; Somogyi, A. J.; Szabo, L.; Varga, A.

    1990-05-01

    A low energy particle detector system (SLED) is described which was designed to measure the flux densities of electrons and ions in the energy range from ~30 keV to a few MeV in (a) the varying solar aspect angles and temperatures pertaining during the Cruise Phase of the Phobos Mission and (b) in the low temperature environment (reaching -25° C) pertaining during Mars Encounter. Representative data illustrating the excellent functioning of SLED during both phases of the mission are presented.

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

    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. Reduction in the intensity of solar X-ray emission in the 2- to 15-keV photon energy range and heating of the solar corona

    SciTech Connect

    Mirzoeva, I. K.

    2013-04-15

    The time profiles of the energy spectra of low-intensity flares and the structure of the thermal background of the soft X-ray component of solar corona emission over the period of January-February, 2003, are investigated using the data of the RHESSI project. A reduction in the intensity of X-ray emission of the solar flares and the corona thermal background in the 2- to 15-keV photon energy range is revealed. The RHESSI data are compared with the data from the Interball-Geotail project. A new mechanism of solar corona heating is proposed on the basis of the results obtained.

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

    NASA Astrophysics Data System (ADS)

    Singh, Amrit; Dhaliwal, A. S.

    2015-08-01

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

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

    SciTech Connect

    Singh, Amrit; Dhaliwal, A. S.

    2015-08-28

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

  14. 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 π/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.

  15. 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.

  16. 6 x 6-cm fully depleted pn-junction CCD for high-resolution spectroscopy in the 0.1- to 15-keV photon energy range

    NASA Astrophysics Data System (ADS)

    von Zanthier, Christoph; Holl, Peter; Kemmer, Josef; Lechner, Peter; Maier, B.; Soltau, Heike; Stoetter, R.; Braeuninger, Heinrich W.; Dennerl, Konrad; Haberl, Frank; Hartmann, R.; Hartner, Gisela D.; Hippmann, H.; Kastelic, E.; Kink, W.; Krause, N.; Meidinger, Norbert; Metzner, G.; Pfeffermann, Elmar; Popp, M.; Reppin, Claus; Stoetter, Diana; Strueder, Lothar; Truemper, Joachim; Weber, U.; Carathanassis, D.; Engelhard, S.; Gebhart, Th.; Hauff, D.; Lutz, G.; Richter, R. H.; Seitz, H.; Solc, P.; Bihler, Edgar; Boettcher, H.; Kendziorra, Eckhard; Kraemer, J.; Pflueger, Bernhard; Staubert, Ruediger

    1998-04-01

    The concept and performance of the fully depleted pn- junction CCD system, developed for the European XMM- and the German ABRIXAS-satellite missions for soft x-ray imaging and spectroscopy in the 0.1 keV to 15 keV photon range, is presented. The 58 mm X 60 mm large pn-CCD array uses pn- junctions for registers and for the backside instead of MOS registers. This concept naturally allows to fully deplete the detector volume to make it an efficient detector to photons with energies up to 15 keV. For high detection efficiency in the soft x-ray region down to 100 eV, an ultrathin pn-CCD backside deadlayer has been realized. Each pn-CCD-channel is equipped with an on-chip JFET amplifier which, in combination with the CAMEX-amplifier and multiplexing chip, facilitates parallel readout with a pixel read rate of 3 MHz and an electronic noise floor of ENC < e-. With the complete parallel readout, very fast pn-CCD readout modi can be implemented in the system which allow for high resolution photon spectroscopy of even the brightest x-ray sources in the sky.

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

    PubMed

    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. PMID:21239846

  18. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    NASA Astrophysics Data System (ADS)

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; Skoug, Ruth M.; Funsten, Herbert O.; Claudepierre, Seth G.; Fennell, Joseph F.; Turner, Drew L.; Denton, Mick H.; Spence, Harlan E.; Blake, J. Bernard; Baker, Daniel N.

    2016-01-01

    We present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are more common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of "slot filling" events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.

  19. Interferometric X-Ray Imaging of Breast Cancer Specimens at 51 keV X-Ray Energy

    NASA Astrophysics Data System (ADS)

    Takeda, Tohoru; Wu, Jin; Tsuchiya, Yoshinori; Yoneyama, Akio; Lwin, Thet Thet; Aiyoshi, Yuji; Zeniya, Tsutomu; Hyodo, Kazuyuki; Ueno, Ei

    2004-08-01

    The feasibility of the interferometric X-ray imaging technique is examined for revealing the features of breast cancer specimens. The interferometric X-ray imaging system consisted of an asymmetrically cut silicon crystal, a monolithic X-ray interferometer, a phase-shifter, an object cell, and an X-ray CCD camera. Ten 10-mm-thick formalin-fixed breast cancer specimens were imaged at 51 keV, and these images were compared with absorption-contrast X-ray images obtained at 18 keV monochromatic synchrotron X-ray. The interferometric X-ray images clearly depicted the essential features of the breast cancer such as microcalcification down to a size of 0.036 mm, spiculation, and detailed inner soft tissue structures closely matched with histopathological morphology, while the absorption-contrast X-ray images obtained using nearly the same X-ray dose only resolved microcalcification down to a size of 0.108 mm and spiculation. The interferometric X-ray imaging technique can be considered to be an innovative technique for the early and accurate diagnosis of breast cancer using an extremely low X-ray dose.

  20. The response of a radiation resistant ceramic scintillator (Al{sub 2}O{sub 3}:Cr) to low energy ions (0-60 keV)

    SciTech Connect

    Jimenez-Rey, D.; Zurro, B.; McCarthy, K. J.; Baciero, A.; Garcia, G.

    2008-10-15

    This work extends a previous study on ionoluminescence of a radiation-hard ceramic scintillator, Al{sub 2}O{sub 3}:Cr, to ions accelerated to keV energies [K. J. McCarthy et al., J. Nucl. Mater. 321, 78 (2003)]. It is motivated by the identification of this material as a promising candidate for use in the fast-ion-loss detector for ITER [for the range of thermal (low energy) and suprathermal ions]. In the paper we quantify and compare its ionoluminescence with that of some common luminescent materials (YAG:Ce and ruby) when irradiated by H{sup +} ions accelerated to {<=}60 keV using a purpose built laboratory setup. Next, studies are made on the ceramic to quantify its response as a function of incident ion mass, i.e., to He{sup +}. For this, the absolute luminosities of the material are estimated in terms of the number of photons emitted per incident ion as a function of energy. Moreover, the radiation hardness and postirradiation recovery of the ceramic are investigated. Finally, from the studies it can be concluded that the ceramic ruby is a good candidate for detecting low energy ions as long as its temporal response (approximately several milliseconds) is not a constraint for specific ion measurements.

  1. Use of a 10,600-nm CO2 Laser Mandibular Vestibular Extension in a Patient With a Chromosomal Abnormality.

    PubMed

    Levine, Robert; Vitruk, Peter

    2016-09-01

    Vestibuloplasty involves a series of surgical procedures designed to restore alveolar ridge height by lowering the muscles attached to the buccal, labial, and lingual aspects of the jaws. The technique is indicated in cases of insufficient vestibular depth that may result from atrophy of the alveolar ridge and/or high attachment of muscle or movable mucosa. This article focuses on a carbon dioxide (CO2) laser vestibular extension procedure performed in a patient with Klinefelter syndrome, which is caused by a chromosomal abnormality. The 10,600-nm CO2 laser is shown to offer several advantages over a conventional scalpel and other laser wavelengths for soft-tissue pre-prosthetic surgery, including vestibular extension. PMID:27608196

  2. Surface modifications of hydrogen storage alloy by heavy ion beams with keV to MeV irradiation energies

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Tokuhira, Shinnosuke; Uchida, Hirohisa; Ohshima, Takeshi

    2015-12-01

    This study deals with the effect of surface modifications induced from keV to MeV heavy ion beams on the initial reaction rate of a hydrogen storage alloy (AB5) in electrochemical process. The rare earth based alloys like this sample alloy are widely used as a negative electrode of Ni-MH (Nickel-Metal Hydride) battery. We aimed to improve the initial reaction rate of hydrogen absorption by effective induction of defects such as vacancies, dislocations, micro-cracks or by addition of atoms into the surface region of the metal alloys. Since defective layer near the surface can easily be oxidized, the conductive oxide layer is formed on the sample surface by O+ beams irradiation, and the conductive oxide layer might cause the improvement of initial reaction rate of hydriding. This paper demonstrates an effective surface treatment of heavy ion irradiation, which induces catalytic activities of rare earth oxides in the alloy surface.

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

    SciTech Connect

    Chen, L.; Shen, J.; Esaulov, V. A.; Valdes, J. E.; Vargas, P.

    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.

  4. 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

  5. Evaluation of Neutron Capture Cross Sections and Covariances on 99Tc and 129I in the keV Energy Region

    NASA Astrophysics Data System (ADS)

    Iwamoto, Nobuyuki

    2016-03-01

    Neutron capture cross sections and covariances on radioactive 99Tc and 129I have been required for developing environmental load-reducing technology. Their evaluation was performed by using nuclear reaction calculation code CCONE and Baysian code KALMAN with data assumed on the basis of measured data. The obtained total and capture cross sections are in good agreement with the measured data. The resulting uncertainties of capture cross section were 12-18% and 20-29% for 99Tc and 129I, respectively, in the keV energy region.

  6. A novel flat-response x-ray detector in the photon energy range of 0.1-4 keV

    NASA Astrophysics Data System (ADS)

    Li, Zhichao; Jiang, Xiaohua; Liu, Shenye; Huang, Tianxuan; Zheng, Jian; Yang, Jiamin; Li, Sanwei; Guo, Liang; Zhao, Xuefeng; Du, Huabin; Song, Tianming; Yi, Rongqing; Liu, Yonggang; Jiang, Shaoen; Ding, Yongkun

    2010-07-01

    A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1-4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1-4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiation temperatures inferred from the detector agree well with those from the diagnostic instrument Dante installed at the same azimuth angle from the hohlraum axis, demonstrating the feasibility of the detector.

  7. A novel flat-response x-ray detector in the photon energy range of 0.1-4 keV

    SciTech Connect

    Li Zhichao; Guo Liang; Jiang Xiaohua; Liu Shenye; Huang Tianxuan; Yang Jiamin; Li Sanwei; Zhao Xuefeng; Du Huabin; Song Tianming; Yi Rongqing; Liu Yonggang; Jiang Shaoen; Ding Yongkun; Zheng Jian

    2010-07-15

    A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1-4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1-4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiation temperatures inferred from the detector agree well with those from the diagnostic instrument Dante installed at the same azimuth angle from the hohlraum axis, demonstrating the feasibility of the detector.

  8. 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.

  9. A novel flat-response x-ray detector in the photon energy range of 0.1-4 keV.

    PubMed

    Li, Zhichao; Jiang, Xiaohua; Liu, Shenye; Huang, Tianxuan; Zheng, Jian; Yang, Jiamin; Li, Sanwei; Guo, Liang; Zhao, Xuefeng; Du, Huabin; Song, Tianming; Yi, Rongqing; Liu, Yonggang; Jiang, Shaoen; Ding, Yongkun

    2010-07-01

    A novel flat-response x-ray detector has been developed for the measurement of radiation flux from a hohlraum. In order to obtain a flat response in the photon energy range of 0.1-4 keV, it is found that both the cathode and the filter of the detector can be made of gold. A further improvement on the compound filter can then largely relax the requirement of the calibration x-ray beam. The calibration of the detector, which is carried out on Beijing Synchrotron Radiation Facility at Institute of High Energy Physics, shows that the detector has a desired flat response in the photon energy range of 0.1-4 keV, with a response flatness smaller than 13%. The detector has been successfully applied in the hohlraum experiment on Shenguang-III prototype laser facility. The radiation temperatures inferred from the detector agree well with those from the diagnostic instrument Dante installed at the same azimuth angle from the hohlraum axis, demonstrating the feasibility of the detector. PMID:20687719

  10. 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

    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.

  11. Wide-Band KB Optics for Spectro-Microscopy Imaging Applications in the 6-13 keV X-ray Energy Range

    SciTech Connect

    Ziegler, E.; De Panfilis, S.; Peverini, L.; Vaerenbergh, P. van; Rocca, F.

    2007-01-19

    We present a Kirkpatrick-Baez optics (KB) system specially optimized to operate in the 6-13 keV X-ray range, where valuable characteristic lines are present. The mirrors are coated with aperiodic laterally graded (Ru/B4C)35 multilayers to define a 15% energy bandpass and to gain flux as compared to total reflection mirrors. For any X-ray energy selected the shape of each mirror can be optimized with a dynamical bending system so as to concentrate the X-ray beam into a micrometer-size spot. Once the KB mirrors are aligned at the X-ray energy corresponding to the barycenter of the XAS spectrum to be performed they remain in a steady state during the micro-XAS scans to minimize beam displacements. Results regarding the performance of the wideband KB optics and of the spectro-microscopy setup are presented, including beam stability issues.

  12. Inelastic processes in Na+-Ne, Na+-Ar, Ne+-Na, and Ar+-Na collisions in the energy range 0.5-14 keV

    NASA Astrophysics Data System (ADS)

    Lomsadze, R. A.; Gochitashvili, M. R.; Kezerashvili, R. Ya.

    2015-12-01

    Absolute cross sections for charge-exchange, ionization, and excitation in Na+-Ne and Na+-Ar collisions were measured in the ion energy range 0.5 -10 keV using a refined version of a capacitor method and collision and optical spectroscopy methods simultaneously in the same experimental setup. Ionization cross sections for Ne+-Na and Ar+-Na collisions are measured at energies of 2 -14 keV using a crossed-beam spectroscopy method. The experimental data and the schematic correlation diagrams are used to analyze and determine the mechanisms for these processes. For the charge-exchange process in Na+-Ar collisions two nonadiabatic regions are revealed and mechanisms responsible for these regions are explained. Structural peculiarity on the excitation function for the resonance lines of argon atoms in Na+-Ar collisions are observed and the possible mechanisms of this phenomenon are explored. The measured ionization cross sections for Na+-Ne and Ne+-Na collisions in conjunction with the Landau-Zener formula are used to determine the coupling matrix element and transition probability in a region of pseudocrossing of the potential curves.

  13. Low-energy Rutherford backscattering-ion channeling measurement system with the use of several tens keV hydrogen and a time-of-flight spectrometer

    NASA Astrophysics Data System (ADS)

    Hasegawa, Masataka; Kobayashi, Naoto; Hayashi, Nobuyuki

    1996-10-01

    We have developed a low-energy Rutherford backscattering spectrometry (RBS)-ion channeling measurement system for the analysis of thin films and solid surfaces with the use of several tens keV hydrogen ions and a time-of-flight spectrometer which was originally developed by Mendenhall and Weller. The depth resolution of our system is better than that of a conventional RBS system with MeV helium ions and silicon surface barrier detectors. This measurement system is very small in size compared to the conventional RBS-ion channeling measurement system with the use of MeV He ions, because of the small ion accelerator for several tens keV ions. The analysis of crystalline thin films which utilizes ion channeling effect can be performed with the use of this low-energy RBS-ion channeling measurement system. The in situ observation of the thermal reaction between iron and silicon substrate with the use of this measurement system is also demonstrated.

  14. 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; Hashimoto, Eiko

    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.

  15. Low-background-rate detector for ions in the 5- to 50-keV energy range to be used for radioisotope dating with a small cyclotron

    SciTech Connect

    Friedman, P.G.

    1986-01-01

    Accelerator mass spectrometry in tandem Van de Graaff accelerators has proven successful for radioisotope dating small samples. Small, inexpensive cyclotrons serving this purpose would make the technique accessible to more researchers and inexpensive enough to compare many small samples. To this end, VC Berkeley is developing a 20-cm-diameter, 30- to 40-keV cyclotron dedicated to high-sensitivity radioisotope dating, initially for /sup 14/C. At this energy, range and dE/dx methods of particle identification are impossible. Thus arises the difficult problem of reliably detecting 30- to 40-keV /sup 14/C at 10/sup -1/ counts/sec in the high-background environment of the cyclotron, where lower energy ions, electrons, and photons bombard the detector at much higher rates. To meet this challenge, an inexpensive, generally useful ion detector was developed that allows dark-count rates below 10/sup -4/ counts/sec and excellent background suppression. With the cyclotron tuned near the /sup 13/CH background peak, to the frequency for /sup 14/C, the detector suppresses the background to 6 x 10/sup -4/ counts/sec. For each /sup 14/C ion, the detector's grazing-incidence Al/sub 2/O/sub 3/ conversion dynode emits about 20 secondary electrons, which are independently multiplied in separate pores of a microchannel plate. The output signal is proportional to the number of secondary electrons, allowing pulse-height discrimination of background.

  16. Energy-dependent dynamics of keV to MeV electrons in the inner zone, outer zone, and slot regions

    DOE PAGESBeta

    Reeves, Geoffrey D.; Friedel, Reiner H. W.; Larsen, Brian A.; Skoug, Ruth M.; Funsten, Herbert O.; Claudepierre, Seth G.; Fennell, Joseph F.; Turner, Drew L.; Denton, Mick H.; Spence, Harlan E.; et al

    2016-01-28

    Here, we present observations of the radiation belts from the Helium Oxygen Proton Electron and Magnetic Electron Ion Spectrometer particle detectors on the Van Allen Probes satellites that illustrate the energy dependence and L shell dependence of radiation belt enhancements and decays. We survey events in 2013 and analyze an event on 1 March in more detail. The observations show the following: (a) at all L shells, lower energy electrons are enhanced more often than higher energies; (b) events that fill the slot region are more common at lower energies; (c) enhancements of electrons in the inner zone are moremore » common at lower energies; and (d) even when events do not fully fill the slot region, enhancements at lower energies tend to extend to lower L shells than higher energies. During enhancement events the outer zone extends to lower L shells at lower energies while being confined to higher L shells at higher energies. The inner zone shows the opposite with an outer boundary at higher L shells for lower energies. Both boundaries are nearly straight in log(energy) versus L shell space. At energies below a few 100 keV, radiation belt electron penetration through the slot region into the inner zone is commonplace, but the number and frequency of “slot filling” events decreases with increasing energy. The inner zone is enhanced only at energies that penetrate through the slot. Energy- and L shell-dependent losses (that are consistent with whistler hiss interactions) return the belts to more quiescent conditions.« less

  17. 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

  18. Dose calculation for photon-emitting brachytherapy sources with average energy higher than 50 keV: Report of the AAPM and ESTRO

    SciTech Connect

    Perez-Calatayud, Jose; Ballester, Facundo; Das, Rupak K.; DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Ouhib, Zoubir; Rivard, Mark J.; Sloboda, Ron S.; Williamson, Jeffrey F.

    2012-05-15

    Purpose: Recommendations of the American Association of Physicists in Medicine (AAPM) and the European Society for Radiotherapy and Oncology (ESTRO) on dose calculations for high-energy (average energy higher than 50 keV) photon-emitting brachytherapy sources are presented, including the physical characteristics of specific {sup 192}Ir, {sup 137}Cs, and {sup 60}Co source models. Methods: This report has been prepared by the High Energy Brachytherapy Source Dosimetry (HEBD) Working Group. This report includes considerations in the application of the TG-43U1 formalism to high-energy photon-emitting sources with particular attention to phantom size effects, interpolation accuracy dependence on dose calculation grid size, and dosimetry parameter dependence on source active length. Results: Consensus datasets for commercially available high-energy photon sources are provided, along with recommended methods for evaluating these datasets. Recommendations on dosimetry characterization methods, mainly using experimental procedures and Monte Carlo, are established and discussed. Also included are methodological recommendations on detector choice, detector energy response characterization and phantom materials, and measurement specification methodology. Uncertainty analyses are discussed and recommendations for high-energy sources without consensus datasets are given. Conclusions: Recommended consensus datasets for high-energy sources have been derived for sources that were commercially available as of January 2010. Data are presented according to the AAPM TG-43U1 formalism, with modified interpolation and extrapolation techniques of the AAPM TG-43U1S1 report for the 2D anisotropy function and radial dose function.

  19. 14-pixel, multiplexed array of gamma-ray microcalorimeters with 47 eV energy resolution at 103 keV

    SciTech Connect

    Doriese, W. B.; Ullom, J. N.; Beall, J. A.; Duncan, W. D.; Ferreira, L.; Hilton, G. C.; Horansky, R. D.; Irwin, K. D.; Mates, J. A. B.; Reintsema, C. D.; Vale, L. R.; Xu, Y.; Zink, B. L.; Rabin, M. W.; Hoover, A. S.; Rudy, C. R.; Vo, D. T.

    2007-05-07

    The authors present a prototype for a high-energy-resolution, high-count-rate, gamma-ray spectrometer intended for nuclear forensics and international nuclear safeguards. The prototype spectrometer is an array of 14 transition-edge-sensor microcalorimeters with an average energy resolution of 47 eV (full width at half maximum) at 103 keV. The resolution of the best pixel is 25 eV. A cryogenic, time-division multiplexer reads out the array. Several important topics related to microcalorimeter arrays are discussed, including cross-talk, the uniformity of detector bias conditions, fabrication of the arrays, and the multiplexed readout. The measurements and calculations demonstrate that a kilopixel array of high-resolution microcalorimeters is feasible.

  20. Array-compatible transition-edge sensor microcalorimeter {gamma}-ray detector with 42 eV energy resolution at 103 keV

    SciTech Connect

    Zink, B. L.; Ullom, J. N.; Beall, J. A.; Irwin, K. D.; Doriese, W. B.; Duncan, W. D.; Ferreira, L.; Hilton, G. C.; Horansky, R. D.; Reintsema, C. D.; Vale, L. R.

    2006-09-18

    The authors describe a microcalorimeter {gamma}-ray detector with measured energy resolution of 42 eV full width at half maximum for 103 keV photons. This detector consists of a thermally isolated superconducting transition-edge thermometer and a superconducting bulk tin photon absorber. The absorber is attached with a technique compatible with producing arrays of high-resolution {gamma}-ray detectors. The results of a detailed characterization of the detector, which includes measurements of the complex impedance, detector noise, and time-domain pulse response, suggest that a deeper understanding and optimization of the thermal transport between the absorber and thermometer could significantly improve the energy resolution of future detectors.

  1. INTEGRAL IGR J18135-1751 = HESS J1813-178: A New Cosmic High-Energy Accelerator from keV to TeV Energies

    NASA Astrophysics Data System (ADS)

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

    2005-08-01

    We report the discovery of a soft gamma-ray source, namely, IGR J18135-1751, detected with IBIS, the Imager on Board the INTEGRAL Satellite. The source is persistent and has a 20-100 keV luminosity of ~5.7× 1034 ergs s-1 (assuming a distance of 4 kpc). 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 counterparts, 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 AGPS 273.4-17.8, showing a power-law spectrum with photon index ~1.8 and a total (Galactic plus intrinsic) absorption corresponding to NH~5×1022 cm-2. We hypothesize that the source is a pulsar wind nebula embedded in its supernova remnant. The lack of X-ray or 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. Based on observations with INTEGRAL, an ESA project with instruments and science data center funded by ESA member states (especially the PI countries: Denmark, France, Germany, Italy, Switzerland, Spain), the Czech Republic, and Poland and with the participation of Russia and the US.

  2. {sup 241}Am(n,{gamma}) cross section in the neutron energy region between 0.02 eV and 300 keV

    SciTech Connect

    Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O' Donnell, J. M.; Haight, R. C.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M.; Macri, R. A.; Wu, C. Y.; Becker, J. A.

    2008-04-17

    The Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL) was used for a neutron capture cross section measurement on {sup 241}Am. The high granularity of the DANCE array (160 BaF2 detectors in a 4{pi} geometry) enables an efficient detection of prompt gamma rays following neutron capture. The preliminary results on the {sup 241}Am(n,{gamma}) cross section are presented from 0.02 eV to 300 keV. The cross section at thermal energy E{sub n} = 0.0253 eV was determined to be 665{+-}33 barns. Resonance parameters were obtained using the SAMMY7 fit to the measured cross section in the resonance region. Significant discrepancies were found between our results and data evaluations for the first three lowest lying resonances. The cross section for neutrons with E{sub n}>l keV agrees well with the ENDF/B-VII.0 and JENDL-3.3 evaluations.

  3. Ionic Liquids as a Reference Material Candidate for the Quick Performance Check of Energy Dispersive X-ray Spectrometers for the Low Energy Range below 1 keV

    PubMed Central

    2016-01-01

    Ionic liquids (ILs) are proposed as simple and efficient test materials to evaluate the performance of energy dispersive X-ray spectrometers (EDS) in the low energy range below 1 keV. By only one measurement, C Kα, N Kα, O Kα, and F Kα X-ray lines can be excited. Additionally, the S Kα line at 2.3 keV and, particularly, the S L series at 149 eV complete the picture with X-ray lines offered by the selected ILs. The well-known (certifiable) elemental composition of the ILs selected in the present study can be used to check the accuracy of results produced with the available EDS quantification routines in the low energy range, simultaneously, for several low atomic number elements. A comparison with other reference materials in use for testing the performance of EDS in the low energy range is included. PMID:27336962

  4. YIELDS OF IONS AND EXCITED STATES IN NONPOLAR LIQUIDS EXPOSED TO X-RAYS OF 1 TO 30 KEV ENERGY

    SciTech Connect

    HOLROYD,R.A.

    1999-08-18

    When x-rays from a synchrotron source are absorbed in a liquid, the x-ray energy (E{sub x}) is converted by the photoelectric effect into the kinetic energy of the electrons released. For hydrocarbons, absorption by the K-electrons of carbon dominates. Thus the energy of the photoelectron (E{sub pe}) is E{sub x}-E{sub b}, where E{sub b} is the K-shell binding energy of carbon. Additional electrons with energy equal to E{sub b} is released in the Auger process that fills the hole in the K-shell. These energetic electrons will produce many ionizations, excitations and products. The consequences of the high density of ionizations and excitations along the track of the photoelectron and special effects near the K-edge are examined here.

  5. 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

  6. Absolute Calibration of Kodak Biomax-MS Film Response to X Rays in the 1.5- to 8-keV Energy Range

    SciTech Connect

    Marshall, F.J.; Knauer, J.P.; Anderson, D.; Schmitt, B.L.

    2006-09-28

    The absolute response of Kodak Biomax-MS film to x rays in the range from 1.5- to 8-keV has been measured using a laboratory e-beam generated x-ray source. The measurements were taken at specific line energies by using Bragg diffraction to produce monochromatic beams of x rays. Multiple exposures were taken on Biomax MS film up to levels exceeding optical densities of 2 as measured by a microdensitometer. The absolute beam intensity for each exposure was measured with a Si(Li) detector. Additional response measurements were taken with Kodak direct exposure film (DEF) so as to compare the results of this technique to previously published calibrations.

  7. Mass attenuation coefficient of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using 16.59 - 25.26 keV photon energy range

    NASA Astrophysics Data System (ADS)

    Mohd Yusof, Mohd Fahmi; Hamid, Puteri Nor Khatijah Abdul; Bauk, Sabar; Hashim, Rokiah; Tajuddin, Abdul Aziz

    2015-04-01

    The Rhizophora spp. particleboards were fabricated using ≤ 104 µm particle size at three different fabrication methods; binderless, steam pre-treated and tannin-added. The mass attenuation coefficient of Rhizophora spp. particleboards were measured using x-ray fluorescent (XRF) photon from niobium, molybdenum, palladium, silver and tin metal plates that provided photon energy between 16.59 to 25.26 keV. The results were compared to theoretical values for water calculated using photon cross-section database (XCOM).The results showed that all Rhizophora spp. particleboards having mass attenuation coefficient close to calculated XCOM for water. Tannin-added Rizophora spp. particleboard was nearest to calculated XCOM for water with χ2 value of 13.008 followed by binderless Rizophora spp. (25.859) and pre-treated Rizophora spp. (91.941).

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

    NASA Astrophysics Data System (ADS)

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

    2004-06-01

    X-ray absorption spectroscopy (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.

  9. Development of 4.5 keV monochromatic X-ray radiography using the high-energy, picosecond LFEX laser

    NASA Astrophysics Data System (ADS)

    Sawada, H.; Fujioka, S.; Hosoda, T.; Zhang, Z.; Arikawa, Y.; Nagatomo, H.; Nishimura, H.; Sunahara, A.; Theobald, W.; Patel, P. K.; Beg, F. N.

    2016-05-01

    Development of a monochromatic x-ray imaging system using a high-energy short- pulse laser LFEX and a spherical crystal is reported. Irradiation of the intense short-pulse laser produces a flash of 4.51 keV Ti K-alpha x-ray while the spherically bent quartz crystal provides a narrow spectral bandwidth and high spatial resolution. This high spatiotemporal imaging technique was applied for recording 2-D monochromatic x-ray images of laser-driven Fast Ignition targets. The results show a sufficiently high spatial resolution to characterize the implosion core, suggesting that the core information extracted from the radiograph images can be used to benchmark a 2-D radiation-hydrodynamic code for accurate hydrodynamic modelling and optimization of FI fuel assembly in the asymmetrical implosion.

  10. Absolute detection efficiency of a microchannel plate detector to X rays in the 1-100 KeV energy range

    NASA Astrophysics Data System (ADS)

    Burginyon, Gary A.; Jacoby, Barry A.; Wobser, James K.; Ernst, Richard; Ancheta, Dione S.; Tirsell, Kenneth G.

    1993-02-01

    There is little information in the literature on the performance of working micro-channel plate (MCP) detectors at high x-ray energies. We have measured the absolute efficiency of a microchannel-plate-intensified, subnanosecond, one dimensional imaging x-ray detector developed at LLNL in the 1 to 100 keV range and at 1.25 MeV. The detector consists of a gold photocathode deposited on the front surface of the MCP (optimized for Ni K(subscript (alpha) ) x rays) to convert x rays to electrons, an MCP to amplify the electrons, and a fast In:CdS phosphor that converts the electron's kinetic energy to light. The phosphor is coated on a fiber-optic faceplate to transmit the light out of the vacuum system. Electrostatic focusing electrodes compress the electron current out of the MCP in one dimension while preserving spatial resolution in the other. The calibration geometry, dictated by a recent experiment, required grazing incidence x rays (15.6 degree(s)) onto the MCP detector in order to maximize deliverable current. The experiment also used a second detector made up of 0.071 in. thick BC422 plastic scintillator material from the Bicron Corporation. We compare the absolute efficiencies of these two detectors in units of optical W/cm(superscript 2) into 4 (pi) per x ray W/cm(superscript 2) incident. At 7.47 keV and 900 volts MCP bias, the MCP detector delivers approximately 1400 times more light than the scintillator detector.

  11. A multilayer grating with a novel layer structure for a flat-field spectrograph attached to transmission electron microscopes in energy region of 2-4 keV

    SciTech Connect

    Imazono, T.; Koike, M.; Koeda, M.; Nagano, T.; Sasai, H.; Oue, Y.; Yonezawa, Z.; Kuramoto, S.; Terauchi, M.; Takahashi, H.; Handa, N.; Murano, T.

    2012-05-17

    A multilayer mirror with a novel layer structure to uniformly enhance the reflectivity in a few keV energy range at a fixed angle of incidence is invented and applied to a multilayer grating for use in a flat-field spectrograph attached to a conventional electron microscope. The diffraction efficiency of the fabricated multilayer grating having the new layer structure is evaluated at the angle of incidence of 88.65 deg. in the energy region of 2.1-4.0 keV. It is shown that the multilayer grating is effective to uniformly enhance the diffraction efficiency and able to be practically used in this energy region.

  12. Learning to Apply Metrology Principles to the Measurement of X-ray Intensities in the 500 eV to 110 keV Energy Range

    SciTech Connect

    Haugh, M. J.; Pond, T.; Silbernagel, C.; Torres, P.; Marlett, K.; Goldin, F.; Cyr, S.

    2011-02-08

    National Security Technologies, LLC (NSTec), Livermore Operations, has two optical radiation calibration laboratories accredited by “the National Voluntary Laboratories Accreditation Program (NVLAP) which is the accrediting body of” the National Institute of Standards and Technology (NIST), and is now working towards accreditation for its X-ray laboratories. NSTec operates several laboratories with X-ray sources that generate X-rays in the energy range from 50 eV to 115 keV. These X-ray sources are used to characterize and calibrate diagnostics and diagnostic components used by the various national laboratories, particularly for plasma analysis on the Lawrence Livermore National Laboratory (LLNL) National Ignition Facility (NIF). Because X-ray photon flux measurement methods that can be accredited, i.e., traceable to NIST, have not been developed for sources operating in these energy ranges, NSTec, NIST, and the National Voluntary Accreditation Program (NVLAP) together have defined a path toward the development and validation of accredited metrology methods for X-ray energies. The methodology developed for the high energy X-ray (HEX) Laboratory was NSTec’s starting point for X-ray metrology accreditation and will be the basis for the accredited processes in the other X-ray laboratories. This paper will serve as a teaching tool, by way of this example using the NSTec X-ray sources, for the process and methods used in developing an accredited traceable metrology.

  13. Observations of the scatter-free solar-flare electrons in the energy range 20-1000 keV

    NASA Technical Reports Server (NTRS)

    Wang, J. R.; Fisk, L. A.; Lin, R. P.

    1971-01-01

    Observations of the scatter-free electron events from solar active region McMath No. 8905 are presented. The measurements were made on Explorer 33 satellite. The data show that more than 80% of the electrons from these events undergo no or little scattering and that these electrons travel only approximately 1.5 a.u. between the sun and the earth. The duration of these events cannot be accounted fully by velocity dispersion alone. It is suggested that these electrons could be continuously injected into interplanetary medium for a time interval of approximately 2 to 3 minutes. Energy spectra of these electrons are discussed.

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

    NASA Astrophysics Data System (ADS)

    Gonzales, Daniel; Cavness, Brandon; Williams, Scott

    2012-03-01

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

  15. High accuracy experimental determination of copper and zinc mass attenuation coefficients in the 100 eV to 30 keV photon energy range

    NASA Astrophysics Data System (ADS)

    Ménesguen, Y.; Gerlach, M.; Pollakowski, B.; Unterumsberger, R.; Haschke, M.; Beckhoff, B.; Lépy, M.-C.

    2016-02-01

    The knowledge of atomic fundamental parameters such as mass attenuation coefficients with low uncertainties, is of decisive importance in elemental quantification using x-ray fluorescence analysis techniques. Several databases are accessible and frequently used within a large community of users. These compilations are most often in good agreement for photon energies in the hard x-ray ranges. However, they significantly differ for low photon energies and around the absorption edges of any element. In a joint cooperation of the metrology institutes of France and Germany, mass attenuation coefficients of copper and zinc were determined experimentally in the photon energy range from 100 eV to 30 keV by independent approaches using monochromatized synchrotron radiation at SOLEIL (France) and BESSY II (Germany), respectively. The application of high-accuracy experimental techniques resulted in mass attenuation coefficient datasets determined with low uncertainties that are directly compared to existing databases. The novel datasets are expected to enhance the reliability of mass attenuation coefficients.

  16. 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.

    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.

  17. The X-ray behaviour of the high-energy peaked BL Lacertae source PKS 2155-304 in the 0.3-10 keV band

    NASA Astrophysics Data System (ADS)

    Kapanadze, B.; Romano, P.; Vercellone, S.; Kapanadze, S.

    2014-10-01

    We present the results of our monitoring of the high-energy peaked BL Lac object PKS 2155-304 by the Swift/X-Ray Telescope (XRT) during 2005-2012. Our timing study shows that the source was highly variable both on longer (weeks-to-months) and intra-day time-scales, up to a factor of 7 in flux, and 30 per cent in fractional variability amplitudes, with no periodic variations. The X-ray spectra are mainly curved with broad ranges of photon index, curvature parameter, and hardness ratio which exhibit significant variability with the flux on different time-scales. Our study of multi-wavelength cross-correlations has revealed that the one-zone SSC scenario seems to be valid for the most optical-to-gamma-ray flares observed during 2006-2012. An `orphan' X-ray flare with no counterpart in other spectral bands suggests the existence of different electron populations. Based on the absence of a correlation between photon index and curvature parameter (expected from the energy-dependent acceleration probability scenario), the observed distribution of curvature parameter from the XRT spectra peaking at b = 0.37, and the observed anti-correlation between the curvature parameter and the 0.3-10 keV flux (i.e. lower curvatures in flaring states), we conclude that the most likely mechanism responsible for producing X-ray emission during the flares is the stochastic acceleration of the electrons.

  18. 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.

  19. 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.

  20. Azimuthal and polar angle dependence of L X-ray differential cross-sections of Yb at 59.54 keV photon energy

    NASA Astrophysics Data System (ADS)

    Akkuş, T.; Şahin, Y.; Yılmaz, D.

    2016-01-01

    The azimuthal and polar angle dependence of L X-ray was investigated in the same experimental setup to remove the existing ambiguity about alignments measurements. We measured Ll, Lα, Lβ and Lγ X-ray differential cross sections of Yb for several different azimuthal angles (30°, 20°, 10°, 0°, -10° and -20°) and polar angles (90°, 100°, 110°, 120°, 130° and 140°) at 59.54 keV photon energy by using a Si(Li) detector. The azimuthal angle dependence of Ll and Lα X-rays were observed. The azimuthal anisotropy of Lβ and Lγ X-rays were not observed. On the other hand, differential cross-sections for Lβ and Lγ X-rays were found independent on the polar angle within experimental error, those for Ll and Lα X-rays depended on the polar angles. Azimuthal and polar angles dependence of L X-ray differential cross-sections contrast with the other experimental and theoretical results, which report evidence of the isotropic emission of Ll and Lα X-rays following photoionization.

  1. Neutron capture and fission cross section of /sup 243/Am in the energy range from 5 to 250 keV

    SciTech Connect

    Wisshak, K.; Kappeler, F.

    1983-11-01

    The neutron capture and subthreshold fission cross section of /sup 243/Am was measured in the energy range from 5 to 250 keV using /sup 197/Au and /sup 235/U as the respective standards. Neutrons were produced via the /sup 7/Li(p,n) and the T(p,n) reaction with the Karlsruhe 3-MV pulsed Van de Graaff accelerator. Capture events were detected by two Moxon-Rae detectors with graphite and bismuth graphite converters, respectively. Fission events were registered by an Ne-213 liquid scintillator with pulse-shape discriminator equipment. Flight paths as short as 50 to 70 mm were used to obtain an optimum signal-to-background ratio. After correction for the different efficiency of the individual converter materials, the capture cross section could be determined with a total uncertainty of 3 to 6%. The respective values for the fission cross section are 8 to 12%. The results are compared to predictions of recent evaluations, which in some cases are severely discrepant.

  2. Saturated ablation in metal hydrides and acceleration of protons and deuterons to keV energies with a soft-x-ray laser

    SciTech Connect

    Andreasson, J.; Iwan, B.; Abreu, E.; Seibert, M. M.; Hajdu, J.; Timneanu, N.; Andrejczuk, A.; Bergh, M.; Caleman, C.; Nelson, A. J.; Bajt, S.; Faeustlin, R. R.; Singer, W.; Toleikis, S.; Tschentscher, T.; Chalupsky, J.; Hajkova, V.; Juha, L.; Chapman, H. N.; Heimann, P. A.

    2011-01-15

    Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 10{sup 17} W/cm{sup 2} were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 10{sup 16} W/cm{sup 2}. This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.

  3. Size saturation in low energy ion beam synthesized nanoparticles in silica glass: 50 keV Ag{sup -} ions implantation, a case study

    SciTech Connect

    Kuiri, P. K.

    2010-09-15

    Fluence-dependent formation of Ag nanoparticles (NPs) in silica glass by 50 keV Ag{sup -} ions implantation has been studied. Samples implanted with fluences of 2x10{sup 16} ions cm{sup -2} and above are found to show an absorption band at around 410 nm, corresponding to the surface plasmon resonance (SPR) of the Ag NPs in silica glass. An increase in SPR peak intensity with increase in fluence has been observed up to a fluence of 7x10{sup 16} ions cm{sup -2} (F7), after which the absorption intensity shows a saturation. Simulations of the optical absorption spectra also indicated an increase in the absorption intensity and hence the size of the NPs with increase in fluence up to F7, beyond which NP size is seen to saturate. The saturation of fluence and the SPR intensity (or NP size) have been explained as coming due to a break up of larger Ag NPs formed near the surface by displacement spikes induced by subsequently incident Ag ions against their regrowth from the movement of Ag atoms toward the surface and their sputtering loss. Further, we have compared our observations with the earlier data on saturation of fluence and size of NPs in cases of Au and Zn, and concluded that the saturation of both fluence and NP size are general phenomena for low energy high fluence metal ion implantation.

  4. Saturated ablation in metal hydrides and acceleration of protons and deuterons to keV energies with a soft-x-ray laser

    NASA Astrophysics Data System (ADS)

    Andreasson, J.; Iwan, B.; Andrejczuk, A.; Abreu, E.; Bergh, M.; Caleman, C.; Nelson, A. J.; Bajt, S.; Chalupsky, J.; Chapman, H. N.; Fäustlin, R. R.; Hajkova, V.; Heimann, P. A.; Hjörvarsson, B.; Juha, L.; Klinger, D.; Krzywinski, J.; Nagler, B.; Pálsson, G. K.; Singer, W.; Seibert, M. M.; Sobierajski, R.; Toleikis, S.; Tschentscher, T.; Vinko, S. M.; Lee, R. W.; Hajdu, J.; Tîmneanu, N.

    2011-01-01

    Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 1017 W/cm2 were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 1016 W/cm2. This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.

  5. Absolute Energy Calibration of X-ray TESs with 0.04 eV Uncertainty at 6.4 keV in a Hadron-Beam Environment

    NASA Astrophysics Data System (ADS)

    Tatsuno, H.; Doriese, W. B.; Bennett, D. A.; Curceanu, C.; Fowler, J. W.; Gard, J.; Gustafsson, F. P.; Hashimoto, T.; Hayano, R. S.; Hays-Wehle, J. P.; Hilton, G. C.; Iliescu, M.; Ishimoto, S.; Itahashi, K.; Iwasaki, M.; Kuwabara, K.; Ma, Y.; Marton, J.; Noda, H.; O'Neil, G. C.; Okada, S.; Outa, H.; Reintsema, C. D.; Sato, M.; Schmidt, D. R.; Shi, H.; Suzuki, K.; Suzuki, T.; Uhlig, J.; Ullom, J. N.; Widmann, E.; Yamada, S.; Zmeskal, J.; Swetz, D. S.

    2016-08-01

    A performance evaluation of superconducting transition-edge sensors (TESs) in the environment of a pion beam line at a particle accelerator is presented. Averaged across the 209 functioning sensors in the array, the achieved energy resolution is 5.2 eV FWHM at Co K_{α } (6.9 keV) when the pion beam is off and 7.3 eV at a beam rate of 1.45 MHz. Absolute energy uncertainty of ± 0.04 eV is demonstrated for Fe K_{α } (6.4 keV) with in-situ energy calibration obtained from other nearby known X-ray lines. To achieve this small uncertainty, it is essential to consider the non-Gaussian energy response of the TESs and thermal cross-talk pile-up effects due to charged particle hits in the silicon substrate of the TES array.

  6. Absolute Energy Calibration of X-ray TESs with 0.04 eV Uncertainty at 6.4 keV in a Hadron-Beam Environment

    NASA Astrophysics Data System (ADS)

    Tatsuno, H.; Doriese, W. B.; Bennett, D. A.; Curceanu, C.; Fowler, J. W.; Gard, J.; Gustafsson, F. P.; Hashimoto, T.; Hayano, R. S.; Hays-Wehle, J. P.; Hilton, G. C.; Iliescu, M.; Ishimoto, S.; Itahashi, K.; Iwasaki, M.; Kuwabara, K.; Ma, Y.; Marton, J.; Noda, H.; O'Neil, G. C.; Okada, S.; Outa, H.; Reintsema, C. D.; Sato, M.; Schmidt, D. R.; Shi, H.; Suzuki, K.; Suzuki, T.; Uhlig, J.; Ullom, J. N.; Widmann, E.; Yamada, S.; Zmeskal, J.; Swetz, D. S.

    2016-01-01

    A performance evaluation of superconducting transition-edge sensors (TESs) in the environment of a pion beam line at a particle accelerator is presented. Averaged across the 209 functioning sensors in the array, the achieved energy resolution is 5.2 eV FWHM at Co K_{α } (6.9 keV) when the pion beam is off and 7.3 eV at a beam rate of 1.45 MHz. Absolute energy uncertainty of ± 0.04 eV is demonstrated for Fe K_{α } (6.4 keV) with in-situ energy calibration obtained from other nearby known X-ray lines. To achieve this small uncertainty, it is essential to consider the non-Gaussian energy response of the TESs and thermal cross-talk pile-up effects due to charged particle hits in the silicon substrate of the TES array.

  7. Calculation of K Shell Intensity Ratios and Line Widths of Ti and some of its compounds by means of 5,96 keV energy

    NASA Astrophysics Data System (ADS)

    Kağan Köksal, Oğuz; Apaydın, Gökhan; Cengiz, Erhan; Karabulut, Kazım

    2016-04-01

    K shell intensity ratios and Line Widths of pure Ti and some of its compounds have been determined experimentally using an Ultra-LEGe detector with resolution 140 eV at 5.9 keV. The samples were excited 5.96 keV photons emitted from a 55Fe radioisotope source with 50 mCi activity. The experimental values of the K shell intensity ratios have been compared with the experimental and theoretical values available in the literature for pure Ti and line widths have been only compared with a theoretical value for pure Ti.

  8. One 17-keV Majorana neutrino?

    NASA Astrophysics Data System (ADS)

    Carlson, Eric; Randall, Lisa

    1991-06-01

    A model is presented accommodating a 17-keV neutrino with 1 percent mixing with the electron neutrino and bounds on the electron-neutrino mass and neutrinoless double-beta decay. However, in contrast to previous models, there is only a single state with mass 17 keV. This model is consistent with cosmological and supernova-cooling constraints, and incorporates the Mikheyev-Smirnov-Wolfenstein explanation of the low solar-neutrino counts. Possible signatures of this model include an excess of muon neutrinos from a supernova explosion, spread over a period of 10-1000 sec, and a Higgs-boson decay signature of leptons plus missing energy.

  9. 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.

    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.

  10. Neutron physics of the Re/Os clock. II. The (n,n') cross section of Os187 at 30 keV neutron energy

    NASA Astrophysics Data System (ADS)

    Mosconi, M.; Heil, M.; Käppeler, F.; Plag, R.; Mengoni, A.

    2010-07-01

    The inelastic neutron-scattering cross section of Os187 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 Li7(p,n)Be7 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 Os187 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 Os187/Re187 pair as a cosmochronometer.

  11. Thick target D-T neutron yield measurements using metal occluders of scandium, titanium, yttrium, zirconium, gadolinium, erbium, hafnium, and tantalum at energies from 25 to 200 keV

    SciTech Connect

    Malbrough, D.J.; Molloy, J.T. Jr.; Becker, R.H.

    1990-11-19

    Deuterium-Tritium (D-T) neutron yields from thick films of scandium, titanium, yttrium, zirconium, gadolinium, erbium, hafnium, and tantalum were measured by the associated particle technique using the 200-keV accelerator at the Pinellas Plant. The neutron yields were measured for all targets at energies from 25 to 200 keV in 5-keV steps with an average uncertainty of {plus_minus}6.8%. Tabulated results are presented with yield versus energy curves for each target. Yield curves for D-D neutrons from earlier measurements are also presented with the D-T neutron yield curves. Good fits to the data were found for both D-D and D-T with theoretical calculations that were adjusted by smooth functions of the form: A{sub 0} + A{sub 1}E + A{sub 2}E{sup 2}. The results of the fits strongly suggest that disagreement between measurement and theory is due mainly to inaccuracies in currently available stopping power data. Comparisons with earlier theoretical calculations for titanium and erbium are also presented. 27 refs., 10 figs., 4 tabs.

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

    NASA Astrophysics Data System (ADS)

    Singh, Amrit; Dhaliwal, A. S.

    2016-02-01

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

  13. Energy dependence of photon-induced Kα and Kβ x-ray production cross-sections for some elements with 42≤Z≤68 in the energy range 38-80 keV

    NASA Astrophysics Data System (ADS)

    Seven, Sabriye; Erdoğan, Hasan

    2015-12-01

    The energy dependence of photon-induced Kα and Kβ x-ray production cross-sections for Mo, Ru, Pd, In, Sb, Cs, La, Pr, Sm, Tb and Er elements has been studied in the energy range of 38-80 keV with secondary excitation method. K x-ray intensities were measured using Energy Dispersive X-Ray Fluorescence (EDXRF) Spectrometry. The measurements have been made by observing the x-ray emissions, with the help of HPGe detector coupled with a multichannel analyzer. The areas of the Kα and Kβ spectral peaks, as well as the net peak areas, have been determined by a fitting process. The measured Kα and Kβ x-ray production cross-sections have been compared with calculated theoretical values in this energy regime. The results have been plotted versus excitation energy. The present experimental Kα and Kβ x-ray production cross-section values for all the elements were in general agreement with the theoretical values calculated using photoionization cross-sections, fluorescence yields and fractional rates based on Hartree-Slater potentials.

  14. 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

  15. Comparison of simulated and measured spectra from an X-ray tube for the energies between 20 and 35 keV

    NASA Astrophysics Data System (ADS)

    Yücel, M.; Emirhan, E.; Bayrak, A.; Ozben, C. S.; Yücel, E. Barlas

    2015-11-01

    Design and production of a simple and low cost X-ray imaging system that can be used for light industrial applications was targeted in the Nuclear Physics Laboratory of Istanbul Technical University. In this study, production, transmission and detection of X-rays were simulated for the proposed imaging device. OX/70-P dental tube was used and X-ray spectra simulated by Geant4 were validated by comparison with X-ray spectra measured between 20 and 35 keV. Relative detection efficiency of the detector was also determined to confirm the physics processes used in the simulations. Various time optimization tools were performed to reduce the simulation time.

  16. A comparison of MCNP4C electron transport with ITS 3.0 and experiment at incident energies between 100 keV and 20 MeV: influence of voxel size, substeps and energy indexing algorithm

    NASA Astrophysics Data System (ADS)

    Schaart, Dennis R.; Jansen, Jan Th M.; Zoetelief, Johannes; de Leege, Piet F. A.

    2002-05-01

    The condensed-history electron transport algorithms in the Monte Carlo code MCNP4C are derived from ITS 3.0, which is a well-validated code for coupled electron-photon simulations. This, combined with its user-friendliness and versatility, makes MCNP4C a promising code for medical physics applications. Such applications, however, require a high degree of accuracy. In this work, MCNP4C electron depth-dose distributions in water are compared with published ITS 3.0 results. The influences of voxel size, substeps and choice of electron energy indexing algorithm are investigated at incident energies between 100 keV and 20 MeV. Furthermore, previously published dose measurements for seven beta emitters are simulated. Since MCNP4C does not allow tally segmentation with the *F8 energy deposition tally, even a homogeneous phantom must be subdivided in cells to calculate the distribution of dose. The repeated interruption of the electron tracks at the cell boundaries significantly affects the electron transport. An electron track length estimator of absorbed dose is described which allows tally segmentation. In combination with the ITS electron energy indexing algorithm, this estimator appears to reproduce ITS 3.0 and experimental results well. If, however, cell boundaries are used instead of segments, or if the MCNP indexing algorithm is applied, the agreement is considerably worse.

  17. Electron Flux Models at GEO: 30 keV - 600 keV

    NASA Astrophysics Data System (ADS)

    Boynton, R.; Balikhin, M. A.; Sibeck, D. G.; Walker, S. N.; Ganushkina, N. Y.

    2015-12-01

    Forecast models are developed for the electron fluxes measured by the Magnetospheric Electron Detector (MagED) onboard the Geostationary Operational Environmental Satellite (GOES) 13. The models employ solar wind and geomagnetic indices as inputs to produce a forecast of the electron flux at Geostationary Earth Orbit (GEO) for five energy ranges from 30 keV - 600 keV. All of these models will be implemented in real time to forecast the electron fluxes on the PROGRESS project website (https://ssg.group.shef.ac.uk/progress2/html/index.phtml).

  18. Experimental and theoretical studies of the He(2+)-He system - Differential cross sections for direct, single-, and double-charge-transfer scattering at keV energies

    NASA Technical Reports Server (NTRS)

    Gao, R. S.; Dutta, C. M.; Lane, N. F.; Smith, K. A.; Stebbings, R. F.; Kimura, M.

    1992-01-01

    Measurements and calculations of differential cross sections for direct scattering, single-charge transfer, and double-charge transfer in collisions of 1.5-, 2.0-, 6.0-, and 10.0-keV (He-3)2+ with an He-4 target are reported. The measurements cover laboratory scattering angles below 1.5 deg with an angular resolution of about 0.03 deg. A quantum-mechanical molecular-state representation is employed in the calculations; in the case of single-charge transfer a two-state close-coupling calculation is carried out taking into account electron-translation effects. The theoretical calculations agree well with the experimental results for direct scattering and double-charge transfer. The present calculation identifies the origins of oscillatory structures observed in the differential cross sections.

  19. On the possibility of the generation of high harmonics with photon energies greater than 10 keV upon interaction of intense mid-IR radiation with neutral gases

    SciTech Connect

    Emelina, A S; Emelin, M Yu; Ryabikin, M Yu

    2014-05-30

    Based on the analytical quantum-mechanical description in the framework of the modified strong-field approximation, we have investigated high harmonic generation of mid-IR laser radiation in neutral gases taking into account the depletion of bound atomic levels of the working medium and the electron magnetic drift in a high-intensity laser field. The possibility is shown to generate high-order harmonics with photon energies greater than 10 keV under irradiation of helium atoms by intense femtosecond laser pulses with a centre wavelength of 8 – 10.6 μm. (interaction of radiation with matter)

  20. Neutron capture cross sections of natural Yb, /sup 170/Yb, /sup 175/Lu, and /sup 184/W in the energy range from 5 to 200 keV for the /sup 176/Lu-chronometer

    SciTech Connect

    Beer, H.; Wisshak, K.; Kaeppeler, F.

    1980-09-01

    The neutron capture cross sections of natural Yb, /sup 170/Yb, /sup 175/Lu and /sup 184/W have been measured in the keV neutron energy range with a pulsed Van de Graaff accelerator using the kinematically collimated neutron beam from the /sup 7/Li(p,n) and the T(p,n) reaction. Prompt capture gamma rays were registered by a Moxon-Rae detector. All measurements were performed in a single run relative to the /sup 197/Au cross section as a standard. The cross sections of /sup 175/Lu and /sup 170/Yb were used to investigate the /sup 176/Lu-cosmic clock.

  1. Schwinger variational approach for a direct excitation of hydrogen-like (Li2+ (1s)) target to the level n=3 by proton impact energies from 9 keV to 3 MeV

    NASA Astrophysics Data System (ADS)

    Khelfaoui, Friha; Lasri, Boumediene; Abbes, Oukacha

    2012-06-01

    The excitation cross sections for hydrogen-like (Li2+(1s)) to the 3s, 3p and 3d states by proton impact have been calculated in a wide energy range from 9 keV to 3 MeV, using the Schwinger's variational principle within the impact parameter formalism. These cross sections are relevant to controlled nuclear fusion studies [1]. The behaviors of the computed cross sections are in excellent agreement with available theoretical results, obtained by close-coupling method which is those of TCAO of Ermolaev et al [1] and SCE of Hall et al [2].

  2. Effective atomic numbers, water and tissue equivalence properties of human tissues, tissue equivalents and dosimetric materials for total electron interaction in the energy region 10 keV-1 GeV.

    PubMed

    Kurudirek, Murat

    2014-12-01

    Effective atomic numbers (Zeff) of 107 different materials of dosimetric interest have been calculated for total electron interactions in the wide energy region 10keV-1GeV. The stopping cross sections of elements and dosimetric materials were used to calculate Zeff of the materials. Differences (%) in Zeff relative to water have been calculated in the entire energy region to evaluate the water equivalency of the used materials. Moreover, the tissue equivalent materials have been compared with the tissues and dosimetric materials in terms of Zeff to reveal their ability to use as tissue substitutes. Possible conclusions were drawn based on the variation of Zeff through the entire energy region and water and tissue equivalency comparisons in terms of Zeff. PMID:25061891

  3. Transmission images and evaluation of tomographic imaging based scattered radiation from biological materials using 10, 15, 20 and 25 keV synchrotron X-rays: An analysis in terms of optimum energy

    SciTech Connect

    Rao, Donepudi V.; Akatsuka, Takao; Tromba, Giuliana

    2004-05-12

    Transmission images and tomographic imaging based scattered radiation is evaluated from biological materials, for example, Polyethylene, Poly carbonate, Plexiglas and Nylon using 10, 15, 20 and 25 keV synchrotron X-rays. The SYRMEP facility at Elettra,Trieste, Italy and the associated detection system has been used for the image acquisition. The scattered radiation is detected for each sample at three energies at an angle of 90 deg. using Si-Pin detector coupled to a multi-channel analyzer. The contribution of transmitted, Compton and fluorescence photons are assessed for a test phantom of small dimensions. The optimum analysis is performed with the use of the dimensions of the sample and detected radiation at various energies.

  4. Characteristics of Protons Exiting from a Polyethylene Converter Irradiated by Neutrons with Energies between 1 keV and 10 MeV.

    PubMed

    Nikezic, D; Shahmohammadi Beni, Mehrdad; Krstic, D; Yu, K N

    2016-01-01

    Monte Carlo method has been used to determine the efficiency for proton production and to study the energy and angular distributions of the generated protons. The ENDF library of cross sections is used to simulate the interactions between the neutrons and the atoms in a polyethylene (PE) layer, while the ranges of protons with different energies in PE are determined using the Stopping and Range of Ions in Matter (SRIM) computer code. The efficiency of proton production increases with the PE layer thickness. However the proton escaping from a certain polyethylene volume is highly dependent on the neutron energy and target thickness, except for a very thin PE layer. The energy and angular distributions of protons are also estimated in the present paper, showing that, for the range of energy and thickness considered, the proton flux escaping is dependent on the PE layer thickness, with the presence of an optimal thickness for a fixed primary neutron energy. PMID:27362656

  5. Characteristics of Protons Exiting from a Polyethylene Converter Irradiated by Neutrons with Energies between 1 keV and 10 MeV

    PubMed Central

    Nikezic, D.; Shahmohammadi Beni, Mehrdad; Krstic, D.; Yu, K. N.

    2016-01-01

    Monte Carlo method has been used to determine the efficiency for proton production and to study the energy and angular distributions of the generated protons. The ENDF library of cross sections is used to simulate the interactions between the neutrons and the atoms in a polyethylene (PE) layer, while the ranges of protons with different energies in PE are determined using the Stopping and Range of Ions in Matter (SRIM) computer code. The efficiency of proton production increases with the PE layer thickness. However the proton escaping from a certain polyethylene volume is highly dependent on the neutron energy and target thickness, except for a very thin PE layer. The energy and angular distributions of protons are also estimated in the present paper, showing that, for the range of energy and thickness considered, the proton flux escaping is dependent on the PE layer thickness, with the presence of an optimal thickness for a fixed primary neutron energy. PMID:27362656

  6. Neutron Capture Cross-Section Measurement of Rhodium in the Energy Region from 0.003 eV to 80 keV by Linac Time-of-Flight Method

    SciTech Connect

    Lee, Samyol; Yamamoto, Shuji; Kobayashi, Katsuhei; Kim, Guinyun; Chang, Jonghwa

    2003-05-15

    The neutron capture cross section of rhodium has been measured in the energy region from 0.003 eV to 80 keV by the neutron time-of-flight method with a 46-MeV electron linear accelerator of the Kyoto University, Research Reactor Institute. An assembly of Bi{sub 4}Ge{sub 3}O{sub 12} (BGO) scintillators, which was composed of 12 pieces of BGO and placed at a distance 12.7 {+-} 0.02 m from the neutron source, was employed as a total energy absorption detector for the prompt capture gamma-ray measurement from the sample. In order to determine the neutron flux impinging on the capture sample, a plug of {sup 10}B powder sample and the {sup 10}B(n, {alpha}{gamma}) standard cross section were used.The existing experimental data and evaluated capture cross sections in ENDF/B-VI, JENDL-3.2, and JEF-2.2 have been compared with the current measurement. Popov and Shapiro obtained poor energy resolution data in the resonance region with a lead slowing-down spectrometer. Furthermore, their data are a little higher than the current values above {approx}1 keV. The experimental data measured by Weston et al., Hockenbury et al., Macklin and Halperin, Fricke et al., and Block et al. are somewhat higher than the current values. The data measured by Moxon and Rae are somewhat lower than the current values above {approx}100 eV. The data measured by Wisshak et al. and Bokhovko et al. are in general agreement with the measurement above 4 keV within the experimental error. The evaluated data in ENDF/B-VI, JENDL-3.2, and JEF-2.2 have been in good agreement with the current result, although the JENDL-3.2 and the JEF-2.2 values are somewhat lower than the measurement in the cross section minimum region from 10 to 100 eV.The thermal neutron cross sections (2200 m/s values) measured by Seren et al. and Walker et al. are in good agreement with the current measurement (133.0 {+-} 0.93 b) within the experimental error. Other experimental data and the evaluated data are discrepant by 9 to 29% from

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

    SciTech Connect

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

    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.

  8. Interplanetary variability in particle fluxes recorded by the low energy charged particle detector SLED (about 30 keV to greater than 30 MeV) during the Cruise Phase of the PHOBOS Mission to Mars and its moons

    NASA Astrophysics Data System (ADS)

    McKenna-Lawlor, S. M. P.; Afonin, V. V.; Gringauz, K. I.; Keppler, E.; Kirsch, E.; Richter, A. K.; Witte, M.; O'Sullivan, D.; Thompson, A.; Kecskemety, K.

    1991-05-01

    Two lightweight telescope detector systems, codenamed SLED-1 and SLED-2, with the capability to monitor electron and ion fluxes within an energy range spanning 34 keV to a few tens of MeV, were launched on the twin spacecraft of the Soviet Phobos Mission to Mars and its moons in July 1988. Solar-related particle enhancements recorded during the Cruise Phase, and also in the near Martian environment, over the interval 19 July 1988-27 March 1989 while the interplanetary medium was in course of changing over from solar-minimum to solar-maximum dominated conditions, are presented. In particular, examples of signatures characterizing events associated with each of these phenomenological states are provided in the context of attempting to elucidate how the solar interplanetary medium evolves from one condition to the other.

  9. Mass attenuation coefficient of binderless, pre-treated and tannin-based Rhizophora spp. particleboards using 16.59 – 25.26 keV photon energy range

    SciTech Connect

    Mohd Yusof, Mohd Fahmi Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz; Bauk, Sabar; Hashim, Rokiah

    2015-04-29

    The Rhizophora spp. particleboards were fabricated using ≤ 104 µm particle size at three different fabrication methods; binderless, steam pre-treated and tannin-added. The mass attenuation coefficient of Rhizophora spp. particleboards were measured using x-ray fluorescent (XRF) photon from niobium, molybdenum, palladium, silver and tin metal plates that provided photon energy between 16.59 to 25.26 keV. The results were compared to theoretical values for water calculated using photon cross-section database (XCOM).The results showed that all Rhizophora spp. particleboards having mass attenuation coefficient close to calculated XCOM for water. Tannin-added Rizophora spp. particleboard was nearest to calculated XCOM for water with χ2 value of 13.008 followed by binderless Rizophora spp. (25.859) and pre-treated Rizophora spp. (91.941)

  10. 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.

  11. Experimental study of interactions of highly charged ions with atoms at keV energies. Progress report, July 1, 1991--June 30, 1992

    SciTech Connect

    Kostroun, V.O.

    1992-07-05

    This Progress Report describes the experimental work carried out, and the work in progress, at the Cornell EBIS Laboratory during the period 7/1/1991 to 6/30/1992. During this period, a number of experiments were carried out. The absolute values of the total, one, two and three electron transfer cross sections for highly charged argon ions (8{le}q{le}16) colliding with argon at 2.3 qkev laboratory energy were measured. The distribution of recoil ions and molecular fragments formed in highly charged ion atom and molecule collisions was measured in order to help the interpretation of electron spectra in the 40--320 eV energy range emitted in Ar{sup q+}+Ar(8{le}q{le}16) collisions at 2.3 qkeV that were measured in our laboratory. The interpretation of the electron spectra is still under way. A new collision chamber was built which contains an ion decelerating lens system and a high resolution monochromator-analyzer combination. Ions extracted from the Cornell Electron Beam Ion Source were successfully decelerated from 2.3 qkeV down to 30 qeV Preliminary 0{degree} translational energy spectra for Ar{sup l2+} on Ar at a collision energy of 38.6 qeV show a 0.56 qeV resolution. Work is in progress to extend measurements of cross sections and recoil ion charge state distributions down to collision energies in the 10 eV/amu range.

  12. Comparison of some lead and non-lead based glass systems, standard shielding concretes and commercial window glasses in terms of shielding parameters in the energy region of 1 keV-100 GeV: A comparative study

    NASA Astrophysics Data System (ADS)

    Kurudirek, Murat; Özdemir, Yüksel; Şimşek, Önder; Durak, Rıdvan

    2010-12-01

    The effective atomic numbers, Z eff of some glass systems with and without Pb have been calculated in the energy region of 1 keV-100 GeV including the K absorption edges of high Z elements present in the glass. Also, these glass systems have been compared with some standard shielding concretes and commercial window glasses in terms of mean free paths and total mass attenuation coefficients in the continuous energy range. Comparisons with experiments were also provided wherever possible for glasses. It has been observed that the glass systems without Pb have higher values of Z eff than that of Pb based glasses at some high energy regions even if they have lower mean atomic numbers than Pb based glasses. When compared with some standard shielding concretes and commercial window glasses, generally it has been shown that the given glass systems have superior properties than concretes and window glasses with respect to the radiation-shielding properties, thus confirming the availability of using these glasses as substitutes for some shielding concretes and commercial window glasses to improve radiation-shielding properties in the continuous energy region.

  13. Calculation of proton total reaction cross sections for some target nuclei in incident energy range of 10-600 MeV

    SciTech Connect

    Bueyuekuslu, H.; Kaplan, A.; Aydin, A.; Tel, E.; Yildirim, G.

    2010-10-15

    In this study, proton total reaction cross sections have been investigated for some isotopes such as {sup 12}C, {sup 27}Al, {sup 9}Be, {sup 16}O, {sup 181}Ta, {sup 197}Au, {sup 6}Li, and {sup 14}N by a proton beam up to 600 MeV. Calculation of the proton total cross sections has been carried out by the analytic expression formulated by M.A. Alvi by using Coulomb-modified Glauber theory with the Helm model nuclear form factor. The obtained results have been discussed and compared with the available experimental data and found to be in agreement with each other.

  14. Fine pitch transition-edge sensor X-ray microcalorimeters with sub-eV energy resolution at 1.5 keV

    NASA Astrophysics Data System (ADS)

    Lee, S. J.; Adams, J. S.; Bandler, S. R.; Chervenak, J. A.; Eckart, M. E.; Finkbeiner, F. M.; Kelley, R. L.; Kilbourne, C. A.; Porter, F. S.; Sadleir, J. E.; Smith, S. J.; Wassell, E. J.

    2015-11-01

    We are developing arrays of X-ray microcalorimeters on a 50-µm pitch that utilize transition-edge sensors as the sensor to measure the temperature rise when X-rays are absorbed. An array of this type of pixel has great potential for the study of point sources in future X-ray observatory missions. The pixels have gold absorbers with dimensions 45 × 45 × 4.2 µm3. We measured an energy resolution of 0.72 ± 0.03 eV full width at half maximum for the Al Kα complex in a subset of pixels within the array, which is the best resolution to date using a non-dispersive detector at this energy. We describe our characterization of this device including measurements of the heat capacity, thermal conductance to the heat bath, and the temperature and current sensitivity of the detector, and discuss its potential for improved performance.

  15. 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.

  16. Observations of celestial X-ray sources above 20 keV with the high-energy scintillation spectrometer on board OSO 8

    NASA Technical Reports Server (NTRS)

    Crannell, C. J.; Dennis, B. R.; Dolan, J. H.; Frost, K. J.; Orwig, L. E.; Beall, J. H.; Maurer, G. S.

    1977-01-01

    High-energy X-ray spectra of the Crab Nebula, Cyg- XR-1, and Cen A were determined from observations with the scintillation spectrometer on board the OSO-8 satellite, launched in June, 1975. Each of these sources was observed over two periods of 8 days or more, enabling a search for day-to-day and year to year variations in the spectral and temporal characteristics of the X-ray emission. No variation in the light curve of the Crab pulsar was found from observations which span a 15-day period in March 1976, with demonstrable phase stability. Transitions associated with the binary phase of Cyg XR-1 and a large change in the emission from Con A are reported.

  17. Seeded quantum FEL at 478 keV

    SciTech Connect

    Guenther, M. M.; Jentschel, M.; Thirolf, P. G.; Seggebrock, T.; Habs, D.

    2012-07-09

    We present for the first time the concept of a seeded {gamma} quantum Free-Electron-Laser (QFEL) at 478 keV, which has very different properties compared to a classical. The basic concept is to produce a highly brilliant {gamma} beam via SASE. To produce highly intense and coherent {gamma} beam, we intend to use a seeded FEL scheme. Important for the production of such a {gamma} beam are novel refractive {gamma}-lenses for focusing and an efficient monochromator, allowing to generate a very intense and coherent seed beam. The energy of the {gamma} beam is 478 keV, corresponding to a wavelength in the sub-Angstrom regime (1/38 A). To realize a coherent {gamma} beam at 478 keV, it is necessary to use a quantum FEL design. At such high radiation energies a classical description of the {gamma}-FEL becomes wrong.

  18. Measurement of the 13C(α, 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 β-decays. The 13C(α, 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(α, 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{α 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(α, n)16O astrophysical factor. A preliminary analysis of a partial data set has lead to {( {tilde C{α 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(α, n)16O reaction rate in agreement with the most results in the literature at ˜ 108 K, with enhanced accuracy thanks to this innovative approach.

  19. High-contrast process using a positive-tone resist with antistatic coating and high-energy (100-keV) e-beam lithography for fabricating diffractive optical elements (DOE) on quartz

    NASA Astrophysics Data System (ADS)

    Poli, Louis C.; Kondek, Christine A.; Shoop, Barry L.; McLane, George F.

    1995-06-01

    Diffractive optical elements (DOE) are becoming important as optical signal processing elements in increasingly diverse applications. These elements, fabricated on quartz, may be used as phase shift type masks or as embedded components that implement a transfer function within a processing network. A process is under development for the fabrication of a DOE implementing a Jervis error diffusion kernel for research in half tone image processing. Dry etching is performed after lithography and pattern transfer through a nickel mask. This results in etched areal features on the substrate. An optical diffraction medium is thus created. Lithographic patterning is done by e-beam lithography (EBL) to realize small features, but also offers the important advantage of a large depth of field which relaxes the problem of complex surface topology. The recent availability of high energy (100 KeV) lithography tools provides a capability for precision overlay, small feature resolution, and enhanced image contrast through a lower induced proximity effect. Patterning by EBL on insulating substrates is complicated by the necessity of providing a vehicle for the avoidance of charge buildup on the surface. In a previously presented paper a methodology was shown for the use of TQV-501 (Nitto Chemical) antistatic compound as a final spin on film for use with PMMA and SAL-601 (Shipley). In this current work, a process is described using EBL and a high performance positive resist working with a final film layer of antistatic TQV-501 on a nickel coated wafer. The process may then be reapplied to realize additional lithographic levels in registration, for multilevel DOE components. High energy (100 KeV) EBL is used to provide high quality pattern definition. The e-beam sensitive resist, ZEP-320-37 (Nagase Chemical) in dilution, together with a top film layer of TQV-501 serves as a bilevel resist system and is used for patterning the desired image before definition of the nickel mask through

  20. Measurement of mass attenuation coefficients of Rhizophora spp. binderless particleboards in the 16.59-25.26 keV photon energy range and their density profile using x-ray computed tomography.

    PubMed

    Marashdeh, M W; Bauk, S; Tajuddin, A A; Hashim, R

    2012-04-01

    The mass attenuation coefficients of Rhizophora spp. binderless particleboard with four different particle sizes (samples A, B, C and D) and natural raw Rhizophora spp. wood (sample E) were determined using single-beam photon transmission in the energy range between 16.59 and 25.26 keV. This was done by determining the attenuation of K(α1) X-ray fluorescent (XRF) photons from niobium, molybdenum, palladium, silver and tin targets. The results were compared with theoretical values of young-age breast (Breast 1) and water calculated using a XCOM computer program. It was found that the mass attenuation coefficient of Rhizophora spp. binderless particleboards to be close to the calculated XCOM values in water than natural Rhizophora spp. wood. Computed tomography (CT) scans were then used to determine the density profile of the samples. The CT scan results showed that the Rhizophora spp. binderless particleboard has uniform density compared to natural Rhizophora spp. wood. In general, the differences in the variability of the profile density decrease as the particle size of the pellet samples decreases. PMID:22304963

  1. 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.

  2. 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.

  3. Surface morphology changes and damage in hot tungsten by impact of 80 eV - 12 keV He-ions and keV-energy self-atoms

    NASA Astrophysics Data System (ADS)

    Hijazi, Hussein; Bannister, Mark E.; Krstic, Predrag S.; Parish, Chad M.; Meyer, Harry M., III; Meyer, Fred M.

    2013-10-01

    We report on measurements of interactions of 50 - 12,000 eV He ions with heated tungsten surfaces performed at the ORNL MIRF. Surface morphology changes, as well as nano-fuzz formation were investigated as function of flux and total fluence, for both virgin and pre-damaged W-targets. At low fluences, ordered surface structures are observed, with great grain-to-grain variability, together with blisters and pinholes, whose density and size increase with increasing fluence. At larger fluences, individual grain characteristics disappear, and the entire surface assumes a frothy appearance in FIB/SEM, with a multitude of near-surface bubbles with a broad range of sizes, and disordered whisker growth, while in SEM imaging the surface is indistinguishable from nano-fuzz produced on linear plasma devices. These features are evident at progressively lower fluences as the He-ion energy is increased, particularly above 1 keV, where the He beam serves not only to load the near-surface region with He to saturation, but to produce significant near-surface damage sites that can trap He. We also report on observations of the effects on surface morphology changes and nano-fuzz formation of pre-damage created by self-ion impact, and on MD simulations of near-surface damage using self-atoms. Research sponsored by the LDRD Program of ORNL, managed by UT-Battelle, LLC, for the US DOE.

  4. 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, Γgsim 1200, using simple γγ 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 Γ >~ 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.

  5. FERMI OBSERVATIONS OF GRB 090510: A SHORT-HARD GAMMA-RAY BURST WITH AN ADDITIONAL, HARD POWER-LAW COMPONENT FROM 10 keV TO GeV ENERGIES

    SciTech Connect

    Ackermann, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A.; Asano, K.; Atwood, W. B.; Axelsson, M.; Baldini, L.; Bellazzini, R.; Bregeon, J.; Ballet, J.; Baring, M. G.; Bastieri, D.; Bhat, P. N.; Bissaldi, E.; Bonamente, E. E-mail: sylvain.guiriec@lpta.in2p3.f E-mail: ohno@astro.isas.jaxa.j

    2010-06-20

    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{sub 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 {approx}20 keV and above {approx}100 MeV. The onset of the high-energy spectral component appears to be delayed by {approx}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{sup +5.8}{sub -2.6} GeV, the highest ever measured from a short GRB. Observation of this photon sets a minimum bulk outflow Lorentz factor, {Gamma}{approx_gt} 1200, using simple {gamma}{gamma} opacity arguments for this GRB at redshift z = 0.903 and a variability timescale on the order of tens of ms for the {approx}100 keV-few MeV flux. Stricter high confidence estimates imply {Gamma} {approx_gt} 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.

  6. 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.

  7. 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.

  8. Energetic electron fluxes (E180 KeV) observed by the Giotto experiment EPA during encounter with Comet Halley

    NASA Astrophysics Data System (ADS)

    Kirsch, E.; McKenna-Lawlor, S.; Thompson, A.; Osullivan, D.; Neubauer, F. M.

    1986-12-01

    The Energetic Particle Detector system EPA/EPONA onboard Giotto detects ions and electrons with energies greater than 20 keV in various energy channels. In this paper, electron fluxes are presented together with data from the Giotto Magnetometer Experiment. Electrons >180 keV were recorded from the transit of the foreshock, inbound, until the last observation outbound at approximately 03:00 UT on 15 March 1986. Energy spectra for the inbound pass are shown. One flux enhancement in the >300 keV channel and several in the >180 keV channel were recorded outbound. Possible acceleration mechanisms for the energetic electrons are considered.

  9. 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.

  10. Measurement of photon mass attenuation coefficients of plutonium from 60 to 2615 keV

    NASA Astrophysics Data System (ADS)

    Rettschlag, M.; Berndt, R.; Mortreau, P.

    2007-11-01

    Measurements have been made to determine plutonium photon mass attenuation coefficients by using a collimated-beam transmission method in the energy range from 60 to 2615 keV. These experimental results were compared with previous experimental and theoretical data. Good agreements are observed in the 240-800 keV energy range, whereas differences up to maximum 10% are observed out of these limits.

  11. Stacked depth graded multilayer for hard X-rays measured up to 130 keV

    NASA Astrophysics Data System (ADS)

    Jensen, C. P.; Christensen, F. E.; Romaine, S.; Bruni, R.; Zhong, Z.

    2007-09-01

    Depth graded multilayer designs for hard x-ray telescopes in the 10 keV to 70-80 keV energy range have had either W or Pt as the heavy element. These materials have been chosen because of reasonable optical constants, the possibility to grow smooth interfaces with the spacer material, and the stability over time. On the flip side both W and Pt have an absorption edge -- 69.5 keV (W) and 78.4 keV (Pt) -- which is very close to the two 44Ti lines at 67.9 keV and 78.4 keV that are produced in the envelope of a super nova explosion. Other materials have better optical constants and no absorption edges in this energy range, for example Ni 0.93V 0.07, but are not used because of high interface roughness. By using a WC/SiC multilayer for the bottom and a Ni 0.93V 0.07/SiC multilayer for the thicker top layers of a depth graded multilayer we have made a reflector that doesn't have a clear absorption edge. This reflector has been measured at energies between 8 keV and 130 keV. At a graze angle of 0.11 degree there is still nearly the same reflectivity below the W absorption edge as for a traditional W based coating, and above the W absorption edge there is still 48% reflection at 80 keV.

  12. 40-keV electron durable trapping electron

    SciTech Connect

    Feynman, J.; Hardy, D.A.; Mullen, E.G.

    1984-03-01

    The positron and extent of the region in which electrons with energies less than 40-keV are durably trapped in the nightside magnetosphere is found for both normal and disturbed geomagnetic conditions by using data from the P78-2 (SCATHA) satellite. The region of the magnetosphere from 5.3 to 7.9 R/sub E/ was studied. In this region neither solar-magnetic nor geocentric-solar magnetospheric coordinates order the data satisfactorily. A new coordinate systems called composite coordinates is introduced. It takes account of the fact that this region of the magnetosphere is strongly influenced by both the earth's ddipole field and the direction of the solar wind. In composite coordinates when Kp< or =4+, 40-keV electron fluxes were almost continuously present in a region centered on the equatorial palne and 1.2 R/sub E/ in half width. At larger composite coordinate latitudes there is another region more than 1 R/sub E/ thick within which 40-keV electron fluxes routinely appear and disappear on time scales of one hour as the trapping boundary actively moves over the satellite. We have no evidence that SCATHA over entered the tail lobes where no particles are trapped. When Kp> or =6- the region in which 40-keV electron fluxes were always present moved earthward and/or thinned but remained ordered in composite coordinates. We suggest that the new coordinate system will be useful for ordering other data sets taken in this region of the magnetosphere.

  13. X-ray mass attenuation coefficients and imaginary components of the atomic form factor of zinc over the energy range of 7.2-15.2 keV

    SciTech Connect

    Rae, Nicholas A.; Chantler, Christopher T.; Barnea, Zwi; Jonge, Martin D. de; Tran, Chanh Q.; Hester, James R.

    2010-02-15

    The x-ray mass attenuation coefficients of zinc are measured in a high-accuracy experiment between 7.2 and 15.2 keV with an absolute accuracy of 0.044% and 0.197%. This is the most accurate determination of any attenuation coefficient on a bending-magnet beamline and reduces the absolute uncertainty by a factor of 3 compared to earlier work by advances in integrated column density determination and the full-foil mapping technique described herein. We define a relative accuracy of 0.006%, which is not the same as either the precision or the absolute accuracy. Relative accuracy is the appropriate parameter for standard implementation of analysis of near-edge spectra. Values of the imaginary components f'' of the x-ray form factor of zinc are derived. Observed differences between the measured mass attenuation coefficients and various theoretical calculations reach a maximum of about 5% at the absorption edge and up to 2% further than 1 keV away from the edge. The measurements invite improvements in the theoretical calculations of mass attenuation coefficients of zinc.

  14. Heliospheric Neutral Atom Spectra Between 0.01 and 6 keV fom IBEX

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Allegrini, F.; Bzowski, M.; Funsten, H. O.; Ghielmetti, A. G.; Gloeckler, G.; Heirtzler, D.; Janzen, P.; Kubiak, M.; Kucharek, H.; McComas, D. J.; Moebius, E.; Moore, T. E.; Petrinec, S. M.; Quinn, M.; Reisenfeld, D.; Saul, L. A.; Scheer, J. A.; Schwardron, N.; Trattner, K. J.; Vanderspek, R.; Wurz, P.

    2012-01-01

    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.

  15. Measurement of mass attenuation coefficients for four mixtures using X-rays from 13 keV up to 40 keV

    NASA Astrophysics Data System (ADS)

    Angelone, M.; Esposito, A.; Chiti, M.; Gentile, A.

    2001-06-01

    The total absorption coefficients for some selected organic compounds relevant to health physics, Triaflol BN (C 3H 4O 2) n, Triaflol TN (C 12H 18O 7) n, Kapton (C 44H 20O 10) n, and Melinex (C 10H 8N 4O 4) n were measured in the X-ray energy range from 13 keV up to about 40 keV using a collimator, high purity germanium detector with thin Be window and variable energy X-ray source. The measured values are compared with the theoretical ones obtained using the XCOM code. The agreement is generally good within a few percent.

  16. Gel behavior of keV ion irradiated polystyrene

    SciTech Connect

    Calcagno, L.; Foti, G.; Licciardello, A.; Puglisi, O.

    1988-10-17

    Among the chemical and physical modifications induced by ion bombardment of polymers, the solubility changes are very important because of technological application for lithography in microelectronic devices. Solubility changes due to the occurrence of crosslinkings have been followed on monodisperse and polydisperse polystyrene after ion irradiations (10/sup 11/--10/sup 14/ ions/cm/sup 2/, keV energy). By using the Inokuty gel theory (M. Inokuti J. Appl. Phys. 38, 2999 (1963)), the chemical yield (crosslinking/eV) has been determined for different molecular weights and molecular weight distributions.

  17. The Average 0.5-200 keV Spectrum of AGNs at 0

    NASA Astrophysics Data System (ADS)

    Ballantyne, David R.

    2013-04-01

    The X-ray spectra of AGNs span nearly three decades in energy and are comprised of many separate components: a power-law with a high energy cutoff, reflection from the accretion disk as well as distant material, and, in many cases, a soft excess. Aside from a small number of bright sources observed with BeppoSAX, the full energy range of AGN spectra has only been studied in piecemeal by a fleet of X-ray observatories that can only focus on a small part of the entire spectrum. Therefore, while catalogues of the spectral properties of hundreds of AGNs have been published in different energy bands, these results are isolated from one another and a clear picture of the broadband spectral properties of typical AGNs remains elusive. In this work, we make use of the 0 X-ray luminosity functions of AGNs in the 0.5-2 keV, 2-10 keV, 3-20 keV, 15-55 keV and 14-195 keV bands to construct the spectral model of an average AGN that can simultaneously account for all 5 luminosity functions. Enhanced iron abundances, disk reflection, and the presence or absence of the X-ray Baldwin Effect are considered, along with the traditional parameters of photon index and cutoff energy. Applications to X-ray background modelling and AGN physics are discussed.

  18. Charge dynamics of MgO single crystals subjected to KeV electron irradiation

    NASA Astrophysics Data System (ADS)

    Boughariou, A.; Blaise, G.; Braga, D.; Kallel, A.

    2004-04-01

    A scanning electron microscope has been equipped to study the fundamental aspects of charge trapping in insulating materials, by measuring the secondary electron emission (SEE) yield σ with a high precision (a few percent), as a function of energy, electron current density, and dose. The intrinsic secondary electron emission yield σ0 of uncharged MgO single crystals annealed at 1000 °C, 2 h, has been studied at four energies 1.1, 5, 15, and 30 keV on three different crystal orientations (100), (110), and (111). At low energies (1.1 and 5 keV) σ0 depends on the crystalline orientation wheras at high energies (30 keV) no differentiation occurs. It is shown that the value of the second crossover energy E2, for which the intrinsic SEE yield σ0=1, is extremely delicate to measure with precision. It is about 15 keV±500 eV for the (100) orientation, 13.5 keV±500 eV for the (110), and 18.5 keV±500 eV for the (111) one. At low current density J⩽105 pA/cm2, the variation of σ with the injected dose makes possible the observation of a self-regulated regime characterized by a steady value of the SEE yield σst=1. At low energies 1.1 and 5 keV, there is no current density effects in MgO, but at high energies ≈30 keV, apparent current density effects come from a bad collect of secondary electrons, due to very high negative surface potential. At 30 keV energy, an intense erratic electron exoemission was observed on the MgO (110) orientation annealed at 1500 °C. This phenomenon is the result of a disruptive process similar to flashover, which takes place at the surface of the material.

  19. Calculation of electron-impact rotationally elastic total cross sections for NH{sub 3}, H{sub 2}S, and PH{sub 3} over the energy range from 0.01 eV to 2 keV

    SciTech Connect

    Limbachiya, Chetan; Vinodkumar, Minaxi; Mason, Nigel

    2011-04-15

    This paper report results of calculation of the total cross section Q{sub T} for electron impact on NH{sub 3}, H{sub 2}S, and PH{sub 3} over a wide range of incident energies from 0.01 eV to 2 keV. Total cross sections Q{sub T} (elastic plus electronic excitation) for incident energies below the ionization threshold of the target were calculated using the UK molecular R-matrix code through the Quantemol-N software package and cross sections at higher energies were derived using the spherical complex optical potential formalism. The two methods are found to give self-consistent values where they overlap. The present results are, in general, found to be in good agreement with previous experimental and theoretical results.

  20. Measurement of the mass attenuation coefficient from 81 keV to 1333 keV for elemental materials Al, Cu and Pb

    NASA Astrophysics Data System (ADS)

    Gjorgieva, Slavica; Barandovski, Lambe

    2016-03-01

    The mass attenuation coefficients (μ/ρ) for 3 high purity elemental materials Al, Cu and Pb were measured in the γ-ray energy range from 81 keV up to 1333 keV using 22Na, 60Co 133Ba and 133Cs as sources of gamma radiation. Well shielded detector (NaI (Tl) semiconductor detector) was used to measure the intensity of the transmitted beam. The measurements were made under condition of good geometry, assuring that any photon absorbed or deflected appreciably does not reach the detector. The measured values are compared with the theoretical ones obtained by Seltzer (1993).

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

    DOEpatents

    Wang, Ching L.

    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.

  2. Observations of 12-200 keV X-rays from GX 339-4

    NASA Technical Reports Server (NTRS)

    Nolan, P. L.; Gruber, D. E.; Knight, F. K.; Matteson, J. L.; Peterson, L. E.; Levine, A. M.; Lewin, W. H. G.; Primini, F. A.

    1982-01-01

    X-ray spectra of GX 339-4 measured on three occasions in 1977 and 1978 are presented. These are the first reported measurements above 10 keV. The spectra can be described as the superposition of a soft component, which is dominant below about 20 keV, and a hard component at higher energy. Simultaneous measurements at lower energy show that the soft component vanished during the observation in early 1978. The behavior of these two components is similar to that of the spectrum of Cygnus X-1; this reinforces the previously noted resemblance in rapid X-ray variability.

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

    SciTech Connect

    McNulty, I.; Feng, Y.P.; Hadda, W.S.; Trebes, J.E.

    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.

  4. 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.

  5. HEAO 3 upper limits to the expected 1634 KeV line from SS 483

    NASA Technical Reports Server (NTRS)

    Wheaton, W. A.; Ling, J. C.; Mahoney, W. A.; Jacobson, A. S.

    1985-01-01

    A model based on 24 Mg(1369) was developed as the source of the lines in which refractory grains in the jets, containing Mg and 0, are bombarded, by ambient protons in the local ISM. The narrowness of the features results because the recoil Mg nucleus is stopped in the grain before the 1369 keV excited state decays. A consequence of the 24 Mg interpretation is the expected appearance of other emission lines, due to 20 Ne and 20 Na, which are produced by proton bombardment of 24 Mg at the 33 MeV/nucleon energy corresponding to the velocity of the jets. These lines appear at rest energies of 1634 keV and 1636 keV, respectively, and should have essentially the same total flux as that emited at 1369 keV. The HEAO 3 data are examined to search for the 1634 keV (rest) emission. The observation and analysis, the results, and the implications for the understanding of SS 433 are discussed.

  6. Static and time-resolved 10-1000 keV x-ray imaging detector options for NIF

    SciTech Connect

    Landen, O.L.; Bell, P.M.; McDonald, J.W.; Park, H.-S.; Weber, F.; Moody, J.D.; Lowry, M.E.; Stewart, R.E.

    2004-10-01

    High energy (>10 keV) x-ray self-emission imaging and radiography will be essential components of many NIF high energy density physics experiments. In preparation for such experiments, we have evaluated the pros and cons of various static [x-ray film, bare charge-coupled device (CCD), and scintillator + CCD] and time-resolved (streaked and gated) 10-1000 keV detectors.

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

    NASA Technical Reports Server (NTRS)

    Morrison, R.; Mccammon, D.

    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.

  8. Precision Measurements of the 278 keV {sup 14}N(p,{gamma}) and the 151 keV {sup 18}O(p,{alpha}) Resonance Parameters

    SciTech Connect

    Borowski, M.; Lieb, K. P.; Uhrmacher, M.; Bolse, W.

    2009-01-28

    In thin film technology, analytical methods for monitoring the deposition of oxide and nitride coatings and the effects of corrosive, laser and ion-beam treatments have attracted considerable attention. For depth-profiling the concentrations of light isotopes, resonant nuclear reaction analysis is an excellent non-destructive ion-beam analytical tool. We report here on precision measurements of the 278 keV {sup 14}N(p,{gamma}) and the 151 keV {sup 18}O(p,{alpha}) resonances using the high-resolution proton beam of the Goettingen IONAS accelerator. The deduced resonance energies E{sub R} and total widths {gamma}(in the laboratory system) are E{sub R} = 277.60(27) keV and {gamma} = 1115(33) eV for the {sup 14}N(p,{gamma}) resonance, and E{sub R} = 150.97(26) keV and {gamma} = 178(35) eV for the {sup 18}O(p,{alpha}) resonance. These values are significantly more precise than the ones quoted in the literature.

  9. Spatial distribution of upstream magnetospheric geq50 keV ions

    NASA Astrophysics Data System (ADS)

    Anagnostopoulos, G. C.; Argyropoulos, G.; Kaliabetsos, G.

    2000-01-01

    We present for the first time a statistical study of geq50 keV ion events of a magnetospheric origin upstream from Earth's bow shock. The statistical analysis of the 50-220 keV ion events observed by the IMP-8 spacecraft shows: (1) a dawn-dusk asymmetry in ion distributions, with most events and lower intensities upstream from the quasi-parallel pre-dawn side (4 LT-6 LT) of the bow shock, (2) highest ion fluxes upstream from the nose/dusk side of the bow shock under an almost radial interplanetary magnetic field (IMF) configuration, and (3) a positive correlation of the ion intensities with the solar wind speed and the index of geomagnetic index Kp, with an average solar wind speed as high as 620 km s-1 and values of the index Kp > 2. The statistical results are consistent with (1) preferential leakage of sim50 keV magnetospheric ions from the dusk magnetopause, (2) nearly scatter free motion of sim50 keV ions within the magnetosheath, and (3) final escape of magnetospheric ions from the quasi-parallel dawn side of the bow shock. An additional statistical analysis of higher energy (290-500 keV) upstream ion events also shows a dawn-dusk asymmetry in the occurrence frequency of these events, with the occurrence frequency ranging between sim16%-sim34% in the upstream region.

  10. Preparation for B4C/Mo2C multilayer deposition of alternate multilayer gratings with high efficiency in the 0.5-2.5 keV energy range

    NASA Astrophysics Data System (ADS)

    Choueikani, Fadi; Delmotte, Franck; Bridou, Françoise; Lagarde, Bruno; Mercere, Pascal; Otero, Edwige; Ohresser, Philippe; Polack, François

    2013-03-01

    This paper presents a study of B4C/Mo2C multilayers mirrors with the aim of using it in the achievement of Alternate MultiLayer (AML) grating. Such component allows a high efficiency in the 500-2500 eV energy range for the DEIMOS beamline. Multilayers were deposited on silicon substrate. They are characterized by reflectometry under grazing incidence. Numerical adjustments were performed with a model of two layers in the period without any interfacial. A prototype of AML grating was fabricated and characterized. The efficiency of the first order of diffraction was worth 15% at 1700 eV.

  11. Secondary ion emission from V and Al surfaces under keV light ion on bombardment

    NASA Astrophysics Data System (ADS)

    Blauner, Patricia G.; Weller, Martha R.; Kaurin, Michael G.; Weller, Robert A.

    1986-03-01

    Positive secondary ion mass spectra have been measured for oxidized polycrystalline V and Al targets bombarded by H +, H 2+, He + and Ar + ions with beam energies ranging from 25 keV to 275 keV. An enhancement in the relative yield of positive ions of electronegative surface constituents, in particular O + is observed under light ion bombardment. Metallic ion intensities were found to decrease with increasing primary beam energy in proportion to the estimated total sputtering yields for these targets and beams. In contrast, the O + secondary ion intensities were independent of primary beam energy. This behavior is similar to that observed previously with heavy ions of comparable velocities. In addition, for the projectiles and targets used in these measurements, no energy thresholds or collective effects were observed in the emission of any positive ion. Published data on secondary ion emission resulting from electron, photon, and heavy ion bombardment are compared with these results.

  12. 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.

  13. The Solar Flare 4: 10 keV X-ray Spectrum

    NASA Technical Reports Server (NTRS)

    Phillips, K. J. H.

    2004-01-01

    The 4-10 keV solar flare spectrum includes highly excited lines of stripped Ca, Fe, and Ni ions as well as a continuum steeply falling with energy. Groups of lines at approximately 7 keV and approximately 8 keV, observed during flares by the broad-band RHESSI spectrometer and called here the Fe-line and Fe/Ni-line features, are formed mostly of Fe lines but with Ni lines contributing to the approximately 8 keV feature. Possible temperature indicators of these line features are discussed - the peak or centroid energies of the Fe-line feature, the line ratio of the Fe-line to the Fe/Ni-line features, and the equivalent width of the Fe-line feature. The equivalent width is by far the most sensitive to temperature. However, results will be confused if, as is commonly believed, the abundance of Fe varies from flare to flare, even during the course of a single flare. With temperature determined from the thermal continuum, the Fe-line feature becomes a diagnostic of the Fe abundance in flare plasmas. These results are of interest for other hot plasmas in coronal ionization equilibrium such as stellar flare plasmas, hot gas in galaxies, and older supernova remnants.

  14. Physics of a 17 keV neutrino.

    NASA Astrophysics Data System (ADS)

    Kayser, B.

    The possible 17 keV neutrino, if real, cannot be νμ but could be essentially ντ. Relic 17 keV neutrinos from the big bang must have disappeared, through a non-Standard-Model decay or annihilation process, before the present epoch. If one assumes that the 17 keV neutrino is not a Dirac neutrino of the conventional kind, then one is led to picture it as a Dirac neutrino of the unconventional Zeldovich-Konopinski-Mahmoud kind. It is then an amalgam of ντ and ν¯μ.

  15. Spectral Analysis on Solar Flares with an Emission > 300 keV

    NASA Astrophysics Data System (ADS)

    Vargas, R.; Connaughton, V.

    2013-12-01

    The continuum gamma-ray emission from solar flares is caused when a population of electrons is accelerated to relativistic speeds and interacts with the solar plasma. However, it has been theorized that the gamma-ray emission from some brighter flares comes from two populations of electrons. Using the Gamma-Ray Burst Monitor (GBM), we studied the gamma-ray emission spectra of solar flares and paid special attention to the solar flares that showed emission above 300 keV. We found that the emission above 300 keV was better fit with a broken power-law than a single power-law, evidence that the gamma-ray emission from certain solar flares involved two populations of electrons. Specifically, our best model involved a broken power law that had a steeper slope before the break in energy than after. We studied the spectral parameters as a function of time during the period of the high-energy emission. We also found that solar flares with emission above 300 keV form a small subset (~4%) of flares that trigger GBM above 20 keV. One of the flares with an emission greater than 300 keV was fitted with a Broken Power Law model. Only data from the BGO detector was used in making the plots. Various parameters of the fit have been plotted vs. time with the top two graphs representing the light curves of the flare from different detectors (BGO-0 and NaI-4). A spectral fit for bn100612038 for the time interval of [45s-50s] using only the BGO (0) detector file. Data from this fit was used in creating the other plots.

  16. 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.; Gladstone, G. R.; Waite, J. H.; Cravens, T.; Ford, P.

    2007-01-01

    The discovery in XMM-Newton X-ray data of X-ray emission above 2 keY 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.

  17. The diffuse X-ray spectrum from 14-200 keV as measured on OSO-5

    NASA Technical Reports Server (NTRS)

    Dennis, B. R.; Suri, A. N.; Frost, K. J.

    1973-01-01

    The measurement of energy spectrum of the diffuse component of cosmic X-ray flux made on the OSO-5 spacecraft is described. The contributions to the total counting rate of the actively shielded X-ray detector are considered in some detail and the techniques used to eliminate the non-cosmic components are described. Positive values for the cosmic flux are obtained in seven energy channels between 14 and 200 keV and two upper limits are obtained between 200 and 254 keV. The results can be fitted by a power law spectrum. A critical comparison is made with the OSO-3 results. Conclusions show that the reported break in the energy spectrum at 40 keV is probably produced by an erroneous correction for the radioactivity induced in the detector on each passage through the intense charged particle fluxes in the South Atlantic anomaly.

  18. Calibration of SIOM-5FW film in the range of 0.1-4 keV

    NASA Astrophysics Data System (ADS)

    Chenais-Popovics, C.; Reverdin, C.; Ioannou, I.

    2006-06-01

    The SIOM-5FW film produced for the sub-keV x-ray detection range was calibrated here in a wide energy range (0.1-4keV). A single set of parameters valid in the whole measured energy range was determined for the calibration of the Shangai 5F (SIOM-5FW) film from a parametric fit of the data. The sensitivity of the SIOM-5FW film was measured to be four times lower than that of the Kodak DEF film at 2.5keV photon energy. Modeling of the DEF and SIOM-5FW films provides a good comparison of their sensitivity in the 0.1-10keV range.

  19. Calibration of SIOM-5FW film in the range of 0.1-4 keV

    SciTech Connect

    Chenais-Popovics, C.; Reverdin, C.; Ioannou, I.

    2006-06-15

    The SIOM-5FW film produced for the sub-keV x-ray detection range was calibrated here in a wide energy range (0.1-4 keV). A single set of parameters valid in the whole measured energy range was determined for the calibration of the Shangai 5F (SIOM-5FW) film from a parametric fit of the data. The sensitivity of the SIOM-5FW film was measured to be four times lower than that of the Kodak DEF film at 2.5 keV photon energy. Modeling of the DEF and SIOM-5FW films provides a good comparison of their sensitivity in the 0.1-10 keV range.

  20. Study of photon attenuation coefficients of some multielement materials. [123-1250 keV

    SciTech Connect

    Bhandal, G.S. ); Singh, K. . Dept. of Physics)

    1994-03-01

    Total photon mass attenuation of six multielement shielding materials (concrete, plaster of paris, quick lime, black cement, white cement, and silica) is measured in the 123- to 1,250-keV energy range. The experimental results are analyzed in terms of cross sections, effective atomic numbers, and electron densities. Considerable sensitivity of the total mass attenuation coefficients and effective atomic numbers to variations in oxygen content are found in these multielement materials.

  1. Compton polarimeter for 10–30 keV x rays

    SciTech Connect

    Weber, S.; Beilmann, C.; Shah, C.; Tashenov, S.

    2015-09-15

    We present a simple and versatile polarimeter for x rays in the energy range of 10–30 keV. It uses Compton scattering in low-Z materials such as beryllium or boron carbide. The azimuthal distribution of the scattered x rays is sampled by an array of 12 silicon PIN diodes operated at room temperature. We evaluated the polarimetry performance using Monte-Carlo simulations and show experimental results.

  2. Compton polarimeter for 10-30 keV x rays.

    PubMed

    Weber, S; Beilmann, C; Shah, C; Tashenov, S

    2015-09-01

    We present a simple and versatile polarimeter for x rays in the energy range of 10-30 keV. It uses Compton scattering in low-Z materials such as beryllium or boron carbide. The azimuthal distribution of the scattered x rays is sampled by an array of 12 silicon PIN diodes operated at room temperature. We evaluated the polarimetry performance using Monte-Carlo simulations and show experimental results. PMID:26429432

  3. Resolution of the 1,238-keV gamma-ray line from supernova 1987A

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.; Barthelmy, S. D.; Gehrels, N.; Tueller, J.; Leventhal, M.

    1989-01-01

    Observations of supernova 1987A from the maiden flight of the Gamma-Ray Imaging Spectrometer (GRIS) are reported. SN1987A was observed for a period of 11.1 hours on May 1, 1988. Line emission at 1238 keV and continuum emission from 60-800 keV were detected. A gaussian line profile gives an acceptable fit to the 1238 keV line. The best-fit parameters are: flux = 8.5(+ 2.3, - 2.2) x 10 to the -4th photons/sq cm/s; peak energy = 1235.4 (+ 2.2, - 2.4) keV; FWHM = 16.3 (+ 6.1, - 5.7) keV. No evidence is found for a supernova-produced red- or blueshift in the 1238 keV line. The measured linewidth is a factor of about two greater than model predictions, although the discrepancy represents only two standard deviations. The line profiles are characteristic of optically thin regions, whereas the intensity implies a mean optical depth of about two. Fragmentation or nonspherical geometry of the supernova shell are possible explanations of the data.

  4. Solar wind ˜0.1-1.5 keV electrons at quiet times

    NASA Astrophysics Data System (ADS)

    Tao, Jiawei; Wang, Linghua; Zong, Qiugang; Li, Gang; Salem, Chadi S.; Wimmer-Schweingruber, Robert F.; He, Jiansen; Tu, Chuanyi; Bale, Stuart D.

    2016-03-01

    We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 3-D Plasma & Energetic Particle (3DP) instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. Firstly, we separate strahl (beaming) electrons and halo (isotropic) electrons based on their features in pitch angle distributions. Secondly, we fit the observed energy spectrum of both the strahl and halo electrons at ˜0.1-1.5 keV to a Kappa distribution function with an index κ, effective temperature Teff and density n0. We also integrate the the measurements over ˜0.1-1.5 keV to obtain the average electron energy Eavg of the strahl and halo. We find a strong positive correlation between κ and Teff for both the strahl and halo, possibly reflecting the nature of the generation of these suprathermal electrons. Among the 245 selected samples, ˜68% have the halo κ smaller than the strahl κ, while ˜50% have the halo Eh larger than the strahl Es.

  5. New Observations of Soft X-ray (0.5-5 keV) Solar Spectra

    NASA Astrophysics Data System (ADS)

    Caspi, A.; Woods, T. N.; Mason, J. P.; Jones, A. R.; Warren, H. P.

    2013-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable on many time scales. However, the actual solar soft X-ray (SXR) (0.5-5 keV) spectrum is not well known, particularly during solar quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include high-resolution but very narrow-band spectra from crystal spectrometers (e.g., Yohkoh/BCS), or integrated broadband irradiances from photometers (e.g., GOES/XRS, TIMED/XPS, etc.) that lack detailed spectral information. In recent years, broadband measurements with moderate energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and SAX on MESSENGER, although they did not extend to energies below ~1 keV. We present observations of solar SXR emission obtained using new instrumentation flown on recent SDO/EVE calibration rocket underflights. The photon-counting spectrometer, a commercial Amptek X123 with a silicon drift detector and an 8 μm Be window, measures the solar disk-integrated SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution and 1 s cadence. A novel imager, a pinhole X-ray camera using a cooled frame-transfer CCD (15 μm pixel pitch), Ti/Al/C filter, and 5000 line/mm Au transmission grating, images the full Sun in multiple spectral orders from ~0.1 to ~5 nm with ~10 arcsec/pixel and ~0.01 nm/pixel spatial and spectral detector scales, respectively, and 10 s cadence. These instruments are prototypes for future CubeSat missions currently being developed. We present new results of solar observations on 04 October 2013 (NASA sounding rocket 36.290). We compare with previous results from 23 June 2012 (NASA sounding rocket 36.286), during which solar activity was low and no signal was observed above ~4 keV. We compare our spectral and imaging measurements with spectra and broadband irradiances from other instruments, including SDO/EVE, GOES/XRS, TIMED

  6. Compact, maintainable 80-KeV neutral beam module

    DOEpatents

    Fink, Joel H.; Molvik, Arthur W.

    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.

  7. 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.

  8. Evaluation of 238U Resonance Parameters from 0 to 20 keV

    NASA Astrophysics Data System (ADS)

    Derrien, H.; Courcelle, A.; Leal, L. C.; Larson, N.; Santamarina, A.

    2005-05-01

    The neutron resonance parameters of 238U were obtained in the energy range 0 to 20 keV from a sequential SAMMY analysis of the most recent high-resolution neutron transmission and neutron capture cross-section measurements. Special care was taken in the analysis of the lowest s-wave resonances leading to resonance parameters slightly different from those of ENDF/B-VI (Moxon-Sowerby resonance parameters). The resolved-resonance range was extended to 20 keV, taking advantage of the high-resolution neutron transmission data of Harvey and neutron capture data of Macklin et al. Preliminary integral tests were performed with the new resonance parameters; thermal low-enriched benchmark calculations show an improvement of the keff prediction, mainly due to a 1.5% decrease of the capture cross section at 0.0253 eV and about a 0.4% decrease of the effective shielded resonance capture integral.

  9. A 24 keV liquid-metal-jet x-ray source for biomedical applications

    SciTech Connect

    Larsson, D. H.; Takman, P. A. C.; Lundstroem, U.; Burvall, A.; Hertz, H. M.

    2011-12-15

    We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30-70 W electron beam is magnetically focused onto the jet, producing a circular 7-13 {mu}m full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In K{sub {alpha}} line is 3 x 10{sup 9} photons/(s x mm{sup 2}x mrad{sup 2}x 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

  10. Evaluation of 238U Resonance Parameters from 0 to 20 keV

    SciTech Connect

    Derrien, H.; Leal, L.C.; Larson, N.; Courcelle, A.; Santamarina, A.

    2005-05-24

    The neutron resonance parameters of 238U were obtained in the energy range 0 to 20 keV from a sequential SAMMY analysis of the most recent high-resolution neutron transmission and neutron capture cross-section measurements. Special care was taken in the analysis of the lowest s-wave resonances leading to resonance parameters slightly different from those of ENDF/B-VI (Moxon-Sowerby resonance parameters). The resolved-resonance range was extended to 20 keV, taking advantage of the high-resolution neutron transmission data of Harvey and neutron capture data of Macklin et al. Preliminary integral tests were performed with the new resonance parameters; thermal low-enriched benchmark calculations show an improvement of the keff prediction, mainly due to a 1.5% decrease of the capture cross section at 0.0253 eV and about a 0.4% decrease of the effective shielded resonance capture integral.