WorldWideScience

Sample records for 5-100 kev range

  1. INTEGRAL observations of the cosmic X-ray background in the 5-100 keV range via occultation by the Earth

    Churazov, E.; Sunyaev, R.; Revnivtsev, M.;

    2007-01-01

    due to occultation of extragalactic objects by the Earth disk was used to obtain the spectrum of the Cosmic X-ray Background ( CXB). Various sources of contamination were evaluated, including compact sources, Galactic Ridge emission, CXB reflection by the Earth atmosphere, cosmic ray induced emission...... by the Earth atmosphere and the Earth auroral emission. Results. The spectrum of the cosmic X-ray background in the energy band 5-100 keV is obtained. The shape of the spectrum is consistent with that obtained previously by the HEAO-1 observatory, while the normalization is similar to 10% higher...

  2. Attosecond quantum entanglement in neutron Compton scattering from water in the keV range

    Scattering of neutrons in the 24-150keV incident energy range from H2O relative to that of D2O and H2O-D2O mixtures was reported very recently. Studying time-of-flight integrated intensities, the applied experimental procedure appears to be transparent and may open up a novel class of neutron experiments regarding the 'anomalous' scattering from protons, firstly observed in our experiment at ISIS in the 5-100eV range. The keV-results were analyzed within standard theory, also including (1) multiple scattering and (2) the strong incident-energy dependence of the neutron-proton cross-section σH(E0) in this energy range. The analysis reveals a striking anomalous ratio of scattering intensity of H2O relative to that of D2O of about 20%, thus being in surprisingly good agreement with the earlier results of the original experiment at ISIS

  3. The Range of 1-3 keV Electrons in Solid Oxygen and Carbon Monoxide

    Oehlenschlæger, M.; Andersen, H.H.; Schou, Jørgen; Sørensen, H.

    The range of 1-3 keV electrons in films of solid oxygen and carbon monoxide has been measured by a mirror substrate method. The technique used here is identical to the one previously used for range measurements in solid hydrogen and nitrogen. The range in oxygen is slightly shorter than that in...... nitrogen whereas the range in carbon monoxide is about 20% larger than that in the nitrogen....

  4. The range of 1-3 keV electrons in solid oxygen and carbon monoxide

    The range of 1-3 keV electrons in films of solid oxygen and carbon monoxide has been measured by a mirror-substrate method. The technique used here is identical to the one previously used for range measurements on solid hydrogen and nitrogen. The range in oxygen is slightly shorter than that in nitrogen whereas the range in carbon monoxide is about 20% larger than that in the nitrogen. (orig.)

  5. The Range of 1-3 keV Electrons in Solid Oxygen and Carbon Monoxide

    Oehlenschlæger, M.; Andersen, H.H.; Schou, Jørgen;

    1985-01-01

    The range of 1-3 keV electrons in films of solid oxygen and carbon monoxide has been measured by a mirror substrate method. The technique used here is identical to the one previously used for range measurements in solid hydrogen and nitrogen. The range in oxygen is slightly shorter than that in...... nitrogen whereas the range in carbon monoxide is about 20% larger than that in the nitrogen....

  6. Photon interaction measurements of certain compounds in the energy range 30-660 keV

    The total photon interaction cross sections at six energies in the energy range 30-660 keV are determined in ten compounds, (NaNO3, KNO3, Sr(NO3)2, NaCl, SrCl2-2H2), NaClO3, (NH4)SO4, MgSO4) using a NaI(Tl) scintillation spectrometer in a good geometry setup. Analysis of the experimental data in terms of cross sections and effective atomic numbers is presented

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

    Moldovan, G., E-mail: grigore.moldovan@materials.ox.ac.uk [University of Oxford, Department of Materials, Parks Road, Oxford OX1 3PH (United Kingdom); Sikharulidze, I. [Leiden University, Leiden Institute of Chemistry, P.O. Box 9502, 2300RA Leiden (Netherlands); Matheson, J.; Derbyshire, G. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX (United Kingdom); Kirkland, A.I. [University of Oxford, Department of Materials, Parks Road, Oxford OX1 3PH (United Kingdom); Abrahams, J.P. [Leiden University, Leiden Institute of Chemistry, P.O. Box 9502, 2300RA Leiden (Netherlands)

    2012-07-21

    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.

  8. Inelastic processes in K^(+)- He collisions in energy range 0.7 - 10 keV

    Lomsadze, R A; Kezerashvili, R Ya; Mosulishvili, N O; Phaneuf, R

    2013-01-01

    Absolute cross sections for charge exchange, ionization, stripping and excitation in K^(+) - He collisions were measured in the ion energy range 0.7 - 10 keV. The experimental data and the schematic correlation diagrams are used to analyze and determine the mechanisms for these processes. The increase of the excitation probability of inelastic channels with the angle of scattering is revealed. An exceptionally highly excited state of He is observed and a peculiarity for the excitation function of the resonance line is explained. The intensity ratio for the excitation of the K II \\lambda = 60.1 nm and \\lambda = 61.2 nm lines is 5:1 which indicates the high probability for excitation of the singlet resonance level $^{1}$P$_{1}$ compared to the triplet level $^{3}$P$_{1}$. The similarity of the population of the 4p state of the potassium ion and atom as well as the anomalously small values of the excitation cross sections are explained.

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

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

  10. 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

    The average 235U 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

  11. 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

    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.

  12. 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

    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.

  13. Energy dependence of some neutron dosimeter sensitivities in the 1 ev up to 4 kev energy range

    The sensitivities of DN-A-1 device and SNM-14 slow neutron counter with a combined moderator in the 1 eV up to 4 keV energy range has been experimentally determined. The IBR-30 reactor served as a neutron source, spectral distribution was performed by the time-of-flight method. The sensitivity constancy of a long counter in the 1 eV up to 4 keV energy range has been experimentally shown. The obtained sensitivity values and other data available could be used in determining energy dependencies of the device sensitivity in essential neutron energy range. It permits to evaluate their errors when using as dosimeters in radiation fields of nuclear physics installations

  14. Positron and electron backscattering from elemental solids in the 1-10 keV energy range

    Electron and positron backscattering coefficients are analytically calculated for a number of selected atomic targets in the energy range 1-10 keV and for incident angles between 0 deg. and 80 deg. The dependence of the backscattering coefficient on the material, on the projectile primary energy and on the incidence angle has been examined and discussed. Our results are found to be in better agreement with experiment than earlier Monte Carlo simulations

  15. Measurement of Fission Cross-Sections for Neutrons of Energies in the Range 40-500 keV

    Measurements have been made of the fission cross-section of U233, U234 , U236, Np237, Pu239 and Pu241 at several neutron energies between 40 keV and 500 keV. Measurements in this energy range are of importance in reactor calculations especially in fast dilute systems where the neutron flux is high in the 10- 100-keV energy range. Recent measurements at this laboratory of the U235 fission cross-section gave absolute values slightly lower than previous data. The present series of measurements are made relative to the new values of the U235 fission cross-section using back-to-back ionization chambers. The fissile foils were assayed by α-assay, direct weighing and coulometry. Good agreement was obtained between these assays. The fission measurements have an estimated accuracy of between 1 % and.2% and,combined with the, error on the U235 fission cross-section,give a final error of about 3% in the fission cross-sections. The present results together with those of previous measurements are given, and the corrections for fission- fragment absorption, backgrounds and scattering are discussed. (author)

  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

    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. Range Measurements of keV Hydrogen Ions in Solid Oxygen and Carbon Monoxide

    Schou, Jørgen; Sørensen, H.; Andersen, H.H.;

    1984-01-01

    Ranges of 1.3–3.5 keV/atom hydrogen and deuterium molecular ions have been measured by a thin-film reflection method. The technique, used here for range measurements in solid oxygen and carbon monoxide targets, is identical to the one used previously for range measurements in hydrogen and nitrogen....... The main aim was to look for phase-effects, i.e. gas-solid differences in the stopping processes. While measured ranges in solid oxygen were in agreement with known gas data, the ranges in solid carbon monoxide were up to 50% larger than those calculated from gas-stopping data. The latter result...

  18. Range measurements of keV hydrogen ions in solid oxygen and carbon monoxide

    Ranges of 1.3-3.5 keV/atom hydrogen and deuterium molecular ions have been measured by a thin-film reflection method. The technique, used here for range measurements in solid oxygen and carbon monoxide targets, is identical to the one used previously for range measurements in hydrogen and nitrogen. The main aim was to look for phase-effects, i.e. gas-solid differences in the stopping processes. While measured ranges in solid oxygen were in agreement with known gas data, the ranges in solid carbon monoxide were up to 50% larger than those calculated from gas-stopping data. The latter result agrees with that previously found for solid nitrogen. (orig.)

  19. Measurement of neutron capture cross section of 75As in the energy range from 29 to 1100 keV

    The cross sections for the 75As(n,γ)76As reaction were measured relatively to that of 197Au in neutron energy range from 29 to 1100 keV, using the activation technique. Neutrons were produced via the 7Li(p,n)7Be and T(p,n)3He reactions with a 2.5 MV Van de Graaff accelerator at Sichuan University. The activities after irradiation were measured with a calibrated high resolution HPGe detector. The errors of the measurements are 6.7%-7.8%. The experiment results were compared with existing data

  20. Effective atomic number of human enamel and dentin within a photo energy range from 10 to 200 KeV

    The Z and μ/p were determined regarding the total and partial photon interactions within the biological materials of human enamel and dentin, within the low photon energy range from 10 to 200 keV, which is of medical interest in terms of radiology. The mass attenuation coefficients were calculated by means of WinXCOM. The Z for total and partial photon interactions in the biological materials of human enamel and dentin have been determined within a radiological low photon energy range from 10 to 200 keV. The total Z values presented a similar behavior in both the enamel and dentin. The Z values decreased 23% in the enamel and by 32% in the dentin in direct proportion to the increase energy levels. The Z for all partial processes increased slightly and in direct proportion to the increase in energy levels. The value for photoelectric interaction proved to be the highest, whereas the value for incoherent scattering was the lowest. The total Z becomes a contribution due these three partial processes at any energy level. The value of the Z is quite sensitive to the weight fractions of the elements and the applied interpolation method. Concerning the importance of Z values to medical dosimetry, it is expected that the new data regarding Z values presented here in will be useful, particularly as regards the energy range of interest. (author)

  1. Characterisation of a detector based on microchannel plates for electrons in the energy range 10-20 keV

    Moldovan, G. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxon OX1 3PH (United Kingdom)], E-mail: grigore.moldovan@materials.ox.ac.uk; Matheson, J.; Derbyshire, G. [Rutherford Appleton Laboratory, Science and Technology Facilities Council, Chilton, Didcot, Oxon OX11 0QX (United Kingdom); Kirkland, A. [Department of Materials, University of Oxford, Parks Road, Oxford, Oxon OX1 3PH (United Kingdom)

    2008-11-11

    As part of a feasibility study into the use of novel electron detectors for an X-ray photoelectron emission microscope (XPEEM), we have characterised a detector based on microchannel plates (MCPs), a phosphor screen and a CCD camera. For XPEEM, an imaging detector is required for electrons in the energy range 10-20 keV. This type of detector is a standard fitment on commercial instruments and we have studied its performance in some detail in order to provide a baseline against which to evaluate future detector technologies. We present detective quantum efficiency (DQE), noise power spectrum (NPS) and modulation transfer function (MTF) measurements of a commercial detector, in the energy range of interest, as a function of the detector bias voltage.

  2. Search for galactic sources and bursts of x radiation in the 40-290 keV energy range with a spectrometer of the Kosmos-428 satellite

    Stationary sources and bursts of X-radiation in the 40-290 keV energy range have been found in the cetus constellation as a result of observations carried out with a spectrometer of the ''Kosmos-3428'' satellite

  3. Simulation of electron tracks in the energy range of 0.01 to 10 keV in water vapour

    The primary aim of this study was to develop a numerical program for simulating electron traces in steam for the energy range of 0.01 to 10 keV, and to prove the quality of the simulation by comparing calculations with measurements from current literature. Moreover, the application range of the program was to be shown by means of practical examples. The task could be performed by applying the Platzman method for analyzing experimental data with respect to their necessary consistency with established theoretical knowledge. The differential oscillator strength distribution, major differential ionization cross-sections and cross-sections for excitation and elastic collision were derived. By comparing major integral factors (e.g., W value (Co80)) with calculated results, it was possible to determine, e.g., the secondary electron cross-sections with the help of consistency tests. These derived activation cross-sections were used as the core of a Monte Carlo calculation programme (MOCA 87) for simulating electron trace structures which were evaluated in such a way that various calculation values could be compared critically with values obtained experimentally (e.g., for yields, depth and radial dose curves, micro-dosimetric distribution). On the whole, the programme exhibited sufficient consistency. (orig./HP)

  4. High-accuracy determination of the relative full energy peak efficiency curve of a coaxial HPGe detector in the energy range 700-1300 keV

    A method for the high-accuracy determination of the relative full energy peak efficiency is established. Radionuclides that emit at least two gamma-ray lines for which the relative intensity can be found (from the decay scheme) to much better than ±0.1% were used as calibration standards. Specifically, the 889 and 1120 keV lines of 46Sc, the 983 and 1312 keV lines of 48Sc, the 1173 and 1332 keV lines of 60Co, and the 702 and 871 keV lines of 94Nb were implemented. The high-accuracy calibration was taken to extend from the lowest line of 94Nb at 702 keV to the highest line of 60Co at 1332 keV. An analytical expression, based on linear least-squares fitting, was developed to describe the behavior of the relative efficiency curve in that energy range. As a result, the ability of predicting relative full energy peak efficiencies to within ±0.1% (over most of the energy range) was demonstrated. The presented method is applicable in any measurement that requires the minimum calibration bias in the determination of reaction rate ratios. Applications in neutron activation analysis (NAA) and in nuclear reactor dosimetry represent examples of such situations. (orig.)

  5. Simultaneous solution of Kompaneets equation and radiative transfer equation in the photon energy range 1-125 keV

    Radiative transfer equation in plane parallel geometry and Kompaneets equation is solved simultaneously to obtain theoretical spectrum of 1-125 keV photon energy range. Diffuse radiation field are calculated using time-independent radiative transfer equation in plane parallel geometry, which is developed using discrete space theory (DST) of radiative transfer in a homogeneous medium for different optical depths. We assumed free-free emission and absorption and emission due to electron gas to be operating in the medium. The three terms n, n2 and (∂n/∂xk) where n is photon phase density and xk=(hν/kTe), in Kompaneets equation and those due to free-free emission are utilized to calculate the change in the photon phase density in a hot electron gas. Two types of incident radiation are considered: (1) isotropic radiation with the modified black body radiation IMB and (2) anisotropic radiation which is angle dependent. The emergent radiation at τ=0 and reflected radiation τ=τmax are calculated by using the diffuse radiation from the medium. The emergent and reflected radiation contain the free-free emission and emission from the hot electron gas. Kompaneets equation gives the changes in photon phase densities in different types of media. Although the initial spectrum is angle dependent, the Kompaneets equation gives a spectrum which is angle independent after several Compton scattering times.

  6. Yield of chromosomal aberrations and recoil particle range in Chineses hamster fibroblasts exposed to 8.5 to 500 keV neutrons

    Induction of chromatid aberrations in S-phase Chinese hamster fibroblasts has been studied for irradiation by 60Co gamma rays and neutrons of average energy 8.5, 45, 83, 200 and 500 keV. At 10 per cent aberration level the relative biological afficiency varied between 2.2 +- 0.6 (at 8.5 keV) and a maximum of 47 +- 9 (at 200 keV). The neutron generated recoils have short range in comparison to chromosomal dimensions. The strong variation with neutron energy is therefore not necessarily reflecting variations in the average linear energy transfer. Good agreement between experimental and predicted response was obtained when effects ascribed to range were considered. A critical volume within which primary lesions should occur in order to make chromosomal aberrations probable was derived. The corresponding site radius was estimated to be 1-3 μm. (author)

  7. Calorimetry for dose measurement at electron accelerators in the 80-120 keV energy range

    Helt-Hansen, J.; Miller, A.; Duane, S.;

    2005-01-01

    Calorimeters for dose measurement at low-energy electron accelerator energies (80-120 keV) are described. Three calorimeters with different characteristics were designed and their dose response and measurement uncertainties were characterized. The heated air between the beam exit window and the c...

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

    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.

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

    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.

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

    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. copyright 1995 American Institute of Physics

  11. A compact flat-response x-ray detector for the radiation flux in the range from 1.6 keV to 4.4 keV

    A band-pass flat-response x-ray detector is designed to measure the absolute M-band x-ray flux. The detector comprises an x-ray diode and a compound filter that is carefully designed to achieve the desired response function in the range from 1.6 to 4.4 keV, i.e. the flatness of the spectral response is better than 5%. The designed response function is in excellent agreement with the calibrated one, indicating that the x-ray detector with various responses can be achieved with the state-of-art fabrication technique. (paper)

  12. Studies on the attenuation coefficients of some egyptian materials In the energy range 81-1332.5 KeV

    The linear and mass attenuation coefficients for different types of soil, sand and some building material samples at Inshas site in Egypt were investigated. The measurements were performed using gamma rays spectrometer consists of hyper pure germanium (HPGe) detector. The attenuation coefficients values were determined at the y-rays energies 81.0, 276.4, 302.8, 356.0 and 383.9 KeV of l33Ba, 661.7 KeV of 137Cs and 1173.4 and 1332.5 KeV of 60Co. The tested samples were dried, sieved to different particle sizes. The effect of cement to sand ratio on the attenuation coefficient values was studied. The results obtained showed that there was no specific relation between the mass attenuation coefficients and samples densities, but there was exponential decay relation between the mass attenuation coefficients and the gamma rays energy. There were variations of the values of the mass attenuation coefficients with the γ-rays energy. The obtained values for mass attenuation coefficients were compared with other values in different countries. These values agreed with some values and differed with others, because there are differences in the elemental components of each sample

  13. Measurement of attenuation cross-sections of some fatty acids in the energy range 122–1330 keV

    GAIKWAD D K; PAWAR P P

    2016-07-01

    The mass attenuation coefficients $(\\mu m)$ have been measured for undecylic acid (C$_{11}$H$_{22}$O$_2$), lauric acid (C$_{12}$H$_{24}$O$_2$), tridecylic acid (C$_{13}$H$_{26}$O$_2$), myristic acid (C$_{14}$H$_{28}$O$_2$), pentadecylic acid (C$_{15}$H$_{30}$O$_2$) andpalmitic acid (C$_{16}$H$_{32}$O$_2$) using $^{57}$Co, $^{133}$Ba, $^{137}$Cs, $^{60}$Co and $^{22}$Na emitted γ radiation with energies 122, 356,511, 662, 1170, 1275 and 1330 keV, respectively. The accurate values of the effective atomic number (Zeff), atomic cross-section $(\\sigma t,)$, electronic cross-section $(\\sigma e)$ and the effective electron density (Neff) have great significance in radiation protection and dosimetry. These quantities were obtained by utilizing experimentally measured values of mass attenuation coefficients $(\\mu m)$. A NaI(Tl) scintillation detector with 8.2% (at 662 keV) resolution was used for detecting of attenuated γ -photons. The variation in Zeff and Neff of fatty acids with energy is discussed. The experimental and theoretical results are in good agreement within 2% deviation.

  14. An improved long counter for neutron fluence measurement with a flat response over a wide energy range from 1 keV to 15 MeV

    A new long counter has been developed with a flat energy response over a wide range from 1 keV to 15 MeV. It consists of five 3He proportional counter tubes and a number of carefully designed polyethylene moderators. The structure of this detector was determined by careful Monte Carlo simulations. The calculated results show that the efficiency of this counter is uniform from 1 keV neutron energy to 15 MeV. Calibration was performed on an Am–Be source and the accelerator-produced monoenergetic D–D and D–T neutron sources. Fluctuation of the response curve is less than 10% over this energy range

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

    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.

  16. Search for galactic sources of X-ray bursts with scintillation spectrometers of the Kosmos-856 satellite in the energy range of 20-320 keV

    Search for galactic sources of X-pay bursts with a scintillation spectrometer of ''Kosmos-856'' satellite has given a negative result. During 21 hours of observations with two independent detectors not one burst of X-rays with the energy flux P 2x10-7 erg/cm2 has been found in the energy range 20-320 keV and duration 10s. This result disagrees with the data obtained with the ''Kosmos-428'' satellite

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

    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 γ-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 γ-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

  18. ESCA and REELS characterization of electrically conductive polyimide obtained by ion bombardment in the keV range

    Polyimide films were bombarded with Ar+ at 150 keV at various doses from 5 x 1012 to 2 x 1017 ions cm-2. Ion bombardment was found to produce a drastic decrease of the electrical resistivity of the polyimide from about 1016 to 3 x 10-3 Ω cm, the effect being dependent on the ion dose. The chemical structure of the conductive films obtained was characterized by means of ESCA and REELS techniques. The modification of the original polymer seems to proceed at low ion doses (up to 5 x 1014 ions cm-2) by means of the progressive elimination of the carbonyl groups and the related destruction of the imidic rings, while at high doses (from 5 x 1015) ions cm-2) the carbonization of the polyimide occurs with the production of an amorphous carbon still containing significant amount of residual N and O atoms. (author)

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

    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

  20. Construction, calibration and testing of a ionization chamber for exposure measurement of X and gamma rays in the energy range from 40 keV up to 1250KEV

    An unsealed thimble ionization chamber with connecting cable was designed, manufactured and tested at the IRD/CNEN, for exposure or exposure rate measurement of X or gamma rays in the energy range from 40 keV up to Cobalt-60. Recommendations given by IEC,TC-62(1974) were used as acceptance tests of the ionization chamber for use as a tertiary standard (field class instruments) in radiation therapy. In addition, intercomparison with commercially available chambers of reference class type were carried out in respect to field size dependence, energy dependence, short and long term stability.The results of those tests indicated the usefulness of the developed ionization chamber as a tertiary standard. (author)

  1. The Fano factor in gaseous xenon: A Monte Carlo calculation for X-rays in the 0.1 to 25 keV energy range

    A calculation of the Fano factor for gaseous xenon is carried out using a detailed Monte Carlo simulation of the absorption of X-rays in the 0.1 to 25 keV energy range. This factor is found to be energy dependent with values ranging from 0.17 to 0.32 and has sharp increases near the xenon absorption edges. An interpretation of the calculated results is made in terms of the relative importance of photoelectron and Auger/Coster-Kronig cascading electron processes. (orig.)

  2. Study on absolute sensitivity of X-ray electron-optical converter in the energy range of 7-20 keV

    Absolute spectral sensitivity of X-ray electron-optical converter (XREOC) with the beryllium window and a microchannel plate as a converting and amplifying element for the 7-20 keV X-ray range, was measured. Measurements were performed in the VEhPP-3M storage ring synchrotron radiation channel. It is shown that in the energy range indicated the ratio of photon number in the blue spectrum region at the XREOC outlet to the number of X-ray quanta at the inlet grows from 1200 up to 2200 photons per a quantum. Sensitivity change over the XREOC operating field is investigated

  3. Experimental determination of sensitivity of DN-A-1 dosimeter and 6LiJ(Eu) scintillation detector in sphere polyethylene moderators in the 30 keV neutron energy range

    DH-A-1 dosimeter and 6LiJ(Eu) detector, located in the center of polyethylene spheres with various diameters, were calibrated by means of neutrons with the energy of about 30 keV. The data on the detectors responses enable one to determine the shape of responses as a function of neutron energy more definitely at the energy range from some keV to some tens of keV. For DN-A-1 dosimeter response at neutrons and at neutrons in the energy range of about 30 keV the agreement is better than the uncertainties of measurements (about 20%)

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

    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

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

    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.

  6. Measurement of the U-236(n, f) cross section in the neutron energy range from 0.5 eV up to 25 keV

    Wagemans, Cyrillus; De Smet, Liesbeth; Vermote, Sofie; Heyse, Jan

    2008-01-01

    The U-236(n,f) cross section has been measured in the energy range from 0.5 eV to 25 keV at the Geel Electron Linear Accelerator neutron time-of-flight facility of the Institute for Reference Materials and Measurements in Geel, Belgium. A highly enriched U-236 sample was mounted back-to-back with a B-10 sample in the center of a Frisch-gridded ionization chamber, hence realizing a 2 pi detection geometry. A U-235(n,f) cross-section control measurement was performed in the same experimental co...

  7. Facilities and techniques for x-ray diagnostic calibration in the 100-eV to 100-keV energy range

    The Lawrence Livermore National Laboratory (LLNL) has been a pioneer in the field of x-ray diagnostic calibration for more than 20 years. We have built steady state x-ray sources capable of supplying fluorescent lines of high spectral purity in the 100-eV to 100-keV energy range, and these sources have been used in the calibration of x-ray detectors, mirrors, crystals, filters, and film. This paper discusses our calibration philosophy and techniques, and describes some of our x-ray sources. Examples of actual calibration data are presented as well

  8. Adjustment of a goniometer for X-rays optics calibration in the spectral range 1.5-20 KeV

    The aim of this memoir is the adjustment of a (θ, 2θ) goniometer coupled to X-rays source to calibrate mirrors (single layers like C, Ni, Au, etc... and multilayers like C/W, Si/W, etc...) in the spectral range 1.5 - 20 keV. For each kind of tested optics the adjustment of the goniometer include the procedure alignment of the different components (X-ray source, collimation slits, optics, detectors) and the first reflectivity measurements. Those measurements are compared those realized at LURE, using synchrotron radiation provided by SUPER ACO storage ring, and to a theoretical simulation

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

    Mirzoeva, I. K., E-mail: colombo2006@mail.ru [Russian Academy of Sciences, Space Research Institute (Russian Federation)

    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.

  10. A satellite-borne ion mass spectrometer for the energy range 0 to 16 keV

    The Ion Composition Experiment (ICE) on GEOS represents the first comprehensive attempt to measure the positive ion composition at high altitudes in the magnetosphere. Due to the heterogeneous nature of the magnetospheric plasma a novel mass spectrometer has been developed to cover the mass per charge range from 1H+ to beyond 138Ba+ and the energy per charge range from 0 to 16 keV/e. The ICE consists primarily of a cylindrical electrostatic analyzer followed by a curved analyzer incorporating crossed magnetic and electric fields. This combination has limited angular and energy focussing properties, but it maintains a mass resolution of about 4 over a wide range in energy and mass, sufficient for the objectives of measuring plasmas of both solar and terrestrial origin. High sensitivity and low background should allow measurements of rarer ion constituents, such as 3He2+ and 16O6+, down to flux levels of 10-2 ions (cm2 sec ster eV)-1. The unusually large mass range offers the possibility of identifying Li+ or Ba+ tracer ions which may be injected into the magnetosphere by active experiments. A sophisticated electronics combined with powerful ground computer and telecommand systems allow for very efficient scanning of the mass-energy space. Based on survey measurements a variety of special modes can be commanded, either manually or automatically by means of the ground station computer. (Auth.)

  11. 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

    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.

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

    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.

  13. Calibration of an UTW Si(Li) detector in the 0.28-22.1 keV energy range

    Uzonyi, I; Borbely-Kiss, I; Kiss, A Z

    2003-01-01

    The application of such detectors in the sub-keV region has been quite limited supposedly due to the lack of well-established calibration methods and the difficulties associated with their operation. The aim of this study has been twofold: first to check the applicability of the (micro)PIXE method for efficiency measurement of an UTW detector in the C K-Ag K subalpha energy region using thick targets, allowing a simple and low-cost solution for this problem; second: to test the new version of the PIXEKLM program down to the sub-keV range. (R.P.)

  14. Ranges, Reflection and Secondary Electron Emission for keV Hydrogen Ions Incident on Solid N2

    Børgesen, P.; Sørensen, H.; Hao-Ming, Chen

    1983-01-01

    Ranges were measured for 0.67–3.3 keV/amu hydrogen and deuterium ions in solid N2. Comparisons with similar results for N2-gas confirm the previously observed large phase effect in the stopping cross section. Measurements of the secondary electron emission coefficient for bulk solid N2 bombarded by...... 0.67–9 keV/amu ions also seem to support such a phase effect. It is argued that we may also extract information about the charge state of reflected projectiles....

  15. Influence of the PMMA slab and ISO water phantom in calibrating personal dosimeter in the energy range of 36-662 keV

    Personnel dosimeter calibration for the determination of operational quantities used in individual monitoring requires placement on a phantom that provides a reasonable approximation to the backscatter properties of the part of the body on which it is worn. The personal dose equivalent Hp(d) is defined in the human body which is not a measurable quantity. The reference International Commission on Radiation Units and Measurements (ICRU) tissue is not readily available; hence a phantom of alternative must be used for calibration. The well recognized polymethylmethacrylate (PMMA) slab phantom of size 30x30x15 cm3 are still being used in calibrating personal dosimeters. The International Organization for Standardization (ISO)-4037(3) has proposed another phantom of the same size as ICRU, which is named as ISO water phantom. In the present study, calibrated X-ray fields are characterized for National Institute of Advanced Industrial Science and Technology (AIST) middle beam spectrum series by which the influence of these proposed phantoms has been studied by the thermoluminescence dosimetry (TLD) technique. Discrepancies of responses within 8% have been observed at lower energies up to 42 keV. There is a very good agreement in responses is observed for ISO water slab and PMMA slab phantom for photon energies above 42 keV. Experimentally obtained correction factors for AIST radiation qualities of M50 and M60 for PMMA slab to ISO water phantom is proposed. Measured backscatter factor results from PMMA to ISO water-filled phantoms over the photon energy range 36 to 662 keV are reported. This shows that the new ISO water phantom is a better substitute of ICRU tissue phantom than the PMMA slab. (author)

  16. Inelastic processes in Na$^{+}-$Ne, Ar and Ne$^{+},$ Ar$^{+}-$Na collisions in energy range $0.5-14$ keV

    Lomsadze, R A; Kezerashvili, R Ya

    2015-01-01

    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 set-up. Ionization cross sections for Ne$^{+}-$Na and Ar$^{+}-$Na collisions are measured at the 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 collisi...

  17. Proposed experiments to detect keV range sterile neutrinos using energy-momentum reconstruction of beta decay or K-capture events

    Smith, Peter F

    2016-01-01

    Sterile neutrinos in the keV mass range may constitute the galactic dark matter. Various proposed direct detection and laboratory searches are reviewed. The most promising method in the near future is complete energy-momentum reconstruction of individual beta-decay or K-capture events, using atoms suspended in a magneto-optical trap. A survey of suitable isotopes is presented, together with the measurement precision required in a typical experimental configuration. It is concluded that among the most promising are the K-capture isotopes 131Cs, which requires measurement of an X-ray and several Auger electrons in addition to the atomic recoil, and 7Be which has only a single decay product but needs development work to achieve a trapped source. A number of background effects are discussed. It is concluded that sterile neutrinos with masses down to the 5-10 keV region would be detectable, together with relative couplings down to the level 10-10-10-11 in a 1-2 year running time.

  18. Contributions to the study of fast neutron spectrum in the 10 keV - 3 MeV range

    The main objective of the work presented in this thesis was to create a fast neutron spectrum corresponding to the conditions required for a reference neutron field. The reference system for the fast neutron dosimetry in reactors, which the author promoted, is referred to as ΣΣ-ITN in the books. The conditions for introducing the ΣΣ systems into the thermal columns have been determined. The original contribution consists in determining the Westcott parameters of reactions 151Eu(n,γ) 152Eu and 176Lu(n,γ) 17+H7Lu used as thermal spectrum factors. The neutron description of the spectrum in cavity ΣΣ revealed that it is a Maxwell thermal spectrum displaying a temperature of 305+-7 deg C and a very small epithermal component (phisub(epi)/phisub(thermal) =4,5.10-4). Better methods for determining reaction absolute rates resulted in less errors in calculating the microscopic integral sections mediated on the ΣΣ spectrum; there are under 5% errors for the fission cross sections and between 3% and 8% errors for the activating ones. The section values determined by the author have been included into the EXFOR library (IAEA); they are considered as reference measuremtns for the nuclear data improvement program. Testing the proposed method for the TRIGA on the ΣΣ-INT system proved that the multiple foil method provides correct results for both describing the spectral shape and for obtaining absolute values of the flux. Taking into account that the ΣΣ-ITN spectrum is a rapid one, the proposed method could not be tested within the low energy thermal and epithermal domain. For testing the method on an operational reactor, the core of the VVR-S IFIN reactor was employed. Due to the spectral structure of this reactor, it was possible to test the procedure within the whole energy range. In this view, the 5/10 core channel was selected which is similar to the channel required for measurements in the TRIGA-ROMANIA reactor. The absolute spectrum values are given in a

  19. Neutron-induced fission cross section of 237Np in the keV to MeV range at the CERN n_TOF facility

    Diakaki, M.; Karadimos, D.; Vlastou, R.; Kokkoris, M.; Demetriou, P.; Skordis, E.; Tsinganis, A.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviani, M.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; David, S.; Dolfini, R.; Domingo-Pardo, C.; Dorochenko, A.; Dridi, W.; Duran, I.; Eleftheriadis, Ch.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fuji, K.; Furman, W.; Goncalves, I.; Gallino, R.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Ioannidis, K.; Isaev, S.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karamanis, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Kolokolov, D.; Konovalov, V.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Massimi, C.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Sedysheva, M.; Stamoulis, K.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Voss, F.; Wendler, H.; Wiescher, M.; Wisshak, K.; n TOF Collaboration

    2016-03-01

    The neutron-induced fission cross section of 237Np was experimentally determined at the high-resolution and high-intensity facility n_TOF, at CERN, in the energy range 100 keV to 9 MeV, using the 235U(n ,f ) and 238U(n ,f ) cross section standards below and above 2 MeV, respectively. A fast ionization chamber was used in order to detect the fission fragments from the reactions and the targets were characterized as far as their mass and homogeneity are concerned by means of α spectroscopy and Rutherford backscattering spectroscopy respectively. Theoretical calculations within the Hauser-Feshbach formalism have been performed, employing the empire code, and the model parameters were tuned in order to successfully reproduce the experimental fission cross-sectional data and simultaneously all the competing reaction channels.

  20. Contribution to time resolved X-ray fluence and differential spectra measurement method improvement in 5-200 KeV range. Application to pulsed emission sources

    Two types of sensors have been developed to measure locally the time-resolved fluence and differential energetic spectrum of pulsed X-ray in the energy range 5 to 200 keV. Rise time of these sensors is very short (10 ns) in order to permit time-resolved measurements. Fluence sensors have been developed by putting filters in front of detector in order to make sensor response independent of X-ray energy and proportional to X-ray fluence. The energetic differential spectrum was calculated by way of a method similar to the ROSS method but using filters separated within a pair defining adjacent spectral width. A detailed analysis of uncertainties affecting calculated fluence and spectrum has been done

  1. Energy dependence of some neutron detector sensitivity in the energy range from 17 keV up to 1 MeV

    The results of experimental determination of sensitivity of neutron detectors used as dosimeters in the energy range from 17 keV to 1 MeV are presented. The measurements were performed in the EhG-2.5 accelerator. Monoenergetic neutrons were produced in the T (p, n)3He reaction at different proton energies. The detectors were placed at angles from 30 deg to 120 deg to proton beam direction. The detector sensitivity was evaluated by comparison of their values with those of the OVC-3M standard neutron counter. The obtained results could be used for determining energy dependences of sensitivities of detectors under study and for evaluating the errors of measurements of neutron doses in the radiation fields behind nuclear-physical installation shielding

  2. Scintillation spectrometers of the Kosmos-856 and Kosmos-914 satellites for studies of galactic x-rays in the energy range of 20-320 keV

    Scintillation spectrometers used in the studies of space hard X-rays in the energy range of 20-300 keV on the ''Kosmos-856'' and ''Kosmos-914'' satellites are described. A combined scintillation detector, consisting of NaI(Tl) (the height is 10 mm) and CsI(Tl) (the height is 35 mm), has been used in each of the spectrometers. The diameter of each scintillating crystal is 80 mm. A crystal of NaI(Tl) is used as a spectotrometric crystal. A crystal of CsI(Tl) is used as an active shield for the NaI(Tl) crystal To exclude recording of charged particles the detector is surrounded with a plastic scintillator. The use of a combined scintillation detector allowed to decrease the background considerably and thus to increase significantly the sensitivity of the instrument in comparison with the similar spectrometer which was used in the ''Kosmos-428'' satellite

  3. Investigation of Methanol Formation Mechanisms in H2O+CH4 Ices Subjected to 5 keV Electrons at a 10-100 K Temperature Range

    Stelmach, K. B.; Cooper, P. D.

    2014-12-01

    Methane (CH4) and water are one of the most common molecules in both planetary bodies and interstellar dust grains. Another common molecule, methanol (CH3OH), is thought to form in CH4+H2O ices. However, the exact formation mechanisms of methanol from cosmic rays are not well known, especially in the temperatures of interest. Experiments were performed using high energy electrons (5 keV) to irradiate mixtures of 1:10, 1:5, and 1:3 CH4+H2O ices under a temperature range of 10-100 Kelvin with Fourier Transform Infrared (FTIR) spectroscopy being used to identify the products. Isotopologues of the two molecules (D2O and CD4) were used to probe for the mechanisms. Other products were formed as well and their potential mechanisms are identified. The implications of the mechanisms for planetary and interstellar chemistry are discussed.

  4. Electron-transfer reactions of fast Xe/sup n/+ ions with Xe in the energy range 15 keV to 1.6 MeV

    Electron-transfer cross sections for the reactions of Xe/sup n/+ (n = 1--4) with Xe atoms have been determined as a function of projectile-ion kinetic energy in the range 15 keV--1.6 MeV. For Xe/sup n/+ (n = 2, 3, 4), cross sections for sequential transfer of two or more electrons in single-ion--atom collisions have been obtained. These cross sections decrease with increasing number of electrons transferred. The observed insensitivity of cross sections to projectile kinetic energy in the range investigated follows the condition that the linear velocity of the ion is less than the orbital velocity of a valence electron in the slow-moving target atom. Attenuation cross sections for reactions of Xe/sup n/+ (n = 2, 3, 4) follow approximately a Z2/sub direct-sum/ charge dependence. A simple classical model based on Coulomb forces yields cross sections with a reasonable fit to the experimental data

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

    Legere, J S; Macri, J R; McConnell, M L; Narita, T; Ryan, J M

    2005-01-01

    This paper discusses the latest progress in the development of GRAPE (Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The purpose of GRAPE is to measure the polarization of hard X-rays in the 50-300 keV energy range. We are particularly interested in X-rays that are emitted from solar flares and gamma-ray bursts (GRBs). Accurately measuring the polarization of the emitted radiation from these sources will lead, to a better understating of both the emission mechanisms and source geometries. The GRAPE design consists of an array of plastic scintillators surrounding a central high-Z crystal scintillator. We can monitor individual Compton scatters that occur in the plastics and determine whether the photon is photo absorbed by the high-Z crystal or not. A Compton scattered photon that is immediately photo absorbed by the high-Z crystal constitutes a valid event. These valid events provide us with the interaction locations of each incident photon and ultimately produces a modulation pattern fo...

  6. High accuracy measurement of the $^{235}$U(n,f) reaction cross-section in the 10-30 keV neutron energy range

    The analysis of the neutron flux of n_TOF (in EAR1) revealed an anomaly in the 10-30 keV neutron energy range. While the flux extracted on the basis of the $^{6}$Li(n,t)$^{4}$He and $^{10}$B(n,$\\alpha$)$^{7}$Li reactions mostly agreed with each other and with the results of FLUKA simulations of the neutron beam, the one based on the $^{235}$U(n,f) reaction was found to be systematically lower, independently of the detection system used. A possible explanation is that the $^{235}$U(n,f) crosssection in that energy region, where in principle should be known with an uncertainty of 1%, may be systematically overestimated. Such a finding, which has a negligible influence on thermal reactors, would be important for future fast critical or subcritical reactors. Furthermore, its interest is more general, since the $^{235}$U(n,f) reaction is often used at that energy to determine the neutron flux, or as reference in measurements of fission cross section of other actinides. We propose to perform a high-accuracy, high-r...

  7. Time-resolved analysis of the X-ray emission of femtosecond-laser-produced plasmas in the 1.5-keV range

    Bastiani-Ceccotti, S.; Audebert, P.; Nagels-Silvert, V.; Geindre, J. P.; Gauthier, J. C.; Adam, J. C.; Héron, A.; Chenais-Popovics, C.

    Recent experimental results on ion beams produced in high-intensity laser-solid interactions indicate the presence of very intense electric fields in the target. This suggests the possibility of efficiently heating a solid material by means of the fast electrons created during the laser-solid interactions and trapped in the target, rather than by the laser photons themselves. We tested this mechanism by irradiating very small cubic aluminum targets with the LULI 100-TW, 300-fs laser at 1.06-μm wavelength. X-ray spectra were measured with an ultra-fast streak camera, coupled to a conical Bragg crystal, providing spectra in the 1.5-keV range with high temporal and spectral resolution. The results indicate the creation of a hot plasma, but a very low coupling between the rapid electrons and the solid. A tentative explanation, in agreement with other experimental results and with preliminary particle-in-cell (PIC) simulations, points out the fatal role of the laser prepulse.

  8. Measurement of U-235 absolute alpha value in the neutron energy range from 0.1 to 30 keV

    In order to measure the neutron-physical constants with high accuracy and to investigate ways of formation and decay of excited nuclei a method has been developed at the I.V. Kurchatov AEI, based on the gamma-quanta and neutrons multiplicity spectrometry. During 1974-1978 there have been constructed a number of multisectional 4π-detectors which have demonstrated great possibilities for this method. A detector permitting the required accuracy of measurements of neutron cross sections and their ratios has been chosen and designed on the basis of these works. The detector with 4π-geometry has 46 sections and was based on naI(Tl) crystals with the total volume of the scintillator of approx. 100 1. The detector was used at the 26-m station. The results of U-235 absolute alpha value measurements are presented. The measurements are carried out over the energy range from 0.1 to 30 keV with the high accuracy - better than 5%. The equipment parameters and measurement conditions are listed

  9. Developing a Compton polarimeter to measure polarization of hard x-rays in the 50-300 keV energy range

    Legere, Jason; Bloser, Peter L.; Macri, John R.; McConnell, Mark L.; Narita, Tomohiko; Ryan, James M.

    2005-08-01

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

  10. Determination of the effective atomic numbers and electron densities for YBaCuO superconductor in the range 59.5-136 keV

    The effective atomic numbers and electron densities of YBa2Cu3O7-δ superconductor at 59.5, 65.2, 77.1, 94.6, 122 and 136 keV were calculated by using the measured mass attenuation coefficients. Measurements were made by performing transmission experiments in a well-collimated narrow beam geometry set-up by employing Si(Li) detector with a resolution of 0.16 keV at 5.9 keV. These values are found to be in good agreement with theoretical values calculated based on XCOM data. The observed crystal structure of YBa2Cu3O7-δ superconductor is close to the theoretical structure. Zeff and Nel experimental values showed good agreement with the theoretical values for calcined and sintered YBa2Cu3O7-δ

  11. Determination of the effective atomic numbers and electron densities for YBaCuO superconductor in the range 59.5 136 keV

    Baltaş, H.; Çevik, U.

    2008-04-01

    The effective atomic numbers and electron densities of YBa 2Cu 3O 7-δ superconductor at 59.5, 65.2, 77.1, 94.6, 122 and 136 keV were calculated by using the measured mass attenuation coefficients. Measurements were made by performing transmission experiments in a well-collimated narrow beam geometry set-up by employing Si(Li) detector with a resolution of 0.16 keV at 5.9 keV. These values are found to be in good agreement with theoretical values calculated based on XCOM data. The observed crystal structure of YBa 2Cu 3O 7-δ superconductor is close to the theoretical structure. Zeff and Nel experimental values showed good agreement with the theoretical values for calcined and sintered YBa 2Cu 3O 7-δ.

  12. Spectroscopic monitoring of gamma-rays of Earth and space origin in the 150-6400 KeV range at Moussala BEO

    A gamma-spectrometer with a NaI detector and a suitable lead collimator directed to the sky was put in operation at Moussala BEO at an altitude of 2925 m above sea level. The gamma-rays spectrum in the 150–6500 keV energy interval was measured at two-hour intervals. In many cases, significant fluctuations were observed in the 222Rn lines intensity. Fluctuations of the gamma-rays intensity in the 2800–6400 keV energy interval were also observed. These gamma-rays originate from the interaction of various cosmic rays with Earth’s atmosphere. The device’s stability was controlled through the intensity of the 1460 keV gamma-line of the 40K background. Key words: Moussala, gamma-rays, NaI, detector, fluctuations, atmosphere

  13. First INTEGRAL observations of V404 Cygni during the 2015 outburst : spectral behavior in the 20 - 650 keV energy range

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

    2015-01-01

    In June 2015, 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 ($kT_0$ ~ 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 co...

  14. Bolometer characterisation with a specially developed cryogenic source having more than five peaks in the 1-6 keV range

    A very low temperature (10-50 mK), and at relatively low energy (typically 100 eV-10 keV), the linearity and resolution of bolometers need to be carefully tested. Commercially available sources below 6 keV are rate and difficult to cool down. We have developed a specially designed compact X-ray source where 55Fe is combined with an ion-exchange membrane containing more than three fluorescent elements. More than five peaks can be identified form 1 keV to 6.5 keV. A spectrum obtained with a 0.5 mg composite diamond bolometer, allowing a good measurement of linearity and resolution as a function of energy is presented. It is compared with a spectrum of the same source measured with a classical germanium detector. Since bolometer detectors have neither window, nor dead layer effects. Bolometer spectra obtained with these sources could be used to directly calibrate the efficiency response of classical detectors at very low energy. (orig.)

  15. Study of Radiation Shielding Properties of selected Tropical Wood Species for X-rays in the 50-150 keV Range

    S. Aggrey-Smith; K. Preko; F. W. Owusu; J.K. Amoako

    2016-01-01

    This paper compares the attenuation coefficients of 20 tropical hard wood species based on their linear and mass attenuation and half value layer (HVL) properties for X-rays of energy 50–150 keV using a narrow collimated beam from a Cs-137 source. The narrow collimated beam method made corrections from multiple and small-angle scatterings of photons unnecessary. The attenuation depended on the chemical composition and densities of the wood species. The linear attenuation coefficients of wood ...

  16. Efficiency calibration for HPGe detector using different sample densities and different volumes in the energy range 63.3 and 2614.7 keV

    Different density samples were chosen to find the relation between the sample density and the detector efficiency. All samples selected were mixed with a known weight of monazite material which contains known concentrations of 238U and 232Th. These samples are bran, water, soil and sand which have densities of 0.4513, 1.0, 1.322 and 1.869 g/cm3 respectively. Five gamma ray energie lines were selected for this study these are 92.6 keV of 234Th (U-series), 129.1 and 911.1 keV of 228Ac and 583.1 and 2614.7 keV of 208 Tl (Th-series). The obtained results showed that there are exponential decay relations between sample densities and the detector efficiency at all gamma ray energie lines selected. Also the relation between sample densities and the absolute efficiency of the detector used was studied at the same gamma-ray energy lines and the same results were obtained. The variation of absolute efficiency of the detector according to the densities was attributed mainly to the effect of the mass absorption coefficient of the different materials

  17. Study of Radiation Shielding Properties of selected Tropical Wood Species for X-rays in the 50-150 keV Range

    S. Aggrey-Smith

    2016-03-01

    Full Text Available This paper compares the attenuation coefficients of 20 tropical hard wood species based on their linear and mass attenuation and half value layer (HVL properties for X-rays of energy 50–150 keV using a narrow collimated beam from a Cs-137 source. The narrow collimated beam method made corrections from multiple and small-angle scatterings of photons unnecessary. The attenuation depended on the chemical composition and densities of the wood species. The linear attenuation coefficients of wood species at 50–150 keV were highest for Pterygota macrocarpa (4.53 m−1 and lowest for Antiaris africana (1.24 m−1; the mass attenuation coefficient was highest for Triplochiton scleroxylon (17.62 m2/kg and lowest for Nesogordonia papaverifera (2.27 m2/kg.The HVL was highest for Antiaris africana (0.27 m and lowest for Pterygota macrocarpa (0.149 m. Pterygota macrocarpa of about 0.36 m thickness could serve as a more affordable radiation shielding material against secondary scatter and leakage radiations in place of lead, copper or concrete for low X-ray radiations up to 150 keV.

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

    Antier, S; Ferrando, P

    2015-01-01

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

  19. Linear and mass attenuation coefficient for CdTe compound of X-rays from 10 to 100 keV energy range in different phases

    The Full Potential Linear Muffin Tin Orbitals method within the density functional theory has been utilized to calculate structural and electronic properties of the CdTe compound. We have checked that the CdTe has two phase-transitions from zinc-blend to cinnabar and from cinnabar to rocksalt. We have found that the rigidity, the energy and the nature of the gap change according to the phase change, so we can predict that a CdTe detector may have different behaviors in different phase conditions. In order to investigate this behavior change, the linear and the mass attenuation coefficients of X-ray in rocksalt, zinc-blend and cinnabar structures are calculated from 10 keV to100 keV, using the XCOM data. We have found that when CdTe undergoes a phase transition from zinc-blend to cinnabar, its linear attenuation coefficient decreases down to a value of about 100 times smaller than its initial one, and when it undergoes a transition from cinnabar to rocksalt it increases up to a value about 90 times larger than its initial one

  20. Plasma X-ray emission in the 20-500 keV range during lower hybrid current drive on Alcator

    An array of eight 1'' x 3'' NaI scintillators has been used to collect plasma hard x-ray spectra (E/sub γ/>20 keV) emitted perpendicular to the magnetic axis during lower hybrid current drive on Alcator. The spectra exhibit a tail extending out to at least 300 keV and the profiles are generally peaked. These results show that the slope of the x-ray spectra increases with increasing plasma radius. Equivalently, the emission profiles tend to broaden with increasing photon energy. Also, the x-ray spectra slope increases at each radial location as the relative phasing of adjacent waveguides in the grill antenna is decreased. Preliminary results also suggest that the x-ray spectra tend to flatten and that the emission profiles tend to peak up with decreasing plasma density or increasing magnetic field. In addition, the initial results of an array for measuring the high energy x-ray emission from Alcator as a function of the emission angle relative to the magnetic axis are presented

  1. Linear and mass attenuation coefficient for CdTe compound of X-rays from 10 to 100 keV energy range in different phases

    Saim, A., E-mail: saim1989asma@gmail.com; Tebboune, A.; Berkok, H.; Belameiri, N.; Belbachir, A.H.

    2014-07-25

    The Full Potential Linear Muffin Tin Orbitals method within the density functional theory has been utilized to calculate structural and electronic properties of the CdTe compound. We have checked that the CdTe has two phase-transitions from zinc-blend to cinnabar and from cinnabar to rocksalt. We have found that the rigidity, the energy and the nature of the gap change according to the phase change, so we can predict that a CdTe detector may have different behaviors in different phase conditions. In order to investigate this behavior change, the linear and the mass attenuation coefficients of X-ray in rocksalt, zinc-blend and cinnabar structures are calculated from 10 keV to100 keV, using the XCOM data. We have found that when CdTe undergoes a phase transition from zinc-blend to cinnabar, its linear attenuation coefficient decreases down to a value of about 100 times smaller than its initial one, and when it undergoes a transition from cinnabar to rocksalt it increases up to a value about 90 times larger than its initial one.

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

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

  3. Charge-transfer cross sections of ground state He+ ions in collisions with He atoms and simple molecules in the energy range below 4.0 keV

    Charge-transfer cross sections of the ground state He+ ions in collisions with He atoms and simple molecules (H2, D2, N2, CO and CO2) have been measured in the energy range of 0.20 to 4.0 keV with the initial growth rate method. Since previously published experimental data are scattered in the low energy region, the present observations would provide reasonably reliable cross section data below 4 keV. The charge transfer accompanied by dissociation of product molecular ion can be dominant at low energies for molecular targets. In He+ + D2 collisions, any isotope effect was not observed over the present energy range, compared to H2 molecule. (author)

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

    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).

  5. Calculations of electron stopping powers for 41 elemental solids over the 50 eV to 30 keV range with the full Penn algorithm

    We present mass collision electron stopping powers (SPs) for 41 elemental solids (Li, Be, graphite, diamond, glassy C, Na, Mg, Al, Si, K, Sc, Ti, V, Cr, Fe, Co, Ni, Cu, Ge, Y, Nb, Mo, Ru, Rh, Pd, Ag, In, Sn, Cs, Gd, Tb, Dy, Hf, Ta, W, Re, Os, Ir, Pt, Au, and Bi) that were calculated from experimental energy-loss-function data with the full Penn algorithm for electron energies between 50 eV and 30 keV. Improved sets of energy-loss functions were used for 19 solids. Comparisons were made of these SPs with SPs calculated with the single-pole approximation, previous SP calculations, and experimental SPs. Generally satisfactory agreement was found with SPs from the single-pole approximation for energies above 100 eV, with other calculated SPs, and with measured SPs.

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

    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 7–12 keV 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. - Highlights: • The X-ray attenuation coefficients were measured in biological and geological samples. • The difference between the attenuation coefficients in biological samples reached 47%. • The liver sample had the smallest attenuation coefficients. • The theoretical values for liver sample differ from the experimental ones by 2%

  7. Electron transport simulation in the range 1 keV-4 MeV for the purpose of high-resolution dosimetric application

    Cobut, V. [Univ. de Cergy-Pontoise, Neuville/Oise (France). Lab. Pharmacophores Redox, Phytochimie et Radiobiologie; Cirioni, L.; Patau, J.P. [Univ. Paul Sabatier, Toulouse (France). Faculte de Pharmacie

    2001-07-01

    Experimental spectrometry and dosimetry can offer some reliable answers. However, they are not easy to implement in some specific situations. Furthermore, information on dose distributions cannot always be obtained with the desirable geometrical resolution. A way to get rid of these disadvantages consist in simulating every successive individual interactions suffered by electrons and photons along their path. We applied this principle to simulate the response of a detector placed in the field of beta-gamma sources, which maximum energy does not exceed 4 MeV. A part of this work is presented here, which concerns Monte Carlo simulation of electron transport in materials encountered in experimental dosimetric devices. Electrons were followed down to a cutoff energy of 1 keV. (orig.)

  8. Study of natMg(d,d0) reaction at detector angles between 90° and 170°, for the energy range Ed,lab=1660–1990 keV

    In the present work, the study of the natMg(d,d0) is presented for the energy range Ed,lab = 1660–1990 keV (in steps of 5 keV), for detector angles between 90° and 170°. Elastic scattering data for two forward angles (55° and 70°) were also obtained. In order to validate the obtained experimental results a thick Mg sample with Au evaporated on top was fabricated and benchmarking measurements were performed at various deuteron beam energies. The results of the present work are complementary to the recently published 24Mg(d,p0,1,2) reaction cross section data, thus facilitating the simultaneous depth profiling study of magnesium by both the d-NRA and EBS techniques

  9. Dependence of spectral shape of bremsstrahlung spectra on atomic number of target materials in the photon energy range of 5-30 keV

    Dependence of spectral shape of total bremsstrahlung spectra i.e. the sum of ordinary bremsstrahlung (OB) and polarization bremsstrahlung (PB), on the atomic number (Z) of target materials (Al, Ti, Sn and Pb), produced by continuous beta particles of 90Sr and 204Tl, has been investigated in the photon energy region of 5-30 keV. It has been found that the spectral shape of total bremsstrahlung spectra, in terms of S (k, Z) i.e. the number of photons of energy k per moc2 per beta disintegration, is not linearly dependent on the atomic number (Z) of the target material and rather it is proportional to Zn. At lower photon energies, the index values ‘n’ of Z-dependence are much higher than unity, which is due to the larger contribution of PB into OB. The decrease in ‘n’ values with increase of photon energy is due to the decrease in contribution of PB into OB. It is clear that the index ‘n’ values obtained from the modified Elwert factor (relativistic) Bethe-Heitler theory, which include the contribution PB into OB, are in agreement with the experimentally measured results using X-PIPS Si(Li) detector. Hence the contribution of PB into the formation of a spectral shape of total bremsstrahlung spectra plays a vital role.

  10. Development of an X-ray imaging system within 10-30 keV spectral range based on organic or inorganic scintillator

    This thesis aims at developing an x-ray imaging system intended for the Laser Mega Joule, within the framework of Inertial Confinement Fusion (ICF) experiments. ICF aims at yielding thermonuclear energy through laser-driven fusion of a deuterium-tritium mix. The operational function of our system is to acquire an image of the 10-30 keV x-rays emitted by the maximally compressed micro-balloon, with spatial resolution better than 10 μm. The presented system is only a part of a complete diagnostic system, which normally includes an x-ray optical subsystem. Our system conception largely takes vulnerability into account. The ignition phase of ICF yields 1016 neutrons, with energies scaling up to 14 MeV. The neutrons generate such a hard surrounding with effects scaling down from image degradation up to instrumentation destruction. The presented system consists in a scintillator which is focused on a CCD camera through a catadioptric image transport system. An innovation work has been lead on scintillators to provide an answer to specifications greatly influenced by vulnerability. Those thesis works lead to an imaging system allowing to deport the CCD camera by 4 meters from the scintillator, with 100 μm spatial resolution in the scintillator plane. Those works have paved the way to outlooks such as enhancement of organic loaded scintillators compositions and improvement of optical relay system. (author)

  11. Simple parametrization of photon mass energy absorption coefficients of H-, C-, N- and O-based samples of biological interest in the energy range 200–1500 keV

    V Manjunathaguru; T K Umesh

    2009-02-01

    In this paper, we provide polynomial coefficients and a semi-empirical relation using which one can derive photon mass energy absorption coefficient of any H-, C-, N-, O-based sample of biological interest containing any other elements in the atomic number range 2–40 and energy range 200–1500 keV. More interestingly, it has been observed in the present work that in this energy range, both the mass attenuation coefficients and the mass energy absorption coefficients for such samples vary only with respect to energy. Hence it was possible to represent the photon interaction properties of such samples by a mean value of these coefficients. By an independent study of the variation of the mean mass attenuation coefficient as well as mass energy absorption coefficient with energy, two simple semi-empirical relations for the photon mass energy absorption coefficients and one relation for the mass attenuation coefficient have been obtained in the energy range 200–1500 keV. It is felt that these semi-empirical relations can be very handy and convenient in biomedical and other applications. One possible significant conclusion based on the results of the present work is that in the energy region 200–1500 keV, the photon interaction characteristics of any H-, C-, N-, O-based sample of biological interest which may or may not contain any other elements in the atomic number range 2–40 can be represented by a sample-independent (single) but energy-dependent mass attenuation coefficient and mass energy absorption coefficient.

  12. Neutron cross section evaluations of europium isotopes in 1 keV - 30 MeV energy range. Format - validation - comparison; Evaluation de sections efficaces pour des neutrons incidents sur des isotopes d'europium aux energies 1 keV - 30 MeV. Format - validation - comparaison

    Dossantos-Uzarralde, P.; Le Luel, C.; Bauge, E. [CEA Bruyeres le Chatel, 91 (France). Dept. de Physique Theorique et Appliquee

    2004-07-01

    This paper presents neutron cross section evaluations of Europium isotopes. The cross sections are evaluated in 1 keV - 30 MeV energy range for the isotopes {sup 146}Eu, {sup 147}Eu, {sup 148}Eu, {sup 149}Eu, {sup 150}Eu, {sup 151}Eu, {sup 152}Eu, {sup 153}Eu, {sup 154}Eu in their ground state. This evaluation includes cross section productions of the long life isomeric states. Special attention is put on the options used for the description of the files written in ENDF-6 format. The final issue is a proposal of a new breed of ENDF-6 formatted neutron activation file. (authors)

  13. Measurement of mass attenuation coefficients of Eremurus–Rhizophora spp. particleboards for X-ray in the 16.63–25.30 keV energy range

    The roots of Eremurus spp. were used as a bio-adhesive in the fabrication of Rhizophora spp. particleboards. The mass attenuation coefficients of Eremurus–Rhizophora spp. particleboard of six samples with two different weight percentages of the Eremurus spp. root (6% and 12%) and three various Rhizophora spp. particle sizes (≤149 µm, 149–500 µm and 500–1000 µm) were determined by using X-ray fluorescence (XRF) photons in 16.63 keV and 25.30 keV of the photon energy range. The results were compared with theoretically calculated mass attenuations using the XCOM computer program for younger-age (breast 1: 75% muscle+25% fat), middle-age (breast 2: 50% muscle+50% fat), and old-age (breast 3: 25% muscle+75% fat) breasts. The results indicated that Eremurus–Rhizophora spp. particleboard is the appropriate suitable phantom in the diagnostic energy region. The mass attenuation coefficient in the low weight percentage of the bio-adhesive and the large Rhizophora spp. particle size were found very close to breast 1. Moreover the mass attenuation coefficient of the sample with high weight percentage of the bio-adhesive and small Rhizophora spp. particle size was found very close to water as a standard material phantom. In addition, the viscosity of dissolved Eremurus spp. root in water could be considerably higher than that of formaldehyde-based adhesives, which affects on some properties such as high strength and high binding. - Highlights: • Rhizophora spp. particleboard bonded with Eremurus spp. root as a new phantom. • Mass attenuation coefficient of particleboard was measured in 16.63–25.30 keV range. • Mass attenuation coefficient particleboard was affected by particle size and %glue. • Mass attenuation coefficient of particleboard was close to water and young breast. • Viscosity of Eremurus was significantly higher than those of synthetic adhesives

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

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

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

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

    1997-11-01

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

  16. An experimental study of charge exchange process in the energy range 1-30 keV during the passage of alkali metal ions and atoms through cesium and potassium vapour

    An experimental study is presented of the charge exchange processes in the energy range of about 1-30 keV during the passage of positive alkali ions and alkali atoms through potassium and cesium vapour. The experimental set-up designed for this experiment includes a thermionic source for positive alkali ions with an acceleration stage, a first charge exchange cell to produce fast alkali atoms, a second charge exchange cell with a surface ionisation detector to determine the alkali metal vapor target thickness and a detection system with electrostatic bending of the charged secondary species. The maximum negative ion yield has been determined for the collision systems Li+ + K, Na+ + K, K+ + K, and Rb+ + K, and for another eleven systems the charge transfer cross-sections have been measured too. (orig./GG)

  17. High resolution measurement of the 234U(n,f) cross section in the neutron energy range from 0.5 eV to 100 keV

    The 234U(n,f) cross section has been measured in the energy range from 0.5 eV to 100 keV at the GELINA neutron time-of flight facility of the Institute for Reference Materials and Measurements in Geel using highly enriched 234U samples. Two independent measurements were performed: one in a low detection geometry (15% of 2 π) and another in a 2 π detection geometry. A235U(n,f) cross-section measurement was performed under the same experimental conditions, allowing a reliable correction for the 235U(n,f) contribution to the yield. Special attention has been given to the strongest resonance at 5.16 eV and to the fission resonance integral If for which large discrepancies are reported in the literature. (authors)

  18. 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

    We use the x-ray extended-range technique (XERT) [Chantler et al., Phys. Rev. A 64, 062506 (2001)] to measure the mass attenuation coefficients of molybdenum in the x-ray energy range of 13.5-41.5 keV 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

  19. The x-ray calibration facility of the laser integration line in the 0.9-10 keV range: The high energy x-ray source and some applications

    The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented.

  20. Theoretical Study of Secondary Electron Yield in Energy Range of 10 ~ 30 keV%10~30 keV二次电子发射系数的表达式

    谢爱根; 王祖松; 刘战辉; 詹煜; 吴红艳

    2013-01-01

    Here we addressed the theoretical subject of the secondary electron emission,in the energy range of 10 ~30keY.First,the formulae of the maximum second electron yield (δm),and the average number of secondary electrons released per primary electron with fairly high incident energy (δPE) were derived,respectively.Next,a general expression of δ in terms of the variables,including δm,atomic number,atomic weight,material density,back-scattering coefficient (γ),back-scattering coefficient at high energy (η),parameter A,energy exponent (n),and the incident energy of primary electron,was obtained,on the basis of the influence of δm and δPE on the secondary electron yield at high energy (δ).The parameter A and energy exponent n,in the energy range of 10 ~ 30 keV for some emitters of interest,were modeled and calculated with the software package ESTAR.The experimentally measured and calculated results of δ with the general formula were compared.The comparison result shows that when it comes to the secondary electron emission in the energy range of 10~ 30 keV,the newly-developed general formula of δ works fairly well for metals,semi-metals and element semiconductors.%根据二次电子发射的主要物理过程和特性,推导出最大二次电子发射系数(δm)的表达式.还推导出平均每个高能原电子发射的二次电子数(δPE)的表达式.根据δPE、δm和高能二次电子发射系数(δ)之间的关系,推导出以δm、原子序数、原子质量数、物质密度、背散射系数、高能背散射系数、参数A、能量幂次(n)和原电子入射能量为变量δ的通式.用ESTR程序计算出一些材料的10~ 30 keV能量范围内的参数A和n.用该通式计算出δ并与相应的实验值进行了比较,结果表明,成功地推导出金属、半金属和元素半导体10~ 30 keV的δ通式.

  1. kev neutron capture in zirconium-91

    The neutron capture cross section of 91Zr has been measured with high resolution (ΔE/E approximately 0.2 per cent) between 3 and 30 keV. Values of the gGAMMAsub(n)GAMMAsub(γ) for 119 resonances in this energy range have been obtained. The average capture cross section is consistent with values of = = 200. (author)

  2. Study of the collisional destruction of neutral hydrogen atoms in the ground state H(12S) and in the metastable state H(22S) on different rare gas targets in the 0.5 to 3.0 keV level energy range

    The total destruction cross-sections of H(22S) on rare gases and hydrogen are studied in the energy range 50 to 3000 eV, and the electron loss and electron capture cross-sections from H(12S) and H(22S) in the energy range 0.5 to 3 keV. The de-excitation cross-sections are deduced

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

    Cavinato, C.C. [Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, 05508-000 Sao Paulo, SP (Brazil); Campos, L.L., E-mail: lcrodri@ipen.b [Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, 05508-000 Sao Paulo, SP (Brazil)

    2010-07-21

    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.

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

    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.

  5. Measurement of the 232Th capture cross section in the energy region 5 keV-150 keV

    both the so-called 'open beam' background and of the contribution due to scattered neutrons. The normalisation constant was determined from a resonance shape analysis of the well isolated and nearly saturated resonances at 21.8 eV and 23.5 eV, with a peak transmission of respectively 4.7% and 0.9%. To estimate the systematic uncertainty related to the normalisation procedure, the experimental data were fitted in different energy regions, using resonance parameters from several evaluation data file. The final normalisation and energy calibration will be obtained with resonance parameters resulting from recent transmission measurements. We used the SESH code6 to correct for self-shielding and multiple scattering effects was . The preliminary capture cross-section values are presented, together with the ENDF-B VI values and the experimental data obtained by Wisshak et al., Macklin et al. and Karamanis et al. Our data in the 5-100 keV region, agree within a 7 % systematic uncertainty with the data obtained by Macklin et al. We do not confirm the large discrepancies at lower neutron energies reported by Wisshak et al. Our data between 5-80 keV are systematically 10% higher compared to the evaluated data. In the 80-100 keV region the differences are much smaller. To confirm the present data an additional measurement campaign, including the measurement of the Au(n,γ) cross-section, was performed. The analysis of this data is in progress

  6. Pourbaix diagrams for the system copper-chlorine at 5-100 deg C

    Beverskog, B. [Studsvik Material AB, Nykoeping (Sweden); Puigdomenech, I. [Studsvik Eco and Safety AB, Nykoeping (Sweden)

    1998-04-01

    Pourbaix diagrams for the copper-chlorine system in the temperature interval 5-100 deg C have been revised. Predominance diagrams for dissolved copper containing species have also been calculated. Two different total concentrations of each dissolved element, 10{sup -4} and 10{sup -6} molal for copper and 0.2 and 1.5 molal for chlorine have been used in the calculations. Chloride is the predominating chlorine species in aqueous solutions. Presence of chloride increases the corrosion regions of copper at the expense of the immunity and passivity regions in the Pourbaix diagrams. CuCl{sub 2} {center_dot} 3Cu(OH){sub 2} is the only copper-chloride solid phase that forms at the concentrations of chlorine studied. However, its stability area decreases with increasing temperature. The ion CuCl{sub 2}{sup -} predominates at all temperatures at [Cl(aq)]{sub tot}=0.2 molal and this reduces the immunity and passivity areas. A corrosion region exists between the immunity and passivity regions at 100 deg C at [Cu(aq)]{sub tot}=10{sup -6} and [Cl(aq)]{sub tot}=0.2 molal. At the chlorine concentration of 1.5 molal the corrosion region exists in the whole temperature range investigated. The ion CuCl{sub 3}{sup 2-} predominates at 5-25 and 100 deg C, while CuCl{sub 2}{sup -} predominates at 50-80 deg C at [Cl(aq)]{sub tot=}1-5 molal. A copper concentration of 10{sup -4} molal reduces the corrosion areas due to expansion of the immunity and passivity areas. However, a corrosion region still exists between the immunity and passivity regions at all investigated temperatures at pH{sub {Tau}}<9.5 and 1.5 molal chloride concentration. According to our calculations the copper canisters in the deep nuclear waste repository should not corrode at the copper concentration of 10{sup -6} molal and the chloride concentration of 0.2 molal. However, at 80-100 deg C the equilibrium potentials postulated for the Swedish nuclear repository are dangerously close to a corrosion situation. According to

  7. Pourbaix diagrams for the system copper-chlorine at 5-100 deg C

    Pourbaix diagrams for the copper-chlorine system in the temperature interval 5-100 deg C have been revised. Predominance diagrams for dissolved copper containing species have also been calculated. Two different total concentrations of each dissolved element, 10-4 and 10-6 molal for copper and 0.2 and 1.5 molal for chlorine have been used in the calculations. Chloride is the predominating chlorine species in aqueous solutions. Presence of chloride increases the corrosion regions of copper at the expense of the immunity and passivity regions in the Pourbaix diagrams. CuCl2 · 3Cu(OH)2 is the only copper-chloride solid phase that forms at the concentrations of chlorine studied. However, its stability area decreases with increasing temperature. The ion CuCl2- predominates at all temperatures at [Cl(aq)]tot=0.2 molal and this reduces the immunity and passivity areas. A corrosion region exists between the immunity and passivity regions at 100 deg C at [Cu(aq)]tot=10-6 and [Cl(aq)]tot=0.2 molal. At the chlorine concentration of 1.5 molal the corrosion region exists in the whole temperature range investigated. The ion CuCl32- predominates at 5-25 and 100 deg C, while CuCl2- predominates at 50-80 deg C at [Cl(aq)]tot=1-5 molal. A copper concentration of 10-4 molal reduces the corrosion areas due to expansion of the immunity and passivity areas. However, a corrosion region still exists between the immunity and passivity regions at all investigated temperatures at pHΤ-6 molal and the chloride concentration of 0.2 molal. However, at 80-100 deg C the equilibrium potentials postulated for the Swedish nuclear repository are dangerously close to a corrosion situation. According to our calculations the copper canisters in the Swedish repository corrode at 80-100 deg C at the chloride concentration of 1.5 molal

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

    Mohd Yusof, Mohd Fahmi, E-mail: mfahmi@usm.my; Hamid, Puteri Nor Khatijah Abdul; Tajuddin, Abdul Aziz [School of Physics, Universiti Sains Malaysia, 11800 Penang (Malaysia); Bauk, Sabar [School of Distance Education, Universiti Sains Malaysia, 11800 Penang (Malaysia); Hashim, Rokiah [School of Industrial Technologies, Universiti Sains Malaysia, 11800 Penang (Malaysia)

    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)

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

    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. A measurement of the electron-hole pair creation energy and the Fano factor in silicon for 5.9 keV X-rays and their temperature dependence in the range 80-270 K

    A measurement of the energy ω to create an electron-hole pair and its temperature dependence between 80 and 270 K has been made using a small Si p-i-n diode and 5.9 keV X-rays. A value of 3.73±0.09 eV with a gradient of -0.0131±0.0004% K-1 was found. The photo-peak dispersion D was also measured and from the values between 110 K and 235 K, the product ωF was found to be 0.441±0.005 eV. This is consistent with a constant Fano factor F of 0.118±0.004

  11. Performance of TEPCs at low pressures: some attempts to improve their dose equivalent response to the neutron energy range from 10keV to 1 MeV

    A TEPC, from its operational principle, fulfils reasonably well the requirements of an area monitor with a dose equivalent response nearly independent of neutron energy to be used for radiation protection dosimetry at various work places. However, between neutron energies from 10 keV to 1 MeV, which are of relevance for environments with strongly moderated neutron fields, the response of TEPCs with thin walls is too low. Attempts to increase the response in this energy region by modifying gas pressure, gas composition and wall thickness show that significant improvement first requires operation of the TEPC at lower simulated diameters compared with the 2 μm diameter commonly used. Preliminary investigations to improve the operational properties of TEPCs at low pressures are presented. (author)

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

    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).

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

    Koutroumpa, D; Raymond, J C; Kharchenko, V

    2008-01-01

    We present calculations of the heliospheric SWCX emission spectra and their contributions in the ROSAT 1/4 keV band. We compare our results with the soft X-ray diffuse background (SXRB) emission detected in front of 378 identified shadowing regions during the ROSAT All-Sky Survey (Snowden et al. 2000). This foreground component is principally attributed to the hot gas of the so-called Local Bubble (LB), an irregularly shaped cavity of ~50-150 pc around the Sun, which is supposed to contain ~10^6 K plasma. Our results suggest that the SWCX emission from the heliosphere is bright enough to account for most of the foreground emission towards the majority of low galactic latitude directions, where the LB is the least extended. In a large part of directions with galactic latitude above 30deg the heliospheric SWCX intensity is significantly smaller than the measured one. However, the SWCX R2/R1 band ratio differs slightly from the data in the galactic center direction, and more significantly in the galactic anti-ce...

  14. A determination of the Fano factor for germanium at 77.4K from measurements of the energy resolution of a 113cm3 HPGe gamma-ray spectrometer taken over the energy range from 14 to 6129 keV

    The Fano factor for germanium cooled to 77.4 K has been determined from a semiempirical analysis of the measured energy resolution of a HPGe γ-ray spectrometer of active volume 113.2 cm3. Twenty nine γ-ray energies spanning the range from 14 to 6129 keV were used in this study. The dispersion due to incomplete charge collection was assessed experimentally by making measurements over a wide range of applied bias. Plots of the peak centroid shift and the peak width squared against the reciprocal of the voltage applied to the detector, were non-linear. Both exhibited plateaus for large applied voltages. Thus, by operating in the plateau region, the Fano factor could be extracted from the variation of the observed line width as a function of energy, while the detector was known to be functioning close to the position of perfect charge collection. The value of the Fano factor obtained in this work, averaged over the energy range 14-6129 keV, was 0.112 ± 0.001. It is recommended that more, high quality, measurements be made. (author)

  15. The atmospheric fate of 0.5-100 micron dust observed as radar micrometeors at Arecibo Observatory.

    Mathews, J. D.; Janches, D.; Meisel, D. D.; Zhou, Q.-H.

    Radar micrometeor observations at Arecibo Observatory yield instantaneous Doppler speed and deceleration measurements that, combined with appropriate model atmosphere results, yield the ballistic parameter for many events. Assuming 3 gm/cc mass density and spherical particles, the ballistic parameter is converted to particle mass and size range. The observed size range is 0.5-100 micron radius. These measurements additionally provide daily and seasonal event rates and allow whole-earth mass flux estimates over the observable particle size distribution (Mathews et al., The micrometeor mass flux into the upper atmosphere: Arecibo results and a comparison with prior estimates, Geophysical Research Letters 28, 1929-1932, 2001). Updated mass fluxes will be presented. Further, we present information about the processes whereby the dust particles slow and disperse into the upper atmosphere. We find no evidence of simple ablation over the altitude range that these particles are observed as radar meteors. We do however find that a significant fraction of these particles catastrophically disintegrate and are likely not deposited in atomic form but rather into nanometer-sized smoke particles.

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

    Beckmann, Volker; Tueller, Jack

    2007-01-01

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

  17. Linear attenuation coefficients of tissues from 1 keV to 150 keV

    Böke, Aysun

    2014-09-01

    The linear attenuation coefficients and three interaction processes have been computed for liver, kidney, muscle, fat and for a range of x-ray energies from 1 keV to 150 keV. Molecular photoelectric absorption cross sections were calculated from atomic cross section data. Total coherent (Rayleigh) and incoherent (Compton) scattering cross sections were obtained by numerical integration over combinations of F2m(x) with the Thomson formula and Sm(x) with the Klein-Nishina formula, respectively. For the coherent (Rayleigh) scattering cross section calculations, molecular form factors were obtained from recent experimental data in the literature for values of xlinear attenuation coefficients. In general, good agreement is obtained. The molecular form factors and scattering functions and cross sections are incorporated into a Monte Carlo program. The energy distributions of x-ray photons scattered from tissues have been simulated and the results are presented.

  18. Sputtering of solid neon by keV hydrogen ions

    Ellegaard, Ole; Schou, Jørgen; Sørensen, H.

    Sputtering of solid Ne with the hydrogen ions H+1, H+2 and H+3 in the energy range 1–10 keV/atom has been studied by means of a quartz microbalance technique. No enhancement in the yield per atom for molecular ions was found. The results for hydrogen ions are compared with data for keV electrons...

  19. W/SiC X-ray multilayers optimized for use above 100 keV

    Windt, D.L.; Dongey, S.; Hailey, C.J.;

    2002-01-01

    We have developed a new depth-graded multilayer system comprising W and SiC layers, suitable for use as hard X-ray reflective coatings operating in the energy range 100 - 200 keV. Grazing incidence X-ray reflectance at E=8 keV was used to characterize the interface widths, as well as the temporal...

  20. High-resolution detection of 100 keV electrons using avalanche photodiodes

    Ogasawara, K.; Hirahara, M.; Miyake, W.; Kasahara, S.; Takashima, T.; Asamura, K.; Saito, Y.; Mukai, T.

    2008-08-01

    With two electron beam sources, we have tested two new Hamamatsu [Hamamatsu Photonics K.K., Shizuoka, Japan ] avalanche photodiodes (APDs) of spl 3988 and spl 6098 to detect electron beams up to 100 keV. Though our previous results showed the effectiveness and the advantage of an APD to measure 2-40 keV electrons, its upper limit was not high enough to detect so-called medium-energy electrons. In addition to the limitation of its detectable range, the response at different energies was also not linear. These newly developed APDs, which have thicker depletion-layers, provide full coverage of this missing range along with a good linearity. The depletion-layer thickness was increased to 140 μm for both APDs, the dead-layer of spl 3988 became 10 times thicker than that of spl 6098. The thin-surface dead-layer and thick depletion-layer of spl 6098 allows the detection of electrons from 3 keV up to 100 keV with a good linearity and with an excellent energy resolution of 4 keV at 100-keV electrons. The wide dynamic range from 3 keV to 100 keV of those APDs will increase their appeal in detecting electrons for space plasma research.

  1. Linear attenuation coefficients of tissues from 1 keV to 150 keV

    The linear attenuation coefficients and three interaction processes have been computed for liver, kidney, muscle, fat and for a range of x-ray energies from 1 keV to 150 keV. Molecular photoelectric absorption cross sections were calculated from atomic cross section data. Total coherent (Rayleigh) and incoherent (Compton) scattering cross sections were obtained by numerical integration over combinations of F2m(x) with the Thomson formula and Sm(x) with the Klein–Nishina formula, respectively. For the coherent (Rayleigh) scattering cross section calculations, molecular form factors were obtained from recent experimental data in the literature for values of x<1 Å−1 and from the relativistic modified atomic form factors for values of x≥1 Å−1. With the inclusion of molecular interference effects in the coherent (Rayleigh) scattering, more accurate knowledge of the scatter from these tissues will be provided. The number of elements involved in tissue composition is 5 for liver, 47 for kidney, 44 for muscle and 3 for fat. The results are compared with previously published experimental and theoretical linear attenuation coefficients. In general, good agreement is obtained. The molecular form factors and scattering functions and cross sections are incorporated into a Monte Carlo program. The energy distributions of x-ray photons scattered from tissues have been simulated and the results are presented. - Highlights: • The inclusion of molecular interference effects will provide new information. • Results are compared with previously reported experimental and theoretical values. • Calculation is achieved in the presence of small concentrations of different atoms

  2. Nucleosynthesis confronts an unstable inert 17 keV state

    We study the cosmological consequences of an inert 17 keV state mixing with the electron neutrino. We find that the nucleosynthesis upper bound on the primordial helium abundance prohibits the existence of such a state, unless its lifetime falls into the range 6x10-4svac-2s. In this range the decay occurs after the chemical decoupling of the electron neutrinos and before the beginning of the nucleosynthesis, with the result that the predicted helium abundance can be lower than what it would be in the standard scenario. (orig.)

  3. Characteristics of > 290 keV magnetosheath ions

    A. Rigas

    Full Text Available We performed a statistical analysis of 290-500 keV ion data obtained by IMP-8 during the years 1982-1988 within the earth's magnetosheath and analysed in detail some time periods withdistinct ion bursts. These studies reveal the following characteristics for magnetosheath 290-500 keV energetic ions: (a the occurrence frequency and the flux of ions increase with increasing geomagnetic activity as indicated by the Kp index; the occurrence frequency was found to be as high as P > 42% for Kp > 2, (b the occurrence frequency in the dusk magnetosheath was found to be slightly dependent on the local time and ranged between ~30% and ~46% for all Kp values; the highest occurrence frequency was detected near the dusk magnetopause (21 LT, (c the high energy ion bursts display a dawn-dusk asymmetry in their maximum fluxes, with higher fluxes appearing in the dusk magnetosheath, and (d the observations in the dusk magnetosheath suggest that there exist intensity gradients of energetic ions from the bow shock toward the magnetopause. The statistical results are consistent with the concept that leakage of magnetospheric ions from the dusk magnetopause is a semi-permanent physical process often providing the magnetosheath with high energy (290-500 keV ions.Key words. Magnetospheric physics (magnetosheath; planetary magnetospheres. Space plasma physics (shock waves.

  4. Use of proportional counter in X-Ray spectrometry between 5 and 100 keV. Application to the detection of fission products and to the determination of absolute X-Ray disintegration rates

    The measurement of electromagnetic radiations is difficult in the energy range 20-100 keV. We made suitable for this purpose a regular proportional counter, modifying both the nature and pressure of the gaseous mixture filling the detector volume. We selected the CPEN-SAIP counter, which is able to withstand such modifications. In the energy range considered, the counter is to be standardized with radioactive sources. Such standards were selected according to their disintegration schemes. We thus defined the conditions of use (resolution, yield) of the CPN counter, filled with an argon-methane mixture under a pressure of about 3 bars, in the energy range 5-100 keV. With such an equipment, we were able to measure the absolute disintegration rate for the X-rays of 133 Ba and 75 Se, then to perform the study of a mixed fission products sample. In the same way, we used xenon-based gaseous mixtures, in order to improve the detector yield; in the later case, we carefully examined the limitations introduced by the presence of many parasite rays emitted by the gas. We thus displayed in addition to the leakage peak, the fluorescence ray of the gas, whose origin is difficult to explain. (author)

  5. Interaction between solid nitrogen and 1--3-keV electrons

    Experimental studies were made of the interaction between solid nitrogen and beams of 1--3-keV electrons. The projected range for the electrons was measured by means of the mirror-substrate method (gold substrate), giving the result 9.02 x 1016 E/sup 1.75/ molecules/cm2 with the energy given in keV. The escape depth for secondary electrons was studied by means of the equivalent-substrate method (carbon substrate). The results varied from 280 A at 1 keV to 400 A at 3 keV. Measurements were also made of the secondary-electron-emission coefficient, which varied from 2.3 el/el at 1 keV to 1.2 el/el at 3 keV. At 3 keV, the SEE coefficient is 12 times that for solid deuterium. This is attributed partly to the larger production rate for low-energy electrons in nitrogen and partly to the larger escape probability for these electrons. Moreover, measurements were made of the electron-reflection coefficient, both for solid nitrogen and for the carbon substrate. For nitrogen, it varied from 0.17 el/el at 1 keV to 0.13 el/el at 3 keV, and for carbon it varied from 0.13 to 0.12. The observations are discussed and comparisons made with other theoretical and experimental results. The agreement ranges from good to fair

  6. Interaction between Solid Nitrogen and 1-3-keV Electrons

    Schou, Jørgen; Sørensen, H.

    1978-01-01

    Experimental studies were made of the interaction between solid nitrogen and beams of 1-2-keV electrons. The projected range for the electrons was measured by means of the mirror-substrate method (gold substrate), giving the result 9.02×1016 E1.75 molecules/cm2 with the energy given in keV. The...... to fair...

  7. A radio frequency helical deflector for keV electrons

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

  8. A radio frequency helical deflector for keV electrons

    Gevorgian, L.; Ajvazyan, R.; Kakoyan, V. [A.I. Alikhanyan National Science Laboratory, Yerevan (Armenia); Margaryan, A., E-mail: mat@mail.yerphi.am [A.I. Alikhanyan National Science Laboratory, Yerevan (Armenia); Annand, J.R.M. [Department of Physics & Astronomy, University of Glasgow, G12 8QQ Scotland (United Kingdom)

    2015-06-11

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

  9. RHESSI Observations of the Solar Flare Iron-line Feature at 6.7 keV

    Phillips, K. J. H.; Chifor, C.; Dennis, B. R.

    2006-01-01

    Analysis of RHESSI 3--10 keV spectra for 27 solar flares is reported. This energy range includes thermal free--free and free--bound continuum and two line features, at 6.7keV and 8keV, principally due to highly ionized iron (Fe). We used the continuum and the flux in the so-called Fe-line feature at 6.7keV to derive the electron temperature T_e, the emission measure, and the Fe-line equivalent width as functions of time in each flare. The Fe/H abundance ratio in each flare is derived from the...

  10. Investigation of multilayer X-ray optics for 6 keV to 20 keV energy range

    Oberta, Peter; Platonov, Y.; Flechsig, U.

    2012-01-01

    Roč. 19, č. 5 (2012), s. 675-681. ISSN 0909-0495 Institutional research plan: CEZ:AV0Z10100522 Keywords : X-ray optics * multilayer * energy resolution Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.186, year: 2012 http://journals.iucr.org/s/issues/2012/05/00/issconts.html

  11. Triton production cross section in interaction of keV deuterons with {sup 13}C nucleus

    AL-Ohali, M.A.; Naqvi, A.A.; Khiari, F.Z. [King Fahd University of Petroleum and Minerals, Center for Applied Physical Sciences, Dhahran (Saudi Arabia); Rehman, Khateeb-ur; Nagadi, M.M.; Kidwai, S. [King Fahd University of Petroleum and Minerals, Department of Physics, Dhahran (Saudi Arabia)

    2002-08-01

    Triton production cross section has been measured in interaction of 200-350 keV deuteron with {sup 13}C nuclei. In this study excitation functions of {sup 13}C(d, t){sup 12}C reaction have been measured at eight angles in 10 keV energy steps over 200-350 keV deuteron energy range while angular distributions of {sup 13}C(d, t){sup 12}C reaction were measured at 200, 250, 270, 290, 310, 330 and 350 keV deuteron energies. The angular distributions of {sup 13}C(d, t){sup 12}C reaction are forward-peaked and are in disagreement with shape of previously reported data of {sup 13}C(d, t){sup 12}C reaction at 410 keV deuteron energy. On the contrary the shape of angular distribution measured in this study has a better agreement with the shape of angular distribution of {sup 13}C(d, t){sup 12}C reaction at 410 keV deuteron calculated using zero-range Distorted Wave Born Approximation (DWBA) model. (author)

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

    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.

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

    The total absorption coefficients for some selected organic compounds relevant to health physics, Triaflol BN (C3H4O2)n, Triaflol TN (C12H18O7)n, Kapton (C44H20O10)n, and Melinex (C10H8N4O4)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. (author)

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

    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).

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

    Iakubovskyi, Dmytro

    2015-01-01

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

  16. Re-measurement of the neutron-induced gamma-ray production cross sections for iron in the energy range 850 keV less than or equal to E/sub n/ less than or equal to 20. 0 MeV. [Tables

    Chapman, G.T.; Morgan, G.L.; Perey, F.G.

    1976-07-01

    Values of the gamma-ray production cross sections for neutron interactions with iron as reported by previous investigators have differed by as much as a factor of 1.5 or more at neutron energies greater than about 5 MeV. Because of this discrepancy, the measurements were repeated at ORNL using the ORELA as a pulsed source of neutrons with energies between 850 keV and 20 MeV. The data were obtained using a NaI(Tl) gamma-ray spectrometer oriented at an angle of 125/sup 0/ to the incident neutron beam. The sample was positioned in the beam at a distance of 47.35 meters from the neutron source. The resulting data, presented as differential cross sections (d/sup 2/sigma/d..cap omega..dE) for gamma rays between 0.7 and 10.5 MeV, show good agreement with some previously published data, but are significantly different from previous ORNL measurements for neutron energies greater than 5 MeV.

  17. Testing keV sterile neutrino dark matter in future direct detection experiments

    In this work we analyse the possibility of measuring sterile neutrino dark matter in direct detection experiments, such as XENON100 and its future stages. In particular we focus on the keV range, studying the interaction of these particles with electrons in bound states.

  18. Testing keV sterile neutrino dark matter in future direct detection experiments

    Campos, Miguel D.; Rodejohann, Werner [Max-Planck-Institut fuer Kernphysik, Heidelberg (Germany)

    2015-07-01

    In this work we analyse the possibility of measuring sterile neutrino dark matter in direct detection experiments, such as XENON100 and its future stages. In particular we focus on the keV range, studying the interaction of these particles with electrons in bound states.

  19. Spatial distribution of upstream magnetospheric ≥50 keV ions

    G. Kaliabetsos

    Full Text Available 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 ~50 keV magnetospheric ions from the dusk magnetopause, (2 nearly scatter free motion of ~50 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 ~16%-~34% in the upstream region.Key words. Interplanetary physics (energetic particles; planetary bow shocks

  20. Evaluation of the 232Th neutron capture cross section above 3 keV

    This memo describes an evaluation of the 232Th neutron capture cross section in the neutron energy range from 3 keV to 20 MeV. Most existing differential measurements are reviewed, and some data are renormalized to current values of the standards. Several experimentally determined sets of average resonance parameters are also discussed. From 3 to 50 keV the evaluated cross section is described by a set of average statistical resonance parameters. Above 50 keV the evaluated capture cross section is a smooth curve which follows the trend of the most recent measurements. The evaluated capture cross section is compared with many measurements and uncertainty estimates are given

  1. The 65 keV resonance in the {sup 17}O(p,alpha){sup 14}N thermonuclear reaction

    Sergi, M.L. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Spitaleri, C. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Coc, A. [CSNSM, UMR 8609, CNRS/IN2P3and Universite Paris Sud 11, Batiment 104, 91405 Orsay Campus (France); Mukhamedzhanov, A. [Cyclotron Institute, Texas A and M University, College Station, TX 77843 (United States); Burjan, S.V. [Nuclear Physics Institute of ASCR Rez near Prague (Czech Republic); Gulino, M. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Hammache, F. [IPN, IN2P3-CNRS et Universite de Paris-Sud 11, 91406 Orsay Cedex (France); Hons, Z. [Nuclear Physics Institute of ASCR Rez near Prague (Czech Republic); Irgaziev, B. [GIK Institute of Engineering Sciences and Technology Topi District Swabi NWFP (Pakistan); Kiss, G.G. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Kroha, V. [Nuclear Physics Institute of ASCR Rez near Prague (Czech Republic); La Cognata, M. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Centro Siciliano di Fisica Nucleare e Struttura della Materia, Catania (Italy); Lamia, L.; Pizzone, R.G. [Laboratori Nazionali del Sud, Catania (Italy); Dipartimento di Metodologie Fisiche e Chimiche per l' Ingegneria, Universita di Catania, Catania (Italy); Sereville, N. de [IPN, IN2P3-CNRS et Universite de Paris-Sud 11, 91406 Orsay Cedex (France); Somorjai, E. [ATOMKI, Debrecen (Hungary)

    2010-03-01

    The indirect measurement of {sup 17}O(p,alpha){sup 14}N cross section was performed by means of the Trojan Horse Method. This approach allowed to investigate the ultra-low energy range (E{sub c.m.}=0-300 keV) relevant for several astrophysics environments, where two resonant levels of {sup 18}F at E{sub c.m.}{sup R}=65 keV and E{sub c.m.}{sup R}=183 keV play a significant role in the reaction rate determination.

  2. Parity of the band head at 3710 keV in 99Rh using clover detector as Compton polarimeter

    R Palit; H C Jain; P K Joshi; S Nagaraj; B V T Rao; S N Chintalapudi; S S Ghugre

    2000-03-01

    Clover detector has been used as a Compton polarimeter to measure the linear polarization of -rays produced in heavy ion fusion reaction. The polarization sensitivity of the clover detector has been measured over -ray energies ranging from 386 to 1368 keV. The E1 multipolarity of the 1117 keV transition in 99Rh has been established using this polarimeter. This has resulted in the assignment of negative parity to the band head at 3710 keV in 99Rh.

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

    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.

  4. Steady State Sputtering Yields and Surface Compositions of Depleted Uranium and Uranium Carbide bombarded by 30 keV Gallium or 16 keV Cesium Ions

    Depleted uranium that included carbide inclusions was sputtered with 30keV gallium ions or 16kev cesium ions to depths much greater than the ions’ range, i.e. using steady state sputtering. The recession of both the uranium’s and uranium carbide’s surfaces and the ion corresponding fluences were used to determine the steady state target sputtering yields of both uranium and uranium carbide, i.e. 6.3 atoms of uranium and 2.4 units of uranium carbide eroded per gallium ion, and 9.9 uranium atoms and 3.65 units of uranium carbide eroded by cesium ions. The steady state surface composition resulting from the simultaneous gallium or cesium implantation and sputter-erosion of uranium and uranium carbide were calculated to be U86Ga14, (UC)70Ga30 and U81Cs9, (UC)79Cs21, respectively.

  5. Steady State Sputtering Yields and Surface Compositions of Depleted Uranium and Uranium Carbide bombarded by 30 keV Gallium or 16 keV Cesium Ions.

    Siekhaus, W. J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Teslich, N. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Weber, P. K. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-10-23

    Depleted uranium that included carbide inclusions was sputtered with 30-keV gallium ions or 16-kev cesium ions to depths much greater than the ions’ range, i.e. using steady-state sputtering. The recession of both the uranium’s and uranium carbide’s surfaces and the ion corresponding fluences were used to determine the steady-state target sputtering yields of both uranium and uranium carbide, i.e. 6.3 atoms of uranium and 2.4 units of uranium carbide eroded per gallium ion, and 9.9 uranium atoms and 3.65 units of uranium carbide eroded by cesium ions. The steady state surface composition resulting from the simultaneous gallium or cesium implantation and sputter-erosion of uranium and uranium carbide were calculated to be U₈₆Ga₁₄, (UC)₇₀Ga₃₀ and U₈₁Cs₉, (UC)₇₉Cs₂₁, respectively.

  6. Measurement of total absorption coefficient for four mixtures using X-rays from 13 keV up to 50 keV

    Many theoretical treatments of X-ray dosimetry require an accurate knowledge of the probabilities of various interactions with matter. For this purpose the available data of mass attenuation coefficients are normally used. However new measurements of total absorption coefficients are welcomed in order to upgrade the theoretical versus experimental data comparison. In this work the results of the measurements of the mass attenuation coefficients for some mixtures often used in X-ray dosimetry are reported. The total absorption coefficient for for some selected organic compounds relevant to health physics (Triaflol BN, Triaflol TN, Kapton, Melinex) were measured in the X-ray energy range from 13 keV up to 50 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. (author)

  7. Dosimetry at a 400 keV accelerator

    Miller, A.

    1992-01-01

    Absolute calorimetric dosimetry and relative dose mapping methods are described for a 400 keV electron accelerator used for polymer curing and crosslinking experiments. These methods of dosimetry are also useful at accelerators used in gas cleaning processes.......Absolute calorimetric dosimetry and relative dose mapping methods are described for a 400 keV electron accelerator used for polymer curing and crosslinking experiments. These methods of dosimetry are also useful at accelerators used in gas cleaning processes....

  8. Search for admixture of heavy neutrinos with masses between 5 and 55 keV

    Markey, J.; Boehm, F.

    1985-01-01

    Using a magnetic spectrometer at a momentum resolution of 0.3%, we have studied the beta spectrum from 35S. We do not see evidence for the admixture of a heavy neutrino to the usual light (m~0) ν̃e accompanying beta decay, in the mass range between 5 and 50 keV, with a limit for the mixing strength of |U|2

  9. Compton polarimeter for 10–30 keV x rays

    Weber, S.; Beilmann, C.; Shah, C.; Tashenov, S. [Physics Institute, Heidelberg University, 69120 Heidelberg (Germany)

    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.

  10. Compton polarimeter for 10-30 keV x rays

    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.

  11. The double ionisation of hydrogen by 5-30 keV protons

    The energy and angular distribution of pairs of fragment protons produced in H+-H2 collisions has been investigated in the energy range 5-30 keV. It is shown that the energy distribution is a simple transformation of the ground-state wavefunction of H2 and an experimental determination of the ground-state probability density distribution is presented. Total and differential double ionisation cross sections are found to be in accord with earlier measurements. (author)

  12. The Dynamic Range of LZ

    Yin, Jun

    2015-01-01

    The electronics of the LZ experiment, the 7-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to permit studies of physics where the energies deposited range from 1 keV of nuclear-recoil energy up to 3,000 keV of electron-recoil energy. The system is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achieva...

  13. Decays D → Kev, D → K*ev, D → πev in QCD sum rules method

    The form factors of the semileptonic decays D → Kev, D → K*ev, D → πev are calculated by means of the QCD sum rules method for the three-point correlators. The decay widths are obtained. Our results agree with the experimental data within the theoretical and the experimental uncertainties involved. The restriction on the Kobayashi-Maskava matrix elements Vcs, Vcd are found. (author). 22 refs, 1 fig

  14. Multilayer supermirrors: broadband reflection coatings for the 15- to 100-keV range

    Joensen, K. D.; Gorenstein, P.; Christensen, Finn Erland;

    1994-01-01

    Supermirrors are multilayer structures where the thickness of the layers down through the structure changes so that wide-band reflection occurs. The principles were developed in the mid-70's and have been used extensively for neutron optics. Absorption in the upper layers limits the attainable...... characterized. The measured X-ray reflectivities are well accounted for by the standard dynamical theories of multilayer reflection. Hard X-ray applications that could benefit from X-ray supermirror coatings include focusing and imaging instrumentation for astrophysics, and collimating and focusing device for...

  15. The dynamic range of LZ

    Yin, J.

    2016-02-01

    The electronics of the LZ experiment, the 7-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to permit studies of physics where the energies deposited range from 1 keV of nuclear-recoil energy up to 3,000 keV of electron-recoil energy. The system is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in multi-tonne time-projection chambers, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined to accommodate the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines.

  16. The dynamic range of LZ

    The electronics of the LZ experiment, the 7-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to permit studies of physics where the energies deposited range from 1 keV of nuclear-recoil energy up to 3,000 keV of electron-recoil energy. The system is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in multi-tonne time-projection chambers, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined to accommodate the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines

  17. Studies on keV and eV electrons in solids

    The interaction between keV or eV electrons and solids was studied. The results presented mostly concern problems in connection with electron irradiation of solids, but to some extent they also include ion-induced secondary electron emission. The experiments were mainly performed on solidified gases using 1 - 3 keV electrons. The projected range of electrons was determined in solid hydrogen, deuterium and nitrogen. The true secondary electron emission coefficient and the electron reflection coefficient of solid hydrogen, deuterium and nitrogen were measured. The escape depth of the true secondary electrons in nitrogen was determined. The angular dependence of both the reflection coefficient and the true secondary electron emission coefficient of solid hydrogen and deuterium was investigated. Both ion- and electron-induced secondary electron emission were treated theoretically on the basis of ionization cascade theory. (Auth.)

  18. Majority-logic NE-110 detector for keV neutrons

    An NE-110 proton-recoil scintillation counter whose efficiency is reproducible and stable has been developed for neutrons in the energy range from 5 keV to 1 MeV. Majority-of-logic at below the single photoelectron level is used between two or more phototubes viewing the same scintillator. Pulse height distributions as a function of neutron energy have been measured between 5 and 350 keV with two different detector configurations: a thin square slab of NE-110 and a cylinder of NE-110. The absolute efficiency of the slab detector has also been determined. The measured results are in good agreement with results from Monte Carlo calculations

  19. Reply to Two Comments on "Dark matter searches going bananas the contribution of Potassium (and Chlorine) to the 3.5 keV line"

    Jeltema, Tesla

    2014-01-01

    We respond to two comments on our recent paper, Jeltema & Profumo (2014). The first comment by Boyarsky et al. confirms the absence of a line from M31 in the 3-4 keV energy range, but criticizes the energy range for spectral fitting on the basis that (i) the background model adopted between 3-4 keV is invalid outside that range and that (ii) extending the energy range multiple features appear, including a 3.5 keV line. Point (i) is manifestly irrelevant (the 3-4 keV background model was not meant to extend outside that range), while closer inspection of point (ii) shows that the detected features are inconsistent and likely unphysical. We demonstrate that the existence of an excess near 3.5 keV in the M31 data requires fitting a broad enough energy range such that the background modeling near 3.5 keV is poor to a level that multiple spurious residual features become significant. Bulbul et al. criticize our use of WebGuide instead of the full AtomDB package. While a technically correct remark, this is only...

  20. Surface exfoliation and defect structures in Si induced by 160 keV He and 110 keV H ion implantation

    Cz n-type Si(100) wafers were implanted at room temperature with 160 keV He ions at a fluence of 5 x 1016/cm2 and 110 keV H ions at a fluence of 1 x 1016/cm2, singly or in combination. Surface phenomena and defect microstructures have been studied by various techniques, including scanning electron microscopy (SEM), atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM). Surface exfoliation and flaking phenomena were only observed on silicon by successive implantation of He and H ions after subsequent annealing at temperatures above 400 deg. C. The surface phenomena show strong dependence on the thermal budget. At annealing temperatures ranging from 500 to 700 deg. C, craters with size of about 10 μm were produced throughout the silicon surface. As increasing temperature to 800 deg. C, most of the implanted layer was sheared, leaving structures like islands on the surface. AFM observations have demonstrated that the implanted layer is mainly transfered at the depth around 960 nm, which is quite consistent with the range of the ions. XTEM observations have revealed that the additional low fluence H ion implantation could significantly influence thermal growth of He-cavities, which gives rise to a monolayer of cavities surrounded by a large amount of dislocations and strain. The surface exfoliation effects have been tentatively interpreted in combination of AFM and XTEM results

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

    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

  2. Electron impact total cross sections for hydrogen molecule from 0.01 eV to 2 keV

    In the present work, we calculate electron impact total cross section for H2 molecule over wide range of incident energies starting from 0.01 eV to 2 keV. The present results are examined as function of incident energies and compared with available results.

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

    Mohan, Harsh, E-mail: mohan_harsh@yahoo.com [Physics Department, M.L.N. College, Yamuna Nagar 135 001, Haryana (India); Jain, Arvind Kumar [Physics Department, M.L.N. College, Yamuna Nagar 135 001, Haryana (India); Kaur, Mandeep [Physics Department, M.L.N. College, Yamuna Nagar 135 001, Haryana (India); Physics Department, Punjabi University, Patiala 147 002, Punjab (India); Singh, Parjit S. [Physics Department, Punjabi University, Patiala 147 002, Punjab (India); Sharma, Sunita [Chemistry Department, M.L.N. College, Yamuna Nagar 135 001, Haryana (India)

    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.

  4. Calculation for Improvement of 350 keV Electron Accelerator

    2011-01-01

    The main problem of the 350 keV electric accelerator is that the accelerator can not output 20 mA for a long time otherwise the vacuum become bad. The reason is that part of the beam bomb on the scanning box and increase the temperature immediately,

  5. KevJumba and the Adolescence of YouTube

    Saul, Roger

    2010-01-01

    This article considers the significance of YouTube as a pedagogical space from which young people can play participatory roles as theorists in their own constructions as popular cultural subjects. Drawing upon the public profile of "KevJumba," a teenager who makes videos of himself on YouTube, the article suggests that representational practices…

  6. Sputtering of solid nitrogen by keV helium ions

    Ellegaard, O.; Schou, Jørgen; Sørensen, H.; Pedrys, R.; Warczak, B.

    Solid nitrogen has become a standard material among the frozen molecular gases for electronic sputtering. We have combined measurements of sputtering yields and energy spectra from nitrogen bombarded by 4-10 keV helium ions. The data show that the erosion is electronic rather than knockon...

  7. Sputtering of solid nitrogen by keV helium ions

    Ellegaard, O.; Schou, Jørgen; Sørensen, H.;

    1993-01-01

    Solid nitrogen has become a standard material among the frozen molecular gases for electronic sputtering. We have combined measurements of sputtering yields and energy spectra from nitrogen bombarded by 4-10 keV helium ions. The data show that the erosion is electronic rather than knockon...

  8. The ASDEX 100 keV neutral lithium beam diagnostic gun

    The neutral lithium beam gun intended for measurement of the poloidal magnetic field and of the density gradient in the scrape-off layer of ASDEX is described, and test results over a beam energy range of 27-100 keV are presented. In the gun, lithium ions are extracted from a solid emitter (#betta#-Eurcryptite) in a Pierce-type configuration, accelerated and focused in a two-tube immersion lens, and neutralized in a charge-exchange cell using sodium. The beam can be pulsed from less than one to several seconds, depending on experimental needs. At a distance of 165 cm from the gun the neutral beam equivalent current is typically greater than 1 mA (0.16 mA) for a beam energy of 100 keV (27 keV), the beam FWHM being about 8-9 mm. It is found that to produce a particular beam with a certain ratio must be maintained between the extraction and total beam voltages, this relationship depending in turn on the emitter-extractor separation. The principal features which distinguish the ASDEX gun from that employed on W7a are the greater compactness - all the active elements, i.e. emitter, extractor, lens, deflection plates and neutralizer, are contained with 57 cm - and the vacuum vessel, which simultaneously serves as the magnetic shielding. (orig.)

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

    Beckmann, V; Shrader, C R; Gehrels, N; Produit, N

    2006-01-01

    We have compiled a complete extragalactic sample based on 25,000 deg^2 to a limiting flux of 3E-11 ergs/cm**2/sec (7,000 deg^2 to a flux limit of 1E-11 ergs/cm**2/sec) in the 20 - 40 keV band with INTEGRAL. We have constructed a detailed exposure map to compensate for effects of non-uniform exposure. The flux-number relation is best described by a power-law with a slope of alpha = 1.66+-0.11. The integration of the cumulative flux per unit area leads to f = 2.6E-10 ergs/cm**2/sec/sr, which is about 1% of the known 20 - 40 keV X-ray background. We present the first luminosity function of AGNs in the 20-40 keV energy range, based on 38 extragalactic objects detected by the imager IBIS/ISGRI on-board INTEGRAL. The luminosity function shows a smoothly connected two power-law form, with an index of gamma_1 = 0.8 below, and gamma_2 = 2.1 above the turn-over luminosity of L* = 2.4E43 ergs/sec. The emissivity of all INTEGRAL AGNs per unit volume is W(> 1E41 ergs/sec) = 2.8E38 ergs/sec/Mpc**3. These results are consis...

  10. The Width of the 511 KeV Line from the Bulge of the Galaxy

    Zhitnitsky, A

    2006-01-01

    This is a comment on a recent criticism by Cumberbatch, Silk and Starkman (CSS), astro-ph/0606429. CSS criticize our proposal suggesting that the 511 keV \\gamma rays from the galactic bulge can be naturally explained by the supermassive Compact Composite Objects (CCO) of dark matter. In this comment I present the detail estimations supporting the original claim that the width of the 511 KeV line produced by such a mechanism is very narrow and in a few KeV range for incoming non relativistic electron with typical velocity v_e\\sim 10^{-3}c. The dominant mechanism of the annihilation in this case is the positronium formation e^+e^-\\to ~ ^1S_0 \\to 2\\gamma rather than a direct e^+e^-\\to 2\\gamma annihilation. This is in contrast with analysis of astro-ph/0606429 where a broad MeV distribution is expected as a result of annihilation within CCO framework. I also discuss some general features of the $\\gamma$ rays spectrum (in few MeV region) resulting from the CCO based mechanism.

  11. The Galactic 511 keV line: analysis and interpretation of Integral observations

    Ever since the discovery of the 511 keV annihilation line emission from the galactic center region in the late seventies, the origin of galactic positrons has been the topic of a vivid scientific debate. It is also one of the prime scientific objectives of the imaging spectrometer SPI on board ESA's INTEGRAL observatory. In this thesis first a description of the most important SPI sub-system is given - the detector plane. Procedures for detector energy calibration and detector degradation analysis are developed. The determination of instrumental background models, a crucial aspect of data analysis, is elaborated. These background models are then applied to deriving sky maps and spectra of unprecedented quality of the Galactic positron annihilation radiation. The emission is centered on the galactic center with a spatial resolution of 8 degrees (FWHM), a second spatial component appears clearly: the galactic disc. The ray energy has been measured with unprecedented accuracy: 511.0 ± 0.03 keV for a full width at half maximum (FWHM) of 2.07 ± 0.1 keV. The total galactic flux ranges from 1.09 to 2.43 10-3 ph.cm-2.s-1 including uncertainties on spatial distribution. Finally, the implications of these observations for the production of positrons by various Galactic populations are discussed

  12. Effective field theory and keV lines from dark matter

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

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

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

  14. Energy dependence of the air kerma response of a liquid ionization chamber at photon energies between 8 keV and 1250 keV

    Full text: In its recent reports on cardiovascular brachytherapy the DGMP recommends the source strength of brachytherapy sources being characterized in terms of absorbed dose to water at a distance of 2 mm from the central axis of the source. As a consequence, the response of a detector suitable for characterizing such sources with respect to absorbed dose to water should depend only to a small extent on radiation energy. Additionally, the detection volume of the detector has to be sufficiently small for the necessary spatial resolution to be obtained. The liquid ionization chamber as described in seems to be a promising means for this type of measurements. The two components of the ionization liquid (TMS and isooctane) can be mixed in a ratio which ensures that the mass-energy absorption coefficient of the resulting mixture deviates from that of water by less than ±15 % down to photon energies of 10 keV. Due to the high density of the ionization medium, the spacing between the two electrodes of the ionization chamber can be made as small as a few tenths of a millimeter and still the resulting ionization current is sufficiently large. The ionization chamber used in the present investigation is a plane parallel chamber 5 mm in diameter and of 0.3 mm electrode spacing. The ionization medium is a mixture of 40 % TMS and 60 % isooctane. The irradiations were carried out with the ISO wide spectra series with tube voltages between 10 kV and 300 kV and with 137Cs and 60Co γ-radiation. As a first step, the response of the liquid ionization chamber was investigated with respect to air kerma instead of absorbed dose to water. Although the mass-energy absorption coefficient of the liquid deviates from that of air by less than ±10 % over the photon energy range, the measured chamber response varies by a factor of about 3.5. Monte Carlo calculations carried out with EGSnrc show a variation of the chamber response smaller than ±20 %. Measurements of the ion yield of the

  15. Formulae for the secondary electron yield and total stopping power from 0.8 keV to 10 keV for metals

    XIE A G; XIAO S Y; WANG L

    2016-05-01

    Based on the range–energy relationship, the characteristics of secondary electron emission, some relationship between the secondary electron yield $\\delta$ and experimental results, the universal formulae for $\\delta_{0.8−2}$ (the subscript indicates that the energy range of primary energy atthe surface W$_{\\rm po}$ is from 0.8 keV to 2 keV) and $\\delta_{2−10}$ for metals were deduced. The $\\delta_{0.8−10}$ calculated with the universal formulae and the$\\delta_{0.8−10}$ measured experimentally were compared, and the scattering of $\\delta$ for the same metal was analysed. Finally, we concluded that the formulae were universal for $\\delta_{0.8−10}$ for metals. On the basis of some relationship between parameters of $\\delta$, wededuce a formula for expressing total stopping power $S_{0.8−10}$ as a function of $S_{10−30}, \\delta_{0.8−10}, \\delta_{10−30}$, backscattered coefficient $\\heta_{0.8−10}, \\heta_{10−30}$ and W$_{\\rm po}. The calculated $S_{0.8−10}$ were compared with the values measured experimentally and it was concluded that the formula to estimate $S_{0.8−10}$ was universal for metals.

  16. Direct elastic and inelastic processes produced in the case of He+-He for 3 KeV00

    The He+ on He collision has been studied by the energy loss method in the 3 to 50 KeV energy range and 0.25 to 30 angle range. A detailed description of the experimental device, which has been built for this purpose, is made. Direct elastic and inelastic cross sections are then obtained by integration. A single theoretical model is given, which explains the main features of the elastic differential cross section behaviour

  17. Computer based diagnostic and control system for a 120 keV neutral beam test stand

    The computer based system provides data acquisition, analysis, display, archival, and control functions for the 120 KEV test stand IIIa at Lawrence Berkeley Laboratory. The system supports calorimeter arrays and spectrometer diagnostics, controls all power supplies and provides 7 modes of control ranging from manual control with computer monitor to full auto conditioning with an auto sweep capability for parameter variation studies. This paper describes the software structure, I/O techniques, control algorithms, hardware configuration, and system performance. Conclusions based on system performance provide useful insight for design of neutral beam control systems for use on large plasma devices

  18. Charge transfer in keV proton collision with atomic oxygen: Differential and total cross sections

    Classical Trajectory Monte Carlo method (CTMC) with the modal interaction potential has been used to simulate the differential, total and partial capture cross sections in proton-oxygen atom collisions in the energy range of 0.5 - 200 keV. An interesting feature of the calculated differential cross sections (DCS) curve below the scattering angle 0.1 degree is the presence of oscillations showing asymmetry in angular positions. The oscillations in the partial cross sections are explained in terms of swapping effect. The DCS and total cross sections are found to be in good agreement with the experimental as well as other theoretical results. (authors)

  19. Erosion of solid neon by keV electrons

    Schou, Jørgen; Børgesen, P.; Ellegaard, Ole;

    1986-01-01

    . The erosion yield increases with increasing temperature for substrate temperatures above 7K. Below this temperature sputtering via electronic transitions is the dominant process. The yield shows a clear minimum for film thicknesses about (5-7)×1016 Ne atoms/cm2 for 2-keV electrons. The sputtering...... yield for thick films has a maximum at 1.2-1.5 keV. The results are explained by the diffusion of excitations to the surface with subsequent decay. From this model and the experimental results one derives a characteristic diffusion length of about 1×1017 Ne atoms/cm2. The eventual particle ejection is...... driven by decay of surface-trapped excitons or by dissociative recombination. The magnitude of the yield indicates that deexciting neon particles at the surface induce further sputtering. Direct sputtering from electron-nucleus collisions does not contribute significantly to the yield...

  20. 17 keV neutrino and majoron models

    In this paper a model for the 17 keV Dirac neutrino is considered in the framework of the SU(2) x U(1) theory. No right-handed neutrinos are introduced. The Dirac mass for the neutrino arises from the Le + Lτ - Lμ invariant couplings of the left-handed neutrinos to an SU(2) triplet. An SU(2) singlet field is introduced to suppress the Majoron coupling to the Z. This makes the model consistent with the LEP results on the invisible Z width. The singlet vacuum expectation value ω is constrained to be ≤ 0(80 MeV) from cosmological considerations. For, ω ∼ 80 MeV, the 17 keV neutrino is shown to provide the bulk of the dark matter

  1. A 600 keV electron radiation accelerator

    The authors describe a 600 keV two-body multi-functional electron and positive ion radiation accelerator based on a 400 keV Cockroft-Walton, Which was successfully used to accelerate electron and positive ion. Through test on coating solidification of decoration materials, such as colorful surface plaster plate and relief plate, and researches on metal plate, plastic plate, wood and paper coating decorations and radiation workmanship, as well as experiment of brach-linking by radiation for filling materials of petroleum pipings, it is proved that the device is reliable and stable in operation and reaches the pre-set design indexes and satisfies the requirements called for

  2. 17-keV neutrino, MSW mechanism, and supernova constraints

    Babu, K. S.; Mohapatra, Rabindra N.; Rothstein, I. Z.

    1992-01-01

    A simple form for the neutrino mass matrix describing νe, νμ, ντ, and a sterile state νs is proposed which accommodates the 17-keV neutrino as a νμ-ντ pseudo Dirac pair and simultaneously resolves the solar-neutrino puzzle via νe-νs Mikheyev-Smirnov-Wolfenstein (MSW) oscillation. This model, which is a specific realization of a scheme proposed recently by Caldwell and Langacker, is automatically free of all supernova constraints. It is shown that the mass matrix follows in a technically natural manner in extensions of the standard model with spontaneously broken global U(1)Le-Lμ×U(1)Lτ symmetry. The 17-keV neutrino decays to νe and a Majoron with a lifetime of order 10-1-10-2 sec thus satisfying all cosmological and astrophysical constraints.

  3. Proximity functions for electrons up to 10 keV

    Chmelevsky, D. (Institut fuer Medizinische Strahlenkunde der Universitaet Wuerzburg, Germany); Kellerer, A.M.; Terrissol, M.; Patau, J.P.

    1980-11-01

    Proximity functions for electrons up to 10 keV in water are computed from simulated particle tracks. Numerical results are given for the differential functions t(x) and the integral functions T(x). Basic characteristics of these functions and their connections to other microdosimetric quantities are considered. As an example of the applicability of the proximity functions, the quantity y/sub D/ for spheres is derived from t(x).

  4. PET surface modification by 0.2 keV and 2.5 keV argon ions

    PET foils have a high potential as a material for biomedical and electrical industries. PET foils were irradiated by ions for variable irradiation time. The effects of low (2.5, 0.2 keV) energy argon ion flux irradiation on the surfaces of polyethylene terephthalate thin foils (PET) were studied. The source of ions was an ECR Ion Gun with settable acceleration voltages. The modified foils were investigated by in-situ X-ray Photoelectron Spectroscopy (XPS) and ex-situ Fourier transform infrared spectroscopy (FTIR). The significant changes in the chemical composition of the surface layer were quantitatively studied by XPS. The scission of the chains in the surface layer of PET foil was induced by ion flux interaction with PET surface. The strong selective sputtering of oxygen atoms in PET film was observed. The atomic ratio O/C was decreased by 0.2keV and 2.5keV argon ion flux from 0.40 to 0.25 and 0.04 respectively. The oxygen atoms in ester bonds are detached first. This phenomenon is responsible for the creation of carbon-rich surface layer. The FTIR analyses identified changes in chemical composition but with no obvious correlation to surface changes. PET volume changes in the spectra were probably results of photons from the ion source influence on PET foils.

  5. Extreme energetic electron fluxes in low Earth orbit: Analysis of POES E > 30, E > 100, and E > 300 keV electrons

    Meredith, Nigel P.; Horne, Richard B.; Isles, John D.; Green, Janet C.

    2016-02-01

    Energetic electrons are an important space weather hazard. Electrons with energies less than about 100 keV cause surface charging, while higher-energy electrons can penetrate materials and cause internal charging. In this study we conduct an extreme value analysis of the maximum 3-hourly flux of E > 30 keV, E > 100 keV, and E > 300 keV electrons in low Earth orbit as a function of L∗, for geomagnetic field lines that map to the outer radiation belt, using data from the National Oceanic and Atmospheric Administration Polar Operational Environmental Satellites (POES) from July 1998 to June 2014. The 1 in 10 year flux of E > 30 keV electrons shows a general increasing trend with distance ranging from 1.8 × 107 cm-2 s-1 sr-1 at L∗=3.0 to 6.6 × 107 cm-2 s-1 sr-1 at L∗=8.0. The 1 in 10 year flux of E > 100 keV electrons peaks at L∗=4.5-5.0 at 1.9 × 107 cm-2 s-1 sr-1 decreasing to minima of 7.1 × 106 and 8.7 × 106 cm-2 s-1 sr-1 at L∗=3.0 and 8.0, respectively. In contrast to the E > 30 keV electrons, the 1 in 10 year flux of E > 300 keV electrons shows a general decreasing trend with distance, ranging from 2.4 × 106 cm-2 s-1 sr-1 at L∗=3.0 to 1.2 × 105 cm-2 s-1 sr-1 at L∗=8.0. Our analysis suggests that there is a limit to the E > 30 keV electrons with an upper bound in the range 5.1 × 107 to 8.8 × 107 cm-2 s-1 sr-1. However, the results suggest that there is no upper bound for the E > 100 keV and E > 300 keV electrons.

  6. Measurement of the neutron capture cross section of the s-only isotope 204Pb from 1 eV to 440 keV

    Domingo-Pardo, C; Aerts, G; Alvarez-Pol, H; Alvarez-Velarde, F; Andriamonje, S; Andrzejewski, J; Assimakopoulos, P; Audouin, L; Badurek, G; Baumann, P; Becvar, F; Berthoumieux, E; Bisterzo, S; Calvino, F; Cano-Ott, D; Capote, R; Carrapico, C; Cennini, P; Chepel, V; Chiaveri, E; Colonna, N; Cortes, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillmann, I; Dolfini, R; Dridi, W; Duran, I; Eleftheriadis, C; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Fitzpatrick, L; Frais-Koelbl, H; Fujii, K; Furman, W; Gallino, R; Goncalves, I; Gonzalez-Romero, E; Goverdovski, A; Gramegna, F; Griesmayer, E; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martinez, A; Igashira, M; Isaev, S; Jericha, E; Kadi, Y; Kappeler, F; Karamanis, D; Karadimos, D; Kerveno, M; Ketlerov, V; Koehler, P; Konovalov, V; Kossionides, E; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Mastinu, P; Mengoni, A; Milazzo, P.M; Moreau, C; Mosconi, M; Neves, F; Oberhummer, H; Oshima, M; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Plag, R; Plompen, A; Plukis, A; Poch, A; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, C; Rudolf, G; Rullhusen, P; Salgado, J; Sarchiapone, L; Savvidis, I; Stephan, C; Tagliente, G; Tain, J.L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarin, D; Vincente, M.C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wendler, H; Wiescher, M; Wisshak, K

    2007-01-01

    The neutron capture cross section of 204Pb has been measured at the CERN n_TOF installation with high resolution in the energy range from 1 eV to 440 keV. An R-matrix analysis of the resolved resonance region, between 1 eV and 100 keV, was carried out using the SAMMY code. In the interval between 100 keV and 440 keV we report the average capture cross section. The background in the entire neutron energy range could be reliably determined from the measurement of a 208Pb sample. Other systematic effects in this measurement could be investigated and precisely corrected by means of detailed Monte Carlo simulations. We obtain a Maxwellian average capture cross section for 204Pb at kT=30 keV of 79(3) mb, in agreement with previous experiments. However our cross section at kT=5 keV is about 35% larger than the values reported so far. The implications of the new cross section for the s-process abundance contributions in the Pb/Bi region are discussed.

  7. Nuclear astrophysics probed by keV neutrons

    Various elements observed in Galaxies can be used as relics to trace the history of the Galaxy after the Big Bang. Light elements up to 7Li were produced during the primordial nucleosynthesis in the early universe and the rest of the observed elements were synthesized in stars through various nuclear reaction processes. By studying the physical conditions of these processes when these light and heavier elements were synthesized, one could construct models about the evolution of stars and stellar nucleosynthesis to be used to trace the history. In this paper we discuss keV neutron induced reactions of nuclei to construct the models. (author)

  8. Combination of resonance integral and Maxwellian 30 keV data – A sensitive test of the resonance region

    Highlights: ► Neutron-induced capture cross sections can be tested by considering the Resonance Integral and Maxwellian average cross section at 30 keV. ► Results are presented for typical reactions from EAF-2010 and ENDF/B-VII.1. ► Including data at the energies of 14.5 MeV and 0.0253 eV as well as the spontaneous fission spectrum of 252-Cf improve the validation process. ► Examples where capture reactions can be improved by this validation procedure are presented. -- Abstract: This paper presents the approach of a combined use of resonance integrals and average Maxwellian cross sections (MACS) at kT = 30 keV to test and validate the resolved resonance range or its reconstructed cross section curve. Based on these two integral measurements a sensitive and energy dependent test can be provided. These two integral quantities cover with their neutron spectra the energy region between En = 0.5 eV up to several hundred keV, respectively, with different weighting. Our principal motivation is to produce a validation tool, sensitive to the lower and upper parts of the resonance region through the difference in the applied 1/E and kT = 30 keV Maxwell–Boltzmann spectra of the resonance integral and MACS data

  9. Electron scattering by Ne, Ar and Kr at intermediate and high energies, 0.5-10 keV

    Semi-empirical total cross sections for electron scattering of noble gases (Ne, Ar and Kr) in the energy range 0.5-10 keV have been obtained by combining transmission-beam measurements for impact energies up to 6 keV with an asymptotic behaviour at higher energies according to the Born-Bethe approximation. The influence of the forward electron scattering on the experimental system has been evaluated by means of a Monte Carlo electron transport simulation. Theoretical values have also been obtained by applying the Born approximation in the case of inelastic processes and by means of an atomic scattering potential for the elastic part. The results of these calculations show an excellent agreement with the semi-empirical values in the above-mentioned energy range. (author)

  10. Electron scattering by Ne, Ar and Kr at intermediate and high energies, 0.5-10 keV

    Garcia, G.; Roteta, M.; Manero, F. [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas (CIEMAT), Departamento de Fusion y Particulas Elementales, Madrid (Spain); Blanco, F. [Universidad Complutense de Madrid, Facultad de Fisica, Departamento de Fisica Atomica Molecular y Nuclear, Madrid (Spain); Williart, A. [Universidad Nacional de Educacion a Distancia, Facultad de Ciencias, Departamento de Fisica de los Materiales, Madrid (Spain)

    1999-04-28

    Semi-empirical total cross sections for electron scattering of noble gases (Ne, Ar and Kr) in the energy range 0.5-10 keV have been obtained by combining transmission-beam measurements for impact energies up to 6 keV with an asymptotic behaviour at higher energies according to the Born-Bethe approximation. The influence of the forward electron scattering on the experimental system has been evaluated by means of a Monte Carlo electron transport simulation. Theoretical values have also been obtained by applying the Born approximation in the case of inelastic processes and by means of an atomic scattering potential for the elastic part. The results of these calculations show an excellent agreement with the semi-empirical values in the above-mentioned energy range. (author)

  11. Sputtering of cryogenic films of hydrogen by keV ions: Thickness dependence and surface morphology

    The sputtering yield induced by keV hydrogen ions measured at CERN and at Riso National Laboratory for solid H2 and D2 at temperatures below 4.2 K decreases with increasing film thickness from about 100 x 1015 molecules/cm2. For a film thickness comparable to or larger than the ion range the data from Riso show a slight increase, whereas the yield from CERN continues to decrease up to very large film thicknesses, i.e. one order of magnitude larger than the ion range. The different behavior of the yield is discussed in terms of the probable growth modes of the films. The films produced at the Riso setup are quench-condensed films, while those produced at CERN are supposed to grow with large hydrogen aggregates on top of a thin bottom layer.

  12. Sputtering of cryogenic films of hydrogen by keV ions: Thickness dependence and surface morphology

    Schou, Jorgen [Department of Photonics Engineering, Riso Campus, Technical University of Denmark, DK-4000 Roskilde (Denmark)], E-mail: j.schou@risoe.dk; Hilleret, Noel [AT-VAC, Cern 1211, CH - Geneva 23 (Switzerland)

    2009-08-15

    The sputtering yield induced by keV hydrogen ions measured at CERN and at Riso National Laboratory for solid H{sub 2} and D{sub 2} at temperatures below 4.2 K decreases with increasing film thickness from about 100 x 10{sup 15} molecules/cm{sup 2}. For a film thickness comparable to or larger than the ion range the data from Riso show a slight increase, whereas the yield from CERN continues to decrease up to very large film thicknesses, i.e. one order of magnitude larger than the ion range. The different behavior of the yield is discussed in terms of the probable growth modes of the films. The films produced at the Riso setup are quench-condensed films, while those produced at CERN are supposed to grow with large hydrogen aggregates on top of a thin bottom layer.

  13. Study of fission product γ spectra in the band 2-500 keV

    In the study of the γ spectrum of uranium fission products, particular attention has been given in this note to the part of the spectrum ranging between 0 and 500 keV after a given pile operating programme and the evolution of this spectrum with time after a pile shutdown has been followed. The study be related to the fission products which appear in the pile as a whole or on those produced in a uranium sample assumed to have been placed in the pile. The latter case has been envisaged here. The spectrum determination is based partly on theory and partly on experiment. The pile operating conditions are different in the two cases, which widens the range of validity of the spectra traced here. (author)

  14. Substorm morphology of >100 keV protons

    The latitudinal morphology of >100 keV protons at different local times has been studied as a function of substorm activity Acharacteristic pattern has been found: During quiet times there is an isotropic zone centered around 670 near midnight, but located on higher latitudes towards dusk and dawn. This zone moves slightly equatorward during the substorm growth phase. During the expansive phase the precipitation spreads poleward apparently to approximately 710 near midnight. The protons are precipitated over a large local time interval on the night side, but the most intense fluxes are found in the pre-midnight sector. A further poleward expansion, to more than 750 near midnight, seems to take place late in the substorm. Away from midnight the expansion reaches even higher latitudes. During the recovery phase the intensity of the expanded region decreases gradually; the poleward boundary is almost stationary if the interplanetary magnetic field has a northward component and no further substorm activity takes place. Mainly protons with energy below approximately 500 keV are precipitated in the expanded region. On the dayside no increase in the precipitation rates is found during substorm expansion, but late in the substorm an enhanced precipitation is found, covering several degrees of latitude. The low-latitude anisotropic precipitation zone is remarkably stable during substorms. A schematic model is presented and discussed in relation to earlier results. (Auth.)

  15. keV Photon Emission from Light Nonthermal Dark Matter

    Allahverdi, Rouzbeh; Gao, Yu

    2014-01-01

    We propose a possible explanation for the recent claim of an excess at 3.5 keV in the X-ray spectrum within a minimal extension of the standard model that explains dark matter and baryon abundance of the universe. The dark matter mass in this model is ${\\cal O}({\\rm GeV})$ and its relic density has a non-thermal origin. The model includes two colored scalars of ${\\cal O}({\\rm TeV})$ mass ($X_{1,2}$), and two singlet fermions that are almost degenerate in mass with the proton ($N_{1,2}$). The heavier fermion $N_2$ undergoes radiative decay to the lighter one $N_1$ that is absolutely stable. Radiative decay with a life time $\\sim 10^{23}$ seconds can account for the claimed 3.5 keV line, which requires couplings $\\sim 10^{-3}-10^{-1}$ between $X_{1,2}, ~ N_{1,2}$ and the up-type quarks. The model also gives rise to potentially detectable monojet, dijet, and monotop signals at the LHC.

  16. Linac4 45 keV Proton Beam Measurements

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

    2013-01-01

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

  17. Formation of submicron scale periodic ripple pattern on Si surface using medium keV Ar-ion beam

    This paper deals with the effect of beam scanning on the wavelength of the ripples and present our recent results of Ar+ bombarded Si in the energy range 50-140 keV. Systematic atomic force microscopy (AFM) characterization of the morphology of the ripple pattern in the above studies shows that with beam scanning the ripple wavelength increases with ion energy and decreases with energy for bombardment without ion beam scanning

  18. A New Observation of the Quiet Sun Soft X-ray (0.5-5 keV) Spectrum

    Caspi, A.; Woods, T. N.; Stone, J.

    2012-12-01

    The solar corona is the brightest source of X-rays in the solar system, and the X-ray emission is highly variable with solar activity. While this is particularly true during solar flares, when emission can be enhanced by many orders of magnitude up to gamma-ray energies, even the so-called "quiet Sun" is bright in soft X-rays (SXRs), as the ~1-2 MK ambient plasma of the corona emits significant thermal bremsstrahlung up to ~5 keV. However, the actual solar SXR (0.5-5 keV) spectrum is not well known, particularly during quiet periods, as, with few exceptions, this energy range has not been systematically studied in many years. Previous observations include ultra-high-resolution but very narrow-band spectra from crystral 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 fair energy resolution (~0.5-0.7 keV FWHM) were made by SphinX on CORONAS-Photon and XRS on MESSENGER, although they did not extend below ~1 keV. We present observations of the quiet Sun SXR emission obtained using a new SXR spectrometer flown on the third SDO/EVE underflight calibration rocket (NASA 36.286). The commercial off-the-shelf Amptek X123 silicon drift detector, with an 8-micron Be window and custom aperture, measured the solar SXR emission from ~0.5 to >10 keV with ~0.15 keV FWHM resolution (though, due to hardware limitations, with only ~0.12 keV binning) and 2-sec cadence over ~5 minutes on 23 June 2012. Despite the rising solar cycle, activity on 23 June 2012 was abnormally low, with no visible active regions and GOES XRS emission near 2010 levels; we measured no solar counts above ~4 keV during the observation period. We compare our X123 measurements with spectra and broadband irradiances from other instruments, including the SphinX observations during the deep solar minimum of 2009, and with upper limits of >3 keV quiet Sun emission

  19. 7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS

    Hofmann, F; Nandra, K; Clerc, N; Gaspari, M

    2016-01-01

    Recently an unidentified emission line at 3.55 keV has been detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV sterile neutrinos, which have been proposed as a dark matter candidate. We aim at putting constraints on the proposed line emission in a large sample of Chandra-observed clusters and obtain limits on the mixing-angle in a 7.1 keV sterile neutrino dark matter scenario. For a sample of 33 high-mass clusters of galaxies we merge all observations from the Chandra data archive. Each cluster has more than 100 ks of combined exposure. The resulting high signal-to-noise spectra are used to constrain the flux of an unidentified line emission at 3.55 keV in the individual spectra and a merged spectrum of all clusters. We obtained very detailed spectra around the 3.55 keV range and limits on an unidentified emission line. Assuming all dark matter were made of 7.1 keV sterile neutrinos the upper limits on the mixing angle are $\\rm{sin^2(2\\Theta...

  20. 7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS

    Hofmann, F.; Sanders, J. S.; Nandra, K.; Clerc, N.; Gaspari, M.

    2016-08-01

    Context. Recently an unidentified emission line at 3.55 keV has been detected in X-ray spectra of clusters of galaxies. The line has been discussed as a possible decay signature of 7.1 keV sterile neutrinos, which have been proposed as a dark matter (DM) candidate. Aims: We aim to put constraints on the proposed line emission in a large sample of Chandra-observed clusters and obtain limits on the mixing angle in a 7.1 keV sterile neutrino DM scenario. Methods: For a sample of 33 high-mass clusters of galaxies, we merge all observations from the Chandra data archive. Each cluster has more than 100 ks of combined exposure. The resulting high signal-to-noise spectra are used to constrain the flux of an unidentified line emission at 3.55 keV in the individual spectra and a merged spectrum of all clusters. Results: We obtained very detailed spectra around the 3.55 keV range and limits on an unidentified emission line. Assuming all DM were made of 7.1 keV sterile neutrinos, the upper limits on the mixing angle are sin2(2Θ) < 10.1×10-11 from ACIS-I and < 40.3×10-11 from ACIS-S data at 99.7 per cent confidence level. Conclusions: We do not find evidence for an unidentified emission line at 3.55 keV. The sample extends the list of objects searched for an emission line at 3.55 keV and will help to identify the best targets for future studies of the potential DM decay line with upcoming X-ray observatories like Hitomi (Astro-H), eROSITA, and Athena.

  1. Radiation blistering in Inconel-625 due to 100 KeV helium ion irradiation

    The objective of this study was to determine whether the change of angle of incidence of an ion beam impinging on surface blisters during their growth phase (before exfoliation) could influence the blister skin thickness and the blister crater depth. Polished, polycrystalline Inconel-625 samples were irradiated at room temperature and at normal incidence to the major sample surface with 100 keV helium ions to a total dose of 6.24x1018 ions/cm2. The results revealed that many exfoliated blisters leave craters which have two or three concentric pits. The blister skin thickness near the center of the blister was found to agree well with the calculated projected range of 100 keV He ions in nickel. However, the blister skin thickness of some exfoliated blisters along the edge of the fracture surface showed different thicknesses. A model is proposed to explain the observed blister crater/blister fracture features in terms of a change of angle of incidence of the incident ions to the surface during the growth phase of surface blisters. (orig.)

  2. Quantitative grating-based X-ray phase contrast tomography at 82 keV

    Grating-based X-ray phase contrast imaging has increasingly aroused interest as the method has been successfully adapted to work with laboratory X-ray sources. The high potential to improve the soft-tissue contrast compared to standard absorption-based tomography and the quantitativeness of the technique have been demonstrated at energies below 35 keV. However, a broad spectrum of applications in industrial testing and medical imaging needs the operation at higher X-ray energies. Technical advances in the grating manufacturing process make it possible to continuously push the existing energy limitations. In this work we report on the results of a first quantitative phase contrast tomography analysis of a high-energy phantom at 82 keV. The phantom consists of well-defined solid materials covering a wide range of densities and atomic numbers and was scanned with high-resolution at a synchrotron radiation source. The absorption and phase contrast images are analyzed in terms of signal-to-noise ratio (SNR), and the material-specific mass absorption coefficients and refractive index decrements are determined and compared to theoretical values.

  3. The Dynamic Range of LZ

    Yin, Jun

    2015-01-01

    The electronics of the LZ experiment, the 7-tonne dark matter detector to be installed at the Sanford Underground Research Facility (SURF), is designed to permit studies of physics where the energies deposited range from 1 keV of nuclear-recoil energy up to 3,000 keV of electron-recoil energy. The system is designed to provide a 70% efficiency for events that produce three photoelectrons in the photomultiplier tubes (PMTs). This corresponds approximately to the lowest energy threshold achievable in such a detector, and drives the noise specifications for the front end. The upper limit of the LZ dynamic range is defined by the electroluminescence (S2) signals. The low-energy channels of the LZ amplifiers provide the dynamic range required for the tritium and krypton calibrations. The high-energy channels provide the dynamic range required to measure the activated Xe lines. S2 signals induced by alpha particles from radon decay will saturate one or more channels of the top PMT array but techniques are being dev...

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

    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 cm2 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. - Highlights: ► Mass attenuation coefficients of various soil and sediment samples have been determined for several gamma lines. ► Mass attenuation coefficients for all types of soil and sediment samples for energy range higher than 165 keV, are similar. ► Fe and Ca in samples have a strong effect on mass attenuation coefficient for energies less than 165 keV.

  5. Underwater Ranging

    S. P. Gaba

    1984-01-01

    Full Text Available The paper deals with underwater laser ranging system, its principle of operation and maximum depth capability. The sources of external noise and methods to improve signal-to-noise ratio are also discussed.

  6. SHEEP the ASCA 5-10 keV survey

    Georgantopoulos, I; Ptak, A

    2001-01-01

    We present the first results of the hard (5-10 keV) ASCA GIS survey SHEEP (Search for the High Energy Extragalactic Population). We have analysed 149 fields covering an area of 39 sq. deg detecting 69 sources. Several of these appear to be associated with QSOs and Seyfert-1 galaxies but with hard X-ray spectra, probably due to high absorption. Indeed, the hardness ratio analysis shows that the spectra of the majority of our sources can be represented with a ``scatterer'' model similar to obscured Seyfert galaxies locally. According to this model, our sources present high intrinsic absorption (logN_H~23) but also significant amounts of soft X-ray emission coming from scattered light.

  7. RF control system for 400 keV RFQ

    An RF control system has been developed for the 400 keV, 350 MHz RFQ coming up at BARC. This single cavity system consists of the functionalities of amplitude stabilization and frequency tracking for both continuous and pulsed mode of operation. The amplitude stabilization is implemented by modulating the attenuation across a fast modulator placed in the drive path. The frequency tracking is achieved by driving the FM port of a signal generator with a signal proportional to the phase shift across the resonator. The whole system is under computer control via CAMAC hardware. The paper describes the system architecture, housing and wiring of the system in a single instrumentation rack and development and testing of computer control. (author)

  8. Contribution to the study of nuclear structure using neutron total cross-section measurements between 400 and 1200 keV: isolated resonances and intermediate structure

    The neutron total cross sections have been measured over the energy range 400 keV - 1200 keV for fluorine, aluminium, silicon, phosphorus, vanadium, chromium, manganese, iron, nickel, cobalt and lead with an energy spread of 3 keV. The neutrons were produced by the T (p,n) 3He reaction, the proton beam was supplied by a 2 MeV Van de Graaff. The structure in 56Fe has been studied in a more detailed way by measuring six angular distributions in the above range and the elastic scattering excitation curves at four angles. The measurements have made it possible to show the existence of the compound nucleus, as well as the presence of an intermediate structure in certain nuclei. (author)

  9. Dark matter searches going bananas: the contribution of Potassium (and Chlorine) to the 3.5 keV line

    Jeltema, Tesla E

    2014-01-01

    We examine the claimed excess X-ray line emission near 3.5 keV with a new analysis of XMM-Newton observations of the Milky Way center and with a re-analysis of the data on M31 and clusters. In no case do we find conclusive evidence for an excess. We show that known plasma lines, including in particular K XVIII lines at 3.48 and 3.52 keV, provide a satisfactory fit to the XMM data from the Galactic center. We assess the expected flux for the K XVIII lines and find that the measured line flux falls squarely within the predicted range based on the brightness of other well-measured lines in the energy range of interest. We then re-evaluate the evidence for excess emission from clusters of galaxies, including a previously unaccounted for Cl XVII line at 3.51 keV, and allowing for systematic uncertainty in the expected flux from known plasma lines and for additional uncertainty due to potential variation in the abundances of different elements. We find that no conclusive excess line emission is present within the s...

  10. Measurement 20-200 keV hard X-ray based on CdTe detector in EAST Tokamak

    Background: Accurate and quantitative measurement of plasma radiation is a key issue to Tokamak, toroidal magnetic confinement device. The radiations from Tokamak cover large energy range. Driven by the determination of the obtaining of hard X-ray spectra, a new system based on a high performance CdTe detector was built up in EAST Tokamak, the first non-circle cross-section in the world. Purpose: Introduces the device of hard X-ray diagnosis system in the EAST Tokamak on the Port A. The system can measure the plasma hard X-ray (20-200 keV) spectra under different discharge conditions, including Ohmical shot and Lower Hybrid Current Drive (LHCD) shot. The research of high speed electron which produced by LHCD is also the aim of the new system. Methods: A high performance CdTe detector was using in EAST Tokamak to measure the hard X-ray (20-200 keV) spectra. Results: The results show that the new system based on a high performance CdTe can meet the requirements for measuring the EAST Tokamak. Conclusions: A preliminary experimental result showed that the system can meet the requirements for measuring the X-ray bremsstrahlung of plasma in the energy range from 20 to 200 keV Calibration result and typical measurement result on EAST are present in this paper. (authors)

  11. A measuring method of photo-electric cross section. Application to high-Z elements between 40 keV and 220 keV. Measurement of K absorption edge energy of Au, Th, U, Pu

    This study first describes a bent crystal monochromator developed for the production of monochromatic beams in a continuous energy range from 30 to 250 keV; it is completed by a metrological application of the device (determination of K absorption edge energy of Au, Th, U, Pu). A method and the associated experimental procedure were developed to measure the photo-electric cross section for high-Z elements; the results are presented with a relative uncertainty ranging between 3 and 6%. Finally, the experimental values are compared with values calculated from theories using self-consistent potential models

  12. New generation of efficient high resolution detector for 30-100 keV photons

    Olsen, Ulrik Lund

    For direct space X-ray imaging with an intrinsic spatial resolution of less than 10 µm scintillating detectors is used almost universally. The spatial resolution is limited by the thickness of the scintillator and by the numerical aperture of the optical connection between scintillator and photo...... detector. This establishes an inverse correlation between the spatial resolution and the detection efficiency which limits the performance of existing x-ray detectors. The purpose of this Ph.D. project is to explore alternative paths of research, to develop x-ray detectors for the 30-100 keV energy range...... of a silicon matrix of holes filled with the phosphor material, CsI:Tl. The generated luminescence of the phosphor is guided by the silicon structure through total internal reflection. The spatial resolution of the scintillator is given by the size of the holes which is fabricated down to a distance of 1 µm...

  13. Development of a keV single-ion-implanter for nanofabrication

    Traditional methods of doping semiconductors have a difficulty meeting the demand for high precision doping due to large statistical fluctuations in the numbers of dopant atoms introduced in the ever shrinking volume in micro- and nano-electronics devices, especially when the fabrication process approaches the nanometre scale. The statistical fluctuations in doping semiconductors for the fabrication of devices with a very small feature size may lead to inconsistent and unreliable performance. This paper describes the adaptation of a commercial ion implanter into a single-ion-implantation system for the accurate delivery of dopants into a nanometre or micrometre area in a silicon substrate. All the implanted ions can be accurately counted with near 100% certainty through online detection using the silicon substrate itself as an ion detector. A variety of ion species including B+, N+, P+ at the energy range of 10-15 keV can be delivered in the single ion implantation system. (author). 6 refs., 6 figs

  14. 15 keV N+ implantation to induce mutation of protopectinase-producing Aspergillus sp

    Protopectinase will be of potential use in industry. The strain of protopectinase-producing Aspergillus sp. XZ-131 was mutagenized by 15 keV N+ ion implantation, with a dose range of 0.52 x 1015 ion/cm2 to 4.68 x 1015 ion/cm2. From the ion implanted Aspergillus sp. XZ-131, the Strain Z-25, which yields high activity protopectinase, was screened out. The protopectinase activity increased by 179% and the protopectinase (U/g dry cell) increased by 84%. In addition, the exponential phase of Aspergillus sp. Z-25 was 24 hours shorter than the Strain XZ-131. The Aspergillus sp. Z-25 yielded high protopectinase activity during stationary phase, the highest protopectinase activity was achieved after 72 h fermentation. (authors)

  15. 150 keV accelerator as pulsed neutron source; Acelerador de 150 keV como fuente de neutrones pulsada

    Cordero, F.

    1970-07-01

    The project of a 150 keV Cockcroft-Walton accelerator built at J.E.N. is described. Beam currents of more than 10 mA, with a neutron intensity of 10{sup 1}1 n.s{sup 1}, are obtained. Also, we report some research made in connection with that project. The role of the contamination in the vacuum system and the performance of the pumps and gauges pumping deuterium gas are studied. Sinusoidal pulses are employed as an analysis method of the discharge in the ion source and the performance of the extracting-focusing system. The parameters of the beam leaving the ion source have been determined; these are used to calculate the electrostatic lenses with the gaussian optics. Measurements concerning deuterium and tritium targets as neutron sources have been made and the processes affecting their practical service life are analyzed. (Author) 71 refs.

  16. Anisotropic pitch angle distribution of ~100 keV microburst electrons in the loss cone: measurements from STSAT-1

    J. J. Lee

    2012-11-01

    Full Text Available Electron microburst energy spectra in the range of 170 keV to 360 keV have been measured using two solid-state detectors onboard the low-altitude (680 km, polar-orbiting Korean STSAT-1 (Science and Technology SATellite-1. Applying a unique capability of the spacecraft attitude control system, microburst energy spectra have been accurately resolved into two components: perpendicular to and parallel to the geomagnetic field direction. The former measures trapped electrons and the latter those electrons with pitch angles in the loss cone and precipitating into atmosphere. It is found that the perpendicular component energy spectra are harder than the parallel component and the loss cone is not completely filled by the electrons in the energy range of 170 keV to 360 keV. These results have been modeled assuming a wave-particle cyclotron resonance mechanism, where higher energy electrons travelling within a magnetic flux tube interact with whistler mode waves at higher latitudes (lower altitudes. Our results suggest that because higher energy (relativistic microbursts do not fill the loss cone completely, only a small portion of electrons is able to reach low altitude (~100 km atmosphere. Thus assuming that low energy microbursts and relativistic microbursts are created by cyclotron resonance with chorus elements (but at different locations, the low energy portion of the microburst spectrum will dominate at low altitudes. This explains why relativistic microbursts have not been observed by balloon experiments, which typically float at altitudes of ~30 km and measure only X-ray flux produced by collisions between neutral atmospheric particles and precipitating electrons.

  17. QUIET-TIME INTERPLANETARY {approx}2-20 keV SUPERHALO ELECTRONS AT SOLAR MINIMUM

    Wang, Linghua [Department of Geophysics, Peking University, 100871 Beijing (China); Lin, Robert P.; Salem, Chadi; Pulupa, Marc; Larson, Davin E.; Luhmann, Janet G. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States); Yoon, Peter H., E-mail: wanglhwang@gmail.com [School of Space Research, Kyung Hee University, Yongin, Gyeonggi (Korea, Republic of)

    2012-07-01

    We present a statistical survey of {approx}2-20 keV superhalo electrons in the solar wind measured by the SupraThermal Electron instrument on board the two STEREO spacecraft during quiet-time periods from 2007 March through 2009 March at solar minimum. The observed superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f{proportional_to}v{sup -{gamma}}, with {gamma} ranging from 5 to 8.7, with nearly half between 6.5 and 7.5, and an average index of 6.69 {+-} 0.90. The observed power-law spectrum varies significantly on a spatial scale of {approx}>0.1 AU and a temporal scale of {approx}>several days. The integrated density of quiet-time superhalo electrons at 2-20 keV ranges from {approx}10{sup -8} cm{sup -3} to 10{sup -6} cm{sup -3}, about 10{sup -9}-10{sup -6} of the solar wind density, and, as well as the power-law spectrum, shows no correlation with solar wind proton density, velocity, or temperature. The density of superhalo electrons appears to show a solar-cycle variation at solar minimum, while the power-law spectral index {gamma} has no solar-cycle variation. These quiet-time superhalo electrons are present even in the absence of any solar activity-e.g., active regions, flares or microflares, type III radio bursts, etc.-suggesting that they may be accelerated by processes such as resonant wave-particle interactions in the interplanetary medium, or possibly by nonthermal processes related to the acceleration of the solar wind such as nanoflares, or by acceleration at the CIR forward shocks.

  18. Photon production from collisions of 100--350-keV positive ions with CO, CF4, and CH4

    Various photon emissions from collisions of H+, H2+, and He+ in the 100--350-keV energy range with targets of CO, CF4, and CH4 were studied. The wavelength range of the investigation ran from 2000 to 7000 A. Photon-emission cross sections were measured for all significant features. The cross-section data were compared to the Bethe-Born theory through the use of Fano plots. The results show that the theory could be applicable in the case of the CO target, but is probably not applicable to the tetrahedral molecular targets as the emissions are from dissociated atoms

  19. Atomic scattering in the diffraction limit: electron transfer in keV Li+-Na(3s, 3p) collisions

    Poel, Mike van der; Nielsen, C.V.; Rybaltover, M.;

    2002-01-01

    We measure angle differential cross sections (DCS) in Li+ + Na --> Li + Na+ electron transfer collisions in the 2.7-24 keV energy range. We do this with a newly constructed apparatus which combines the experimental technique of cold target recoil ion momentum spectroscopy with a laser-cooled target...... quantum scattering amplitudes are derived by the eikonal method. The resulting angle-differential electron transfer cross sections and their diffraction patterns agree with the experimental level-to-level results over most scattering angles in the energy range....

  20. Creation of 2-5 keV and 5-10 keV sky maps using XMM-Newton data

    Savchenko, Denis

    2014-01-01

    Sky maps are powerful visualisation tools for quicklook analysis of extended sources. The latest sky map in soft X-rays (0.1-2.4 keV) has been created in 90ies using ROSAT data. By analyzing publically available data from XMM-Newton X-ray mission we constructed new sky maps in two energy bands -- 2-5 keV and 5-10 keV, complementary to ROSAT data, covering about 1% of all sky, and included them to our web-based tool http://skyview.virgoua.org.

  1. Checking the potassium origin of the new emission line at 3.5 keV using the K XIX line complex at 3.7 keV

    Iakubovskyi, Dmytro

    2015-11-01

    It is currently unclear whether the new line at ˜3.5 keV, recently detected in various samples of galaxy clusters, the Andromeda galaxy and the central part of our Galaxy, is caused by potassium emission lines. By using the latest astrophysical atomic emission line data base, AtomDB v. 3.0.2, we show that the most promising method to check its potassium origin directly will be the study of the K XIX emission line complex at ˜3.7 keV using forthcoming X-ray imaging spectrometers such as the Soft X-ray spectometer onboard the Astro-H mission or the microcalorimeter onboard the Micro-X sounding rocket experiment. In order to further reduce the remaining (factor of ˜3-5) uncertainty of the 3.7/3.5 keV ratio, more precise modelling should be performed, including the removal of significant spatial inhomogeneities, a detailed treatment of background components, and the extension of the modelled energy range.

  2. Extra light fermions in E6-inspired models and the 3.5 keV X-ray line signal

    We propose a scenario in which extra light fermions in an E6-inspired U(1) extension of the standard model constitute the dark matter, as a simple variation of our model for dark radiation presented in 2010. Interestingly, for the light fermions of mass about 7 keV, we naturally obtain a desired mixing angle to explain the recently discovered 3.5 keV X-ray line signal through the radiative decay into active neutrinos and photons with a lifetime in the range of 1027–1028 seconds

  3. Deep XMM Observations of Draco rule out at the 99% Confidence Level a Dark Matter Decay Origin for the 3.5 keV Line

    Jeltema, TE; Profumo, S.

    2016-01-01

    We searched for an X-ray line at energies around 3.5 keV in deep, ~1.6 Msec XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found in either the MOS or the PN detectors. The data in this energy range are completely consistent with a single, unfolded power law modeling the particle background, which dominates at these energies, plus instrumental lines; the addition of a ~3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flu...

  4. Extra light fermions in $E_6$-inspired models and the 3.5 keV X-ray line signal

    Nakayama, Kazunori; Yanagida, Tsutomu T

    2014-01-01

    We propose a scenario in which extra light fermions in an $E_6$-inspired U(1) extension of the standard model constitute the dark matter, as a simple variation of our model for dark radiation presented in 2010. Interestingly, for the light fermions of mass about 7 keV, they radiatively decay into active neutrinos and photons with a lifetime in the range of $10^{27}-10^{28}$ seconds, which naturally explains the recently discovered 3.5 keV X-ray line signal.

  5. Deep XMM observations of Draco rule out at the 99 per cent confidence level a dark matter decay origin for the 3.5 keV line

    Jeltema, T; Profumo, S.

    2016-01-01

    We searched for an X-ray line at energies around 3.5 keV in deep, ~1.6 Msec XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found in either the MOS or the PN detectors. The data in this energy range are completely consistent with a single, unfolded power law modeling the particle background, which dominates at these energies, plus instrumental lines; the addition of a ~3.5 keV line feature gives no improvement to the fit. The corresponding upper lim...

  6. Semi-empirical method for self-absorption correction of photons with energies as low as 10 keV in environmental samples

    A semi-empirical method that allows the correction of photon self-absorption in gamma spectrometry of environmental matrices is presented. Both, photon transmittance and photopeak efficiency are calculated for energies above 10 keV for any given composition with the help of a Monte Carlo simulation especially developed for this purpose. The simulation is validated for various sample-detector geometries. Problems related to sample composition are discussed with a special focus on the lowest range of energy (13-80 keV)

  7. Searching for the 3.5 keV Line in the Stacked Suzaku Observations of Galaxy Clusters

    Bulbul, Esra; Foster, Adam; Miller, Eric; Bautz, Mark; Loewenstein, Mike; Randall, Scott W; Smith, Randall K

    2016-01-01

    We perform a detailed study of the stacked Suzaku observations of 47 galaxy clusters, spanning a redshift range of 0.01-0.45, to search for the unidentified 3.5 keV line. This sample provides an independent test for the previously detected line. We detect only a 2sigma-significant spectral feature at 3.5 keV in the spectrum of the full sample. When the sample is divided into two subsamples (cool-core and non-cool core clusters), cool-core subsample shows no statistically significant positive residuals at the line energy. A very weak (2sigma-confidence) spectral feature at 3.5 keV is permitted by the data from the non-cool core clusters sample. The upper limit on a neutrino decay mixing angle from the full Suzaku sample is consistent with the previous detections in the stacked XMM-Newton sample of galaxy clusters (which had a higher statistical sensitivity to faint lines), M31, and Galactic Center at a 90% confidence level. However, the constraint from the present sample, which does not include the Perseus clu...

  8. First Results from Fermi GBM Earth Occultation Monitoring: Observations of Soft Gamma-Ray Sources Above 100 keV

    Case, Gary L; Rodi, James C; Jenke, Peter; Wilson-Hodge, Colleen A; Finger, Mark H; Meegan, Charles A; Camero-Arranz, Ascencion; Beklen, Elif; Bhat, P Narayan; Briggs, Michael S; Chaplin, Vandiver; Connaughton, Valerie; Paciesas, William S; Preece, Robert; Kippen, R Marc; von Kienlin, Andreas; Griener, Jochen

    2010-01-01

    The NaI and BGO detectors on the Gamma-ray Burst Monitor (GBM) on Fermi are now being used for long-term monitoring of the hard X-ray/low energy gamma-ray sky. Using the Earth occultation technique as demonstrated previously by the BATSE instrument on the Compton Gamma-Ray Observatory, GBM can be used to produce multiband light curves and spectra for known sources and transient outbursts in the 8 keV to 1 MeV energy range with its NaI detectors and up to 40 MeV with its BGO detectors. Over 85% of the sky is viewed every orbit, and the precession of the Fermi orbit allows the entire sky to be viewed every ~26 days with sensitivity exceeding that of BATSE at energies below ~25 keV and above ~1.5 MeV. We briefly describe the technique and present preliminary results using the NaI detectors after the first two years of observations at energies above 100 keV. Eight sources are detected with a significance greater than 7 sigma: the Crab, Cyg X-1, SWIFT J1753.5-0127, 1E 1740-29, Cen A, GRS 1915+105, and the transien...

  9. New Observations of the Solar 0.5-5 keV Soft X-ray Spectrum

    Caspi, Amir; Warren, Harry P

    2015-01-01

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ~0.2 and ~4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially-integrated solar spectral irradiance from ~0.5 to ~5 keV, with ~0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5-10 MK) emission and are well fit by simple power-law temperature distributions with indices of ~6, ...

  10. The 5 - 10 keV AGN luminosity function at 0.01

    Fotopoulou, S; Georgantopoulos, I; Hasinger, G; Salvato, M; Georgakakis, A; Cappelluti, N; Ranalli, P; Hsu, L T; Brusa, M; Comastri, A; Miyaji, T; Nandra, K; Aird, J; Paltani, S

    2016-01-01

    The active galactic nuclei X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the active galactic nuclei (AGN) population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH=10^23 cm^-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01

  11. Metastable dark matter mechanisms for INTEGRAL 511 keV $\\gamma$ rays and DAMA/CoGeNT events

    Cline, James M; Chen, Fang

    2010-01-01

    We explore dark matter mechanisms that can simultaneously explain the galactic 511 keV gamma rays observed by INTEGRAL/SPI, the DAMA/LIBRA annual modulation, and the excess of low-recoil dark matter candidates observed by CoGeNT. It requires three nearly degenerate states of dark matter in the 4-7 GeV mass range, with splittings respectively of order an MeV and a few keV. The top two states have the small mass gap and transitions between them, either exothermic or endothermic, can account for direct detections. Decays from one of the top states to the ground state produce low-energy positrons in the galaxy whose associated 511 keV gamma rays are seen by INTEGRAL. This decay can happen spontaneously, if the excited state is metastable (longer-lived than the age of the universe), or it can be triggered by inelastic scattering of the metastable states into the shorter-lived ones. We focus on a simple model where the DM is a triplet of an SU(2) hidden sector gauge symmetry, broken at the scale of a few GeV, givin...

  12. Deep XMM observations of Draco rule out at the 99 per cent confidence level a dark matter decay origin for the 3.5 keV line

    Jeltema, Tesla; Profumo, Stefano

    2016-06-01

    We searched for an X-ray line at energies around 3.5 keV in deep, ˜1.6 Ms XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found in either the Metal Oxide Semi-conductor (MOS) or the p-type/n-type semiconductor (PN) detectors. The data in this energy range are completely consistent with a single, unfolded power-law modelling the particle background, which dominates at these energies, plus instrumental lines; the addition of a ˜3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flux rules out a dark matter decay origin for the 3.5 keV line found in observations of clusters of galaxies and in the Galactic Centre at greater than 99 per cent confidence level.

  13. Deep XMM Observations of Draco rule out a dark matter decay origin for the 3.5 keV line

    Jeltema, Tesla E

    2015-01-01

    We searched for an X-ray line at energies around 3.5 keV in deep, ~1.6 Msec XMM-Newton observations of the dwarf spheroidal galaxy Draco. No line was found. The data in this energy range are completely consistent with a simple power law X-ray background, dominated by particle background, plus instrumental lines; the addition of a ~3.5 keV line feature gives no improvement to the fit. The corresponding upper limit on the line flux rules out a dark matter decay origin for the 3.5 keV line found in observations of clusters of galaxies and in the Galactic Center at greater than 99% C.L..

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

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

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

    A measurement of the 238U neutron capture yield was performed at the 150 meter flight-path of the ORELA facility on two 238U samples (0.0124 and 0.0031 atoms/barn). The capture yield data were normalized by Moxon's small resonance method. The energy resolution achieved in this measurement frequently resulted in doublet and triplet splittings of what appeared to be single resonances in previous measurements. This resolution should allow extension of the resolved resonance energy region in 238U from the present 4-keV limit up to 15 or 20 keV incident neutron energy. Some 200 small resonances of the (238U + n) compound nucleus have been observed which had not been detected in transmission measurements, in the energy range from 250 eV to 10 keV. (author)

  16. The 5-10 keV AGN luminosity function at 0.01 < z < 4.0

    Fotopoulou, S.; Buchner, J.; Georgantopoulos, I.; Hasinger, G.; Salvato, M.; Georgakakis, A.; Cappelluti, N.; Ranalli, P.; Hsu, L. T.; Brusa, M.; Comastri, A.; Miyaji, T.; Nandra, K.; Aird, J.; Paltani, S.

    2016-03-01

    The active galactic nuclei (AGN) X-ray luminosity function traces actively accreting supermassive black holes and is essential for the study of the properties of the AGN population, black hole evolution, and galaxy-black hole coevolution. Up to now, the AGN luminosity function has been estimated several times in soft (0.5-2 keV) and hard X-rays (2-10 keV). AGN selection in these energy ranges often suffers from identification and redshift incompleteness and, at the same time, photoelectric absorption can obscure a significant amount of the X-ray radiation. We estimate the evolution of the luminosity function in the 5-10 keV band, where we effectively avoid the absorbed part of the spectrum, rendering absorption corrections unnecessary up to NH ~ 1023 cm-2. Our dataset is a compilation of six wide, and deep fields: MAXI, HBSS, XMM-COSMOS, Lockman Hole, XMM-CDFS, AEGIS-XD, Chandra-COSMOS, and Chandra-CDFS. This extensive sample of ~1110 AGN (0.01 separately for each survey and for the combined sample. We show that, according to Bayesian model selection, the preferred model for our dataset is the LDDE. Our estimation of the AGN luminosity function does not require any assumption on the AGN absorption and is in good agreement with previous works in the 2-10 keV energy band based on X-ray hardness ratios to model the absorption in AGN up to redshift three. Our sample does not show evidence of a rapid decline of the AGN luminosity function up to redshift four.

  17. Simultaneous observations of energetic (keV) upstreaming and electrostatic hydrogen cyclotron waves

    A comparative study of upstreaming energetic ions in the kilovolt energy range and electrostatic hydrogen cyclotron (EHC) waves has been made using the ion mass spectrometer and plasma wave receiver data sets for the first 1200 orbits of the S3-3 spacecraft. The pustreaming energetic ions and EHC waves are found to coincide in over 90% of the events studied. In addition, both EHC waves and upstreaming ions with energies greater than 500 eV exhibit a lower border in their altitude distribution near 5000 km. The nearly exact correlation suggests either than the upstreaming ions are producing the EHC waves or that the EHC waves are heating the ions. One example of EHC waves and upstreaming energetic ions is analyzed to test the two hypotheses. Evidence that EHC waves are heating ions is presented in the form of conic ion distributions which some theories predict are the consequence of this process. Perpendicular ion heating to at least 6 keV is found to coincide with EHC waves. Evidence that the upstreaming ions are the source of free energy for the EHC waves is presented in the form of an ion distribution function with partialf/partialv>0. However, the stability of that ion distribution function is considered and found to be stable unless other conditions such as filamentation or electron drift are invoked. There also exists the possibility that the source of free energy for EHC waves is drifting thermal electrons. For the one example studied the drifting electron process is consistent with data from the S3-3 magnetometer. However, it is inconsistent with the S3-3 electron spectrometer which indicates that the current is carried by keV electrons, not thermal electrons. Consequently, the source of free energy for EHC waves is not yet unambiguously determined

  18. SURVIVAL DEPTH OF ORGANICS IN ICES UNDER LOW-ENERGY ELECTRON RADIATION ({<=}2 keV)

    Barnett, Irene Li; Lignell, Antti; Gudipati, Murthy S., E-mail: gudipati@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, Mail Stop 183-301, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)

    2012-03-01

    Icy surfaces in our solar system are continually modified and sputtered with electrons, ions, and photons from solar wind, cosmic rays, and local magnetospheres in the cases of Jovian and Saturnian satellites. In addition to their prevalence, electrons specifically are expected to be a principal radiolytic agent on these satellites. Among energetic particles (electrons and ions), electrons penetrate by far the deepest into the ice and could cause damage to organic material of possible prebiotic and even biological importance. To determine if organic matter could survive and be detected through remote sensing or in situ explorations on these surfaces, such as water ice-rich Europa, it is important to obtain accurate data quantifying electron-induced chemistry and damage depths of organics at varying incident electron energies. Experiments reported here address the quantification issue at lower electron energies (100 eV-2 keV) through rigorous laboratory data analysis obtained using a novel methodology. A polycyclic aromatic hydrocarbon molecule, pyrene, embedded in amorphous water ice films of controlled thicknesses served as an organic probe. UV-VIS spectroscopic measurements enabled quantitative assessment of organic matter survival depths in water ice. Eight ices of various thicknesses were studied to determine damage depths more accurately. The electron damage depths were found to be linear, approximately 110 nm keV{sup -1}, in the tested range which is noticeably higher than predictions by Monte Carlo simulations by up to 100%. We conclude that computational simulations underestimate electron damage depths in the energy region {<=}2 keV. If this trend holds at higher electron energies as well, present models utilizing radiation-induced organic chemistry in icy solar system bodies need to be revisited. For interstellar ices of a few micron thicknesses, we conclude that low-energy electrons generated through photoionization processes in the interstellar medium

  19. Development status of 200 KeV, linear induction accelerator

    Full text: The Linear Induction Accelerator is being constructed for research and applications of high energy beams with high repetition rate. This paper presents the status of 200 keV, 5 kA, 50 ns, 10 Hz-100 Hz Linear Induction Accelerator (LIA) project undertaken by us. The main challenges involved in this project are development of (i) high power switching modules, (ii) pulse transformer with minimal leakage inductance and (iii) magnetic switches iv) induction cavities. Our scheme starts with a low voltage high current DC system charging a capacitor followed by a chain of compression stages and voltage step-up. The 2.5kV : 20kV first stage pulse transformer with built-in reset arrangement has been designed and fabricated with 6-toroidal amorphous cores of size 160/240/25mm. The total leakage inductance could be minimized to 3.5mH. The coaxially designed next stage pulse compression module has been fabricated and tested for full ratings. Water capacitors have been designed for energy storage at subsequent microsecond time scales. Provided with demineralised water circulation and adequate mechanical support, they are currently under fabrication. A 2.5 W water pulse- forming line (PFL) with water-oil interface is also designed to realize a pulse of 50 ns duration across a matched load with minimum distortion. The PFL is connected to the three induction cavities in parallel by a single output switch and three parallel bunches of cable with 100 kV insulation ratings providing an effective characteristic impedance of 2.5 W. Prototype induction cavities using amorphous cores at 20 kV voltage level have been operated in the adder mode. The graphite field emission diode is connected at the output of the adder consisting of three 75 kV induction modules offering a reflected impedance which matches with that of the PFL

  20. Experimental measurement of effective atomic number of composite materials for Compton effect in the -ray region 280–1115 keV by a new method

    S Prasanna Kumar; T K Umesh

    2011-08-01

    In this paper, we report a new method to determine the effective atomic number, eff, of composite materials for Compton effect in the γ -ray region 280–1115 keV based on the theoretically obtained Klein–Nishina scattering cross-sections in the angular range 50°–100° as well as a method to experimentally measure differential incoherent (Compton) scattering cross-sections in this angular range. The method was employed to evaluate eff for different inorganic compounds containing elements in the range = 1–56, at three scattering angles 60°, 80° and 100° at three incident gamma energies 279.1 keV, 661.6 keV and 1115.5 keV and we have verified this method to be an appropriate method. Interestingly, the eff values so obtained for the inorganic compounds were found to be equal to the total number of electrons present in the sample as given by the atomic number of the elements constituting the sample in accordance with the chemical formula of the sample. This was the case at all the three energies.

  1. Mechanical design and construction of a 200 mA, 100 keV, dc, negative ion accelerator

    A volume production source and a 100 keV, dc, accelerator together with an additional, modular, 100 keV, electro static focused accelerator provide a starting point for a high energy H-/D- beam-line (200 keV to 800 keV), intended for fusion energy applications. The 100 keV accelerator tests started in June 1987. The mechanical design and construction of the accelerator is described. 3 refs., 8 figs

  2. Optical excitation function of H(1s-2p) produced by electron impact from threshold to 1.8 keV

    The optical excitation function of prompt Lyman-α radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet monochromator system was used to measure the emitted Lyman-α radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Our data are significantly different from the earlier experimental results and which are limited to energies below 200 eV. Statistical and known systematic uncertainties in our data range from ±4% near threshold to ±2% at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close-coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10% level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7% of the CCC calculations over the 14 eV endash 1.8 keV range. The present CCC calculations converge on the Bethe-Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3% is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV endash 1.8 keV energy range. (Abstract Truncated)

  3. What can BeppoSAX do about the 2-10 keV cosmic background ? A progress report

    Chiappetti, L; Del Sordo, S; Maccarone, M C; Mineo, T; Molendi, S

    1997-01-01

    We report the current status of the analysis of the MECS background using the entire dataset of the BeppoSAX Science performance Verification Phase. We have collected 360 ks of dark Earth instrumental background, 470 ks of bright Earth background and 1100 ks of blank field data. We are attempting to model the instrumental background in terms of its various components (in particular the spatial modulation of the residual contamination by the built-in Fe calibration sources), and then use this model, and the information on the vignetting and the PSF to derive the cosmic background in the 2-10 keV range

  4. Preliminary measurements of doubly differential cross sections for ejection of electrons from atomic hydrogen by 70 keV protons

    A Slevin atomic hydrogen source has been used to produce a thermal beam of H and H2 as a target for 70 keV protons. A method has been devised which yields atomic to molecular hydrogen cross section ratios. Since the electron ejection cross sections for H2 are known, the atomic hydrogen cross sections can be determined. The angular and energy ranges of the detected electrons, differential in angle and energy, are 20 degrees-160 degrees and 1.5-250 eV respectively

  5. Preliminary measurements of doubly differential cross sections for ejection of electrons from atomic hydrogen by 70 keV protons

    Kerby, G.W.; Gealy, M.W.; Hsu, Y.Y.; Rudd, M.E. [Univ. of Nebraska, Lincoln, NB (United States)

    1993-05-01

    A Slevin atomic hydrogen source has been used to produce a thermal beam of H and H{sub 2} as a target for 70 keV protons. A method has been devised which yields atomic to molecular hydrogen cross section ratios. Since the electron ejection cross sections for H{sub 2} are known, the atomic hydrogen cross sections can be determined. The angular and energy ranges of the detected electrons, differential in angle and energy, are 20{degrees}-160{degrees} and 1.5-250 eV respectively.

  6. Fragmentation of multicharged C70q+ prepared in collisions with F+ ions at 3 keV

    Ionization and successive evaporation of C70r+ is studied as a function of the internal energy using collision induced dissociation under energy control. Multicharged ions C70r+ are prepared in F+ (3 keV) + C70 → F− + C70r+ + ne collisions. Up to seven successive evaporation of C2 are observed in an excitation energy range from 40 to 100eV. The dissociation energies of C70-2m2+ (m=1-7) are determined using a statistical cascade model to reproduce the excitation energy distribution of C702+ parent ions for each dissociation channel. Results are in good agreement with previous theoretical calculations

  7. Search for a 17 keV neutrino in the internal bremsstrahlung spectrum of 125I

    We have searched for evidence of the emission of a 17 keV neutrino in the internal bremsstrahlung (IB) spectrum accompanying the electron capture decay of 125I. The IB spectrum, recorded in a planar Ge detector, has 1.2x106 counts per keV at 17 keV below the 2p end point. We set an upper limit of 0.4% for the admixture of a 17 keV neutrino, at the 90% confidence level, and exclude a 0.8% admixture at the 99.6% confidence level. The QEC value is found to be 185.77±0.06 keV. We also find that the recent calculations of Suric et al., which employ relativistic self-consistent-field atomic wave functions, reproduce the shape and relative intensity of IB partial spectra within a few percent

  8. Electron double differential distribution in ionization of helium by 8 keV electron impact

    Electrons emitted from He in collision with 8 keV electrons were measured in the energy range from 1 to 400 eV and wide range of observation angles between 30 deg and 150 deg. The measured energy and angular distribution of double differential cross sections (DOCS) of these electrons are compared with the theoretical calculation provided by R.D. Rivarola et al. The single differential cross sections (SDCS) are deduced by integrating the DDCSs over solid angle and emission energy. For the calculation of DDCS for He a first-order Born approximation is employed. Within the framework of this model, both the incident and the scattered electrons are described by plane waves, whereas the initial atomic bound state is described by a Lowdin's wavefunction and the final continuum state for the ionized electron is chosen taken into account the interaction between the emitted electron and the residual target at large asymptotic separations. The experimental data is in reasonably good agreement with the theoretical predictions. (author)

  9. Comment on the paper "Dark matter searches going bananas: the contribution of Potassium (and Chlorine) to the 3.5 keV line" by T. Jeltema and S. Profumo

    Boyarsky, A; Iakubovskyi, D; Ruchayskiy, O

    2014-01-01

    We revisit the X-ray spectrum of the central 14' of the Andromeda galaxy, discussed in our previous work [1402.4119]. Recently in [1408.1699] it was claimed that if one limits the analysis of the data to the interval 3-4 keV, the significance of the detection of the line at 3.53 keV drops below 2 sigma. In this note we show that such a restriction is not justified, as the continuum is well-modeled as a power law up to 8 keV, and parameters of the background model are well constrained over this larger interval of energies. This allows for a detection of the line at 3.53 keV with a statistical significance greater than ~3 sigma and for the identification of several known atomic lines in the energy range 3-4 keV. Limiting the analysis to the 3-4 keV interval results in increased uncertainty, thus decreasing the significance of the detection. We also argue that, with the M31 data included, a consistent interpretation of the 3.53 keV line as an atomic line of K XVIII in all studied objects is problematic.

  10. Electron back-scattering coefficient below 5 keV: Analytical expressions and surface-barrier effects

    Cazaux, J.

    2012-10-01

    Simple analytical expressions for the electron backscattering coefficient, η, are established from published data obtained in the ˜0.4-5 keV range for 21 elements ranging from Be to Au. They take into account the decline in η with a decrease in energy E° for high-Z elements and the reverse behavior for low-Z elements. The proposed expressions for η (E°) lead to crossing energies situated in the 0.4-1 keV range and they may be reasonably extended to any of the other elements—via an interpolation procedure—to metallic alloys and probably to compounds. The influence of the surface barrier on the escape probability of the back-scattered electrons is next evaluated. This evaluation provides a theoretical basis to explain the observed deviation between various published data as a consequence of surface contamination or oxidation. Various practical applications and strategies are deduced for the η-measurements in dedicated instruments as well for the image interpretation in low voltage scanning electron microscopy based on the backscattered electron detection. In this microscopy, the present investigation allows to generalize the scarce contrast changes and contrast reversals previously observed on multi elemental samples and it suggests the possibility of a new type of contrast: the work function contrast.

  11. Radiation in the wavelength range 120-900 nm from keV electron bombardment of solid hydrogens

    Schou, Jørgen; Stenum, B.; Sørensen, H.;

    1991-01-01

    The emission of light from hydrogenic pellet material has been studied in a special experimental set-up. The measurements show that the intensity of light from particle bombarded solid hydrogens is very small and that none of the well known lines for the gas phase are emitted from the solid. The ...

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

    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.

  13. Accurate transport simulation of electron tracks in the energy range 1 keV-4 MeV

    Cobut, V. E-mail: vincent.cobut@chim.u-cergy.fr; Cirioni, L.; Patau, J.P

    2004-01-01

    Multipurpose electron transport simulation codes are widely used in the fields of radiation protection and dosimetry. Broadly based on multiple scattering theories and continuous energy loss stopping powers with some mechanism taking straggling into account, they give reliable answers to many problems. However they may be unsuitable in some specific situations. In fact, many of them are not able to accurately describe particle transport through very thin slabs and/or in high atomic number materials, or also when knowledge of high-resolution depth dose distributions is required. To circumvent these deficiencies, we developed a Monte Carlo code simulating each interaction along electron tracks. Gas phase elastic cross sections are corrected to take into account solid state effects. Inelastic interactions are described within the framework of the Martinez et al. [J. Appl. Phys. 67 (1990) 2955] theory intended to deal with energy deposition in both condensed insulators and conductors. The model described in this paper is validated for some materials as aluminium and silicon, encountered in spectrometric and dosimetric devices. Comparisons with experimental, theoretical and other simulation results are made for angular distributions and energy spectra of transmitted electrons through slabs of different thicknesses and for depth energy distributions in semi-infinite media. These comparisons are quite satisfactory.

  14. Response of X-UV photodiodes to 1.5-17.5 keV x rays and MeV alpha particles

    Wenzel, Kevin W.; Li, Chi-Kang; Petrasso, Richard D.; Lo, Daniel H.; Bautz, Marshall W.; Ricker, George R., Jr.; Hsieh, Ed

    1993-07-01

    The absolute x-ray response of three X-UV photodiodes was measured over an energy range of 1.5-17.5 keV so that they could be used to calibrate x-ray imaging systems for the ASCA satellite mission. An intense electron-beam x-ray generator was used to test both the dc and ac x-ray response at 1.5, 4.5, 8.0, and 17.5 keV, and an 55Fe source was used to examine one of the photodiodes at 5.9 keV. The x-ray response was determined by comparing the X-UV diode signal to that of a previously calibrated silicon surface barrier diode (SBD). The X-UV detector response was similar to the SBD response at low energies (1.5 and 4.5 keV). At 8 keV, the X-UV detectors exhibited about 70% of the SBD response, and at 17.5 keV, about 50%. This result is surprising, because the X-UV diodes actually have a greater silicon thickness than the SBD. In contrast to our findings for SBDs in the past, this implies that not the entire physical volume of these detectors comprises the active volume. The X-UV detector x-ray response was also examined as a function of the applied bias voltage. No significant bias voltage dependence of the x-ray signal was found, which indicates that the depletion layer thickness does not determine the active volume either. However, the detector noise was found to decrease substantially as the applied bias was raised from zero to a few volts. Response of these detectors, operated in pulse mode, to 226Ra α particles indicated large charge carrier recombination in the bulk silicon. This feature renders these detectors unsuitable for most charged-particle spectroscopy applications.

  15. HEAO 1 Observations of the Perseus cluster above 10 keV

    We present the results of HEAO 1 observations of the Perseus cluster from 10 to 150 keV in 1977 August and 1978 February and August. The spectrum exhibits a previously unknown hard (>25 keV) component in addition to the previously known thermal bremsstrahlung emission. The data presented show no significant evidence of variability from 10.5 keV to 93.5 keV, and a comparison of our results with earlier results indicates no strong evidence for variability above 25 keV over a time scale of approx. 4 yr. If the hard-component excess is due to NGC 1275, the data imply a 2--6 keV X-ray luminosity of approx.1 x 1044 ergs s -1 for the galaxy, or approx.15% of the total cluster emission from 2 to 6 keV and a 25--40 luminosity of approx.8 x 1043 ergs s-1. In the context of a model of hard-X-ray emission by inverse Compton scattering of relativistic electrons on the 2.7 K background, the X-ray spectrum, in conjuction with previously reported radio data, implies a magnetic field of B>10-7 gauss

  16. 723 keV beta transition in the negatron decay of 122Sb

    The energy dependence of the angular correlation of the cascade 2-(723 keV β particle) 2+(1260 keV γ ray)0+ in the decay of 122Sb is measured and found to agree with the reports of Raghavan et al. and Yamada et al. Nuclear matrix elements governing the 723 keV β transition are extracted using the available experimental data on this transition. Buhring's formulas that are simplified by Simms are used in the analysis. It is observed that the contribution of the nondiagonal elements to the Coulomb Hamiltonian is significant

  17. Resonance parameters for measured keV neutron capture cross sections

    All available neutron capture cross sections in the keV region (∼ to 100 keV) have been fitted with resonance parameters. Capture cross sections for nuclides with reasonably well known average s-wave parameters, but no measured cross section, have been calculated and tabulated using p-and d- wave strength functions interpolated between fitted values. Several of these nuclides are of interest in the theory of slow nucleosynthesis of heavy elements in stars, and the product of cosmic abundance (due to the s-process) and capture cross section at 30 keV has been plotted versus mass number. (author)

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

    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.

  19. Neutron cross sections of 122Te, 123Te, and 124Te between 1 and 60 keV

    The currently favored s process scenario of helium shell burning in low mass stars involves a range of thermal energies from kT=12 to 25 keV with most of the neutron exposure taking place at low temperatures. Therefore, differential cross sections are required down to the region of resolved resonances for the reliable determination of the Maxwellian-averaged cross sections typical of the stellar plasma. This work deals with the neutron capture cross sections of the important s only isotopes 122Te, 123Te, and 124Te, which were measured between 1 and 60 keV neutron energy with a setup of Moxon-Rae detectors. The systematic uncertainties achieved in this experiment are ∼5%, but statistical uncertainties are smaller than 2%. In addition to the Moxon-Rae detectors, the setup includes a 6Li glass detector which could be used to determine the total neutron cross sections simultaneously. These results represent the first set of experimental data in this energy range

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

    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

  1. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    The fabrication and performance of multilayer Al2O3/Ta2O5 Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported. Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al2O3/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV

  2. Theoretical evidence of 50 keV fermionic dark matter from galactic observables

    Argüelles, C R; Ruffini, R

    2016-01-01

    We have recently introduced a new model for the distribution of dark matter (DM) in galaxies, the Ruffini-Arg\\"uelles-Rueda (RAR) model, based on a self-gravitating system of massive fermions at finite temperatures. The RAR model, for fermion masses above keV, successfully describes the DM halos in galaxies, and predicts the existence of a denser quantum core towards the center of each configuration. We demonstrate here, for the first time, that the introduction of a cutoff in the fermion phase-space distribution, necessary to account for the finite Galaxy size, defines a new solution with a compact quantum core which represents an alternative to the central black hole (BH) scenario for SgrA*. For a fermion mass in the range $48$~keV$/c^2\\lesssim m \\lesssim 345$~keV$/c^2$, the DM halo distribution fulfills the most recent data of the Milky Way rotation curves, while harbors a dense quantum core of $4\\times10^6 M_\\odot$ within the S2 star pericenter. In particular, for a fermion mass of $m\\sim 50$~keV$/c^2$ th...

  3. The BeppoSAX 2-10 keV Survey

    Giommi, P; Fiore, F

    2000-01-01

    We present the results of a 2-10 keV BeppoSAX survey based on 140 high galactic latitude MECS fields, 12 of which are deep exposures of ``blank'' parts of the sky. The limiting sensitivity is 5 10^-14 erg cm^-2 s^-1 where about 25% of the Cosmic X-ray Background (CXB) is resolved into discrete sources. The logN-logS function, built with a statistically complete sample of 177 sources, is steep and in good agreement with the counts derived from ASCA surveys. A CXB fluctuation analysis allowed us to probe the logN-logS down to about 1.5 10^-14 erg cm^-2 s^-1 where the contribution of discrete sources to the CXB grows to 40-50%. A hardness ratio analysis reveals the presence of a wide range of spectral shapes and that a fairly large fraction of sources appear to be heavily absorbed, some of which showing soft components. A comparison of the flux distribution of different subsamples confirms the existence of a spectral hardening with decreasing flux. This effect is probably due to an increasing percentage of absor...

  4. Experimental charge fractions of hydrogen scattered from insulators at 50-340 keV

    Ross, Graham G

    2002-01-01

    Ion bombardment of insulators induces accumulation of electric charges at and under the insulator surfaces. This paper deals with the effect of the accumulated electric charges on the charge fractions of scattered hydrogen. We have measured and compiled charge fractions of hydrogen, in the energy range (for the scattered particles) from 50 to 340 keV, scattered from polystyrene, polymethylmethacrylate, polycarbonate, polyethylene and silicon. In order to establish the effect of the charge accumulation, some samples have been cut from a thick (1 mm) sheet, while some others have been spin coated (approx 250 nm) onto silicon wafers. Experimental measurements have been fitted with the equation f(0)=Aexp(-V sup 2 /V sub i V sub 0), where f(0) is the neutral fraction, V the velocity, V sub i the 'Bohr velocity' for the electron of projectiles, A and V sub 0 the fitting parameters. Comparisons using the least-square fitting procedure have shown that the accumulation of electric charges on the thick polymer samples ...

  5. Ion-induced photon emission of magnesium aluminate spinel during 60 keV Cu - implantation

    Bandourko, V.; Lay, T. T.; Takeda, Y.; Lee, C. G.; Kishimoto, N.

    2001-04-01

    The beam-solid interaction during high flux heavy-ion implantation has been studied by the in situ detection of photon emission. A spinel of MgO· n(Al 2O 3) with n=2.4 was irradiated with 60 keV Cu - at dose rates of 10, 50 or 100 μA/cm 2 to a dose of 1.5×10 17 ions/cm2. Under the implantation, photon emission ranging from 1.4 to 6.2 eV was detected by a time-resolved optical device based on a fast-response CCD (Princeton Instruments: IMAX-512). Emission lines of sputtered Mg, Al and Cu atoms were observed. A comparison of the dose and dose rate dependence of the Cu I line intensity from MgO· n(Al 2O 3) with those obtained for amorphous (a-)SiO 2 substrate revealed the good correlation of Cu I line intensity with nanoparticle formation detected by optical absorbance measurement.

  6. Ion-induced photon emission of magnesium aluminate spinel during 60 keV Cu- implantation

    The beam-solid interaction during high flux heavy-ion implantation has been studied by the in situ detection of photon emission. A spinel of MgO·n(Al2O3) with n=2.4 was irradiated with 60 keV Cu- at dose rates of 10, 50 or 100 μA/cm2 to a dose of 1.5x1017 ions/cm2. Under the implantation, photon emission ranging from 1.4 to 6.2 eV was detected by a time-resolved optical device based on a fast-response CCD (Princeton Instruments: IMAX-512). Emission lines of sputtered Mg, Al and Cu atoms were observed. A comparison of the dose and dose rate dependence of the Cu I line intensity from MgO·n(Al2O3) with those obtained for amorphous (a-)SiO2 substrate revealed the good correlation of Cu I line intensity with nanoparticle formation detected by optical absorbance measurement

  7. Experimental charge fractions of hydrogen scattered from insulators at 50-340 keV

    Ion bombardment of insulators induces accumulation of electric charges at and under the insulator surfaces. This paper deals with the effect of the accumulated electric charges on the charge fractions of scattered hydrogen. We have measured and compiled charge fractions of hydrogen, in the energy range (for the scattered particles) from 50 to 340 keV, scattered from polystyrene, polymethylmethacrylate, polycarbonate, polyethylene and silicon. In order to establish the effect of the charge accumulation, some samples have been cut from a thick (1 mm) sheet, while some others have been spin coated (∼250 nm) onto silicon wafers. Experimental measurements have been fitted with the equation f(0)=Aexp(-V2/ViV0), where f(0) is the neutral fraction, V the velocity, Vi the 'Bohr velocity' for the electron of projectiles, A and V0 the fitting parameters. Comparisons using the least-square fitting procedure have shown that the accumulation of electric charges on the thick polymer samples have decreased the values of the fitting parameter A which is more sensitive to the fractions at lower energies. On the other hand, an increase of the pressure in the vacuum chamber during the ion scattering has induced a general increase on the fitting parameter V0 which impairs the global trend of the fractions with energy or velocity

  8. MULTI-KEV X-Ray Yields From High-Z Gas Targets Fielded At Omega

    The authors report on modeling of x-ray yield from gas-filled targets shot at the OMEGA laser facility. The OMEGA targets were 1.8 mm long, 1.95 mm in diameter Be cans filled with either a 50:50 Ar:Xe mixture, pure Ar, pure Kr or pure Xe at ∼ 1 atm. The OMEGA experiments heated the gas with 20 kJ of 3ω (∼ 350 nm) laser energy delivered in a 1 ns square pulse. the emitted x-ray flux was monitored with the x-ray diode based DANTE instruments in the sub-keV range. Two-dimensional x-ray images (for energies 3-5 keV) of the targets were recorded with gated x-ray detectors. The x-ray spectra were recorded with the HENWAY crystal spectrometer at OMEGA. Predictions are 2D r-z cylindrical with DCA NLTE atomic physics. Models generally: (1) underpredict the Xe L-shell yields; (2) overpredict the Ar K-shell yields; (3) correctly predict the Xe thermal yields; and (4) greatly underpredict the Ar thermal yields. However, there are spreads within the data, e.g. the DMX Ar K-shell yields are correctly predicted. The predicted thermal yields show strong angular dependence.

  9. Contribution to proton transport simulation from the MeV range to the keV range by the Monte-Carlo method

    This study settles on a contribution to the elaboration of slow protons transport simulation. Atomic inner shell ionization is studied in the Plane Wave Born Approximations and in the Binary Encounter Approximation. BRINKMAN-KRAMER's theory and DMITRIEV's theory are used to study charge exchange phenomena. Protons slowing down is studied with the BRICE's stopping power, with the VAVILOV and SYMON's energy straggling distributions and with the MOLIERE, KEIL and MEYER's angular deflexion distributions. Transport simulation is made with Monte Carlo Method; K electrons motion is also taken into account

  10. The BeppoSAX 2-10 keV survey

    Giommi, P.; Perri, M.; Fiore, F.

    2000-10-01

    We present the results of a 2-10 keV BeppoSAX survey based on 140 high galactic latitude MECS fields, 12 of which are deep exposures of ``blank'' parts of the sky. The limiting sensitivity is 5*E-14 erg cm -2s-1 where about 25% of the Cosmic X-ray Background (CXB) is resolved into discrete sources. The logN-logS function, built with a statistically complete sample of 177 sources, is steep and in good agreement with the counts derived from ASCA surveys. A CXB fluctuation analysis allowed us to probe the logN-logS down to about 1.5*E-14 erg cm -2s-1 where the contribution of discrete sources to the CXB grows to ~ 40-50%. A hardness ratio analysis reveals the presence of a wide range of spectral shapes and that a fairly large fraction of sources appear to be heavily absorbed, some of which showing soft components. A comparison of the flux distribution of different subsamples confirms the existence of a spectral hardening with decreasing flux. This effect is probably due to an increasing percentage of absorbed sources at faint fluxes, rather than to a gradual flattening of the spectral slope. Nearly all the sources for which adequate ROSAT exposures exist, have been detected in the soft X-rays. This confirms that soft spectral components are present even in strongly absorbed objects, and that a large population of sources undetectable below a few keV does not exist. A Ve/Va test provides evidence for the presence of cosmological evolution of a magnitude similar to that found in soft X-ray extragalactic sources. Evolution is present both in normal and absorbed sources, with the latter population possibly evolving faster, although this effect could also be the result of complex selection effects. Table 1 is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html

  11. TL response of single crystal TLD-100 to 70 eV: 5 keV electrons and comparison with TSEE glow curves

    Lasky, J.B.; Moran, P.R.

    1976-01-01

    A ''TL effective'' energy-range relationship was found which agrees with the universal curve above 2 keV but becomes nearly constant at about 300/sup 0/A for energies between 1 keV and 100 eV. The glow curve shape obtained from single crystal TLD-100, after irradiation with 70 eV to 30 keV electrons, is essentially the same as that obtained after irradiation with cesium ..gamma..-rays, (i.e. TL emitted from bulk of sample) as long as (1) the dose is well below saturation and (2) irradiations are performed on freshly cleaved crystals or vacuum annealed crystals. This result shows that there is no intrinsic difference between TL traps near the surface and in the bulk. Irradiation with electron energies less than 1 keV results in the TL signal being emitted from the same region from which TSEE electrons are emitted. The usual TSEE glow curve, found by other investigators, is different from the TL glow curve obtained from vacuum annealed crystals. However, if the TL sample is given the same ''standard annealing'' as is customary in TSEE experiments, the TL glow curve obtained after irradiation with low energy electrons is altered and there is then good agreement between this TL glow curve and the TSEE curve found by others. This altered glow curve is a result of hydroxyl ions which diffuse into the sample during annealing. The TL efficiency was comparable to cesium ..gamma..-rays for 30-5 keV electrons, decreased rapidly between 5 and 1 keV and remained constant at about 20% of the efficiency of cesium ..gamma..-rays below 1 keV. Half of this decrease in efficiency can be attributed to the higher LET of low energy electrons. The cause for the remaining decrease is not known but it may have its origin in the same mechanism proposed to account for the large range of low energy electrons.

  12. Neutron capture between 5 keV and 3 MeV

    Neutron capture cross-sections over a wide range of mass number are being measured for neutron energies between about 5 keV and 3 MeV. The nuclei studied to date are 41K, 85Rb, 86Sr, 87Rb, 89Y, 98Mo, 139La, 141Pr,158Gd, 170Er, 175Lu, and 176Yb. The experimental technique used is the activation method, in which the radioactive capture product formed in the neutron bombardment is measured by beta or gamma counting, and the counters are calibrated against a 4π-beta counter. Monoenergetic neutrons are produced by bombarding lithium or tritium targets with protons from the 4-MeV Van de Graaff accelerator. The neutron intensity is measured with a fission chamber, which counts fissions in a thin deposit of 235U. The data are compared with calculations based upon the statistical model of uncorrelated and non-interfering compound nuclear states. This model, which yields the energy averages of resonant or fluctuating compound nuclear cross-sections, was first used to calculate capture cross-sections by Lane and Lynn, and has been developed further by Moldauer. The calculations take into account the variation of radiation width and level density with excitation energy and spin of the compound nucleus, and include the competition of compound elastic and inelastic scattering and the variation of neutron widths from level to level (Porter-Thomas distribution). Neutron widths were calculated from optical model transmission coefficients, with the parameters chosen according to the spherical optical model of Moldauer. Another phenomenon is considered in the calculations. If the compound state, de-exciting through a gamma-ray cascade, ends its de-excitation in a low-lying level of (Z, A + 1), the event is radiative capture, as measured experimentally. If, however, after a gamma-ray decay, the compound system is at an excitation energy above the neutron emission threshold, the gamma-ray cascade may be ended by neutron emission, and the process does not contribute to the capture

  13. A possible link between the GeV excess and the 511 keV emission line in the Galactic Centre

    Boehm, Celine; Jean, Pierre; Lacroix, Thomas; Norman, Colin; Silk, Joseph

    2014-01-01

    Recently an excess of gamma rays in the GeV range has been reported by several groups. The signal appears to be confined within a 10 deg by 10 deg region located around the galactic centre (GC), with a morphology that is suggestive of a dark matter origin. Here we note that such characteristics (morphology and size of region) share striking similarities with the 511 keV emission line, first detected in the 1970s and eventually mapped by the INTEGRAL/SPI experiment in 2003. We show that if the origin of the excess is a 30 GeV dark matter candidate annihilating into b bar{b} or a 10 GeV particle annihilating into predominantly mu+ mu-, the subsequent number of low energy positrons in a 10 deg region around the GC can be large enough to explain the observed characteristics of the 511 keV emission. These findings thus suggest that the GeV excess and 511 keV emission line could actually share a common origin, therefore possibly enabling to elucidate the origin of the 511 keV line. We note also that any astrophysic...

  14. A Fresh Look at keV Sterile Neutrino Dark Matter from Frozen-In Scalars

    Adulpravitchai, Adisorn

    2014-01-01

    Sterile neutrinos with a mass of a few keV can serve as cosmological warm dark matter. We study the production of keV sterile neutrinos in the early universe from the decay of a frozen-in scalar. Previous studies focused on heavy frozen-in scalars with masses above the Higgs mass leading to a hot spectrum for sterile neutrinos with masses below 8-10 keV. Motivated by the recent hints for an X-ray line at 3.55 keV, we extend the analysis to lighter frozen-in scalars, which allow for a cooler spectrum. Below the electroweak phase transition, several qualitatively new channels start contributing. The most important ones are annihilation into electroweak vector bosons, particularly W-bosons as well as Higgs decay into pairs of frozen-in scalars when kinematically allowed.

  15. The g-factor of the 80.1 keV level in 144Pr

    The g-factor of the 80.1 keV level in 144Pr has been determined in an IPAC study of the 53.4-80.1 keV cascade. With an external magnetic field of 21.7(3)kG the precession angle ωtau was measured to be -0.045(12). The result g=-1.2(4) agrees well with that calculated in terms of coupling of the effective moments of the odd particles, g=-1.43(7). From the directional correlation of the 53.4-80.1 keV cascade the mixing ratio of the 53.4keV transition was determined, delta (E2/M1)=0.043(3). (Auth.)

  16. Study of the reactions 9Be(p, α)6Li, 9Be(p,d)8Be from 300 keV to 900 keV

    The experimental results concerning the two reactions 9Be(p,α)6Li and 9Be(p,d)8Be from 300 to 900 keV are presented. The angular distribution, excitation and total cross-section curves are expressed in absolute values after a normalization carried out using results given by Weber, Davis and Marion. (authors)

  17. Multipolarity of the 228.5-keV transition in 80Y

    We have unambiguously characterized the deexcitation of the 228.5-keV T1/2=4.7-s isomer in 80Y as an M3 transition. This result determines, in conjunction with other experimental data, the spin and parity of the 228.5-keV isomer and the 80Y ground state as 1- and 4-, respectively. (c) 2000 The American Physical Society

  18. Beam Spot Measurement on a 400 keV Electron Accelerator

    Miller, Arne

    A line probe is used to measure the beam spot radius and beam divergence at a 400 keV ICT electron accelerator, and a method is shown for reducing the line probe data in order to get the radial function.......A line probe is used to measure the beam spot radius and beam divergence at a 400 keV ICT electron accelerator, and a method is shown for reducing the line probe data in order to get the radial function....

  19. The Technique of Genetic Transformation Mediated by keV Ion Beam

    卞坡; 余增亮

    2005-01-01

    The application of keV ion beam in life science started in China several decades ago. In 1986, researchers initially studied the mutagenic effect of ion beam, and successfully applied it to plant breeding. Nowadays, ion beam implantation technique has been extensively applied to many biological fields. This paper mainly introduces one of its important applications: genetic transformation mediated by keV ion beam.

  20. First measurement of the antiproton-nucleus annihilation cross section at 125 keV

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

    2015-01-01

    The first observation of in-flight antiproton-nucleus annihilation at ∼130 keV obtained with the ASACUSA detector has demonstrated that the measurement of the cross section of the process is feasible at such extremely low energies Aghai-Khozani, H., et al., Eur. Phys. J. Plus 127, 55 (2012). Here we present the results of the data analysis with the evaluations of the antiproton annihilation cross sections on carbon, palladium and platinum targets at 125 keV.

  1. Angular and energy distributions of electrons from 7.5--150-keV proton collisions with oxygen and carbon dioxide

    Cross sections for the ejection of electrons, differential in the angle and energy of emission, were measured for proton collisions with two molecular gases, oxygen and carbon dioxide, over the primary energy range of 7.5--150 keV and an angular range of 10 degree to 160 degree. The energy distributions, obtained by integration over the angle, were fitted by an analytical model. A discrepancy in the angular distributions compared to those of Gibson and Reid [J. Phys. E 17, 1227 (1984); J. Phys. B 19, 3265 (1986); Radiat. Res. 112, 418 (1987); Australian Atomic Energy Commission Report No. AAEC/E659, 1987 (unpublished)] is discussed. At energies up to 50 or 100 keV, the angular distributions were found to be largely independent of the ejected electron energy and very similar for different targets

  2. Compact focusing spectrometer: Visible (1 eV) to hard x-rays (200 keV)

    Baronova, E. O.; Stepanenko, A. M.; Pereira, N. R.

    2014-11-01

    A low-cost spectrometer that covers a wide range of photon energies can be useful to teach spectroscopy, and for simple, rapid measurements of the photon spectrum produced by small plasma devices. The spectrometer here achieves its wide range, nominally from 1 eV to 200 keV, with a series of spherically and cylindrically bent gratings or crystals that all have the same shape and the same radius of curvature; they are complemented by matching apertures and diagnostics on the Rowland circle that serves as the circular part of the spectrometer's vacuum vessel. Spectral lines are easily identified with software that finds their positions from the dispersion of each diffractive element and the known energies of the lines.

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

    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.

  4. Injection and diffusive transport of suprathermal through energetic solar flare protons (35 keV to 20 MeV)

    Beeck, J.; Mason, G. M.; Hamilton, D. C.; Marsden, R. G.; Sanderson, T. R.

    1990-01-01

    Consideration is given to the injection and interplanetary propagation of low-energy protons caused by the solar particle event of July 20, 1981, in which flare protons in the range from 35 keV to 20 MeV were observed by instruments on ISEE 3. The observed time-intensity and time-anisotropy profiles were fitted over the entire energy range using a model based on the spherically symmetric Fokker-Plank equation, including convection, diffusion, and adiabatic deceleration. The results are used to discuss the behavior of the radial interplanetary diffusion coefficient and the scattering mean free path for protons. Also, evidence is found for diffusive coronal shock acceleration of protons during the event.

  5. Spectral albedo of photons of initial energies below 100 keV

    This paper shows the results of Monte Carlo simulations of the photon reflection from homogenous plates of the shield materials made of water, aluminum, and iron. Perpendicular incidence of a monoenergetic photon beam of the initial energy of 20 keV up to 100 keV is considered. The numerical experiments were performed using the verified Monte Carlo programs MCNP-4C, FOTELP-2K3, and PENELOPE-2005. As the result, the values of difference number albedo distributed in ten even intervals according to the energy and nine even intervals according to the polar angle of reflected photons were obtained. Out of these data, the spectral albedo coefficients for all three materials and three initial photon energies of 40 keV, 60 keV, and 100 keV were calculated, graphically presented, and analyzed. The values of the spectral albedo determined on the basis of MCNP-4C code were compared to the results of the early simulations of the photon reflection performed in Russia and in the USA. Also, with the help of MCNP-4C program, the yield of fluorescent photons to the spectrum of the reflected radiation was registered, which can be seen in the graphs in the form of the peak at the energy of 7.112 keV only at the shielding plates made of iron. (author)

  6. Search for 17-keV neutrinos in the internal bremsstrahlung spectrum of 125I

    We have conducted an experiment to search for the signature of a 17-keV neutrino in the internal bremsstrahlung (IB) spectrum of 125I. Gamma rays from a ∼ 100 mCi 125I point source were counted in a planar HPGe detector which is 16 mm in diameter and 10 mm in depth and which has a resolution of 560 eV at 122 keV. The source was counted for 61 d and the background for 17 d. At the start of the counting period the count rate was 650 s-1; the number of counts 17 keV below the 2p endpoint is 106 per keV. Data in the energy interval 120-150.5 keV were fitted with a theoretical spectrum calculated using nonrelativistic Hartree-Fock atomic wavefunctions. The preliminary fits reject the hypothesis of a 0.8% 17-keV neutrino at a confidence level of ≥ 98%. We are in the process of reanalyzing the data using recent relativistic theoretical shapes

  7. Measurement of energy distributions of secondary electrons ejected from argon by fast electrons. [Differential cross sections, 11 to 10 keV

    Vroom, D.A.; Palmer, R.L.; McGowan, J.W.

    1977-01-15

    Energy distributions of secondary electrons emitted in the ionization of argon by fast electrons have been measured. Their spectra and single and double differential cross sections were obtained for electron impact energies ranging from 1 to 10 keV, and electrons ejected with energies up to 300 eV. Where possible, the results are compared with existing experimental data and with theoretical calculations. (AIP)

  8. Structural investigation of keV Ar-ion-induced surface ripples in Si by cross-sectional transmission electron microscopy

    Chini, T. K.; Okuyama, F.; Tanemura, Masaki; Nordlund, K.; タネムラ, マサキ; 種村, 眞幸

    2003-01-01

    Using cross-section transmission electron microscopy (XTEM) we have studied the surface and subsurface structure of individual ripples having submicron scale wavelength and nanometer scale amplitude, generated by obliquely incident (50?120 keV) Ar ion bombardment of Si. The XTEM results reveal that the front slopes of ion-induced ripples have amorphous layers containing bubbles with sizes ranging from about 3 to 15 nm facing the ion beam direction. A hinner amorphous layer without bubbles, on...

  9. Effect of 200 keV Ar{sup +} implantation on optical and electrical properties of polyethyleneterepthalate (PET)

    Kumar, Rajiv, E-mail: rajiv.physics@gmail.com; Goyal, Meetika, E-mail: meetika89@gmail.com; Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu [Department of Physics, Kurukshetra University, Kurukshetra - 136119 (India); Kanjilal, D. [Inter University Accelerator Centre, New Delhi-110067 (India)

    2015-05-15

    In the present paper we have discussed the effect of 200 keV Ar{sup +} ions on the electrical and optical properties of PET samples. PET samples were implanted with 200 keV Ar{sup +} ions to various doses ranging from 1×10{sup 15} to 1×10{sup 17} Ar{sup +} cm{sup 2}. The changes in the electrical and optical properties of pristine and implanted PET specimens have been studied by using Keithley electrometer and UV-Visible absorption spectroscopy. The electrical conductivity has found to be increased with increasing ion dose. The optical studies have revealed the drastic alterations in optical band gap from 3.63 eV to 1.48 eV and also increase in number of carbon atoms per cluster from 215 to 537. Further, the change in the electrical conductivity and optical band gap has also been correlated with the formation of conductive islands in the implanted layers of PET.

  10. Measurement of the ionization yield of nuclear recoils in liquid argon at 80 and 233 keV

    Bondar, A; Dolgov, A; Grishnyaev, E; Polosatkin, S; Shekhtman, L; Shemyakina, E; Sokolov, A

    2014-01-01

    The energy calibration of nuclear recoil detectors is of primary importance to rare-event experiments such as those of direct dark matter search and coherent neutrino-nucleus scattering. In particular, such a calibration is performed by measuring the ionization yield of nuclear recoils in liquid Ar and Xe detection media, using neutron elastic scattering off nuclei. In the present work, the ionization yield for nuclear recoils in liquid Ar has for the first time been measured in the higher energy range, at 80 and 233 keV, using a two-phase Cryogenic Avalanche Detector (CRAD) and DD neutron generator. The ionization yield in liquid Ar at an electric field of 2.3 kV/cm amounted to 7.8+/-1.1 and 9.7+/-1.3 e-/keV at 80 and 233 keV respectively. Neither Jaffe model for nuclear recoil-induced ionization nor that of Thomas-Imel can consistently describe the energy dependence of the ionization yield.

  11. Effect of 750 keV Argon ion irradiation on nc ZnO−SiOx thin films

    Nanocomposite (nc) ZnO−SiOx thin films were grown using rf magnetron sputter deposition technique and post-deposition annealing at 750 °C. These films were irradiated with 750 keV Argon ions at fluences in the range from 1 × 1015 to 1 × 1017 ions/cm2, using Low Energy Ion Beam Facility (LEIBF) at IUAC. X-ray diffraction (XRD) patterns of the as-deposited irradiated films show decrease in intensity of ZnO peaks relative to pristine film. Fourier transform infrared (FT-IR) spectroscopy measurements of the as-deposited irradiated films indicate the breakage of Zn−O, Zn−O−Si and Si−O−Si bonds in them, which is substantiated by FT-IR measurements of 750 °C annealed films that were irradiated at a fluence of 1016 ions/cm2. Photoluminescence (PL) measurements show drastic decrease of visible PL emission from as-deposited irradiated films. Current−Voltage (I–V) measurements show decrease in surface resistance of irradiated films by three orders of magnitude. The results suggest that 750 keV argon ion irradiation of nc ZnO−SiOx films has resulted in the formation of non-radiative defects in ZnO phase and damage in SiOx, and amorphization in Zinc silicate phase. These results are explained on the basis of the dominant energy loss mechanism of low energy ions in materials

  12. Attosecond keV x-ray pulses driven by Thomson scattering in a tight focus regime

    The radiation of a relativistic electron interacting with a co-propagating tightly focused high-power laser is investigated. High-order fields (HOFs) existing in a tight focus (a few micrometers or so) affect the dynamics of electrons rather significantly so as to enhance radiation intensity by several orders of magnitude. In the case of a co-propagating interaction geometry, the second-order field plays an important role in radiation enhancement. It is demonstrated that when HOFs are included, the radiation efficiency is increased by a factor of up to 100 000 for w0 = 2 and 5 μm, with a laser intensity of 2.2x1020 W cm-2, compared with that when HOFs are not included. The enhancement is larger for smaller electron energies and laser beam waists. It has also been shown that when an electron bunch interacts with a high-intensity tightly-focused femtosecond laser pulse in a co-propagation geometry, attosecond (∼300 as) x-ray pulses can be produced. The photon energy can reach about 40 keV for an electron energy of 2 GeV. The physical scheme investigated in this work can be used for an ultrafast (attosecond or femtosecond) x-ray source in the range of 10-100 keV.

  13. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling.

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne; Szeghalmi, Adriana; Knez, Mato; Weigand, Markus; Snigirev, Anatoly; Snigireva, Irina; Schütz, Gisela

    2013-05-01

    Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ~10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al2O3/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV. PMID:23592622

  14. Correlation between blister skin thickness, the maximum in the damage-energy distribution, and projected ranges of He+ ions in metals: V

    In these experiments a systematic study of the correlation of the skin thickness measured directly by scanning electron microscopy with both the calculated projected-range values and the maximum in the damage-energy distribution has been conducted for a broad helium-ion energy range (100 keV-1000 keV in polycrystalline vanadium. (Auth.)

  15. 3.5 keV X-ray line and R-Parity Conserving Supersymmetry

    Dutta, Bhaskar; Khalid, Rizwan; Shafi, Qaisar

    2014-01-01

    We present some R-parity conserving supersymmetric models which can accommodate the 3.5 keV X-ray line reported in recent spectral studies of the Perseus galaxy cluster and the Andromeda galaxy. Within the Minimal Supersymmetric Standard Model (MSSM) framework, the dark matter (DM) gravitino (or the axino) with mass of around 7 keV decays into a massless neutralino (bino) and a photon with lifetime ~10^{28} sec. The massless bino contributes to the effective number of neutrino species N_eff and future data will test this prediction. In the context of NMSSM, we first consider scenarios where the bino is massless and the singlino mass is around 7 keV. We also consider quasi-degenerate bino-singlino scenarios where the mass scale of DM particles are O(GeV) or larger. In such a scenario we require the mass gap to generate the 3.5 keV line. We comment on the possibility of a 7 keV singlino decaying via R parity violating couplings while all other neutralinos are heavy.

  16. Origin of the 871-keV gamma ray and the ''oxide'' attribute

    This work concludes the investigation of the oxide attribute of current interest for the characterization of stored plutonium. Originally it was believed that the presence of oxide could be ascertained by measurement of the 871-keV line in a high-resolution gamma-ray spectrum. However, recent work has suggested that the 871-keV gamma ray in plutonium oxide arises from the reaction 14N(α,p)17O rather than the inelastic scattering reaction 17O(α,αprime)17O*. This conclusion, though initially surprising, was obtained during efforts to determine the relative importance of americium and plutonium alpha-particle decay for the production of the 871-keV gamma ray. Several questions were raised by previous experiments: What role, if any does 17O have in the generation of the 871-keV gamma ray? How does sufficient nitrogen come to be present in plutonium oxide? Under what conditions is the 871-keV gamma ray measurable in plutonium oxide? This paper describes the answers to these questions

  17. Influence of ~7 keV sterile neutrino dark matter on the process of reionization

    Rudakovskyi, Anton; Iakubovskyi, Dmytro

    2016-06-01

    Recent reports of a weak unidentified emission line at ~3.5 keV found in spectra of several matter-dominated objects may give a clue to resolve the long-standing problem of dark matter. One of the best physically motivated particle candidate able to produce such an extra line is sterile neutrino with the mass of ~7 keV . Previous works show that sterile neutrino dark matter with parameters consistent with the new line measurement modestly affects structure formation compared to conventional cold dark matter scenario. In this work, we concentrate for the first time on contribution of the sterile neutrino dark matter able to produce the observed line at ~3.5 keV, to the process of reionization. By incorporating dark matter power spectra for ~7 keV sterile neutrinos into extended semi-analytical `bubble' model of reionization we obtain that such sterile neutrino dark matter would produce significantly sharper reionization compared to widely used cold dark matter models, impossible to `imitate' within the cold dark matter scenario under any reasonable choice of our model parameters, and would have a clear tendency of lowering both the redshift of reionization and the electron scattering optical depth (although the difference is still below the existing model uncertainties). Further dedicated studies of reionization (such as 21 cm measurements or studies of kinetic Sunyaev-Zeldovich effect) will thus be essential for reconstruction of particle candidate responsible the ~3.5 keV line.

  18. CdZnTe x-ray detector for 30 {endash} 100 keV energy

    Yoo, S.-S. [Illinois Univ., Chicago, IL (United States). Dept. of Physics][Argonne National Lab., IL (United States); Rodricks, B.; Shastri, S.D. [Argonne National Lab., IL (United States); Montano, P.A. [Illinois Univ., Chicago, IL (United States). Dept. of Physics][Argonne National Lab., IL (United States)

    1996-07-01

    High-pressure-Bridgman (HPB) grown CdZnTe x-ray detectors 1.25-1.7 mm thick were tested using monochromatic x-rays of 30 to 100 keV generated by a high energy x-ray generator. The results were compared with a commercially available 5 cm thick NaI detector. A linear dependence of the counting rate versus the x-ray generator tube current was observed at 58.9 keV. The measured pulse height of the photopeaks shows a linear dependence on energy. Electron and hole mobility-lifetime products ({mu}{tau}) were deduced by fitting bias dependent photopeak channel numbers at 30 keV x-ray energy. Values of 2 x 10{sup -3} cm{sup 2}/V and 2 x 10{sup -4}cm{sup 2}/V were obtained for {mu}{tau}{sub e} and {mu}{tau}{sub p}, respectively. The detector efficiency of CdZnTe at a 100 V bias was as high as, or higher than 90 % compared to a NaI detector. At x-ray energies higher than 70 keV, the detection efficiency becomes a dominant factor and decreases to 75 % at 100 keV.

  19. Contribution of backscattered electrons to the total electron yield produced in collisions of 8–28 keV electrons with tungsten

    R K Yadav; R Shanker

    2007-03-01

    It is shown experimentally that under energetic electron bombardment the backscattered electrons from solid targets contribute significantly (∼ 80%) to the observed total electron yield, even for targets of high backscattering coefficients. It is further found that for tungsten ( = 74) with a backscattering coefficient of about 0.50, about 20% of the total electron yield is contributed by the total secondary electrons for impact energies in the range of 8–28 keV. The yield of true backscattered electrons at normal incidence (0), total secondary electrons () and the total electron yield (tot) produced in collisions of 8–28 keV electrons with W have been measured and compared with predictions of available theories. The present results indicate that the constant-loss of primary electrons in the target plays a significant role in producing the secondary electrons and that it yields a better fit to the experiment compared to the power-law.

  20. Sputtering of tungsten: an atomic view of a near-surface depleted zone created by a single 30 keV 63Cu+ projectile. Report No. 4118

    The vacancy structure of a near-surface depleted zone (DZ), created by a single 30 keV 63Cu+ ion in a tungsten field-ion microscope (FIM) specimen, was determined with atomic resolution. Both the irradiation and pulse field-evaporation experiments were performed in situ at less than or equal to 11 K, so that the observed vacancy structure was unaltered by the long-range migration of self-interstitial atoms. The following basic physical quantities were measured: (1) the number of vacancies; (2) the dimensions; (3) the vacancy concentration; (4) the distribution of first-nearest-neighbor vacancy clusters; and (5) the radial-distribution function for the vacancies out to ninth-nearest neighbor. The values of these quantities were shown to be similar for both the near-surface DZ and DZs created in the bulk of the same specimen by 30 keV 63Cu+ projectiles

  1. Determination of the molecular structure via the medium energy electrons (500 eV-1,5 KeV) Ar, N2, Co e HCl

    Elastic Differential and Total Differential Cross Sections are measured for electron collision in medium-energy range (500 eV - 1,5 KeV) with argon, nitrogen, carbon monoxide and hydrogen chloride, all in their electronic ground state. Theoretical calculation for the Elastic Differential Cross Sections by atoms were done employing Hartree-Fock-Clementy wave function, and making use of Partial Wave and WKBJ Methods. Exchange effect is included in the case of argon. Independent Atom Model, Half Molecule Model and a new model, the Ionic Model were utilized for the molecular calculations. The Ionic Model is suggested for the interaction between HCl and electrons. Inelastic Differential Cross Section were also computed, making use of the First Born Approximation and Hartree-Fock-Clementi wave function. It is also demonstrated, for the first time, that medium energy electrons (500 eV - 1,5 Kev) can be used to determine molecular structure parameters, in gas phase

  2. Superconducting transition-edge-microcalorimeter X-ray spectrometer with 2 eV energy resolution at 1.5 keV

    We describe the operation and performance of a prototype microcalorimeter 'energy-dispersive' (non-dispersive) X-ray spectrometer (μcal EDS) developed at NIST for use in X-ray microanalysis and X-ray astronomy. The low-energy microcalorimeter detector, consisting of an Al-Ag bilayer superconducting transition-edge sensor (TES) in thermal contact with a Bi X-ray absorber, is designed for operation in the energy range from 0-2 keV and is fabricated using a shadow-mask lithographic process. The TES microcalorimeter is cooled by a compact adiabatic demagnetization refrigerator and is mounted on a scanning electron microscope. This device achieves a best energy resolution of 2.0±0.1 eV at 1.5 keV, as determined from the analysis of digitized X-ray spectra of a complex glass containing many elements

  3. Some characteristics of X-ray imaging for energy region of over 100 keV using plastic scintillation fiber array

    TANG Shibiao; MA Qingli; YIN Zejie; HUANG Huan

    2007-01-01

    In this work, characteristics of using PSFs (plastic scintillation fibers) coupled with CCD (charge-coupled devices ) to build area detectors for high energy X-ray imaging are studied with a Monte Carlo simulation, which cover an energy range of a few hundred kev to about 20 MeV. It was found that the efficiency of PSF in detecting X-ray with energy above a few hundred kev is low. We can use large incident flux to increase the output signal to noise ratio (SNR). The performance can also be improved by coating PSF with X-ray absorption layers and the MTF of the system is presented. By optimizing the absorption layer thickness, the crosstalk of the area detector built with PSF decreases.

  4. One-sided imaging of large, dense objects using the 511 keV photons from induced pair production

    Tavora, L.M.; Gilboy, W.B.; Morton, E.J. [Univ. of Surrey, Guildford (United Kingdom). Physics Dept.; Morgado, R.E.; Estep, R.J.; Rawool-Sullivan, M. [Los Alamos National Lab., NM (United States)

    1998-03-01

    The use of annihilation photons from photon-induced electron-positron pair production as a means of inspecting objects when only one side is accessible is described. The Z2 dependence of the pair production cross section and the high penetration of 511 keV photons suggest that this method should be capable of localizing high Z materials in lower Z matrices. The experimental results for the dependence of the back streaming photon yield on Z indicate that dynamic ranges of the order of 20 may be obtained for materials with 4 < Z < 82. Results for point to point images obtained in line scans of representative geometries are also shown. Simulation studies based on the EGS4 Monte Carlo code were also performed and their results show an agreement with experimental data of the order of 5%.

  5. Sputtering and surface state evolution of Bi under oblique incidence of 120 keV Ar{sup +} ions

    Mammeri, S. [CRNA, B.P. 399, 02 Bd. Frantz Fanon, Alger-Gare, Algiers (Algeria); Ouichaoui, S., E-mail: souichaoui@usthb.d [Universite des Sciences et de la Technologie Houari Boumediene (USTHB), Faculte de Physique, Laboratoire SNIRM, B.P. 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria); Ammi, H.; Hammoudi, H. [CRNA, B.P. 399, 02 Bd. Frantz Fanon, Alger-Gare, Algiers (Algeria); Pineda-Vargas, C.A. [iThemba Labs, MRG, P.O. Box 722, Somerset West, Cape Town 7129 (South Africa)

    2011-05-01

    The sputtering and surface state evolution of Bi/Si targets under oblique incidence of 120 keV Ar{sup +} ions have been investigated over the range of incidence angles 0{sup o} {<=} {theta}{sub i} {<=} 60{sup o}. Increasing erosion of irradiated samples (whose surface thickness reduced by {approx}3% at normal incidence up to {approx}8% at {theta} = 60{sup o}) and their surface smoothing with reducing grain sizing were pointed out using Rutherford backscattering (RBS), atomic force (AFM) and X-ray diffraction (XRD) techniques. Measured sputtering yield data versus {theta}{sub i} with fixed ion fluence to {approx}1.5 x 10{sup 15} cm{sup -2} are well described by Yamamura et al. semi-empirical formula and Monte Carlo (MC) simulation using the SRIM-2008 computer code. The observed increase in sputter yield versus incidence angle is closely correlated to Bi surface topography and crystalline structure changes under ion irradiation.

  6. One-sided imaging of large, dense objects using the 511 keV photons from induced pair production

    The use of annihilation photons from photon-induced electron-positron pair production as a means of inspecting objects when only one side is accessible is described. The Z2 dependence of the pair production cross section and the high penetration of 511 keV photons suggest that this method should be capable of localizing high Z materials in lower Z matrices. The experimental results for the dependence of the back streaming photon yield on Z indicate that dynamic ranges of the order of 20 may be obtained for materials with 4 < Z < 82. Results for point to point images obtained in line scans of representative geometries are also shown. Simulation studies based on the EGS4 Monte Carlo code were also performed and their results show an agreement with experimental data of the order of 5%

  7. Surface damage in TEM thick α-Fe samples by implantation with 150 keV Fe ions

    We have performed molecular dynamics simulations of implantation of 150 keV Fe ions in pure bcc Fe. The thickness of the simulation box is of the same order of those used in in situ TEM analysis of irradiated materials. We assess the effect of the implantation angle and the presence of front and back surfaces. The number and type of defects, ion range, cluster distribution and primary damage morphology are studied. Results indicate that, for the very thin samples used in in situ TEM irradiation experiments the presence of surfaces affect dramatically the damage produced. At this particular energy, the ion has sufficient energy to damage both the top and the back surfaces and still leave the sample through the bottom. This provides new insights on the study of radiation damage using TEM in situ

  8. Phenomenological treatments of cross sections for proton and hydrogen impact below 1 keV on molecular nitrogen

    An analytic independent-particle model is used to construct static potentials to describe the interaction of hydrogenlike ions with atoms and molecules. Parameters of the ion--atom potential are determined from ab initio total energy minimization procedure. The elastic scattering of He+ from Ne and Ar is investigated as a test case and comparison is made with experiment. The model is then used in conjunction with low energy H+--N2 experimental data to construct differential and total cross sections for the scattering of protons and hydrogen in the energy range 10 eV to 1 keV from molecular nitrogen. Analytic forms are used to parametrize these cross sections to facilitate their use in the calculation of energy deposition by protons and hydrogen atoms in atmospheric gases

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

    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.

  10. Angular dependence of L X-rays emission for Ag by 10 keV electron-impact

    Wang, Xing; Xu, Zhongfeng; Zhang, Ying; Ma, Chao; Zhu, Chengwei

    2016-08-01

    The characteristic X-ray intensities of Ag-Lα, Lβ1, Lβ2 and Lγ1 are measured in electron-impact ionization at energy of 10 keV. The emission angle in this work ranges from 0° to 20° at interval of 5°. The angular dependence of L X-ray intensity ratios has been investigated for Lα / Lβ1, Lβ2 / Lβ1 and Lγ1 / Lβ1. It is found from the experimental results that the emissions of Lβ1, Lβ2 and Lγ1 X-rays are spatially isotropic, while the Lα X-rays exhibit anisotropic emission. Consequently, the alignment behavior of vacancy states is discussed with thorough analysis of vacancy transfer process.

  11. Structural and magnetic properties of zinc ferrite thin films irradiated by 90 keV neon ions

    Gafton, E. V.; Bulai, G.; Caltun, O. F.; Cervera, S.; Macé, S.; Trassinelli, M.; Steydli, S.; Vernhet, D.

    2016-08-01

    The effects of 90 keV neon beam irradiation on the structure and magnetic properties of zinc ferrite thin films have been investigated through several methods, namely, X-ray diffraction technique, Vibrating Sample and SQUID magnetometers. Beforehand, the pristine have also been characterized using profilometry and microscopy techniques. In particular single-phase formation of the thin films deposited on monocrystalline Si (111) substrate by pulsed laser deposition technique was confirmed. Crystal lattice, coercivity, saturation magnetization have been studied for the first time, as a function of ion penetration depth and irradiation fluence. The chemical composition and the crystallinity of the films are not affected with the ion impact acting as a mechanical stress relief. On the contrary, both magnetization and coercivity are sensitive to Neq+ ion irradiation and exhibit different behaviours depending on the ion fluence range.

  12. Bombardment of SiC by 10 keV H+: carbon deposition, surface swelling and changes in surface morphology

    SiC surfaces were bombarded by H+ at 10 keV to total doses ranging from 0.7 to 25 C/cm2 in both high and ultra high vacuum environments. In the former, carbonaceous deposits were observed optically and with AES and electron microprobe analysis. The thickness of these deposits (determined by surface profilometry) increased up to a dose of 3 C/cm2 then remained constant. Surface features were observed on these deposits using SEM. In UHV, no deposit was formed, however surface swelling was observed. Surface features were again observed but were qualitatively different than those observed on the carbonaceous deposits. Several possible explanations for these observations are discussed including, in the case of the carbonaceous deposits, a possible phase change from amorphous to ordered occurring in the vicinity of a 3 C/cm2 dose. (Auth.)

  13. Evaluation of the 1077 keV γ-ray emission probability from 68Ga decay

    68Ga decays to the excited states of 68Zn through the electron capture decay mode. New recommended values for the emission probability of 1077 keV γ-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011, JIANG Li-Yang deduced a new value for 1077 keV γ-ray emission probability by measuring the 69Ga(n, 2n) 68Ga reaction cross section. The new value is about 20% lower than values obtained from previous absolute measurements and evaluations. In this paper, the discrepancies among the measurements and evaluations are analyzed carefully and the new values are re-recommended. Our recommended value for the emission probability of 1077 keV γ-ray is (2.72±0.16)%. (authors)

  14. 7 keV sterile neutrino dark matter from split flavor mechanism

    Ishida, Hiroyuki; Takahashi, Fuminobu

    2014-01-01

    The recently discovered X-ray line at about $3.5\\,$keV can be explained by sterile neutrino dark matter with mass, $m_s \\simeq 7\\,$keV, and the mixing, $\\sin^2 2\\theta \\sim 10^{-10}$. Such sterile neutrino is more long-lived than estimated based on the seesaw formula, which strongly suggests an extra flavor structure in the seesaw sector. We show that one can explain both the small mass and the longevity based on the split flavor mechanism where the breaking of flavor symmetry is tied to the breaking of the $B-L$ symmetry. In a supersymmetric case we find that the $7\\,$keV sterile neutrino implies the gravitino mass about $100\\,$TeV.

  15. The 7 keV axion dark matter and the X-ray line signal

    Higaki, Tetsutaro [KEK, Tsukuba (Japan). Theory Center; Jeong, Kwang Sik [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Takahashi, Fuminobu [Tohoku Univ., Sendai (Japan). Dept. of Physics; Tokyo Univ., Kashiwa (Japan). Kavli IPMU, TODIAS

    2014-03-15

    We propose a scenario where the saxion dominates the energy density of the Universe and reheats the standard model sector via the dilatonic coupling, while its axionic partner contributes to dark matter decaying into photons via the same operator in supersymmetry. Interestingly, for the axion mass m{sub a} ≅ 7 keV and the decay constant f{sub a} ≅10{sup 14-15} GeV, the recently discovered X-ray line at 3.5 keV in the XMM Newton X-ray observatory data can be explained. We discuss various cosmological aspects of the 7 keV axion dark matter such as the production of axion dark matter, the saxion decay process, hot dark matter and isocurvature constraints on the axion dark matter, and the possible baryogenesis scenarios.

  16. Hydrogenation kinetics in oxidized boron-doped silicon irradiated by keV electrons

    Lin, Wallace Wan-Li; Sah, Chih-Tang

    1988-08-01

    Hydrogenation kinetics of boron acceptors in oxidized silicon during and after repeated 8-keV electron irradiation (225-2700-μC/cm2 stresses and 10-168-h interirradiation anneals) at room temperature are reported. Hydrogenation proceeds rapidly during irradiation but continues for many hours after the 8-keV electron beam is removed. Postoxidation process dependencies show that postoxidation and postmetallization annealing processes reduce the hydrogenation effect during the 8-keV electron irradiation, while exposure of the oxide to water prior to aluminum electrode deposition enhances it. The data can be interpreted by our two-reaction model consisting of the hydrogen capture reaction by the boron acceptor and the hydrogen recombination reaction to form hydrogen molecule.

  17. Erosion of volatile elemental condensed gases by keV electron and light-ion bombardment

    Erosion of the most volatile elemental gases by keV electron and light-ion bombardment has been studied at the experimental setup at Risoe. The present work includes frozen neon, argon, krypton, nitrogen, oxygen and three hydrogen isotopes, deuterium, hydrogen deuteride and hydrogen. The yield of these condensed gases has been measured as a function of film thickness and primary energy for almost all combinations of primary particles (1-3 keV electrons, 5-10 keV hydrogen- and helium ions) and ices. These and other existing results show that there are substantial common features for the sputtering of frozen elemental gases. Within the two groups, the solid rare gases and the solid molecular gases, the similarity is striking. The hydrogenic solids deviate in some respects from the other elements. The processes that liberate kinetic energy for the particle ejection in sputtering are characteristic of the specific gas. (au) 3 tabs., 12 ills., 159 refs

  18. Progress in determining keV neutron cross sections with AMS

    This status report deals with the progress in the measurements of keV-neutron cross sections with a combination of the activation technique and accelerator mass spectrometry. The neutron activations were done at the Karlsruhe 3.7 MV Van de Graaff accelerator using the 7Li(p,n)7Be neutron source, and the subsequent AMS measurements performed at the VERA facility in Vienna and the Maier-Leibnitz laboratory in Munich. The (n,γ) cross sections of 9Be, 13C, 235U, and the 14N(n,p) reaction were activated with a quasi-stellar neutron distribution of kT=25 keV and with monoenergetic neutron beams of 140, 220, and 500 keV. Further (n,γ) measurements on 35Cl, 40Ca, 54Fe, 58,62Ni, and 78Se were performed at kT=25 keV and are compared to previous TOF measurements

  19. 7 keV sterile neutrino dark matter from split flavor mechanism

    Ishida, Hiroyuki [Tohoku Univ., Sendai (Japan). Dept. of Physics; Jeong, Kwang Sik [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Takahashi, Fuminobu [Tohoku Univ., Sendai (Japan). Dept. of Physics; Tokyo Univ., Kashiwa (Japan). Kavli IPMU, TODIAS

    2014-02-15

    The recently discovered X-ray line at about 3.5 keV can be explained by sterile neutrino dark matter with mass, m{sub s}≅ 7 keV, and the mixing, sin{sup 2}2θ∝10{sup -10}. Such sterile neutrino is more long-lived than estimated based on the seesaw formula, which strongly suggests an extra flavor structure in the seesaw sector. We show that one can explain both the small mass and the longevity based on the split flavor mechanism where the breaking of flavor symmetry is tied to the breaking of the B-L symmetry. In a supersymmetric case we find that the 7 keV sterile neutrino implies the gravitino mass about 100 TeV.

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

    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.

  1. Optical excitation function of H(1s-2p) produced by electron impact from threshold to 1.8 keV

    James, G.K. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States); Slevin, J.A. [Department of Experimental Physics, St. Patricks College, Maynooth, County Kildare (Ireland); Shemansky, D.E. [Department of Aerospace Engineering, University of Southern California, Los Angeles, California 90089 (United States); McConkey, J.W. [Department of Physics, University of Windsor, Windsor, Ontario, N9B3P4 (CANADA); Bray, I. [Electronic Structure of Materials Centre, The Flinders University of South Australia, G.P.O. Box 2100, Adelaide 5001 (Australia); Dziczek, D. [Institute of Physics, Nicholas Copernicus University, 87-100 Torun (Poland); Kanik, I.; Ajello, J.M. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109 (United States)

    1997-02-01

    The optical excitation function of prompt Lyman-{alpha} radiation, produced by electron impact on atomic hydrogen, has been measured over the extended energy range from threshold to 1.8 keV. Measurements were obtained in a crossed-beams experiment using both magnetically confined and electrostatically focused electrons in collision with atomic hydrogen produced by an intense discharge source. A vacuum-ultraviolet monochromator system was used to measure the emitted Lyman-{alpha} radiation. The absolute H(1s-2p) electron impact excitation cross section was obtained from the experimental optical excitation function by normalizing to the accepted optical oscillator strength, with corrections for polarization and cascade. Our data are significantly different from the earlier experimental results and which are limited to energies below 200 eV. Statistical and known systematic uncertainties in our data range from {plus_minus}4{percent} near threshold to {plus_minus}2{percent} at 1.8 keV. Multistate coupling affecting the shape of the excitation function up to 1 keV impact energy is apparent in both the present experimental data and present theoretical results obtained with convergent close-coupling (CCC) theory. This shape function effect leads to an uncertainty in absolute cross sections at the 10{percent} level in the analysis of the experimental data. The derived optimized absolute cross sections are within 7{percent} of the CCC calculations over the 14 eV{endash}1.8 keV range. The present CCC calculations converge on the Bethe-Fano profile for H(1s-2p) excitation at high energy. For this reason agreement with the CCC values to within 3{percent} is achieved in a nonoptimal normalization of the experimental data to the Bethe-Fano profile. The fundamental H(1s-2p) electron impact cross section is thereby determined to an unprecedented accuracy over the 14 eV {endash} 1.8 keV energy range. (Abstract Truncated)

  2. A new approach for precise measurements of keV neutron capture cross sections: The examples of 93Nb, 103Rh, and 181Ta

    A new experimental method has been implemented for precise measurements of neutron capture cross sections in the energy range from 3 to 200 keV. Neutrons are produced via the 7Li(p,n)7Be reaction using a pulsed 3 MV Van de Graaff accelerator. The neutron energy is determined by the time of flight technique using flight paths of less than 1 m. Capture events are detected with the Karlsruhe 4π Barium Fluoride Detector. This detector is characterized by a resolution in gamma-ray energy of 14% at 662 keV and 7% at 2.5 MeV, a time resolution of 500 ps, and a peak efficiency of 90% at 1 MeV. Capture events are registered with ≅ 95% probability above a gamma-ray threshold of 2.5 MeV. The combined effect of the relatively short primary flight path, the 10 cm inner radius of the detector sphere, and of the low capture cross section of BaF2 allows to discriminate the main background due to capture of sample scattered neutrons in the scintillator via time of flight, leaving part of the neutron energy range completely undisturbed. The high efficiency and good energy resolution for capture gamma-rays yields a further reduction of this background by using only the relevant energy channels for data evaluation. In the first measurements with the new detector, the neutron capture cross sections of 93Nb, 103Rh, and 181Ta were determined in the energy range from 3 to 200 keV relative to gold as a standard. The cross section ratios could be determined with overall systematic uncertainties of 0.7 to 0.8%; statistical uncertainties were less than 1% in the energy range from 20 to 100 keV, if the data are combined in 20 keV wide bins. The necessary sample masses were of the order of one gram. Further improvements with respect to sensitivity and accuracy are discussed. (orig.)

  3. Experiments on transmission sputtering with 100-300 keV noble gas ions on metal films

    The yield and energy spectra of sputtered ions were investigated in the energy range of 100-300 keV with Ne, Ar, Kr ions on aluminium, copper, and silver films of 500-1500 A. The goal of these experiments was to compare the measured yields to Sigmund's theory for transmission sputtering, and to investigate the dependence of the energy spectra on the bombarding ion's energy. The energy dependence of the sputtering yield was studied at one foil thickness for different ion energies, whereby the varying sputtered ion curents were registered. Sigmund's formula S(E1)=const. α' Ssub(n) (E1) (E=exit energy, Ssub(n)=nuclear stopping power of the projectile) proved to be well applicable for sputtered ions in the 100-300 keV range. A scattering experiment and the erosion of a vapor deposited surface on a carrier foil were performed to obtain the factor const. α'. The results of these experiments agreed with Sigmunds theory. The energy spectra of the sputtered ions above E=30eV were fitted by a polynomial with four parameters. At energies above 200 eV, the spectra had the form P(E) approximately Esup(-b), with b approximately 2. No significant change of P(E) with the energy of the projectile was noticed. The following tendency could be noted: beyond the maximum of Ssub(n) (E1), b decreases with decreasing E1 for a fixed projectile, i.e. with increasing stopping power more high energy ions are sputtered. The b values for different metals are approximately equal to those of reflection sputtering experiments. (Auth.)

  4. A high-sensitivity search for a 17keV neutrino

    A negative result for the existence of a 17keV neutrino was obtained by a very high-statistical measurement of the 63Ni β-spectrum and a response function using an iron-free magnetic spectrometer. The obtained mixing strength is vertical stroke Uvertical stroke 2(1.8±3.3(stat.)±3.3(sys.))x10-4, which strongly excludes the existence of a 17keV neutrino with an admixture of 1%. We set the upper limit to 0.095% on vertical stroke Uvertical stroke 2 with a 95% confidence level. (orig.)

  5. Influence of ~7 keV sterile neutrino dark matter on the process of reionization

    Rudakovskiy, Anton; Iakubovskyi, Dmytro

    2016-01-01

    Recent reports of a weak unidentified emission line at ~3.5 keV found in spectra of several matter-dominated objects may give a clue to resolve the long-standing problem of dark matter. One of the best physically motivated particle candidate able to produce such an extra line is sterile neutrino with the mass of ~7 keV. Previous works show that sterile neutrino dark matter with parameters consisting with the new line measurement modestly affects structure formation compared to conventional co...

  6. Bragg concentrators for hard (> 10keV) x-ray astronomy: Status report

    Pareschi, G.; Frontera, F.; Pasqualini, G.

    1997-01-01

    The use of focusing telescopes in hard X-ray (E > 10 keV) astronomy will provide better flux sensitivity and imaging performances with respect to the direct-viewing detectors, utilized until now. We present recent results obtained from our group regarding the possible use of Bragg-diffraction tec......The use of focusing telescopes in hard X-ray (E > 10 keV) astronomy will provide better flux sensitivity and imaging performances with respect to the direct-viewing detectors, utilized until now. We present recent results obtained from our group regarding the possible use of Bragg...

  7. Preliminary Study on Neutron Radiography with Several Hundred keV Fast Neutrons

    Several hundred keV fast neutron radiography (HKFNR) can be a complementary technique to common thermal neutron radiography (TNR) and several MeV fast neutron radiography (MFNR). We tested HKFNR on a 4.5 MV Van de Graaff accelerator, and the experimental results show that the spatial resolution of this technique is better than MFNR and close to TNR. Several hundred keV fast neutrons can penetrate some thermal neutron absorbers such as Cd, and it is feasible to investigate its use on some materials which are transparent to cold/thermal neutrons, such as aluminum, using this technique

  8. Keväällä levitetyn kipsin vaikutukset suorakylvöpellolle

    Alestalo, Laura

    2011-01-01

    Koe keväällä levitetyn kipsin vaikutuksista suorakylvöpellolle tehtiin Pukkilan Torpissa kasvu‎kautena 2010. Kipsikoe toteutettiin yhteistyössä lannoitefirma Yara Suomi Oyj:n kanssa ja se oli ‎osa Yaran ja Tekesin rahoittamaa TraP-projektia, jossa testataan kipsiä fosforikuormituksen ‎hallintaan. Kokeen tavoitteena oli tuottaa kokemuksia TraP-projektille kipsin kevätlevityksestä ‎suorakylvöpellolla ja saada koetuloksia kipsin vaikutuksista maahan sekä kasvuston ravinteiden ‎ottoon.‎ Kokee...

  9. Direct gamma-X spectrometry measurements for energies below 100 keV in environmental samples

    Extending the validity of direct (without radiochemistry) gamma spectrometry measurement below 100 keV is of interest to quantify 234Th, 241Am, 210Pb and 129I. The relative increase of the photoelectric cross-section below 100 keV compared to the Compton one oblige to take into account the self-absorption in the sample. The experimental measurement of the absorption coefficient gives this contribution. Applying to different solid matrices from the environment (soil, sediment, sand, algae, mussels, fishes, terrestrial moss, milk), dried or ashed, results are presented. (authors)

  10. Absolute measurement of 115In capture cross section at 144 and 565 keV

    The cross section of 115In(n, γ) 116mIn reaction are measured at 144 keV and 565 keV neutron energy by activation technique. The neutron fluence is measured by using H2 and CH4 filled proportional counter. A 4πβ counter is used to determine the β activities of 116mIn. The efficiency of the β detector is determined by 4πβ-γ coincidence techniques. A Monte-Carlo program is used to calculate the effect for neutron scattering from target, sample and holder. The results are compared with others

  11. Avalanche photodiodes as large dynamic range detectors for synchrotron radiation

    We investigated silicon-based avalanche photodiodes (APDs) as X-ray detectors in terms of their linearity, maximum counting rates, and dynamic range with 8.4 keV synchrotron radiation. Measurements resulted in counting rates that extend from the APD's noise level of 10-2 Hz to saturation counting rates in excess of 108 Hz. In addition, by monitoring the APD's noise level and photon counting efficiency between synchrotron bursts, we demonstrate nine orders of magnitude dynamic range. ((orig.))

  12. Study of He+-He collisions between 5 and 12 KeV at small angle scattering (0.5 to 30). Improvement to the experimental device: use of a Wien filter

    Doubly differential cross-sections have been determined for direct elastic and inelastic processes arising during the scattering of an He+ ion beam by an He atomic target in the energetic and angular ranges between 5 and 12 keV, 0,50 and 30 respectively

  13. Experimental studies of keV energy neutron-induced reactions relevant to astrophysics and nuclear physics

    Shima, T.; Kii, T.; Kikuchi, T.; Okazaki, F.; Kobayashi, T.; Baba, T.; Nagai, Y. [Tokyo Inst. of Tech. (Japan). Faculty of Science; Igashira, M.

    1997-03-01

    Nuclear reactions induced by keV energy neutrons provide a plenty of informations for studies of both astrophysics and nuclear physics. In this paper we will show our experimental studies of neutron- induced reactions of light nuclei in the keV energy region by means of a pulsed keV neutron beam and high-sensitivity detectors. Also we will discuss astrophysical and nuclear-physical consequences by using the obtained results. (author)

  14. Ionization of atomic hydrogen by 30 1000 keV antiprotons

    Knudsen, H.; Mikkelsen, U.; Paludan, K. [Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C (Denmark); Kirsebom, K.; Moller, S.P.; Uggerhoj, E. [Institute for Synchrotron Radiation, University of Aarhus, DK-8000 Aarhus C (Denmark); Slevin, J. [Department of Experimental Physics, St. Patrick`s College, Maynooth (Ireland); Charlton, M. [Department of Physics and Astronomy, University College London, London WC1E 6BT (United Kingdom); Morenzoni, E. [Paul Scherrer Institut, Villigen, CH-4234 (Switzerland)

    1995-06-05

    Ionization in collisions between antiprotons and atomic hydrogen is perhaps the least complicated and most fundamental process that can be treated by atomic-collision theory. We present measurements of the ionization cross section for 30--1000 keV antiprotons colliding with atomic hydrogen.

  15. Development of a 400 keV multi-stage electrostatic accelerator for neutral beam injectors

    A three-stage electrostatic accelerator has been tested up to 400 keV. The structure of the accelerator is the same as that of the 500 keV accelerator for the JT-60U negative-ion-based neutral beam injection (N-NBI) system. It was confirmed that the heat loads were mainly due to secondary particles generated by the stripping of H- ions in the accelerator, and suppressed effectively by reducing the operational gas pressure. The heat loads at the source pressure of 0.3 Pa, which is the design pressure of the JT-60U ion source, were evaluated to be 3.4 % (the first acceleration grid), 4.3 % (the second acceleration grid) and 2.4 % (the grounded grid) of the input electric power. A H- beam of 0.18 A has been accelerated successfully up to 400 keV for 1 s from 9 apertures. The accelerated H- current density was 13 mA/cm2, the same current density of the JT-60U source. Higher H- beam current of 0.5 A was also obtained at 350 keV from 49 apertures. (orig.)

  16. INTEGRAL 11-year hard X-ray survey above 100 keV

    Krivonos, Roman A; Lutovinov, Alexander A; Revnivtsev, Mikhail G; Churazov, Eugene M; Sunyaev, Rashid A

    2014-01-01

    We present results of all sky survey, performed with data acquired by the IBIS telescope onboard the INTEGRAL observatory over eleven years of operation, at energies above 100 keV. A catalogue of detected sources includes 132 objects. The statistical sample detected on the time-averaged 100-150 keV map at a significance above 5 sigma contains 88 sources: 28 AGNs, 38 LMXBs, 10 HMXBs and 12 rotation-powered young X-ray pulsars. The catalogue includes also 15 persistent sources, which were registered with the significance 4 sigma 12 sigma) in the 17-60 keV energy band. All sources from these two groups are known X-ray emitters, that means that the catalogue has 100% purity in respect to them. Additionally, 29 sources were found in different time intervals. In the context of the survey we present a hardness ratio of galactic and extragalactic sources, a LMXBs longitudinal asymmetry and a number-flux relation for non-blazar AGNs. At higher energies, in the 150-300 keV energy band, 25 sources have been detected wit...

  17. Energy dependence of small silver clusters sputtered by 150 keV Ar+ ions

    The energy distribution of small neutral silver clusters Agn and of positively and negatively charged cluster ions Agn+ and Agn-(n=1–4) sputtered by 150 keV Ar+ ions was investigated. The measured energy distributions asymptotically drop off with E-x, where x increases with cluster size n.

  18. Alpha-Decay of $^{211}Po$ on the 1633 keV $^{207}Pb$ level

    Chumin, V G; Malikov, Sh R; Norseev, Yu V; Samatov, Z K; Fominykh, V I; Cherevatenko, A P; Yurkova, L V

    2000-01-01

    In investigations of gamma-spectrum of ^{211}At and daughter ^{211}Po and ^{207}Bi isotopes a new branch of the alpha-decay on the ^{207}Pb 1633 keV level is discovered. Its intensity is 8.1 cdot 10^{-4} %.

  19. Fragmentation of OCS3+ formed by 150 keV Ar+ ion impact on OCS

    The dissociation of OCS3+ formed in ion impact ionization of OCS has been studied using the technique of multi-ion time of flight mass spectroscopy employing 150 keV Ar+ ions as projectiles. The coincidence plot reveals several fragmentation channels for the decay of this transient molecular ion with different possible decay mechanisms.

  20. Dynamical framework for KeV Dirac neutrino warm dark matter

    Robinson, Dean J.; Tsai, Yuhsin

    2014-08-01

    If the source of the reported 3.5 keV x-ray line is a sterile neutrino, comprising an O(1) fraction of the dark matter (DM), then it exhibits the property that its mass times mixing angle is ˜ few×10-2 eV, a plausible mass scale for the active neutrinos. This property is a common feature of Dirac neutrino mixing. We present a framework that dynamically produces light active and keV sterile Dirac neutrinos, with appropriate mixing angles to be the x-ray line source. The central idea is that the right-handed active neutrino is a composite state, while elementary sterile neutrinos gain keV masses similarly to the quarks in extended technicolor. The entire framework is fixed by just two dynamical scales and may automatically exhibit a warm dark matter (WDM) production mechanism—dilution of thermal relics from late decays of a heavy composite neutrino—such that the keV neutrinos may comprise an O(1) fraction of the DM. In this framework, the WDM is typically quite cool and within structure formation bounds, with temperature ˜ few×10-2Tν and free-streaming length ˜ few kpc. A toy model that exhibits the central features of the framework is also presented.

  1. A Dynamical Framework for KeV Dirac Neutrino Warm Dark Matter

    Robinson, Dean J

    2014-01-01

    If the source of the reported $3.5$ keV x-ray line is a sterile neutrino, comprising an $\\mathcal{O}(1)$ fraction of the dark matter (DM), then it exhibits the property that its mass times mixing angle is $\\sim 10^{-2}$ eV, a plausible mass scale for the active neutrinos. This property is a common feature of Dirac neutrino mixing. We present a framework that dynamically produces light active and keV sterile Dirac neutrinos, with appropriate mixing angles to be the x-ray line source. The central idea is that the right-handed active neutrino is a composite state, while elementary sterile neutrinos gain keV masses similarly to the quarks in extended Technicolor. The entire framework is fixed by just two dynamical scales and automatically exhibits a warm dark matter (WDM) production mechanism -- dilution of thermal relics from late decays of a heavy composite neutrino -- such that the keV neutrinos may comprise an $\\mathcal{O}(1)$ fraction of the DM. In this framework, the WDM is typically quite cool $\\sim 0.02~T...

  2. Calibration of thin-film dosimeters irradiated with 80-120 kev electrons

    Helt-Hansen, J.; Miller, A.; McEwen, M.;

    2004-01-01

    A method for calibration of thin-film dosimeters irradiated with 80-120keV electrons has been developed. The method is based on measurement of dose with a totally absorbing graphite calorimeter, and conversion of dose in the graphite calorimeter to dose in the film dosimeter by Monte Carlo calcul...

  3. 5 (Upgradable to 25 keV) Free Electron Laser (FEL) Facility

    York, R C

    2013-01-01

    A Free Electron Laser (FEL) facility utilizing a recirculated Superconducting Radio Frequency (SRF) linear accelerator (linac) provides the opportunity to achieve about five times greater photon energy than an unrecirculated linac of similar cost. > A 4 GeV SRF, cw, electron linac can be used to drive an FEL producing 5 keV photons. The SLAC National Accelerator Laboratory, a Department of Energy (DOE) Basic Energy Sciences (BES) laboratory, proposes to utilize a 4 GeV unrecirculated, SRF, linac in a segment of existing linac tunnel. > For an initial investment similar to that of the proposed SLAC strategy, a recirculated SRF linac system could deliver the 4 GeV electrons for photon energies of 5 keV and provide an upgrade path to photon energies of 25 keV. > Further support amounting to about a third of the initial investment would provide upgrade funds for additional SRF linac and cryogenic capacity sufficient to provide electron energies appropriate for 25 keV photons matching the European XFEL.

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

    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.

  5. Identification of 3.55 KeV line in the framework of standard physics

    Dubrovich, V K

    2014-01-01

    Identification of the X-ray 3.55 KeV line as a recombination line of $\\pi^-$ tritium mesoatom is proposed. It has been shown that in principle it is possible to form such an atom under standard laboratory conditions, without bringing in new physics.

  6. EITHER keV sterile neutrinos OR quasi-degenerate active neutrinos

    Merle, Alexander

    2012-01-01

    We present a No-Go theorem for keV sterile neutrino Dark Matter: if sterile neutrinos at the keV scale play the role of Dark Matter, they are typically unstable and their decay produces an astrophysical monoenergetic X-ray line. It turns out that the observational bound on this line is so strong that it contradicts the existence of a quasi-degenerate spectrum of active neutrinos in a seesaw type I framework where the Casas-Ibarra matrix R is real. This is the case in particular for models without CP violation. We give a general proof of this theorem. While the theorem (like every No-Go theorem) relies on certain assumptions, the situation under which it applies is still sufficiently general to lead to interesting consequences for keV neutrino model building. In fact, depending on the outcome of the next generation experiments, one might be able to rule out whole classes of models for keV sterile neutrinos.

  7. Energy Reflected from Solid Targets Bombarded keV Protons and Helium Ions

    Andersen, Hans Henrik; Lenskjaer, T.; Sidenius, G.;

    1976-01-01

    The energy‐reflection coefficient γ has been measured for keV protons impinging on Cu, Au, and Pb and helium impinging on Si, Ag, Ta, and Pb. The results are obtained by entirely independent techniques in three different laboratories. They agree within the stated accuracies of 10%. For a given...

  8. Capture in the 1.15-keV iron resonance

    The 1.15-keV resonance in iron is important to reactors in that a major part of the iron capture integral is due to this one resonance. This resonance is also a good test case for capture gamma-ray detectors, which are meant to have an efficiency independent of gamma-ray energy spectra, because this resonance has an unusually hard spectrum and other iron resonances do not. There have been severe discrepancies among different groups who have measured the capture area and transmission of this resonance. A new measurement, employing C6F6 liquid scintillators and pulse-height weighting to effect total energy detection, has been made of the ratio of the capture area of the 22.8-keV resonance relative to that of the 1.15-keV resonance. The 22.8-keV resonance has a relatively soft gamma-ray spectrum and there is agreement on the capture area. The results (2.91 +- 0.17) agree well with transmission measurements and confirm the applicability of total energy detectors for use on capture resonances with very hard capture gamma-ray spectra

  9. Resonance neutron capture in 23Na and 27Al from 3 to 600 keV

    The radiative capture cross sections of 23Na and 27Al were measured with the high resolution facility at the 40 m station of the Oak Ridge Electron Linear Accelerator. Resonance parameters for the individual resonances below 600 keV are given. Particular care was taken to correct the data for prompt neutron scattering effects by Monte Carlo methods

  10. R-matrix analysis of the 239Pu cross sections up to 1 keV

    The results are reported of an R-matrix resonance analysis of the 239Pu neutron cross sections up to 1 keV. After a description of the method of analysis the nearly 1600 resonance parameters obtained are listed and extensive graphical and numerical comparisons between calculated and measured cross-section and transmission date are presented. 47 refs., 47 figs., 8 tabs

  11. 8 to 11 keV x-ray sources for imaging and absorption experiments

    We have measured the 8 to 11 keV emission spectra from plasmas produced by impinging 0.53 μm 100 and 200 ps FWHM Gaussian laser pulses on targets of different materials. The experimental spectra from W and Zn are identified by comparison with local thermodynamic equilibrium plasma emission calculations

  12. An NTD germanium-based microcalorimeter with 3.1 eV energy resolution at 6 keV

    This paper reports recent advances in our microcalorimeter spectrometer that result in an energy resolution of 3.1 eV FWHM for 6 keV X-rays. We have developed a detailed model that indicates that further minor improvements will realize 2 eV FWHM at 6 keV and well under 2 eV at 1 keV. The results demonstrate the value of the microcalorimeter for many applications where a premium exists for very fine resolution in the 0.2-10 keV energy band

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

    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 238U 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 1764 keV. These formulae were used to determine the activities of the 238U, 226Ra, 232Th, 137Cs and 40K 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 238U and 232Th series were applied. The activities obtained in this work were in good agreement with the reference values. - Highlights: • A semi-empirical approach for analyzing the activities of radioactive samples. • HPGe detector-based gamma spectrometers. • Gamma energies from 185 keV to 1764 keV. • Self-attenuation factors of gamma rays for cylindrical sample container. • Coincidence summing corrections for gamma rays in 238U and 232Th series

  14. The Galactic 511 keV line: analysis and interpretation of Integral observations; L'annihilation des positrons galactiques: analyse et interpretation des donnees INTEGRAL

    Lonjou, V

    2005-09-15

    Ever since the discovery of the 511 keV annihilation line emission from the galactic center region in the late seventies, the origin of galactic positrons has been the topic of a vivid scientific debate. It is also one of the prime scientific objectives of the imaging spectrometer SPI on board ESA's INTEGRAL observatory. In this thesis first a description of the most important SPI sub-system is given - the detector plane. Procedures for detector energy calibration and detector degradation analysis are developed. The determination of instrumental background models, a crucial aspect of data analysis, is elaborated. These background models are then applied to deriving sky maps and spectra of unprecedented quality of the Galactic positron annihilation radiation. The emission is centered on the galactic center with a spatial resolution of 8 degrees (FWHM), a second spatial component appears clearly: the galactic disc. The ray energy has been measured with unprecedented accuracy: 511.0 {+-} 0.03 keV for a full width at half maximum (FWHM) of 2.07 {+-} 0.1 keV. The total galactic flux ranges from 1.09 to 2.43 10{sup -3} ph.cm{sup -2}.s{sup -1} including uncertainties on spatial distribution. Finally, the implications of these observations for the production of positrons by various Galactic populations are discussed.

  15. Measurement of flux intensity and epithermal fluence in the neighbourhood of 1 keV (two P-Cu detector method)

    The measurement of epithermal intensity, in the 0.5 to a few tens of eV using conventional resonating detectors: Pu, Lu, In, Au, etc..., is carried out in an energy range which is of little interest from the point of view of radiation damage studies. It is for this reason that we have attempted to measure the flux per unit of lethargy in the region of one keV independently of any consideration concerning the shape of the spectrum, as long it is declining. This method can be summarized as a subtraction: from the total activity of a detector resonating at one keV (copper) is subtracted the activity which does not correspond to its resonances using a second detector whose cross-section is in 1/v (phosphorus). By using B4C as screen it is possible to have a cut-off at about 100 eV and thus to improve the accuracy. It is also shown that a calibration using cobalt allows a direct measurement of the epithermal flux in the keV region. (author)

  16. Detection of 1 - 100 keV x-rays from high intensity, 500 fs laser- produced plasmas using charge-coupled devices

    Dunn, J.; Young, B.K.F.; Conder, A.D.; Stewart, R.E.

    1996-01-01

    We describe a compact, vacuum compatible, large format, charge- coupled device (CCD) camera for scientific imaging and detection of 1- 100 keV x rays in experiments at LLNL JANUS-1ps laser. A standard, front-illuminated, multi-pin phase device with 250 k electron full well capacity, low dark current (10 pA/cm{sup 2} at 20 C) and low read noise (5 electron rms) is cooled to -35 C to give the camera excellent 15-bit dynamic range and signal-to-noise response. Intensity and x-ray energy linear response were determined for optical and x-ray (<65 keV) photons and are in excellent agreement. Departure from linearity was less than 0.7%. Inherent linearity and energy dispersive characteristics of CCD cameras are well suited for hard x-ray photon counting. X-rays absorbed within the depletion and field-free regions can be distinguished by studying the pulse height spectrum. Results are presented for the detection of 1-100 keV Bremsstrahlung continuum, K-shell and L-shell fluorescence spectra emitted from high intensity (10{sup 18}W cm{sup -2}), 500 fs laser- produced plasmas.

  17. KEY COMPARISON: International key comparison of 24 keV neutron fluence measurements (1993-2009): CCRI(III)-K1

    Thomas, D. J.; Lewis, V. E.; Klein, H.; Allisy-Roberts, P. J.

    2010-01-01

    A comparison of 24.5 keV neutron fluence standards was organized by Section III (Neutron Measurements) of the Comité Consultatif des Rayonnements Ionisants, (CCRI). The exercise involved the circulation of a set of three different-diameter Bonner spheres for calibration in fields with energies around 24.5 keV. The fields were produced using four different methods of neutron production. The responses (counts per unit neutron fluence) of the individual spheres were initially determined for the neutron energy of the production method, or methods, employed. To derive the 24.5 keV responses, it was necessary to make corrections for spectral effects, and these were achieved by using response functions for the spheres calculated using the code MCNP. The results demonstrate good consistency within the estimated uncertainties (ranging from about 5% to 10% at the 95% confidence level) between the results reported by all the participants. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCRI Section III, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  18. Performance of a 6 mm thick CdTe detector for 166 keV gamma rays

    McKee, B. T. A.; Goetz, T.; Hazlett, T.; Forkert, L.

    1988-11-01

    In order to extend the utility of CdTe detectors to higher gamma ray energies, yet avoid increasing the charge collection problems of thick detectors, a 6 mm thick detector configuration has been developed consisting of three crystals 2 mm thick and of 16 mm diameter. The active volume is over 1.0 cm 3. The performance of this detector has been evaluated for gamma rays of 166 keV energy by measuring the pulse height spectra and determining the intrinsic peak and total efficiencies over a range of bias voltages and amplifier time constants. A maximum peak and total efficiency of 41% and 80% were obtained with 200 V bias and 2 μs amplifier time constant, although under these conditions the noise width was almost 40 keV FWHM. A Monte Carlo model was used to simulate the gamma ray and electron interaction in this 6 mm detector. Charge collection, including trapping effects, was incorporated into the model. The model pulse height spectra could be approximately matched to the measured data using hole and electron effective mobility values of 60 and 600 cm 2/V s, and hole and electron mean trapping times of 25 and 15 μs. Our findings indicate that detectors such as this will not be useful for high resolution spectroscopic applications, but the high gamma ray stopping power will be of interest for applications where the noise width is acceptable. Results from the modelling imply that in this detector shallow trapping sites (reducing the effective mobility) are more important than deep trapping sites in contributing to incomplete charge collection.

  19. Performance of a 6 mm thick CdTe detector for 166 keV gamma rays

    McKee, B.T.A.; Goetz, T.; Hazlett, T.; Forkert, L.

    1988-11-01

    In order to extend the utility of CdTe detectors to higher gamma ray energies, yet avoid increasing the charge collection problems of thick detectors, a 6 mm thick detector configuration has been developed consisting of three crystals 2 mm thick and of 16 mm diameter. The active volume is over 1.0 cm/sup 3/. The performance of this detector has been evaluated for gamma rays of 166 keV energy by measuring the pulse height spectra and determining the intrinsic peak and total efficiencies over a range of bias voltages and amplifier time constants. A maximum peak and total efficiency of 41% and 80% were obtained with 200 V bias and 2 ..mu..s amplifier time constant, although under these conditions the noise width was almost 40 keV FWHM. A Monte Carlo model was used to simulate the gamma ray and electron interaction in this 6 mm detector. Charge collection, including trapping effects, was incorporated into the model. The model pulse height spectra could be approximately matched to the measured data using hole and electron effective mobility values of 60 and 600 cm/sup 2//V s, and hole and electron mean trapping times of 25 and 15 ..mu..s. Our findings indicate that detectors such as this will not be useful for high resolution spectroscopic applications, but the high gamma ray stopping power will be of interest for applications where the noise width is acceptable. Results from the modelling imply that in this detector shallow trapping sites (reducing the effective mobility) are more important than deep trapping sites in contributing to incomplete charge collection.

  20. Effect of 750 keV Argon ion irradiation on nc ZnO−SiO{sub x} thin films

    Kumar, V.V. Siva, E-mail: vvsk@iuac.res.in

    2015-10-01

    Nanocomposite (nc) ZnO−SiO{sub x} thin films were grown using rf magnetron sputter deposition technique and post-deposition annealing at 750 °C. These films were irradiated with 750 keV Argon ions at fluences in the range from 1 × 10{sup 15} to 1 × 10{sup 17} ions/cm{sup 2}, using Low Energy Ion Beam Facility (LEIBF) at IUAC. X-ray diffraction (XRD) patterns of the as-deposited irradiated films show decrease in intensity of ZnO peaks relative to pristine film. Fourier transform infrared (FT-IR) spectroscopy measurements of the as-deposited irradiated films indicate the breakage of Zn−O, Zn−O−Si and Si−O−Si bonds in them, which is substantiated by FT-IR measurements of 750 °C annealed films that were irradiated at a fluence of 10{sup 16} ions/cm{sup 2}. Photoluminescence (PL) measurements show drastic decrease of visible PL emission from as-deposited irradiated films. Current−Voltage (I–V) measurements show decrease in surface resistance of irradiated films by three orders of magnitude. The results suggest that 750 keV argon ion irradiation of nc ZnO−SiO{sub x} films has resulted in the formation of non-radiative defects in ZnO phase and damage in SiO{sub x}, and amorphization in Zinc silicate phase. These results are explained on the basis of the dominant energy loss mechanism of low energy ions in materials.

  1. SURVIVAL DEPTH OF ORGANICS IN ICES UNDER LOW-ENERGY ELECTRON RADIATION (≤2 keV)

    Icy surfaces in our solar system are continually modified and sputtered with electrons, ions, and photons from solar wind, cosmic rays, and local magnetospheres in the cases of Jovian and Saturnian satellites. In addition to their prevalence, electrons specifically are expected to be a principal radiolytic agent on these satellites. Among energetic particles (electrons and ions), electrons penetrate by far the deepest into the ice and could cause damage to organic material of possible prebiotic and even biological importance. To determine if organic matter could survive and be detected through remote sensing or in situ explorations on these surfaces, such as water ice-rich Europa, it is important to obtain accurate data quantifying electron-induced chemistry and damage depths of organics at varying incident electron energies. Experiments reported here address the quantification issue at lower electron energies (100 eV-2 keV) through rigorous laboratory data analysis obtained using a novel methodology. A polycyclic aromatic hydrocarbon molecule, pyrene, embedded in amorphous water ice films of controlled thicknesses served as an organic probe. UV-VIS spectroscopic measurements enabled quantitative assessment of organic matter survival depths in water ice. Eight ices of various thicknesses were studied to determine damage depths more accurately. The electron damage depths were found to be linear, approximately 110 nm keV–1, in the tested range which is noticeably higher than predictions by Monte Carlo simulations by up to 100%. We conclude that computational simulations underestimate electron damage depths in the energy region ≤2 keV. If this trend holds at higher electron energies as well, present models utilizing radiation-induced organic chemistry in icy solar system bodies need to be revisited. For interstellar ices of a few micron thicknesses, we conclude that low-energy electrons generated through photoionization processes in the interstellar medium could

  2. Effect of 800 keV argon ions pre-damage on the helium blister formation of tungsten exposed to 60 keV helium ions

    Chen, Zhe; Han, Wenjia; Yu, Jiangang; Zhu, Kaigui

    2016-04-01

    This study aims to investigate the effect of Ar8+ ions pre-damage on the following He2+ irradiation behavior of polycrystalline tungsten. We compared the irradiation resistance performance against 60 keV He2+ ions of undamaged tungsten samples with that of pre-damaged samples which were preliminarily exposed to 800 keV Ar8+ ions at a fluence of 4 × 1019 ions m-2. The experimental results indicate that the helium blistering of tungsten could be effectively relieved by the Ar8+ ions pre-damage, while the retention of helium around low energy desorption sites in the pre-damaged tungsten was larger than that of the undamaged samples. A strong orientation dependence of blistering had been observed, with the blister occurred preferentially on the surface of grains with normal direction close to . The Ar8+ ions irradiation-induced damage altered the morphology of helium bubbles in tungsten exposed to the following He2+ irradiation significantly. The intensity of helium release peaks at relatively low temperatures (<600 K) was enhanced due to Ar8+ ions pre-damage.

  3. Study on neutron capture cross sections using the filtered neutron beams of 55 keV and 144 keV at the Dalat reactor and related applications

    In this fundamental research project on nuclear physics in period of 2007, the neutron capture cross sections for the reactions of 146Nd (n,γ) 147Nd, 148Nd (n,γ) 149Nd, 150Nd (n,γ) 151Nd, 154Sm(n,γ) 155Sm, 181Ta (n,γ) 182Ta and total neutron cross section of 181Ta have been measured at the filtered neutron beams of 54 keV and 148 keV of the Dalat nuclear research reactor. The present results were compared with the previous measurements from EXFOR-2003, and the evaluated values of JENDL 3.3 and ENDF/B-6.8. Beside that development computer codes for exact analysis of the buildup and decay of fission products for time following a fission burst, for determination of correction parameters to improve the accuracy in measurements of the neutron capture cross-section on filtered neutron beams and for determination of characteristic parameters of monoenergetic neutron beams were also carried out. (author)

  4. Efficient focusing of 8 keV X-rays with multilayer Fresnel zone plates fabricated by atomic layer deposition and focused ion beam milling

    Mayer, Marcel; Keskinbora, Kahraman; Grévent, Corinne, E-mail: grevent@is.mpg.de [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Szeghalmi, Adriana [Friedrich-Schiller-Universität Jena, Albert-Einstein-Strasse 15, D-07745 Jena (Germany); Knez, Mato [CIC nanoGUNE Consolider, Tolosa Hiribidea 76, E-20018 Donostia-San Sebastian (Spain); Basque Foundation for Science, Alameda Urquijo 36-5, E-48011 Bilbao (Spain); Weigand, Markus [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Snigirev, Anatoly; Snigireva, Irina [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, BP 220, F-38043 Grenoble (France); Schütz, Gisela [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)

    2013-05-01

    The fabrication and performance of multilayer Al{sub 2}O{sub 3}/Ta{sub 2}O{sub 5} Fresnel zone plates in the hard X-ray range and a discussion of possible future developments considering available materials are reported. Fresnel zone plates (FZPs) recently showed significant improvement by focusing soft X-rays down to ∼10 nm. In contrast to soft X-rays, generally a very high aspect ratio FZP is needed for efficient focusing of hard X-rays. Therefore, FZPs had limited success in the hard X-ray range owing to difficulties of manufacturing high-aspect-ratio zone plates using conventional techniques. Here, employing a method of fabrication based on atomic layer deposition (ALD) and focused ion beam (FIB) milling, FZPs with very high aspect ratios were prepared. Such multilayer FZPs with outermost zone widths of 10 and 35 nm and aspect ratios of up to 243 were tested for their focusing properties at 8 keV and shown to focus hard X-rays efficiently. This success was enabled by the outstanding layer quality thanks to ALD. Via the use of FIB for slicing the multilayer structures, desired aspect ratios could be obtained by precisely controlling the thickness. Experimental diffraction efficiencies of multilayer FZPs fabricated via this combination reached up to 15.58% at 8 keV. In addition, scanning transmission X-ray microscopy experiments at 1.5 keV were carried out using one of the multilayer FZPs and resolved a 60 nm feature size. Finally, the prospective of different material combinations with various outermost zone widths at 8 and 17 keV is discussed in the light of the coupled wave theory and the thin-grating approximation. Al{sub 2}O{sub 3}/Ir is outlined as a promising future material candidate for extremely high resolution with a theoretical efficiency of more than 20% for as small an outermost zone width as 10 nm at 17 keV.

  5. Fission cross section measurements of Cm-247, Cf-250 and Es-254 from 0.1 eV to 80 keV

    Fission cross section measurements were made with the RINS system over the neutron energy range from approximately 0.1 eV to 80 keV upon samples of Cm-247, Cf-250 and Es-254. The Cm-247 measurement was undertaken to complete the RINS fission cross section measurement sequence of the curium isotopes, Es-254 was measured because it is a very heavy odd-odd nucleus which might show interesting nuclear structure effects in its fission cross section, and Cf-250 was measured to account for its buildup as a daughter product from the 276-day halflife Es-254. 6 refs., 3 figs

  6. Preliminary measurements of doubly differential cross sections for ejection of electrons from atomic and molecular hydrogen by 70-keV helium ions

    A mixture of atomic and molecular hydrogen, generated by a Slevin hydrogen atom source, was used as the target for 70-keV He+ ions. Procedures were devised to extract the ratio of the cross sections for hydrogen atoms to hydrogen molecules. The cross sections for hydrogen molecules were then measured separately and the cross sections for hydrogen atoms obtained. The cross sections for ejection of electrons, differential in the angle and energy of ejection, were measured over the 15 degrees-160 degrees range of angles and at electron energies from 1.5 to 130 eV

  7. Preliminary measurements of doubly differential cross sections for ejection of electrons from atomic and molecular hydrogen by 70-keV helium ions

    Hsu, Y.Y.; Gealy, M.W.; Kerby, G.W.; Rudd, M.E. [Univ. of Nebraska, Lincoln, NB (United States)

    1993-05-01

    A mixture of atomic and molecular hydrogen, generated by a Slevin hydrogen atom source, was used as the target for 70-keV He{sup +} ions. Procedures were devised to extract the ratio of the cross sections for hydrogen atoms to hydrogen molecules. The cross sections for hydrogen molecules were then measured separately and the cross sections for hydrogen atoms obtained. The cross sections for ejection of electrons, differential in the angle and energy of ejection, were measured over the 15{degrees}-160{degrees} range of angles and at electron energies from 1.5 to 130 eV.

  8. Earth X-ray albedo for cosmic X-ray background radiation in the 1--1000 keV band

    Churazov, E.; Sazonov, S.; Sunyaev, R.; Revnivtsev, M.

    2006-01-01

    We present calculations of the reflection of the cosmic X-ray background (CXB) by the Earth's atmosphere in the 1--1000 keV energy range. The calculations include Compton scattering and X-ray fluorescent emission and are based on a realistic chemical composition of the atmosphere. Such calculations are relevant for CXB studies using the Earth as an obscuring screen (as was recently done by INTEGRAL). The Earth's reflectivity is further compared with that of the Sun and the Moon -- the two oth...

  9. Electron capture by 20-150 keV protons on hydrocarbon gases

    Cross sections are reported for electron capture by 20-150 keV protons incident on CO, CH4, C2H6, and C3H8 target gases. These cross sections were obtained from a new system which measures the proton flux prior to entering and immediately after leaving a differentially pumped gas cell. The absolute magnitude and energy dependence of the values obtained from this apparatus compare favorably with existing measurements where such values are available, the C3H8 values are new to the literature. Attempts to reconcile the hydrocarbon data in terms of generalized additive rules have met with limited success below 70 keV but fail as the projectile velocity increases. (orig.)

  10. Study on the parameters of the scanning system for the 300 keV electron accelerator

    Leo, K. W.; Chulan, R. M., E-mail: leo@nm.gov.my; Hashim, S. A.; Baijan, A. H.; Sabri, R. M.; Mohtar, M.; Glam, H.; Lojius, L.; Zahidee, M.; Azman, A.; Zaid, M. [Malaysian Nuclear Agency, Bangi, 43000 Kajang. Selangor (Malaysia)

    2016-01-22

    This paper describes the method to identify the magnetic coil parameters of the scanning system. This locally designed low energy electron accelerator with the present energy of 140 keV will be upgraded to 300 keV. In this accelerator, scanning system is required to deflect the energetic electron beam across a titanium foil in vertical and horizontal direction. The excitation current of the magnetic coil is determined by the energy of the electron beam. Therefore, the magnetic coil parameters must be identified to ensure the matching of the beam energy and excitation coil current. As the result, the essential parameters of the effective lengths for X-axis and Y-axis have been found as 0.1198 m and 0.1134 m and the required excitation coil currents which is dependenton the electron beam energies have be identified.

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

    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.

  12. Dense high aspect ratio hydrogen silsesquioxane nanostructures by 100 keV electron beam lithography

    Vila-Comamala, Joan; Gorelick, Sergey; Guzenko, Vitaliy A; David, Christian [Paul Scherrer Institut, Villigen CH-5232 (Switzerland); Faerm, Elina; Ritala, Mikko, E-mail: joan.vila@psi.ch [Department of Chemistry, University of Helsinki, Helsinki FI-00014 (Finland)

    2010-07-16

    We investigated the fabrication of dense, high aspect ratio hydrogen silsesquioxane (HSQ) nanostructures by 100 keV electron beam lithography. The samples were developed using a high contrast developer and supercritically dried in carbon dioxide. Dense gratings with line widths down to 25 nm were patterned in 500 nm-thick resist layers and semi-dense gratings with line widths down to 10 nm (40 nm pitch) were patterned in 250 nm-thick resist layers. The dense HSQ nanostructures were used as molds for gold electrodeposition, and the semi-dense HSQ gratings were iridium-coated by atomic layer deposition. We used these methods to produce Fresnel zone plates with extreme aspect ratio for scanning transmission x-ray microscopy that showed excellent performance at 1.0 keV photon energy.

  13. Dense high aspect ratio hydrogen silsesquioxane nanostructures by 100 keV electron beam lithography

    Vila-Comamala, Joan; Gorelick, Sergey; Guzenko, Vitaliy A.; Färm, Elina; Ritala, Mikko; David, Christian

    2010-07-01

    We investigated the fabrication of dense, high aspect ratio hydrogen silsesquioxane (HSQ) nanostructures by 100 keV electron beam lithography. The samples were developed using a high contrast developer and supercritically dried in carbon dioxide. Dense gratings with line widths down to 25 nm were patterned in 500 nm-thick resist layers and semi-dense gratings with line widths down to 10 nm (40 nm pitch) were patterned in 250 nm-thick resist layers. The dense HSQ nanostructures were used as molds for gold electrodeposition, and the semi-dense HSQ gratings were iridium-coated by atomic layer deposition. We used these methods to produce Fresnel zone plates with extreme aspect ratio for scanning transmission x-ray microscopy that showed excellent performance at 1.0 keV photon energy.

  14. Number albedo measurements for backscattered 1250 KeV photons from stratified lead layers

    A new treatment of the stratified combination of lead with other radiation shielding materials for the measurement of number albedo for backscattered 1250 keV photons has been carried out. The stratified combination has been found to attain higher shielding property as well as to acquire a virtual homogeneous entity with a definite effective atomic number. Number albedo measurements have been carried out with indigenously designed Uniform Sensitivity Photon Counter which avoids tedious response correction by inverse matrix method. The results when compared with the theoretically obtained values were found to have better agreement than those obtained experimentally by other workers. The measurements of number albedo values and the angular distribution of backscattered 1250 KeV photons for iron, aluminium and concrete stratified with lead have been reported. (author). 8 figs., 3 tabs., 19 refs

  15. Big-bang nucleosynthesis constraints on light scalars and the 17 keV neutrino hypothesis

    In this paper we present a detailed discussion of the constraints that the primordial abundances of light elements impose on the interactions of light scalars which are relativistic at the time of nulceosynthesis. We discuss the implications of our results for those '17 keV neutrino' models which invoke the presence of Goldstone bosons in order to provide a fast decay or annihilation mechanism for the heavy neutrinos. Although our results can be applied to a variety of cases, we use for our discussion the 'invisible-majoron' scenario. Unless an unnatural tuning of the parameters is considered, we find the scale of spontaneous breaking of lepton number is bounded to be above 19 GeV. While the possibility of a fast decay of the heavy neutrinos into majorons is allowed, we can confidently exclude the annihilation into majorons as a means of depleting the cosmological abundance of stable 17 keV neutrinos. (orig.)

  16. Production of Sterile Neutrino Dark Matter and the 3.5 keV line

    Merle, Alexander

    2014-01-01

    The recent observation of an X-ray line at an energy of $3.5$ keV mainly from galaxy clusters has generated a buzz in the Dark Matter community. If confirmed, this signal could stem from a decaying sterile neutrino of a mass of $7.1$ keV. Such a particle could make up all the Dark Matter, but it is not clear how it was produced in the early Universe. In this paper we show that it is possible to discriminate between different production mechanisms with present-day astronomical data. The most stringent constraint comes from the Lyman-$\\alpha$ forest and seems to disfavor all but one of the main production mechanisms proposed in the literature, which is the production via decay of heavy scalar singlets. Pinning down the production mechanism will help to decide whether the X-ray signal indeed comprises an indirect detection of Dark Matter.

  17. Deriving Models for keV sterile Neutrino Dark Matter with the Froggatt-Nielsen mechanism

    Merle, Alexander

    2011-01-01

    Sterile neutrinos with a mass around the keV scale are an attractive particle physics candidate for Warm Dark Matter. Although many frameworks have been presented in which these neutrinos can fulfill all phenomenological constraints, there are hardly any models known that can explain such a peculiar mass pattern, one sterile neutrino at the keV scale and the other two considerably heavier, while at the same time being compatible with low-energy neutrino data. In this paper, we present models based on the Froggatt-Nielsen mechanism, which can give such an explanation. We explain how to assign Froggatt-Nielsen charges in a successful way, and we give a detailed discussion of all conditions to be fulfilled. It turns out that the typical arbitrariness of the charge assignments is greatly reduced when trying to carefully account for all constraints. We furthermore present analytical calculations of a few simplified models, while quasi-perfect models are found numerically.

  18. Secondary emission monitor for keV ion and antiproton beams

    Sosa, Alejandro; Bravin, Enrico; Harasimowciz, Janusz; Welsch, C P

    2013-01-01

    Beam profile monitoring of low intensity keV ion and antiproton beams remains a challenging task. A Sec- ondary electron Emission Monitor (SEM) has been de- signed to measure profiles of beams with intensities below 107 and energies as low as 20 keV. The monitor is based on a two stage microchannel plate (MCP) and a phosphor screen facing a CCD camera. Its modular design allows two different operational setups. In this contribution we present the design of a prototype and discuss results from measurements with antiprotons at the AEgIS experiment at CERN. This is then used for a characterization of the monitor with regard to its possible future use at different facilities.

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

    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.

  20. 150 keV intense electron beam accelerator system with high repeated pulse

    A 150 keV electron beam accelerator system has been developed for wide application of high power particle beams. The new wire-ion-plasma electron gun has been adopted. The parameters are as follows: Output energy - 130-150 keV; Electron beam density - 250 mA/cm2; Pulse duration - 1 μs; Pulse rate 100 pps; Section of electron beam - 5 x 50 cm2. This equipment can be used to study repeated pulse CO2 laser, to be a preionizer of high power discharge excimer laser and to perform radiation curing process, and so on. The first part contains principle and design consideration. Next is a description of experimental arrangement. The remainder is devoted to describing experimental results and its application

  1. Recent capture cross section data from ORELA above 2.6 keV

    Neutron capture by natural rhodium (103Rh) and enriched stable isotopes of ruthenium (100 to 104) and palladium (104 to 110) were measured at the Oak Ridge Electron Linear Accelerator pulsed neutron facility. Average pure isotope cross sections from three to several hundred keV were derived. The neutron flux shape was determined relative to ENDF/B V standard 6Li(n,α) and 235U(n,f) cross sections below and above 70 keV respectively. Strength functions were adjusted to fit the data by least squares. The 101Ru fission product would appear to cause less poisoning than 105Pd or 103Rh in plutonium fueled fast reactors. 7 references

  2. Thorium resonance-neutron capture (2.6 to 10 keV)

    Individual resonance parameters are fitted to thorium neutron capture data up to 10 keV. The ENDF/B-V resonance parameters (given up to 4 keV) do not describe the data well. An average radiation width GAMMA/sub γ/ = 25.5 +- 1.2 meV is derived together with fitted strength functions 104S0 = (0.86 +- 0.10) eV/sup -1/2/, 104S1 = (1.48 +- 0.07) eV/sup -1/2/, 104S2 = (1.12 +- 0.06) eV/sup -1/2/, and 104GAMMA/sub γ/-bar/D/sub l = 0/ = 14.7 +- 0.5. 2 figures, 2 tables

  3. Recent capture cross section data from ORELA above 2.6 keV

    Neutron capture by natural rhodium (103Rh) and enriched stable isotopes of ruthenium (100 to 104) and palladium (104 to 110) were measured at the Oak Ridge Electron Linear Accelerator pulsed neutron facility. Average pure isotope cross sections from three to several hundred keV were derived. The neutron flux shape was determined relative to ENDF/B V standard 6Li(n,α) and 235U(n,f) cross sections below and above 70 keV respectively. Strength functions were adjusted to fit the data by least squares. The 101Ru fission product would appear to cause less poisoning than 105Pd or 103Rh in plutonium fueled fast reactors

  4. A proton polarimeter for beam energies below 300 keV

    A nuclear polarimeter based on the low energy analyzing power of the 6Li(p, 3He)α reaction has been developed and tested for proton energies below Ep=300 keV. The polarimeter uses a 6LiF target evaporated on a water cooled tantalum backing. The target is observed at backwards angles by four silicon surface barrier detectors. The energy dependence of the analyzing power under 130o for the 6Li(p, 3He)α reaction has been determined down to 200 keV. Spin rotation has been observed via a magnetic field incorporated in a Wien filter demonstrating that the polarimeter is operational. (Author) (7 refs., 7 figs.)

  5. IONIZATION AND FRAGMENTATION OF ANTHRACENE UPON INTERACTION WITH keV PROTONS AND α PARTICLES

    The interaction of keV ions with polyaromatic hydrocarbons is dominated by charge exchange and electronic stopping. We have studied the response of the polyaromatic hydrocarbon anthracene (C14H10) upon keV H+ and He2+ impact using high-resolution time-of-flight mass spectrometry. Extensive fragmentation into small CnH q+m as well as formation of up to triply charged parent ions is observed. Ab initio electron densities are used to calculate the molecular excitation due to electronic stopping. Fragment yields increase with the increase of electronic stopping as a function of projectile velocity. For equal electronic stopping, He2+ is found to induce more fragmentation than H+. The difference in fragmentation is concluded to be due to two electron processes, which are relevant channels only for He2+.

  6. The 871 keV gamma ray from 17O and the identification of plutonium oxide

    Disarmament agreements and discussions between the United States and the Russian Federation for reducing the number of stockpiled nuclear weapons require verification of the origin of materials as having come from disassembled weapons. This has resulted in the identification of measurable 'attributes' that characterize such materials. It has been proposed that the 871 keV gamma ray of 17O can be observed as an indicator of the unexpected presence of plutonium oxide, as opposed to plutonium metal, in such materials. We have shown that the observation of the 871 keV gamma ray is not a specific indicator of the presence of the oxide, but rather indicates the presence of nitrogen

  7. Evaluation of the 2039 keV level property in {sup 124}Te

    Katakura, J. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1997-03-01

    One of the purposes of the mass chain evaluation is to provide reliable level properties of isobars based on available experimental data. In the work of A=124 mass chain evaluation, we have faced some confusing data relating to confirming the level properties of the 2039 keV level in {sup 124}Te: (1) inconsistent intensity ratios of emitted gamma rays between reaction gamma ray and decay gamma ray data, (2) placement of 2039 keV gamma ray transition and (3) gamma ray angular correlation data relating to the level. In the evaluation work, we have to reconcile the confusing data and to provide the adopted ones derived from the available data. In this report, the problems relating to the level properties are described and the reanalyses of the measured data are presented for providing the adopted data. (author)

  8. Investigation of structural stability and magnetic properties of Fe/Ni multilayers irradiated by 300 keV Fe10+

    The effects of irradiation on the structural stability and magnetic properties of Fe/Ni multilayers, which are promising candidate magnet materials in fusion reactors, were investigated. Three types of Fe/Ni multilayers with different modulation periods ranging from 2 nm to 10 nm were deposited on Si (1 0 0) substrate through direct current magnetron sputtering. The multilayered samples were irradiated by 300 keV Fe10+ ions in a wide fluence range of 1.7 × 1018/m2 to 2 × 1019/m2. Magnetic hysteresis loops of pre- and post-irradiation samples were obtained using a vibrating sample magnetometer, and structural stability were analyzed by X-ray diffraction. Magnetic measurements showed that the coercive force of Fe/Ni multilayers remained stable with increasing irradiation fluence. However, saturation magnetization increased with increasing irradiation fluence. The samples with 5 nm modulation period were the least affected by irradiation among the three types of Fe/Ni multilayers. The effects of temperature during irradiation were also discussed to explore the optimum temperature of multilayers

  9. X-ray backlighting sources of 4 to 10 keV for laser-fusion targets

    High-intensity, short-duration x-ray pulses are necessary to diagnose the compression of laser film targets. Present target designs are such that backlighting sources ranging from a few thousand electron volts to 100 keV will be necessary. The desired source durations range from a few tens of picoseconds for flash radiography to several nanoseconds for streaked backlighting, and the source occurrence must be tightly synchronized to that of the target-irradiating laser pulse. For the latter reason, a laser-induced x-ray pulse is preferred. An initial study of the K lines of Ti, Ni, and Zn as possible backlighting sources was conducted. The conversion efficiency of laser light into line radiation was obtained as a function of laser intensity, pulse length, and wavelength. A threshold laser intensity for x-ray line production was identified. Information was obtained on the size and duration of the x-ray emission source, in relation to laser parameters. The experimental results, and their impact on backlighting capability for high-density laser function targets, are discussed

  10. Investigation of the 800 keV Peak in the Gamma Spectrum of Swedish Laplanders

    The gamma spectrum of the body radioactivity in reindeer raising Laplanders has shown a peak at 800 keV, which has not been discussed before in connection with whole body counting. We present here an investigation that was made to be able to identify the isotope. The result is that the peak comes from cesium 134. The possibility to find cesium 134 in fallout is discussed

  11. Effects of uranium bombardment by 20-40 KeV argon ions, Annex 2

    This paper shows the results of argon ions interaction with the polycrystal natural uranium. Thin foil of uranium about 200 μ was bombarded by 20-40 KeV argon ions. Coefficients of cathode scattering δ and secondary electrons emission γ were measured, during the process A+ →U. The foil was then studied by transmission method and method of single step replica using an electron microscope

  12. Design study of 500 keV H- accelerator for ITER NB system

    In the neutral beam (NB) system for heating and current drive of ITER, detailed designs of a five stage Multi Aperture and Multi Grid (MAMuG) accelerator to produce 1 MeV 40 A D- and 870 keV 46 A H- ion beams are ongoing. However, it was expected that shinethrough power from the 870 keV H0 beam was above tolerable level for the maximum plasma density prior to any H mode. Therefore, it was required to reduce the beam energy to 500 keV with maintaining high beam current. The objective of this study is to identify necessary modifications from the original five stage accelerator to a three stage accelerator to produce 500 keV H- ion beam through the physics design based on a beam optics, a beamlet steering and a stripping loss of negative ions. In the beam optics study utilizing a 2D beam analysis code, necessary modifications in aperture diameter, grid thickness and grid spacing were proposed. In a 3D multi beamlets analysis, aperture offsets in the ESG (Electron Suppression Grid) to compensate beamlet deflections and another aperture offset in the GRG (GRounded Grid) to steer the beamlets to a focal point were designed. In a 3D gas flow analysis, it was confirmed that stripping loss of negative ions was not changed and gas density around the beam source satisfied a design requirement for high voltage holding in a modified accelerator configuration proposed in the beam optics study. Finally, the items for modification were summarized. (author)

  13. The 511 keV emission from positron annihilation in the Galaxy

    Prantzos, N.; Boehm, C.; Bykov, A. M.; Diehl, R.; Ferriere, K.; Guessoum, N.; Jean, P.; Knoedlseder, J.; Marcowith, A.; Moskalenko, I. V.; Strong, A.; Weidenspointner, G. [CNRS, UMR7095, UMPC and Institut d' Astrophysique de Paris, F-75014, Paris (France) and LAPP, 9 Chemin de Bellevue, BP 110 F-74941 Annecy-le-Vieux (France); A. F. Ioffe Institute of Physics and Technology, Russian Academy of Sciences, 194021, St. Petersburg (Russian Federation); Max Planck Institut fuer Extraterrestrische Physik, D-85741 Garching (Germany); Laboratoire d' Astrophysique de Toulouse-Tarbes, Universite de Toulouse, CNRS, 14 avenue Edouard Belin, F-31400 Toulouse (France); American University of Sharjah, College of Arts and Sciences/Physics Department, P.O. Box 26666, Sharjah (United Arab Emirates); CESR, Universite de Toulouse, CNRS, 9, Avenue du Colonel Roche, Boite Postal 4346, F-31028 Toulouse Cedex 4 (France); L.U.P.M., Universite Montpellier II, CNRS, Place Eugene Bataillon, F-34095 Montpellier (France); Hansen Experimental Physics Laboratory and Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, Stanford, California 94305 (United States); Max Planck Institut fuer Extraterrestrische Physik, D-85741, Garching (Germany); Max Planck Institut fur Extraterrestrische Physik, Garching, D-85741 Germany, and MPI Halbleiterlabor, Otto-Hahn-Ring 6, D-81739 Muenchen (Germany)

    2011-07-01

    The first {gamma}-ray line originating from outside the Solar System that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990s with OSSE/CGRO (Oriented Scintillation Spectrometer Experiment on GRO satellite/Compton Gamma Ray Observatory) showed that the emission is strongly concentrated toward the Galactic bulge. In the 2000s, the spectrometer SPI aboard the European Space Agency's (ESA) International Gamma Ray Astrophysics Laboratory (INTEGRAL) allowed scientists to measure that emission across the entire Galaxy, revealing that the bulge-to-disk luminosity ratio is larger than observed at any other wavelength. This mapping prompted a number of novel explanations, including rather ''exotic'' ones (e.g., dark matter annihilation). However, conventional astrophysical sources, such as type Ia supernovae, microquasars, or x-ray binaries, are still plausible candidates for a large fraction of the observed total 511 keV emission of the bulge. A closer study of the subject reveals new layers of complexity, since positrons may propagate far away from their production sites, making it difficult to infer the underlying source distribution from the observed map of 511 keV emission. However, in contrast to the rather well-understood propagation of high-energy (>GeV) particles of Galactic cosmic rays, understanding the propagation of low-energy ({approx}MeV) positrons in the turbulent, magnetized interstellar medium still remains a formidable challenge. The spectral and imaging properties of the observed 511 keV emission are reviewed and candidate positron sources and models of positron propagation in the Galaxy are critically discussed.

  14. Ruling out the light WIMP explanation of the galactic 511 keV line

    Wilkinson, Ryan J; Boehm, Celine; McCabe, Christopher

    2016-01-01

    Over the past few decades, an anomalous 511 keV gamma-ray line has been observed from the centre of the Milky Way. Dark matter (DM) in the form of light (< 10 MeV) WIMPs annihilating into electron-positron pairs has been one of the leading hypotheses of the observed emission. Here we show that this explanation is ruled out by the latest cosmological data, suggesting an astrophysical or more exotic DM source of the signal.

  15. New measurement of the relative scintillation efficiency of xenon nuclear recoils below 10 keV

    Aprile, E.; Baudis, L.; Choi, B.; Giboni, K L; Lim, K. E.; Manalaysay, A.; Monzani, M E; Plante, G.; Santorelli, R.; Yamashita, M

    2009-01-01

    Liquid xenon is an important detection medium in direct dark matter experiments, which search for low-energy nuclear recoils produced by the elastic scattering of WIMPs with quarks. The two existing measurements of the relative scintillation efficiency of nuclear recoils below 20 keV lead to inconsistent extrapolations at lower energies. This results in a different energy scale and thus sensitivity reach of liquid xenon dark matter detectors. We report a new measurement of the relative scinti...

  16. Picosecond x-ray measurements from 100 eV to 30 keV

    Attwood, D.T.; Kauffman, R.L.; Stradling, G.L.

    1980-10-15

    Picosecond x-ray measurements relevant to the Livermore Laser Fusion Program are reviewed. Resolved to 15 picoseconds, streak camera detection capabilities extend from 100 eV to higher than 30 keV, with synchronous capabilities in the visible, near infrared, and ultraviolet. Capabilities include automated data retrieval using charge coupled devices (CCD's), absolute x-ray intensity levels, novel cathodes, x-ray mirror/reflector combinations, and a variety of x-ray imaging devices.

  17. Study of avalanche photodiodes for soft X-ray detection below 20keV

    The performance of the large area reach-through avalanche photodiode (APD), manufactured by Hamamatsu Photonics, K.K. as a high resolution X-ray detector is presented. The mentioned APD has an area of 3mm, a fast time response for signal carrier collection and its thick depletion layer of 130μm shows a potential to be used as an effective X-ray absorber below 20keV. Having a capacitance of ∼10pF and a low dark current of 5nA for a gain of 15, at room temperature, this APD had demonstrated one of the best energy resolutions within this kind of devices: 6.4% (FWHM) for 5.9keV photons with a minimum detectable energy of 0.3keV, measured at -20 deg. C. The experiments for the timing property were made in a synchrotron beam facility using an 8keV X-ray beam; the reached count rate was above 108 counts/s, corresponding to a very short dead time of 4.5ns/pulse. In order to test the radiation hardness of the APD, the device was irradiated at a Ring Cyclotron Facility with a 53.5MeV proton beam. The total dose was of 11.3krad and no fatal damage was found in the APD, although the dark current of the APD had shown an increase of one order of magnitude. Finally, the obtained results allow us to affirm that the reach-through APD has the potential to become an excellent X-ray detector, especially in the space mission application

  18. Study of avalanche photodiodes for soft X-ray detection below 20 keV

    Yatsu, Y.; Kuramoto, Y.; Kataoka, J.; Kotoku, J.; Saito, T.; Ikagawa, T.; Sato, R.; Kawai, N.; Kishimoto, S.; Mori, K.; Kamae, T.; Ishikawa, Y.; Kawabata, N.

    2006-08-01

    The performance of the large area reach-through avalanche photodiode (APD), manufactured by Hamamatsu Photonics, K.K. as a high resolution X-ray detector is presented. The mentioned APD has an area of 3 mm ∅, a fast time response for signal carrier collection and its thick depletion layer of 130 μm shows a potential to be used as an effective X-ray absorber below 20 keV. Having a capacitance of ˜10 pF and a low dark current of 5 nA for a gain of 15, at room temperature, this APD had demonstrated one of the best energy resolutions within this kind of devices: 6.4% (FWHM) for 5.9 keV photons with a minimum detectable energy of 0.3 keV, measured at -20C. The experiments for the timing property were made in a synchrotron beam facility using an 8 keV X-ray beam; the reached count rate was above 108 counts/s, corresponding to a very short dead time of 4.5 ns/pulse. In order to test the radiation hardness of the APD, the device was irradiated at a Ring Cyclotron Facility with a 53.5 MeV proton beam. The total dose was of 11.3 krad and no fatal damage was found in the APD, although the dark current of the APD had shown an increase of one order of magnitude. Finally, the obtained results allow us to affirm that the reach-through APD has the potential to become an excellent X-ray detector, especially in the space mission application.

  19. Picosecond x-ray measurements from 100 eV to 30 keV

    Picosecond x-ray measurements relevant to the Livermore Laser Fusion Program are reviewed. Resolved to 15 picoseconds, streak camera detection capabilities extend from 100 eV to higher than 30 keV, with synchronous capabilities in the visible, near infrared, and ultraviolet. Capabilities include automated data retrieval using charge coupled devices (CCD's), absolute x-ray intensity levels, novel cathodes, x-ray mirror/reflector combinations, and a variety of x-ray imaging devices

  20. Energy reflection from gold bombarded with keV protons at various angles of incidence

    The calorimetric deuterium film method operating at liquid-helium temperature was used for measuring the energy reflection coefficient γ for 1--10-keV protons incident on gold at angles of incidence up to 75degree. H+2 and H+3 ions were used to obtain the lowest velocities. The growth with angle increases with energy. There is fair agreement with the theoretical results of Robinson and of Oen and Robinson

  1. Development of a flat-field spectrograph with a wide-band multilayer grating and prefocusing mirror covering 2-4 keV

    A flat-field spectrograph equipped with a wide-band multilayer grating and prefocusing mirror covering 2–4 keV without any mechanical movement has been developed. To realize this, a new multilayer structure consisting of W and B4C layers has been invented, which enhances the diffraction efficiency of the grating over the whole energy range at a fixed angle of incidence as well as the reflectivity of the prefocusing mirror. The multilayer has been deposited on a laminar-type varied-line-spacing holographic replica grating and a spherical mirror substrate. The diffraction efficiency of the multilayer grating varies between 1.2% and 3.3% at 88.65° in the 2.1–4.0 keV range. Also the reflectivity of the prefocusing mirror varies between 2.7% and 12% at 88.00° in the same range. The overall throughput of the spectrograph with the multilayer optics is 104 times higher than that of gold-coated optics.

  2. Photoneutron spectrum of lead following excitation by 8999, 8533, and 8120 keV photons

    The photoneutron spectrum of natural lead has been observed for photoexcitation energies of 8999, 8533, and 8120 keV using a high-resolution 3He ionization chamber. The photons were obtained from the (n, γ) reaction on a nickel target positioned in a nuclear reactor. The Q values for the three reactions 208Pb(γ, n)207Pb, 207Pb (γ, n)206Pb, and 206Pb(γ, n)205Pb have been determined and are, respectively, 7369 +- 5, 6743 +- 3, and 8087 +- 3 keV. Neutron groups corresponding to different final states following excitation by one of the three photon components have been observed and their partial cross sections are reported. The distribution and some systematics of the neutron reduced widths have been studied. The absolute cross sections of the reaction208Pb(γ, n)207Pb at 8999 and 8533 keV photon energies have been found to be 6.8 +- 2.9 and 5.0 +- 2.1 mb, respectively

  3. Momentum mapping spectrometer for probing the fragmentation dynamics of molecules induced by keV electrons

    We describe a new experimental setup for studying the fragmentation dynamics of molecules induced by the impact of keV electrons using the well-known technique of recoil ion momentum spectroscopy. The apparatus consists of mainly a time- and position-sensitive multi-hit particle detector for ion analysis and a channel electron multiplier detector for detecting the ejected electrons. Different components of the setup and the relevant electronics for data acquisition are described in detail with their working principles. In order to verify the reliable performance of the setup, we have recorded the collision-induced ionic spectra of the CO2 molecule by the impact of keV electrons. Information about the ion pairs of CO+:O+, C+:O+ and O+:O+ resulting from dissociative ionizing collisions of 20 and 26 keV electrons with a dilute gaseous target of CO2 molecules has been obtained. Under conditions of the present experiment, the momentum resolutions of the spectrometer for the combined momenta of CO+ and O+ ions in the direction of the time-of-flight axis and perpendicular to the direction of an electron beam are found to be 10.0 ± 0.2 and 15.0 ± 0.3 au, respectively

  4. Development of 120 keV 10 MW neutral beam teststand

    This is a report of design and construction of 120 keV, 10 MW Neutral Beam Test Stand (10 MW NBTS) which has been prepared for the development of NB Injector on R-project in the 1981 to 1982 fiscal year. The Test Stand is designed to simulate NBI on the project and the aim is test for the performance of many components and the over all performance of beam line. A design of the beam line (which is composed of a neutralizer cell, a 180 deg deflection magnet, calorimeter, and ion dump, etc.), 1/4 size ion source, power supply system, and sequence and control are described, and the test results are also given briefly. Main features of the NBTS are as follows: (1) A powerful ion source of 120 keV, 75 A for 1 sec, (2) Gate Turn Off (G.T.O.) accel power supply system of 120 kV, 10 MW, in which all the components are fabricated by the solid-state elements, (3) highspeed open-type cryocondensation pump for the vacuum system. Test results of each component are compared with the design value of them. Overall test including the beam extraction of up to 120 keV, ∼ 20 A for 1 sec is satisfactorily completed by applying 1/4 size model ion source. (author)

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

    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.

  6. Influence of ~7 keV sterile neutrino dark matter on the process of reionization

    Rudakovskiy, Anton

    2016-01-01

    Recent reports of a weak unidentified emission line at ~3.5 keV found in spectra of several matter-dominated objects may give a clue to resolve the long-standing problem of dark matter. One of the best physically motivated particle candidate able to produce such an extra line is sterile neutrino with the mass of ~7 keV. Previous works show that sterile neutrino dark matter with parameters consisting with the new line measurement modestly affects structure formation compared to conventional cold dark matter scenario. In this work, we concentrate on contribution of the sterile neutrino dark matter to the process of reionization. By incorporating dark matter power spectra for ~7 keV sterile neutrinos into extended semi-analytical 'bubble' model of reionization we obtain that such a dark matter would produce significantly sharper reionization compared to widely used cold dark matter models, impossible to 'imitate' within the cold dark matter scenario under any reasonable choice of our model parameters, and would ...

  7. Searching for keV Sterile Neutrino Dark Matter with X-Ray Microcalorimeter Sounding Rockets

    Figueroa-Feliciano, E.; Anderson, A. J.; Castro, D.; Goldfinger, D. C.; Rutherford, J.; Eckart, M. E.; Kelley, R. L.; Kilbourne, C. A.; McCammon, D.; Morgan, K.; Porter, F. S.; Szymkowiak, A. E.; XQC Collaboration

    2015-11-01

    High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field of view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates l=165°,b=-5° with an effective exposure of 106 s, obtaining a limit on the sterile neutrino mixing angle of {{sin}}22θ < 7.2× {10}-10 at 95% CL for a 7 keV neutrino. Better sensitivity at the level of {{sin}}22θ ∼ 2.1× {10}-11 at 95% CL for a 7 keV neutrino is achievable with future 300-s observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.

  8. 1974 view into the cage of the 520 keV electrostatic preaccelerator of Linac 1

    1974-01-01

    The condenser of the high voltage circuit (column in the foreground) is being serviced by Jean Luc Vallet. Standing on the electronics platform (the big, open metallic structure on insulating pillars, for details see 7403120) is Bob Nettelton. The column at the right edge of the photo is part of the bouncer (see also 7403066X) which compensated the voltage drop during acceleration of a proton pulse. In the background is the source (open pill box structure) attached to the accelerating column, barely visible) behind. The "old" 50 MeV Linac 1, the original PS injector built in the 1950s, was (since 1976) replaced by a new 50 MeV linac (Linac 2) with a 750 keV "Cockcroft-Walton" pre-injector(see 7602012X), later replaced by a 750 keV Radio Frequency Quadrupole (RFQ) preaccelerator. Linac 1 co-existed until mid 1992 (from 1982 onwards it was mainly used to inject "test-particles" into the Low Energy Antiproton ring LEAR). In 1984 the electrostatic preaccelerator of linac 1 was replaced by a 520 keV RFQ ( 8303511X...

  9. Searching for keV Sterile Neutrino Dark Matter with X-ray Microcalorimeter Sounding Rockets

    Figueroa-Feliciano, Enectali; Castro, Daniel; Goldfinger, David C; Rutherford, John; Eckart, Megan E; Kelley, Richard L; Kilbourne, Caroline A; McCammon, Dan; Morgan, Kelsey; Porter, Frederick Scott; Szymkowiak, Andrew E

    2015-01-01

    High-resolution X-ray spectrometers onboard suborbital sounding rockets can search for dark matter candidates that produce X-ray lines, such as decaying keV-scale sterile neutrinos. Even with exposure times and effective areas far smaller than XMM-Newton and Chandra observations, high-resolution, wide field-of-view observations with sounding rockets have competitive sensitivity to decaying sterile neutrinos. We analyze a subset of the 2011 observation by the X-ray Quantum Calorimeter instrument centered on Galactic coordinates l = 165, b = -5 with an effective exposure of 106 seconds, obtaining a limit on the sterile neutrino mixing angle of sin^2(2 theta) < 7.2e-10 at 95% CL for a 7 keV neutrino. Better sensitivity at the level of sin^2(2 theta) ~ 2.1e-11 at 95\\% CL for a 7 keV neutrino is achievable with future 300-second observations of the galactic center by the Micro-X instrument, providing a definitive test of the sterile neutrino interpretation of the reported 3.56 keV excess from galaxy clusters.

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

    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.

  11. DARK MATTER SEARCH USING CHANDRA OBSERVATIONS OF WILLMAN 1 AND A SPECTRAL FEATURE CONSISTENT WITH A DECAY LINE OF A 5 keV STERILE NEUTRINO

    We report the results of a search for an emission line from radiatively decaying dark matter in the Chandra X-ray Observatory spectrum of the ultra-faint dwarf spheroidal galaxy Willman 1. 99% confidence line flux upper limits over the 0.4-7 keV Chandra bandpass are derived and mapped to an allowed region in the sterile neutrino mass-mixing angle plane that is consistent with recent constraints from Suzaku X-ray Observatory and Chandra observations of the Ursa Minor and Draco dwarf spheroidals. A significant excess to the continuum, detected by fitting the particle-background-subtracted source spectrum, indicates the presence of a narrow emission feature with energy 2.51 ± 0.07(0.11) keV and flux [3.53 ± 1.95(2.77)] x 10-6 photons cm-2 s-1 at 68% (90%) confidence. Interpreting this as an emission line from sterile neutrino radiative decay, we derive the corresponding allowed range of sterile neutrino mass and mixing angle using two approaches. The first assumes that dark matter is solely composed of sterile neutrinos, and the second relaxes that requirement. The feature is consistent with the sterile neutrino mass of 5.0 ± 0.2 keV and a mixing angle in a narrow range for which neutrino oscillations can produce all of the dark matter and for which sterile neutrino emission from the cooling neutron stars can explain pulsar kicks, thus bolstering both the statistical and physical significance of our measurement.

  12. Correlation between electrical transport, microstructure and room temperature ferromagnetism in 200 keV Ni{sup 2+} ion implanted zinc oxide (ZnO) thin films

    Joshi, B. [Gautam Buddha University, Department of Applied Sciences, Greater Noida (India); Ghosh, S.; Srivastava, P. [Indian Institute of Technology Delhi, Nanostech Laboratory, New Delhi (India); Kumar, P.; Kanjilal, D. [Aruna Asaf Ali Marg, Inter University Accelerator Centre, New Delhi (India)

    2012-05-15

    We report variable temperature resistivity measurements and mechanisms related to electrical conduction in 200 keV Ni{sup 2+} ion implanted ZnO thin films deposited by vapor phase transport. The dc electrical resistivity versus temperature curves show that all polycrystalline ZnO films are semiconducting in nature. In the room temperature range they exhibit band conduction and conduction due to thermionic emission of electrons from grain boundaries present in the polycrystalline films. In the low temperature range, nearest neighbor hopping (NNH) and variable range hopping (VRH) conduction are observed. The detailed conduction mechanism of these films and the effects of grain boundary (GB) barriers on the electrical conduction process are discussed. An attempt is made to correlate electrical conduction behavior and previously observed room temperature ferromagnetism of these films. (orig.)

  13. 58Ni + n transmission, differential elastic scattering and capture measurements and analysis from 5 to 813 keV

    High-resolution neutron measurements for 58Ni-enriched targets were made at the Oak Ridge Electron Linear Accelerator (ORELA) from 100 eV to ∼20 MeV in transmission, from 10 keV to 5 MeV in differential elastic, and from 2.5 keV to 5 MeV in capture. The transmission data were analyzed from 10 to 813 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 10- to 813-keV region as well as a possible parameterization for resonances external to that region to describe the smooth cross section from 10 to 813 keV. The differential elastic data at different scattering angles were compared to theoretical calculations from 30 to 813 keV using an R-matrix code 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, and comparison with the data then provided spin and parity assignments for most of these resonances. the capture data were analyzed from 5 to 450 keV with a least-squares fitting code using the Breit-Wigner formula. In this energy region 30% more resonances were observed in the capture data than in the transmission data. 55 refs., 44 figs., 3 tabs

  14. Radial Profile of the 3.55 keV line out to $R_{200}$ in the Perseus Cluster

    Franse, Jeroen; Bulbul, Esra; Foster, Adam; Boyarsky, Alexey; Markevitch, Maxim; Bautz, Mark; Iakubovskyi, Dmytro; Loewenstein, Mike; McDonald, Michael; Miller, Eric; Randall, Scott W.; Ruchayskiy, Oleg; Smith, Randall K.

    2016-01-01

    The recent discovery of the unidentified emission line at 3.55 keV in galaxies and clusters has attracted great interest from the community. As the origin of the line remains uncertain, we study the surface brightness distribution of the line in the Perseus cluster since that information can be used to identify its origin. We examine the flux distribution of the 3.55 keV line in the deep Suzaku observations of the Perseus cluster in detail. The 3.55 keV line is observed in three concentric an...

  15. Validation of modelled imaging plates sensitivity to 1-100 keV x-rays and spatial resolution characterisation for diagnostics for the "PETawatt Aquitaine Laser"

    Boutoux, G.; Batani, D.; Burgy, F.; Ducret, J.-E.; Forestier-Colleoni, P.; Hulin, S.; Rabhi, N.; Duval, A.; Lecherbourg, L.; Reverdin, C.; Jakubowska, K.; Szabo, C. I.; Bastiani-Ceccotti, S.; Consoli, F.; Curcio, A.; De Angelis, R.; Ingenito, F.; Baggio, J.; Raffestin, D.

    2016-04-01

    Thanks to their high dynamic range and ability to withstand electromagnetic pulse, imaging plates (IPs) are commonly used as passive detectors in laser-plasma experiments. In the framework of the development of the diagnostics for the Petawatt Aquitaine Laser facility, we present an absolute calibration and spatial resolution study of five different available types of IP (namely, MS-SR-TR-MP-ND) performed by using laser-induced K-shell X-rays emitted by a solid silver target irradiated by the laser ECLIPSE at CEntre Lasers Intenses et Applications. In addition, IP sensitivity measurements were performed with a 160 kV X-ray generator at CEA DAM DIF, where the absolute response of IP SR and TR has been calibrated to X-rays in the energy range 8-75 keV with uncertainties of about 15%. Finally, the response functions have been modeled in Monte Carlo GEANT4 simulations in order to reproduce experimental data. Simulations enable extrapolation of the IP response functions to photon energies from 1 keV to 1 GeV, of interest, e.g., for laser-driven radiography.

  16. Radiation-induced effects in MgO single crystal by 200 keV and 1 MeV Ni ion implantation

    Takahashi, Ryohei; Nakai, Yoshihiro; Hamaguchi, Dai [Kyoto Inst. of Tech. (Japan)] [and others

    1997-03-01

    MgO(100) single crystals were implanted with 1.0 MeV and 200 keV Ni ions between 10{sup 15} and 10{sup 17} ions/cm{sup 2} at room temperature. Before and after thermal annealing the radiation damage and the lattice location of implanted Ni ions were analyzed by using Rutherford backscattering spectrometry with channeling and optical absorption measurements. For 1.0 MeV Ni ions, the disorder of Mg atoms increased slowly with ion dose near surface region, while it increased sharply and saturated with ion dose from 2x10{sup 16} ions/cm{sup 2} near ion range. The radiation damage was recovered and implanted Ni ions diffused to the whole of crystal and occupied substitutional positions after 1400degC annealing. For 200 keV Ni ions, the disorder of Mg atoms increased with dose near ion range and had a maximum at about 5x10{sup 16} ions/cm{sup 2}. This tendency agrees with the behavior of color centers obtained from optical measurements. For thermal annealing the radiation damage did not change during 500degC annealing, but the aggregate centers appeared after 300degC annealing. (author)

  17. Contribution to the measurement of the reflection coefficient for curved crystals between 50 and 80 keV; Contribution a la mesure du coefficient de reflexion de cristaux courbes entre 50 keV et 80 keV

    Chartier, J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-09-01

    In the first part, we summarize the main approximate theories dealing with the diffraction of electromagnetic radiation by the crystalline medium, allowing the determination of the characteristic properties of flat and bent crystals used in X and gamma-Ray spectroscopy ('Laue Case'). We describe the experimental setting and we explain our method to measure {gamma}: reflectivity of elastically or plastically bent-crystals from narrow wave-length intervals in the continuous X-Ray spectrum. We discuss our experimental results obtained with different crystals (quartz (3140), Al (200), FLi (200) and compare them with theoretical ones. Finally, we refer to a use of the bent-crystal spectrometer (Cauchois arrangement) in dosimetry. (author) [French] Dans la premiere partie, nous resumons les principales approximations theoriques qui traitent la diffraction du rayonnement electromagnetique par le milieu cristallin et permettent de determiner les grandeurs caracteristiques des lames cristallines planes ou courbees utilisees 'par transmission' en spectroscopie X ou gamma. Apres avoir decrit le montage experimental, nous exposons la methode de mesure de {gamma}: coefficient de reflexion de cristaux courbes (elastiquement ou plastiquement). Le domaine energetique etudie est voisin de 100 keV. Dans cette methode, nous n'utilisons pas des rayonnements monoenergetiques provenant de transitions atomiques ou nucleaires mais des bandes etroites d'energie appartenant au spectre continu du rayonnement emis par un tube a rayons X. Les resultats experimentaux obtenus avec differents cristaux (quartz (3140), Al (200), FLi (200)) sont discutes et compares a ceux prevus par la theorie. Nous mentionnons, enfin, une application en dosimetrie du spectrographe a cristal couche (Geometrie Cauchois). (auteur)

  18. Statistical analysis of ripple morphology on Si surfaces due to 60 keV Ar+-ions

    We report on analysis of ion-beam patterned surface morphology in terms of regularity of pattern shape and orientation, homogeneity over irradiated surface, and the effective increment in its surface area, which are critical in deciding the applications for the corresponding surface. As a case study, we have chosen Si surface, which is exposed to 60 keV Ar+-ions at different angles of incidence and ion fluence and have performed detail statistical analysis of topographic images of the patterned surfaces. By using the Scanning Probe Image Processor (SPIP) software, morphological parameters, viz. surface area ratio, texture direction index, texture aspect ratio, ratio of system correlation length to ripple wavelength, directional roughness exponents, and anisotropy ratio are calculated as functions of ion incidence angle and fluence. From angle-dependent studies, we observe that ripple patterns become more regular with increasing angle of incidence. On the other hand, fluence-dependent study of these parameters shows that ripple shapes are most regular for the fluence of 3 × 1018 ions cm−2, while ripples are most unidirectional for the fluence of 2 × 1018 ions cm−2. Our analysis method shows a route towards optimization of ion-patterned surfaces in terms of nanostructure quality or effective surface area, which is vital for applications. Further, using scaling analysis, we associate Si surfaces generated within particular angular or fluence range to different universality classes, which can help towards understanding of their formation mechanism. (paper)

  19. Disordering and annealing effects of magnesium aluminate spinel implanted with high-flux 60 keV Cu-

    Magnesium aluminate spinel of single crystal MgOn(Al2O3) was implanted with 60 keV Cu- at a flux up to 100 μA/cm2, and effects of damage accumulation on the lattice were studied by Rutherford backscattering spectrometry (RBS)/channeling measurements. No complete amorphization was observed in the spinel over the flux range examined in this study, although the crystalline lattice was significantly damaged. The damaged region on the Al sublattice extended to a deeper region with increasing flux. Fluence- and flux dependence of Al damage peak is greatly influenced by the stoichiometry n of spinel. The Al damage peak of MgO1.0(Al2O3) is smaller for higher flux and fluence. It is understood that recombination of radiation-induced interstitials with structural vacancies effectively reduces damage of the Al sublattice. In the case of MgO2.4(Al2O3), the Al damage peak, however, increases with increasing fluence and flux. The results of RBS/channeling indicate that the recombination mechanism is more effective in the stoichiometric spinel than the nonstoichiometric one

  20. Disordering and annealing effects of magnesium aluminate spinel implanted with high-flux 60 keV Cu{sup -}

    Lee, C.G. E-mail: lee.chi.gyu@nims.go.jp; Takeda, Y.; Kishimoto, N

    2002-05-01

    Magnesium aluminate spinel of single crystal MgOn(Al{sub 2}O{sub 3}) was implanted with 60 keV Cu{sup -} at a flux up to 100 {mu}A/cm{sup 2}, and effects of damage accumulation on the lattice were studied by Rutherford backscattering spectrometry (RBS)/channeling measurements. No complete amorphization was observed in the spinel over the flux range examined in this study, although the crystalline lattice was significantly damaged. The damaged region on the Al sublattice extended to a deeper region with increasing flux. Fluence- and flux dependence of Al damage peak is greatly influenced by the stoichiometry n of spinel. The Al damage peak of MgO1.0(Al{sub 2}O{sub 3}) is smaller for higher flux and fluence. It is understood that recombination of radiation-induced interstitials with structural vacancies effectively reduces damage of the Al sublattice. In the case of MgO2.4(Al{sub 2}O{sub 3}), the Al damage peak, however, increases with increasing fluence and flux. The results of RBS/channeling indicate that the recombination mechanism is more effective in the stoichiometric spinel than the nonstoichiometric one.

  1. Ion-induced photon emission of magnesium aluminate spinel during 60 keV Cu{sup -} implantation

    Bandourko, V.; Lay, T.T.; Takeda, Y.; Lee, C.G.; Kishimoto, N. E-mail: kishin@nrim.go.jp

    2001-04-01

    The beam-solid interaction during high flux heavy-ion implantation has been studied by the in situ detection of photon emission. A spinel of MgO{center_dot}n(Al{sub 2}O{sub 3}) with n=2.4 was irradiated with 60 keV Cu{sup -} at dose rates of 10, 50 or 100 {mu}A/cm{sup 2} to a dose of 1.5x10{sup 17} ions/cm{sup 2}. Under the implantation, photon emission ranging from 1.4 to 6.2 eV was detected by a time-resolved optical device based on a fast-response CCD (Princeton Instruments: IMAX-512). Emission lines of sputtered Mg, Al and Cu atoms were observed. A comparison of the dose and dose rate dependence of the Cu I line intensity from MgO{center_dot}n(Al{sub 2}O{sub 3}) with those obtained for amorphous (a-)SiO{sub 2} substrate revealed the good correlation of Cu I line intensity with nanoparticle formation detected by optical absorbance measurement.

  2. Disordering and annealing effects of magnesium aluminate spinel implanted with high-flux 60 keV Cu -

    Lee, C. G.; Takeda, Y.; Kishimoto, N.

    2002-05-01

    Magnesium aluminate spinel of single crystal MgO n(Al 2O 3) was implanted with 60 keV Cu - at a flux up to 100 μA/cm 2, and effects of damage accumulation on the lattice were studied by Rutherford backscattering spectrometry (RBS)/channeling measurements. No complete amorphization was observed in the spinel over the flux range examined in this study, although the crystalline lattice was significantly damaged. The damaged region on the Al sublattice extended to a deeper region with increasing flux. Fluence- and flux dependence of Al damage peak is greatly influenced by the stoichiometry n of spinel. The Al damage peak of MgO1.0(Al 2O 3) is smaller for higher flux and fluence. It is understood that recombination of radiation-induced interstitials with structural vacancies effectively reduces damage of the Al sublattice. In the case of MgO2.4(Al 2O 3), the Al damage peak, however, increases with increasing fluence and flux. The results of RBS/channeling indicate that the recombination mechanism is more effective in the stoichiometric spinel than the nonstoichiometric one.

  3. Defect creation by 10-keV electron irradiation in phosphorous-doped a-Si:H

    Changes in gap state distribution due to defects induced by different doses of 10-keV electrons in phosphorous-doped a-Si:H are reported. These defects have been observed qualitatively by electron beam writing. Patterns thus generated were read by electron beam induced current (EBIC). The increased local recombination in the area results in the decrease of EBIC current due to the increased defect density. Shift in the Fermi level position after electron irradiation was observed from the measurement of conductivity with temperature. Deep level transient spectroscopy (DLTS) was used to study the changes in gap states for the different electron dose. It was observed that irradiation causes the generation of additional defects which alter the gap state distribution in the n-type material over a broad range of energies. Creation of defects having activation energies around 0.55 eV below the conduction band was prominent although the formation of dangling bonds which results in increase in states around 0.7 eV is observed. These defects act as nonradiative recombination centers as suggested from the photoluminescence results which show a decrease in the 0.85 photoluminescence peak intensity. The contrast produced in the electron beam writing could be annealed out at 150 degree C, indicating the metastability of the defects, which was also confirmed by the DLTS, photoluminescence, and dark conductivity measurements

  4. TEC evidence for near-equatorial energy deposition by 30-keV electrons in the topside ionosphere

    Suvorova, A V; Tsai, L -C; Kunitsyn, V E; Andreeva, E S; Nesterov, I A; Lazutin, L L

    2013-01-01

    Observations of energetic electrons (10 - 300 keV) by NOAA/POES and DMSP satellites at heights <1000 km during the period from 1999 to 2010 allowed finding abnormal intense fluxes of ~10^6 - 10^7 cm-2 s-1 sr-1 for quasi-trapped electrons appearing within the forbidden zone of low latitudes over the African, Indo-China, and Pacific regions. Extreme fluxes appeared often in the early morning and persisted for several hours during the maximum and recovery phase of geomagnetic storms. We analyzed nine storm-time events when extreme electron fluxes first appeared in the Eastern Hemisphere, then drifted further eastward toward the South-Atlantic Anomaly. Using the electron spectra, we estimated the possible ionization effect produced by quasi-trapped electrons in the topside ionosphere. The estimated ionization was found to be large enough to satisfy observed storm-time increases in the ionospheric total electron content determined for the same spatial and temporal ranges from global ionospheric maps. Additional...

  5. Structural changes of surfaces of spacecraft solar array protective glasses being irradiated by 20-keV electrons

    Khasanshin, R. H.; Novikov, L. S.

    2016-05-01

    When irradiating K-208 and CMG glasses by 20-keV electrons with flux densities of 1010 < φe < 2 × 1011 cm-2 s-1 in vacuum 10-4 Pa, electrostatic discharges accompanied by plasma emission and destruction of glass surfaces were observed. Examination of glasses by atomic force microscopy (AFM) showed significant difference in structural changes of surfaces of K-208 and CMG samples irradiated by equal flux densities within the range from 2.0 × 1010 to 9.0 × 1010 cm-2 s-1 that can be explained by different mechanisms of removal of charge accumulated in glasses. Surface discharges generating channels on surfaces of K-208 and CMG glasses appear when φ ⩾ 7.4 × 1010 cm-2 s-1 and φ ⩾ 8.7 × 1010 cm-2 s-1 respectively. In average, if radiation conditions are the same and φ ⩾ 1.4 × 1011 cm-2 s-1, the channels are 1.5 times deeper in K-208 than in CMG.

  6. Small-angle coherent gamma-ray scattering at 662 keV for Pb and Sn

    Discrepancies between theory and experiment have been reported in the small-momentum-transfer region x -1 for the coherent scattering of moderate-energy photons. In the present experiment an investigation has been made of the performance of each of the primary components of an annular target setup, arranged for 662 keV photon scattering at angles in the range 50-150. The conventional double-cone primary-beam stop is found to significantly degrade the full-energy peak-to-valley ratio compared to that obtained with a parallel-sided arrangement. Asymmetry has been found in the response of the detector to an auxiliary point source radially distributed over the scattering plane. Appropriate experimental procedures and corrections have been adopted in obtaining differential cross sections of reduced uncertainty. Results obtained on the basis of present measurements are found to be in accordance with theory. A reanalysis of an earlier set of experimentally determined differential cross sections has been produced. (author)

  7. High-Power Electron Landau-Heating Experiments in the Lower Hybrid Frequency Range in a Tokamak Plasma

    Porkolab, M.; Lloyd, B.; Takase, Y.; Bonoli, P.; Fiore, C.; Gandy, R.; Granetz, R.; Griffin, D.; Gwinn, D.; Lipschultz, B.; Marmar, E.; McCool, S.; Pachtman, A.; Pappas, D.; Parker, R.; Pribyl, P.; Rice, J.; Terry, J.; Texter, S.; Watterson, R.; Wolfe, S.

    1984-09-01

    The effectiveness of plasma heating by electron Landau interaction in the lower hybrid range of frequencies in tokamak plasmas is demonstrated. Upon injection of 850 kW of rf power at a density of n―e~=1.4×1014 cm-3, an electron temperature increase of 1.0 keV and an ion temperature increase of 0.8 keV was achieved. These results are compared with transport and ray-tracing code predictions.

  8. The average 0.5-200 keV spectrum of local active galactic nuclei and a new determination of the 2-10 keV luminosity function at z \\approx 0

    Ballantyne, D R

    2013-01-01

    The broadband X-ray spectra of AGNs contains information about the nuclear environment from Schwarzschild radii scales to distances of ~1 pc. In addition, the average shape of the X-ray spectrum is an important input into X-ray background synthesis models. Here, local (z \\approx 0) AGN luminosity functions (LFs) in five energy bands are used as a low-resolution, luminosity-dependent X-ray spectrometer in order to constrain the average AGN X-ray spectrum between 0.5 and 200 keV. The 15-55 keV LF measured by Swift-BAT is assumed to be the best determination of the local LF, and then a spectral model is varied to determine the best fit to the 0.5-2 keV, 2-10 keV, 3-20 keV and 14-195 keV LFs. The spectral model consists of a Gaussian distribution of power-laws with a mean photon-index and cutoff energy E_cut, as well as contributions from distant and disc reflection. The reflection strength is parameterised by varying the Fe abundance relative to solar, A_Fe, and requiring a specific Fe K equivalent width (EW). ...

  9. Towards measurements of recoils below 4 keV with the 'ROSEBUD' experiment

    An experiment to look for light WIMPs with sapphire bolometers is to be installed in the Canfranc Underground Laboratory (at 2450 m.w.e) in the Spanish Pyrenees. In the first stage two small 25g bolometers with NTD-Ge sensors, operating at 25 mK, with an energy threshold of 300eV and FWHM energy resolution of 120eV at 1.5keV will perform a background test experiment. The features of the bolometers, the radioactivity measurements of the components and the set-up and status of the experiment are reported

  10. Dissociative ionization cross sections of CO2 at electron impact energy of 5 keV

    The dissociative ionization of CO2 induced by 5 keV electrons in two-body and three-body dissociative channels of CO22+ and CO23+ is identified by the ion—ion coincidence- method using a momentum imaging spectrometer. The partial ionization cross sections (PICSs) of different ionic fragments are measured and the results generally agree with the calculations made by a semi-empirical approach. Furthermore, the PICSs of the dissociative channels are also obtained by carefully considering the detection efficiency of the micro-channel plates and the total transmission efficiency of the time of flight system. (atomic and molecular physics)

  11. Design of water-cooling system for 750 keV radio frequency quadrupole injector

    The cooling design of a 201.25 MHz, 750 keV radio frequency quadrupole injector is described in this paper. The essential parameters for the design of the cooling pipes are obtained from the RF structure design. The hydrodynamics and thermal characteristics are theoretically analyzed. Computer simulation is performed using the steady state thermal analysis module of the radio-frequency software. Numerical computation shows that the increase of temperature is controlled within 1 K, the accelerator can work steadily with this cooling system. The cooling design satisfies the physical requirement very well. (authors)

  12. Beam emittance reconstructions at the KFUPM 350 keV ion accelerator

    We successfully reconstructed the horizontal and vertical beam emittances of a 160 keV low-intensity deuteron ion beam from the Energy Research Laboratory's low intensity duoplasmatron deuteron ion source. Reconstructions were made from horizontal and vertical beam width measurements. These measurements were done using only one quadrupole triplet and a beam profile monitor situated towards the end of the 45 beam line of the 350 kV ion accelerator. The deuteron beam emittances were εh = 67 π mm-mrad and εv = 4π mm-mrad at 90% of the beam. (orig.)

  13. Gaseous Detector with sub keV Threshold to Study Neutrino Scattering at Low Recoil Energies

    Kopylov, A V; Petukhov, V V; Solomatin, A E

    2014-01-01

    Gaseous detector with a sub keV electron equivalent threshold is a very perspective tool for the precision measurement of the neutrino magnetic moment and to observe coherent scattering of neutrinos on nuclei. The progress in the development of low noise electronics makes it possible to register the rare events at the threshold less than 100 eV. The construction of the gaseous detector is given and the typical pulses with amplitudes of a few eV observed on a bench scale installation are presented. The possible implications for future experiments are discussed.

  14. Sublinear effect in light emission from cesium iodide bombarded by keV polyatomic projectiles

    Baudin, K.; Parilis, E. S.; Blankenship, J. F.; Van Stipdonk, M. J.; Schweikert, E. A.

    1998-02-01

    Our experiments examined light emission from a CsI target bombarded with polyatomic projectiles [H n+, (NaF) nNa +, with n=1,2; Na +, Cs 2I +, Cs +] at 5-30 keV impact energies. The light emission increases with primary ion velocity as ( V - Vth) α, where Vth is a velocity threshold. The number of photons emitted under one cluster impact increases with the number of atoms in the projectile, displaying a sublinear effect, similar to that reported elsewhere for electron emission. The model of sweeping out electrons has been applied to explain and calculate the observed effect.

  15. Field ion microscopy of defects in tungsten caused by 140 keV proton irradiation

    The disturbances in the crystal structure of tungsten during its bombardment with 140 KeV protons (the integral dose of irradiation is 2.1016 protons/cm2, the specimens were irradiated out of the microscope at a room temperature) with the auto-ionic helium microscope operating at 78 deg K were investigated. The random pinpoint defects and small pores in the irradiated specimens were observed. The reasons for discrepancy between the estimated concentration of single displaced atoms and the concentration determined by reference to the autonomous images of the irradiated specimens are discussed

  16. L-shell ionization of Sn and Gd by 20 - 100 keV electron impact

    Measurements have been made of the relative x-ray production cross section Lsub(α)/Lsub(γ), Lsub(α)/Lsub(β) and Lsub(α)/Lsub(l) using electrons of energy 20 to 100 keV incident on thin targets of tin and gadolinium. The experimental ratios obtained have been compared with theoretical values. Modification of these ratios due to the formation of double vacancy atomic states has been calculated, but this effect on its own is not sufficient to account for the discrepancy between theory and experimental results

  17. Microchannel plate pinhole camera for 20 to 100 keV x-ray imaging

    We present the design and construction of a sensitive pinhole camera for imaging suprathermal x-rays. Our device is a pinhole camera consisting of four filtered pinholes and microchannel plate electron multiplier for x-ray detection and signal amplification. We report successful imaging of 20, 45, 70, and 100 keV x-ray emissions from the fusion targets at our Novette laser facility. Such imaging reveals features of the transport of hot electrons and provides views deep inside the target

  18. Wettability characteristic of PTFE and glass surface irradiated by keV ions

    Commercial PTFE and soda lime glass were irradiated by keV O3+ and F4+. After irradiation, in contrast to the decrease of contact angle on PTFE, contact angle on glass increased apparently. SEM observation revealed that irradiation did not cause noticeable change in surface topological structure. XPS was used to investigate chemical structure changes on the surface. Defluorination effect and formation of oxygen containing group caused by irradiation were considered to the reason of more hydrophilic PTFE surface. On the surface of irradiated glass, more carbon contaminations were observed. The differences of underlying physical and chemical processes between the two kinds of samples are discussed

  19. Observing E0-transition in 160Dy with energy K703.38 KeV

    Full text: We continue to study the E0-transitions and 0+-states in 160Dy [1]. The photo plates were irradiated in magnetic spectrographs in JINR [2]. To search internal conversion of electron (ICE) lines from Er and Ho fractions we used MAS-1 set up in ITEP [3]. We found lines with electron energy of 649.59 keV near famous ICE lines K707.6 keV. Intensity of that line is 1/3 of the K707.6 line. Analysis of the γ-transitions in 160Dy [4] pointed on absence of the lines of other isotopes in that γ-spectra. As a result, we suggest that found K703.38 line is E0 transition, which connect 0+ ground state with new 0+ excited level with energy of 703.38 keV in 160Dy. Earlier, we reported [1] about excited level with energy of 681.3 keV close to the level found now. It is reasonable to note, that in theoretical investigations it is of interest to discover existence of '0+-twins' in even-even nuclei in rare-earth area [5]. The IVBM calculations [6] for 160Dy nucleons inside pointed on existence of such levels. New investigations of (e,e'p) reactions on 12C gave 20% effect of nucleons combination with opposite spins [7]. Such calculations for heavy nuclei, show that 25% paired nucleons exist inside nuclei [8]. And it is serious support of IVBM. References: 1. Adam, et al. // Book of Abstracts 57 International Conference on Nuclear Physics NUCLEUS 2007. June 25-29. 2007. Voronezh. Russia. P. 106.; 2. A.A. Abdurazakov et al. // Constant magnet beta-spectrographs. Tashkent FAN 1972.; 3. O.K. Egorov et al. // JTP. 2003. v.73, ed. 3, p.96 (JTF. 2003. V.48. No 3).; 4. J. Adam et al. // Izv. RAN. ser. Fiz. 2002. V.66. P.1384, and C.W. Reich. // Nuclear Data Sheets. 2005.105. 557; 5. S.K. Abdulvagabova, G. Schultz // JINR. P4-7750. Dubna. 1974.; 6. A.A. Solnyshkin et al. // Phys. Rev. C. 2005. V.72. P.064321-1.; 7. R. Subedi et al. // Science. 2008. V. 320. P. 1475; 8. D. Higinbotham, E. Piasetzky and M. Strikman // CERN Courier 2009. N 1. P. 22 (authors)

  20. Attenuation coefficients of 123 keV γ-radiation by dilute solutions of sodium chloride

    The linear attenuation and mass attenuation (or absorption) coefficients of the 123 keV γ radiation from 57Co by dilute solutions of NaCl were studied for varying concentrations. The mixture rule for the theoretical calculation of attenuation coefficients was developed for solutions. This study explores the validity of the expected exponential attenuation absorption law for γ-radiation in solutions and also provides an alternative method for the direct determination of linear and mass attenuation coefficients of soluble salts in solid form without obtaining them in pure crystalline form. (Author)

  1. Kinetic energy releases of small amino acids upon interaction with keV ions

    In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation of the gas-phase amino acids glycine, alanine and valine upon interaction with keV α-particles. High resolution coincidence time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies. (authors)

  2. Kuosimalliston suunnittelu Finlaysonille : freelancerina sesonkiin kevät/kesä 2016

    Karaiste, Pauliina

    2015-01-01

    Opinnäytetyön aiheena on kuosimalliston suunnittelu Finlaysonille freelancerina sesonkiin kevät/kesä 2016. Opinnäytetyö on työelämälähtöinen, sillä tekijä on tekstiilimuotoilun opintojensa aikana keskittynyt kuosisuunnitteluun ja myynyt Niityllä-kuosin Finlaysonille. Tekijällä on aiempaa kokemusta kuosisuunnittelusta myös Carlsonille. Tekijä työskentelee freelancer-kuosisuunnittelijan roolissa ja tutkii freelancerin työnkuvaa tavoitteenaan freelancer- kuosisuunnittelijana työskentely muot...

  3. Lifetime of the 563-keV level of 24Na

    The lifetime of the 563 KeV level of 24Na has been measured by means of the recoil-distance method. In the geometry used, the ''stopped'' and ''shifted'' peaks lie above and below the K edge of bismuth. The use of a bismuth absorber of suitable thickness essentially eliminated the stopped peak from the spectrum, leading to an exponential function for the transmitted intensity as a function of the recoil distance. The mean life was measured as tau/subm/ = 62 plus-or-minus 8 ps

  4. Search of a cyclotron line at 70 keV from Crab Nebula

    An observation of Crab Nebula was made during a transmediterranean balloon flight launched on August 26, 1979 from Milo Base. The hard x-ray experiment carried a payload consisting of two multiwire proportional counters having a geometric area of 900 cm2 each. A single transit scan of the source was performed on the Crab Nebula region at a float altitude of 2.9 mbs. The preliminary results indicate the existence of an excess flux between 64 - 76 keV above the expected value of Esup(-2.0) power law

  5. Kinetic energy releases of small amino acids upon interaction with keV ions

    Bari, S.; Alvarado, F.; Postma, J.; Sobocinski, P.; Hoekstra, R.; Schlatholter, T. [Groningen Univ., KVI Atomic Physics (Netherlands); Schlatholter, T. [Universites P. et M. Curie and D. Diderot, INSP, CNRS UMR 75-88, 75 - Paris (France)

    2009-01-15

    In chromatin, DNA is tightly packed into one complex together with histone and non-histone proteins. These proteins are known to protect the DNA against indirect and to some extent even direct radiation damage. Radiation action upon amino acids is thus one of the primary steps in biological radiation action. In this paper we investigate the ionization and fragmentation of the gas-phase amino acids glycine, alanine and valine upon interaction with keV {alpha}-particles. High resolution coincidence time-of-flight mass spectrometry is used to determine the dominant fragmentation channels as well as fragment kinetic energies. (authors)

  6. Biological effect of 20 keV N+ ion implantation on Stevia rebaudianum

    The germinability and gemination rate of Stevia rebaudianum seeds implanted with 20 keV N+ ions in doses of 0 (CK), 100 x 2500, 400 x 2500 and 1000 x 2500 N+/cm2 were studied by analyzing the differences in seed germinability and gemination rate between the groups. By statistical analysis, the germinability and gemination rate were affected at the level of α=0.05 by the implantation dose. The results showed that the germinability and gemination rate increased with the dose first and then decreased. At 400 x 2500 N+/cm2, the seeds had the largest germinability and the gemination rate. (authors)

  7. Search for parity violation in the 1081 keV γ-transition of 18F

    The effect of a parity violation in the atomic nucleus by neutral currents can be studied on 18F. The theory predicts a circular polarization of the 1081 KeV γ transition of about 5per mille. In the framework of this thesis an improved poalrimeter for the measurement of the γ circular polarization was constructed. Furthermore an apparature containing 4 Ge(Li) detectors was extended by 4 NaI detectors. The circular polarization was determined to (-1.0 +- 1.8)per mille. (orig.)

  8. Subsurface and interface channeling of keV ions in graphene/SiC

    Rosandi, Yudi, E-mail: rosandi@physik.uni-kl.de [Fachbereich Physik und Forschungszentrum OPTIMAS, Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany); Department of Physics, Universitas Padjadjaran, Jatinangor, Sumedang 45363 (Indonesia); Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.de [Fachbereich Physik und Forschungszentrum OPTIMAS, Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany)

    2014-12-01

    Using molecular-dynamics simulation, we study the impact of 3 keV Ar and Xe ions on a β-SiC (1 1 1) surface covered by a single graphene layer. At glancing ion incidence angles, we observe the ions to undergo interface channeling between the graphene and the first SiC surface layer. This behavior is particularly pronounced for Xe ions, where at incidence angles of 70–75° more than 50% of the ions are channeled. This process is accompanied by abundant damage production and sputtering in the graphene layer. Similarities and differences to subsurface channeling in elemental materials are discussed.

  9. Attenuation coefficient of 123 keV gamma radiation by dilute solution of ferrous sulphate

    Linear and mass attenuation coefficients of 123 keV gamma radiation from Co57 by dilute solutions of FeSO4.7H2O salt are studied for varying concentrations. The mixture rule for theoretical calculation of attenuation coefficients is developed for solutions. The study explores the validity of the expected exponential attenuation absorption law for gamma radiation in solutions and also provides alternative method for direct determination of linear and mass attenuation coefficients of soluble salts in solid form without obtaining them in pure crystalline form. (author). 12 refs., 1 tab., 1 fig

  10. Improved energies for the 5.2 keV M1 and 42.0 keV M2 nuclear transitions in {sup 83}Rb

    Inoyatov, A.Kh. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); National University, Institute of Applied Physics, Tashkent (Uzbekistan); Rysavy, M. [Nuclear Physics Institute of the ASCR, Rez (Czech Republic); Kovalik, A. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Nuclear Physics Institute of the ASCR, Rez (Czech Republic); Filosofov, D.V.; Yushkevich, Yu.V. [JINR, Laboratory of Nuclear Problems, Dubna (Russian Federation); Zhdanov, V.S. [Nuclear Physics Institute, Almaty (Kazakhstan)

    2014-03-15

    The low-energy electron spectrum following the decay of {sup 83}Sr was analysed at high instrumental resolution by an electrostatic spectrometer. Significantly improved energies of 5235.7 ± 0.8 and 42078.0 ± 1.8 eV were determined from the conversion electron spectra for the nuclear transitions depopulating the first 3/2{sup -} and the second 9/2{sup +} excited states in {sup 83}Rb to the 5/2{sup -} ground state, respectively. The M1 character for the 5.2 keV nuclear transition was confirmed and the E2 admixture parameter δ{sup 2}(E2/M1) = (2.6 ± 0.2) x 10{sup -5} was obtained. Values of 2.8 ± 0.2, 3.8 ± 0.2, 1.4 ± 0.3, 1.4 ± 0.4, and 4.1 ± 0.3 eV were determined for the K, L{sub 1}, L{sub 2}, L{sub 3}, and M{sub 1} natural atomic level widths of rubidium, respectively. (orig.)

  11. SPI/INTEGRAL observation of 1809 keV gamma-ray line emission from the Cygnus X region

    Knödlseder, J; Allain, M M; Boggs, S; Diehl, R; Jean, P; Kretschmer, K; Roques, J P; Schönfelder, V; Vedrenne, G; Von Ballmoos, P; Weidenspointner, G; Winkler, C

    2004-01-01

    We present first results on the observation of 1809 keV gamma-ray line emission from the Cygnus X region with the SPI imaging spectrometer. Our analysis is based on data from the performance verification phase of the INTEGRAL instruments and comprises 1.3 Ms of exposure time. We observe a 1809 keV line flux of (7.3 +/- 0.9) x 10-5 ph cm-2 s-1 from a region delimited by galactic longitudes 73-93 deg and |b| < 7 deg at a significance level of 8 sigma. The 1809 keV line appears moderately broadened, with an intrinsic FWHM of 3.3 +/- 1.3 keV. Although this broadening is only marginal (at the 2 sigma level our data are compatible with an unbroadened line), it could reflect the 26Al ejecta kinematics.

  12. Development of a compact focused gaseous ion beam system with a maximum energy of 300 keV

    A compact focused gaseous ion beam system with a maximum energy of 300 keV is developed at Japan Atomic Energy Agency (JAEA). The compact system was designed so as to be installed in an ordinary experiment room. The system consists of a double acceleration lens and an acceleration tube. The double acceleration lens system was developed to form gaseous ion nanobeams with energy of several tens of keV previously at JAEA. In this study, the acceleration tube was newly developed as the third acceleration lens on the basis of calculation to optimize lens parameters; such as magnification, aberrations and focusing point. The beam size at the focusing point of the acceleration tube is expected to be 130 nm in diameter at energy of 300 keV on the basis of the previous study of the keV gaseous ion nanobeam forming by the double acceleration lens system. (author)

  13. Hard X-ray photoelectron spectroscopy (HAXPES) (15 keV) at SpLine, the Spanish CRG beamline at the ESRF

    In this contribution we present the actual status of the SpLine project devoted to the implementation of hard (15 keV) X-ray photoelectron spectroscopy (HAXPES) in combination with surface X-ray diffraction (SXRD) at the Spanish CRG beamline (SpLine) at the European Synchrotron Radiation Facility (ESRF). The beamline is located at the bending magnet D25 at the ESRF and can be operated in the X-ray energy range 5-45 keV. The main project goals are the detection of very high kinetic energy photoelectrons up to 15 keV, in particular the simultaneous detection of the diffracted photons and photo-emitted electrons. Therefore, special effort has been devoted to develop a novel electron analyzer, capable of working at very high as well as low energies. The analyzer is a sector of a Cylindrical Mirror Analyzer (CSA300HV) with a five-elements retarding-lens system and a very compact size compared to standard hemispherical analyzers. Additionally, an ultra-high-vacuum system has been constructed which will simultaneously fulfill the requirements for HAXPES and SXRD. The vacuum chamber has two Be windows so that the in-coming and out-going X-ray beam will hit the sample and the X-ray detector, respectively. The complete system will be installed on a massive 2S+3D diffractometer. Photoelectron spectroscopy and SXRD can be operated either simultaneously or independently from each other. Test experiments with a UV discharge lamp and a RHEED electron gun have been conducted demonstrating that the analyzer performs satisfactorily. The whole set-up is in the commissioning phase and full operation is expected in the course of 2005

  14. PET attenuation coefficients from CT images: experimental evaluation of the transformation of CT into PET 511-keV attenuation coefficients

    The CT data acquired in combined PET/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the range of 40-140 keV must be transformed into linear attenuation coefficients at the PET energy of 511 keV. As attenuation depends on photon energy and the absorbing material, an accurate theoretical relation cannot be devised. The transformation implemented in the Discovery LS PET/CT scanner (GE Medical Systems, Milwaukee, Wis.) uses a bilinear function based on the attenuation of water and cortical bone at the CT and PET energies. The purpose of this study was to compare this transformation with experimental CT values and corresponding PET attenuation coefficients. In 14 patients, quantitative PET attenuation maps were calculated from germanium-68 transmission scans, and resolution-matched CT images were generated. A total of 114 volumes of interest were defined and the average PET attenuation coefficients and CT values measured. From the CT values the predicted PET attenuation coefficients were calculated using the bilinear transformation. When the transformation was based on the narrow-beam attenuation coefficient of water at 511 keV (0.096 cm-1), the predicted attenuation coefficients were higher in soft tissue than the measured values. This bias was reduced by replacing 0.096 cm-1 in the transformation by the linear attenuation coefficient of 0.093 cm-1 obtained from germanium-68 transmission scans. An analysis of the corrected emission activities shows that the resulting transformation is essentially equivalent to the transmission-based attenuation correction for human tissue. For non-human material, however, it may assign inaccurate attenuation coefficients which will also affect the correction in neighbouring tissue. (orig.)

  15. Extension of self-seeding scheme with single crystal monochromator to lower energy < 5 keV as a way to generate multi-TW scale pulses at the European XFEL

    Geloni, Gianluca; Saldin, Evgeni

    2012-01-01

    We propose a use of the self-seeding scheme with single crystal monochromator to produce high power, fully-coherent pulses for applications at a dedicated bio-imaging beamline at the European X-ray FEL in the photon energy range between 3.5 keV and 5 keV. We exploit the C(111) Bragg reflection (pi-polarization) in diamond crystals with a thickness of 0.1 mm, and we show that, by tapering the 40 cells of the SASE3 type undulator the FEL power can reach up to 2 TW in the entire photon energy range. The present design assumes the use of a nominal electron bunch with charge 0.1 nC at nominal electron beam energy 17.5 GeV. The main application of the scheme proposed in this work is for single shot imaging of individual protein molecules.

  16. Telemetry Ranging: Concepts

    Hamkins, J.; Kinman, P.; Xie, H.; Vilnrotter, V.; Dolinar, S.

    2015-11-01

    Telemetry ranging is a proposed alternative to conventional two-way ranging for determining the two-way time delay between a Deep Space Station (DSS) and a spacecraft. The advantage of telemetry ranging is that the ranging signal on the uplink is not echoed to the downlink, so that telemetry alone modulates the downlink carrier. The timing information needed on the downlink, in order to determine the two-way time delay, is obtained from telemetry frames. This article describes the phase and timing estimates required for telemetry ranging, and how two-way range is calculated from these estimates. It explains why the telemetry ranging architecture does not require the spacecraft transponder to have a high-frequency or high-quality oscillator, and it describes how a telemetry ranging system can be infused in the Deep Space Network.

  17. Minnesota Pheasant Range

    Minnesota Department of Natural Resources — This dataset delineates the spatial range of wild pheasant populations in Minnesota as of 2002 by dividing the MN state boundary into 2 units: pheasant range and...

  18. High-efficiency Fresnel zone plates for hard X-rays by 100 keV e-beam lithography and electroplating

    The efficiencies of several Fresnel zone plates, that were fabricated using a direct-write method with high-energy electrons, were measured over a wide range of photon energies. The fabrication and characterization of Fresnel zone plates (FZPs) for hard X-ray microscopy applications are reported. High-quality 500 nm- and 1 µm-thick Au FZPs with outermost zone widths down to 50 nm and 70 nm, respectively, and with diameters up to 600 µm were fabricated. The diffraction efficiencies of the fabricated FZPs were measured for a wide range of X-ray energies (2.8–13.2 keV) showing excellent values up to 65–75% of the theoretical values, reflecting the good quality of the FZPs. Spatially resolved diffraction efficiency measurements indicate the uniformity of the FZPs and a defect-free structure

  19. Energy and angular distributions of backscattered electrons from collisions of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets

    R K Yadav; R Shanker

    2007-03-01

    The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between B = 50 eV and 5000 eV. The angle of incidence α and take-off angle are chosen to have values = 0° and 10° and = 100°, 110° and 120° respectively. The measured energy spectra are compared with the available theoretical models for = 0° and 10°. The elastic peak intensity of backscattered electrons is found to be a function of angle of incidence, take-off angle and atomic number of the target material. The considered theories are reasonably in good agreement with experiment for the energy spectra of the backscattered electrons having their reduced energies (= B/0) in the range of 0.20 to 1.00.

  20. High-efficiency Fresnel zone plates for hard X-rays by 100 keV e-beam lithography and electroplating

    Gorelick, Sergey, E-mail: sergey.gorelick@psi.ch; Vila-Comamala, Joan; Guzenko, Vitaliy A. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Barrett, Ray; Salomé, Murielle [European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble Cedex (France); David, Christian [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)

    2011-05-01

    The efficiencies of several Fresnel zone plates, that were fabricated using a direct-write method with high-energy electrons, were measured over a wide range of photon energies. The fabrication and characterization of Fresnel zone plates (FZPs) for hard X-ray microscopy applications are reported. High-quality 500 nm- and 1 µm-thick Au FZPs with outermost zone widths down to 50 nm and 70 nm, respectively, and with diameters up to 600 µm were fabricated. The diffraction efficiencies of the fabricated FZPs were measured for a wide range of X-ray energies (2.8–13.2 keV) showing excellent values up to 65–75% of the theoretical values, reflecting the good quality of the FZPs. Spatially resolved diffraction efficiency measurements indicate the uniformity of the FZPs and a defect-free structure.

  1. Modelling of the implantation and the annealing stages of 800 keV 3He implanted tungsten: Formation of nanovoids in the near surface region

    The formation of voids in tungsten implanted at room temperature with 800 keV 3He atoms and subsequently annealed from 300 K to 900 K is modelled using an Object Kinetic Monte Carlo code. Different fluences are investigated ranging from 1017 to 5 × 1020 ions m−2 and comparisons are made with Positron Annihilation Spectroscopy results. Good agreements with the experimental results are obtained regarding the temperature range at which the vacancy clustering occurs and the dependency of the nanovoid size with fluence. Despite the small amount of He atoms in the investigated region named “track region”, their role is underlined and it is shown that they act as nuclei for the nanovoid formation. The non trivial consequence is that the higher the fluence, the smaller the nanovoids in the track region.

  2. Origin of the 6.4-keV line of the Galactic Ridge X-ray Emission

    Tsuru, T G; Nobukawa, K K; Nobukawa, M; Nakashima, S; Koyama, K; Torii, K; Fukui, Y

    2014-01-01

    We report the first results from high-statistics observation of the 6.4-keV line in the region of $l= +1.5^\\circ$ to $+3.5^\\circ$ (hereafter referred to as GC East), with the goal to uncover the origin of the Galactic ridge X-ray emission (GRXE). By comparing this data with that from the previous observations in the region $l=-1.5^\\circ$ to $-3.5^\\circ$ (hereafter referred to as GC West), we discovered that the 6.4-keV line is asymmetrically distributed with respect to the Galactic center, whereas the 6.7-keV line is symmetrically distributed. The distribution of the 6.4-keV line follows that of $^{13}$CO and its flux is proportional to the column density of the molecular gas. This correlation agrees with that seen between the 6.4-keV line and the cold interstellar medium (ISM) (H$_{\\rm I}$ $+$ H$_2$) in the region $|l|>4^\\circ$. This result suggests that the 6.4-keV emission is diffuse fluorescence from the cold ISM not only in GC East and West but also in the entire Galactic plane. This observational result...

  3. Gain ranging amplifier

    A gain ranging amplifier system is provided for use in the acquisition of data. Voltage offset compensation is utilized to correct errors in the gain ranging amplifier system caused by thermal drift and temperature dependent voltage offsets, both of which are associated with amplifiers in the gain ranging amplifier system

  4. The positron density in the intergalactic medium and the galactic 511 keV line

    Vecchio, A; Miralda-Escude, J; Pena-Garay, C

    2013-01-01

    The 511 keV electron-positron annihilation line, most recently characterized by the INTEGRAL/SPI experiment, is highly concentrated towards the Galactic centre. Its origin remains unknown despite decades of scrutiny. We propose a novel scenario in which known extragalactic positron sources such as radio jets of active galactic nuclei (AGN) fill the intergalactic medium with MeV e+e- pairs, which are then accreted into the Milky Way. We show that interpreting the diffuse cosmic radio background (CRB) as arising from radio sources with characteristics similar to the observed cores and radio lobes in powerful AGN jets suggests that the intergalactic positron-to-electron ratio could be as high as 10^{-5}, although this can be decreased if the CRB is not all produced by pairs and if not all positrons escape to the intergalactic medium. Assuming an accretion rate of one solar mass per year of matter into the Milky Way, a positron-to-electron ratio of only 10^{-7} is already enough to account for much of the 511 keV...

  5. High power neutral beam operation at 120 keV with a single stage extraction system

    A 37 A, 120 keV, 0.1 s pulse length, perveance matched hydrogen beam has been obtained reliably by using a three electrode extraction system with shaped circular apertures illuminated by a rectangular periplasmatron ion source of 12 x 38 cm2 full extraction area. The length of the ''accel'' gap was 2 cm and the extracted ion current density, at 120 keV, J+ = 200 mA/cm2. The injector was operated with a neutralizing gas cell of nl approximately = 7.1015 mol/cm2 gas target thickness. Divergence angles as low as 0.65deg in hydrogen and 0.4deg in argon have been measured. The grid power loadings, normalized to the H.V drain power and to the ion source filling pressure (mTorr) were: 0.1% for the plasma grid, 0.02% for the negative grid and 0.07% for the neutralizer grid. The results show that such a 3-grid system is suitable for high energy injectors required for the JET device and that it can be advantageously utilized instead of a 4-grid system on account of its greater simplicity. (author)

  6. Design of optic system for 500 keV/10 mA electron beam machine

    In the 1995/1996 Research Year design of Electron Beam Machine components i.e. : Electron Source, High Voltage Supply, Accelerator Tube, Focussing System, Steering System, Scanning System, Vacuum System, Radiation Facility and Conveyer System also Electronics and Control System was carried out. This paper describes the design of Focussing, Steering and Scanning System. The Focussing System was an iron sheathed solenoid the Steering System was two sets of electromagnet placed perpendicular each other and the Scanning System was a set of alternating current electromagnet. The first Focussing System was designed to have 1 m focus distance for electron beam of 10 keV energy the second Focussing System was designed to have 1 m focus distance for electron beam of 1 MeV energy, the Steering System was designed to have 30o deflection angle for electron beam of 1 MeV energy and the Scanning System was designed to have 120 cm deflection distance and 20o deflection angle for electron beam of 1 MeV. Using these systems the 500 keV/10 mA Electron Beam Machine could be controlled. (author)

  7. The X-Ray Line Feature At 3.5 Kev In Galaxy Cluster Spectra

    Phillips, K J H; Sylwester, J

    2015-01-01

    Recent work by Bulbul et al. and Boyarsky et al. has suggested that a line feature at approx. 3.5 keV in the X-ray spectra of galaxy clusters and individual galaxies seen with XMM-Newton is due to the decay of sterile neutrinos, a dark matter candidate. This identification has been criticized by Jeltema and Profumo on the grounds that model spectra suggest that atomic transitions in helium-like potassium (K XVIII) and chlorine (Cl XVI) are more likely to be the emitters. Here it is pointed out that the K XVIII lines have been observed in numerous solar flare spectra at high spectral resolution with the RESIK crystal spectrometer and also appear in Chandra HETG spectra of the coronally active star sigma Gem. In addition, the solar flare spectra at least indicate a mean coronal potassium abundance which is a factor of between 9 and 11 higher than the solar photospheric abundance. This fact, together with the low statistical quality of the XMM-Newton spectra, completely accounts for the approx. 3.5 keV feature a...

  8. Performance improvement of keV Neutrons-based PGNAA setups

    Naqvi, A.A. [Department of Physics, King Fahd University of Petroleum and Minerals, KFUPM Box 1815, Dhahran-31261 (Saudi Arabia)]. E-mail: aanaqvi@kfupm.edu.sa; Abdelmonem, M.S. [Department of Physics, King Fahd University of Petroleum and Minerals, KFUPM Box 1815, Dhahran-31261 (Saudi Arabia); Al-Misned, Ghada [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia); Al-Ghamdi, Hanan [Girls Education College, Riyadh Girls Colleges, Riyadh (Saudi Arabia)

    2006-12-15

    The performance of keV neutrons based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setups have been observed to improve by enclosing its neutron source inside the moderator. The keV neutrons were produced via {sup 7}Li(p,n) reaction and {sup 3}H(p,n) reactions. For the two PGNAA setups, the maximum intensity of the prompt {gamma}-ray yield was observed for a 5 cm long moderator with the neutron source positioned at a distance of 0.5 cm from the moderator-end facing the sample. Due to enclosing the source inside the moderator, the prompt {gamma}-ray yield from the {sup 7}Li(p,n) reaction and {sup 3}H(p,n) reaction based PGNAA setups have increased by a factor of three as compared to that achieved from these setups with the source outside the moderator. This study provides a theoretical basis for the measurement of performance of {sup 7}Li(p,n) reaction and the {sup 3}H(p,n) reaction based PGNAA setups.

  9. Performance improvement of keV Neutrons-based PGNAA setups

    The performance of keV neutrons based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setups have been observed to improve by enclosing its neutron source inside the moderator. The keV neutrons were produced via 7Li(p,n) reaction and 3H(p,n) reactions. For the two PGNAA setups, the maximum intensity of the prompt γ-ray yield was observed for a 5 cm long moderator with the neutron source positioned at a distance of 0.5 cm from the moderator-end facing the sample. Due to enclosing the source inside the moderator, the prompt γ-ray yield from the 7Li(p,n) reaction and 3H(p,n) reaction based PGNAA setups have increased by a factor of three as compared to that achieved from these setups with the source outside the moderator. This study provides a theoretical basis for the measurement of performance of 7Li(p,n) reaction and the 3H(p,n) reaction based PGNAA setups

  10. Performance improvement of keV Neutrons-based PGNAA setups.

    Naqvi, A A; Abdelmonem, M S; Al-Misned, Ghada; Al-Ghamdi, Hanan

    2006-12-01

    The performance of keV neutrons based Prompt Gamma Ray Neutron Activation Analysis (PGNAA) setups have been observed to improve by enclosing its neutron source inside the moderator. The keV neutrons were produced via (7)Li(p,n) reaction and (3)H(p,n) reactions. For the two PGNAA setups, the maximum intensity of the prompt gamma-ray yield was observed for a 5cm long moderator with the neutron source positioned at a distance of 0.5cm from the moderator-end facing the sample. Due to enclosing the source inside the moderator, the prompt gamma-ray yield from the (7)Li(p,n) reaction and (3)H(p,n) reaction based PGNAA setups have increased by a factor of three as compared to that achieved from these setups with the source outside the moderator. This study provides a theoretical basis for the measurement of performance of (7)Li(p,n) reaction and the (3)H(p,n) reaction based PGNAA setups. PMID:16837206

  11. The 511 keV emission from positron annihilation in the Galaxy

    Prantzos, N; Bykov, A M; Diehl, R; Ferriere, K; Guessoum, N; Jean, P; Knoedlseder, J; Marcowith, A; Moskalenko, I V; Strong, A; Weidenspointner, G

    2010-01-01

    The first gamma-ray line originating from outside the solar system that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990's with OSSE/CGRO showed that the emission is strongly concentrated towards the Galactic bulge. In the 2000's, the SPI instrument aboard ESA's INTEGRAL gamma-ray observatory allowed scientists to measure that emission across the entire Galaxy, revealing that the bulge/disk luminosity ratio is larger than observed in any other wavelength. This mapping prompted a number of novel explanations, including rather "exotic ones (e.g. dark matter annihilation). However, conventional astrophysical sources, like type Ia supernovae, microquasars or X-ray binaries, are still plausible candidates for a large fraction of the observed total 511 keV emission of the bulge. A closer study of the subject reveals new...

  12. Production of Sterile Neutrino dark matter and the 3.5 keV line

    Alexander Merle

    2015-10-01

    Full Text Available The recent observation of an X-ray line at an energy of 3.5 keV mainly from galaxy clusters has initiated a discussion about whether we may have seen a possible dark matter signal. If confirmed, this signal could stem from a decaying sterile neutrino of a mass of 7.1 keV. Such a particle could make up all the dark matter, but it is not clear how it was produced in the early Universe. In this letter we show that it is possible to discriminate between different production mechanisms with present-day astronomical data. The most stringent constraint comes from the Lyman-α forest and seems to disfavor all but one of the main production mechanisms proposed in the literature, which is the production via decay of heavy scalar singlets. Pinning down the production mechanism will help to decide whether the X-ray signal indeed comprises an indirect detection of dark matter.

  13. Stimulated Raman scattering in hydrogen by ultrashort laser pulse in the keV regime

    Bachau, H.; Dondera, M.

    2016-04-01

    This letter addresses the problem of stimulated Raman excitation of a hydrogen atom submitted to an ultrashort and intense laser pulse in the keV regime. The pulse central frequency ω of 55 a.u. (about 1.5 keV) is in the weakly relativistic regime, ω ≤ c/a0 (c is the speed of light in vacuum and a 0 the Bohr radius) and the pulse duration is τ ≈ 18.85 a.u. (about 456 attoseconds). We solve the corresponding time-dependent Schrödinger equation (TDSE) using a spectral approach, retardation (or nondipole) effects are included up to O(1/c) , breaking the conservation of the magnetic quantum number m and forcing the resolution of the TDSE in a three-dimensional space. Due to the laser bandwidth, which is of the order of the ionization potential of hydrogen, stimulated Raman scattering populates nlm excited states (n and l are the principal and azimuthal quantum numbers, respectively). The populations of these excited states are calculated and analyzed in terms of l and m quantum numbers, this showing the contributions of the retardation effects and their relative importance.

  14. Radiation damage studies on STAR250 CMOS sensor at 300 keV for electron microscopy

    Faruqi, A. R.; Henderson, R.; Holmes, J.

    2006-09-01

    There is a pressing need for better electronic detectors to replace film for recording high-resolution images using electron cryomicroscopy. Our previous work has shown that direct electron detection in CMOS sensors is promising in terms of resolution and efficiency at 120 keV [A.R. Faruqi, R. Henderson, M. Prydderch, R. Turchetta, P. Allport, A. Evans, Nucl. Instr. and Meth. 546 (2005) 170], but in addition, the detectors must not be damaged by the electron irradiation. We now present new measurements on the radiation tolerance of a 25 μm pitch CMOS active-pixel sensor, the STAR250, which was designed by FillFactory using radiation-hard technology for space applications. Our tests on the STAR250 aimed to establish the imaging performance at 300 keV following irradiation. The residual contrast, measured on shadow images of a 300 mesh grid, was >80% after corrections for increased dark current, following irradiation with up to 5×10 7 electrons/pixel (equivalent to 80,000 electron/μm 2). A CMOS sensor with this degree of radiation tolerance would survive a year of normal usage for low-dose electron cryomicroscopy, which is a very useful advance.

  15. Hydroxyapatite-titanium interface reaction induced by keV electron irradiation

    Torrisi, L.; Foti, G.

    1992-03-01

    Thin films of hydroxyapatite bioceramic, 5-50 Å in thickness, have been deposited on ion cleaned titanium surfaces to study the chemical-physical adhesion of metal-ceramic interfaces of biomedical devices (orthopaedic and dentistry prosthesis). Film deposition was performed in ultrahigh vacuum condition (10 -10 mbar) using 5 keV argon sputtering of hydroxyapatite matrix; the film thickness was measured in situ with Auger electron spectroscopy. The hydroxyapatite-titanium interface was irradiated with an electron beam of 0.5-5 keV energy and 0.2-2 A/cm 2 current density. During electron irradiation, Auger spectra show chemical shifts of phosphorus, titanium and oxygen peaks. The released electron energy induces modifications in the tetraedric phosphorus-oxygen groups with production of new chemical bonds between phosphorus, oxygen and titanium. Oxygen, for example, diffuses into the titanium interface forming titanium oxide. Chemical reactions induced by electron irradiation are driven by the metal-ceramic interface. Near the interface a strong and fast effect is observed while far from the interface a weak and slow effect occurs. Chemical reactions depend on the electron irradiation dose showing an inhibition threshold at about 10 19 e/cm 2 and, near the interface, a saturation condition at about 5 × 10 20 e/cm 2. Titanium-ceramic chemical reactions are inhibited if the substrate titanium surface is rich in oxide.

  16. Sputtering of condensed rare gases by keV charged particles

    Measurements were made of the absolute total yield and ejected particle energy spectra for argon, krypton and xenon solids sputtered by 33-ke V He+, Ne+, Ar+, Kr+ and Xe+ ions, as well as energy spectra for 2.5-keV electrons incident on these solids. For the heavier incident ions (Ne-Xe), the energy spectra are combined with the measured total yields to produce total yield curves that are differential in the ejected particle energy. These absolute ejected particle energy spectra are then compared to the predictions of the standard collision cascade theory of sputtering, providing a much more critical test of the model than when the total yield and energy spectra are compared with the theory separately. The ejected particle energy spectra for these solids bombarded by keV electrons and He+ ions provide detailed information about the sputtering mechanism for electronically excited rare gas solids. The observation of clear peaks in the energy spectra of these targets at higher ejection energies reveals that repulsive decays of a very definite energy are a major contributor to the electronic sputtering mechanism. The widths and positions of the peaks in all three solids are related to the measured VUV luminescence produced by the decay of excited dimers in the electronically rare gas solids

  17. Sputtering of thin benzene and polystyrene overlayers by keV Ga and C60 bombardment

    The mechanisms of ion-stimulated desorption of thin organic overlayers deposited on metal substrates by mono- and polyatomic projectiles are examined using molecular dynamics (MD) computer simulations. A monolayer of polystyrene tetramers (PS4) physisorbed on Ag{1 1 1} is irradiated by 15 keV Ga and C60 projectiles at normal incidence. The results are compared with the data obtained for a benzene overlayer to investigate the differences in sputtering mechanisms of weakly and strongly bound organic molecules. The results indicate that the sputtering yield decreases with the increase of the binding energy and the average kinetic energy of parent molecules is shifted toward higher kinetic energy. Although the total sputtering yield of organic material is larger for 15 keV C60, the impact of this projectile leads to a significant fragmentation of ejected species. As a result, the yield of the intact molecules is comparable for C60 and Ga projectiles. Our data indicate that chemical analysis of the very thin organic films performed by detection of sputtered neutrals will not benefit from the use of C60 projectiles

  18. Uranium Enrichment Measurements without Calibration Using Gamma Rays Above 100 keV

    Ruhter, W D; Wang, T F; Hayden, C

    2001-09-27

    The verification of UF{sub 6} shipping cylinders is an important activity in routine safeguards inspections. Current measurement methods using either sodium-iodide or high-purity germanium detectors require calibrations that are not always appropriate for field measurements, because of changes in geometry or container wall thickness. The introduction of the MGAU code demonstrated the usefulness of intrinsically calibrated measurements for inspections. MGAU uses the 100-keV region of the uranium gamma-ray spectrum. The thick walls of UF{sub 6} shipping cylinders and the low-energy analysis preclude the routine use of MGAU for these measurements. We have developed a uranium enrichment measurement method for measurements using high-purity germanium detectors, which do not require calibration, and uranium gamma rays above 100 keV. The method uses seven gamma rays from {sup 235}U and {sup 238}U to determine their relative detection efficiency intrinsically and with an additional gamma ray from {sup 234}U, the relative abundance of these three uranium isotopes. The method uses a function that describes the basic physical processes that predominantly determine the relative detection efficiency curve. These are the detector efficiency, the absorption by the cylinder wall, and the self-absorption by the uranium contents. We will describe this model and initial testing on various uranium materials and detector types.

  19. Hitomi constraints on the 3.5 keV line in the Perseus galaxy cluster

    Aharonian, Felix A; Akimoto, Fumie; Allen, Steven W; Angelini, Lorella; Arnaud, Keith A; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W; Blandford, Roger D; Brenneman, Laura W; Brown, Gregory V; Bulbul, Esra; Cackett, Edward M; Chernyakova, Maria; Chiao, Meng P; Coppi, Paolo; Costantini, Elisa; de Plaa, Jelle; Herder, Jan-Willem den; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C; Ferrigno, Carlo; Foster, Adam R; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko; Hornschemeier, Ann E; Hoshino, Akio; Hughes, John P; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Shota; Inoue, Yoshiyuki; Ishibashi, Kazunori; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Itoh, Masayuki; Iyomoto, Naoko; Kaastra, Jelle S; Kallman, Timothy; Kamae, Tuneyoshi; Kara, Erin; Kataoka, Jun; Katsuda, Satoru; Katsuta, Junichiro; Kawaharada, Madoka; Kawai, Nobuyuki; Kelley, Richard L; Khangulyan, Dmitry; Kilbourne, Caroline A; King, Ashley L; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Shu; Koyama, Katsuji; Kretschmar, Peter; Krimm, Hans A; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lebrun, Francois; Lee, Shiu-Hang; Leutenegger, Maurice; Limousin, Olivier; Loewenstein, Michael; Long, Knox S; Lumb, David; Madejski, Grzegorz M; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R; Mehdipour, Missagh; Miller, Eric D; Miller, Jon M; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Moseley, Harvey; Mukai, Koji; Murakami, Hiroshi; Murakami, Toshio; Mushotzky, Richard F; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakano, Toshio; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko; Nobukawa, Masayoshi; Noda, Hirofumi; Nomachi, Masaharu; O'Dell, Steve L; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stephane; Parmar, Arvind; Petre, Robert; Pinto, Ciro; Pohl, Martin; Porter, F Scott; Pottschmidt, Katja; Ramsey, Brian D; Reynolds, Christopher S; Russell, Helen R; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sameshima, Hiroaki; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemitsos, Peter J; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K; Soong, Yang; Stawarz, Lukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew E; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shin'ichiro; Takei, Yoh; Tamagawa, Toru; Tamura, Keisuke; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki; Tashiro, Makoto; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Ueno, Shiro; Uno, Shin'ichiro; Urry, C Meg; Ursino, Eugenio; de Vries, Cor P; Watanabe, Shin; Werner, Norbert; Wik, Daniel R; Wilkins, Dan R; Williams, Brian J; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Yoshida, Atsumasa; Zhuravleva, Irina; Zoghbi, Abderahmen

    2016-01-01

    High-resolution X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified E=3.5 keV emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported flux level. The high flux derived with XMM MOS for the Perseus region covered by Hitomi is excluded at >3-sigma within the energy confidence interval of the most constraining previous study. If XMM measurement uncertainties for this region are included, the inconsistency with Hitomi is at a 99% significance for a broad dark-matt...

  20. View into the cage of the 520 keV preaccelerator of the PS Linac 1

    1974-01-01

    The "open pill box" (in the background at the left) contains the ion source, where for many years all protons accelerated at CERN were "born". It is directly attached to the acceleration column where the protons pass from 520 kV to earth potential. The "electronics platform" (big metal structure on insulating pillars in the middle of the picture, for details see 7403120 and 7403071X) contains all the equipment that has to be at the same potential as the source itself. The smaller metal box in the foreground is part of the "bouncer", which compensated the voltage drop during acceleration of a proton pulse. The high voltage generator (not included in this photo)was originally a Cockcroft-Walton column. In 1973 it was replaced by a Sames generator (see 7403074X). Visible at the bottom right of the picture is the conductor from the "Sames". The "old" 50 MeV Linac 1, the original PS injector built in the 1950s, was (since 1976) replaced by a new 50 keV linac (Linac 2). It had a 750 keV "Cockcroft-Walton" pre-injec...

  1. Development of a collimated keV X-ray beam for probing of dense plasmas

    Experimental findings of a fully optical, keV x-ray source of 1-2 degrees divergence and broadband spectrum (> 5 keV bandwidth) are presented. The radiation results from the highly relativistic interaction of a 30 TW (1 J, 30 fs) laser pulse through a 3 mm length span of He gas (ne = 1*1019 electrons/cm3). Quantitative measurements from the filtered back-illuminated CCD give 105 protons/eV, and the knife-edge technique measures the source diameter of 10 μm. These source characteristics, the measured beam of relativistic electrons, and PIC (particle-in-cell) simulation indicate the radiation results from forceful transverse oscillations of the laser-accelerated electrons in response to the ionic channel formed by the laser pulse. The source brightness (107 photons/eV/mm2/mr2/shot and ultra-fast duration (≤ 30 fs) make it applicable to both back-lighting and X-ray science applications. (authors)

  2. Estimation of keV submicron ion beam width using a knife-edge method

    Ishii, Yasuyuki; Isoya, Akira; Kojima, Takuji; Arakawa, Kazuo

    2003-11-01

    A beam width measurement system has been developed for keV submicron ion beams of 0.1 μm or less in width assuming a round shape beam. The system enables to measure beam current change as a function of knife-edge position by cutting a beam focusing point (beam spot) with the sharp edge within a spatial resolution of 0.02 μm. The width of 30 keV order submicron H + ion beam was estimated by fitting current change curves based on three different ion density models: uniform, flat-top and Gaussian. Among these models, the flat-top model provide the most reasonable beam width of 0.56 μm interpreting contribution of halo around the beam spot to beam width estimation. The beam width measurement system with the high spatial resolution and the data analysis based on the flat-top ion density model should contribute to accelerate developments of submicron ion beam production technologies.

  3. Estimation of keV submicron ion beam width using a knife-edge method

    A beam width measurement system has been developed for keV submicron ion beams of 0.1 μm or less in width assuming a round shape beam. The system enables to measure beam current change as a function of knife-edge position by cutting a beam focusing point (beam spot) with the sharp edge within a spatial resolution of 0.02 μm. The width of 30 keV order submicron H+ ion beam was estimated by fitting current change curves based on three different ion density models: uniform, flat-top and Gaussian. Among these models, the flat-top model provide the most reasonable beam width of 0.56 μm interpreting contribution of halo around the beam spot to beam width estimation. The beam width measurement system with the high spatial resolution and the data analysis based on the flat-top ion density model should contribute to accelerate developments of submicron ion beam production technologies

  4. Telemetry Ranging: Signal Processing

    Hamkins, J.; Kinman, P.; Xie, H.; Vilnrotter, V.; Dolinar, S.

    2016-02-01

    This article describes the details of the signal processing used in a telemetry ranging system in which timing information is extracted from the downlink telemetry signal in order to compute spacecraft range. A previous article describes telemetry ranging concepts and architecture, which are a slight variation of a scheme published earlier. As in that earlier work, the telemetry ranging concept eliminates the need for a dedicated downlink ranging signal to communicate the necessary timing information. The present article describes the operation and performance of the major receiver functions on the spacecraft and the ground --- many of which are standard tracking loops already in use in JPL's flight and ground radios --- and how they can be used to provide the relevant information for making a range measurement. It also describes the implementation of these functions in software, and performance of an end-to-end software simulation of the telemetry ranging system.

  5. Telemetry-Based Ranging

    Hamkins, Jon; Vilnrotter, Victor A.; Andrews, Kenneth S.; Shambayati, Shervin

    2011-01-01

    A telemetry-based ranging scheme was developed in which the downlink ranging signal is eliminated, and the range is computed directly from the downlink telemetry signal. This is the first Deep Space Network (DSN) ranging technology that does not require the spacecraft to transmit a separate ranging signal. By contrast, the evolutionary ranging techniques used over the years by NASA missions, including sequential ranging (transmission of a sequence of sinusoids) and PN-ranging (transmission of a pseudo-noise sequence) whether regenerative (spacecraft acquires, then regenerates and retransmits a noise-free ranging signal) or transparent (spacecraft feeds the noisy demodulated uplink ranging signal into the downlink phase modulator) relied on spacecraft power and bandwidth to transmit an explicit ranging signal. The state of the art in ranging is described in an emerging CCSDS (Consultative Committee for Space Data Systems) standard, in which a pseudo-noise (PN) sequence is transmitted from the ground to the spacecraft, acquired onboard, and the PN sequence is coherently retransmitted back to the ground, where a delay measurement is made between the uplink and downlink signals. In this work, the telemetry signal is aligned with the uplink PN code epoch. The ground station computes the delay between the uplink signal transmission and the received downlink telemetry. Such a computation is feasible because symbol synchronizability is already an integral part of the telemetry design. Under existing technology, the telemetry signal cannot be used for ranging because its arrival-time information is not coherent with any Earth reference signal. By introducing this coherence, and performing joint telemetry detection and arrival-time estimation on the ground, a high-rate telemetry signal can provide all the precision necessary for spacecraft ranging.

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

    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

  7. Time-of-flight mass spectrometry with desorption-ionization multiprobes (UV photons and KeV and MeV particles). Cluster atoms are used as projectiles

    A new time-of-flight mass spectrometer, Super-Depil, is used to study secondary ion emission from solid surfaces bombarded by various kinds of primary particles. Three different desorption probes were set up on this machine: a 252 californium source, providing by spontaneous fission about 1 MeV/u energy heavy ions, a 5 to 30 keV energy pulsed caesium ion gun and a pulsed nitrogen laser, which wavelength is 337 mm. A two stages electrostatic mirror was added to the spectrometer. The time spread due to the initial kinetic energy of secondary ions leaving the surface was minimized. The mass resolution is greater than 5000. The analysis of glycosidic terpenes showed the complementarity of the three probes. The study of such metastable ions, with the electrostatic mirror, showed that some fragment ions may conserve the memory of the stereochemistry of the neutral lost. Clusters ions were used as projectiles in the energy range 5-60 keV. A strong non linear enhancement was observed in the secondary ion yield from various targets

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

    Singh, Amrit; Dhaliwal, A. S., E-mail: dhaliwalas@hotmail.com [Department of Physics, Sant Longowal Institute of Engineering and Technology, Longowal(Sangrur) -148106, Punjab (India)

    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.

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

    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.

  10. An experimental study on cross-section ratio of coherent to incoherent scattering for 145 keV incident gamma photons

    The coherent (Rayleigh) to incoherent (Compton) scattering cross-section ratio of elements, in the range 6 ≤ Z ≤ 82, are determined experimentally for 145 keV incident gamma photons. An HPGe (High purity germanium) semiconductor detector is employed, at scattering angle of 50°, 70° and 90°, to record the spectra originating from interactions of incident gamma photons with the target under investigation. The intensity ratio of Rayleigh to Compton scattered peaks observed in the recorded spectra, and corrected for photo-peak efficiency of gamma detector and absorption of photons in the target and air, along with the other required parameters provides the differential cross-section ratio. The measured values of cross-section ratio are found to agree with theoretical predictions (corresponding to 4.939, 6.704 and 8.264 Å−1 photon momentum transfer) based upon non-relativistic form factor, relativistic form factor, modified form factor and S-matrix theory. -- Highlights: • Measurements of Rayleigh to Compton cross-section ratio for 145 keV photons. • Prior to this, no data are available at this energy for any scattering angles. • Intensity ratio of Rayleigh to Compton peaks provides the cross-section ratio. • Measured values of cross-section ratio agree with various theoretical predictions. • Source activity, solid angles subtended by source and detector at target are not required

  11. High-resolution measurement of the 238U neutron capture yield for incident neutron energies between 1 and 100 keV

    The capture cross section of 238U in the energy range up to 100 keV is one of the important nuclear parameters in reactor design. Nevertheless, the uncertainties in this parameter are still above reactor design requirements. These uncertainties, which were discussed at the Antwerp Conference on Nuclear Data (Sept. 1982), led to the formation of the 238U task force of the Nuclear Energy Agency Nuclear Data Committee (NEANDC). Among the most relevant conclusions arrived at by the NEANDC task force were that, since most of the capture cross-section measurements were old and disagreed among themselves by more than expected from their respective error assignment, a new high-resolution measurement was needed and the resolved resonance energy region should be extended above its present 4-keV limit. In response to these requests, a measurement of the 238U capture yield was performed at the 150-m flight-path station of the Oak Ridge Electron Linear Accelerator (ORELA) facility. The energy resolution achieved in this measurement frequently resulted in spectacular doublet and triplet splittings of what appeared to be single resonances in previous measurements. The present 238U capture yield measurements has provided a wealth of data that, when combined with recent transmission results, will have a significant impact in both reactor design and neutron spectroscopy studies

  12. Dark matter inelastic up-scattering with the interstellar plasma: A new source of x-ray lines, including at 3.5 keV

    D'Eramo, Francesco; Hambleton, Kevin; Profumo, Stefano; Stefaniak, Tim

    2016-05-01

    We explore the phenomenology of a class of models where the dark matter particle can inelastically up-scatter to a heavier excited state via off-diagonal dipolar interactions with the interstellar plasma (gas or free electrons). The heavier particle then rapidly decays back to the dark matter particle plus a quasimonochromatic photon. For the process to occur at appreciable rates, the mass splitting between the heavier state and the dark matter must be comparable to, or smaller than, the kinetic energy of particles in the plasma. As a result, the predicted photon line falls in the soft x-ray range, or, potentially, at arbitrarily lower energies. We explore experimental constraints from cosmology and particle physics, and present accurate calculations of the dark matter thermal relic density and of the flux of monochromatic x rays from thermal plasma excitation. We find that the model provides a natural explanation for the observed 3.5 keV line from clusters of galaxies and from the Galactic center, and is consistent with null detections of the line from dwarf galaxies. The unique line shape, which will be resolved by future observations with the Hitomi (formerly Astro-H) satellite, and the predicted unique morphology and target-temperature dependence will enable easy discrimination of this class of models versus other scenarios for the generation of the 3.5 keV line or of any other unidentified line across the electromagnetic spectrum.

  13. Dark Matter Search Using Chandra Observations of Willman 1, and a Spectral Feature Consistent with a Decay Line of a 5 keV Sterile Neutrino

    Loewenstein, Michael

    2009-01-01

    We report the results of a search for an emission line from radiatively decaying dark matter in the Chandra X-ray Observatory spectrum of the ultra-faint dwarf spheroidal galaxy Willman 1. 99% confidence line flux upper limits over the 0.4-7 keV Chandra bandpass are derived and mapped to an allowed region in the sterile neutrino mass-mixing angle plane that is consistent with recent constraints from Suzaku X-ray Observatory and Chandra observations of the Ursa Minor and Draco dwarf spheroidals. A significant excess to the continuum, detected by fitting the particle-background-subtracted source spectrum, indicates the presence of a narrow emission feature with energy 2.51 +/- 0.07 (0.11) keV and flux [3.53 +/- 1.95 (2.77)] X 10^(-6) photons/cm^2/s at 68% (90%) confidence. Interpreting this as an emission line from sterile neutrino radiative decay, we derive the corresponding allowed range of sterile neutrino mass and mixing angle using two approaches. The first assumes that dark matter is solely composed of st...

  14. Laser Range Sensors

    K.C. Bahuguna

    2007-11-01

    Full Text Available This paper presents the design aspects of laser range finders and proximity sensors being developed at IRDE for different applications. The principle used in most of the laser range finders is pulse echo or time-of-flight measurement. Optical triangulation is used in proximity sensors while techniques like phase detection and interferometry are employed in instruments for surveying and motion controllers where high accuracy is desired. Most of the laser range finders are designed for ranging non-cooperative targets.

  15. Evaluations of the 253U/238U Isotope Ratio through Thick-Walled Containers using the 185.7 keV and 1001.0 keV Gamma Rays

    Lanier, R G; Hayden, C F; Clark, D; Parker, W E

    2001-04-13

    The non-destructive determination of isotope ratios (NDA) present in plutonium- and uranium-bearing materials is best accomplished with a MultiGroup Analysis methodology on spectral data obtained with high-resolution germanium detector systems. This methodology is currently employed in codes such as MGA, MGAU or U235. The MGA code, for example, works well on Pu samples and employs a number of isolated spectral lines in the analysis. The algorithm uses Gaussian and Lorentzian peak shapes that are empirically modified to account for various physical and instrumental effects. Additional effects due to external absorbers, sample self-attenuation and detector relative efficiency are also included. Uranium samples are analyzed with MGAU and U235 using a simpler but similar algorithm in the narrow energy range between 85- and 100-keV. Although the details can be complex, the problem described above is ultimately reduced to evaluating a simple ratio. Applied to uranium, for example, one evaluates where the subscripts A and B refer to quantities associated with {sup 235}U and {sup 238}U, respectively. Specifically, N{sub 235U}/N{sub 238U} is the isotope ratio {sup 235}U/{sup 238}U, I is the measured gamma-ray peak intensity, and E is the counting efficiency, BR is the appropriate branching ratio, t is the appropriate half-life, {alpha}{sup Ab} is an external absorber correction (such as cadmium, iron, etc.) and {beta}{sup U} is a correction for sample self absorption. Indications of other isotopes can, of course, be determined from different ratios evaluated with data from other characteristic gamma rays that may be present in the spectrum.

  16. Using the X-pinch x-ray source to Cross Calibrate new X-ray films with DEF from 1 - 10 keV

    Shelkovenko, T. A.; Chandler, K. M.; Pikuz, S. A.; Mitchell, M. D.; Hammer, D. A.; Knauer, J.; Meyerhofer, D.; Carpenter, B.

    2004-11-01

    Due to the recent cessation of the production of DEF x-ray film, cross calibration with other films has become necessary in order to find a replacement for DEF. DEF is sensitive over a large energy range, 2 - 35 keV, with peak sensitivity in the range of 2.5 - 5 keV, and is used in many applications. Cross calibration tests were carried out for the following Kodak films: BiomaxMR, BiomaxXAR, M100, Technical Pan, and T-Max and the same development procedures as described by Henke et al.^2 were followed for all films in every test. Various wire materials were used for the X pinches, including Al, Cu, Mo, Ni, Pd, and Ti, to span the desired x-ray energy range. In each test, a convex mica spectrograph and a Focusing Spectrometer with Spatial Resolution in 1D (FSSR-1D) with a spherically bent mica crystal were used with two pieces of 35 mm film that were cut in half. One half piece of DEF and one half piece of one of the aforementioned films were placed in each of the spectrometers so that both films were exposed by the same x-ray fluence and spectrum in every case. The same spectrum was recorded on both films in each spectrometer so that a direct comparison of the spectral sensitivities is possible. The results of these cross-calibrations will be presented and discussed. This research was supported largely by the SSAA program of the NNSA under DOE Cooperative agreement DE-FC03-02NA00057 with Cornell University. ^2Henke, et. al, "High-energy x-ray response of photographic films: models and measurement" J.Opt.Soc.AmB Vol.3, No.11, Nov 1986.

  17. Mass Absorption Coefficients At 661,6 keV Energy In Various Samples

    Determination mass absorption coefficients (mum) at 661.6 keV energy in the samples various, such as lysine, coffee, chocolate, nutrisari, coconut oil, monosodium glutamate (MSG), tea, tin fish and the soil with experiment method has been carried out. The mum research was carried out in effort to give the measurement result of Cs-137 concentration that more accurate to the samples, because the sample density increases, mass absorption coefficients (mum) decreases. The mum correction on measurement of Cs-137 concentration in the samples various around between 0 and 13%, the highest is on the chocolate sample and the lowest is on the tin fish sample. Density of the samples decreases, the mum influence increases on the counting of Cs-137 concentration in the sample (Bq/kg)

  18. Absolute Transition Probabilities from the 453.1 keV Level in 183W

    The half life of the 453.1 keV level in 183W has been measured by the delayed coincidence method to 18.4 ± 0.5 nsec. This determines twelve absolute M1 and E2 transition probabilities, out of which nine are K-forbidden. All transition probabilities are compared with the single particle estimate. The three K-allowed E2, ΔK = 2 transition rates to the 1/2- (510) rotational band are furthermore compared with the Nilsson model. An attempt to give a quantitative explanation of the observed transition rates has been made by including the effects from admixtures into the single particle wave functions

  19. 24-MW neutral-beam injector of 400-keV H0

    The negative and positive ion systems have both common goals and common problems. In fact, we have identified five items that must be developed before any large, neutral-beam injector, operating continuously or almost so, can be engineered. The five items are: (1) a continuous or almost continuous ion source, with 1A designating a source of positive ions and 1B a direct extraction source of negatives, (2) a recirculating metal-vapor cell, (3) a computer code with which to calculate beam trajectories in three dimensions, (4) a resistive coating to bleed stray charges from the surface of high-voltage vacuum insulators, and (5) an arc suppression technique for large systems. These items are discussed and it is shown how their development is prerequisite to the design of a 24-MW, 400-keV neutral hydrogen injector such as might be required for a fusion power reactor

  20. Breeding of citric acid-producing bacteria by 15 keV N+ ion implantation

    Aspergillus niger strains CK1-16, the bacteria commonly used in industrial production of citric acid, were implanted with 3.10 x 1014 to 2.58 x 1015 ions/cm2 of 15 keV N+ ions. Survival rate of the bacteria at different doses was investigated, and mutagenic effects of the microbe were studied. From the ion-implanted specimens, authors were able to obtain three mutant strains that produce increased yield of citric acid. The 71 hours yield of Mutant Strain 4 hash-8-1 incubated in cassava and corn flour media is 14% higher than the CK1-16 strain, while Mutant Strains 4hash-8-7and 4hash-8-7, incubated in corn flour media are 15.9% and 17.0% higher than the CK1-16 strain, respectively. The results also show that the mutant strains have high genetic stability. (authors)