WorldWideScience

Sample records for 5-100 kev range

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

    DEFF Research Database (Denmark)

    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....

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

    DEFF Research Database (Denmark)

    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...

  3. High resolution spectrometer for extended x-ray absorption fine structure measurements in the 6 keV to 15 keV energy range

    Science.gov (United States)

    Seely, J. F.; Hudson, L. T.; Henins, Albert; Feldman, U.

    2016-11-01

    A Cauchois transmission-crystal spectrometer has been developed with high crystal resolving power in the 6 keV-15 keV energy range and sufficient sensitivity to record single-shot spectra from the Lawrence Livermore National Laboratory (LLNL) Titan laser and other comparable or more energetic lasers. The spectrometer capabilities were tested by recording the W L transitions from a laboratory source and the extended x-ray absorption fine structure (EXAFS) spectrum through a Cu foil.

  4. Measurement of the differential neutron-deuteron scattering cross section in the energy range from 100 keV to 600 keV using a proportional counter

    CERN Document Server

    Nolte, R; Plompen, A; Röttger, S

    2014-01-01

    The angular distribution of neutron-deuteron scattering was investigated using the proportional counter P2 simultaneously as scattering target and detector for the recoil deuterons. The measurements were carried out using monoenergetic neutrons in the energy range from 150 keV to 500 keV. Various techniques were employed to reduce distortions of the experimental pulse-height distribution by photon-induced events. The experimental data were compared with realistic simulations which were carried out using different evaluated data sets. This comparison allows to conclude on inconsistencies in the evaluations.

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

    Energy Technology Data Exchange (ETDEWEB)

    Derrien, H.

    2002-09-30

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

  6. Calibration of semiconductor detectors in the 200-8500 keV range at VNIIM.

    Science.gov (United States)

    Tereshchenko, Evgeny E; Moiseev, Nikolay

    2012-09-01

    At the ionising radiation department of the D.I. Mendeleyev Institute for Metrology, a semiconductor detector was calibrated in the energy range 200-8500 keV using (n,2γ) and (n,γ) reactions. Separate cylindrical targets (77 mm diameter and 10mm height) were made from mercuric sulphate, sodium chloride and metallic titanium. A (252)Cf spontaneous fission neutron source, placed in 150 mm diameter polyethylene ball, was used to generate thermal neutrons. The optimal target dimensions were determined taking into account the thermal neutron cross-sections and gamma-radiation attenuations in the target materials. The influence of the background radiation induced by neutrons from the walls, floors and ceilings was also taken into account. The shapes of the efficiency curves for point and volume sources in the 200-8500 keV range have been investigated. The experimental results are in good agreement with Monte-Carlo calculations. The emission rate of the 6.13 MeV photons from a (238)Pu-(13)C source was determined with an expanded uncertainty, U(c), of 10% (k=2).

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

    Energy Technology Data Exchange (ETDEWEB)

    Troussel, Ph., E-mail: philippe.troussel@cea.fr [CEA, DAM, DIF, F-91297 Arpajon (France); Dennetiere, D. [Synchrotron Soleil, L’orme des Merisiers, 91190 Saint-Aubin (France); Maroni, R. [CEA, DAM, DIF, F-91297 Arpajon (France); Høghøj, P.; Hedacq, S. [Xenocs SA, 19, rue François Blumet, F-38360 Sassenage (France); Cibik, L.; Krumrey, M. [Physikalisch-Technische Bundesanstalt (PTB), Abbestr. 2-12, 10587 Berlin (Germany)

    2014-12-11

    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.

  8. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Cluster effect on projected range of 30 keV C{sub 60}{sup +} in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Y.; Nakajima, K.; Suzuki, M. [Department of Micro Engineering, Kyoto University, Kyoto 606-8501 (Japan); Narumi, K.; Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gumma 370-1292 (Japan); Vandervorst, W. [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Kimura, K., E-mail: kimura@kues.kyoto-u.ac.jp [Department of Micro Engineering, Kyoto University, Kyoto 606-8501 (Japan)

    2011-10-01

    Pre-amorphized silicon wafers are implanted with 30 keV C{sub 60}{sup +} and 0.5 keV C{sup +} ions at room temperature with fluences about 2 x 10{sup 15} atoms/cm{sup 2}. The depth profiles of implanted carbon are measured using high-resolution Rutherford backscattering spectroscopy. The observed average depth of C for the C{sub 60}{sup +} implantation is 6.1 nm while that for the C{sup +} implantation is 4.0 nm, showing a large cluster effect on the projected range.

  11. A comparative study of inelastic scattering models at energy levels ranging from 0.5 keV to 10 keV

    Science.gov (United States)

    Hu, Chia-Yu; Lin, Chun-Hung

    2017-03-01

    Six models, including a single-scattering model, four hybrid models, and one dielectric function model, were evaluated using Monte Carlo simulations for aluminum and copper at incident beam energies ranging from 0.5 keV to 10 keV. The inelastic mean free path, mean energy loss per unit path length, and backscattering coefficients obtained by these models are compared and discussed to understand the merits of the various models. ANOVA (analysis of variance) statistical models were used to quantify the effects of inelastic cross section and energy loss models on the basis of the simulated results deviation from the experimental data for the inelastic mean free path, the mean energy loss per unit path length, and the backscattering coefficient, as well as their correlations. This work in this study is believed to be the first application of ANOVA models towards evaluating inelastic electron beam scattering models. This approach is an improvement over the traditional approach which involves only visual estimation of the difference between the experimental data and simulated results. The data suggests that the optimization of the effective electron number per atom, binding energy, and cut-off energy of an inelastic model for different materials at different beam energies is more important than the selection of inelastic models for Monte Carlo electron scattering simulation. During the simulations, parameters in the equations should be tuned according to different materials for different beam energies rather than merely employing default parameters for an arbitrary material. Energy loss models and cross-section formulas are not the main factors influencing energy loss. Comparison of the deviation of the simulated results from the experimental data shows a significant correlation (p secondary electrons for backscattering coefficient simulation is recommended for elements with high atomic numbers. In hybrid models, introducing the inner shell ionization model improves the

  12. A comparative study of inelastic scattering models at energy levels ranging from 0.5 keV to 10 keV

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Chia-Yu [Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan (China); Lin, Chun-Hung, E-mail: chlin@mail.ncku.edu.tw [Department of Photonics, National Cheng Kung University, Tainan 701, Taiwan (China); Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan 701, Taiwan (China)

    2017-03-01

    Six models, including a single-scattering model, four hybrid models, and one dielectric function model, were evaluated using Monte Carlo simulations for aluminum and copper at incident beam energies ranging from 0.5 keV to 10 keV. The inelastic mean free path, mean energy loss per unit path length, and backscattering coefficients obtained by these models are compared and discussed to understand the merits of the various models. ANOVA (analysis of variance) statistical models were used to quantify the effects of inelastic cross section and energy loss models on the basis of the simulated results deviation from the experimental data for the inelastic mean free path, the mean energy loss per unit path length, and the backscattering coefficient, as well as their correlations. This work in this study is believed to be the first application of ANOVA models towards evaluating inelastic electron beam scattering models. This approach is an improvement over the traditional approach which involves only visual estimation of the difference between the experimental data and simulated results. The data suggests that the optimization of the effective electron number per atom, binding energy, and cut-off energy of an inelastic model for different materials at different beam energies is more important than the selection of inelastic models for Monte Carlo electron scattering simulation. During the simulations, parameters in the equations should be tuned according to different materials for different beam energies rather than merely employing default parameters for an arbitrary material. Energy loss models and cross-section formulas are not the main factors influencing energy loss. Comparison of the deviation of the simulated results from the experimental data shows a significant correlation (p < 0.05) between the backscattering coefficient and energy loss per unit path length. The inclusion of backscattering electrons generated by both primary and secondary electrons for

  13. New electron source concept for single-shot sub-100 fs electron diffraction in the 100 keV range

    CERN Document Server

    van Oudheusden, T; Siwick, B J; Van der Geer, S B; Root, W P E M O; Luiten, O J

    2007-01-01

    We present a method for producing sub-100 fs electron bunches that are suitable for single-shot ultrafast electron diffraction experiments in the 100 keV energy range. A combination of analytical results and state-of-the-art numerical simulations show that it is possible to create 100 keV, 0.1 pC, 20 fs electron bunches with a spotsize smaller than 500 micron and a transverse coherence length of 3 nm, using established technologies in a table-top set-up. The system operates in the space-charge dominated regime to produce energy-correlated bunches that are recompressed by established radio-frequency techniques. With this approach we overcome the Coulomb expansion of the bunch, providing an entirely new ultrafast electron diffraction source concept.

  14. SIMBOL-X, a new generation X-ray telescope for the 0.5-70 keV range

    CERN Document Server

    Ferrando, P

    2002-01-01

    SIMBOL-X is a high energy "mini" satellite class mission that is proposed by a French-Italian-English collaboration for a launch in 2009. SIMBOL-X is making use of a classical X-ray mirror, of ~ 600 cm2 maximum effective area, with a 30 m focal length in order to cover energies up to several tens of keV. This focal length will be achieved through the use of two spacecrafts in a formation flying configuration. This will give to SIMBOL-X unprecedented spatial resolution (20" HEW) and sensitivity in the hard X-ray range. By its coverage, from 0.5 to 70 keV, and sensitivity, SIMBOL-X will be an excellent instrument for the study of high energy processes in a large number of sources, as in particular accreting black-holes, extragalactic jets and AGNs.

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

    DEFF Research Database (Denmark)

    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 agrees...

  16. Gamma ray interaction studies of organic nonlinear optical materials in the energy range 122 keV-1330 keV

    Science.gov (United States)

    Awasarmol, V. V.; Gaikwad, D. K.; Raut, S. D.; Pawar, P. P.

    The mass attenuation coefficients (μm) for organic nonlinear optical materials measured at 122-1330 keV photon energies were investigated on the basis of mixture rule and compared with obtained values of WinXCOM program. It is observed that there is a good agreement between theoretical and experimental values of the samples. All samples were irradiated with six radioactive sources such as 57Co, 133Ba, 22Na, 137Cs, 54Mn and 60Co using transmission arrangement. Effective atomic and electron numbers or electron densities (Zeff and Neff), molar extinction coefficient (ε), mass energy absorption coefficient (μen/ρ) and effective atomic energy absorption cross section (σa,en) were determined experimentally and theoretically using the obtained μm values for investigated samples and graphs have been plotted. The graph shows that the variation of all samples decreases with increasing photon energy.

  17. Simultaneous solution of Kompaneets equation and Radiative Transfer equation in the photon energy range 1 - 125 KeV

    CERN Document Server

    Peraiah, A; varghese, B A

    2010-01-01

    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 is 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 $n, n^2$ and $\\displaystyle \\bigg({\\frac {\\partial n}{\\partial x_k}}\\bigg)$ where $n$ is photon phase density and $\\displaystyle x_k= \\bigg({\\frac {h \

  18. Attenuation coefficients for fibrous self-compacting concrete in the energy range of 50-3000 keV

    Energy Technology Data Exchange (ETDEWEB)

    Bento, W.V.; Magalhaes, L.A.M.; Conti, C.C., E-mail: ccconti@ird.gov.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2017-04-01

    The fibrous self-compacting concrete is a high performance concrete with uniformly distributed iron fibers. Transmission measurements, with {sup 137}Cs and {sup 60}Co sources were performed for the attenuation coefficients determination for both ordinary and fibrous self-compacting concretes. The results were compared to each other and to the values found in the literature for ordinary concrete. The mass attenuation coefficient for the fibrous self-compacting concrete showed to be higher than those for ordinary concrete of about 5%, depending on the gamma energy. However, it should be noted that the density of fibrous self-compacting concrete is higher than ordinary concrete, 2.4 g/cm{sup 3} and 1.9 g/cm{sup 3} respectively, increasing still further the difference in mass attenuation coefficient. In addition to that, by using Monte Carlo simulations, with MCNP5 Monte Carlo computer code, the data was extended to the 50-3000 keV gamma energy range. (author)

  19. Photon interaction study of organic nonlinear optical materials in the energy range 122-1330 keV

    Science.gov (United States)

    Awasarmol, Vishal V.; Gaikwad, Dhammajyot K.; Raut, Siddheshwar D.; Pawar, Pravina P.

    2017-01-01

    In the present study, the mass attenuation coefficient (μm) of six organic nonlinear optical materials has been calculated in the energy range 122-1330 keV and compared with the obtained values from the WinXCOM program. It is found that there is a good agreement between theoretical and experimental values (<3%). The linear attenuation coefficients (μ) total atomic cross section (σt, a), and total electronic cross section (σt, el) have also been calculated from the obtained μm values and their variations with photon energy have been plotted. From the present work, it is observed that the variation of obtained values of μm, μ, σt, a, and σt, el strongly depends on the photon energy and decreases or increases due to chemical composition and density of the sample. All the samples have been studied extensively using transmission method with a view to utilize the material for radiation dosimetry. Investigated samples are good material for radiation dosimetry due their low effective atomic number. The mass attenuation coefficient (μm), linear attenuation coefficients (μ), total atomic cross section (σt, a), total electronic cross section (σt, el), effective atomic numbers (Zeff), molar extinction coefficient (ε), mass energy absorption coefficient (μen/ρ) and effective atomic energy absorption cross section (σa, en) of all sample materials have been carried out and transmission curves have been plotted. The transmission curve shows that the variation of all sample materials decreases with increasing photon energy.

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

    DEFF Research Database (Denmark)

    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...

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

    Science.gov (United States)

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

    1983-04-01

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

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

    Science.gov (United States)

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

    2013-04-01

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

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

    Indian Academy of Sciences (India)

    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.

  4. Development of a soft x-ray diffractometer for a wideband multilayer grating with a novel layer structure in the 2-4 keV range

    Energy Technology Data Exchange (ETDEWEB)

    Imazono, Takashi; Koike, Masato; Kawachi, Tetsuya; Hasegawa, Noboru; Koeda, Masaru; Nagano, Tetsuya; Sasai, Hiroyuki; Oue, Yuki; Yonezawa, Zeno; Kuramoto, Satoshi; Terauchi, Masami; Takahashi, Hideyuki; Handa, Nobuo; Murano, Takanori [Quantum Beam Science Directorate, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan); Device Dept., Shimadzu Corp., 1 Nishinokyo-Kuwabara-cho, Nakagyo-ku, Kyoto 604-8511 (Japan); IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); ECBU, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan)

    2012-07-11

    We have been developing a wavelength-dispersive soft x-ray spectrograph covering an energy region of 50-4000 eV to attach to a conventional electron microscope. Observation of soft x-ray emission in the 2-4 keV range needs a multilayer coated grating. In order to evaluate the performance of the optical component in the energy region, a goniometric apparatus has been newly developed and the preliminary performance has been tested using synchrotron radiation.

  5. Development of a flat-field spectrometer with a wideband Ni/C multilayer grating in the 1–3.5 keV range

    Energy Technology Data Exchange (ETDEWEB)

    Imazono, Takashi [Quantum Beam Science Center, Japan Atomic Energy Agency, 8-1-7, Umemidai, Kizugawa, Kyoto 619-0216 (Japan)

    2016-07-27

    To develop a flat-field spectrometer with coverage of the 1–3.5 keV range, a wideband Ni/C multilayer grating was invented. The multilayer consists of two kinds of layer structures. One is a conventional periodic multilayer of thickness D{sub 1} = 5.6 nm, Ni thickness ratio to the multilayer period γ{sub 1} = 0.5 and the number of layers N{sub 1} = 79. Both the first and last layers are Ni. The other is a C/Ni bilayer of D{sub 2} = 8.4 nm, γ{sub 2} = 0.53 and N{sub 2} = 2. The first layer is C and then Ni. The aperiodic multilayer from the topmost C/Ni bilayer was coated on a laminar-type grating having an effective grating constant of 1/2400 mm, groove depth of 2.8 nm, and duty ratio (land width/groove period) of 0.5. In a preliminary experiment, the diffraction efficiency was in excess of 0.8% in the energy range of 2.1-3.3 keV and the maximum of 5.4% at 3.1 keV at a constant angle of incidence of 88.54°, which is considerably higher than that of an Au-coated grating before deposition of the multilayer.

  6. Design of a single moderator-type neutron spectrometer with enhanced energy resolution in the energy range from a few to 100 keV

    Energy Technology Data Exchange (ETDEWEB)

    Tanimura, Y. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)]. E-mail: tanimura@popsvr.tokai.jaeri.go.jp; Saegusa, J. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Yoshizawa, M. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan); Yoshida, M. [Japan Atomic Energy Research Institute, Tokai-mura, Naka-gun, Ibaraki 319-1195 (Japan)

    2005-08-01

    The moderator structure for a neutron spectrometer was optimized with the Monte Carlo code MCNP-4B. The spectrometer consists of a cylindrical moderator and a position-sensitive thermal neutron detector and obtains energy spectra from thermal neutron distribution along its cylindrical axis. The structure of the moderator was improved by using a low hydrogen density material on one end and a high hydrogen density on the other, and inserting a neutron absorber that eliminates thermal neutron diffusion. This design improves the energy resolution of the spectrometer, especially for low-energy neutrons from a few to 100 keV. The designed spectrometer can be applied to the measurement of energy spectra over a neutron energy range from a few keV to 20 MeV.

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

    Science.gov (United States)

    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. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Study of effective atomic number and electron density for tissues from human organs in the energy range of 1 keV-100 GeV.

    Science.gov (United States)

    Manjunatha, H C; Rudraswamy, B

    2013-02-01

    Effective atomic numbers' (Z(eff)) effective electron density (N(el)) for human organs and tissues have been computed in the energy region of 1 keV to 100 GeV using WinXCOM. The computed data of Z(eff) and N(el) are tabulated. The computed values are compared with previous results. The computed data of Z(eff)and N(el)for almost all tissues (34 tissues of different human organs) in the given energy range are not available in literature and find application in radiotherapy and dosimetry.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ün, Adem, E-mail: ademun25@yahoo.com; Han, İbrahim, E-mail: ibrahimhan25@hotmail.com [Ağrı İbrahim Çeçen University, Faculty of Arts and Sciences, Department of Physics, 04100 Ağrı (Turkey); Ün, Mümine, E-mail: mun@agri.edu.tr [Ağrı İbrahim Çeçen University, Vocational School, Department of Electricity and Energy, 04100 Ağrz (Turkey)

    2016-04-18

    Effective atomic (Z{sub eff}) and electron numbers (N{sub eff}) 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 Z{sub eff} and N{sub eff} 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Friedman, P.G.

    1986-11-25

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

  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

    Energy Technology Data Exchange (ETDEWEB)

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

    Science.gov (United States)

    Balsiger, H.; Eberhardt, P.; Geiss, J.; Ghielmetti, A.; Walker, H. P.; Young, D. T.; Loidl, H.; Rosenbauer, H.

    1976-01-01

    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 H-1(+) to beyond Ba-138(+) 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 focusing 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 down to flux levels of 0.01 ions/sq cm sec ster eV. A sophisticated electronics combined with powerful ground computer and telecommand systems allow for very efficient scanning of the mass-energy space.

  13. Single-crystal CVD diamond detector for low-energy charged particles with energies ranging from 100 keV to 2 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Yuki Sato; Hiroyuki Murakami [Nishina Center for Accelerator-Based Science, The Institute of Physical and Chemical Research (RIKEN), 2-1 Hirosawa, Wako, Saitama 351-0198, (Japan); Takehiro Shimaoka; Masakatsu Tsubota; Junichi, H. Kaneko [Graduate School of Engineering, Hokkaido University, N13, W8, Sapporo 060-8628, (Japan)

    2015-07-01

    The performance of a diamond detector made of a single-crystal diamond grown by chemical vapor deposition was studied for charged particles, having energies ranging from 100 keV to 2 MeV. Energy peaks of these low-energy ions were clearly observed. However, we observed that the pulse height for individual incident ion decreases with increasing atomic number of the ions. We estimated the charge collection efficiency of the generated charge carriers by charged particle incident. The charge collection above ∼95% is achieved for helium (He{sup +}) with the energy above 1.5 MeV. On the other hand, the charge collection efficiency for heavy-ions shows wrong values compared with that of He{sup +}, ∼70% for silicon (Si{sup +}) and 35 to 40% for gold (Au{sup 3+}), at the same incident energy range, respectively. (authors)

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

    DEFF Research Database (Denmark)

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

    CERN Document Server

    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.

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

    CERN Document Server

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

    Science.gov (United States)

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

    2015-12-01

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

  18. Measurement of mass attenuation coefficients of some boron compounds and the trommel sieve waste in the energy range 15.746-40.930 keV

    Energy Technology Data Exchange (ETDEWEB)

    Icelli, Orhan E-mail: orhan_icelli@hotmail.com; Erzeneoglu, Salih; Boncukcuoglu, Recep

    2003-05-01

    Mass attenuation coefficients of some boron compounds (H{sub 3}BO{sub 3}, Na{sub 2}B{sub 4}O{sub 7} and B{sub 3}Al{sub 2}O{sub 3}) and the trommel sieve waste (TSW) have been measured by using an extremely narrow collimated-beam transmission method in the energy range 15.746-40.930 keV. The characteristic K{alpha} and K{beta} X-rays of Zr, Mo, Ag, In, Sb, Ba and Pr passed through H{sub 3}BO{sub 3}, Na{sub 2}B{sub 4}O{sub 7}, B{sub 3}Al{sub 2}O{sub 3} and TSW were detected with a high-resolution Si(Li) detector. The measured values are compared with the theoretical ones obtained using the WINXCOM.

  19. Energy dependence of effective atomic numbers for photon energy absorption and photon interaction: Studies of some biological molecules in the energy range 1 keV-20 MeV

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Gerward, Leif

    2008-01-01

    Effective atomic numbers for photon energy absorption, Z(PEA,eff), and for photon interaction, Z(PI,eff), have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for biological molecules, such as fatty acids (lauric, myristic, palmitic, stearic, oleic, linoleic...... dependence of the mass attenuation coefficient, Z(PEA, eff), and the mass energy-absorption coefficient, Z(PI, eff), is shown graphically and in tabular form. Significant differences of 17%-38% between Z(PI, eff) and Z(PEA, eff) occur in the energy region 5-100 keV. The reasons for these differences...

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

    CERN Multimedia

    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...

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

    CERN Document Server

    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...

  2. Exploring pseudo-Nambu-Goldstone bosons by stimulated photon colliders in the mass range 0.1 eV to 10 keV

    Science.gov (United States)

    Homma, Kensuke; Toyota, Yuichi

    2017-06-01

    Searching for pseudo-Nambu-Goldstone bosons (pNGBs) in weak-coupling domains is crucial for understanding the dark components in the universe. We propose searching for pNGBs coupled to 2 photons in the mass range from 0.1 eV to 10 keV. This could provide opportunities to test string-theory-based pNGBs beyond the GUT scale M ˜ 10^{16} GeV included in the weak coupling proportional to M^{-1}. We provide formulae that are applicable to photon-photon scattering via a pNGB resonance exchange with a stimulation process in an asymmetric head-on photon-photon collider by mixing 3 laser pulses in laboratory experiments. We discuss the quantum electrodynamic effects on the pNGB exchange in the same mass-coupling domain as a background process from the standard model. We find that a large unexplored mass-coupling domain is accessible by combining existing laser facilities, including free-electron lasers.

  3. FIRST INTEGRAL OBSERVATIONS OF V404 CYGNI DURING THE 2015 OUTBURST: SPECTRAL BEHAVIOR IN THE 20–650 KeV ENERGY RANGE

    Energy Technology Data Exchange (ETDEWEB)

    Roques, Jean-Pierre; Jourdain, Elisabeth [Université Toulouse, UPS-OMP, CNRS, IRAP, 9 Av. Roche, BP 44346, F-31028 Toulouse (France); Bazzano, Angela; Fiocchi, Mariateresa; Natalucci, Lorenzo; Ubertini, Pietro [Istituto di Astrofisica e Planetologia Spaziali, INAF, Via Fosso del Cavaliere 100, I-00133 Roma, Italy (Italy)

    2015-11-01

    In 2015 June, the source V404 Cygni (= GS2023+38) underwent an extraordinary outburst. We present the results obtained during the first revolution dedicated to this target by the INTEGRAL mission and focus on the spectral behavior in the hard X-ray domain, using both SPI and IBIS instruments. The source exhibits extreme variability and reaches fluxes of several tens of Crab. However, the emission between 20 and 650 keV can be understood in terms of two main components, varying on all the observable timescales, similar to what is observed in the persistent black hole system Cyg X-1. The low-energy component (up to ∼200 keV) presents a rather unusual shape, probably due to the intrinsic source variability. Nonetheless, a satisfactory description is obtained with a Comptonization model, if an unusually hot population of seed photons (kT{sub 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 could correspond to the contribution of the jet synchrotron emission, as proposed in Cyg X-1. A search for an annihilation feature did not provide any firm detection, with an upper limit of 2 × 10{sup −4} ph cm{sup −2} s{sup −1} (2σ) for a narrow line centered at 511 keV, on the averaged obtained spectrum.

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

    Science.gov (United States)

    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.

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

    CERN Document Server

    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...

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

    Science.gov (United States)

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

    2015-11-01

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

  7. Total electron scattering cross sections of molecules containing H, C, N, O and F in the energy range 0.2–6.0 keV

    Energy Technology Data Exchange (ETDEWEB)

    Gurung, Meera Devi; Ariyasinghe, W.M., E-mail: wickram_ariyasinghe@baylor.edu

    2017-03-15

    Based on the effective atomic total electron scattering cross sections (EATCS) of atoms in a molecular environment, a simple model is proposed to predict the total electron scattering cross sections (TCS) of H, C, N, O, and F containing molecules. The EATCS for these five atoms are reported for 0.2–6.0 keV energies. The predicted TCS by this model are compared with experimental TCS in the literature. The experimental TCS of CHF{sub 3}, C{sub 2}F{sub 4}, C{sub 2}F{sub 2}H{sub 2}, C{sub 4}F{sub 6}, and c-C{sub 4}F{sub 8} have been obtained for 0.2–4.5 keV electrons by measuring the attenuation of the electron beam through a gas cell.

  8. Total electron scattering cross sections of molecules containing H, C, N, O and F in the energy range 0.2-6.0 keV

    Science.gov (United States)

    Gurung, Meera Devi; Ariyasinghe, W. M.

    2017-03-01

    Based on the effective atomic total electron scattering cross sections (EATCS) of atoms in a molecular environment, a simple model is proposed to predict the total electron scattering cross sections (TCS) of H, C, N, O, and F containing molecules. The EATCS for these five atoms are reported for 0.2-6.0 keV energies. The predicted TCS by this model are compared with experimental TCS in the literature. The experimental TCS of CHF3, C2F4, C2F2H2, C4F6, and c-C4F8 have been obtained for 0.2-4.5 keV electrons by measuring the attenuation of the electron beam through a gas cell.

  9. Measurement of neutron capture cross section of sup 1 sup 7 sup 4 Hf in the energy range from 162 to 1200 keV

    CERN Document Server

    Xia Yi Jun; Yang Zhi Hua

    2001-01-01

    The cross sections for the sup 1 sup 7 sup 4 Hf( n, gamma) sup 1 sup 7 sup 5 Hf reaction were measured relatively to the sup 1 sup 9 sup 7 Au(n, gamma) sup 1 sup 9 sup 8 Au reaction for neutron energies from 162 to 1200 keV, using the activation technique with high resolution HPGE gamma ray spectroscopy. Some experimental data were given for the first time

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

    Directory of Open Access Journals (Sweden)

    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.

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

    CERN Document Server

    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 ...

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  13. Study of {sup nat}Mg(d,d{sub 0}) reaction at detector angles between 90° and 170°, for the energy range E{sub d,lab}=1660–1990 keV

    Energy Technology Data Exchange (ETDEWEB)

    Patronis, N., E-mail: npatronis@uoi.gr [Department of Physics, University of Ioannina, 45110 Ioannina (Greece); Aslanoglou, X. [Department of Physics, University of Ioannina, 45110 Ioannina (Greece); Axiotis, M. [Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Georgiadou, A. [Department of Physics, University of Ioannina, 45110 Ioannina (Greece); Kokkoris, M. [Department of Physics, National Technical University of Athens, Zografou Campus, 15780 Athens (Greece); Lagoyannis, A. [Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Misaelides, P. [Department of Chemistry, Aristotle University, GR-54124 Thessaloniki (Greece); Paneta, V. [Tandem Accelerator Laboratory, Institute of Nuclear and Particle Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Department of Physics, National Technical University of Athens, Zografou Campus, 15780 Athens (Greece)

    2014-10-15

    In the present work, the study of the {sup nat}Mg(d,d{sub 0}) is presented for the energy range E{sub d,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 {sup 24}Mg(d,p{sub 0,1,2}) reaction cross section data, thus facilitating the simultaneous depth profiling study of magnesium by both the d-NRA and EBS techniques.

  14. 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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  15. 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

    Indian Academy of Sciences (India)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Electron-Impact Ionization Cross Sections of H, He, N, O, Ar, Xe, Au, Pb Atoms and Their Ions in the Electron Energy Range from the Threshold up to 200 keV

    CERN Document Server

    Povyshev, V M; Shevelko, V P; Shirkov, G D; Vasina, E G; Vatulin, V V

    2001-01-01

    Single electron-impact ionization cross sections of H, He, N, O, Ar, Xe, Au, Pb atoms and their positive ions (i.e. all ionization stages) are presented in the electron energy range from the threshold up to 200 keV. The data-set for the cross sections has been created on the basis of available experimental data and calculations performed by the computer code ATOM. Consistent data for the ionization cross sections have been fitted by seven parameters using the LSM method. The accuracy of the calculated data presented is within a factor of 2 that in many cases is sufficient to solve the plasma kinetics problems. Contributions from excitation-autoionization and resonant-ionization processes as well as ionization of atoms and ions are not considered here. The results of the numerical calculations are compared with the well-known Lotz formulae for ionization of neutral atoms and positive ions. The material is illustrated by figures and includes tables of ionization cross sections, binding energies and fitting para...

  18. Dynamical study of sup 1 H(d,gamma) sup 3 He tensor observables in the energy range of 80 kev to 95 MeV tests of effective two-body models

    CERN Document Server

    Fonseca, A C

    2000-01-01

    Realistic interactions are used to study sup 1 H(d, gamma) sup 3 He tensor observables in the energy range of 80 keV to 95 MeV deuteron laboratory energy, as well as the differential cross section for the two-body photodisintegration of sup 3 He. The Siegert form of the E1 multipole operator in the long-wavelength limit is taken as the sole component of the electromagnetic interaction. The three-body Faddeev equations for the bound-state and continuum wave functions are solved using the Paris, Argonne V14, Bonn-A, and Bonn-B potentials. The corresponding nucleon-nucleon t-matrices are represented in a separable form using the Ernst-Shakin-Thaler representation. The Coulomb force between protons is neglected and no three-nucleon force is included. The contribution of nucleon-nucleon P-wave components to the observables is carefully studied, not only in the angular distribution of the observables, but also as a function of the deuteron laboratory energy for fixed centre-of-mass angle. Comparison with data is sh...

  19. Measurement of K-X-rays fluorescence cross-sections, fluorescence yields and intensity ratios for elements in the atomic range 21 < Z < 74 excited by 59 keV photons

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Avila, J.; Lopez-Pino, N.; Padilla-Cabal, F.; Van Espen, P.; Cabal, A.; Pena, M. Ruiz; Alessandro, K.D.; Maidana, N.L. [Instituto Superior de Tecnologia y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Antwerp Univ. (Belgium). Micro Trace Analytical Center; CEADEN, La Habana (Cuba); Universidade de Sao Paulo (IF/USP), SP (Brazil). Inst. de Fisica. Lab. do Acelerador Linear

    2010-07-01

    Full text: Using 59 keV photons, we measured the K{sub {alpha}}, K{sub {beta}} and total K X-rays fluorescence cross sections of 17 elements in the atomic range 21 < Z < 74. Furthermore, the fluorescence yields and the I{sub K{beta}} / I{sub K{alpha}} intensity ratios for these elements were also determined. An annular radioactive source of {sup 241}Am (activity 1 Ci) was employed to excite the elements in targets with the shape of foils or pellets (99% purity and 20 mm, in diameter). The pellets were formed with a mixture of cellulose and a chemical compound containing the element of interest, pressed at 15 tons. The K X-rays emitted from the irradiated samples were detected by a Si(Li) detector with a frontal Pb collimator, coupled to conventional electronics, with dead time below 10%. The fluxes reaching the targets and the crystal detector were determined by means of Monte Carlo (MC) simulations using the MCNPX V 2.6 code. The input geometries included the detector, the sample-source holder and the Pb collimator. The optimal diameter for the samples as well as the collimator dimensions were estimated by means of MC simulations. Using several elements (Ti, Ni, Br, Ag, Cs, Dy and W) a calibration curve for the effective flux of photons (I{sub 0}G{sub {epsilon}}) as function of the K X-rays energy was measured. Correction by different sizes and self-absorption coefficients of the samples were also performed. The data obtained for the X-rays fluorescence cross sections were compared with semi-empirical calculations and with experimental values reported by other authors; the relative deviations were less than 10%. Keywords: fluorescence cross section, fluorescence yields, Monte Carlo (author)

  20. 41 CFR 302-5.100 - How should we administer the househunting trip expenses allowance?

    Science.gov (United States)

    2010-07-01

    ... the househunting trip expenses allowance? 302-5.100 Section 302-5.100 Public Contracts and Property...) ALLOWANCES FOR SUBSISTENCE AND TRANSPORTATION EXPENSES 5-ALLOWANCE FOR HOUSEHUNTING TRIP EXPENSES Agency Responsibilities § 302-5.100 How should we administer the househunting trip expenses allowance? You should...

  1. Sputtering of Thick Deuterium Films by KeV Electrons

    DEFF Research Database (Denmark)

    Thestrup Nielsen, Birgitte; Svendsen, Winnie Edith; Schou, Jørgen;

    1994-01-01

    Sputtering of thick films of solid deuterium up to several μm by keV electrons is reported for the first time. The sputtering yield increases within a narrow range of thicknesses around 1.6 μm by about 2 orders of magnitude for 1.5 keV electrons. A similar behavior has not been observed for ion...

  2. 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

    Institute of Scientific and Technical Information of China (English)

    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.

  3. Differential elastic and inelastic cross sections in 1. 5 <= E/sub 0/ <= 25 keV He/sup +/-H collisions at scattering angles thetasub(lab) ranging from 5' to 2/sup 0/

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, D.; Nouet, P.; Boutonnet, A.; Bergnes, C.; Dagnac, R.

    1987-09-14

    Elastic and inelastic cross sections, differential in energy loss and scattering angle, have been determined from the energy loss spectra of 1.5 - 25 keV He/sup +/ scattered from atomic hydrogen at scattering angles from 5'-2/sup 0/ (laboratory frame). The experimental results compare favourably with the experimental and theoretical data obtained at low incident energies by other authors, but for the higher energies, the present results exhibit a strong disagreement with many of the reported calculations.

  4. High-efficiency B₄C/Mo₂C alternate multilayer grating for monochromators in the photon energy range from 0.7 to 3.4 keV.

    Science.gov (United States)

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

    2014-04-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  6. Theoretical study of water adsorption and dissociation on Ta3N5(100) surfaces.

    Science.gov (United States)

    Wang, Jiajia; Luo, Wenjun; Feng, Jianyong; Zhang, Li; Li, Zhaosheng; Zou, Zhigang

    2013-10-14

    Water adsorption and dissociation on the perfect, oxygen containing and nitrogen vacancy containing Ta3N5(100) surfaces are systematically studied by density functional theory calculations. The results show that the perfect Ta3N5(100) surface is very active for water dissociation because of the dangling bonds formed on the perfect Ta3N5(100) surface. The presence of oxygen on the surface is able to stabilize the Ta3N5(100) surface but not to facilitate water dissociation, which may be ascribed to the saturation of surface dangling bonds by oxygen. The presence of a nitrogen vacancy on the surface is able to facilitate water dissociation, but Ta3N5(100) surfaces with nitrogen vacancies are not stable. We found that keeping the impurity oxygen as less as possible is one effective approach to enhance the water splitting ability of Ta3N5. We propose that doping with foreign elements is one potential method to obtain a clean Ta3N5(100) surface, since the oxygen concentration may be adjusted by competition between oxygen and foreign elements.

  7. Neutron-induced fission cross-section measurement of 234U with quasi-monoenergetic beams in the keV and MeV range using micromegas detectors

    Science.gov (United States)

    Tsinganis, A.; Kokkoris, M.; Vlastou, R.; Kalamara, A.; Stamatopoulos, A.; Kanellakopoulos, A.; Lagoyannis, A.; Axiotis, M.

    2017-09-01

    Accurate data on neutron-induced fission cross-sections of actinides are essential for the design of advanced nuclear reactors based either on fast neutron spectra or alternative fuel cycles, as well as for the reduction of safety margins of existing and future conventional facilities. The fission cross-section of 234U was measured at incident neutron energies of 560 and 660 keV and 7.5 MeV with a setup based on `microbulk' Micromegas detectors and the same samples previously used for the measurement performed at the CERN n_TOF facility (Karadimos et al., 2014). The 235U fission cross-section was used as reference. The (quasi-)monoenergetic neutron beams were produced via the 7Li(p,n) and the 2H(d,n) reactions at the neutron beam facility of the Institute of Nuclear and Particle Physics at the `Demokritos' National Centre for Scientific Research. A detailed study of the neutron spectra produced in the targets and intercepted by the samples was performed coupling the NeuSDesc and MCNPX codes, taking into account the energy spread, energy loss and angular straggling of the beam ions in the target assemblies, as well as contributions from competing reactions and neutron scattering in the experimental setup. Auxiliary Monte-Carlo simulations were performed with the FLUKA code to study the behaviour of the detectors, focusing particularly on the reproduction of the pulse height spectra of α-particles and fission fragments (using distributions produced with the GEF code) for the evaluation of the detector efficiency. An overview of the developed methodology and preliminary results are presented.

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

    CERN Document Server

    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...

  9. Measurement of multilayer reflectivities from 8 keV to 130 keV

    DEFF Research Database (Denmark)

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

    1993-01-01

    This paper presents measurements of specular and non-specular reflectivities of a W/Si multilayer with period d=135.1 A. Angular dispersive measurements were performed at 8.05 keY and 59.3 keY, while energy dispersive measurements were made in the range of 17 keV to 130 keY. At an incidence angle...

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

    Energy Technology Data Exchange (ETDEWEB)

    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

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

    Science.gov (United States)

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

    2013-03-01

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

  12. Neutron fluence and energy reconstruction with the IRSN recoil detector μ-TPC at 27 keV, 144 keV and 565 keV

    Energy Technology Data Exchange (ETDEWEB)

    Maire, D.; Lebreton, L.; Richer, J.P. [IRSN, PRP-HOM, SDE, LMDN, 13115 Saint Paul-Lez-Durance (France); Bosson, G.; Bourrion, O.; Guillaudin, O.; Riffard, Q.; Santos, D. [CNRS/IN2P3-UJF-INPG, LPSC, 38000 Grenoble (France)

    2015-07-01

    The French Institute for Radioprotection and Nuclear Safety (IRSN), associated to the French Metrology Institute (LNE), is developing a time projection chamber using a Micromegas anode: μ-TPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize with a primary procedure the energy distribution of neutron fluence in the energy range 8 keV - 1 MeV. The time projection chambers are gaseous detectors, which are able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulated detector response. The μ-TPC is a new reliable detector which enables to measure energy distribution of the neutron fluence without deconvolution or neutron calibration contrary to usual gaseous counters. The μ-TPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27.2 keV, 144 keV and 565 keV are shown and compared to the complete detector simulation. This work shows the first direct

  13. Sputtering of solid neon by keV hydrogen ions

    DEFF Research Database (Denmark)

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

    1986-01-01

    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....

  14. Sputtering of thin and intermediately thick films of solid deuterium by keV electrons

    DEFF Research Database (Denmark)

    Svendsen, Winnie Edith; Thestrup Nielsen, Birgitte; Schou, Jørgen

    1995-01-01

    Sputtering of films of solid deuterium by keV electrons was studied in a cryogenic set-up. The sputtering yield shows a minimum yield of about 4 D2/electron for 1.5 and 2 keV electrons at a thickness slightly larger than the average projected range of the electrons. We suggest that the yield around...

  15. Characteristics of > 290 keV magnetosheath ions

    Directory of Open Access Journals (Sweden)

    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.

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

    DEFF Research Database (Denmark)

    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 ke......V. The escape depth for secondary electrons was studied by means of the equivalent-substrate method (carbon substrate). The results varied from 280 Å at 1 keV to 400 Å 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 ke......V. 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...

  17. Luminescent collisions of He+ and He++ ions with H2 molecules at energies below 2 keV

    Science.gov (United States)

    Pranszke, B.; Werbowy, S.; Miotk, R.; Borkowski, K. J.; Kowalski, A.

    2013-10-01

    Spectroscopic studies of collisions between He+ and He++ ions with H2 gas target have been performed in the 200-600 nm wavelength range. Atomic lines of hydrogen Balmer series and several helium lines were identified and their excitation functions between 50 eV and 1 keV (2 keV for He++) were determined.

  18. Solar Wind ~20-300 keV Superhalo Electrons

    Science.gov (United States)

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

    2014-12-01

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

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

    Science.gov (United States)

    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).

  20. Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He[sup 2+]-He collisions

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, D.; Dagnac, R. (Toulouse-3 Univ., 31 (France). Centre de Physique Atomique)

    1992-06-14

    We studied the single-electron capture as well as the direct processes occurring when a He[sup 2+] ion is scattered by a He target. Doubly differential cross sections were measured for single-electron capture with a collision energy ranging from 2 to 8 keV and a scattering angle varying from 10' to 3[sup o]30' (laboratory frame). Single-electron capture into excited states of He[sup +] was found to be the dominant process, confirming a previous experimental study. Elastic scattering and ionization differential cross sections were measured for E = 6 keV. (Author).

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

    CERN Document Server

    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.

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

    DEFF Research Database (Denmark)

    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 ke......V. 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......V. The escape depth for secondary electrons was studied by means of the equivalent-substrate method (carbon substrate). The results varied from 280 Å at 1 keV to 400 Å 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 ke...

  3. Spectral and temporal properties of long GRBs detected by INTEGRAL from 3 keV to 8 MeV

    DEFF Research Database (Denmark)

    Martin-Carrillo, A.; Topinka, M.; Hanlon, L.;

    2010-01-01

    Since its launch in 2002, INTEGRAL has triggered onmore than 78 g –ray bursts in the 20-200 keV energy range with the IBIS/ISGRI instrument. Almost 30% of these bursts occurred within the fully coded field of view of the JEM-X detector (5) which operates in the 3-35 keV energy range. A detailed...

  4. Sputtering of cryogenic films of hydrogen by keV ions

    DEFF Research Database (Denmark)

    Schou, Jørgen; Hilleret, Noel

    2009-01-01

    The sputtering yield induced by keV hydrogen ions measured at CERN and at Risø National Laboratory for solid H2 and D2 at temperatures below 4.2 K decreases with increasing film thickness from about 100 x 10(15)molecules/cm2. For a film thickness comparable to or larger than the ion range the dat...

  5. W/SiC x-ray multilayers optimized for use above 100 keV

    DEFF Research Database (Denmark)

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

    2003-01-01

    and thermal stability in both periodic and depth-graded W/SiC structures, whereas synchrotron radiation was used to measure the hard x-ray reflectance of a depth-graded multilayer designed specifically for use in, the range Esimilar to150-170 keV. We have modeled the hard x-ray reflectance using newly derived...

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

    DEFF Research Database (Denmark)

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

    2002-01-01

    and thermal stability in both periodic and depth-graded W/SiC structures, while synchrotron radiation was used to measure the hard X-ray reflectance of a depth-graded multilayer designed specifically for use in the range Esimilar to150 - 170 keV. We have modeled the hard X-ray reflectance using newly...

  7. Early SPI/INTEGRAL measurements of galactic 511 keV line emission from positron annihilation

    OpenAIRE

    Jean, P.; Knoedlseder, J.; Lonjou, V.; Allain, M.; Roques, J. -P.; Skinner, G.K.; Teegarden, B.J.; Vedrenne, G.; von Ballmoos, P.; Cordier, B.; Caraveo, P.; Diehl, R.; Durouchoux, Ph.; Mandrou, P.; Matteson, J.

    2003-01-01

    We report the first measurements of the 511 keV line emission from the Galactic Centre (GC) region performed with the spectrometer SPI on the space observatory INTEGRAL (International Gamma-Ray Astrophysics Laboratory). Taking into account the range of spatial distribution models which are consistent with the data, we derive a flux of $9.9^{+4.7}_{-2.1} \\times 10^{-4}$ ph cm$^{-2}$ s$^{-1}$ and an intrinsic line width of $2.95^{+0.45}_{-0.51}$ keV (FWHM). The results are consistent with other...

  8. Measurement of the {sup 232}Th neutron capture cross section in the region 5 keV-150 keV

    Energy Technology Data Exchange (ETDEWEB)

    Lobo, Georges; Corvi, Franco; Schillebeeckx, Peter; Brusegan, Antonio; Mutti, Paolo [EC-JRC-Institute for Reference Materials and Measurements, Geel (Belgium); Janeva, Natalia [Inst. for Nuclear Research and Nuclear Energy, Bulgarian Academy of Science, Sofia (Belgium)

    2002-08-01

    The average capture cross-section of {sup 232}Th has been measured at the 14.37 m flight path of GELINA, IRMM-Geel, in the energy range from 5 to 150 keV. The capture events were detected by two C{sub 6}D{sub 6} liquid scintillators and the neutron flux was measured with a {sup 10}B-loaded ionisation chamber. The data, corrected with the pulse-height weighting technique, have been normalised to the well-isolated and nearly saturated {sup 232}Th (n, {gamma}) resonances at 21.8 eV and 23.5 eV. Below 15 keV neutron energy, we do not observe the discrepancies, up to 40%, with the evaluated ENDF/B-VI data as reported by Wisshak et al.. Between 5 and 80 keV our results are about 10% systematically above the ENDF/B-VI data and approach the evaluated data between 80 and 100 keV. (author)

  9. Spatial distribution of upstream magnetospheric ≥50 keV ions

    Directory of Open Access Journals (Sweden)

    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

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

    Indian Academy of Sciences (India)

    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.

  11. Measurement of a 127 keV Neutron Field with the Future Standard Spectrometer micro-TPC

    CERN Document Server

    Maire, D; Bosson, G; Bourrion, O; Guillaudin, O; Lamblin, J; Lebreton, L; Mayet, F; Médard, J; Muraz, J F; Petit, M; Richer, J P; Riffard, Q; Santos, D

    2013-01-01

    In order to measure energy of neutron fields, with energy ranging from 8 keV to 1 MeV, a new primary standard is being developed at the IRSN (Institute for Radioprotection and Nuclear Safety). This project, micro-TPC (Micro Time Projection Chamber), carried out in collaboration with the LPSC (Laboratoire de Physique Subatomique et de Cosmologie), is based on the nucleus recoil detector principle. The instrument will be presented with the associated method to measure the neutron energy. This article will emphasize the proton energy calibration procedure and energy measurements of a neutron field produced at 127 keV on the IRSN facility AMANDE. Finally the COMIMAC device, dedicated to the calibration, will be described. This original device, developed at the LPSC, is able to produce proton and electron beams with an accurate energy ranging from 1 keV to 50 keV.

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

    Science.gov (United States)

    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.

  13. Peptide fragmentation by keV ion-induced dissociation

    NARCIS (Netherlands)

    Bari, S.; Hoekstra, R.A.; Schlathölter, T.A.

    2010-01-01

    We have studied multiple ionization and dissociation of a trapped protonated peptide (leucine enkephalin) as induced by keV singly and doubly charged ions (H(+), He(+,) (2+)) to demonstrate the potential of keV ions as a future tool for peptide identification. In contrast to conventional excitation

  14. Characteristics of upstream energetic (E>=50keV) ion events during intense geomagnetic activity

    Science.gov (United States)

    Anagnostopoulos, G. C.; Rigas, A. G.; Sarris, E. T.; Krimigis, S. M.

    1998-05-01

    In this work we examine the statistical presence of some important features of upstream energetic (>=50 keV) ion events under some special conditions in the upstream region and the magnetosphere. The 125 ion events considered in the statistic were observed by the IMP 7 and IMP 8 spacecraft, at ~35RE from the Earth, during nine long time intervals of a total of 153 hours. The time intervals analyzed were selected under the following restrictions: existence of high proton flux (i.e., >=900 pcm-2s-1sr-1) and of a great number of events (an occurrence frequency of ~10 events per 12 hours in the whole statistics) in the energy range 50-220 keV. The most striking findings are the following: (1) The upstream events were observed during times with high values of the geomagnetic activity index Kp(>=3-) (2) all of the upstream events (100%) have energy spectra extending up to energies E>=290keV (3) 86% of these events are accompanied by relativistic (E>=220keV) electrons; and (4) the majority of the upstream ion events (82%) showed noninverse velocity dispersion during their onset phase (22% of the events showed forward velocity dispersion, and 60% showed no velocity dispersion at all when 5.5-min averaged observations were analyzed). Further statistical analysis of this sample of upstream particle events shows that the 50- to 220-keV proton flux shows a positive correlation with the following parameters: the Kp index of geomagnetic activity and the flux of the high-energy (290-500 keV) protons and (>=220 keV) electrons. More specific findings are the following: (1) The spectral index γ for a power law distribution of ions detected by the National Oceanic and Atmospheric Administration Energetic Particle Experiment (EPE) instrument (50=220-keV electrons increases with the time duration of upstream events. We infer that the vast majority of the upstream ion events considered in this study (under conditions of intense particle activity in the upstream region and enhanced

  15. Magnetic dipole moment and keV neutrino dark matter

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Chao-Qiang, E-mail: geng@phys.nthu.edu.tw [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China); Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan (China); Takahashi, Ryo, E-mail: ryo.takahasi88@gmail.com [Department of Physics, National Tsing Hua University, Hsinchu 300, Taiwan (China)

    2012-04-04

    We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.

  16. Magnetic dipole moment and keV neutrino dark matter

    CERN Document Server

    Geng, Chao-Qiang

    2012-01-01

    We study magnetic dipole moments of right-handed neutrinos in a keV neutrino dark matter model. This model is a simple extension of the standard model with only right-handed neutrinos and a pair of charged particles added. One of the right-handed neutrinos is the candidate of dark matter with a keV mass. Some bounds on the dark matter magnetic dipole moment and model parameters are obtained from cosmological observations.

  17. Dosimetry at a 400 keV accelerator

    DEFF Research Database (Denmark)

    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....

  18. Resonance neutron capture in {sup 60}Ni below 450 keV

    Energy Technology Data Exchange (ETDEWEB)

    Corvi, F.; Fioni, G. E-mail: gfioni@cea.fr; Gunsing, F.; Mutti, P.; Zanini, L

    2002-01-28

    High-resolution neutron capture cross-section measurements on {sup 60}Ni have been performed at the Geel Linear Accelerator in the energy range from 1 to 450 keV. An experimentally determined weighting function, obtained by a total energy detection set-up, has been applied to the measured capture spectra. The parameters of 275 resonances have been determined in a recent reanalysis using the FANAC R-matrix shape fitting code. Accurate values of the maxwellian-averaged capture cross section for stellar temperatures ranging from kT=5 to 100 keV, corresponding to different scenarios of s-process stellar nucleosynthesis, have been calculated. The distributions of partial radiative widths for s- and p-wave resonances have been derived. A correlation of 0.64 between capture and reduced neutron widths is compatible with the presence of nonstatistical effects in the capture of {sup 60}Ni.

  19. Resonance neutron capture in sup 6 sup 0 Ni below 450 keV

    CERN Document Server

    Corvi, F; Gunsing, F; Mutti, P; Zanini, L

    2002-01-01

    High-resolution neutron capture cross-section measurements on sup 6 sup 0 Ni have been performed at the Geel Linear Accelerator in the energy range from 1 to 450 keV. An experimentally determined weighting function, obtained by a total energy detection set-up, has been applied to the measured capture spectra. The parameters of 275 resonances have been determined in a recent reanalysis using the FANAC R-matrix shape fitting code. Accurate values of the maxwellian-averaged capture cross section for stellar temperatures ranging from kT=5 to 100 keV, corresponding to different scenarios of s-process stellar nucleosynthesis, have been calculated. The distributions of partial radiative widths for s- and p-wave resonances have been derived. A correlation of 0.64 between capture and reduced neutron widths is compatible with the presence of nonstatistical effects in the capture of sup 6 sup 0 Ni.

  20. Compton polarimeter for 10-30 keV x rays

    Science.gov (United States)

    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.

  1. Compton polarimeter for 10–30 keV x rays

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. Irradiation damage in aluminium single crystals produced by 50-keV aluminium and copper ions

    DEFF Research Database (Denmark)

    Henriksen, L.; Johansen, A.; Koch, J.

    1968-01-01

    Aluminium single crystals, thin enough to be examined by electron microscopy, have been irradiated with 50-keV aluminium and copper ions. The irradiation fluxes were in the range 1011–1014 cm−2 s−1 and the doses were from 6 × 1012 to 6 × 1014 cm−2. Irradiation along either a or a direction produc...

  3. Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(Tl) scintillator

    Energy Technology Data Exchange (ETDEWEB)

    Schlosser, D.M., E-mail: dieter.schlosser@pnsensor.de [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Huth, M.; Hartmann, R. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Abboud, A.; Send, S. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Conka-Nurdan, T. [Türkisch-Deutsche Universität, Sakinkaya Cad. 86, Beykoz, 34820 Istanbul (Turkey); Shokr, M.; Pietsch, U. [Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany); Strüder, L. [PNSensor GmbH, Sckellstraße 3, 81667 München (Germany); Universität Siegen, Walter-Flex-Straße 3, 57072 Siegen (Germany)

    2016-01-01

    By combining a low noise fully depleted pnCCD detector with a CsI(Tl) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 µm, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9–13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 µm only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive {sup 57}Co source. - Highlights: • Position and energy resolving pnCCD+CsI(Tl) detector for energies from 1-150 keV • Detection in the pnCCD (122keV): 1% energy and <75µm spatial resolution • Detection in the scintillator (122keV): 9-12% energy and ~30µm spatial resolution.

  4. Erosion of solid neon by keV electrons

    DEFF Research Database (Denmark)

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

    1986-01-01

    The erosion of solid neon by keV electrons has been studied experimentally and theoretically. Electronic sputtering as well as temperature-enhanced sublimation are investigated by a frequency-change measurement on a quartz crystal or in some cases by the change in intensity of reflected electrons....... 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...

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

    CERN Document Server

    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...

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

    Science.gov (United States)

    Earnhart, Jonathan Raby Dewitt

    The objective of this work is to investigate Compton camera technology for spectroscopic imaging of gamma rays in the 100keV to 1MeV range. An efficient, specific purpose Monte Carlo code was developed to investigate the image formation process in Compton cameras. The code is based on a pathway sampling technique with extensive use of variance reduction techniques. The code includes detailed Compton scattering physics, including incoherent scattering functions, Doppler broadening, and multiple scattering. Experiments were performed with two different camera configurations for a scene containing a 75Se source and a 137Cs source. The first camera was based on a fixed silicon detector in the front plane and a CdZnTe detector mounted in the stage. The second camera configuration was based on two CdZnTe detectors. Both systems were able to reconstruct images of 75Se, using the 265keV line, and 137Cs, using the 662keV line. Only the silicon-CdZnTe camera was able to resolve the low intensity 400keV line of 75Se. Neither camera was able to reconstruct the 75Se source location using the 136keV line. The energy resolution of the silicon-CdZnTe camera system was 4% at 662keV. This camera reproduced the location of the 137Cs source by event circle image reconstruction with angular resolutions of 10° for a source on the camera axis and 14° for a source 30° off axis. Typical detector pair efficiencies were measured as 3 x 10-11 at 662keV. The dual CdZnTe camera had an energy resolution of 3.2% at 662keV. This camera reproduced the location of the 137Cs source by event circle image reconstruction with angular resolutions of 8° for a source on the camera axis and 12° for a source 20° off axis. Typical detector pair efficiencies were measured as 7 x 10-11 at 662keV. Of the two prototype camera configurations tested, the silicon-CdZnTe configuration had superior imaging characteristics. This configuration is less sensitive to effects caused by source decay cascades and random

  7. KevJumba and the Adolescence of YouTube

    Science.gov (United States)

    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…

  8. Sputtering of solid nitrogen by keV helium ions

    DEFF Research Database (Denmark)

    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...

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

    DEFF Research Database (Denmark)

    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...

  10. The Context for IMAP: Voyager and INCA Observations of the Heliosheath at E > 5 keV

    Science.gov (United States)

    Krimigis, Stamatios M.

    2016-04-01

    The basic premise of the proposed Interstellar Mapping and Acceleration Probe (IMAP) is detailed scientific understanding of the Heliosheath (HS) and beyond, a region of space explored in situ by Voyager 1 (V1) since 2004, Voyager 2 (V2) since 2007, and remotely via energetic neutral atoms (ENA) by the Cassini/INCA (Ion and Neutral CAmera) since 2003 and IBEX since 2009. The IMAP instrumentation proposed for this purpose combines and extends the IBEX and INCA ENA energy ranges (0.3- 20 keV and 3-200 keV, for low and high energy, respectively). All three missions-Voyagers, Cassini/INCA, and IBEX- have made discovery-class measurements in the HS, the Voyagers providing in situ ion intensities at E > 30 keV, while INCA images ENA in the range 5 INCA ENA allows for the possibility of observing the intensity and time evolution of ions in the HS, thought to give rise to the ENAs via charge-exchange, and the resultant ENA images in the inner heliosphere and their spatial and/or temporal variability. Unfortunately, no such "ground truth" ion measurements are possible at Voyager in the ENA energy range imaged by IBEX. Some of the key findings from the Voyager and Cassini/INCA measurements are as follows: (1) The HS contains a hot plasma population that carries a substantial part (30-50 %) of the total pressure at E > 5 keV, the rest residing below that range, resulting in a beta (particle/magnetic pressure) always > 1, typically >10. (2) The width of the HS in the direction of V1 is ~ 30 AU, but is thought to be larger (40-70 AU) in the southern ecliptic where V2 currently travels.. (3) The ENA intensities at E > 5 keV exhibit a correlation with the solar cycle (SC) over the period 2003 to 2015, with minimum intensities in the anti-nose direction observed ~ 1.5 yrs after solar minimum followed by a recovery thereafter. (4) The in situ ion measurements at V2 within the HS also show a similar SC dependence. The totality of the observations, together with the near

  11. DISPLACEMENT CASCADE SIMULATION IN TUNGSTEN UP TO 200 KEV OF DAMAGE ENERGY AT 300, 1025, AND 2050 K

    Energy Technology Data Exchange (ETDEWEB)

    Setyawan, Wahyu; Nandipati, Giridhar; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

    2015-09-22

    We generated molecular dynamics database of primary defects that adequately covers the range of tungsten recoil energy imparted by 14-MeV neutrons. During this semi annual period, cascades at 150 and 200 keV at 300 and 1025 K were simulated. Overall, we included damage energy up to 200 keV at 300 and 1025 K, and up to 100 keV at 2050 K. We report the number of surviving Frenkel pairs (NF) and the size distribution of defect clusters. The slope of the NF curve versus cascade damage energy (EMD), on a log-log scale, changes at a transition energy (μ). For EMD > μ, the cascade forms interconnected damage regions that facilitate the formation of large clusters of defects. At 300 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 266 and 335, respectively. Similarly, at 1025 K and EMD = 200 keV, the largest size of interstitial cluster and vacancy cluster is 296 and 338, respectively. At 2050 K, large interstitial clusters also routinely form, but practically no large vacancy clusters do

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

    CERN Document Server

    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...

  13. Measurements of electron detachment cross sections in 10-50 keV impact energy H{sup {minus}} + collisions

    Energy Technology Data Exchange (ETDEWEB)

    Seely, D.G. [Albion College, MI (United States); Sen, A.; Kvale, T.J. [Univ. of Toledo, OH (United States)

    1996-05-01

    Absolute cross sections for the single- and double-electron detachment ({sigma}{sub {minus}10} and {sigma}{sub {minus}11}, respectively) in collisions between H{sup {minus}} and methane have been measured in the energy range of 10-50 keV. A well-collimated H{sup {minus}} ion beam was accelerated into a gas target cell containing methane and the scattered H{sup {minus},0,+} beam components of the collision products were magnetically separated and simultaneously measured by separate detectors. The cross sections were determined by quadratic least squares fits of the scattered-beam growth curves. In the present energy region, {sigma}{sub {minus}10} exhibits a maximum at around 20 keV impact energy and then monotonically decreases with increasing impact energy. However, {sigma}{sub {minus}11} displays a different energy dependence by monotonically increasing with increasing impact energy until about 25 keV and thereafter remaining relatively constant.

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

    Indian Academy of Sciences (India)

    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.

  15. Proximity functions for electrons up to 10 keV

    Energy Technology Data Exchange (ETDEWEB)

    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).

  16. Single ionization of helium by 40--3000-keV antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Moller, S.P.; Pedersen, J.O.P.; Tang-Petersen, S.; Uggerhoj, E. (Institute of Physics, University of Aarhus, DK-8000 Aarhus C (Denmark)); Elsener, K. (CERN, CH-1211 Geneva (Switzerland)); Morenzoni, E. (PSI, CH-5234 Villigen (Switzerland))

    1990-06-01

    Measurements of single-ionization cross sections for antiproton impact on helium atoms are reported for impact energies ranging from 40 keV to 3 MeV. It is found that the measured cross sections are in good agreement with recent theoretical estimates based on the continuum-distorted-wave approximation. From a comparison with similar proton data, the ratio between antiproton and proton results is obtained. The energy dependence of this ratio is compared with various theoretical estimates and explained as a result of polarization and binding effects.

  17. Single ionization of helium by 40-3000-keV antiprotons

    Science.gov (United States)

    Andersen, L. H.; Hvelplund, P.; Knudsen, H.; Møller, S. P.; Pedersen, J. O. P.; Tang-Petersen, S.; Uggerhøj, E.; Elsener, K.; Morenzoni, E.

    1990-06-01

    Measurements of single-ionization cross sections for antiproton impact on helium atoms are reported for impact energies ranging from 40 keV to 3 MeV. It is found that the measured cross sections are in good agreement with recent theoretical estimates based on the continuum-distorted-wave approximation. From a comparison with similar proton data, the ratio between antiproton and proton results is obtained. The energy dependence of this ratio is compared with various theoretical estimates and explained as a result of polarization and binding effects.

  18. Seeded quantum FEL at 478 keV

    Energy Technology Data Exchange (ETDEWEB)

    Guenther, Marc [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Thirolf, Peter; Seggebrock, Thorben [Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany); Habs, Dietrich [Max-Planck-Institut fuer Quantenoptik, Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, Garching (Germany)

    2012-07-01

    We present for the first time a concept for a seeded {gamma} quantum Free Electron Laser (QFEL) at 478 keV (transition in {sup 7}Li). To produce a highly intense and coherent {gamma} beam, we intend to use a seeded FEL scheme. Important for the production of a highly brilliant and coherent {gamma} beam are novel refractive {gamma} lenses for focusing and an efficient monochromator, allowing to generate a very intense and coherent seed beam. To realize such a coherent {gamma} beam at 478 keV (1/38 A), it is suitable to use a quantum FEL design based on a new ''asymmetric'' laser-electron Compton back scattering scheme as pursued for the MeGaRay and ELI-NP facilities. Here the pulse length of the laser is much longer than the electron bunch length, equivalent to a {gamma}-FEL with laser wiggler. The coherence of a seeded QFEL can open up totally new areas of fundamental physics and applications. Especially, 478 keV can be attractive for ''green energy'' and life-science research, such as the detection of Li deposition in the brain for manic-depressive psychosis treatment with high spatial resolution or isotope-specific nuclear waste management and treatment.

  19. The Dynamic Range of LZ

    OpenAIRE

    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...

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

    Science.gov (United States)

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

    2006-01-01

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

  1. Charge state distributions and charge exchange cross sections of carbon in helium at 30-258 keV

    Science.gov (United States)

    Maxeiner, Sascha; Seiler, Martin; Suter, Martin; Synal, Hans-Arno

    2015-10-01

    With the introduction of helium stripping in radiocarbon (14C) accelerator mass spectrometry (AMS), higher +1 charge state yields in the 200 keV region and fewer beam losses are observed compared to nitrogen or argon stripping. To investigate the feasibility of even lower beam energies for 14C analyses the stripping characteristics of carbon in helium need to be further studied. Using two different AMS systems at ETH Zurich (myCADAS and MICADAS), ion beam transmissions of carbon ions for the charge states -1, +1, +2 and +3 were measured in the range of 258 keV down to 30 keV. The correction for beam losses and the extraction of charge state yields and charge exchange cross sections will be presented. An increase in population of the +1 charge state towards the lowest measured energies up to 75% was found as well as agreement with previous data from literature. The findings suggest that more compact radiocarbon AMS systems are possible and could provide even higher efficiency than current systems operating in the 200 keV range.

  2. Observational consistency and future predictions for a 3.5 keV ALP to photon line

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, Pedro D.; Conlon, Joseph P.; Day, Francesca V.; Marsh, M.C. David; Rummel, Markus [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP (United Kingdom)

    2015-04-09

    Motivated by the possibility of explaining the 3.5 keV line through dark matter decaying to axion-like particles that subsequently convert to photons, we study ALP-photon conversion for sightlines passing within 50 pc of the galactic centre. Conversion depends on the galactic centre magnetic field which is highly uncertain. For fields at low or mid-range of observational estimates (10–100 μG), no observable signal is possible. For fields at the high range of observational estimates (a pervasive poloidal mG field over the central 150 pc) it is possible to generate sufficient signal to explain recent observations of a 3.5 keV line in the galactic centre. In this scenario, the galactic centre line signal comes predominantly from the region with z>20pc, reconciling the results from the Chandra and XMM-Newton X-ray telescopes. The dark matter to ALP to photon scenario also naturally predicts the non-observation of the 3.5 keV line in stacked galaxy spectra. We further explore predictions for the line flux in galaxies and suggest a set of galaxies that is optimised for observing the 3.5 keV line in this model.

  3. Search for 511 keV emission in satellite galaxies of the Milky Way with INTEGRAL/SPI

    Science.gov (United States)

    Siegert, Thomas; Diehl, Roland; Vincent, Aaron C.; Guglielmetti, Fabrizia; Krause, Martin G. H.; Boehm, Celine

    2016-10-01

    Context. The positron (e+) annihilation γ-ray signal in the Milky Way (MW) shows a puzzling morphology: a very bright bulge and a very low surface-brightness disk. A coherent explanation of the e+ origin, propagation through the Galaxy and subsequent annihilation in the interstellar medium has not yet been found. Tentative explanations involve e+s from radioactivity, X-ray binaries, and dark matter (DM). Aims: Dwarf satellite galaxies (DSGs) are believed to be dominated by DM and hence are promising candidates in the search for 511 keV emission as a result of DM annihilation into e+e--pairs. The goal of this study is to constrain possible 511 keV γ-ray signals from 39 DSGs of the MW and to test the annihilating DM scenario. Methods: We used the spectrometer SPI on INTEGRAL to extract individual spectra for the studied objects in the range 490-530 keV. As the diffuse galactic 511 keV emission dominates the overall signal, we modelled the large-scale morphology of the MW accordingly and included this in a maximum likelihood analysis. Alternatively, a distance-weighted stacked spectrum was determined, representing an average DSG seen in 511 keV. Results: Only Reticulum II (Ret II) shows a 3.1σ signal. Five other sources show tentative 2σ signals. The ratio of mass to 511 keV luminosity, Υ511, shows a marginal trend towards higher values for intrinsically brighter objects in contrast to the mass-to-light ratio, ΥV in the V band, which is generally used to uncover DM in DSGs. Conclusions: All derived 511 keV flux values or upper limits are above the flux level implied by a DM interpretation of the MW bulge signal. The signal detected from Ret II is unlikely to be related to a DM origin alone, otherwise, the MW bulge would be ~100 times brighter in 511 keV than what is seen with SPI. Ret II is exceptional considering the DSG sample and rather points to enhanced recent star formation activity if its origins are similar to processes in the MW. Understanding this

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

    CERN Document Server

    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.

  5. Relic keV sterile neutrinos and reionization.

    Science.gov (United States)

    Biermann, Peter L; Kusenko, Alexander

    2006-03-10

    A sterile neutrino with a mass of several keV can account for cosmological dark matter, as well as explain the observed velocities of pulsars. We show that x rays produced by the decays of these relic sterile neutrinos can boost the production of molecular hydrogen, which can speed up the cooling of gas and the early star formation, which can, in turn, lead to a reionization of the Universe at a high enough redshift to be consistent with the Wilkinson Microwave Anisotropy Probe results.

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  7. 7.1 keV sterile neutrino constraints from X-ray observations of 33 clusters of galaxies with Chandra ACIS

    CERN Document Server

    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...

  8. Evolution of nanodot morphology on polycarbonate (PC) surfaces by 40 keV Ar{sup +}

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Meetika, E-mail: meetika89@gmail.com; Chawla, Mahak; Gupta, Divya; Shekhawat, Nidhi; Sharma, Annu; Aggarwal, Sanjeev [Department of Physics, Kurukshetra University, Kurukshetra - 136119 (India)

    2016-05-06

    In the present paper we have discussed the effect of 40 keV Ar{sup +} ions irradiation on nanoscale surface morphology of Polycarbonate (PC) substrate. Specimens were sputtered at off normal incidences of 30°, 40° and 50° with the fluence of 1 × 10{sup 16} Ar{sup +}cm{sup −2}. The topographical behaviour of specimens was studied by using Atomic Force Microscopy (AFM) technique. AFM study demonstrates the evolution of nano dot morphology on PC specimens on irradiating with 1 × 10{sup 16} Ar{sup +}cm{sup −2}. Average size of dots varied from 37-95 nm in this specified range of incidence while density of dots varied from 0.17-3.0 × 107 dotscm{sup −2}. Such variations in morphological features have been supported by estimation of ion range and sputtering yield through SRIM simulations.

  9. Determination of arsenic, antimony, and bismuth in silicon using 200 keV. cap alpha. -particle backscattering

    Energy Technology Data Exchange (ETDEWEB)

    Hnatowicz, V.; Kvitek, J. (Ceskoslovenska Akademie Ved, Rez. Ustav Jaderne Fyziky); Krejci, P.; Rybka, V. (Tesla, Prague (Czechoslovakia)); Pelikan, L. (Technical University of Prague (Czechoslovakia). Dept. of Microelectronics)

    1982-11-16

    Concentration profiles of As, Sb, and Bi implanted into Si are studied using backscattering of the 200 keV ..cap alpha..-particles. A conventional ion implanter serves as a source of analyzing beam and the scattered particles are detected using a silicon surface barrier detector. Measured projected ranges R/sub P/ of implanted atoms are found to be in satisfactory agreement with theoretical predictions.

  10. Emission lines between 1 and 2 keV in Cometary X-ray Spectra

    CERN Document Server

    Ewing, Ian; Bodewits, Dennis; Dennerl, Konrad; Lisse, Carey M; Wolk, Scott J

    2012-01-01

    We present the detection of new cometary X-ray emission lines in the 1.0 to 2.0 keV range using a sample of comets observed with the Chandra X-ray observatory and ACIS spectrometer. We have selected 5 comets from the Chandra sample with good signal-to-noise spectra. The surveyed comets are: C/1999 S4 (LINEAR), C/1999 T1 (McNaught-Hartley), 153P/2002 (Ikeya-Zhang), 2P/2003 (Encke), and C/2008 8P (Tuttle). We modeled the spectra with an extended version of our solar wind charge exchange (SWCX) emission model (Bodewits et al. 2007). Above 1 keV, we find Ikeya-Zhang to have strong emission lines at 1340 and 1850 eV that we identify as being created by solar wind charge exchange lines of Mg XI and Si XIII, respectively, and weaker emission lines at 1470, 1600, and 1950 eV formed by SWCX of Mg XII, Mg XI, and Si XIV, respectively. The Mg XI and XII and Si XIII and XIV lines are detected at a significant level for the other comets in our sample (LS4, MH, Encke, 8P), and these lines promise additional diagnostics to ...

  11. Effective field theory and keV lines from dark matter

    CERN Document Server

    Krall, Rebecca; Roxlo, Thomas

    2014-01-01

    We survey operators that can lead to a keV photon line from dark matter decay or annihilation. We are motivated in part by recent claims of an unexplained 3.5 keV line in galaxy clusters and in Andromeda, but our results could apply to any hypothetical line observed in this energy range. We find that given the amount of flux that is observable, explanations in terms of decay are more plausible than annihilation, at least if the annihilation is directly to Standard Model states rather than intermediate particles. The decay case can be explained by a scalar or pseudoscalar field coupling to photons suppressed by a scale not far below the reduced Planck mass, which can be taken as a tantalizing hint of high-scale physics. The scalar case is particularly interesting from the effective field theory viewpoint, and we discuss it at some length. Because of a quartically divergent mass correction, naturalness strongly suggests the theory should be cut off at or below the 1000 TeV scale. The most plausible such natural...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-02-25

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

  13. First measurements in search for keV sterile neutrino in tritium beta-decay in the Troitsk nu-mass experiment

    Science.gov (United States)

    Abdurashitov, J. N.; Belesev, A. I.; Chernov, V. G.; Geraskin, E. V.; Golubev, A. A.; Grigorieva, P. V.; Koroteev, G. A.; Likhovid, N. A.; Nozik, A. A.; Pantuev, V. S.; Parfenov, V. I.; Skasyrskaya, A. K.; Tkachev, I. I.; Zadorozhny, S. V.

    2017-06-01

    We present the first results of precision measurements of tritium -decay spectrum in the electron energy range 16-18.6 keV by the Troitsk nu-mass experiment. The goal is to find distortions that may be caused by the existence of heavy sterile neutrinos. A signature would correspond to a kink in the spectrum with characteristic shape and end point shifted by the value of a heavy neutrino mass. We set new upper limits to the neutrino mixing matrix element U e4 2 , which improve existing limits by a factor of 2 to 5 in the mass range of 0.1-2 keV.

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

    CERN Document Server

    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...

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

    Energy Technology Data Exchange (ETDEWEB)

    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. The 14C(n,γ) cross section between 10 keV and 1 M

    CERN Document Server

    Reifarth, R; Forssén, C; Besserer, U; Couture, A; Dababneh, S; Dörr, L; Görres, J; Haight, R C; Käppeler, F; Mengoni, A; O'Brien, S; Patronis, N; Plag, R; Rundberg, R S; Wiescher, M; Wilhelmy, J B

    2008-01-01

    The neutron capture cross section of 14C is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The 14C(n,γ) reaction is also important for the validation of the Coulomb dissociation method, where the (n,γ) cross section can be indirectly obtained via the time-reversed process. So far, the example of 14C is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the 14C(n,γ) reaction with neutron energies ranging from 20 to 800 keV.

  17. Microstructural investigation of alumina implanted with 30 keV nitrogen ions

    Energy Technology Data Exchange (ETDEWEB)

    Shikha, Deep; Jha, Usha [Department of Applied Chemistry, BIT Mesra, Ranchi 835 215, Jharkhand (India); Sinha, S.K. [Department of Applied Physics, BIT Mesra, Ranchi 835 215, Jharkhand (India)], E-mail: sksinha@bitmesra.ac.in; Barhai, P.K. [Department of Applied Physics, BIT Mesra, Ranchi 835 215, Jharkhand (India); Sarkhel, G. [Department of Polymer Engineering, BIT Mesra, Ranchi 835 215, Jharkhand (India); Nair, K.G.M.; Dash, S.; Tyagi, A.K. [Material Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Kothari, D.C. [Department of Physics, Mumbai University, Vidyanagri, Santacruz (E), Mumbai 400 098 (India)

    2007-11-15

    Among ceramics, alumina is being widely used as biomaterials now these days. It is being used as hip joints, tooth roots etc. Ion implantation has been employed to modify its surface without changing it bulk properties. 30 keV nitrogen with varying ion dose ranging from 5 x 10{sup 15} ions/cm{sup 2} to 5 x 10{sup 17} ions/cm{sup 2} is implanted in alumina. Surface morphology has been studied with optical microscope and atomic force microscope (AFM). Improvement in brittleness has been observed with the increase in ion dose. Compound formation and changes in grain size have been studied using X-Ray diffraction (XRD). AlN compound formation is also observed by Fourier transform infrared spectroscopy (FTIR). The change in the grain size is related with the nanohardness and Hall-Petch relationship is verified.

  18. Angular distribution of ejected electrons from 20 keV He/sup +/ impact on He

    Energy Technology Data Exchange (ETDEWEB)

    Tokoro, N.; Takenouchi, S.; Urakawa, J.; Oda, N. (Tokyo Inst. of Tech. (Japan). Research Lab. of Nuclear Reactor)

    1982-10-28

    The angular distributions of ejected electrons in the energy range 5-70 eV have been measured at angles from 30 to 150/sup 0/ for 20 keV He/sup +/ impact on He. The angular dependence of excitation cross sections of autoionisation states 2s/sup 2/ /sup 1/S and 2p/sup 2/ /sup 1/D+2s2p /sup 1/P are in good agreement with previous data measured by Bordenave-Montesquieu et al (Phys. Rev.; A25:245 (1982)). The continuous parts of the electron spectra show symmetrical angular distributions around 90/sup 0/ in the laboratory frame for low-energy electrons (

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Total bremsstrahlung spectra of thick lead compounds produced by {sup 90}Sr beta emitter in photon energy region of 10–100 keV

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Suhansar Jit [Department of Physics, B.B.S.B Polytechnic, Fatehgarh Sahib, Punjab (India); Singh, Tajinder, E-mail: tajindersingh2k9@gmail.com [Department of Physics, Mata Gujri College, Fatehgarh Sahib, Punjab (India); Singh, Doordarshi [Department of Mechanical Engineering, B.B.S.B Engineering College, Fatehgarh Sahib, Punjab (India); Singh, Amrit [Department of Physics, Baba Ajay Singh Khalsa College, Gurdas Nangal, Gurdaspur, Punjab (India); Dhaliwal, A.S. [Department of Physics, Sant Longowal Institute of Engineering & Technology, Longowal (Sangrur), Punjab (India)

    2017-06-15

    Highlights: • Total bremsstrahlung spectra in thick targets of Pb compounds by {sup 90}Sr in energy range 10–100 keV. • Experimental results show better agreement with the model which includes PB in SA up to 30 keV. • At higher photon energy region 30–100 keV the model which describes OB is more accurate. • Experimental results show positive deviations from the entire models at higher energy end spectrum. - Abstract: The total bremsstrahlung spectra in the thick targets of lead acetate trihydrate (Pb(CH{sub 3}COO){sub 2}·3H{sub 2}O), lead nitrate Pb(NO{sub 3}){sub 2} and lead chloride (PbCl{sub 2}) produced by {sup 90}Sr beta particles have been investigated in the photon energy region of 10–100 keV. The experimental bremsstrahlung spectra have been compared with the theoretical models Elwert corrected (non relativistic) Bethe Heitler theory, modified Elwert factor (relativistic) Bethe Heitler theory for ordinary bremsstrahlung and modified Elwert factor (relativistic) Bethe Heitler theory which includes polarization bremsstrahlung in the stripped atom approximation. The experimental results show better agreement with theoretical model that includes polarization bremsstrahlung in stripped approximation in the photon energy region below 30 keV. However, at higher photon energy region 30–100 keV, the theoretical model which describes ordinary bremsstrahlung is more accurate to describe the experimental bremsstrahlung spectra. The experimental results show positive deviations from the entire theoretical models at higher energy end of the spectrum. The results indicate that polarization bremsstrahlung plays important role in the formation of total bremsstrahlung spectra in lead compounds produced by continuous beta particles at low photon energy region of 10–30 keV.

  2. Primordial nucleosynthesis during the keV era

    Energy Technology Data Exchange (ETDEWEB)

    Dimopoulos, S.; Esmailzadeh, R.; Hall, L.J.; Starkman, G.D.

    1987-09-09

    Energetic hadronic and electromagnetic showers in the keV era of the hot big bang are produced by the decays of long lived particles. These showers initiate a new phase of nucleosynthesis. The abundance ratios of D, /sup 3/He, /sup 6/Li and /sup 7/Li are given by fixed points of rate equations, which are determined by nuclear physics not by the nature of the decaying particle. The fixed points are independent of prior abundances, so that constraints from the MeV era of nucleosynthesis evaporate, except for a requirement that /sup 4/He not be underproduced. For example, ..cap omega../sub B/ = 1 and many more than four neutrino species are both possible. Within the accuracy of our calculation (there are uncertainties of at least a factor of three), the abundances agree with those inferred from observations. Considerable /sup 6/Li is produced and must be depleted in both population II halo stars and in the galactic disk. We predict /sup 6/Li, /sup 3/He and D abundances in primordial material which are higher than conventional nucleosynthesis. 8 refs.

  3. Where do the 3.5 keV photons come from? A morphological study of the Galactic Center and of Perseus

    Energy Technology Data Exchange (ETDEWEB)

    Carlson, Eric; Jeltema, Tesla; Profumo, Stefano, E-mail: erccarls@ucsc.edu, E-mail: tesla@ucsc.edu, E-mail: profumo@ucsc.edu [Department of Physics, University of California, Santa Cruz 1156 High St, Santa Cruz, CA 95064 (United States)

    2015-02-01

    We test the origin of the 3.5 keV line photons by analyzing the morphology of the emission at that energy from the Galactic Center and from the Perseus cluster of galaxies. We employ a variety of different templates to model the continuum emission and analyze the resulting radial and azimuthal distribution of the residual emission. We then perform a pixel-by-pixel binned likelihood analysis including line emission templates and dark matter templates and assess the correlation of the 3.5 keV emission with these templates. We conclude that the radial and azimuthal distribution of the residual emission is incompatible with a dark matter origin for both the Galactic center and Perseus; the Galactic center 3.5 keV line photons trace the morphology of lines at comparable energy, while the Perseus 3.5 keV photons are highly correlated with the cluster's cool core, and exhibit a morphology incompatible with dark matter decay. The template analysis additionally allows us to set the most stringent constraints to date on lines in the 3.5 keV range from dark matter decay.

  4. Direct and indirect signal detection of 122 keV photons with a novel detector combining a pnCCD and a CsI(Tl) scintillator

    Science.gov (United States)

    Schlosser, D. M.; Huth, M.; Hartmann, R.; Abboud, A.; Send, S.; Conka-Nurdan, T.; Shokr, M.; Pietsch, U.; Strüder, L.

    2016-01-01

    By combining a low noise fully depleted pnCCD detector with a CsI(Tl) scintillator, an energy-dispersive area detector can be realized with a high quantum efficiency (QE) in the range from below 1 keV to above 100 keV. In direct detection mode the pnCCD exhibits a relative energy resolution of 1% at 122 keV and spatial resolution of less than 75 μm, the pixel size of the pnCCD. In the indirect detection mode, i.e. conversion of the incoming X-rays in the scintillator, the measured energy resolution was about 9-13% at 122 keV, depending on the depth of interaction in the scintillator, while the position resolution, extracted with the help of simulations, was 30 μm only. We show simulated data for incident photons of 122 keV and compare the various interaction processes and relevant physical parameters to experimental results obtained with a radioactive 57Co source.

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

    CERN Document Server

    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...

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

    CERN Document Server

    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, ...

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

    CERN Document Server

    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...

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

    CERN Document Server

    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

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

    CERN Document Server

    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..

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

    Energy Technology Data Exchange (ETDEWEB)

    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

  11. Local and global nucleon optical models from 1 keV to 200 MeV

    CERN Document Server

    Köning, A J

    2003-01-01

    We present new phenomenological optical model potentials (OMPs) for neutrons and protons with incident energies from 1 keV up to 200 MeV, for (near-)spherical nuclides in the mass range 24<=A<=209. They are based on a smooth, unique functional form for the energy dependence of the potential depths, and on physically constrained geometry parameters. For the first time, this enables one to predict basic scattering observables over a broad mass range and over an energy range that covers several orders of magnitude in MeV. Thereby, the necessity of using different OMPs in different energy regions has been removed. Using extensive grid searches and a new computational steering technique, we have obtained optical model parameters for many isotopes separately. We recommend that the resulting, so-called local, optical models be used in theoretical analyses of nuclear data. From these parameterizations, we have also constructed asymmetry-dependent neutron and proton global OMPs that are superior to all other exi...

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

    Indian Academy of Sciences (India)

    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.

  13. IONIZATION AND FRAGMENTATION OF ANTHRACENE UPON INTERACTION WITH keV PROTONS AND alpha PARTICLES

    NARCIS (Netherlands)

    Postma, J.; Bari, S.; Hoekstra, R.; Tielens, A. G. G. M.; Schlathoelter, T.

    2010-01-01

    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 (C(14)H(10)) upon keV H(+) and He(2+) impact using high-resolution time-of-flight mass spectrometry. Extensive f

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

    Science.gov (United States)

    Hindi, M. M.; Kozub, R. L.; Robinson, S. J.

    1994-06-01

    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 1.2×106 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 Surić 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.

  15. SU-E-T-46: A Monte Carlo Investigation of Radiation Interactions with Gold Nanoparticles in Water for 6 MV, 85 KeV and 40 KeV Photon Beams

    Energy Technology Data Exchange (ETDEWEB)

    Flint, D B; O’Brien, D J; McFadden, C H; Wolfe, T; Krishnan, S; Sawakuchi, G O [UT MD Anderson Cancer Center, Houston, TX. (United States); Hallacy, T M [UT MD Anderson Cancer Center, Houston, TX. (United States); Rice University, Houston, TX (United States)

    2015-06-15

    Purpose: To determine the effect of gold-nanoparticles (AuNPs) on energy deposition in water for different irradiation conditions. Methods: TOPAS version B12 Monte Carlo code was used to simulate energy deposition in water from monoenergetic 40 keV and 85 keV photon beams and a 6 MV Varian Clinac photon beam (IAEA phase space file, 10x10 cm{sup 2}, SSD 100 cm). For the 40 and 85 keV beams, monoenergetic 2x2 mm{sup 2} parallel beams were used to irradiate a 30x30x10 µm {sup 3} water mini-phantom located at 1.5 cm depth in a 30x30x50 cm{sup 3} water phantom. 5000 AuNPs of 50 nm diameter were randomly distributed inside the mini-phantom. Energy deposition was scored in the mini-phantom with the AuNPs’ material set to gold and then water. For the 6 MV beam, we created another phase space (PHSP) file on the surface of a 2 mm diameter sphere located at 1.5 cm depth in the water phantom. The PHSP file consisted of all particles entering the sphere including backscattered particles. Simulations were then performed using the new PHSP as the source with the mini-phantom centered in a 2 mm diameter water sphere in vacuum. The g4em-livermore reference list was used with “EMRangeMin/EMRangeMax = 100 eV/7 MeV” and “SetProductionCutLowerEdge = 990 eV” to create the new PHSP, and “SetProductionCutLowerEdge = 100 eV” for the mini-phantom simulations. All other parameters were set as defaults (“finalRange = 100 µm”). Results: The addition of AuNPs resulted in an increase in the mini-phantom energy deposition of (7.5 ± 8.7)%, (1.6 ± 8.2)%, and (−0.6 ± 1.1)% for 40 keV, 85 keV and 6 MV beams respectively. Conclusion: Enhanced energy deposition was seen at low photon energies, but decreased with increasing energy. No enhancement was observed for the 6 MV beam. Future work is required to decrease the statistical uncertainties in the simulations. This research is partially supported from institutional funds from the Center for Radiation Oncology Research, The

  16. 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

    CERN Document Server

    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.

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

    Science.gov (United States)

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

    1997-01-01

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

  18. Inelastic scattering and stopping power of low-energy electrons (0.01-10 keV) in toluene.

    Science.gov (United States)

    García, G; Blanco, F; Grau Carles, A; Grau Malonda, A

    2004-01-01

    In this study, the stopping power for electrons in toluene is reported for incident energies ranging from 10 to 10,000 eV. The present results have been obtained by combining the calculated inelastic electron scattering cross-sections with an experimental energy loss procedure. Calculations have been carried out by means of a quasifree absorption model whose reliability has been checked by comparison with empirical electron scattering total cross section data. Results have been compared with the high-energy stopping power data available in the literature. For energies below 1 keV these are the first results of the stopping power for electrons in toluene.

  19. Astrophysical S-factor of T(4He, γ)7Li reaction at E cm = 15.7 keV

    Science.gov (United States)

    Bystritsky, V. M.; Dudkin, G. N.; Emets, E. G.; Filipowicz, M.; Krylov, A. R.; Nechaev, B. A.; Nurkin, A.; Padalko, V. N.; Philippov, A. V.; Sadovsky, A. B.

    2017-07-01

    The astrophysical S-factor of the reaction T(4He, γ)7Li is measured for the first time at the center of mass energy E cm = 15.7 keV, lower than the energy range of the Standard Big Bang Nucleosynthesis (SBBN) model. The experiment is performed on a Hall pulsed accelerator (TPU, Tomsk). An acceleration pulse length of 10 μs allows one to suppress the background of cosmic radiation and the ambient medium by five orders of magnitude. A beam intensity of 5 × 1014 4He+ ions per pulse allows one to measure an extremely low reaction yield. The yield of γ-quanta with the energies E γ 0 = 2483.7 keV and E γ 1 = 2006.1 keV is registered by NaI(Tl) detectors with the efficiency ɛ = 0.331 ± 0.026. A method for direct measurement of the background from the chain of reactions T(4He, 4He)T→T(T, 2 n)X→( n, γ) and/or ( n, n'γ) which ends by neutron activation of materials surrounding the target is proposed and implemented in this study. The value of the astrophysical S-factor of the reaction T(4He, γ)7Li S αt ( E cm = 15.7 keV) = 0.091 ± 0.032 keV b provides the choice from the set of experimental data for the astrophysical S αt -factor in favor of experimental data [4] with S αt ( E cm = 0) = 0.1067 ± 0.0064 keV b.

  20. Charging-assisted desorption of deuterium films by keV electrons

    DEFF Research Database (Denmark)

    Schou, Jørgen; Thestrup Nielsen, Birgitte; Pedersen, Thomas Garm

    2009-01-01

    Films of solid deuterium at a temperature around 3 K have been irradiated by 1.5 or 2 keV electrons. The films were deposited on the silver electrode of a quartz crystal microbalance (QCM) suspended below a pumped liquid helium cryostat [1,2]. The thickness of the films ranged from 10 nm to up to 5...... m. The initial film thickness and the mass loss as result of desorption were monitored by the QCM. The electron beam current was kept at about or below 100 nA to avoid beam-induced evaporation. Secondary electron emission was suppressed to a value below 0.01-0.03 electrons/electron by a repeller...... ring at a bias of – 90 V. However, for films thicker than 3-4 times the range of the bombarding electrons, the electron yield suddenly rose to a value close to 0.40. From this secondary electron yield the voltage potential could be determined unambiguously from secondary electron emission curves...

  1. STABILITY OF EXTRATERRESTRIAL GLYCINE UNDER ENERGETIC PARTICLE RADIATION ESTIMATED FROM 2 keV ELECTRON BOMBARDMENT EXPERIMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Maté, B.; Tanarro, I.; Escribano, R.; Moreno, M. A.; Herrero, V. J. [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, E-28006 Madrid (Spain)

    2015-06-20

    The destruction of solid glycine under irradiation with 2 keV electrons has been investigated by means of IR spectroscopy. Destruction cross sections, radiolysis yields, and half-life doses were determined for samples at 20, 40, 90, and 300 K. The thickness of the irradiated samples was kept below the estimated penetration depth of the electrons. No significant differences were obtained in the experiments below 90 K, but the destruction cross section at 300 K was larger by a factor of 2. The radiolysis yields and half-life doses are in good accordance with recent MeV proton experiments, which confirms that electrons in the keV range can be used to simulate the effects of cosmic rays if the whole sample is effectively irradiated. In the low temperature experiments, electron irradiation leads to the formation of residues. IR absorptions of these residues are assigned to the presence CO{sub 2}, CO, OCN{sup −}, and CN{sup −} and possibly to amide bands I to III. The protection of glycine by water ice is also studied. A water ice film of ∼150 nm is found to provide efficient shielding against the bombardment of 2 keV electrons. The results of this study show also that current Monte Carlo predictions provide a good global description of electron penetration depths. The lifetimes estimated in this work for various environments ranging from the diffuse interstellar medium to the inner solar system, show that the survival of hypothetical primeval glycine from the solar nebula in present solar system bodies is not very likely.

  2. Application of the HOTWAXS detector for imaging at higher X-ray energies (10-30 keV)

    Energy Technology Data Exchange (ETDEWEB)

    Bateman, J.E. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom); Duxbury, D.M. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom)], E-mail: d.m.duxbury@rl.ac.uk; Harvey, I.; Helsby, W.I. [Science and Technology Facilities Council, Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington WA4 4AD (United Kingdom); Spill, E.J. [Science and Technology Facilities Council, Rutherford Appleton Laboratory, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0QX (United Kingdom)

    2009-06-01

    The high overall throughput wide angle X-ray scattering (HOTWAXS) gas detector system, aimed at X-ray diffraction (XRD) and wide angle X-ray scattering (WAXS) applications has been a successful user facility on stations 2.1 and 9.3 at the Daresbury SRS offering high-speed data acquisition. The facility has been duplicated on station I22 of the Diamond light source. The energy range covered by stations I22 and 9.3 is very similar varying from 6 to 30 keV, well above the energy range conventionally covered by gas detectors. Here, we report studies of the options for successful operation of HOTWAXS at the upper end of this energy range, made possible by this particular design.

  3. The Dynamic Range of LZ

    CERN Document Server

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

    CERN Document Server

    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. Friction and wear measurements of 50 keV N implanted stainless steels

    Science.gov (United States)

    Ikeyama, Masami; Miyagawa, Soji; Clissold, Ronald A.; Wielunski, Leszek S.; Swain, Michael V.

    1997-05-01

    Features of friction, wear and hardness of 50 keV nitrogen implanted 13Cr type, C and V rich stainless steel was studied. The implantation was carried out at room temperature (300 K) or about 800 K to the doses of 1 × 10 18 and 5 × 10 17 ions/cm 2. Friction coefficient was measured using steel or silicon nitride balls with the loads of 98 to 980 mN. Friction coefficient depended on upper contact ball materials and loads, and changed from an initial value of 0.1 to final values between 0.2 and 0.8. After implantation, the surface became softer due to amorphization, however, it became relatively harder around the projected range of implanted N. 800 K implantation reduced the amorphization and enhanced diffusion of nitrogen. For the silicon nitride ball, implanted surfaces showed a lower friction coefficient than unimplanted region, particularly for 800 K implantation. When the friction coefficient increased, a considerable amount of adhered debris was observed on stainless steel surfaces.

  6. Rutherford Backscattering Spectrometry studies of 100 keV nitrogen ion implanted polypropylene polymer

    Science.gov (United States)

    Chawla, Mahak; Aggarwal, Sanjeev; Sharma, Annu

    2017-09-01

    The effect of nitrogen ion implantation on the structure and composition in polypropylene (PP) polymer has been studied. Implantation was carried out using 100 keV N+ ions at different fluences of 1 × 1015, 1 × 1016 and 1 × 1017 ions cm-2 with beam current density of ∼0.65 μA cm-2. Surface morphological changes in the pre- and post-implanted PP specimens have been studied using Rutherford Backscattering Spectrometry (RBS) and UV-Visible Spectroscopy. The spatial distribution of implantation induced modification in the form of carbonization and dehydrogenation in the near surface region of PP matrix, the projected range, retained dose of implanted nitrogen, the various elements present in the implanted layers and their differential cross-sections have been analyzed using RBS spectra. RUMP simulation yielded an increase in the concentration of carbon near the surface from 33 at.% (virgin) to 42 at.% at fluence of 1 × 1017 N+ cm-2. Further, optical absorption has been found to increase with a shift in the absorption edge from UV towards visible region with increasing fluence. UV-Vis absorption spectra also indicate a drastic decrease in optical energy gap from 4.12 eV (virgin) to 0.25 eV (1 × 1017 N+ cm-2) indicating towards the formation of carbonaceous network in the implanted region. All these changes observed using UV-Visible have been further correlated with the outcomes of the RBS characterization.

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

    CERN Document Server

    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...

  8. The BeppoSAX 2-10 keV Survey

    CERN Document Server

    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...

  9. Making channeling visible: keV noble gas ion trails on Pt(111)

    Energy Technology Data Exchange (ETDEWEB)

    Redinger, A; Standop, S; Michely, T [II Physikalisches Institut, Universitaet zu Koeln, D-50937 Koeln (Germany); Rosandi, Y; Urbassek, H M, E-mail: urbassek@rhrk.uni-kl.de [Fachbereich Physik und Forschungszentrum OPTIMAS, Universitaet Kaiserslautern, Erwin-Schroedinger-Strasse, D-67663 Kaiserslautern (Germany)

    2011-01-15

    The impact of argon and xenon noble gas ions on Pt(111) in grazing incidence geometry are studied through direct comparison of scanning tunneling microscopy images and molecular dynamics simulations. The energy range investigated is 1-15 keV and the angles of incidence with respect to the surface normal are between 78.5{sup 0} and 88{sup 0}. The focus of the paper is on events where ions gently enter the crystal at steps and are guided in channels between the top most layers of the crystal. The trajectories of the subsurface channeled ions are visible as trails of surface damage. The mechanism of trail formation is analyzed using simulations and analytical theory. Significant differences between Xe{sup +} and Ar{sup +} projectiles in damage, in the onset energy of subsurface channeling as well as in ion energy dependence of trail length and appearance are traced back to the projectile and ion energy dependence of the stopping force. The asymmetry of damage production with respect to the ion trajectory direction is explained through the details of the channel shape and subchannel structure as calculated from the continuum approximation of the channel potential. Measured and simulated channel switching in directions normal and parallel to the surface as well as an increase of ions entering into channels from the perfect surface with increasing angles of incidence are discussed.

  10. Quantitative Assessment of Amino Acid Damage upon keV Ion Beam Irradiation Through FTIR Spectroscopy

    Science.gov (United States)

    Huang, Qing; Ke, Zhigang; Su, Xi; Yuan, Hang; Zhang, Shuqing; Yu, Zengliang

    2010-06-01

    Ion beam irradiation induces important biological effects and it is a long-standing task to acquire both qualitative and quantitative assessment of these effects. One effective way in the investigation is to utilize Fourier transformation infrared (FTIR) spectroscopy because it can offer sensitive and non-invasive measurements. In this paper a novel protocol was employed to prepare biomolecular samples in the form of thin and transversely uniform solid films that were suitable for both infrared and low-energy ion beam irradiation experiments. Under the irradiation of N+ and Ar+ ion beams of 25 keV with fluence ranging from 5×1015 ions/cm2 to 2.5×10 ions/cm2, the ion radio-sensitivity of four amino acids, namely, glycine, tyrosine, methionine and phenylalanine, were evaluated and compared. The ion beam irradiation caused biomolecular decomposition accompanied by molecular desorption of volatile species and the damage was dependent on ion type, fluence, energy and types of amino acids. The effectiveness of application of FTIR spectroscopy to the quantitative assessment of biomolecular damage dose effect induced by low-energy ion radiation was thus demonstrated.

  11. Effects of combined irradiation of 500 keV protons and atomic oxygen on polyimide films

    Science.gov (United States)

    Novikov, Lev; Chernik, Vladimir; Zhilyakov, Lev; Voronina, Ekaterina; Chirskaia, Natalia

    2016-07-01

    Polyimide films are widely used on the spacecraft surface as thermal control coating, films in different constuctions, etc. However, the space ionizing radiation of different types can alter the mechanical, optical and electrical properties of polyimide films. For example, it is well known that 20-100 keV proton irradiation causes breaking of chemical bonds and destruction of the surface layer in polyimide, deterioration of its optical properties, etc. In low-Earth orbits serious danger for polymeric materials is atomic oxygen of the upper atmosphere of the Earth, which is the main component in the range of heights of 200-800 km. Due to the orbital spacecraft velocity, the collision energy of oxygen atoms with the surface ( 5 eV) enhances their reactivity and opens additional pathways of their reaction with near-surface layers of materials. Hyperthermal oxygen atom flow causes erosion of the polyimide surface by breaking chemical bonds and forming of volatiles products (primarily, CO and CO _{2}), which leads to mass losses and degradation of material properties. Combined effect of protons and oxygen plasma is expected to give rise to synergistic effects enhancing the destruction of polyimide surface layers. This paper describes experimental investigation of polyimide films sequential irradiation with protons and oxygen plasma. The samples were irradiated by 500 keV protons at fluences of 10 ^{14}-10 ^{16} cm ^{-2} produced with SINP cascade generator KG-500 and 5-20 eV neutral oxygen atoms at fluence of 10 ^{20} cm ^{-2} generated by SINP magnetoplasmodynamics accelerator. The proton bombardment causes the decrease in optical transmission coefficient of samples, but their transmittance recovers partially after the exposure to oxygen plasma. The results of the comparative analysis of polyimide optical transmission spectra, Raman and XPS spectra obtained at different stages of the irradiation of samples, data on mass loss of samples due to erosion of the surface are

  12. Degradation behaviors of electrical properties of GaInP/GaAs/Ge solar cells under <200 keV proton irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Jianmin, Hu [School of Materials Science and Engineering, Harbin Institute of Technologe, Harbin 150001 (China); Acheng College of Harbin Normal University, Harbin 150301 (China); Yiyong, Wu; Jingdong, Xiao; Dezhuang, Yang [School of Materials Science and Engineering, Harbin Institute of Technologe, Harbin 150001 (China); Zhongwei, Zhang [Shanghai Institute of Space Power Sources, Shanghai 200233 (China)

    2008-12-15

    The degradation effects of the GaInP/GaAs/Ge triple-junction solar cells irradiated by <200 keV protons are investigated on the basis of the spectral response analysis and measurements of electric property. The experimental results show that with increasing proton fluence I{sub sc}, V{sub oc} and P{sub max} decrease obviously. The proton energy exhibits an important influence on the degradation effects of the triple-junction cells dependent on the proton penetration range in the cells. As the proton energy is lower than 100 keV, irradiation-induced damage occurs in the top cell, while the irradiation with proton energy higher than 100 keV causes damage mainly in the middle sub-cells. Comparing the changes in the electrical properties of the triple-junction cells, a conclusion can be made that the GaAs middle sub-cell plays a major role in leading to more severe degradation. In this case, the 170 keV protons are suggested to be used to evaluate the performance of the GaAs triple-junction solar cells, for they can produce more severe degradation effects. (author)

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

    CERN Document Server

    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. The Technique of Genetic Transformation Mediated by keV Ion Beam

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Beam Spot Measurement on a 400 keV Electron Accelerator

    DEFF Research Database (Denmark)

    Miller, Arne

    1979-01-01

    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....

  16. Acceleration of one ampere negative ion beams to energies up to 120 keV

    Energy Technology Data Exchange (ETDEWEB)

    Lam, C.; Sluyters, T.

    1977-01-01

    One of the objectives of the BNL Neutral Beam Development Group is to accelerate negative hydrogen ion beams to energies of several hundreds of kilovolts. In a first attempt, negative ions, produced from surface plasma sources, are extracted at around 15 keV and accelerated across a single gap to energies of 120 keV. Beam currents in excess of one ampere have been accelerated.

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

    CERN Document Server

    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.

  18. Evaluation of n + /sup 242/Pu reactions from 10 keV to 20 MeV. [Total cross sections, neutron emission energy dependence

    Energy Technology Data Exchange (ETDEWEB)

    Madland, D.G.; Young, P.G.

    1978-10-01

    An evaluation of the n + /sup 242/Pu cross sections is presented for the neutron energy range of 10 keV to 20 MeV. The total fission and radiative capture cross sections are based upon experimental measurements on /sup 242/Pu. The remaining cross sections, together with the elastic and inelastic angular distributions to low-lying states, were calculated using various reaction models. An expression is presented for the energy dependence of the average number of neutrons produced per fission. The results were placed in ENDF/B-V format and combined with a recent evaluation of data below 10 keV by the Hanford Engineering Development Laboratory, so that a complete data set covering the energy range of 10/sup -5/ eV to 20 MeV is available. 41 references. (JFP)

  19. COCO, a Compton coincidence experiment to study liquid scintillator response in the 1-20 keV energy range

    Energy Technology Data Exchange (ETDEWEB)

    Peron, M.N. (Laboratoire Primaire des Rayonnements Ionisants, CEA/DAMRI, CE Saclay, BP 52, 91193 Gif-sur-Yvette Cedex (France)); Cassette, P. (Laboratoire Primaire des Rayonnements Ionisants, CEA/DAMRI, CE Saclay, BP 52, 91193 Gif-sur-Yvette Cedex (France))

    1994-12-30

    The use of Liquid Scintillation Counting (LSC) as a fundamental radionuclide standardisation method requires a correct description of the physical phenomena occurring during the LSC process. In that framework, a special point of interest is the description of the liquid scintillator response, especially for low-energy electrons, in a region where this response is known to be non-linear. As there is no simple way to produce monoenergetic electrons in the liquid scintillator, we have simulated these electrons using a Compton interaction coincidence method. Due to the energy conservation law, the selection of the energy of the scattered Compton X-ray photon is equivalent to the selection of the energy of a monoenergetic electron. This paper describes the experimental system and the methods used to analyse the experimental results in order to deduce the statistical distribution of the photons emitted by the scintillator. The effects of some artefacts are discussed, including the accidental coincidences and the influence of cascade Compton interactions. ((orig.))

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

    DEFF Research Database (Denmark)

    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 ...

  1. Observations of proton spectra /Ep ranging from 1.0 to 300 keV/ and fluxes at the plasmapause.

    Science.gov (United States)

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

    1973-01-01

    Discussion of proton flux data recorded for 32 samples per spin period by two solid state proton detectors and a three-axis fluxgate magnetometer aboard Explorer 45 which was launched from Kenia into a 220-km-to-5.24 earth radius orbit. The occurrence of an amplifier saturation effect in the presence of high energy protons is noted. Diagrams are included for proton intensities, proton differential flux vs altitude in six energy bands, evolution of proton differential energy spectra through a steep gradient region, omnidirectional fluxes vs altitude, and plasma densities.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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. 1-40-keV fixed-exit monochromator for a wafer mapping TXRF facility

    Science.gov (United States)

    Comin, Fabio; Apostolo, G.; Freund, Andreas K.; Mangiagalli, P.; Navizet, M.; Troxel, C. L.

    1998-12-01

    An industrial facility for the mapping of trace impurities on the surface of 300 mm Silicon wafers will be commissioned at the end of 1998. The elements to be detected range from Na to Hg with a target routine detection limit of 108 atoms/cm2. The monochromator of the facility plays a central role and fulfills the following requirements: ease of operations and fast tuning (one single motor); extended energy range (1 - 40 KeV covered by a fixed exit Si(111) channel cut and multilayer pair); smooth and reliable running (water cooling even in the powerful ESRF undulator beams at high energies). The mechanical structure of the monochromator is based on well-established concepts: an external goniometer transfers the main rotation to the in-vacuum plateau via a hollow differentially pumped feed-through. The optical arrangement shows some novelties: the plateau can be cooled either by water or liquid nitrogen and it holds the convex- concave machined Si(111) channel-cut for fixed exit performances. The shape of the machined surfaces of the crystal helps also on to spread the power density of the beam on the silicon surface. A set of two identical multilayers are also mounted on the plateau and the transition from the Si(111) crystal to the multilayer operation is performed by rotating the wafer main axis by about 180 degrees. The whole facility is centered around the three main components: the monochromator, the wafer handling robots and the two linear arrays of solid state fluorescence detectors.

  5. Local structures of electrons with energies of hundreds of keV in the inner belt and the slot region observed from the Vernov satellite

    Science.gov (United States)

    Kovtyukh, A. S.; Myagkova, I. N.; Bogomolov, A. V.; Bogomolov, V. V.; Panasyuk, M. I.; Svertilov, S. I.

    2016-11-01

    The structure and dynamics of electron fluxes of subrelativistic energies in the range 235-300 keV at L proceeds. The most likely chain of physical mechanisms that could lead to variations in electron fluxes of the inner belt described in this paper is presented. For the first time, the topological effects in stationary distributions of the electrons of the inner belt observed at low altitudes in the South Atlantic Anomaly region are explained.

  6. Fluence to Effective Dose and Effective Dose Equivalent Conversion Coefficients foe Photons from 50 KeV to 10 GeV

    Energy Technology Data Exchange (ETDEWEB)

    Ferrari, A. [Istituto Nazionale di Fisica Nucleare, Milan (Italy); Pelliccioni, M. [Istituto Nazionale di Fisica Nucleare, Frascati (Italy). Lab. Nazionale di Frascati; Pillon, M. [Associazione EUROATOM-ENEA sulla Fusione, Frascati. Rome (Italy)

    1996-07-01

    Effective dose equivalent and effective dose per unit photon fluence have been calculated by the FLUKA code for various geometrical conditions of irradiation of an anthropomorphic phantom placed in a vacuum. Calculations have been performed for monoenergetic photons of energy ranging from 50 keV to 10 GeV. The agreement with the results of other authors, when existing, is generally very satisfactory.

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

    Science.gov (United States)

    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.

  8. Neutron Fluence and Energy Reconstruction with the LNE-IRSN/MIMAC Recoil Detector MicroTPC at 27 keV

    Energy Technology Data Exchange (ETDEWEB)

    Maire, D.; Lebreton, L.; Querre, Ph. [Institute for Radioprotection and Nuclear Safety - IRSN, site of Cadarache, 13115 Saint Paul lez Durance (France); Bosson, G.; Guillaudin, O.; Muraz, J.F.; Riffard, Q.; Santos, D. [Laboratoire de Physique Subatomique et de Cosmologie - LPSCCNRSIN2P3/ UJF/INP, 38000 Grenoble (France)

    2015-07-01

    The French Institute for Radiation protection and Nuclear Safety (IRSN), designated by the French Metrology Institute (LNE) for neutron metrology, is developing a time projection chamber using a Micromegas anode: microTPC. This work is carried out in collaboration with the Laboratory of Subatomic Physics and Cosmology (LPSC). The aim is to characterize the energy distribution of neutron fluence in the energy range 8 keV - 5 MeV with a primary procedure. The time projection chambers are gaseous detectors able to measure charged particles energy and to reconstruct their track if a pixelated anode is used. In our case, the gas is used as a (n, p) converter in order to detect neutrons down to few keV. Coming from elastic collisions with neutrons, recoil protons lose a part of their kinetic energy by ionizing the gas. The ionization electrons are drifted toward a pixelated anode (2D projection), read at 50 MHz by a self-triggered electronic system to obtain the third track dimension. The neutron energy is reconstructed event by event thanks to proton scattering angle and proton energy measurements. The scattering angle is deduced from the 3D track. The proton energy is obtained by charge collection measurements, knowing the ionization quenching factor (i.e. the part of proton kinetic energy lost by ionizing the gas). The fluence is calculated thanks to the detected events number and the simulation of the detector response. The μTPC is a new reliable detector able to measure energy distribution of the neutron fluence without unfolding procedure or prior neutron calibration contrary to usual gaseous counters. The microTPC is still being developed and measurements have been carried out at the AMANDE facility, with neutrons energies going from 8 keV to 565 keV. After the context and the μ-TPC working principle presentation, measurements of the neutron energy and fluence at 27 keV and 144 keV are shown and compared to the complete detector response simulation. This work

  9. Laser-driven 6-16 keV x-ray imaging and backlighting with spherical crystals

    Science.gov (United States)

    Schollmeier, M.; Rambo, P. K.; Schwarz, J.; Smith, I. C.; Porter, J. L.

    2014-10-01

    Laser-driven x-ray self-emission imaging or backlighting of High Energy Density Physics experiments requires brilliant sources with keV energies and x-ray crystal imagers with high spatial resolution of about 10 μ m. Spherically curved crystals provide the required resolution when operated at near-normal incidence, which minimizes image aberrations due to astigmatism. However, this restriction dramatically limits the range of suitable crystal and spectral line combinations. We present a survey of crystals and spectral lines for x-ray backlighting and self-emission imaging with energies between 6 and 16 keV. Ray-tracing simulations including crystal rocking curves have been performed to predict image brightness and spatial resolution. Results have been benchmarked to experimental data using both Sandia's 4 kJ, ns Z-Beamlet and 200 J, ps Z-Petawatt laser systems. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND NO. 2014-15552A.

  10. Enhancement of keV X-rays from low-density cellulose triacetate (TAC) foam targets

    Science.gov (United States)

    Chaurasia, S.; Kaur, Channprit; Borisenko, N. G.; Pasley, J.; Orekhov, A.; Deo, M. N.

    2017-07-01

    The interaction of a high-power laser with a low-density foam target can in some instances result in a significant enhancement in x-ray generation relative to that when the same laser is incident upon a homogenous solid. In this paper, we present x-ray emission studies from foam targets where the density is varied from under-dense to over-dense. The targets are irradiated with the first harmonic of Nd:Glass laser. The laser intensity on the target was approximately 2 × 1014 W/cm2 with the pulse duration of 500 ps. Mass-matched cellulose triacetate foam targets with densities of 2 mg/cc, 4 mg/cc, 7 mg/cc, and 20 mg/cc were used. The areal density presented by the targets on the laser beam axis was held constant at 0.2 mg/cm2 by varying the target thickness in inverse proportion to the density. The x-ray yield in the spectral range (5-8 keV) and (4.5-16 keV) was found to be enhanced by approximately 2.3 times in foam targets with the density of 2 mg/cc (under-dense) compared with foam targets with the density of 20 mg/cc (over-dense).

  11. Characteristic 8 keV X rays possess radiobiological properties of higher-LET radiation.

    Science.gov (United States)

    Shridhar, Ravi; Estabrook, William; Yudelev, Mark; Rakowski, Joseph; Burmeister, Jay; Wilson, George D; Joiner, Michael C

    2010-03-01

    Electronic brachytherapy systems are being developed that can deliver X rays of varying energy depending on the material of a secondary target. A copper target produces characteristic 8 keV X rays. Our aim was to determine whether 8 keV X rays might deliver greater biological effectiveness than megavoltage photons. Cells of the U251 human glioma cell line were used to compare the biological effects of 8 keV X rays and (60)Co gamma rays in terms of relative biological effectiveness (RBE), oxygen enhancement ratio (OER), and DNA damage. The RBE at 50% and 10% survival was 2.6 and 1.9, respectively. At 50% survival, the OER for cells treated with 8 keV X rays was 1.6 compared with 3.0 for (60)Co gamma rays. The numbers of H2AX foci per Gy after treatment with 8 keV X rays and (60)Co gamma rays were similar; however, the size of the foci generated at 8 keV was significantly larger, possibly indicating more complex DNA damage. The mean area of H2AX foci generated by 8 keV X rays was 0.785 microm(2) (95% CI: 0.756-0.814) compared with 0.491 microm(2) (95% CI: 0.462-0.520) for (60)Co gamma rays (P X rays produce two to three times the biological effectiveness of megavoltage photons, with a radiobiological profile similar to higher-LET radiations.

  12. Efficient laser-induced 6-8 keV x-ray production from iron oxide aerogel and foil-lined cavity targets

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, F.; Kay, J. J.; Patterson, J. R.; Kane, J.; Villette, B.; Girard, F.; Reverdin, C.; May, M.; Emig, J.; Sorce, C.; Colvin, J.; Gammon, S.; Jaquez, J.; Satcher, J. H.; Fournier, K. B.

    2012-08-01

    The performance of new iron-based laser-driven x-ray sources has been tested at the OMEGA laser facility for production of x rays in the 6.5–8.5 keV range. Two types of targets were experimentally investigated: low-density iron oxide aerogels (density 6-16 mg/cm36-16 mg/cm3) and stainless steel foil-lined cavity targets (steel thickness 1-5 μm1-5 μm). The targets were irradiated by 40 beams of the OMEGA laser (500 J/beam, 1 ns pulse, wavelength 351 nm). All targets showed good coupling with the laser, with <5%<5% of the incident laser light backscattered by the resulting plasma in all cases (typically <2.5%<2.5%). The aerogel targets produced Te=2Te=2 to 3 keV, ne=0.12-0.2ne=0.12-0.2 critical density plasmas yielding a 40%–60% laser-to-x-ray total conversion efficiency (CE) (1.2%–3% in the Fe K-shell range). The foil cavity targets produced Te~2 keV, Te~2 keV, ne~0.15ne~0.15 critical density plasmas yielding a 60%–75% conversion efficiency (1.6%–2.2% in the Fe K-shell range). Time-resolved images illustrate that the volumetric heating of low-density aerogels allow them to emit a higher K-shell x-ray yield even though they contain fewer Fe atoms. However, their challenging fabrication process leads to a larger shot-to-shot variation than cavity targets.

  13. Anisotropy of >35 keV ions in corotating particle events at 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Richardson, I.G. (Imperial Coll. of Science and Technology, London (UK). Blackett Lab.)

    1985-02-01

    The anisotropy of 35-1000 keV ions in two corotating particle events associated with high-speed solar wind streams at 1 AU is examined in terms of the diffusion-convection propagation model using data from the Energetic Proton Anisotropy Spectrometer on ISEE-3. The calculated diffusive anisotropy in the solar wind frame is found to be sunward and closely field-aligned, with a nearly energy-independent magnitude of approx. 40%. For one stream, using the Voyager 2 data of Decker et al.(1981), a positive gradient of approx. 100%/AU is found for >approx. 50 keV ions between 1 and 4 AU. The observations do not appear to support the scatter-free propagation model and indicate that ions with energies as low as a few tens of keV may be in diffusive equilibrium with the solar wind in this class of events.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. 7 keV sterile neutrino dark matter from split flavor mechanism

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    CERN Document Server

    Higaki, Tetsutaro; Takahashi, Fuminobu

    2014-01-01

    Some of light moduli fields may play an important role in cosmology. We consider a scenario where the saxion dominates the energy density of the Universe and reheats the standard model sector via its dilatonic couplings, while its axionic partner contributes to dark matter decaying into photons via the same operator in supersymmery. Interestingly, for the axion mass $m_a \\simeq 7$ keV and the decay constant $f_a \\simeq 10^{14-15}$ 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.

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

    DEFF Research Database (Denmark)

    Rudakovskyi, Anton; Iakubovskyi, Dmytro

    2016-01-01

    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...... 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...... 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. 511 keV Line Emission from Nearby Spherical Dwarf Galaxies

    CERN Document Server

    Lawson, Kyle

    2016-01-01

    The observed galactic 511 keV line has been interpreted in a number of papers as a possible signal of dark matter annihilation within the galactic bulge. If this is the case then we should expect a similar spectral feature associated with nearby dwarf galaxies which are dark matter dominated. It has recently been argued [1] that the absence of such a signal excludes a dark matter explanation as the major source for the galactic 511 keV line. In the model presented here dark matter in the form of heavy quark nuggets produces the galactic 511 keV emission line through interactions with the visible matter. It is argued, however, that this type of interaction is not subject to the strong dark matter annihilation constraints presented in [1].

  19. Quark nugget dark matter: no contradiction with 511 keV line emission from dwarf galaxies

    Science.gov (United States)

    Lawson, Kyle; Zhitnitsky, Ariel

    2017-02-01

    The observed galactic 511 keV line has been interpreted in a number of papers as a possible signal of dark matter annihilation within the galactic bulge. If this is the case then it is possible that a similar spectral feature may be observed in association with nearby dwarf galaxies. These objects are believed to be strongly dark matter dominated and present a relatively clean observational target. Recently INTEGRAL observations have provided new constraints on the 511 keV flux from nearby dwarf galaxies [1] motivating further investigation into the mechanism by which this radiation may arise. In the model presented here dark matter in the form of heavy quark nuggets produces the galactic 511 keV emission line through interactions with the visible matter. It is argued that this type of interaction is not strongly constrained by the flux limits reported in [2].

  20. Evaluation of the 1077keV gamma-ray emission probability from 68Ga decay

    CERN Document Server

    Huang, X L; Chen, X J; Chen, G C

    2013-01-01

    68Ga decays to the excited states of 68Zn through the electron capture decay mode. New recommended values for the emission probability of 1077keV gamma-ray given by the ENSDF and DDEP databases all use data from absolute measurements. In 2011 Jiang Liyang deduced a new value for 1077keV gamma-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 1077keV gamma-ray is 2.72+-0.16 %.

  1. 24 CFR 5.100 - Definitions.

    Science.gov (United States)

    2010-04-01

    ...” includes dwelling units in a mixed finance project that are assisted by a PHA with capital or operating... assisted under any of the following programs: (1) Public housing; (2) Housing receiving project-based or... title), and the Section 8 project-based certificate or voucher programs (part 983 of this title), and...

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

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez-Rey, D. [Centro de Micro-Analisis de Materiales, Universidad Autonoma de Madrid, C/ Faraday 3, Campus de Cantoblanco, E-28049 Madrid (Spain); Zurro, B.; Baciero, A.; Navarro, M. [Laboratorio Nacional de Fusion, Asociacion Euratom-CIEMAT, Av. Complutense 22, E-28040 Madrid (Spain); Rodriguez-Barquero, L. [Laboratorio de Metrologia de Radiaciones lonizantes, CIEMAT, Av. Complutense 22, E-28040 Madrid (Spain)

    2010-10-15

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

  4. Improved methods for the generation of 24.5 keV neutron beams with possible application to boron neutron capture therapy

    Science.gov (United States)

    Constantine, G.; Baker, L. J.; Taylor, N. P.

    1986-09-01

    The production of epithermal neutron beams, filtered to provide a spectrum in which a small energy range predominates, is of importance for radiobiological research and in the development and calibration of instruments for monitoring intermediate energy neutrons. The penetration characteristics of intermediate energy neutrons in tissue lead to the possibility of application in the field of neutron capture therapy if beams of sufficient intensity and adequate spectral properties can be generated. In this paper methods of utilising the 24.5 keV antiresonance in the iron neutron cross section are described, and the DENIS (depth enhanced neutron intense source) principle by which beam intensities may be optimised is explained. Calculations and experimental measurements in an in-core facility in the DIDO reactor at Harwell have indicated that a DENIS scatterer can achieve a 6-fold improvement in 24.5 keV beam intensity compared with a conventional titanium disc scatterer.

  5. Calculations of stopping powers and inelastic mean free paths for 20 eV-20 keV electrons in 11 types of human tissue.

    Science.gov (United States)

    Tan, Zhenyu; Liu, Wei

    2013-12-01

    Systematic calculations are performed for determining the stopping powers (SP) and inelastic mean free paths (IMFP) for 20 eV-20 keV electrons in 11 types of human tissue. The calculations are based on a dielectric model, including the Born-Ochkur exchange correction. The optical energy loss functions (OELF) are empirically evaluated, because of the lack of available experimental optical data for the 11 tissues under consideration. The evaluated OELFs are examined by the f-sum rule expected from the dielectric response theory, and by calculation of the mean excitation energy. The calculated SPs are compared with those for PMMA (polymethylmethacrylate, a tissue equivalent material) and liquid water. The SP and IMFP data presented here are the results for the 11 human tissues over the energy range of 20 eV-20 keV, and are of importance in radiotherapy planning and for studies of various radiation effects on human tissues.

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

    Indian Academy of Sciences (India)

    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.

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

    DEFF Research Database (Denmark)

    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...

  8. The Half Life of the 53 keV Level in {sup 197}Pt

    Energy Technology Data Exchange (ETDEWEB)

    Malmskog, S.G.

    1967-02-15

    The half life of the recently proposed 53 keV level in {sup 197}Pt has been measured to 18.5 {+-} 1.5 nsec using the delayed coincidence technique. This level, which is identified with the f{sub 5/2} single particle state, decays directly to the p{sub 1/2} ground state in {sup 197}Pt. The reduced E2 transition probability for this 53 keV transition has been deduced and compared with the results obtained for the corresponding transitions in other Pt, Hg, and Pb isotopes and with the theoretical predictions by Sorensen and by Wahlborn and Martinson.

  9. 3.55 keV line in minimal decaying dark matter scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Arcadi, Giorgio [Laboratoire de Physique Théorique, Université Paris-Sud,F-91405 Orsay (France); Covi, Laura; Dradi, Federico [Institute for Theoretical Physics, Georg-August University Göttingen,Friedrich-Hund-Platz 1, Göttingen, D-37077 (Germany)

    2015-07-20

    We investigate the possibility of reproducing the recently reported 3.55 keV line in some simple decaying dark matter scenarios. In all cases a keV scale decaying DM is coupled with a scalar field charged under SM gauge interactions and thus capable of pair production at the LHC. We will investigate how the demand of a DM lifetime compatible with the observed signal, combined with the requirement of the correct DM relic density through the freeze-in mechanism, impacts the prospects of observation at the LHC of the decays of the scalar field.

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

    Energy Technology Data Exchange (ETDEWEB)

    Aghai-Khozani, H. [Max-Planck-Institut fur Quantenoptik (Germany); Barna, D. [CERN (Switzerland); Corradini, M. [Università degli Studi di Brescia, Dipartimento di Ingegneria dell’Informazione (Italy); Salvador, D. De [Università di Padova, Dipartimento di Fisica e Astronomia (Italy); Hayano, R. [University of Tokyo, Department of Physics (Japan); Hori, M. [Max-Planck-Institut fur Quantenoptik (Germany); Kobayashi, T. [University of Tokyo, Department of Physics (Japan); Leali, M.; Lodi-Rizzini, E.; Mascagna, V. [Università degli Studi di Brescia, Dipartimento di Ingegneria dell’Informazione (Italy); Prest, M. [Università degli Studi dell’Insubria, Dipartimento di Scienza e Alta Tecnologia (Italy); Seiler, D. [TUM Department of Physics E12 (Germany); Soter, A. [Max-Planck-Institut fur Quantenoptik (Germany); Todoroki, K. [University of Tokyo, Department of Physics (Japan); Vallazza, E. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (Italy); Venturelli, L., E-mail: venturelli@bs.infn.it [Università degli Studi di Brescia, Dipartimento di Ingegneria dell’Informazione (Italy)

    2015-08-15

    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.

  11. Calibration of dosimeters at 80-120 keV electron irradiation

    DEFF Research Database (Denmark)

    Miller, A.; Helt-Hansen, J.

    We describe calorimeters for dose measurement at low-energy electron accelerator energies (80–120 keV). Three calorimeters with different characteristics were designed and their dose response and measurement uncertainties were characterized. The heatedair between the electron beam exit window...... to calibrate thin-film dosimeters (Risø B3 and alanine films) by irradiation at the 80–120 keV electron accelerators. This calibration was compared to a 10MeV calibration, and we show that the radiation response of the dosimeter materials (the radiation chemical yield) is constant at these irradiation energies...

  12. Echo 2 - Observations at Fort Churchill of a 4-keV peak in low-level electron precipitation

    Science.gov (United States)

    Arnoldy, R. L.; Hendrickson, R. A.; Winckler, J. R.

    1975-01-01

    The Echo 2 rocket flight launched from Fort Churchill, Manitoba, offered the opportunity to observe high-latitude low-level electron precipitation during quiet magnetic conditions. Although no visual aurora was evident at the time of the flight, an auroral spectrum sharply peaked at a few keV was observed to have intensities from 1 to 2 orders of magnitude lower than peaked spectra typically associated with bright auroral forms. There is a growing body of evidence that relates peaked electron spectra to discrete aurora. The Echo 2 observations show that whatever the mechanism for peaking the electron spectrum in and above discrete forms, it operates over a range of precipitation intensities covering nearly 3 orders of magnitude down to subvisual or near subvisual events.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  15. The C14(n,γ) cross section between 10 keV and 1 MeV

    Science.gov (United States)

    Reifarth, R.; Heil, M.; Forssén, C.; Besserer, U.; Couture, A.; Dababneh, S.; Dörr, L.; Görres, J.; Haight, R. C.; Käppeler, F.; Mengoni, A.; O'Brien, S.; Patronis, N.; Plag, R.; Rundberg, R. S.; Wiescher, M.; Wilhelmy, J. B.

    2008-01-01

    The neutron capture cross section of C14 is of relevance for several nucleosynthesis scenarios such as inhomogeneous Big Bang models, neutron induced CNO cycles, and neutrino driven wind models for the r process. The C14(n,γ) reaction is also important for the validation of the Coulomb dissociation method, where the (n,γ) cross section can be indirectly obtained via the time-reversed process. So far, the example of C14 is the only case with neutrons where both, direct measurement and indirect Coulomb dissociation, have been applied. Unfortunately, the interpretation is obscured by discrepancies between several experiments and theory. Therefore, we report on new direct measurements of the C14(n,γ) reaction with neutron energies ranging from 20 to 800 keV.

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

    Science.gov (United States)

    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.

  17. Multiple capture investigated by coincident electron spectroscopy in X{sup 7+}+Ar, at 70 keV

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Universite Paul Sabatier, Toulouse (France). Lab. Collisions-Agregats-Reactivite

    1999-11-01

    The multiple electron capture in N{sup 7+} + Ar and F{sup 7+}(1s{sup 2}) + Ar systems is investigated at 70 keV with a new electron-recoil ion charge coincidence experiment. The whole electron energy range has been studied. Up to six electrons are found to be captured into autoionizing states. The recoil ion charge distribution associated with the emission of electrons is similar for both systems and found to be in good agreement with the prediction of Niehaus`s model roughly adapted to take into account autoionizing cascades. New findings for the coincident double and triple captures are briefly discussed. A capture of an inner L-shell electron of Ar into the K-shell of the projectile is also observed in N{sup 7+} + Ar collisions. (orig.) 10 refs.

  18. Elastic and inelastic processes in He/sup +/-H/sub 2/ collisions between 2 and 30 keV

    Energy Technology Data Exchange (ETDEWEB)

    Bergnes, C.; Bordenave-Montesquieu, D.; Boutonnet, A.; Nouet, P.; Dagnac, R.

    1986-10-14

    The elastic and inelastic processes have been studied for scattering of He/sup +/ ions by H/sub 2/ molecules between 2 and 30 keV in the angular range from 10' to 3/sup 0/ by an energy loss technique. The analysis of elastic energy loss against E/sub 0/theta/sup 2/ shows that the incident ion is scattered by the entire molecule at low energies whereas at high energies it is scattered by only one atom in the target. Comparison of the relative probabilities of the various excitation processes with the isoelectronic system He/sup +/-He demonstrates the different behaviours of a molecular target in the excitation mechanism.

  19. Range Tracing

    OpenAIRE

    Jenke, Philipp; Huhle, Benjamin

    2010-01-01

    In this report, we tackle the problem of merging an arbitrary number of range scans (depth images) into a single surface mesh. The mesh-based representation is superior to point-based approaches since it contains important connectivity information. Most previous mesh-based merge methods, however, lose surface details by using simplifying intermediate surface representations (e.g.\\ implicit functions). Such details are essential for further processing steps, especially for feature-preserving r...

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  1. Amorphization of silicon by bombardment with oxygen ions of energy below 5 keV

    Energy Technology Data Exchange (ETDEWEB)

    Zhukovskii, P.V.; Stel' makh, V.F.; Tkachev, V.D.

    1977-04-01

    Silicon was bombarded with /sup 16/O/sup +/ ions of 1.0 and 3.0 keV energies at room temperature. This bombardment created point defects which joined up to form amorphous layers about 100 A thick. (AIP)

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

    CERN Document Server

    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...

  3. Response of low-noise miniaturized proportional counters in the keV region

    Science.gov (United States)

    Belli, P.; Cattadori, C.; Cerulli, R.; d'Angelo, S.; Ferrari, N.; Pandola, L.

    2005-04-01

    Miniaturized low-noise low-background proportional counters, used in the GNO experiment, have been calibrated in the keV energy region along their longitudinal axis by means of a new z- scanning system working deep underground at the Gran Sasso National Laboratory of the I.N.F.N.. Some of the obtained experimental features are reported.

  4. Dissociation of water molecules upon keV H+- and Heq+-induced ionization

    NARCIS (Netherlands)

    Alvarado, F; Hoekstra, R; Schlatholter, T

    2005-01-01

    The interaction of keV H+, He+ and He2+, ions with gas-phase H2O molecules leads to formation of H2Oq+ ions which subsequently can undergo dissociation into various fragment species. From coincident determination of the fragmention kinetic energies, kinetic energy releases (KER) for the different di

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

    CERN Document Server

    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.

  6. Transmission of 18 kev negative ions Cl- through nanocapillariesin Al2O3 membrane

    Institute of Scientific and Technical Information of China (English)

    Lü Xue-Yang; Yin Yong-Zhi; Wang Hong-Wei; Ji Ming-Chao; Chen Lin; Chen Xi-Meng; Jia Juan-Juan; Zhou Peng; Zhou Chun-Lin; Qiu Xi-Yu; Shao Jian-Xiong; Cui Ying

    2011-01-01

    We investigate the angular distribution of the transmitted 18kev negative ions Cl- through Al2O3 nanocapillaries of 50 nm in diameter and 10μm in length. Elastic scattering ions and inelastic scattering ions are obtained simultaneonsly. The experimental result is partially consistent with the guiding effect. We can qualitatively explain our experimental result through a dynamic process.

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

    DEFF Research Database (Denmark)

    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...

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

    DEFF Research Database (Denmark)

    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...

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

    CERN Document Server

    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.

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

    CERN Document Server

    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} %.

  11. Cascade Annealing of Tungsten Implanted with 5 keV Noble Gas Atoms : A Computer Simulation

    NARCIS (Netherlands)

    Kolk, G.J. van der; Veen, A. van; Caspers, L.M.; Hosson, J.Th.M. De

    1984-01-01

    The trapping of vacancies by implanted atoms is calculated. After low energy implantation (5 keV) of tungsten with heavy noble gas atoms most of the implanted atoms are in substitutional position with one or two vacancies closer than two lattice units. Under the influence of the lattice distortion a

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

    CERN Document Server

    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...

  13. Dynamical framework for KeV Dirac neutrino warm dark matter

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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. Sputtering and surface structure modification of gold thin films deposited onto silicon substrates under the impact of 20–160 keV Ar{sup +} ions

    Energy Technology Data Exchange (ETDEWEB)

    Mammeri, S., E-mail: smammeri@yahoo.fr [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-Gare, Algiers (Algeria); Ouichaoui, S. [Université des Sciences et de la Technologie H. Boumediene (USTHB), Faculté de Physique, Laboratoire SNIRM, B.P. 32, El-Alia, 16111 Bab Ezzouar, Algiers (Algeria); Ammi, H.; Dib, A. [Centre de Recherche Nucléaire d’Alger, B.P. 399, 02 Bd. Frantz Fanon, Alger-Gare, Algiers (Algeria)

    2014-10-15

    Highlights: •Sputter yields were measured for gold thin films under keV Ar{sup +} ion bombardment. •RBS analysis was used to derive energy dependence of sputtering yield. •Surface effects under Ar{sup +} ion irradiation were studied by SEM and XRD analyses. -- Abstract: The induced sputtering and surface state modification of Au thin films bombarded by swift Ar{sup +} ions under normal incident angle have been studied over an energy range of (20–160) keV using three complementary techniques: Rutherford backscattering spectroscopy (RBS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The sputtering yields determined by RBS measurements using a 2 MeV {sup 4}He{sup +} ion beam were found to be consistent with previous data measured within the Ar{sup +} ion energy region E ⩽ 50 keV, which are thus extended to higher bombarding energies. Besides, the SEM and XRD measurements clearly point out that the irradiated Au film surfaces undergo drastic modifications with increasing the Ar{sup +} ion energy, giving rise to the formation of increasingly sized grains of preferred (1 1 1) crystalline orientations. The relevance of different sputtering yield models for describing experimental data is discussed with invoking the observed surface effects induced by the Ar{sup +} ion irradiation.

  16. XMM-Newton observation of the Seyfert 1.8 ESO 113-G010: discovery of a highly redshifted iron line at 5.4 keV

    CERN Document Server

    Porquet, D; Uttley, P; Turner, T J

    2004-01-01

    We present a spectral analysis of the Seyfert 1.8 ESO 113-G010 observed with XMM-Newton for 4 ks. The spectrum shows a soft excess below 0.7 keV and more interestingly a narrow emission Gaussian line at 5.4 keV (in its rest-frame), most probably originating from a redshifted iron Kalpha line. No significant line at or above 6.4 keV is found contrary to other objects showing redshifted lines, ruling out a strong blue-wing to the line profile. The line is detected at 99% confidence, from performing Monte Carlo simulations which fully account for the range of energies where a narrow iron line is likely to occur. The energy of the line could indicate emission from relativistic (0.17 - 0.23 c) ejected matter moving away from the observer, as proposed for Mrk 766 by Turner et al. (2004). Alternatively, the emission from a narrow annulus at the surface of the accretion disk.

  17. L x-ray production cross sections in Th and U at 17.8, 25.8 and 46.9 keV photon energies

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ajay; Shahi, J.S.; Mehta, D.; Singh, Nirmal [Department of Physics, Panjab University, Chandigarh (India); Puri, Sanjiv [Department of Physics, SLIET, Longowal (India); Garg, M.L. [Department of Biophysics, Panjab University, Chandigarh (India)

    2001-02-28

    The L x-ray production (XRP) differential cross sections in Th and U have been measured at the 17.8 keV incident photon energy (E{sub L3}range 90 deg-160 deg, and at the 25.8 and 46.9 keV incident photon energies (E{sub L1}keV photon energies, deduced assuming isotropic emission of the L x-rays, are found to be in good agreement with those evaluated using the most reliable theoretical values of L{sub i} (i=1,2,3) subshell photoionization cross sections, fluorescence yields, x-ray emission rates and Coster-Kronig transition probabilities. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

  20. Dynamical simulations of radiation damage induced by 10 keV energetic recoils in UO 2

    Science.gov (United States)

    Tian, X. F.; Gao, T.; Long, Chongsheng; Li, JiuKai; Jiang, Gang; Xiao, Hongxing

    2011-08-01

    We have performed classical molecular dynamics simulations to simulate the primary damage state induced by 10 keV energetic recoils in UO 2. The numbers versus time and the distance distributions for the displaced uranium and oxygen atoms were investigated with the energetic recoils accelerated along four different directions. The simulations suggest that the direction of the primary knock-on atom (PKA) has no effect on the final primary damage state. In addition, it was found that atomic displacement events consisted of replacement collision sequences in addition to the production of Frenkel pairs. The spatial distribution of defects introduced by 10 keV collision cascades was also presented and the results were similar to that of energetic recoils with lower energy.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lakshmi, G.B.V.S., E-mail: lakshmigbvs@gmail.com [Inter University Accelerator Centre, New Delhi 67 (India); Avasthi, D.K. [Amity University, Noida 201313, Uttar Pradesh (India)

    2016-07-15

    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{sup +} 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.

  2. SMM detection of diffuse Galactic 511 keV annihilation radiation

    Science.gov (United States)

    Share, G. H.; Kinzer, R. L.; Kurfess, J. D.; Messina, D. C.; Purcell, W. R.

    1988-01-01

    Observations of the 511 keV annihilation line from the vicinity of the Galactic center from October to February for 1980/1981, 1981/1982, 1982/1983, 1984/1985, and 1985/1986 are presented. The measurements were made with the gamma-ray spectrometer on the SMM. The design of the instrument and some of its properties used in the analysis are described, and the methods used for accumulating, fitting, and analyzing the data are outlined. It is shown how the Galactic 511 keV line was separated from the intense and variable background observed in orbit. The SMM observations are compared with previous measurements of annihilation radiation from the Galactic center region, and the astrophysical implications are discussed. It is argued that most of the measurements made to date suggest the presence of an extended Galactic source of annihilation radiation.

  3. Production of Sterile Neutrino dark matter and the 3.5 keV line

    Energy Technology Data Exchange (ETDEWEB)

    Merle, Alexander, E-mail: amerle@mpp.mpg.de [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany); Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ (United Kingdom); Schneider, Aurel, E-mail: aurel@physik.uzh.ch [Institute for Computational Science, University of Zürich, Winterthurerstrasse 190, CH-8057, Zürich (Switzerland); Department of Physics & Astronomy, University of Sussex, Brighton, BN1 9QH (United Kingdom)

    2015-10-07

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, D. H.; Takman, P. A. C.; Lundstroem, U.; Burvall, A.; Hertz, H. M. [Biomedical and X-Ray Physics, Department of Applied Physics, Royal Institute of Technology/Albanova, SE-10691 Stockholm (Sweden)

    2011-12-15

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

  5. Charge transfer in keV O+(4S,2D,2P)-He collisions

    Science.gov (United States)

    Lindsay, B. G.; Stebbings, R. F.

    2003-02-01

    Absolute differential cross sections (DCSs) are reported for charge-transfer scattering of (1 5)-keV O+(4S) ground-state and O+(2D,2P) metastable-state ions by helium atoms at angles between 0.2° and 6.3° in the laboratory frame. Estimated ground-state and metastable-state total cross sections are derived from these measurements. The present ground-state cross sections agree satisfactorily with previous measurements for energies above 2 keV and the metastable-state cross sections are consistent with the mixed-state data of Kusakabe et al. [J. Phys. Soc. Japan 59, 1987 (1990)]. The large differences between the ground- and metastable-state cross sections predicted by theory are not observed.

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

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

    CERN Document Server

    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.

  8. keV sterile neutrino Dark Matter in gauge extensions of the Standard Model

    CERN Document Server

    Bezrukov, F; Lindner, M

    2009-01-01

    It is known, that a keV scale sterile neutrino is a good Warm Dark Matter (WDM) candidate. We study how this possibility could be realised in the context of gauge extensions of the Standard Model (SM). The naive expectation leads to large thermal overproduction of sterile neutrinos in this setup. However, we find that it is possible to use out-of-equilibrium decay of the other right-handed neutrinos of the model to dilute the present density of the keV sterile neutrinos and achieve the observed DM density. We present the universal requirements that should be satisfied by the gauge extensions of the SM, containing right-handed neutrinos, to be viable models of WDM, and provide a simple example in the context of the Left-Right symmetric model.

  9. PENETRATION DEPTH OF 0.5-3-KEV ELECTRONS IN SOLID HYDROGEN AND DEUTERIUM

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.

    1978-01-01

    The mirror-substrate method was used for measuring the penetration depth of 0. 5-3-keV electrons in solid hydrogen and deuterium. The penetration depth was found to be 0. 53 multiplied by 10**1**8E**1**. **7**2 molecules/cm**2 with the energy given in keV. There was satisfactory agreement...... with other data. The measurements also showed that the escape depth for true secondary electrons from solid deuterium is less than 50 A, which agrees well with the small values for the secondary-electron-emission coefficient found for solid deuterium. Results were furthermore obtained for the electron......-reflection coefficient for the gold substrate, i. e. , the number of electrons that are reflected with high energies. The electron-reflection coefficient agrees well with other results, both with respect to magnitude and energy dependence....

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

    DEFF Research Database (Denmark)

    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...... calculations. A thermal model was developed to estimate the temperature contributions from the air above the calorimeter that is heated by the electron beam. As an example, Riso B3 thin-film dosimeters were calibrated by 80-120 keV electron irradiation and compared with a calibration carried out at 10 Me......V electron irradiation. The two calibrations were found to be equal within the estimated uncertainties of +/-10% at 1 s.d. (C) 2004 Elsevier Ltd. All rights reserved....

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

    Science.gov (United States)

    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.

  12. Secondary emission monitor for keV ion and antiproton beams

    CERN Document Server

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  14. Coherent keV backscattering from plasma-wave boosted relativistic electron mirrors

    CERN Document Server

    Li, F Y; Chen, M; Wu, H C; Liu, Y; Meyer-ter-Vehn, J; Mori, W B; Zhang, J

    2014-01-01

    A new parameter regime of laser wakefield acceleration driven by sub-petawatt femotsecond lasers is proposed, which enables the generation of relativistic electron mirrors further accelerated by the plasma wave. Integrated particle-in-cell simulation including the mirror formation and Thomson scattering demonstrates that efficient coherent backscattering up to keV photon energy can be obtained with moderate driver laser intensities and high density gas targets.

  15. Hitomi Constraints on the 3.5 keV Line in the Perseus Galaxy Cluster

    Science.gov (United States)

    Aharonian, F. A.; Akamatsu, H.; Akimoto, F.; Allen, S. W.; Angelini, L.; Arnaud, K. A.; Audard, M.; Awaki, H.; Axelsson, M.; Bamba, A.; Bautz, M. W.; Blandford, R. D.; Bulbul, E.; Brenneman, L. W.; Brown, G. V.; Cackett, E. M.; Chernyakova, M.; Chiao, M. P.; Coppi, P.; Costantini, E.; de Plaa, J.; den Herder, J.-W.; Done, C.; Dotani, T.; Ebisawa, K.; Eckart, M. E.; Enoto, T.; Ezoe, Y.; Fabian, A. C.; Ferrigno, C.; Foster, A. R.; Fujimoto, R.; Fukazawa, Y.; Furuzawa, A.; Galeazzi, M.; Gallo, L. C.; Gandhi, P.; Giustini, M.; Goldwurm, A.; Gu, L.; Guainazzi, M.; Haba, Y.; Hagino, K.; Hamaguchi, K.; Harrus, I.; Hatsukade, I.; Hayashi, K.; Hayashi, T.; Hayashida, K.; Hiraga, J.; Hornschemeier, A. E.; Hoshino, A.; Hughes, J. P.; Ichinohe, Y.; Iizuka, R.; Inoue, H.; Inoue, S.; Inoue, Y.; Ishibashi, K.; Ishida, M.; Ishikawa, K.; Ishisaki, Y.; Itoh, M.; Iwai, M.; Iyomoto, N.; Kaastra, J. S.; Kallman, T.; Kamae, T.; Kara, E.; Kataoka, J.; Katsuda, S.; Katsuta, J.; Kawaharada, M.; Kawai, N.; Kelley, R. L.; Khangulyan, D.; Kilbourne, C. A.; King, A. L.; Kitaguchi, T.; Kitamoto, S.; Kitayama, T.; Kohmura, T.; Kokubun, M.; Koyama, S.; Koyama, K.; Kretschmar, P.; Krimm, H. A.; Kubota, A.; Kunieda, H.; Laurent, P.; Lebrun, F.; Lee, S.-H.; Leutenegger, M. A.; Limousin, O.; Loewenstein, M.; Long, K. S.; Lumb, D. H.; Madejski, G. M.; Maeda, Y.; Maier, D.; Makishima, K.; Markevitch, M.; Matsumoto, H.; Matsushita, K.; McCammon, D.; McNamara, B. R.; Mehdipour, M.; Miller, E. D.; Miller, J. M.; Mineshige, S.; Mitsuda, K.; Mitsuishi, I.; Miyazawa, T.; Mizuno, T.; Mori, H.; Mori, K.; Moseley, H.; Mukai, K.; Murakami, H.; Murakami, T.; Mushotzky, R. F.; Nakagawa, T.; Nakajima, H.; Nakamori, T.; Nakano, T.; Nakashima, S.; Nakazawa, K.; Nobukawa, K.; Nobukawa, M.; Noda, H.; Nomachi, M.; O’ Dell, S. L.; Odaka, H.; Ohashi, T.; Ohno, M.; Okajima, T.; Ota, N.; Ozaki, M.; Paerels, F.; Paltani, S.; Parmar, A.; Petre, R.; Pinto, C.; Pohl, M.; Porter, F. S.; Pottschmidt, K.; Ramsey, B. D.; Reynolds, C. S.; Russell, H. R.; Safi-Harb, S.; Saito, S.; Sakai, K.; Sameshima, H.; Sasaki, T.; Sato, G.; Sato, K.; Sato, R.; Sawada, M.; Schartel, N.; Serlemitsos, P. J.; Seta, H.; Shidatsu, M.; Simionescu, A.; Smith, R. K.; Soong, Y.; Stawarz, Ł.; Sugawara, Y.; Sugita, S.; Szymkowiak, A. E.; Tajima, H.; Takahashi, H.; Takahashi, T.; Takeda, S.; Takei, Y.; Tamagawa, T.; Tamura, K.; Tamura, T.; Tanaka, T.; Tanaka, Yasuo; Tanaka, Yasuyuki; Tashiro, M.; Tawara, Y.; Terada, Y.; Terashima, Y.; Tombesi, F.; Tomida, H.; Tsuboi, Y.; Tsujimoto, M.; Tsunemi, H.; Tsuru, T.; Uchida, H.; Uchiyama, H.; Uchiyama, Y.; Ueda, S.; Ueda, Y.; Ueno, S.; Uno, S.; Urry, C. M.; Ursino, E.; de Vries, C. P.; Watanabe, S.; Werner, N.; Wik, D. R.; Wilkins, D. R.; Williams, B. J.; Yamada, S.; Yamaguchi, H.; Yamaoka, K.; Yamasaki, N. Y.; Yamauchi, M.; Yamauchi, S.; Yaqoob, T.; Yatsu, Y.; Yonetoku, D.; Yoshida, A.; Zhuravleva, I.; Zoghbi, A.; Hitomi Collaboration

    2017-03-01

    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 high flux level. Taking into account the XMM measurement uncertainties for this region, the inconsistency with Hitomi is at a 99% significance for a broad dark matter line and at 99.7% for a narrow line from the gas. We do not find anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections. We do find a hint of a broad excess near the energies of high-n transitions of S xvi (E≃ 3.44 {keV} rest-frame)—a possible signature of charge exchange in the molecular nebula and another proposed explanation for the unidentified line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. A confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.

  16. The 511 keV emission from positron annihilation in the Galaxy

    Energy Technology Data Exchange (ETDEWEB)

    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.

  17. Ruling out the light WIMP explanation of the galactic 511 keV line

    CERN Document Server

    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.

  18. 1974 view into the cage of the 520 keV electrostatic preaccelerator of Linac 1

    CERN Multimedia

    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...

  19. Testing the Axion-Conversion Hypothesis of 3.5 keV Emission with Polarization

    Science.gov (United States)

    Gong, Yan; Chen, Xuelei; Feng, Hua

    2017-02-01

    The recently measured 3.5 keV line in a number of galaxy clusters, the Andromeda galaxy (M31), and the Milky Way (MW) center can be well accounted for by a scenario in which dark matter decays to axionlike particles (ALPs) and subsequently convert to 3.5 keV photons in magnetic fields of galaxy clusters or galaxies. We propose to test this hypothesis by performing x-ray polarization measurements. Since ALPs can only couple to photons with a polarization orientation parallel to the magnetic field, we can confirm or reject this model by measuring the polarization of the 3.5 keV line and compare it to the orientation of the magnetic field. We discuss luminosity and polarization measurements for both a galaxy cluster and spiral galaxy, and provide a general relation between the polarization and galaxy inclination angle. This effect is marginally detectable with x-ray polarimetry detectors currently under development, such as the enhanced X-ray Timing and Polarization satellite, the Imaging X-ray Polarimetry Explorer and the X-ray Imaging Polarimetry Explorer. The sensitivity can be further improved in the future with detectors of a larger effective area or better energy resolutions.

  20. Searching for keV Sterile Neutrino Dark Matter with X-ray Microcalorimeter Sounding Rockets

    CERN Document Server

    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.

  1. Laboratory measurements compellingly support a charge-exchange mechanism for the "Dark matter" ~3.5 keV X-ray line

    Science.gov (United States)

    Shah, Chintan; Bernitt, Sven; Dobrodey, Stepan; Steinbrügge, René; Gu, Liyi; Kaastra, Jelle S.; Crespo Lopez-Urrutia, José R.

    2017-08-01

    A mysterious X-ray signal at 3.5 keV from nearby galaxies and galaxy clusters recently sparked tremendous interest in the scientific community and has given rise to a tide of publications attempting to explain the origin of this line [1]. It has been hypothesized that the signal is the result of decaying sterile neutrinos - a potential dark matter particle candidate - presumably based on the fact that this X-ray line is not available in the standard spectral databases and models for thermal plasmas. Cautiously, Gu et al. [2] have pointed out an alternative explanation for this phenomenon: charge exchange between bare ions of sulfur and atomic hydrogen. Their model shows that X-rays should be emitted at 3.5 keV by a set of S15+ transitions from n ≥ 9 to the ground states, where n is the principle quantum number.We tested this hypothesis in the laboratory by measuring K-shell X-ray spectra of highly ionized sulfur ions following charge exchange with gaseous molecules in an electron beam ion trap. We produced bare S16+ and H-like S15+ ions and let them capture electrons in collisions with molecules while recording X-ray spectra. The 3.5 keV transition clearly shows up in the charge-exchange induced spectrum under a broad range of conditions. The inferred X-ray energy of 3.47 ± 0.06 keV is in full accord with both the astrophysical observations and theoretical calculations, and confirms the novel scenario proposed by Gu [2]. Taking the experimental uncertainties and inaccuracies of the astrophysical measurements into account, we conclude that the charge exchange between bare sulfur and hydrogen atoms can outstandingly explain the mysterious signal at around 3.5 keV [3].[1] E. Bulbul et al., Astrophys. J. 13, 789 (2014)[2] L. Gu et al., A & A L11, 584 (2015)[3] C. Shah et al., Astrophys. J. 833, 52 (2016)

  2. Properties of the Plasma Surrounding the Global Heliosphere Determined with Voyager 1&2 ions and ENA/INCA Observations at E > 5 keV

    Science.gov (United States)

    Krimigis, S. M.; Dialynas, K.; Mitchell, D. G.; Decker, R. B.; Roelof, E. C.

    2016-12-01

    The basic goal of the proposed Interstellar Mapping and Acceleration Probe (IMAP) is detailed scientific understanding of the Heliosheath (HS) and beyond, a region of space explored in situ by Voyager 1 (V1) since 2004, Voyager 2 (V2) since 2007, and remotely via energetic neutral atoms (ENA) by the Cassini/INCA (5.2-55 keV) since 2003 and IBEX (0.3-6 keV) since 2009. The partial overlap in energies (28 5 keV, the rest residing below that range, resulting in a beta (particle/magnetic pressure) always > 1, typically >10. (2) Based on the ENA-derived hot ion pressures, the interstellar magnetic field (ISMF) was predicted to be more than twice that expected in the literature i.e. similar to what was measured by V1 after crossing the heliopause (B 0.5 nT). (3) The width of the HS in the direction of V1 is 30 AU (predicted by INCA before the V1 HP crossing), but is thought to be larger (40-70 AU) in the southern ecliptic where V2, now 30 AU into the HS, currently travels. We address here the key question of the source of 5-55 keV ENAs that INCA measures. The analysis of INCA all-sky maps from 2003 to 2014 show that the decrease and recovery of ENA in the global heliosphere during this period (declining phase of SC23 and rise of SC24) is similar to that of the ions at V1/V2, consistent with the HS ions being the source of ENA. The close correspondence between ENA and ion spectra (despite the 140 AU distance between V1 and V2) as well as the similarity of ENA spectra over the nose and anti-nose directions, together with the recent V1 measurement of a BISMF 0.5nT, suggest that the global distributions of >5 keV ions in the heliosheath resembles a diamagnetic bubble with no significant tail-like feature (the alternative Parker 1961 model), also consistent with some recent MHD simulations and models.

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

    Energy Technology Data Exchange (ETDEWEB)

    Shafiei, S.; Lamehi-Rachti, M., E-mail: mlamehi@aeoi.org.ir

    2015-02-15

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

  4. X-ray reflectometer for single layer and multilayer coating characterization at 8 keV: An interlaboratory study

    Science.gov (United States)

    Gurgew, Danielle N.; Broadway, David M.; Gubarev, Mikhail; Ramsey, Brian D.; Gregory, Don A.

    2016-10-01

    An X-ray reflectometer (XRR) system has been developed at the Marshall Space Flight Center (MSFC) for characterizing various soft and hard X-ray optic coatings. The XRR instrument generates X-ray radiation using a high-output rotating anode source (RAS), operational over a voltage range of 5-35 kV and a current range of 10-150 mA. Copper is used as the target material to produce an X-ray spectrum from which the Kα line at 8.048 keV is isolated for the reflectivity measurements. Five precision slits are mounted along the X-ray beam path to limit the extent of the beam at the sample and to adjust the resolution in the measurements. A goniometer consisting of two precision rotary stages controls the positions of the coating sample and the X-ray detector with respect to the beam. The detector itself is a high performance silicon drift detector used to achieve high count rate efficiency to attain good statistics in the reflectivity measurement at larger grazing angles. The X-ray reflectometer system design and capabilities are described in detail. Verification of the system is obtained through an interlaboratory study in which reflectivity measurements of a multilayer coating made at MSFC are compared with those made at two external laboratories.

  5. 63Cu(n ,γ ) cross section measured via 25 keV activation and time of flight

    Science.gov (United States)

    Weigand, M.; Beinrucker, C.; Couture, A.; Fiebiger, S.; Fonseca, M.; Göbel, K.; Heftrich, M.; Heftrich, T.; Jandel, M.; Käppeler, F.; Krása, A.; Lederer, C.; Lee, H. Y.; Plag, R.; Plompen, A.; Reifarth, R.; Schmidt, S.; Sonnabend, K.; Ullmann, J. L.

    2017-01-01

    In the nuclear mass range A ≈60 to 90 of the solar abundance distribution the weak s -process component is the dominant contributor. In this scenario, which is related to massive stars, the overall neutron exposure is not sufficient for the s process to reach mass flow equilibrium. Hence, abundances and isotopic ratios are very sensitive to the neutron capture cross sections of single isotopes, and nucleosynthesis models need accurate experimental data. In this work we report on a new measurement of the 63Cu(n ,γ ) cross section for which the existing experimental data show large discrepancies. The 63Cu(n ,γ ) cross section at kBT =25 keV was determined via activation with a quasistellar neutron spectrum at the Joint Research Centre (JRC) in Geel, and the energy dependence was determined with the time-of-flight technique and the calorimetric 4 π BaF2 detector array DANCE at the Los Alamos National Laboratory. We provide new cross section data for the whole astrophysically relevant energy range.

  6. Properties of annealed Se/sup +/-implanted GaInAs. [400 keV Se/sup +/

    Energy Technology Data Exchange (ETDEWEB)

    Sealy, B.J.; Shahid, M.A.; Anjum, M. (Surrey Univ., Guildford (UK). Dept. of Electronic and Electrical Engineering); Gill, S.S. (Royal Signals and Radar Establishment, Malvern (UK)); Marsh, J.H. (Sheffield Univ. (UK). Dept. of Electronic and Electrical Engineering)

    1985-03-01

    p-GaInAs lattice matched to (100) InP was grown and implanted with selenium ions at room temperature. The dose was in the range of 5 x 10/sup 13/ to 5 x 10/sup 15/ ions cm/sup -2/ at an energy of 400 keV. The results of secondary ion mass spectroscopy indicate that for short anneals of 30 s at 800/sup 0/C, very little dopant redistribution takes place. However, for longer time anneals of 900 s at 800/sup 0/C a significant outdiffusion and loss of selenium is observed. Electron concentrations in the range of 10/sup 18/ to 10/sup 19/ cm/sup -3/ with corresponding Hall mobilities of 1800 to 1200 cm/sup 2/ V/sup -1/ s/sup -1/ were measured, the lowest sheet resistivity being 12 ..cap omega../square white. Transmission electron microscopy results indicate that good crystallinity in the implanted material is restored after short time anneals, but the long time anneals introduce damage within the implanted region.

  7. Hard X-ray detection of the black hole candidates 4U 1630-47 and IGR J17091-3624 up to 200 keV with INTEGRAL

    DEFF Research Database (Denmark)

    Bodaghee, A.; Kuulkers, E.; Tomsick, J. A.

    2012-01-01

    is statistically compatible with the source flux measured by Swift-BAT on that date in a similar energy range (28+/-4 mCrab: http://heasarc.nasa.gov/docs/swift/results/transients ). In JEM-X, 4U 1630-47 has count rates of 94.0+/-2.2 cts/s (534+/-13 mCrab, 43-sigmas) in the 3-10 keV band, and 6.4+/-0.9 cts/s (90...... is lower than the 24+/-5 mCrab measured by Swift-BAT on that date in the 15-50 keV band, while the hard-band flux is higher than the value in the same energy range during the previous outburst (20+/-3 mCrab: ATel #3916). This source was outside the field of view of JEM-X. The source spectrum can be fit...... with a power law (Gamma = 1.7+/-0.4; red. Chi^2/dof = 1.5/10; observed flux = 6e-10 erg/cm2/s in 20-100 keV) up to ~200 keV with no evidence for a cutoff. It was also detected above the 6-sigma level in both ISGRI bands during the previous observation of the field (rev. 1207). A possible transition to the hard...

  8. 宫颈液基薄层细胞学检测5100例的结果分析%Analysis of 5 100 cases of cervical liquid based cytology test results

    Institute of Scientific and Technical Information of China (English)

    刘斌; 李燕维

    2015-01-01

    目的:探讨宫颈液基薄层细胞学检测在妇女疾病普查中的意义.方法:收集5 100例宫颈液基薄层细胞学检测结果,均采用液基薄层细胞学检查系统制片,应用 TBS 系统进行分类及报告.结果:阳性检出率 6.51%;在 HSIL中,两者检测结果符合率 74.07%;在 LSIL 中,符合率 53.33%;在 ASCU-H 和 ASCUS 中,检出率 22.04%.结论:针对宫颈癌前病变筛查,液基薄层细胞学检测结果准确性高,但仍然存在一些假阳性与假阴性现象.%Objective:To investigate the significance of thin layer cytology test for cervical liquid based cytology in women. Methods:5 100 cases of cervical liquid based thin layer cytology test results were collected,and the TBS system was used to classify and report.Results:The positive detection rate was 6.51% ;in HSIL,the coincidence rate was 74.07% ;in LSIL,the coincidence rate was 53.33%,the detection rate was 22.04% in ASCUS and ASCU-H.Conclusion:For the screening of cervical precancerous lesions,the accuracy of liquid based cytology is high,but there are still some false positive and false negative.

  9. Correlation between electrical transport, microstructure and room temperature ferromagnetism in 200 keV Ni{sup 2+} ion implanted zinc oxide (ZnO) thin films

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  10. Validation of modelled imaging plates sensitivity to 1-100 keV x-rays and spatial resolution characterisation for diagnostics for the "PETawatt Aquitaine Laser".

    Science.gov (United States)

    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.

  11. Radiation-induced effects in MgO single crystal by 200 keV and 1 MeV Ni ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    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)

  12. The 2-10 keV X-Ray Background Dipole and Its Cosmological Implications

    Science.gov (United States)

    Scharf, C. A.; Jahoda, K.; Treyer, M.; Lahav, O.; Boldt, E.; Piran, T.

    2000-11-01

    The hard X-ray (>2 keV) emission of the local and distant universe as observed with the HEAO 1 A-2 experiment is reconsidered in the context of large-scale cosmic structure. Using all-sky X-ray samples of active galactic nuclei (AGNs) and galaxy clusters, we remove the dominant local X-ray flux from within a redshift of ~0.02. We evaluate the dipolar and higher order harmonic structure in four X-ray colors. The estimated dipole anisotropy of the unresolved flux appears to be consistent with a combination of the Compton-Getting effect due to the Local Group motion (dipole amplitude Δ=0.0042) and remaining large-scale structure (0.00232 keV Galactic X-ray emission. Comparison of the soft and hard color maps with a harmonic analysis of the 1.5 keV ROSAT all-sky data qualitatively suggests that at least a third of the faint, unresolved ~18° scale structure in the HEAO 1 A-2 data may be Galactic in origin. However, the effect on measured flux dipoles is small (frame can constrain the amplitude of bulk motions of the universe. From observed bulk motions over a local ~50 h-1 Mpc radius volume, we determine 0.14<~Ω0.60/bX(0)<~0.59, where Ω0 is the universal density parameter and bX(0) is the present-epoch bias parameter, defined as the ratio of fluctuations in the X-ray source density and the mass density.

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

    Science.gov (United States)

    Conlon, Joseph P; Marsh, M C David

    2013-10-11

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

  14. X-ray imaging microscopy at 25 keV with Fresnel zone plate optics

    CERN Document Server

    Awaji, M; Takeuchi, A; Takano, H; Kamijo, N; Tamura, S; Yasumoto, M

    2001-01-01

    X-ray imaging microscopy with a sputtered-sliced Fresnel zone plate (SS-FZP) has been developed at an X-ray energy of 25 keV. Objects were imaged in transmission with the SS-FZP as an objective with a magnification of 10.2 times, and detected with a X-ray image sensor. The performance of the imaging microscope has been tested with a gold mesh and a resolution test pattern at an undulator beamline 47XU of SPring-8. The resolution test patterns up to 0.5 mu m line-and-space structures have been resolved.

  15. Neutron activation of natural zinc samples at kT = 25 keV

    OpenAIRE

    Reifarth, R.; Dababneh, S.; Heil, M.; Käppeler, F.; Plag, R.; Sonnabend, K.; Uberseder, E.

    2013-01-01

    The neutron-capture cross sections of 64Zn, 68Zn, and 70Zn have been measured with the activation technique in a quasistellar neutron spectrum corresponding to a thermal energy of kT = 25 keV. By a series of repeated irradiations with different experimental conditions, an uncertainty of 3% could be achieved for the 64Zn(n,g)65Zn cross section and for the partial cross section 68Zn(n,g)69Zn-m feeding the isomeric state in 69Zn. For the partial cross sections 70Zn(n,g)71Zn-m and 70Zn(n,g)71Zn-g...

  16. Subsurface and interface channeling of keV ions in graphene/SiC

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    DEFF Research Database (Denmark)

    Helt-Hansen, J.; Miller, A.; Sharpe, P.

    2005-01-01

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

  18. A 17 keV neutrino and large magnetic moment solution of the solar neutrino puzzle

    Science.gov (United States)

    Akhmedov, E. Kh.; Senjanovic, G.; Tao, Zhijian; Berezhiani, Z. G.

    1992-08-01

    Zee-type models with Majorons naturally incorporate the 17 keV neutrino but in their minimal version fail to simultaneously solve the solar neutrino puzzle. If there is a sterile neutrino state, a particularly simple solution is found to the solar neutrino problem, which besides nu(sub 17) predicts a light Zeldovich-Konopinski-Mahmoud neutrino nu(sub light) = nu(sub e) + nu(sub mu)(sup c) with a magnetic moment being easily as large as 10(exp -11)(mu)(sub B) through the Barr-Freire-Zee mechanism.

  19. 17 keV neutrino and large magnetic moment solution of the solar neutrino puzzle

    Science.gov (United States)

    Akhmedov, Eugeni Kh.; Berezhiani, Zurab G.; Senjanović, Goran; Tao, Zhijian

    1993-01-01

    Zee-type models with majorons naturally incorporate the 17 keV neutrino but in their minimal version fail to simultaneously solve the solar neutrino puzzle. If there is a sterile neutrino state, we find a particularly simple solution to the solar neutrino problem, which besides ν17 predicts a light Zeldovich-Konopinski-Mahmoud neutrino νlight = νe + νcμ with a magnetic moment being easily as large as 10 -11μB through the Barr-Freire-Zee mechanism.

  20. First Double Excitation Cross Sections of Helium Measured for 100-keV Proton Impact

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Laboratoire Collisions, Agregats, Reactivite, IRSAMC, UMR 5589, CNRS and Universite Paul Sabatier, 31062 Toulouse Cedex (France); Godunov, A.L.; Schipakov, V.A. [Troitsk Institute for Innovation and Fusion Research, Troitsk, Moscow region, 142092 (Russia)

    1997-12-01

    Excitation cross sections of the (2s{sup 2}){sup 1}S, (2p{sup 2}){sup 1}D , and (2s2p){sup 1}P autoionizing states of helium, produced in collisions with 100-keV protons, have been measured for the first time. Using a high resolution electron spectroscopy together with a recently proposed parametrization of autoionizing resonances distorted by Coulomb interaction in the final state makes it possible to extract from electron spectra {ital total cross sections} as well as {ital magnetic sublevel populations.} These new experimental data are briefly compared with out theoretical calculations. {copyright} {ital 1997} {ital The American Physical Society}

  1. Kinetic energy releases of small amino acids upon interaction with keV ions

    Energy Technology Data Exchange (ETDEWEB)

    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)

  2. Kinetic energy releases of small amino acids upon interaction with keV ions

    Science.gov (United States)

    Bari, S.; Alvarado, F.; Postma, J.; Sobocinski, P.; Hoekstra, R.; Schlathölter, T.

    2009-01-01

    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.

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

    CERN Document Server

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

    2012-01-01

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

  4. Design of reduced size long counter with flat response function from few keV to 20 MeV

    Directory of Open Access Journals (Sweden)

    Mazunga Mohamed

    2016-01-01

    Full Text Available In this study, a reduced size neutron long counter with improved response function was designed using SuperMC simulation code. The main parts of the reduced size long counter are 3He proportional counter, cylindrical moderators made of polyethylene, chromium metal converter, neutron absorber material and outer aluminum cover. A 1.5 cm thick layer of chromium metal was embedded into the hydrogen-rich moderator to enhance response of the long counter at high neutron energies. The radius and length of the long counter was reduced to 15 cm and 35 cm, respectively. In this design we managed to obtain a flat response function from a few keV to 20 MeV energy range. The angular response function, determined at 0.5 MeV and 14 MeV neutron energies, confirmed that the reduced size long counter designed in this study is not significantly affected by in-scattered neutrons. The reduced size long counter is suitable for use as a standard transfer instrument for monitoring neutron fluence in mono-energetic neutron fields.

  5. TEC evidence for near-equatorial energy deposition by 30-keV electrons in the topside ionosphere

    CERN Document Server

    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...

  6. Areal density effects on the blocking of 3-keV Ne7+ ions guided through nanocapillaries in polymers

    Science.gov (United States)

    Stolterfoht, N.; Hellhammer, R.; Sulik, B.; Juhász, Z.; Bayer, V.; Trautmann, C.; Bodewits, E.; Reitsma, G.; Hoekstra, R.

    2013-09-01

    We studied blocking effects on ion guiding through nanocapillaries in highly insulating polyethylene terephthalate (PET). The experiments were initiated in view of a previous study with capillaries in polycarbonate (PC) for which strong blocking effects were observed, whereas for PET these effects could not be detected. The aim was to find out whether the different results are caused by differences in the PET and PC materials or by differences in the areal densities of the capillaries. Transmission experiments of 3-keV Ne7+ ions were performed for a variety of PET samples with an areal capillary density ranging from 3 to 60×106 cm-2. The tilt angles were close to zero degree because previous blocking effects were found to be largest at small angles. Our results clearly show that blocking effects also exist for PET and that they are sensitively dependent on the areal capillary density, i.e., the mean capillary distance. The potential produced by the charges accumulated in neighboring capillaries is calculated showing that it plays an important role in the ion blocking. In addition, model calculations are performed providing expressions to determine the direct ion transmission for small tilt angles and divergent ion beams.

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

    Energy Technology Data Exchange (ETDEWEB)

    Gafton, E.V., E-mail: elena.gafton@insp.jussieu.fr [Alexandru Ioan Cuza University, Faculty of Physics, 11 Carol I Blv., Iasi 700506 (Romania); Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Bulai, G., E-mail: georgiana.bulai@yahoo.com [Alexandru Ioan Cuza University, Faculty of Physics, 11 Carol I Blv., Iasi 700506 (Romania); Caltun, O.F., E-mail: caltun@uaic.ro [Alexandru Ioan Cuza University, Faculty of Physics, 11 Carol I Blv., Iasi 700506 (Romania); Cervera, S., E-mail: sophie.cervera@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Macé, S., E-mail: stephane.mace@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Trassinelli, M., E-mail: martino.trassinelli@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Steydli, S., E-mail: sebastien.steydli@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France); Vernhet, D., E-mail: dominique.vernhet@insp.jussieu.fr [Institut des NanoSciences de Paris, CNRS-UMR 7588, Sorbonne Universités, UPMC Univ Paris 06, 75005 Paris (France)

    2016-08-30

    Highlights: • Effect of different ion beam fluences on zinc ferrite thin films structure was investigated. • First reported results on zinc ferrite thin films irradiated with slow highly charged ions. • Increased magnetization was observed for samples irradiated even at low fluence. • Measurements of blocking temperature of thin films before and after irradiation. - Abstract: 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 Ne{sup q+} ion irradiation and exhibit different behaviours depending on the ion fluence range.

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

    Science.gov (United States)

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

    2015-07-01

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

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

    Science.gov (United States)

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

    2015-07-08

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

  10. XMM-Newton observation of the Seyfert 1.8 ESO 113-G010: Discovery of a highly redshifted iron line at 5.4 keV

    Science.gov (United States)

    Porquet, D.; Reeves, J. N.; Uttley, P.; Turner, T. J.

    2004-11-01

    We present a spectral analysis of the Seyfert 1.8 ESO 113-G010 observed with XMM-Newton for 4 ks. The spectrum shows a soft excess below 0.7 keV and more interestingly a narrow emission Gaussian line at 5.4 keV (in its rest-frame), most probably originating from a redshifted iron Kα line. No significant line at or above 6.4 keV is found contrary to other objects showing redshifted lines, ruling out a strong blue-wing to the line profile. The line is detected at 99% confidence, from performing Monte Carlo simulations which fully account for the range of energies where a narrow iron line is likely to occur. The energy of the line could indicate emission from relativistic (0.17-0.23 c) ejected matter moving away from the observer, as proposed for Mrk 766 by Turner et al. (\\cite{Tu04}, ApJ, 603, 62). Alternatively, the emission from a narrow annulus at the surface of the accretion disk is unlikely due to the very small inclination angle (i.e. less than 10°) required to explain the narrow, redshifted line in this intermediate Seyfert galaxy. However emission from a small, localized hot-spot on the disk, occurring within a fraction of a complete disk orbit, could also explain the redshifted line. This scenario would be directly testable in a longer observation, as one would see significant variations in the energy and intensity of the line within an orbital timescale.

  11. Origin of the 6.4-keV line of the Galactic Ridge X-ray Emission

    CERN Document Server

    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...

  12. /sup 165/Ho(n,. gamma. ) standard cross section from 3 to 450 keV

    Energy Technology Data Exchange (ETDEWEB)

    Macklin, R.L.

    1976-03-01

    The /sup 165/Ho(n, ..gamma..) cross section was measured at the Oak Ridge Electron Linear Accelerator neutron time-of-flight facility. Nonhydrogenous scintillation detectors were used with pulse-height weighting to measure the prompt photon yield, normalized to the saturated 3.92-eV resonance in (/sup 165/Ho + n) and the shape of the /sup 6/Li(n,..cap alpha..) cross section. Resonance parameters for many of the observed peaks below 3 keV were determined by a nonlinear least-squares fit. The data to 100 keV were well fitted with energy-independent strength functions 10/sup 4/S/sup 0/ = 1.33 +- 0.14, 10/sup 4/S/sup 1/ = 1.36 +- 0.24, 10/sup 4/S/sub 2/ = 1.19 +- 0.76 and anti GAMMA/sub ..gamma../D/sub 0/ = 0.076/(3.23 +- 0.55 eV). The fluctuations of the cross section about the strength function fit are analyzed for 250-eV averages. The Wald-Wolfowitz ''Runs'' test is consistent with no additional nonrandom structure in the cross section. 3 figures, 1 table. (auth)

  13. The X-Ray Line Feature At 3.5 Kev In Galaxy Cluster Spectra

    CERN Document Server

    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...

  14. Stimulated Raman scattering in hydrogen by ultrashort laser pulse in the keV regime

    Science.gov (United States)

    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.

  15. Hitomi constraints on the 3.5 keV line in the Perseus galaxy cluster

    CERN Document Server

    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...

  16. View into the cage of the 520 keV preaccelerator of the PS Linac 1

    CERN Multimedia

    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...

  17. The Disturbed 17 keV Cluster Associated with the Radio Galaxy 3C 438

    CERN Document Server

    Kraft, R P; Hardcastle, M J; Jones, C; Nulsen, P E J

    2007-01-01

    We present results from a {\\em Chandra} observation of the cluster gas associated with the FR II radio galaxy 3C 438. This radio galaxy is embedded within a massive cluster with gas temperature $\\sim$17 keV and bolometric luminosity of 6$\\times10^{45}$ ergs s$^{-1}$. It is unclear if this high temperature represents the gravitational mass of the cluster, or if this is an already high ($\\sim$ 11 keV) temperature cluster that has been heated transiently. We detect a surface brightness discontinuity in the gas that extends $\\sim$600 kpc through the cluster. The radio galaxy 3C 438 is too small ($\\sim$110 kpc across) and too weak to have created this large disturbance in the gas. The discontinuity must be the result of either an extremely powerful nuclear outburst or the major merger of two massive clusters. If the observed features are the result of a nuclear outburst, it must be from an earlier epoch of unusually energetic nuclear activity. However, the energy required ($\\sim10^{63}$ ergs) to move the gas on th...

  18. Neutron activation of natural zinc samples at kT = 25 keV

    CERN Document Server

    Reifarth, R; Heil, M; Käppeler, F; Plag, R; Sonnabend, K; Uberseder, E

    2013-01-01

    The neutron-capture cross sections of 64Zn, 68Zn, and 70Zn have been measured with the activation technique in a quasistellar neutron spectrum corresponding to a thermal energy of kT = 25 keV. By a series of repeated irradiations with different experimental conditions, an uncertainty of 3% could be achieved for the 64Zn(n,g)65Zn cross section and for the partial cross section 68Zn(n,g)69Zn-m feeding the isomeric state in 69Zn. For the partial cross sections 70Zn(n,g)71Zn-m and 70Zn(n,g)71Zn-g, which had not been measured so far, uncertainties of only 16% and 6% could be reached because of limited counting statistics and decay intensities. Compared to previous measurements on 64,68Zn, the uncertainties could be significantly improved, while the 70Zn cross section was found to be two times smaller than existing model calculations. From these results Maxwellian average cross sections were determined between 5 and 100 keV. Additionally, the beta-decay half-life of 71Zn-m could be determined with significantly imp...

  19. Damage analysis of benzene induced by keV fullerene bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Czerwinski, B. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland)], E-mail: bartlomiej.czerwinski@uj.edu.pl; Rzeznik, L.; Paruch, R. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Garrison, B.J. [Department of Chemistry, Pennsylvania State University, University Park, PA 16802 (United States); Postawa, Z. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland)

    2009-05-01

    Molecular dynamics computer simulations have been used to investigate the damage of a benzene crystal induced by 5 keV C{sub 20}, C{sub 60}, C{sub 120} and C{sub 180} fullerene bombardment. The sputtering yield, the mass distributions, and the depth distributions of ejected organic molecules are analyzed as a function of the size of the projectile. The results indicate that all impinging clusters lead to the creation of almost hemispherical craters, and the process of crater formation only slightly depends on the size of the fullerene projectile. The total sputtering yield as well as the efficiency of molecular fragmentation are the largest for 5 keV C{sub 20}, and decrease with the size of the projectile. Most of the molecules damaged by the projectile impact are ejected into the vacuum during cluster irradiation. Similar behavior does not occur during atomic bombardment where a large portion of fragmented benzene molecules remain inside the crystal after projectile impact. This 'cleaning up' effect may explain why secondary ion mass spectrometry (SIMS) analysis of some organic samples with cluster projectiles can produce significantly less accumulated damage compared to analysis performed with atomic ion beams.

  20. Inelastic scattering of 59.5 keV photons by elements with 13{<=}Z{<=}82

    Energy Technology Data Exchange (ETDEWEB)

    Shahi, J.S.; Kumar, Ajay; Mehta, D.; Puri, Sanjiv; Garg, M.L.; Singh, Nirmal E-mail: nsingh@panjabuniv.chd.nic.in

    2001-06-01

    Inelastic scattering differential cross-sections for 59.5 keV photons at an angle of 121 deg.have been measured in 18 elements with 13{<=}Z{<=}82. The measurements were performed using an annular source of {sup 241}Am radioisotope as photon source and a planar Si(Li) detector. The measurements were performed under vacuum {approx}10{sup -2} Torr. The contribution due to photons scattered from the surroundings was minimized by placing the target and annular source assembly in a Pb housing, and using a vacuum chamber made of glass lined inside with Pb. Thin targets have been used to minimize the contribution of multiple scattered photons to the inelastic scattered peak. The product of the intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K X-ray yields from targets of different elements with 30{<=}Z{<=}69 excited by the 59.5 keV photons from {sup 241}Am source and from the knowledge of K X-ray fluorescence cross-sections. A calibrated {sup 241}Am radioactive point source was also used for this purpose. The measured inelastic scattering cross-sections are found to be in good agreement with those calculated using the Klein-Nishina cross-section for Compton scattering by stationary free electrons and the nonrelativistic Hartree-Fock incoherent scattering function S(x,Z)

  1. Status report on a dc 130-mA, 75-keV proton injector

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, J.; Arvin, A.; Hodgkins, D. [and others

    1997-10-01

    A 110-mA, 75-keV dc proton injector is being developed at Los Alamos. We use a microwave proton source coupled to a two solenoid, space-charge neutralized, low-energy beam transport (LEBT) system. The ion source produces 110-mA proton current at 75 keV using 600 - 800 W of 2.45 GHz input discharge power. Typical proton fraction is 85-90% of the total extracted ion current, and the rms normalized beam emittance after transport through a prototype 2.1 m LEBT is 0.20 ({pi}mm-mrad). Beam space-charge neutralization is measured to be > 98% which enables the solenoid magnetic transport to successfully match the injector beam into a radio-frequency quadrupole (RFQ). Beam simulations indicate small emittance growth in the proposed 2.8 m low-energy demonstration accelerator (LEDA) LEBT. The LEBT also contains beam diagnostics, steering, and a beam deflector for variable duty factor and accelerator fast protect functions. The injector computer controls and reliability status are also discussed.

  2. 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

    CERN Document Server

    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.

  3. Measurement of the 10B(p ,α0)7Be cross section from 5 keV to 1.5 MeV in a single experiment using the Trojan horse method

    Science.gov (United States)

    Spitaleri, C.; Puglia, S. M. R.; La Cognata, M.; Lamia, L.; Cherubini, S.; Cvetinović, A.; D'Agata, G.; Gulino, M.; Guardo, G. L.; Indelicato, I.; Pizzone, R. G.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Spartá, R.; Tudisco, S.; Tumino, A.; Del Santo, M. Gimenez; Carlin, N.; Munhoz, M. G.; Souza, F. A.; de Toledo, A. Szanto; Mukhamedzhanov, A.; Broggini, C.; Caciolli, A.; Depalo, R.; Menegazzo, R.; Rigato, V.; Lombardo, I.; Dell'Aquila, D.

    2017-03-01

    For the first time the astrophysical factor of the 10B(p ,α0)7Be reaction has been measured over a wide energy range, from 5 keV to 1.5 MeV, via the Trojan horse method (THM) applied to the quasifree 2H(10B,α 7Be)n reaction. Therefore, the S (E ) factor has been recast into absolute units by scaling in the energy range 200 keV-1.2 MeV to a recent measurement using the activation method, leading to a normalization uncertainty of 4 % . An R -matrix fit of the THM data was performed, to parametrize the S factor, obtain spectroscopic information on the populated resonances, and compare with other recent experiments. Finally, a new determination of the screening potential Ue has been obtained, Ue=240 ±50 eV, with a much smaller error than our previous measurement.

  4. Modelling of the implantation and the annealing stages of 800 keV {sup 3}He implanted tungsten: Formation of nanovoids in the near surface region

    Energy Technology Data Exchange (ETDEWEB)

    De Backer, A., E-mail: andree.de-backer@univ-lille1.fr [Unite Materiaux Et Transformations, UMET, UMR 8207, Universite de Lille 1, F-59655 Villeneuve d' Ascq (France); Laboratoire commun EDF-CNRS Etude et Modelisation des Microstructures pour le Vieillissement des Materiaux (EM2VM) (France); Lhuillier, P.E. [CNRS, UPR3079 CEMHTI, 1D Avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Universite d' Orleans, Faculte des Sciences, Avenue du Parc Floral, BP 6749, 45067 Orleans cedex 2 (France); Becquart, C.S. [Unite Materiaux Et Transformations, UMET, UMR 8207, Universite de Lille 1, F-59655 Villeneuve d' Ascq (France); Laboratoire commun EDF-CNRS Etude et Modelisation des Microstructures pour le Vieillissement des Materiaux (EM2VM) (France); Barthe, M.F. [CNRS, UPR3079 CEMHTI, 1D Avenue de la Recherche Scientifique, 45071 Orleans cedex 2 (France); Universite d' Orleans, Faculte des Sciences, Avenue du Parc Floral, BP 6749, 45067 Orleans cedex 2 (France)

    2012-10-15

    The formation of voids in tungsten implanted at room temperature with 800 keV {sup 3}He 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 10{sup 17} to 5 Multiplication-Sign 10{sup 20} ions m{sup -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.

  5. Energy and angular distributions of backscattered electrons from collisions of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets

    Indian Academy of Sciences (India)

    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.

  6. 60 keV Ar{sup +}-ion induced pattern formation on Si surface: Roles of sputter erosion and atomic redistribution

    Energy Technology Data Exchange (ETDEWEB)

    Garg, S.K., E-mail: sandeep@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Datta, D.P.; Kumar, M. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Som, T., E-mail: tsom@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

    2014-08-15

    Highlights: • AFM study of morphological evolution on Si surface under 60 keV Ar{sup +} ions irradiation as a function of angle of incidence and fluence. • Construction of parametric phase diagram of medium energy ion induced ripple formation on Si. • Observation of sticking similarities between medium and low energy ion-induced pattern. • Numerical estimation shows that simultaneous contribution of curvature dependent sputtering and ion induced atomic redistribution. - Abstract: We study the evolution of surface morphology on Si(1 0 0) surface due to 60 keV Ar{sup +}-ion irradiation at room temperature for a wide range of ion fluences (2–80 × 10{sup 17} ions cm{sup −2}) and angles of incidence (0°–75°). We have clearly distinguished linear and nonlinear regimes for the observed ripple patterns in our experiment. From our experimental results and those available in the literature, we have created a parametric phase diagram which summarizes an overview of pattern formation on silicon surface under medium energy ion irradiation. On the basis of this phase diagram, we demonstrate some striking similarities between medium and low energy ion-induced ripple patterns and infer that similar mechanisms may be responsible for pattern formation at both regimes. Comparison of our experimental results with numerical estimations reveals that both curvature dependent sputter erosion and ion induced atomic redistribution are responsible for the observed evolution of surface morphology.

  7. Analysis of sub-1 keV implants in silicon using SIMS, SRP, MEISS and DLTS: The xRLEAP low energy, high current implanter evaluated

    Energy Technology Data Exchange (ETDEWEB)

    Foad, M.A.; England, J.G.; Moffatt, S. [Applied Materials Implant Division, West Sussex (United Kingdom); Armour, D.G. [Univ. of Salford (United Kingdom)

    1996-12-31

    Ultra shallow junctions can be formed, amongst other techniques, by very low energy ion implantation. The Implant Division of Applied Materials have recently developed a low energy, high current ion implanter, the xRLEAP (xR family, Low Energy Advance Process). This implanter is capable of delivering product worthy beam currents, in the milli-ampere regime down to energies of few hundred electron volts. A series of B and BF{sub 2} implants were carried out onto non-amorphised, 200mm Si wafers using beam energies in the range 0.2keV < E < 1keV. As-implanted and annealed samples were profiled using Secondary Ion Mass Spectrometry (SIMS). Surface damage due to implantation was evaluated using Medium Energy Ion Scattering Spectroscopy (MEISS). The carrier concentration profiles and junction depths of the annealed samples were investigated using Spreading Resistance Probe (SRP). Samples with ultra shallow junctions, < 0.07{mu}m, were examined using Deep Level Transient Spectroscopy (DLTS) for the first time.

  8. Optical constants in the hard X-ray/Soft gamma ray range of selected materials for multilayer reflectors

    DEFF Research Database (Denmark)

    Cooper-Jensen, Carsten P.; Romaine, S.; Bruni, R.

    2007-01-01

    Future Astrophysics missions operating in the hard X-ray/Soft Gamma ray range is slated to carry novel focusing telescopes based on the use of depth graded multilayer reflectors. Current design studies show that, at the foreseen focal lengths, it should be feasible to focus X-rays at energies...... as high as 300 keV. These designs use extrapolations of theoretical and experimentally determined optical constants from below 200 keV. In this paper we report on the first experimental determination of optical constants up to and above 200 keV. We present these first results as obtained at the National...

  9. Intermediate structure in the keV fission cross section of /sup 235/U

    Energy Technology Data Exchange (ETDEWEB)

    Migneco, E. (Univ., Catania, Italy); Bonsignore, P.; Lanzano, G.; Wartena, J.A.; Weigmann, H.

    1975-10-01

    The relative fission cross section of /sup 235/U has been measured up to 200 keV with a nominal resolution of 1.0 ns/m, using a thin foil plastic scintillator detector. The data have been analyzed in order to detect nonstatistical effects due to intermediate structure. Statistical tests which have been applied to this fission and similar total cross section data include calculations of the auto-correlation function and Wald-Wolfowitz tests on the cross section and on the autocorrelograms. The comparison of the results indicates the presence of intermediate structure effects in fission cross-section which may be interpreted on the basis of the double-humped deformation potential. 5 figures. (auth)

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

    Science.gov (United States)

    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 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.

  11. First experimental detection of antiproton in-flight annihilation on nuclei at 130 keV

    CERN Document Server

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

    2012-01-01

    The existing data of antinucleon-nucleon and antinucleon-nuclei annihilation cross-sections are confined to energies above about 1MeV. Experimental limitations have prevented till now the lower energies data to be achieved in spite of the interest they represent for theoretical models. One of the unresolved question concerns the antiproton annihilation cross-section measured at LEAR on light nuclei in the MeV region, which show a saturation with the mass number of the target nucleus against any naive expectation. With regard to fundamental cosmology, the knowledge of the annihilation cross-sections at energies below 1MeV can contribute to understand the matter-antimatter asymmetry in the Universe. We present here the experimental demonstration of the feasibility of the measurement of antiproton-nuclei annihilation cross-sections in the 100 keV region.

  12. Absolute Transition Probabilities from the 453.1 keV Level in {sup 183}W

    Energy Technology Data Exchange (ETDEWEB)

    Malmskog, S.G.

    1966-10-15

    The half life of the 453.1 keV level in {sup 183}W 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, {delta}K = 2 transition rates to the 1/2{sup -} (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.

  13. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    Science.gov (United States)

    Naqvi, A. A.; Al-Matouq, Faris A.; Khiari, F. Z.; Gondal, M. A.; Rehman, Khateeb-ur; Isab, A. A.; Raashid, M.; Dastageer, M. A.

    2013-11-01

    Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53-3.68, 4.51, 5.27-5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

  14. Active detection of shielded SNM with 60-keV neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Hagmann, C; Dietrich, D; Hall, J; Kerr, P; Nakae, L; Newby, R; Rowland, M; Snyderman, N; Stoeffl, W

    2008-07-08

    Fissile materials, e.g. {sup 235}U and {sup 239}Pu, can be detected non-invasively by active neutron interrogation. A unique characteristic of fissile material exposed to neutrons is the prompt emission of high-energy (fast) fission neutrons. One promising mode of operation subjects the object to a beam of medium-energy (epithermal) neutrons, generated by a proton beam impinging on a Li target. The emergence of fast secondary neutrons then clearly indicates the presence of fissile material. Our interrogation system comprises a low-dose 60-keV neutron generator (5 x 10{sup 6}/s), and a 1 m{sup 2} array of scintillators for fast neutron detection. Preliminary experimental results demonstrate the detectability of small quantities (370 g) of HEU shielded by steel (200 g/cm{sup 2}) or plywood (30 g/cm{sup 2}), with a typical measurement time of 1 min.

  15. Recent Updates on the Searches for the 3.55 keV Line

    Science.gov (United States)

    Bulbul, Esra; Miller, Eric D.; Bautz, Mark W.

    2016-04-01

    The abundance of ubiquitous dark matter is now well quantified by observations, yet its nature remains unknown. Dark matter is believed to be composed primarily of an elementary particle. The search for this particle is one of the major efforts in astrophysics and particle physics today. X-ray observations of dark matter dominated objects have the potential to reveal a signal from decaying or annihilating dark matter. We previously reported the detection of an unidentified emission line at 3.55 keV in the stacked XMM-Newton observations of galaxy clusters. The origin of this unidentified line could be attributed to the decay of dark matter particles. I will present the new results from the stacked Suzaku observations of galaxy clusters and provide a comprehensive review on the detections and limits in the literature.

  16. 350 keV accelerator based PGNAA setup to detect nitrogen in bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Naqvi, A.A., E-mail: aanaqvi@kfupm.edu.sa [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Al-Matouq, Faris A.; Khiari, F.Z.; Gondal, M.A.; Rehman, Khateeb-ur [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Isab, A.A. [Department of Chemistry, King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia); Raashid, M.; Dastageer, M.A. [Department of Physics and King Fahd University of Petroleum and Minerals, Dhahran (Saudi Arabia)

    2013-11-21

    Nitrogen concentration was measured in explosive and narcotics proxy material, e.g. anthranilic acid, caffeine, melamine, and urea samples, bulk samples through thermal neutron capture reaction using 350 keV accelerator based prompt gamma ray neutron activation (PGNAA) setup. Intensity of 2.52, 3.53–3.68, 4.51, 5.27–5.30 and 10.38 MeV prompt gamma rays of nitrogen from the bulk samples was measured using a cylindrical 100 mm×100 mm (diameter×height ) BGO detector. Inspite of interference of nitrogen gamma rays from bulk samples with capture prompt gamma rays from BGO detector material, an excellent agreement between the experimental and calculated yields of nitrogen gamma rays has been obtained. This is an indication of the excellent performance of the PGNAA setup for detection of nitrogen in bulk samples.

  17. Identification of the ~3.55 keV emission line candidate objects across the sky

    CERN Document Server

    Savchenko, Denys

    2015-01-01

    Emission line at the energy ~3.55 keV detected in different galaxies and galaxy clusters has caused a lot of discussion in high-energy astrophysics and particle physics communities. To reveal the origin of the line, we analyzed publicly available observations of MOS cameras from XMM-Newton cosmic observatory - the instrument with the largest sensitivity for narrow faint X-ray lines - previously combined in X-ray sky maps. Because of extremely large timescale needed for detailed analysis, we used the wavelet method instead. Extensive simulations of the central part of Andromeda galaxy are used to check the validity of this method. The resulting list of wavelet detections now contains 235 sky regions. This list will be used in future works for more detailed spectral analysis.

  18. Post-collisional effects on single ionization in 75 keV p + He collisions

    Energy Technology Data Exchange (ETDEWEB)

    Ciappina, M F [CONICET and Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253 (8000) BahIa Blanca (Argentina); Cravero, W R [CONICET and Departamento de Fisica, Universidad Nacional del Sur, Av. Alem 1253, B8000CPB, BahIa Blanca (Argentina); Schulz, M [Physics Department and Laboratory for Atomic, Molecular and Optical Research, University of Missouri-Rolla, Rolla, MO 65409 (United States)

    2007-07-07

    We report fully differential cross-section calculations using distorted wave theories for helium single ionization by 75 keV p impact. Comparisons are made with absolute experimental data and we find that good results are obtained in the magnitude without the need for normalization factors. However, discrepancies are quite apparent in the position and shape of the peak structures in the fully differential angular distribution of the ejected electrons. We assess the influence of the internuclear interaction on low-energy electron emission in the scattering plane and in the perpendicular plane. Our continuum distorted wave-eikonal initial state calculations with (without) the internuclear interaction yield better results for the large (small) momentum transfer. We discuss this behaviour as a consequence of active electron screening for low-energy electron emission.

  19. Direct Search for keV Sterile Neutrino Dark Matter with a Stable Dysprosium Target

    CERN Document Server

    Lasserre, T; Cribier, M; Merle, A; Mertens, S; Vivier, M

    2016-01-01

    We investigate a new method to search for keV-scale sterile neutrinos that could account for Dark Matter. Neutrinos trapped in our galaxy could be captured on stable $^{163}$Dy if their mass is greater than 2.83~keV. Two experimental realizations are studied, an integral counting of $^{163}$Ho atoms in dysprosium-rich ores and a real-time measurement of the emerging electron spectrum in a dysprosium-based detector. The capture rates are compared to the solar neutrino and radioactive backgrounds. An integral counting experiment using several kilograms of $^{163}$Dy could reach a sensitivity for the sterile-to-active mixing angle $\\sin^2\\theta_{e4}$ of $10^{-5}$ significantly exceeding current laboratory limits. Mixing angles as low as $\\sin^2\\theta_{e4} \\sim 10^{-7}$ / $\\rm m_{^{163}\\rm Dy}\\rm{(ton)}$ could possibly be explored with a real-time experiment.

  20. Mechanical engineering of a 75-keV proton injector for the Low Energy Demonstration Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Hansborough, L.D.; Hodgkins, D.J.; Meyer, E.A.; Schneider, J.D.; Sherman, J.D.; Stevens, R.R. Jr.; Zaugg, T.J.

    1997-10-01

    A dc injector capable of 75-keV, 110-mA proton beam operation is under development for the Low Energy Demonstration Accelerator (LEDA) project at Los Alamos. The injector uses a dc microwave proton source which has demonstrated 98% beam availability while operating at design parameters. A high-voltage isolation transformer is avoided by locating all ion source power supplies and controls at ground potential. The low-energy beam transport system (LEBT) uses two solenoid focusing and two steering magnets for beam matching and centroid control at the RFQ matchpoint. This paper will discuss proton source microwave window design, H{sub 2} gas flow control, vacuum considerations, LEBT design, and an iris for beam current control.

  1. 200 keV Xe+ ions irradiation effects on Zr-Ti binary films

    Science.gov (United States)

    Wang, Weipeng; Chai, Maosheng; Feng, Wei; Li, Zhengcao; Zhang, Zhengjun

    2015-05-01

    200 keV Xenon irradiation experiments were performed on magnetron sputtered Zr-Ti films under different doses up to 9 * 1015 ions/cm2. XRD, FE-SEM, AFM, HRTEM, nano-indentation and white light interferometer characterizations were applied to study the structural and mechanical properties modification introduced by the bombardment. Upon Xenon irradiation, structure of film matrix kept stable while the crystallinity of the top surface degraded significantly. Meanwhile, properties of irradiated films such as hardness, modulus and sheet resistance evolved with the same tendency, i.e. increased firstly and decrease with further increasing the irradiation dose. By selective area irradiation, competition between the surface sputtering and swelling was revealed, by which surface defects evolution was highlighted. The micro-defects evolution during Xenon irradiation was believed to be responsible for the macro-properties' modification.

  2. 200 keV Xe{sup +} ions irradiation effects on Zr–Ti binary films

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Weipeng; Chai, Maosheng [Key laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Feng, Wei [Division of CEFR Project, China Institute of Atomic Energy, Beijing 102413 (China); Li, Zhengcao [Key laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China); Zhang, Zhengjun, E-mail: zjzhang@tsinghua.edu.cn [Key laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2015-05-01

    200 keV Xenon irradiation experiments were performed on magnetron sputtered Zr–Ti films under different doses up to 9 * 10{sup 15} ions/cm{sup 2}. XRD, FE-SEM, AFM, HRTEM, nano-indentation and white light interferometer characterizations were applied to study the structural and mechanical properties modification introduced by the bombardment. Upon Xenon irradiation, structure of film matrix kept stable while the crystallinity of the top surface degraded significantly. Meanwhile, properties of irradiated films such as hardness, modulus and sheet resistance evolved with the same tendency, i.e. increased firstly and decrease with further increasing the irradiation dose. By selective area irradiation, competition between the surface sputtering and swelling was revealed, by which surface defects evolution was highlighted. The micro-defects evolution during Xenon irradiation was believed to be responsible for the macro-properties’ modification.

  3. Silicon-carbon bond inversions driven by 60-keV electrons in graphene.

    Science.gov (United States)

    Susi, Toma; Kotakoski, Jani; Kepaptsoglou, Demie; Mangler, Clemens; Lovejoy, Tracy C; Krivanek, Ondrej L; Zan, Recep; Bangert, Ursel; Ayala, Paola; Meyer, Jannik C; Ramasse, Quentin

    2014-09-12

    We demonstrate that 60-keV electron irradiation drives the diffusion of threefold-coordinated Si dopants in graphene by one lattice site at a time. First principles simulations reveal that each step is caused by an electron impact on a C atom next to the dopant. Although the atomic motion happens below our experimental time resolution, stochastic analysis of 38 such lattice jumps reveals a probability for their occurrence in a good agreement with the simulations. Conversions from three- to fourfold coordinated dopant structures and the subsequent reverse process are significantly less likely than the direct bond inversion. Our results thus provide a model of nondestructive and atomically precise structural modification and detection for two-dimensional materials.

  4. Electronic sputtering of solid O{sub 2} by keV Ne ions

    Energy Technology Data Exchange (ETDEWEB)

    Pedrys, Roman [Faculty of Physics, Astronomy and Applied Computer Science, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Anders, Christian [Fachbereich Physik und Forschungszentrum OPTIMAS, Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany); Urbassek, Herbert M., E-mail: urbassek@rhrk.uni-kl.de [Fachbereich Physik und Forschungszentrum OPTIMAS, Universität Kaiserslautern, Erwin-Schrödinger-Straße, D-67663 Kaiserslautern (Germany)

    2015-07-01

    Sputtering of a solid oxygen target is studied both by experiment and by computer simulation. Experimental data of the translational energy distributions of sputtered O{sub 2} molecules are measured for 250 and 750 eV Ne impact; this process is also studied using molecular dynamics computer simulation. Translational energy distributions coincide well for high ejection energies; this proves that the collisional part of the sputtering process is well described by computer simulation. Deviations exist at the low-energy side, below around 0.3 eV; these are assigned to electronic excitations and exothermic chemical reactions that have not been included in the computer model. We show that the sputter contribution from electronic excitation is very similar to that found for 2–9 keV H{sub 2} and H{sub 3} impact and for electron impact at sub-keV energies. Our results thus allow us to separate collisional from electronic sputtering.

  5. Magnetic field design for a Penning ion source for a 200 keV electrostatic accelerator

    Science.gov (United States)

    Fathi, A.; Feghhi, S. A. H.; Sadati, S. M.; Ebrahimibasabi, E.

    2017-04-01

    In this study, the structure of magnetic field for a Penning ion source has been designed and constructed with the use of permanent magnets. The ion source has been designed and constructed for a 200 keV electrostatic accelerator. With using CST Studio Suite, the magnetic field profile inside the ion source was simulated and an appropriate magnetic system was designed to improve particle confinement. Designed system consists of two ring magnets with 9 mm distance from each other around the anode. The ion source was constructed and the cylindrical magnet and designed magnetic system were tested on the ion source. The results showed that the ignition voltage for ion source with the designed magnetic system is almost 300 V lower than the ion source with the cylindrical magnet. Better particle confinement causes lower voltage discharge to occur.

  6. The Mont Blanc mystery solved? A $m^2=-0.28 keV^2$ neutrino

    CERN Document Server

    Ehrlich, Robert

    2016-01-01

    Evidence is presented in support of a hypothesis made in 2013 predicting the existence of a tachyonic neutrino mass eigenstate doublet having $m^2\\approx -0.2 keV^2$ with $\\Delta m^2=1 eV^2.$ The evidence is based primarily on the puzzling LSD (Mont Blanc) neutrino burst observed on February 23, 1987, which the hypothesis thoroughly explains, with additional support from the Kamiokande-II events recorded on the same day. The probability of the null hypothesis, i.e., that background fluctuations can explain the noted features of the two data sets is estimated to be $4.2\\sigma$ (Mont Blanc), and $3.7\\sigma$ (K-II). Such a controversial hypothesis as a tachyonic neutrino requires absolutely definitive proof, and there may exist a test based on observing the neutrino spectrum from diffuse supernovae that could supply it.

  7. Electronic sputtering of solid nitrogen and oxygen by keV electrons

    DEFF Research Database (Denmark)

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

    1986-01-01

    Sputtering of solid N2 and O2 has been performed with electrons in the keV regime by means of a quartz microbalance technique. Good agreement is found between the sputtering yields obtained with this and the emissivity-change method. O2 sputters more efficiently than N2, although these solids...... are very similar in their physical properties. The yields are almost proportional to the electronic stopping power of the primary electrons. Different models for electronic sputtering of solid condensed gases are discussed and compared with the results. For low excitation densities predictions...... are attempted on the basis of a simple collision-cascade model where the low-energy cascades are generated by kinetic energy release from electronic deexcitations....

  8. Charge transfer and excitation in H++CH3 collisions below 10keV

    Science.gov (United States)

    Nagao, Masatoshi; Hida, Ken-Nosuke; Kimura, Mineo; Rai, Sachchida N.; Liebermann, Heinz-Peter; Buenker, Robert J.; Suno, Hiroya; Stancil, Phillip C.

    2008-07-01

    Charge transfer and electronic excitation in collisions of H+ ions with CH3 from a few tens of eV up to 10keV are theoretically investigated. The adiabatic potential energy curves and corresponding wave functions are calculated by using the multireference single- and double-excitation configuration interaction method, and the scattering dynamics is studied based on the semiclassical impact parameter molecular-orbital close-coupling approach. Charge-transfer cross sections are found to be large and rather energy-dependent over the entire energy region studied. Electronic excitation is also energy-dependent with a sharp increase from below 10-17to10-16cm2 . Most of the molecular products produced through charge transfer or excitation are known to be unstable and undergo fragmentation producing various hydrocarbon radical species. Hence, identification of fragmented species and their production mechanism are important for spectroscopic analysis.

  9. Laboratory source based full-field x-ray microscopy at 9 keV

    Energy Technology Data Exchange (ETDEWEB)

    Fella, C.; Balles, A.; Wiest, W. [Lehrstuhl für Röntgenmikroskopie, Julius-Maximilians-Universität, 97074 Würzburg (Germany); Zabler, S.; Hanke, R. [Lehrstuhl für Röntgenmikroskopie, Julius-Maximilians-Universität, 97074 Würzburg (Germany); Fraunhofer Development Center X-Ray Technology (EZRT), Flugplatzstrasse 75, 90768 Fürth (Germany)

    2016-01-28

    In the past decade, hard x-ray transmission microscopy experienced tremendous developments. With the avail-ability of efficient Fresnel zone plates, even set-ups utilizing laboratory sources were developed [1]. In order to improve the performance of these x-ray microscopes, novel approaches to fabricate optical elements [2] and brighter x-ray tubes [3] are promising candidates. We are currently building a laboratory transmission x-ray microscope for 9.25 keV, using an electron impact liquid-metal-jet anode source. Up to now, the further elements of our setup are: a polycapillary condenser, a tungsten zone plate, and a scintillator which is optically coupled to a CMOS camera. However, further variations in terms of optical elements are intended. Here we present the current status of our work, as well as first experimental results.

  10. Charge states distribution of 3350 keV He ions channeled in silicon

    CERN Document Server

    Bentini, G G; Bianconi, M; Lotti, R; Lulli, G

    2002-01-01

    When an ion beam is aligned along a major crystalline axis the dominant interaction is with valence electrons. In this condition the charge exchange processes mostly concern the interaction between the incident ion and a quasi-free electron gas and a strong reduction of the charge-changing probabilities is expected. In this work, 3350 keV He sup + and He sup 2 sup + ions were aligned at small tilt angles about the axis of a 4650 A silicon crystalline membrane. The charge state distribution (CSD) of the transmitted ions was detected by an electro-magnetic analyzer having a very small acceptance angle. In these conditions the equilibration of the CSD was not yet reached and this allowed, making use of simple approximations, for the measurement of the valence electron loss cross-section.

  11. Defects in 700 keV oxygen ion irradiated ZnO

    Energy Technology Data Exchange (ETDEWEB)

    Pal, S. [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009 (India); Sarkar, A. [Department of Physics, Bangabasi Morning College, 19 Rajkumar Chakraborty Sarani, Kolkata 700009 (India); Chattopadhyay, S. [Department of Basic Science and Humanities, Calcutta Institute of Engineering and Management, 24/1A Chandi Ghosh Road, Kolkata 700040 (India); Chakrabarti, Mahuya [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009 (India); Sanyal, D. [Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700064 (India); Kumar, P.; Kanjilal, D. [Inter-University Accelerator Centre, P.O. Box 10502, Aruna Asaf Ali Marg, New Delhi 110067 (India); Rakshit, T.; Ray, S.K. [Department of Physics and Meteorology, Indian Institute of Technology, Kharagpur 721302 (India); Jana, D., E-mail: djphy@caluniv.ac.in [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700009 (India)

    2013-09-15

    Highlights: •ZnO samples (both poly and single crystal) have been irradiated with 700 keV O ions. •Non-monotonic variation of room temperature sheet resistance has been observed. •NBE PL emission is largely reduced due to O ion irradiation. •Absorption spectrum of irradiated ZnO crystal show a sub-band gap absorption. •Oxygen irradiation generated new absorption band in ZnO is at 3.05 eV. -- Abstract: It is well known that energetic oxygen ions induce heavy crystalline disorder in ZnO, however, systematic study on this regard is very much limited. Here, we present photoluminescence (PL), optical absorption and sheet resistance measurements on poly and single crystalline ZnO samples irradiated with 700 keV O ions. Results have been compared with the effects of 1.2 MeV Ar irradiation on similar ZnO target. Colour change of the samples with increasing O irradiation fluence has also been noted. Non-monotonic variation of room temperature sheet resistance with the increase of fluence has been observed for polycrystalline ZnO. Such an outcome has been understood as point defects transforming to bigger size clusters. Near band edge (NBE) PL emission is largely reduced due to O ion irradiation. However, at 10 K NBE emission can be observed for irradiated polycrystalline samples. Irradiated ZnO single crystal does not show any band to band transition even at 10 K. It is evident that dynamic recovery of defects is more effective in polycrystalline samples. Ultraviolet–visible absorption spectrum of the irradiated ZnO crystal show pronounced sub-band gap absorption. Oxygen irradiation generated new absorption band in ZnO is at 3.05 eV. In the light of earlier reports, this particular band can be ascribed to absorption by neutral oxygen vacancy defects.

  12. keV sterile neutrino dark matter from singlet scalar decays: basic concepts and subtle features

    Energy Technology Data Exchange (ETDEWEB)

    Merle, Alexander; Totzauer, Maximilian [Max-Planck-Institut für Physik (Werner-Heisenberg-Institut), Föhringer Ring 6, 80805 München (Germany)

    2015-06-08

    We perform a detailed and illustrative study of the production of keV sterile neutrino Dark Matter (DM) by decays of singlet scalars in the early Universe. In the current study we focus on providing a clear and general overview of this production mechanism. For the first time we study all regimes possible on the level of momentum distribution functions, which we obtain by solving a system of Boltzmann equations. These quantities contain the full information about the production process, which allows us to not only track the evolution of the DM generation but to also take into account all bounds related to the spectrum, such as constraints from structure formation or from avoiding too much dark radiation. In particular we show that this simple production mechanism can, depending on the regime, lead to strongly non-thermal DM spectra which may even feature more than one peak in the momentum distribution. These cases could have particularly interesting consequences for cosmological structure formation, as their analysis requires more refined tools than the simplistic estimate using the free-streaming horizon. Here we present the mechanism including all concepts and subtleties involved, for now using the assumption that the effective number of relativistic degrees of freedom is constant during DM production, which is applicable in a significant fraction of the parameter space. This allows us to derive analytical results to back up our detailed numerical computations, thus leading to the most comprehensive picture of keV sterile neutrino DM production by singlet scalar decays that exists up to now.

  13. Ionization and fragmentation of polycyclic aromatic hydrocarbon clusters in collisions with keV ions

    Energy Technology Data Exchange (ETDEWEB)

    Johansson, H. A. B.; Zettergren, H.; Holm, A. I. S.; Seitz, F.; Schmidt, H. T.; Cederquist, H. [Department of Physics, Stockholm University, SE-106 91, Stockholm (Sweden); Rousseau, P.; Lawicki, A.; Capron, M.; Domaracka, A.; Lattouf, E.; Maclot, S.; Maisonny, R.; Chesnel, J.-Y.; Adoui, L.; Huber, B. A. [CIMAP, UMR 6252, CEA/CNRS/ENSICAEN/Universite de Caen Basse-Normandie, Boulevard Henri Becquerel, BP5133, F-14070 Caen Cedex 5 (France); Manil, B. [Laboratoire de Physique des Laser, CNRS, UMR 7538, Institut Galilee, Universite Paris 13, F-93430, Villetaneuse (France)

    2011-10-15

    We report on an experimental study of the ionization and fragmentation of clusters of k polycyclic aromatic hydrocarbon (PAH) molecules using anthracene, C{sub 14}H{sub 10}, or coronene, C{sub 24}H{sub 12}. These PAH clusters are moderately charged and strongly heated in small impact parameter collisions with 22.5-keV He{sup 2+} ions, after which they mostly decay in long monomer evaporation sequences with singly charged and comparatively cold monomers as dominating end products. We describe a simple cluster evaporation model and estimate the number of PAH molecules in the clusters that have to be hit by He{sup 2+} projectiles for such complete cluster evaporations to occur. Highly charged and initially cold clusters are efficiently formed in collisions with 360-keV Xe{sup 20+} ions, leading to cluster Coulomb explosions and several hot charged fragments, which again predominantly yield singly charged, but much hotter, monomer ions than the He{sup 2+} collisions. We present a simple formula, based on density-functional-theory calculations, for the ionization energy sequences as functions of coronene cluster size, rationalized in terms of the classic electrostatic expression for the ionization of a charged conducting object. Our analysis indicates that multiple electron removal by highly charged ions from a cluster of PAH molecules rapidly may become more important than single ionization as the cluster size k increases and that this is the main reason for the unexpectedly strong heating in these types of collisions.

  14. Large angle elastic and inelastic scattering of 14.93 keV photons

    Energy Technology Data Exchange (ETDEWEB)

    Singh, P.; Mehta, D.; Kumar, S.; Sharma, M.; Puri, S.; Shahi, J.S.; Singh, N. E-mail: nsingh@pu.ac.in

    2004-07-01

    Elastic and inelastic scattering cross-sections for the 14.93 keV photons (Y-K{alpha} X-rays) were measured at an angle of 141 deg. in the elements with 6 {<=} Z {<=} 92 and 1 {<=} Z {<=} 50, respectively. A reflection mode geometrical arrangement involving a Y-foil excited by the 59.54 keV {gamma}-rays from the {sup 241}Am radioisotope as photon source and an HPGe/Si(Li) detector was used. The measurements were performed under vacuum {approx}10{sup -2} Torr. Special care was taken in determination of the incident photon intensity and geometrical factors and to check effects due to occurrence of Bragg diffraction from the target lattice. The measured elastic scattering cross-sections have been compared with predictions from the form-factor formalism and relativistic second-order S-matrix calculations. The modified form-factor (MF) cross-sections are higher up to 50% than the measured ones in the case of elements with the electron binding energy (BE) in vicinity of the incident photon energy and are lower up to 20% for the other elements. These deviations are smoothed by incorporating the Anomalous Scattering Factors (ASFs) to the MF values [Acta Cryst. A 46 (1990) 170]. The S-matrix values exhibit general agreement with the measured cross-sections. The measured inelastic scattering cross-sections are found to be in good agreement with those calculated using the Klein-Nishina cross-section incorporating the Hartree-Fock incoherent scattering function (ISF)

  15. Preparation of radiotherapy glass by phosphorus ion implantation at 100 keV.

    Science.gov (United States)

    Kawashita, M; Miyaji, F; Kokubo, T; Takaoka, G H; Yamada, I; Suzuki, Y; Kajiyama, K

    1997-01-01

    A chemically durable glass containing a large amount of phosphorus is useful for in situ irradiation of cancers. It can be activated to be a beta emitter (half-life of 14.3 days) by neutron bombardment. Microspheres of the activated glass injected into the tumors can irradiate the tumors directly with beta rays without irradiating neighboring normal tissues. In the present study a P+ ion was implanted into a pure silica glass in a plate form at 100 keV in order to find the fundamental conditions for obtaining such a glass. Little phosphorus was present in the surface region, at least to a depth of 2.4 nm for doses of 5 x 10(16) and 1 x 10(17) cm-2, whereas an appreciable amount of it was distributed on the glass surface and a part of it was oxidized for doses above 5 x 10(17) cm-2. The glasses implanted with doses of 5 x 10(16) and 1 x 10(17) cm-2 hardly released the P and Si into water at 95 degrees C, even after 7 days, whereas the glasses implanted with doses above 5 x 10(17) cm-2 released appreciable amounts of these elements. Implantation energies of 20 and 50 keV (even at doses of 5 x 10(16) and 1 x 10(17) cm-2, respectively), formed oxidized phosphorus on the glass surfaces and gave appreciable release of the P and Si into the hot water. This indicates that a chemically durable glass containing a larger amount of phosphorus could be obtained if a P+ ion is implanted at higher energies to localize in a deeper region of the glass surface.

  16. Influence of 400 keV carbon ion implantation on structural, optical and electrical properties of PMMA

    Energy Technology Data Exchange (ETDEWEB)

    Arif, Shafaq, E-mail: sarif2005@gmail.com [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Rafique, M. Shahid [Department of Physics, University of Engineering & Technology, Lahore 54000 (Pakistan); Saleemi, Farhat; Sagheer, Riffat [Department of Physics, Lahore College for Women University, Lahore 54000 (Pakistan); Naab, Fabian; Toader, Ovidiu [Department of Nuclear Engineering and Radiological Sciences, Michigan Ion Beam Laboratory, University of Michigan, MI 48109-2104 (United States); Mahmood, Arshad; Rashid, Rashad [National Institute of Lasers and Optronics (NILOP), P.O. Nilore, Islamabad (Pakistan); Mahmood, Mazhar [Department of Metallurgy & Materials Engineering, Pakistan Institute of Engineering & Applied Sciences (PIEAS), Islamabad (Pakistan)

    2015-09-01

    Ion implantation is a useful technique to modify surface properties of polymers without altering their bulk properties. The objective of this work is to explore the 400 keV C{sup +} ion implantation effects on PMMA at different fluences ranging from 5 × 10{sup 13} to 5 × 10{sup 15} ions/cm{sup 2}. The surface topographical examination of irradiated samples has been performed using Atomic Force Microscope (AFM). The structural and chemical modifications in implanted PMMA are examined by Raman and Fourier Infrared Spectroscopy (FTIR) respectively. The effects of carbon ion implantation on optical properties of PMMA are investigated by UV–Visible spectroscopy. The modifications in electrical conductivity have been measured using a four point probe technique. AFM images reveal a decrease in surface roughness of PMMA with an increase in ion fluence from 5 × 10{sup 14} to 5 × 10{sup 15} ions/cm{sup 2}. The existence of amorphization and sp{sup 2}-carbon clusterization has been confirmed by Raman and FTIR spectroscopic analysis. The UV–Visible data shows a prominent red shift in absorption edge as a function of ion fluence. This shift displays a continuous reduction in optical band gap (from 3.13 to 0.66 eV) due to formation of carbon clusters. Moreover, size of carbon clusters and photoconductivity are found to increase with increasing ion fluence. The ion-induced carbonaceous clusters are believed to be responsible for an increase in electrical conductivity of PMMA from (2.14 ± 0.06) × 10{sup −10} (Ω-cm){sup −1} (pristine) to (0.32 ± 0.01) × 10{sup −5} (Ω-cm){sup −1} (irradiated sample)

  17. Photon-induced L X-ray production differential cross sections in thorium at 22.6 keV

    Energy Technology Data Exchange (ETDEWEB)

    Puri, Sanjiv; Mehta, D.; Shahi, J.S.; Garg, M.L.; Singh, Nirmal; Trehan, P.N

    1999-04-01

    The Ll, L{alpha}, L{beta}{sub 2,4}, L{beta}{sub 1,3} and L{gamma}{sub 1,5} X-ray production differential cross sections in {sub 90}Th have been measured at 22.6 keV incident photon energy in an angular range 50-130 deg. The measurements were performed using a {sup 109}Cd annular-source and a Si(Li) detector. The measured differential cross sections for various L X-rays are found to be angle-independent within experimental error. This is contrary to the strong angular-dependence of photon-induced Ll and L{alpha} X-ray production cross sections as reported by Kahlon et al. (K.S. Kahlon, H.S. Aulakh, N. Singh, R. Mittal, K.L. Allawadhi, B.S. Sood, Phys. Rev. A 43 (1991) 1455) and Ertugrul (M. Ertugrul, Nucl. Instr. and Meth. B 119 (1996) 345). Integral cross sections for production of Ll, L{alpha}, L{eta}, L{beta}{sub 6}, L{beta}{sub 2,4}, L{beta}{sub 1,3}, L{beta}{sub 9,10}, L{gamma}{sub 1,5} and total L{gamma} X-rays are also deduced and are found to be in good agreement with those calculated using reliable theoretical values of the L{sub i} (i=1, 2, 3) subshell photoionisation cross sections, fluorescence yields, X-ray emission rates and Coster-Kronig transition probabilities.

  18. Observational evidences for the existence of 17.4 keV decaying degenerate sterile neutrinos near the Galactic Center

    CERN Document Server

    Chan, Man Ho

    2010-01-01

    We show that the existence of a degenerate halo of sterile neutrinos with rest mass of 17.4 keV near the Galactic Center can account for both the excess 8.7 keV emission observed by the $Suzaku$ mission and the power needed ($10^{40}$ erg s$^{-1}$) to maintain the high temperature of the hot gas (8 keV) near the Galactic Center. The required decay rate and mixing angle of the sterile neutrinos are $\\Gamma \\ge 5 \\times 10^{-20}$ s$^{-1}$ and $\\sin^22 \\theta \\sim 10^{-3}-10^{-4}$ respectively. These values are consistent with a low reheating temperature in the inflation model, and suggest the exciting possibility that the sterile - active neutrino oscillation can be visible in near future experiments.

  19. Secondary emission yields for 3-50 keV H[sup 0] atoms striking a copper target

    Energy Technology Data Exchange (ETDEWEB)

    Allen, J.S. (Dept. of Physics and Astronomy, Univ. of Toledo, OH (United States)); Fang, X.D. (Dept. of Physics and Astronomy, Univ. of Toledo, OH (United States)); Kvale, T.J. (Dept. of Physics and Astronomy, Univ. of Toledo, OH (United States))

    1993-06-01

    By measuring the fractions of all three charged particles (H[sup -], H[sup +], and H[sup 0]) emerging from energetic (3-50 keV) collisions of H[sup -] ions with helium atoms, the absolute secondary negative particle emission yields [gamma] have been determined for H[sup 0] atoms striking a copper surface at an angle of incidence of 30 relative to the normal to the copper surface. The measured secondary emission yields monotonically increase from a value of 1.6 negative particles per atom at an incident energy of 3 keV to a value of 4.0 negative particles per atom at an incident energy of 50 keV. The impact energy dependence of the yield [gamma] is found to be similar to the energy dependence of the yield [gamma] exhibited by the data of previous investigators, which were obtained at projectile angles of incidence different from 30 . (orig.)

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

    Science.gov (United States)

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

    2013-09-01

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

  1. Tables and graphs of photon-interaction cross sections from 0. 1 keV to 100 MeV derived from the LLL evaluated-nuclear-data library

    Energy Technology Data Exchange (ETDEWEB)

    Plechaty, E.F.; Cullen, D.E.; Howerton, R.J.

    1981-11-11

    Energy-dependent evaluated photon interaction cross sections and related parameters are presented for elements H through Cf(Z = 1 to 98). Data are given over the energy range from 0.1 keV to 100 MeV. The related parameters include form factors and average energy deposits per collision (with and without fluorescence). Fluorescence information is given for all atomic shells that can emit a photon with a kinetic energy of 0.1 keV or more. In addition, the following macroscopic properties are given: total mean free path and energy deposit per centimeter. This information is derived from the Livermore Evaluated-Nuclear-Data Library (ENDL) as of October 1978.

  2. Free ion yields for nonpolar liquids exposed to 1.6-3.5 keV X-rays

    CERN Document Server

    Holroyd, R A

    1998-01-01

    The yields of free ions formed following absorption of 1.6-3.5 keV X-rays were determined for several nonpolar liquids using a conductivity technique. The yields are much less for X-rays than for gamma rays; this effect is largest for branched hydrocarbons. A minimum in yield is observed around 2 keV. The dependence of G sub f sub i sup o on X-ray energy is in good agreement with computer simulations. For tetramethylsilane a sharp dip in ion yield is observed at the Si ls -> sigma sup * resonance, indicating that the free electron yield is even less at this energy.

  3. Extrapolation Ionization Chamber Dosimetry of Fluorescent X-Ray Energies from 4.5 to 19.6 keV.

    Science.gov (United States)

    Rakowski, Joseph T; Tucker, Mark A; Snyder, Michael G; Makar, Simon P; Yudele, Mark; Burmeister, Jay; Joiner, Michael C

    2016-09-01

    Characteristic X rays of energies less than approximately 20 keV are of interest in radiobiology and radiation oncology. There is evidence that these low-energy photons produce higher relative biological effectiveness (RBE) and lower oxygen enhancement ratio (OER) relative to higher energies. Lower energy X rays also offer the advantage of healthy tissue sparing beyond the target treatment depth. Electronic brachytherapy systems that can deliver characteristic and bremsstrahlung X rays of varying energy are in clinical use as well as under development. We performed low-energy extrapolation ionization chamber dosimetry using two methods: 1. the exposure-to-dose method; and 2. the Burlin theory method combined with the extrapolation chamber method of Klevenhagen. We investigated fluorescent X rays emitted from seven metals: titanium (Ti, Z = 22); chromium (Cr, Z = 24); iron (Fe, Z = 26); cobalt (Co, Z = 27); copper (Cu, Z = 29); zinc (Zn, Z = 30); and molybdenum (Mo, Z = 42). X rays were produced by irradiation of the metals with a 55 kVp, 45 mA silver anode spectrum. The data obtained were air kerma rate (cGy/min), and radiation dose rate (cGy/min) in phosphate-buffered saline (PBS) solution and water. Air kerma rates ranged from 3.55 ± 0.10 to 14.36 ± 0.39 cGy/min. Dose rates ranged from 3.85 ± 0.10 to 16.96 ± 0.46 cGy/min in PBS and 3.59 ± 0.10 to 16.06 ± 0.43 cGy/min in water. Dose-rate energy dependence of both models was examined by taking a ratio of measured to Monte Carlo calculated dose rates. Dosimetry method 1 exhibited a linear relationship across all energies with a slope of 0.0127 keV(-1) and R(2) of 0.9276. Method 2 exhibited a linear relationship across all energies with a slope of 0.0467 keV(-1) and R(2) of 0.9933. Method 1 or 2 may be used as a relative dosimetry system to derive dose rates to water by using a second reference ion chamber with a NIST-traceable calibration for the molybdenum spectrum.

  4. Ag K-shell ionization by electron impact: New cross-section measurements between 50 and 100 keV and review of previous experimental data

    Science.gov (United States)

    Vanin, V. R.; Manso Guevara, M. V.; Maidana, N. L.; Martins, M. N.; Fernández-Varea, J. M.

    2016-02-01

    We report the measurement of Ag K-shell ionization cross-section by electron impact in the range 50-100 keV and review the experimental data found in the literature. The sample consisted in a thin film of Ag evaporated on a thin C backing. The x-ray spectra generated by electron bombardment in the São Paulo Microtron were observed with a planar HPGe detector. The ratios between characteristic and bremsstrahlung x-ray yields were transformed to ionization cross sections with the help of theoretical atomic-field bremsstrahlung cross sections. The measured cross sections are compared with existing experimental values and calculations based on the semi-relativistic distorted-wave Born approximation. According to our experiment, the ratio of Ag Kβ to Kα x-ray intensities is 0.2018(24).

  5. Determination of the 25Mg( p, γ)26Al resonance strength at E c.m.=58 keV via shell model calculation

    Science.gov (United States)

    Li, ZhiHong; Su, Jun; Li, YunJu; Guo, Bing; Li, ErTao; Wang, YouBao; Yan, ShengQuan; Liu, WeiPing

    2015-08-01

    The observation of 26Al is an useful tool for γ-ray astronomy and in studies of galactic chemical evolution. The most likely mechanism for 26A1 nucleosynthesis is in the hydrogen burning MgAl cycle, and the 26A1 production reaction 25Mg( p, γ)26Al at the important temperature range below T = 0.2 GK is still not well known. The spectroscopic factor of 58 keV resonance level in 26A1 is determined with shell model calculation and then used to deduce the resonance strength of the 25Mg( p, γ)26Al reaction. The result provides a reference for the future 25Mg( p, γ)26Al direct measurement at Jinping underground laboratory.

  6. Observations of energetic electrons /E no less than about 200 keV/ in the earth's magnetotail - Plasma sheet and fireball observations

    Science.gov (United States)

    Baker, D. N.; Stone, E. C.

    1977-01-01

    An earlier paper by the authors (1976) has reported on energetic electron anisotropies observed in conjunction with the acceleration regions identified by Frank et al., (1976). The present paper gives more detailed analyses of observations in the distant plasma sheet, including specific features of intensities, energy spectra, and pitch angle distributions of the very energetic electrons associated with intense plasma particle events, with energies ranging between 50 eV and 45 keV, detected with an electron/isotope spectrometer aboard the earth-orbiting spacecraft Imp 8. Two domains are considered: the plasma sheet and the regions near and within the localized magnetotail acceleration regions known as the fireball regions. The instrumentation used offered a number of observational advantages over many previous studies, including inherently low background, large geometric factors, excellent species identification, good angular distribution measurement capability, and availability of high resolution of differential intensities.

  7. Total L-shell X-ray production cross sections by 400-700 keV proton impact for elements with 34{<=}Z{<=}53

    Energy Technology Data Exchange (ETDEWEB)

    Miranda, J. E-mail: miranda@fenix.ifisicacu.unam.mx; Ledesma, R.; Lucio, O.G. de

    2001-03-01

    Total L-shell X-ray production cross sections induced by protons with energies between 400 and 700 keV were measured for elements with atomic number Z between 34 and 53. The ECPSSR theory describes appropriately the results. This model modifies the plane wave born approximation by considering projectile energy loss (E), Coulomb deflection of the incoming ion (C), polarization and change in electron binding energies through a perturbed stationary states method (PSS) and relativistic values of target electron mass (R). A comparison is given with previously published data for proton energies below 1 MeV and 26 {<=} Z {<=} 53, based on a scaling obtained from a reduced velocity parameter {xi}{sub L}{sup R}. The results show that the scaling for these atomic numbers and energy ranges is adequate and a semi-empirical expression to calculate those cross sections is proposed.

  8. Visible and near UV photon spectroscopy of charge-exchange collisions between Ar7+ and Li at 105 keV

    Science.gov (United States)

    Jacquet, E.; Boduch, P.; Chantepie, M.; Druetta, M.; Hennecart, D.; Husson, X.; Lecler, D.; Wilson, M.

    1994-04-01

    Charge exchange collisions at 105 keV between Ar7+ ions and lithium atoms have been studied by photon spectroscopy in the 2000-6000 Å wavelength range. A large number of new lines in Ar VII have been identified with the help of ab initio pseudo-relativistic Hartree-Fock calculations taking into account electrostatic interactions between 3snl (n = 6-10), 3 pnl (n = 4-6) and 3dnl (n = 4) configurations. They correspond to transitions 3snl-3sn'l' with n = 7, 8, 9 and Δn = 1 and 2. Lines in Ar VI were also observed and identified as transitions 3s2nl-3s2n'l' and 3s3pnl-3s3pn'l'(n = 6, 7) and Δn = 1.

  9. Measurement of L X-ray fluorescence cross-sections for elements with 45 {<=} Z {<=} 50 using synchrotron radiation at 8 keV

    Energy Technology Data Exchange (ETDEWEB)

    Bonzi, Edgardo V., E-mail: bonzie@famaf.unc.edu.ar [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria - 5010, Cordoba (Argentina); Badiger, Nagappa M. [Departments of Physics, Karnataka University, Dharwad 580 003, Karnataka (India); Grad, Gabriela B. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria - 5010, Cordoba (Argentina); Barrea, Raul A. [The Biophysics Collaborative Access Team (BioCAT), Department of Biological Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States); Figueroa, Rodolfo G. [Departamento de Cs. Fisicas, Universidad de La Frontera, Temuco (Chile)

    2011-10-01

    The L shell fluorescence cross-sections of the elements in range 45 {<=} Z {<=} 50 have been determined at 8 keV using Synchrotron radiation. The individual L X-ray photons, Ll, L{alpha}, L{beta}{sub I}, L{beta}{sub II}, L{gamma}{sub I} and L{gamma}{sub II} produced in the target were measured with high resolution Si(Li) detector. The experimental set-up provided a low background by using linearly polarized monoenergetic photon beam, improving the signal-to-noise ratio. The experimental cross-sections obtained in this work were compared with available experimental data from Scofield Krause and Scofield and Puri et al. . These experimental values closely agree with the theoretical values calculated using Scofield and Krause data, except for the case of L{gamma}, where values measured of this work are slighter higher.

  10. Coherent to incoherent cross section ratio for 59.54 keV gamma rays at scattering angle of 110°

    Energy Technology Data Exchange (ETDEWEB)

    Singh, M. P.; Singh, Bhajan; Sandhu, B. S., E-mail: balvir@pbi.ac.in [Physics Department, Punjabi University, Patiala 147002 (India); Sharma, Amandeep [Deptt. of Math. Stat. & Physics, Punjab Agricultural University, Ludhiana 141004 (India)

    2015-08-28

    The coherent (Rayleigh) to incoherent (Compton) scattering cross-section ratio of elements, in the range 13 ≤ Z ≤ 82, are determined experimentally for 59.54 keV incident gamma photons. An HPGe (High purity germanium) semiconductor detector is employed, at scattering angle of 110°, 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 based upon non-relativistic form factor, relativistic form factor, modified form factor and S-matrix theory.

  11. Sputtering of SiN films by 540 keV C{sub 60}{sup 2+} ions observed using high-resolution Rutherford backscattering spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, K.; Morita, Y.; Kitayama, T.; Suzuki, M. [Department of Micro Engineering, Kyoto University, Kyoto 615-8540 (Japan); Narumi, K.; Saitoh, Y. [Takasaki Advanced Radiation Research Institute, Japan Atomic Energy Agency, 1233 Watanuki-machi, Takasaki, Gumma 370-1292 (Japan); Tsujimoto, M.; Isoda, S. [Institute for Integrated Cell-Material Sciences, Kyoto University, Kyoto 606-8501 (Japan); Fujii, Y. [Center for Supports to Research and Education Activities, Kobe University, Kobe 657-8501 (Japan); Kimura, K., E-mail: kimura@kues.kyoto-u.ac.jp [Department of Micro Engineering, Kyoto University, Kyoto 615-8540 (Japan)

    2014-08-01

    Amorphous silicon nitride films deposited on Si(0 0 1) were irradiated with 540 keV C{sub 60} ions to fluences ranging from 2.5 × 10{sup 11} to 1 × 10{sup 14} ions/cm{sup 2}. The composition depth profiles of the irradiated samples were measured using high-resolution Rutherford backscattering spectroscopy. Both silicon and nitrogen in the film decrease rapidly with fluence. From the observed result the sputtering yields are obtained as 3900 ± 500 N atoms/ion and 1500 ± 1000 Si atoms/ion. Such large sputtering yield cannot be explained by either the elastic sputtering or the electronic sputtering, indicating that the synergy effect between the elastic sputtering and the electronic sputtering plays an important role.

  12. Ionization and fragmentation of RNA base molecule uracil in collisions with carbon ions of energies between 100 keV and 60 MeV

    Science.gov (United States)

    Tribedi, L. C.; Agnihotri, A. N.; Kasthurirangan, S.; Kumar, A.; Champion, C.; Rivarola, R.

    2012-11-01

    We report here the first measurement of absolute single ionization cross-section of uracil (C4H4N2O2, m=112) in collisions with highly charged C ions of energy ranging between 100 keV to 60 MeV i.e. in the range of Bragg peak which is relevant for high energy hadron therapy. An ECR based low energy accelerator along with a 14 MV Pelletron accelerator were used to obtain a wide range of energies. Energy and charge state (representing perturbation strength) dependence of io-nization cross-section has been studied using a ToF mass spectrometer. In the low energy range, cross-section increases with energy and then saturates while in the high energy range it decreases with energy. Ionization cross-section found to increase linearly with charge-state. The CTMC and CDW-EIS models are used to compare with the data. The complementary experiment was also carried out to measure the low energy electron emission spectrum at different angles.

  13. Evolution of ripple morphology on Si(1 0 0) by 60-keV argon ions

    Energy Technology Data Exchange (ETDEWEB)

    Garg, Sandeep Kumar, E-mail: sandeep@iopb.res.in [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Venugopal, V.; Basu, T. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Sinha, O.P. [Amity Institute of Nano Technology, Amity University, Noida 201303 (India); Rath, S. [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Kanjilal, D. [Inter-Univeristy Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Som, T. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India)

    2012-02-15

    In this paper, we report on evolution of ripple morphology on Si(1 0 0) surface due to 60 keV Ar{sup +}-ion implantation to the fluence of 2 Multiplication-Sign 10{sup 18} ions cm{sup -2} and over a large incident angular window of 075 Degree-Sign . Room temperature implantations were carried out by using a uniform current density of 20 {mu}A cm{sup -2}. Atomic force microscopic (AFM) studies indicate that ripple morphology starts to appear at an incident angle 45 Degree-Sign and becomes more prominent at higher incident angles. AFM studies also reveal that while the ripple wavelength decreases with increasing angle of incidence, the amplitude increases with the same. We also observe a systematic variation in the surface roughness with incident angle. Micro-Raman studies show that the sub-surface silicon layer becomes amorphous whose depth keeps reducing at higher incident angles. The results are attributed to viscous flow mechanism.

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

    Science.gov (United States)

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

    2008-01-01

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

  15. The Swift/Fermi GRB 080928 from 1 eV to 150 keV

    CERN Document Server

    Rossi, A; Klose, S; Kann, D A; Rau, A; Krimm, H A; Jóhannesson, G; Panaitescu, A; Yuan, F; Ferrero, P; Krühler, T; Greiner, J; Schady, P; Pandey, S B; Amati, L; Afonso, P M J; Akerlof, C W; Arnold, L; Clemens, C; Filgas, R; Hartmann, D H; Yoldaş, A Küpcü; McBreen, S; McKay, T A; Guelbenzu, A Nicuesa; E., F Olivares; Paciesas, B; Rykoff, E S; Szokoly, G; Updike, A C; Yoldaş, A

    2010-01-01

    We present the results of a comprehensive study of the Gamma-Ray Burst 080928 and of its afterglow. GRB 080928 was a long burst detected by Swift/BAT and Fermi/GBM. It is one of the exceptional cases where optical emission was already detected when the GRB itself was still radiating in the gamma-ray band. For nearly 100 seconds simultaneous optical, X-ray and gamma-ray data provide a coverage of the spectral energy distribution of the transient source from about 1 eV to 150 keV. Here we analyze the prompt emission, constrain its spectral properties, and set lower limits on the initial Lorentz factor of the relativistic outflow. In particular, we show that the SED during the main prompt emission phase is in agreement with synchrotron radiation. We construct the optical/near-infrared light curve and the spectral energy distribution based on Swift/UVOT, ROTSE-IIIa (Australia) and GROND (La Silla) data and compare it to the X-ray light curve retrieved from the Swift/XRT repository. We show that its bumpy shape ca...

  16. Origins of the 1/4 keV Soft X-Ray Background

    CERN Document Server

    Bellm, E C; Bellm, Eric C.; Vaillancourt, John E.

    2005-01-01

    Snowden and coworkers have presented a model for the 1/4 keV soft X-ray diffuse background in which the observed flux is dominated by a ~ 10^6 K thermal plasma located in a 100-300 pc diameter bubble surrounding the Sun, but has significant contributions from a very patchy Galactic halo. Halo emission provides about 11% of the total observed flux and is responsible for half of the H I anticorrelation. The remainder of the anticorrelation is presumably produced by displacement of disk H I by the varying extent of the local hot bubble (LHB). The ROSAT R1 and R2 bands used for this work had the unique spatial resolution and statistical precision required for separating the halo and local components, but provide little spectral information. Some consistency checks had been made with older observations at lower X-ray energies, but we have made a careful investigation of the extent to which the model is supported by existing sounding rocket data in the Be (73-111 eV) and B bands (115-188 eV) where the sensitivities...

  17. A Spectacular Bow Shock in the 11 keV Galaxy Cluster Around 3C 438

    CERN Document Server

    Emery, Deanna L; Kraft, Ralph P; Andrade-Santos, Felipe; Forman, William R; Hardcastle, Martin J; Jones, Christine

    2016-01-01

    We present results of deep 153 ks Chandra observations of the hot, 11 keV, galaxy cluster associated with the radio galaxy 3C 438. By mapping the morphology of the hot gas and analyzing its surface brightness and temperature distributions, we demonstrate the presence of a merger bow shock. We identify the presence of two jumps in surface brightness and in density located at $\\sim$400 kpc and $\\sim$800 kpc from the cluster's core. At the position of the inner jump, we detect a factor of $2.3\\pm 0.2$ density jump, while at the location of the outer jump, we detect a density drop of a factor of $3.5 \\pm 0.7$. Combining this with the temperature distribution within the cluster, we establish that the pressure of the hot gas is continuous at the 400 kpc jump, while there is a factor of $6.2 \\pm 2.8$ pressure discontinuity at 800 kpc jump. From the magnitude of the outer pressure discontinuity, using the Rankine-Hugoniot jump conditions, we determine that the sub-cluster is moving at $M = 2.3\\pm 0.5$, or approximate...

  18. Effects of 400 keV electrons flux on two space grade silicone rubbers

    Energy Technology Data Exchange (ETDEWEB)

    Jochem, H. [ONERA – The French Aerospace Lab, F-31055 Toulouse (France); Université de Toulouse, UPS, and CNRS, LHFA, UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); CNES – French Aerospace Agency, 18 Avenue Edouard Belin, F-31401 Toulouse Cedex 9 (France); Rejsek-Riba, V. [ONERA – The French Aerospace Lab, F-31055 Toulouse (France); Maerten, E., E-mail: maerten@chimie.ups-tlse.fr [Université de Toulouse, UPS, and CNRS, LHFA, UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); Remaury, S. [CNES – French Aerospace Agency, 18 Avenue Edouard Belin, F-31401 Toulouse Cedex 9 (France); Solé, S.; Sierra, G. [MAP Coatings – ZI, 2 Rue Clément Ader, 09100 Pamiers (France); Baceiredo, A. [Université de Toulouse, UPS, and CNRS, LHFA, UMR 5069, 118 route de Narbonne, F-31062 Toulouse Cedex 9 (France); Guillaumon, O. [MAP Coatings – ZI, 2 Rue Clément Ader, 09100 Pamiers (France)

    2013-08-15

    Two different space grade silicone rubbers were irradiated by an electron flux of 400 keV. The irradiation impact strongly depends on the chemical structure of rubbers (one reinforced with MQ resins, and the other one functionalized with phenyl groups at the silicon atoms and reinforced with silica). The irradiated rubbers were studied by means of solvent swelling, solid-state {sup 29}Si NMR, and ATR–FTIR spectroscopy. Physical properties were evaluated by thermal (differential scanning calorimetry), mechanical (dynamic mechanical analysis), and thermo-optical (ultraviolet–visible–near infrared spectroscopy) analyses. The formation of silicium T units and Si–CH{sub 2}–Si networks were evidenced by {sup 29}Si NMR, and the increase of the glass transition temperature and of modulus reflect the substantial increase in the macromolecular chain rigidity of the irradiated material. Dramatic damages of mechanical properties were observed, depending on the reinforced materials used. Slight changes of thermo-optical properties were highlighted independently to the initial chemical structure. - Highlights: • Electron flux radiations generate chains cross-linking. • Cross-linking occurs by T and Si–CH{sub 2}–Si units formation. • The cross-linking rate is slightly faster for 2D rubber compared to 3D rubber. • Modulus increases much more significantly for 3D rubber.

  19. The 2-10 keV luminosity as a Star Formation Rate indicator

    CERN Document Server

    Ranalli, P; Setti, G

    2003-01-01

    Radio and far infrared luminosities of star-forming galaxies follow a tight linear relation. Making use of ASCA and BeppoSAX observations of a well-defined sample of nearby star-forming galaxies, we argue that tight linear relations hold between the X-ray, radio and far infrared luminosities. The effect of intrinsic absorption is investigated taking NGC3256 as a test case. It is suggested that the hard X-ray emission is directly related to the Star Formation Rate. Star formation processes may also account for most of the 2-10 keV emission from LLAGNs of lower X-ray luminosities (for the same FIR and radio luminosity). Deep Chandra observations of a sample of radio-selected star-forming galaxies in the Hubble Deep Field North show that the same relation holds also at high (0.2< z< 1.3) redshift. The X-ray/radio relations also allow a derivation of X-ray number counts up to very faint fluxes from the radio Log N-Log S, which is consistent with current limits and models. Thus the contribution of star-formi...

  20. On the spectral hardening at ~> 300 keV in solar flares

    CERN Document Server

    Li, Gang; Zank, Gary; Chen, Yao

    2013-01-01

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

  1. keV fullerene interaction with hydrocarbon targets: Projectile penetration, damage creation and removal

    Energy Technology Data Exchange (ETDEWEB)

    Delcorte, Arnaud [PCPM Laboratory, Universite catholique de Louvain, Croix du Sud 1, B-1348 Louvain-la-Neuve (Belgium)]. E-mail: delcorte@pcpm.ucl.ac.be; Garrison, Barbara J. [Chemistry Department, Pennsylvania State University, University Park, PA (United States)

    2007-02-15

    The physics of energetic fullerene projectile penetration, damage creation and sputtering in organic solids is investigated via molecular dynamics simulations. Two models are used, the first one based on a full atomistic description of the target and the second one, using a coarse-grain prescription that was recently developed and tested for a benzene molecular crystal [E. Smiley, Z. Postawa, I.A. Wojciechowski, N. Winograd, B. J. Garrison, Appl. Surf. Sci. 252 (2006) 6436]. The results explore the mechanism of energy transfer from the C{sub 60} projectile to the organic target atoms/molecules through the comparison with significantly different projectiles (Argon) and samples (Ag crystal). The effects of the projectile energy on the penetration and fast energy transfer processes (200 fs) are also delineated. The second part of the results investigates the 'long term' consequences (20-50 ps) of fullerene impacts in hydrocarbon sample surfaces. In an icosane (C{sub 20}H{sub 42}) solid, a 5 keV C{sub 60} projectile induces a crater of {approx}10 nm diameter surrounded by a {approx}4 nm wide rim and ejects {approx}70 intact molecules. More than 75% of the fragments generated by the fullerene in the surface are also sputtered away by the end of the event. The perspective considers the capabilities of fullerene projectiles for depth profile analysis of molecular samples by particle-induced desorption mass spectrometry.

  2. Optimization of operation parameters of 80-keV electron gun

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jeong Dong; Lee, Yong Deok [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Kang, Heung Sik [Pohang Accelerator Laboratory, Pohang (Korea, Republic of)

    2014-06-15

    A Slowing Down Time Spectrometer (SDTS) system is a highly efficient technique for isotopic nuclear material content analysis. SDTS technology has been used to analyze spent nuclear fuel and the pyro-processing of spent fuel. SDTS requires an external neutron source to induce the isotopic fissile fission. A high intensity neutron source is required to ensure a high for a good fissile fission. The electron linear accelerator system was selected to generate proper source neutrons efficiently. As a first step, the electron generator of an 80-keV electron gun was manufactured. In order to produce the high beam power from electron linear accelerator, a proper beam current is required form the electron generator. In this study, the beam current was measured by evaluating the performance of the electron generator. The beam current was determined by five parameters: high voltage at the electron gun, cathode voltage, pulse width, pulse amplitude, and bias voltage at the grid. From the experimental results under optimal conditions, the high voltage was determined to be 80 kV, the pulse width was 500 ns, and the cathode voltage was from 4.2 V to 4.6 V. The beam current was measured as 1.9 A at maximum. These results satisfy the beam current required for the operation of an electron linear accelerator.

  3. High-resolution 17-75 keV backlighters for high energy density experiments

    Science.gov (United States)

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

    2008-07-01

    17-75keV one- and two-dimensional high-resolution (1017W /cm2. High-resolution point projection one- and two-dimensional radiography has been achieved using microfoil and microwire targets attached to low-Z substrate materials. The microwire size was 10μm×10μm×300μm on a 300μm×300μm×5μm polystyrene substrate. The radiography experiments were performed using the Titan laser at Lawrence Livermore National Laboratory. The results show that the resolution is dominated by the microwire target size and there is very little degradation from the plasma plume, implying that the high-energy x-ray photons are generated mostly within the microwire volume. There are enough Kα photons created with a 300J, 1-ω, 40ps pulse laser from these small volume targets, and that the signal-to-noise ratio is sufficiently high, for single shot radiography experiments. This unique technique will be used on future high energy density experiments at many new high-power laser facilities.

  4. Ionization and fragmentation of cold clusters of PAH molecules - collisions with keV ions

    Science.gov (United States)

    Holm, A. I. S.; Zettergren, H.; Gatchell, M.; Johansson, H. A. B.; Seitz, F.; Schmidt, H. T.; Rousseau, P.; Ławicki, A.; Capron, M.; Domaracka, A.; Lattouf, E.; Maclot, S.; Maisonny, R.; Chesnel, J.-Y.; Manil, B.; Adoui, L.; Huber, B. A.; Cederquist, H.

    2012-11-01

    We discuss the ionization and fragmentation of isolated monomers and cold clusters of polycyclic aromatic hydrocarbon (PAH) molecules in collisions with keV ions in low or high charge states. With low charge state projectile ions, PAH cluster or monomer targets are thermally excited through electronic stopping processes directly in close peripheral or penetrating collisions while only single or few electrons are removed. With high charge state projectiles, electrons are very effectively removed from both the cluster and the monomer target already at very large distances with very little direct target heating. Singly charged and internally very hot PAH monomers are dominant fragmentation products following collisions between Xe20+ ions and PAH clusters. We suggest that this due to an unusually strong dominance of multiple-ionization over single ionization for PAH clusters interacting with highly charged ions. Here, charge and excitation energy is very rapidly redistributed within the clusters before they Coulomb explode and we suggest that these Coulomb explosions induce strong internal heating in the individual PAH molecules. We thus conclude that PAH cluster fragmentation always dominates strongly for all ionization processes regardless if these are due to interactions with ions in high or low charge states. These findings are discussed in view of simple models for cluster evaporation or single and multiple ionizations of PAH clusters.

  5. Radiative neutrino mass and 3.5 keV X-ray line

    CERN Document Server

    Baek, Seungwon

    2015-01-01

    We consider an extension of Zee-Babu model to explain the smallness of neutrino masses. (1) We extend the lepton number symmetry of the original model to local $B-L$ symmetry. (2) We introduce three Dirac dark matter candidates with flavor-dependent $B-L$ charges. After the spontaneous breaking of $B-L$, a discrete symmetry $Z_6$ remains, which guarantees the stability of dark matter. Then the model can explain the 3.5 keV X-ray line signal with decaying dark matter. We also introduce a real scalar field which is singlet under both the SM and $U(1)_{B-L}$ and can explain the current relic abundance of the Dirac fermionic DMs. If the mixing with the SM Higgs boson is small, it does not contribute to DM direct detection. The main contribution to the scattering of DM off atomic nuclei comes from the exchange of $U(1)_{B-L}$ gauge boson, $Z'$, and is suppressed below current experimental bound when $Z'$ mass is heavy ($\\gtrsim 10$ TeV). If the singlet scalar mass is about 0.1--10 MeV, DM self-interaction can be l...

  6. The poker face of the Majoron dark matter model: LUX to keV line

    Energy Technology Data Exchange (ETDEWEB)

    Queiroz, Farinaldo S., E-mail: fdasilva@ucsc.edu [Department of Physics and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, CA 95064 (United States); Sinha, Kuver, E-mail: kusinha@syr.edu [Department of Physics, Syracuse University, Syracuse, NY 13244 (United States)

    2014-07-30

    We study the viability of pseudo Nambu–Goldstone bosons (Majorons) arising in see-saw models as dark matter candidates. Interestingly the stability of the Majoron as dark matter is related to the scale that sets the see-saw and leptogenesis mechanisms, while its annihilation and scattering cross section off nuclei can be set through the Higgs portal. For O(GeV)–O(TeV) Majorons, we compute observables such as the abundance, scattering cross section, Higgs invisible decay width, and emission lines and compare with current data in order to outline the excluded versus still viable parameter space regions. We conclude that the simplest Majoron dark matter models coupling through the Higgs portal, except at the Higgs resonance, are excluded by current direct detection data for Majorons lighter than 225 GeV and future runnings are expected to rule out decisively the 1 GeV–1 TeV window. Lastly, we point out that light keV-scale Majorons whose relic density is set by thermal freeze-in from sterile neutrinos can account for the keV line observed by XMM-Newton observatory in the spectrum of 73 galaxy clusters, within a see-saw model with a triplet Higgs.

  7. THE BEHAVIORS OF 48keV Si IONS IMPLANTED INTO(100)GaAs

    Institute of Scientific and Technical Information of China (English)

    刘惠珍; 曹德新; 等

    1994-01-01

    The behaviors of Si ions implanted into(100)GaAs at liquid nitrogen temperature with energy of 48keV at the doses of 1×1015-5×1015 ions/cm2 has been investigated in this study.The Rutherford backscattering-channeling (RBS-C) combined with particle induced X-ray emission(PIXE) has been used to determine the sites of the Si atoms in the GaAs substrate.The four-point probe was used to measure the resistance of the GaAs before and after Si ions implantation.The experimental results show that Si atoms occupy not only on Ga site but also on As site.The sheet resistivity of GaAs reduced from 1×109Ω/□to 4.5×106Ω/□ after Si ions implanted.and to 4.0×104 Ω/□ after annealing at 850℃ in argon.These results are consistent with some other investigations,for instance,the results of G.Braunstein et al and R.S.Bhattacharya et al.although the implantation condition is not the same.

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

    CERN Document Server

    Naveed, S; Nosych, A; Søby,L

    2013-01-01

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

  9. Excitation of autoionizing states of helium by 100 keV proton impact: theory and experiment

    Energy Technology Data Exchange (ETDEWEB)

    Godunov, A.L.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Benhenni, M.; Bordenave-Montesquieu, A. [Universite Paul Sabatier, Toulouse (France). Laboratoire Collisions, Agregats, Reactivite; Schipakov, V.A. [Troitsk Institute for Innovation and Fusion Research, Moscow (Russian Federation)

    1997-12-14

    A joint theoretical and experimental study of the excitation of the autoionizing (2s{sup 2}){sup 1}S, (2p{sup 2}){sup 1}D and (2s2p){sup 1}P states of helium by 100 keV proton impact is presented for the first time. The role of the three-body Coulomb interaction in the final state between the ejected electron, the scattered proton and the recoil helium ion is emphasized. Calculations have been carried out with inclusion of the three-body Coulomb interaction and within an expansion of a two-electron excitation amplitude in powers of projectile-target interaction up to the second order. A new parametrization is proposed to describe resonance profiles distorted by the Coulomb interaction in the final state (CIFS). New high-resolution (up to 68 meV) measurements of electron emission spectra made it possible to resolve the near-lying (2p{sup 2}){sup 1}D and (2s2p){sup 1}P resonances and reveal an evident distortion of the resonance profiles by CIFS for forward electron ejection angles below 40{sup o}. (author).

  10. Consistency of Hitomi, XMM-Newton and Chandra 3.5 keV data from Perseus

    CERN Document Server

    Conlon, Joseph P; Jennings, Nicholas; Krippendorf, Sven; Rummel, Markus

    2016-01-01

    Hitomi observations of Perseus with the Soft X-ray Spectrometer (SXS) provide a high-resolution look at the 3.5 keV feature reported by multiple groups in the Perseus cluster. The Hitomi spectrum -- which involves the sum of diffuse cluster emission and the point-like central Active Galactic Nucleus (AGN) -- does not show any excess at $E \\sim 3.5 {\\rm keV}$, giving an apparent inconsistency with previous observations of excess diffuse emission. We point out that 2009 Chandra data reveals a strong dip in the AGN spectrum at $E = (3.54 \\pm 0.02) {\\rm keV}$ (cluster frame) -- the identical energy to the diffuse excess observed by XMM-Newton. Scaling this dip to the 2016 AGN luminosity and adding it to the diffuse XMM-Newton excess, this predicts an overall dip in the SXS field of view of $(-7.7 \\pm 4.6) \\times 10^{-6} \\, {\\rm ph} \\, {\\rm cm}^{-2} \\, {\\rm s}^{-1}$ at $E= 3.54$ keV -- a precise match to the Hitomi data when broadened by the dark matter virial velocity. We describe models of Fluorescent Dark Matte...

  11. A New Population of Compton-Thick AGN Identified Using the Spectral Curvature Above 10 keV

    CERN Document Server

    Koss, Michael J; Balokovic, M; Stern, D; Gandhi, P; Lamperti, I; Alexander, D M; Ballantyne, D R; Bauer, F E; Berney, S; Brandt, W N; Comastri, A; Gehrels, N; Harrison, F A; Lansbury, G; Markwardt, C; Ricci, C; Rivers, E; Schawinski, K; Treister, E; Urry, C Megan

    2016-01-01

    We present a new metric that uses the spectral curvature (SC) above 10 keV to identify Compton-thick AGN in low-quality Swift BAT X-ray data. Using NuSTAR, we observe nine high SC-selected AGN. We find that high-sensitivity spectra show the majority are Compton-thick (78% or 7/9) and the remaining two are nearly Compton-thick (NH~5-8x10^23 cm^-2). We find the SC_bat and SC_nustar measurements are consistent, suggesting this technique can be applied to future telescopes. We tested the SC method on well-known Compton-thick AGN and find it is much more effective than broad band ratios (e.g. 100% using SC vs. 20% using 8-24/3-8 keV). Our results suggest that using the >10 keV emission may be the only way to identify this population since only two sources show Compton-thick levels of excess in the OIII to X-ray emission ratio (F_OIII/F_2-10 keV>1) and WISE colors do not identify most of them as AGN. Based on this small sample, we find that a higher fraction of these AGN are in the final merger stage than typical B...

  12. The Complex 0.1-100 keV X-Ray Spectrum of PKS2155-304

    CERN Document Server

    Giommi, P

    1998-01-01

    A long ($>100,000$ seconds) observation of the bright BL Lac object PKS 2155-304 has been carried out with the Narrow Field Instruments of the BeppoSAX satellite as part of the Science Verification Phase. The source was detected between 0.1 and about 100 keV at an intermediate intensity level compared to previous observations. The unique spectral coverage of BeppoSAX has allowed us to detect a number of spectral features. Between 0.1 and 10 keV the spectrum can be well described by a convex spectrum with (energy) slope gradually steepening from 1.1 to 1.6. At higher energies evidence for a sharp spectral hardening is found, while in the soft X-rays (0.1-1.0 keV) some evidence for an absorption feature was found. Indication for an emission line at 6.4 keV in the source rest frame is present. Repeated variability of $\\approx 20-30%$ around the mean flux is clearly detected on time scales of a few hours. From the symmetry and timescale of the observed variations we derive limits on the magnetic field and on the ...

  13. 3.55 keV photon lines from axion to photon conversion in the Milky Way and M31

    CERN Document Server

    Conlon, Joseph P

    2014-01-01

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

  14. Contribution of Unresolved Point Sources to the Diffuse X-ray Background below 1 keV

    CERN Document Server

    Gupta, Anjali

    2009-01-01

    We present here the analysis of X-rays point sources detected in several observations available in the XMM-Newton public archive. We focused, in particular, on energies below 1 keV, which are of particular relevance to the understanding of the Diffuse X-ray Background. The average field of all the exposures is 0.09 deg^-2. We reached an average flux sensitivity of 5.8x10^-16 erg s^-1 cm^-2 in the soft band (0.5-2.0 keV) and 2.5x10^-16 erg s^-1 cm^-2 in the very soft band (0.4-0.6 keV). In this paper we discuss the logN-logS results, the contribution to the integrated X-ray sky flux, and the properties of the cumulative spectrum from all sources. In particular, we found an excess flux at around 0.5 keV in the composite spectrum of faint sources. The excess seems to be a general property of all the fields observed suggesting an additional class of weak sources is contributing to the X-ray emission at these energies. Combining our results with previous investigations we have also quantified the contribution of t...

  15. Hard x-ray broad band Laue lenses (80 - 600 keV): building methods and performances

    CERN Document Server

    Virgilli, E; Rosati, P; Liccardo, V; Squerzanti, S; Carassiti, V; Caroli, E; Auricchio, N; Stephen, J B

    2015-01-01

    We present the status of the laue project devoted to develop a technology for building a 20 meter long focal length Laue lens for hard x-/soft gamma-ray astronomy (80 - 600 keV). The Laue lens is composed of bent crystals of Gallium Arsenide (GaAs, 220) and Germanium (Ge, 111), and, for the first time, the focusing property of bent crystals has been exploited for this field of applications. We show the preliminary results concerning the adhesive employed to fix the crystal tiles over the lens support, the positioning accuracy obtained and possible further improvements. The Laue lens petal that will be completed in a few months has a pass band of 80 - 300 keV and is a fraction of an entire Laue lens capable of focusing X-rays up to 600 keV, possibly extendable down to 20 - 30 keV with suitable low absorption crystal materials and focal length. The final goal is to develop a focusing optics that can improve the sensitivity over current telescopes in this energy band by 2 orders of magnitude.

  16. Large-angle elastic scattering of 88.03-keV photons by elements with 30{<=}Z{<=}92

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Ajay; Shahi, J.S.; Garg, M.L.; Puri, Sanjiv; Mehta, D.; Singh, Nirmal E-mail: nsingh@panjabuniv.chd.nic.in

    2001-10-01

    Elastic-scattering differential cross-sections for 88.03-keV photons have been measured at an angle of 125 deg. for 17 elements in the atomic region 30{<=}Z{<=}92. The measured elastic-scattering cross-sections have been compared with those obtained in the independent-particle approximation through calculations of the modified-relativistic form factors (MFs), a combination of the MFs and angle-independent 'anomalous' scattering factors (ASFs), and the relativistic second-order S-matrix. The S-matrix cross-sections, in general, represent the trend of the measured data over the whole atomic region under investigation. However, these values are, on an average, lower by 10% than the measured ones. The MF cross-sections, in general, exhibit considerable deviations ({approx}30%) from the measured values. In the case of Bi with K-shell binding energy, E{sub K}(Bi)=90.526 keV, just above the incident photon energy (E{sub inc}) of 88.03 keV, the MF cross-section is found to be enormously ({approx}5 times) higher than the measured value. The MF cross-sections in combination with ASFs are in good agreement with the measured values for all the elements except for Pb (E{sub K}(Pb)=88.004 keV) and Bi, where these values are enormously ({approx}28 times) smaller and higher by 31%, respectively.

  17. Non-dissociative and dissociative ionisation of H sub 2 by 50-2000 keV antiprotons

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, L.H.; Hvelplund, P.; Knudsen, H.; Moeller, S.P.; Pedersen, J.O.P.; Tang-Petersen, S.; Uggerhoej, E. (Aarhus Univ. (Denmark). Inst. of Physics); Elsener, K. (European Organization for Nuclear Research, Geneva (Switzerland)); Morenzoni, E. (Paul Scherrer Inst. (PSI), Villigen (Switzerland))

    1990-08-14

    A beam of antiprotons with energies between 50 keV and 2 MeV has been used for measurements of non-dissociative ionisation and dissociative ionisation cross sections of H{sub 2}. The results are compared with cross sections for equivelocity protons and electrons, and the role of interference effects in two-electron processes is discussed. (author).

  18. Energy Reflection Coefficients for 5-10 keV He Ions Incident on Au, Ag, and Cu

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.; Littmark, U.

    1978-01-01

    The calorimetric deuterium-film method was used for measurements of the energy reflection coefficient γ for normal incidence of 5-10 keV He ions on Cu, Ag and Au. A theoretical calculation of γ by means of transport theory gives fair agreement with the experimental results. The experimental data ...

  19. A 7.2 keV spherical crystal backlighter system for Sandia's Z Pulsed Power Facility

    Science.gov (United States)

    Schollmeier, M.; Knapp, P. F.; Ampleford, D. J.; Loisel, G. P.; Robertson, G.; Shores, J. E.; Smith, I. C.; Speas, C. S.; Porter, J. L.; McBride, R. D.

    2016-10-01

    Many experiments on Sandia's Z facility, a 30 MA, 100 ns rise-time, pulsed-power driver, use a monochromatic Quartz crystal imaging backlighter system at 1.865 keV (Si Heα) or 6.151 keV (Mn Heα) x-ray energy to radiograph an imploding liner (cylindrical tube) or wire array. The x-ray source is generated by the Z-Beamlet Laser (ZBL), which provides up to 4.5 kJ at 527 nm during a 6 ns window. Radiographs of an imploding thick-walled Beryllium liner at a convergence ratio of about 20 [CR =Rin . (0) /Rin . (t) ] were too opaque to identify the inner surface of the liner with high confidence, demonstrating the need for a higher-energy x-ray backlighter between 6 and 10 keV. We present the design, test and first application of a Ge (335) spherical crystal x-ray backlighter system using the 7.242 keV Co Heα resonance line. The system operates at an almost identical Bragg angle as the existing 1.865 and 6.151 keV backlighters, enhancing our capabilities such as two-color, two-frame radiography, without changing detector shielding hardware. SAND No: SAND2016-6724 A. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corp., a wholly owned subsidiary of Lockheed Martin Corp., for the U.S. DoE NNSA under contract DE-AC04-94AL85000.

  20. Imaging X-ray detector front-end with high dynamic range: IDeF-X HD

    Energy Technology Data Exchange (ETDEWEB)

    Gevin, O.; Lemaire, O.; Lugiez, F. [CEA, Irfu, Service d' Electronique, de Detecteurs et d' Informatique, Bat. 141, F-91191 Gif-sur-Yvette (France); Michalowska, A., E-mail: alicja.michalowska@cea.fr [CEA, Irfu, Service d' Electronique, de Detecteurs et d' Informatique, Bat. 141, F-91191 Gif-sur-Yvette (France); Baron, P. [CEA, Irfu, Service d' Electronique, de Detecteurs et d' Informatique, Bat. 141, F-91191 Gif-sur-Yvette (France); Limousin, O. [CEA, Irfu, Service d' Astrophysique, Bat. 709 Orme des Merisiers, F-91191 Gif-sur-Yvette (France); Delagnes, E. [CEA, Irfu, Service d' Electronique, de Detecteurs et d' Informatique, Bat. 141, F-91191 Gif-sur-Yvette (France)

    2012-12-11

    Presented circuit, IDeF-X HD (Imaging Detector Front-end) is a member of the IDeF-X ASICs family for space applications. It has been optimized for a half millimeter pitch CdTe or CdZnTe pixelated detector arranged in 16 Multiplication-Sign 16 array. It is aimed to operate in the hard X-ray range from few keV up to 250 keV or more. The ASIC has been realized in AMS 0.35 {mu}m CMOS process. The IDeF-X HD is a 32 channel analog front-end with self-triggering capability. The architecture of the analog channel includes a chain of charge sensitive amplifier with continuous reset system and non-stationary noise suppressor, adjustable gain stage, pole-zero cancellation stage, adjustable shaping time low pass filter, baseline holder and peak detector with discriminator. The power consumption of the IDeF-X HD is 800 {mu}W per channel. With the in-channel variable gain stage the nominal 250 keV dynamic range of the ASIC can be extended up to 1 MeV anticipating future applications using thick sensors. Measuring the noise performance without a detector at the input with minimized leakage current (programmable) at the input, we achieved ENC of 33 electrons rms at 10.7 {mu}s peak time. Measurements with CdTe detector show good energy resolution FWHM of 1.1 keV at 60 keV and 4.3 keV at 662 keV with detection threshold below 4 keV. In addition, an absolute temperature sensor has been integrated with resolution of 1.5 Degree-Sign C.

  1. Imaging X-ray detector front-end with high dynamic range: IDeF-X HD

    Science.gov (United States)

    Gevin, O.; Lemaire, O.; Lugiez, F.; Michalowska, A.; Baron, P.; Limousin, O.; Delagnes, E.

    2012-12-01

    Presented circuit, IDeF-X HD (Imaging Detector Front-end) is a member of the IDeF-X ASICs family for space applications. It has been optimized for a half millimeter pitch CdTe or CdZnTe pixelated detector arranged in 16×16 array. It is aimed to operate in the hard X-ray range from few keV up to 250 keV or more. The ASIC has been realized in AMS 0.35 μm CMOS process. The IDeF-X HD is a 32 channel analog front-end with self-triggering capability. The architecture of the analog channel includes a chain of charge sensitive amplifier with continuous reset system and non-stationary noise suppressor, adjustable gain stage, pole-zero cancellation stage, adjustable shaping time low pass filter, baseline holder and peak detector with discriminator. The power consumption of the IDeF-X HD is 800 μW per channel. With the in-channel variable gain stage the nominal 250 keV dynamic range of the ASIC can be extended up to 1 MeV anticipating future applications using thick sensors. Measuring the noise performance without a detector at the input with minimized leakage current (programmable) at the input, we achieved ENC of 33 electrons rms at 10.7 μs peak time. Measurements with CdTe detector show good energy resolution FWHM of 1.1 keV at 60 keV and 4.3 keV at 662 keV with detection threshold below 4 keV. In addition, an absolute temperature sensor has been integrated with resolution of 1.5 °C.

  2. Temperature-tuned Maxwell-Boltzmann neutron spectra for kT ranging from 30 up to 50 keV for nuclear astrophysics studies.

    Science.gov (United States)

    Martín-Hernández, G; Mastinu, P F; Praena, J; Dzysiuk, N; Capote Noy, R; Pignatari, M

    2012-08-01

    The need of neutron capture cross section measurements for astrophysics motivates present work, where calculations to generate stellar neutron spectra at different temperatures are performed. The accelerator-based (7)Li(p,n)(7)Be reaction is used. Shaping the proton beam energy and the sample covering a specific solid angle, neutron activation for measuring stellar-averaged capture cross section can be done. High-quality Maxwell-Boltzmann neutron spectra are predicted. Assuming a general behavior of the neutron capture cross section a weighted fit of the spectrum to Maxwell-Boltzmann distributions is successfully introduced.

  3. Optical constants in the hard x-ray/soft gamma-ray range

    DEFF Research Database (Denmark)

    Cooper-Jensen, Carsten P.; Brejnholt, Nicolai; Romaine, S.

    2008-01-01

    Future astrophysics missions operating in the hard X-ray/Soft Gamma ray range is slated to carry novel focusing telescopes based on the use of depth graded multilayer reflectors. Current design studies show that, at the foreseen focal lengths, it should be feasible to focus X-rays at energies...... as high as 300 keV. These designs use extrapolations of theoretical and experimentally determined optical constants below 100 keV. We have previously shown that determining the optical constants from traditional single layer film above 40 keV is very difficult. One needs to have substrates which are very...... and compare these to theoretically calculated values and previous experiments....

  4. Diagnostics for the optimization of an 11 keV inverse Compton scattering x-ray source

    Energy Technology Data Exchange (ETDEWEB)

    Chauchat, A.-S.; Brasile, J.-P [Thales Communications and Security, 4 avenue des Louvresses 92230 Gennevilliers (France); Le Flanchec, V.; Negre, J.-P.; Binet, A. [CEA DAM DIF, Bruyeres-le-Chatel 91290 Arpajon (France); Ortega, J.-M. [LCP Universite Paris-Sud, Bat. 201, 91405 Orsay (France)

    2013-04-19

    In a scope of a collaboration between Thales Communications and Security and CEA DAM DIF, 11 keV Xrays were produced by inverse Compton scattering on the ELSA facility. In this type of experiment, X-ray observation lies in the use of accurate electron and laser beam interaction diagnostics and on fitted X-ray detectors. The low interaction probability between < 100 {mu}m width, 12 ps [rms] length electron and photon pulses requires careful optimization of pulse spatial and temporal covering. Another issue was to observe 11 keV X-rays in the ambient radioactive noise of the linear accelerator. For that, we use a very sensitive detection scheme based on radio luminescent screens.

  5. Improved energy of the 21.5 keV M1 + E2 nuclear transition in {sup 151}Eu

    Energy Technology Data Exchange (ETDEWEB)

    Inoyatov, A.Kh. [JINR, Laboratory of Nuclear Problems, Dubna, Moscow Region (Russian Federation); National University, Institute of Applied Physics, Tashkent (Uzbekistan); Kovalik, A. [JINR, Laboratory of Nuclear Problems, Dubna, Moscow Region (Russian Federation); Nuclear Physics Institute of the ASCR, Rez near Prague (Czech Republic); Filosofov, D.V.; Perevoshchikov, L.L. [JINR, Laboratory of Nuclear Problems, Dubna, Moscow Region (Russian Federation); Rysavy, M. [Nuclear Physics Institute of the ASCR, Rez near Prague (Czech Republic); Baimukhanova, A. [JINR, Laboratory of Nuclear Problems, Dubna, Moscow Region (Russian Federation); Institute of Nuclear Physics, Almaty (Kazakhstan)

    2016-05-15

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

  6. Miten eri sidosryhmät näkevät sähköauton tulevaisuuden Loviisassa?

    OpenAIRE

    Waltonen, Peter

    2014-01-01

    Tämän opinnäytetyön tarkoitus on tutkia miten eri sidosryhmät näkevät sähköauton tulevaisuuden Loviisassa. Loviisan kaupunki on keväällä asentamassa ensimmäistä latauspistettä ja kaupunki haluaa saada enemmän tietoja latauspisteistä ennen asentamista. Opinnäytetyöstäni Loviisan kaupunki saa informaatiota sähköautoista sekä latauslaitteista. Tutkimuksessa olen tehnyt toimintaympäristöanalyysin. Kysyntäanalyysissä tarkastin nykyistä kysyntätilannetta sekä markkinapotentiaalia. Tällä hetkellä Su...

  7. Heavy concerns about the light axino explanation of the 3.5 keV X-ray line

    Directory of Open Access Journals (Sweden)

    Stefano Colucci

    2015-11-01

    Full Text Available An unidentified 3.5 keV line from X-ray observations of galaxy clusters has been reported recently. Although still under scrutiny, decaying dark matter could be responsible for this signal. We investigate whether an axino with a mass of 7 keV could explain the line, keeping the discussion as model independent as possible. We point out several obstacles, which were overlooked in the literature, and which make the axino an unlikely candidate. The only viable scenario predicts a light metastable neutralino, with a mass between 0.1 and 10 GeV and a lifetime between 10−3 and 104 s.

  8. First measurement of the 14N(p,gamma)15O cross section down to 70 keV

    CERN Document Server

    Lemut, A; Confortola, F; Bonetti, R; Broggini, C; Corvisiero, P; Costantini, H; Cruz, J; Formicola, A; Fülöp, Z; Gervino, G; Guglielmetti, A; Gustavino, C; Gyürky, G; Imbriani, G; Jesus, A P; Junker, M; Limata, B; Menegazzo, R; Prati, P; Roca, V; Rogalla, D; Rolfs, C; Romano, M; Alvarez, C R; Schumann, F; Somorjai, E; Straniero, O; Strieder, F; Terrasi, F; Trautvetter, H P; Fulop, Zs.; Gyurky, Gy.

    2006-01-01

    In stars with temperatures above 20*10^6 K, hydrogen burning is dominated by the CNO cycle. Its rate is determined by the slowest process, the 14N(p,gamma)15O reaction. Deep underground in Italy's Gran Sasso laboratory, at the LUNA 400 kV accelerator, the cross section of this reaction has been measured at energies much lower than ever achieved before. Using a windowless gas target and a 4pi BGO summing detector, direct cross section data has been obtained down to 70 keV, reaching a value of 0.24 picobarn. The Gamow peak has been covered by experimental data for several scenarios of stable and explosive hydrogen burning. In addition, the strength of the 259 keV resonance has been remeasured. The thermonuclear reaction rate has been calculated for temperatures 90 - 300 *10^6 K, for the first time with negligible impact from extrapolations.

  9. Miten eri sidosryhmät näkevät sähköauton tulevaisuuden Loviisassa?

    OpenAIRE

    Waltonen, Peter

    2014-01-01

    Tämän opinnäytetyön tarkoitus on tutkia miten eri sidosryhmät näkevät sähköauton tulevaisuuden Loviisassa. Loviisan kaupunki on keväällä asentamassa ensimmäistä latauspistettä ja kaupunki haluaa saada enemmän tietoja latauspisteistä ennen asentamista. Opinnäytetyöstäni Loviisan kaupunki saa informaatiota sähköautoista sekä latauslaitteista. Tutkimuksessa olen tehnyt toimintaympäristöanalyysin. Kysyntäanalyysissä tarkastin nykyistä kysyntätilannetta sekä markkinapotentiaalia. Tällä hetkellä Su...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-09-15

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

  11. Spatial and Temporal Variations of the Diffuse Iron 6.4 keV Line in the Galactic Center Region

    CERN Document Server

    Chernyshov, D O; Nobukawa, M; Tsuru, T G; Koyama, K; Uchiyama, H; Matsumoto, H

    2011-01-01

    We analyze the diffuse Fe I K-alpha line generated in the diffuse interstellar molecular hydrogen by primary photons or subrelativistic protons injected by Sagittarius (Sgr) A*. We showed that unlike emission from compact molecular clouds, this emission can be permanently observed in the directions of the Galactic center. We conclude that the diffuse emission of 6.4 keV line observed at present is probably due to Fe I K-alpha vacancy production by primary photons if the X-ray luminosity of Sgr A* was about Lx ~ 10^39-10^40 erg/s. In principle these data can also be described in the framework of the model when the 6.4 keV line emission is generated by subrelativistic protons generated by accretion onto the central black hole but in this case extreme parameters of this model are necessary.

  12. Electron-positron pair production near the Galactic Centre and the 511 keV emission line

    CERN Document Server

    Chan, Man Ho

    2015-01-01

    Recent observations indicate that a high production rate of positrons (strong 511 keV line) and a significant amount of excess GeV gamma-ray exist in our Galactic bulge. The latter issue can be explained by $\\sim 40$ GeV dark matter annihilation through $b \\bar{b}$ channel while the former one remains a mystery. On the other hand, recent studies reveal that a large amount of high density gas might exist near the Galactic Centre million years ago to account for the young, massive stars extending from 0.04 pc - 7 pc. In this article, I propose a new scenario and show that the 40 GeV dark matter annihilation model can also explain the required positron production rate (511 keV line) in the bulge due to the existence of the high density gas cloud near the supermassive black hole long time ago.

  13. GRIS detection of Al-26 1809 keV line emission from the Galactic center region as a broad line

    Science.gov (United States)

    Naya, Juan E.; Barthelmy, Scott D.; Bartlett, Lyle M.; Gehrels, Neil; Leventhal, Marvin; Parsons, Ann; Teegarden, Bonnard J.; Tueller, Jack

    1997-01-01

    The gamma ray imaging spectrometer (GRIS) was used to observe the 1809 keV emission from the Galactic center region. The observed line is broader than the instrument resolution. The measured intrinsic width is 5.4 +/- 1.4 keV full width half medium, which is more than three times the maximum Doppler broadening expected due to Galactic rotation. The detection of such a wide feature, suggesting a high dispersion velocity has implications for the origin of Galactic Al-26. It suggests a supernova explosion origin or a Wolf-Rayet stellar wind origin of Al-26. The fact that the Al-26 has not come to rest after 10(exp 6) years presents a challenge to the current understanding of the Al-26 production and propagation in the Galaxy.

  14. Development of a 110-m-mA, 75-keV proton injector for high-current, CW linacs

    Energy Technology Data Exchange (ETDEWEB)

    Sherman, J.D.; Bolme, G.O.; Hansborough, L.D. [and others

    1996-09-01

    A dc proton injector is being developed for a 6.7 MeV CW RFQ at Los Alamos. The RFQ input beam requirements are 75 keV energy, 110 mA dc proton current, and 0.20 {pi}mm-mrad rms normalized emittance. The injector has now produced a 75-keV, 117-mA dc proton beam (130 mA total current) with the required emittance. The emittance has been measured after a 2.1 m long two-solenoid beam transport system. The measured emittance can be explained in terms of the ion source emittance and beam transport through the focusing elements. Measured proton fractions are 90-92% of the beam current. Engineering of the accelerating column high-voltage design is being improved to increase the injector reliability. Injector design details and status are presented.

  15. νR Dark matter-philic Higgs for 3.5 keV X-ray signal

    Directory of Open Access Journals (Sweden)

    Naoyuki Haba

    2015-04-01

    Full Text Available We suggest a new model of 7 keV right-handed neutrino dark matter inspired by a recent observation of 3.5 keV X-ray line signal in the XMM-Newton observatory. It is difficult to derive the tiny masses with a suitable left–right mixing of the neutrino in a framework of ordinary simple type-I seesaw mechanism. We introduce a new Higgs boson, a dark matter-philic Higgs boson, in which the smallness of its vacuum expectation value can be achieved. We investigate suitable parameter regions where the observed dark matter properties are satisfied. We find that the vacuum expectation value of dark matter-philic Higgs boson should be about 0.17 GeV.

  16. Nustar and Chandra insight into the nature of the 3-40 kev nuclear emission in NGC 253

    DEFF Research Database (Denmark)

    Lehmer, B. D.; Wik, D. R.; Hornschemeier, A. E.;

    2013-01-01

    We present results from three nearly simultaneous Nuclear Spectroscopic Telescope Array ( NuSTAR ) and Chandra monitoring observations between 2012 September 2 and 2012 November 16 of the local star-forming galaxy NGC 253. The 3-40 keV intensity of the inner ~ 20 arcsec ( ~ 400 pc) nuclear region......, as measured by NuSTAR , varied by a factor of ~ 2 across the three monitoring observations. The Chandra data reveal that the nuclear region contains three bright X-ray sources, including a luminous ( L2-10 keV ~ few × 1039 erg s-1 ) point source located ~ 1 arcsec from the dynamical center of the galaxy...... nature for this source. Future NuSTAR and Chandra monitoring would be well equipped to break the degeneracy between the AGN and ULX nature of the 2003 source, if again caught in a high state....

  17. State-resolved study of keV sputtered neutral atoms by resonance ionization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    He, C.; Postawa, Z.; Rosencrance, S.; Chatterjee, R.; Garrison, B.J.; Winograd, N. [Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    1995-04-01

    We have performed simultaneous measurements of energy-, and angle-resolved distributions of Ni atoms desorbed from a single crystal Ni{l_brace}100{r_brace} surface bombarded by 5 keV Ar{sup +} ions. Ground state and six low-lying excited states from the {ital a}{sup 3}{ital F}{sub {ital J}} ({ital J}=4,3,2) and {ital a}{sup 3}{ital D}{sub {ital J}} ({ital J}=3,2,1) manifolds as well as {ital a}{sup 1}{ital D}{sub 2} have been investigated along different azimuths. Both {ital a}{sup 3}{ital F}{sub {ital J}} and {ital a}{sup 1}{ital D}{sub 2} states have closed shell electronic structure, 3{ital d}{sup 8}4{ital s}{sup 2}, while the {ital a}{sup 3}{ital D}{sub {ital J}} states are open shell electronic states, 3{ital d}{sup 9}4{ital s}{sup 1}. Angle-integrated energy distributions demonstrate a strong dependence on the electronic structure while the magnitude of the excitation energy does not significantly alter the results. This is the first conclusive evidence that electronic structure rather than excitation energy is the primary factor in determining kinetic energy distributions of sputtered neutral species. Population distribution among the seven electronic states are obtained through two sets of measurements performed on two experimental apparati: one measures the energy- and angle-integrated resonance ionization signal intensities of the sputtered Ni; the other measures the resonance ionization signal intensities of thermally evaporated Ni atoms with a known heating temperature. The experiment results show that the population distribution is very different from Boltzman-type distribution with {ital a}{sup 3}{ital D}{sub 3} and {ital a}{sup 3}{ital D}{sub 2} states more intensely populated. The work also illustrates the power of RIS to perform quantum state specific measurements on fast moving atoms. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

  18. Self-attenuation correction factors for bioindicators measured by gamma spectrometry for energies <100keV

    Energy Technology Data Exchange (ETDEWEB)

    Manduci, L., E-mail: manduci@orange.f [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); Tenailleau, L. [GEA, Groupe d' Etudes Atomiques, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); Trolet, J.L. [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); De Vismes, A. [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France); IRSN/DEI/STEME/LMRE, Bois des Rames Bt 501, 91400 Orsay (France); Lopez, G.; Piccione, M. [EAMEA, Ecole des Applications Militaires de l' Energie Atomique, Bureau Courrier Regional Marine Cherbourg cc19, 50115 Cherbourg-Octeville (France)

    2010-01-21

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

  19. Scheme to increase the output average spectral flux of the European XFEL at 14.4 keV

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2015-08-15

    Techniques like inelastic X-ray scattering (IXS) and nuclear resonance scattering (NRS) are currently limited by the photon flux available at X-ray sources. At 14.4 keV, third generation synchrotron radiation sources produce a maximum of 10{sup 10} photons per second in a meV bandwidth. In this work we discuss about the possibility of increasing this flux a thousand-fold by exploiting high repetition rate self-seeded pulses at the European XFEL. Here we report on a feasibility study for an optimized configuration of the SASE2 beamline at the European XFEL which combines self-seeding and undulator tapering techniques in order to increase the average spectral flux at 14.4 keV. In particular, we propose to perform monochromatization at 7.2 keV with the help of self-seeding, and amplify the seed in the first part of output undulator. The amplification process can be stopped at a position well before saturation, where the electron beam gets considerable bunching at the 2nd harmonic of the coherent radiation. A second part of the output undulator follows, tuned to the 2nd harmonic frequency, i.e. at 14.4 keV and is used to obtain saturation at this energy. One can further prolong the exchange of energy between the photon and the electron beam by tapering the last part of the output undulator. We performed start-to-end simulations and demonstrate that self-seeding, combined with undulator tapering, allows one to achieve more than a hundred-fold increase in average spectral flux compared with the nominal SASE regime at saturation, resulting in a maximum flux of order 10{sup 13} photons per second in a meV bandwidth.

  20. Position resolution limits in pure noble gaseous detectors for X-ray energies from 1 to 60 keV

    Directory of Open Access Journals (Sweden)

    C.D.R. Azevedo

    2015-02-01

    Full Text Available The calculated position resolutions for X-ray photons (1–60 keV in pure noble gases at atmospheric pressure are presented. In this work we show the influence of the atomic shells and the detector dimensions on the intrinsic position resolution of the used noble gas. The calculated results were obtained by using a new software tool, Degrad, and compared to the available experimental data.

  1. Astrophysical S factor for the B-11(d, n)C-12 reaction below 135 keV

    NARCIS (Netherlands)

    Parpottas, Y.; Ahmed, M. W.; Blackston, M. A.; France, R. H.; Perdue, B. A.; Prior, R. M.; Sabourov, A.; Spraker, M. C.; Weller, H. R.

    2006-01-01

    The B-11(d,n)C-12 reaction was studied using deuteron beams of 120-160 keV to determine the absolute astrophysical S factors and cross sections for the n(0) and n(1) neutron groups. The slopes of the S factors are consistent with zero for both the n(0) and n(1) cases. The measured S factor for the s

  2. Vaatemerkin brändin vahvistaminen promootiovideon avulla : Case: Uhana Design Kevät / Kesä 2016 -mallisto

    OpenAIRE

    Vasara, Rosa

    2016-01-01

    Opinnäytetyö käsittelee promootiovideon suunnittelua suomalaiselle vaatemerkille. Opinnäytetyön toimeksiantaja on tamperelainen Uhana Design, jolle suunnittelin ja toteutin sosiaalisessa mediassa julkaistavan Kevät Kesä 2016 -malliston promootiovideon. Tavoitteena on tuottaa Uhana Designille uutta ja brändin arvoa kasvattavaa markkinointimateriaalia. Kirjallisessa osassa tutkin digitaalista markkinointia ja luksusbrändin ominaisuuksia, jotka tukevat brändin arvoa lisäävää digitaalisen mar...

  3. The First MAXI/SSC Catalog of X-ray Sources in 0.7--7.0~keV

    CERN Document Server

    Tomida, Hiroshi; Tsunemi, Hiroshi; Imatani, Ritsuko; Kimura, Masashi; Nakahira, Satoshi; Hanayama, Takanori; Yoshidome, Koshiro

    2016-01-01

    We present the first source catalog of the Solid-state Slit Camera (SSC) of the Monitor of All-sky X-ray Image (MAXI) mission on the International Space Station, using the 45-month data from 2010 August to 2014 April in 0.7--7.0~keV bands. Sources are searched for in two energy bands, 0.7--1.85~keV (soft) and 1.85--7.0~keV (hard), the limiting sensitivity of 3 and 4~mCrab are achieved and 140 and 138 sources are detected in the soft and hard energy bands, respectively. Combining the two energy bands, 170 sources are listed in the MAXI/SSC catalog. All but 2 sources are identified with 22 galaxies including AGNs, 29 cluster of galaxies, 21 supernova remnants, 75 X-ray binaries, 8 stars, 5 isolated pulsars, and 9 non-categorized objects. Comparing the soft-band fluxes at the brightest end in our catalog with the ROSAT survey, which was performed about 20 years ago, 10\\% of the cataloged sources are found to have changed the flux since the ROSAT era.

  4. Scheme to increase the output average spectral flux of the European XFEL at $14.4$ keV

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2015-01-01

    Techniques like inelastic X-ray scattering (IXS) and nuclear resonance scattering (NRS) are currently limited by the photon flux available at X-ray sources. At $14.4$ keV, third generation synchrotron radiation sources produce a maximum of $10^{10}$ photons per second in a meV bandwidth. In this work we discuss about the possibility of increasing this flux a thousand-fold by exploiting high repetition rate self-seeded pulses at the European XFEL. Here we report on a feasibility study for an optimized configuration of the SASE2 beamline at the European XFEL which combines self-seeding and undulator tapering techniques in order to increase the average spectral flux at $14.4$ keV. In particular, we propose to perform monochromatization at $7.2$ keV with the help of self-seeding, and amplify the seed in the first part of output undulator. The amplification process can be stopped at a position well before saturation, where the electron beam gets considerable bunching at the 2nd harmonic of the coherent radiation. ...

  5. Active detection of small quantities of shielded highly-enriched uranium using low-dose 60-kev neutron interrogation

    Science.gov (United States)

    Kerr, Phil; Rowland, Mark; Dietrich, Dan; Stoeffl, Wolfgang; Wheeler, Boyd; Nakae, Les; Howard, Doug; Hagmann, Chris; Newby, Jason; Porter, Robert

    2007-08-01

    Active interrogation with low-energy neutrons provides a search technique for highly-enriched uranium concealed in cargo. We describe the technique and show initial results using a low-dose 60-keV neutron beam. This technique produces a clear induced fission signal in the presence of small quantities of 235U. The technique has been validated with low-Z and high-Z cargo materials. The technique uses a forward-directed beam of 60-keV neutrons to induce fission in 235U. Detection of the fast fission neutrons with pulse-shape discriminating scintillators is then the signature for 235U. The beam of neutrons is generated with a 1.93 MeV proton beam impinging on a natural lithium target. The proton beam is produced by a radio-frequency quadrupole LINAC. The 60 keV neutron beam is forward-directed because the 7Li(p, n) reaction is just above threshold for a proton energy of 1.93 MeV.

  6. Galaxy Clusters in the Swift/BAT era II: 10 more Clusters detected above 15 keV

    Energy Technology Data Exchange (ETDEWEB)

    Ajello, M.; /SLAC /KIPAC, Menlo Park; Rebusco, P.; /KIPAC, Menlo Park; Cappelluti, N.; /Garching, Max Planck Inst., MPE /Maryland U., Baltimore County; Reimer, O.; /SLAC /Palermo Observ.; Boehringer, H.; /Garching, Max Planck Inst., MPE; La Parola, V.; Cusumano, G.; /Palermo Observ.

    2010-10-27

    We report on the discovery of 10 additional galaxy clusters detected in the ongoing Swift/BAT all-sky survey. Among the newly BAT-discovered clusters there are: Bullet, Abell 85, Norma, and PKS 0745-19. Norma is the only cluster, among those presented here, which is resolved by BAT. For all the clusters we perform a detailed spectral analysis using XMM-Newton and Swift/BAT data to investigate the presence of a hard (non-thermal) X-ray excess. We find that in most cases the clusters emission in the 0.3-200 keV band can be explained by a multi-temperature thermal model confirming our previous results. For two clusters (Bullet and Abell 3667) we find evidence for the presence of a hard X-ray excess. In the case of the Bullet cluster, our analysis confirms the presence of a non-thermal, power-law like, component with a 20-100 keV flux of 3.4 x 10{sup -12} erg cm{sup -2} s{sup -1} as detected in previous studies. For Abell 3667 the excess emission can be successfully modeled as a hot component (kT = {approx}13 keV). We thus conclude that the hard X-ray emission from galaxy clusters (except the Bullet) has most likely thermal origin.

  7. FLUKA and PENELOPE simulations of 10 keV to 10 MeV photons in LYSO and soft tissue

    Science.gov (United States)

    Chin, M. P. W.; Böhlen, T. T.; Fassò, A.; Ferrari, A.; Ortega, P. G.; Sala, P. R.

    2014-02-01

    Monte Carlo simulations of electromagnetic particle interactions and transport by FLUKA and PENELOPE were compared. 10 keV to 10 MeV incident photon beams impinged a LYSO crystal and a soft-tissue phantom. Central-axis as well as off-axis depth doses agreed within 1 s.d.; no systematic under- or over-estimate of the pulse height spectra was observed from 100 keV to 10 MeV for both materials, agreement was within 5%. Simulation of photon and electron transport and interactions at this level of precision and reliability is of significant impact, for instance, on treatment monitoring of hadrontherapy where a code like FLUKA is needed to simulate the full suite of particles and interactions (not just electromagnetic). At the interaction-by-interaction level, apart from known differences in condensed history techniques, two-quanta positron annihilation at rest was found to differ between the two codes. PENELOPE produced a 511 keV sharp line, whereas FLUKA produced visible acolinearity, a feature recently implemented to account for the momentum of shell electrons.

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

    Science.gov (United States)

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

    2014-05-01

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

  9. Tracking Down the Source Population Responsible for the Unresolved Cosmic 6-8 keV Background

    CERN Document Server

    Xue, Y Q; Brandt, W N; Luo, B; Alexander, D M; Bauer, F E; Comastri, A; Fabian, A C; Gilli, R; Lehmer, B D; Schneider, D P; Vignali, C; Young, M

    2012-01-01

    Using the 4 Ms Chandra Deep Field-South (CDF-S) survey, we have identified a sample of 6845 X-ray undetected galaxies that dominates the unresolved ~ 20-25% of the 6-8 keV cosmic X-ray background (XRB). This sample was constructed by applying mass and color cuts to sources from a parent catalog based on GOODS-South HST z-band imaging of the central 6'-radius area of the 4 Ms CDF-S. The stacked 6-8 keV detection is significant at the 3.9 sigma level, but the stacked emission was not detected in the 4-6 keV band which indicates the existence of an underlying population of highly obscured active galactic nuclei (AGNs). Further examinations of these 6845 galaxies indicate that the galaxies on the top of the blue cloud and with redshifts of 1 ~1E10 M_sun) galaxies. We discuss constraints upon this underlying AGN population, supporting evidence for relatively low-mass galaxies hosting highly obscured AGNs, and prospects for further boosting the stacked signal.

  10. Galaxy Clusters in the Swift/BAT era II: 10 more Clusters detected above 15 keV

    CERN Document Server

    Ajello, M; Cappelluti, N; Reimer, O; Boehringer, H; La Parola, V; Cusumano, G

    2010-01-01

    We report on the discovery of 10 additional galaxy clusters detected in the ongoing Swift/BAT all-sky survey. Among the newly BAT-discovered clusters there are: Bullet, Abell 85, Norma, and PKS 0745-19. Norma is the only cluster, among those presented here, which is resolved by BAT. For all the clusters we perform a detailed spectral analysis using XMM-Newton and Swift/BAT data to investigate the presence of a hard (non-thermal) X-ray excess. We find that in most cases the clusters' emission in the 0.3-200keV band can be explained by a multi-temperature thermal model confirming our previous results. For two clusters (Bullet and Abell 3667) we find evidence for the presence of a hard X-ray excess. In the case of the Bullet cluster, our analysis confirms the presence of a non-thermal, power-law like, component with a 20-100 keV flux of 3.4 \\times 10-12 erg cm-2 s-1 as detected in previous studies. For Abell 3667 the excess emission can be successfully modeled as a hot component (kT=~13keV). We thus conclude tha...

  11. Excitation of the helium autoionizing states in He/sup +/+He collisions, between 3 and 140 keV

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Gleizes, A.; Benoit-Cattin, P.

    1982-01-01

    The autoionization of the helium atom has been experimentally studied in He/sup +/+He collisions between 3 and 140 keV by electron spectrometry. The excitation of the two collision partners has been considered. Above 10 keV, the shapes and excitation cross sections of the 2s/sup 2/ /sup 1/S, 2s2p /sup 3/P, 2p/sup 2/ /sup 1/D, and 2s2p /sup 1/P are determined by a numerical fitting procedure which is reported in detail; below 10 keV the (/sup 1/D+/sup 1/P), and 2p/sup 2/ /sup 1/S line intensities are obtained by planimetry since important post-collision effects are observed. From the angular distributions measured below 15 keV, the relative sublevel populations are deduced for the 2p/sup 2/ /sup 1/D and 2s2p/sup 1/ P levels and are compared with those obtained by other authors in a coincidence experiment; the excitation processes are then discussed within the quasimolecular-excitation model. For the highest collision energies, the asymmetry of the angular distributions with respect to 90 /sup 0/ as well as the line shapes above 100 keV are interpreted by the occurrence of sudden electronic transitions to the continuum. A comparison of the differential cross sections for emission of electrons by autoionization of the fast and slow particles permits us to show that the quasimolecule model cannot explain what is observed above a collision velocity of about 0.5 a.u. The dependence of the total cross sections against the collision energy is also discussed in terms of an evolution of the excitation mechanism from a quasimolecular to an atomic one; the specific variation of the 2s2p /sup 3/P cross section strengthens this interpretation. These total cross sections are compared with those estimated from earlier H/sup +/+He data published by us; similar autoionization cross-section values are expected for the two systems at high collision velocity.

  12. à la capture de radicaux sous irradiation X à 1,5 keV

    Directory of Open Access Journals (Sweden)

    Khalil Talat Tariq

    2016-01-01

    Full Text Available L’environnement chimique de l’ADN en situation biologique est complexe notam-ment en raison de la présence d’histones, protéines nucléaires, associées en quantité approximativement égales à l’ADN pour former la chromatine. Les histones possèdent de nombreux radicaux basiques arginine et lysine chargés positivement et dont la majorité se trouve sur les chaînes émergentes, l’ADN présente quant à lui des charges négatives sur ses groupements phosphates localisés tout au long de la double hélice. Dans cette étude, la complexité de la structure de la chromatine nucléaire est dans un premier temps mimée en solution aqueuse par la formation de complexes entre un ADN plasmidique sonde et les trois acides aminés basiques, Arg, His, Lys, qui, mis à part His, sont protonés au pH physiologique. Ces acides aminés libres en solution sont réputés être des capteurs efficaces de radicaux libres, notamment pour le radical hydroxyle, conférant ainsi un pouvoir protecteur vis-à-vis des effets indirects sur l’ADN en situation d’exposition aux rayonnements ionisants. A concentration fixée, les capacités de capture des acides aminés libres, σ, pour le radical hydroxyle sont typiquement les suivantes σHis ≈σArg > σLys (σLys ≈ 0,1 × σArg. Nous avons mesuré les taux de cassures simple brin par plasmide et par Gray (χ lors d’expositions de solutions aqueuses de complexes [acide aminé – ADN plasmidique] aux rayons X ultra-mous (1,5 keV. A concentrations égales, les trois acides aminés complexés et présents en large excès ne manifestent pas une capacité de protection de l’ADN proportionnelle à leur capacité de capture libre et en solution ; on trouve en effet des taux de cassures dans l’ordre suivant χHis > χArg > χLys (χLys ≈ 0,01 χArg. Après avoir détaillé le mode opératoire de ces mesures, nous analyserons sur des bases bibliographiques, les modes spécifiques d’interaction des

  13. Measurement of the Ec.m.=184keV Resonance Strength in the Al26g(p,γ)Si27 Reaction

    Science.gov (United States)

    Ruiz, C.; Parikh, A.; José, J.; Buchmann, L.; Caggiano, J. A.; Chen, A. A.; Clark, J. A.; Crawford, H.; Davids, B.; D'Auria, J. M.; Davis, C.; Deibel, C.; Erikson, L.; Fogarty, L.; Frekers, D.; Greife, U.; Hussein, A.; Hutcheon, D. A.; Huyse, M.; Jewett, C.; Laird, A. M.; Lewis, R.; Mumby-Croft, P.; Olin, A.; Ottewell, D. F.; Ouellet, C. V.; Parker, P.; Pearson, J.; Ruprecht, G.; Trinczek, M.; Vockenhuber, C.; Wrede, C.

    2006-06-01

    The strength of the Ec.m.=184keV resonance in the Al26g(p,γ)Si27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF’s ISAC facility. We measure a value of ωγ=35±7μeV and a resonance energy of Ec.m.=184±1keV, consistent with p-wave proton capture into the 7652(3) keV state in Si27, and discuss the implications of these values for Al26g nucleosynthesis in typical oxygen-neon white-dwarf novae.

  14. Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction.

    Science.gov (United States)

    Ruiz, C; Parikh, A; José, J; Buchmann, L; Caggiano, J A; Chen, A A; Clark, J A; Crawford, H; Davids, B; D'Auria, J M; Davis, C; Deibel, C; Erikson, L; Fogarty, L; Frekers, D; Greife, U; Hussein, A; Hutcheon, D A; Huyse, M; Jewett, C; Laird, A M; Lewis, R; Mumby-Croft, P; Olin, A; Ottewell, D F; Ouellet, C V; Parker, P; Pearson, J; Ruprecht, G; Trinczek, M; Vockenhuber, C; Wrede, C

    2006-06-30

    The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

  15. Minnesota Pheasant Range

    Data.gov (United States)

    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...

  16. Towards optimal range medians

    DEFF Research Database (Denmark)

    Brodal, Gerth Stølting; Gfeller, Beat; Jørgensen, Allan Grønlund

    2011-01-01

    that in the cell-probe model, any data structure which supports updates in O(logO(1)n) time must have Ω(log n/loglog n) query time. Our approach naturally generalizes to higher-dimensional range median problems, where element positions and query ranges are multidimensional - it reduces a range median query...... to a logarithmic number of range counting queries....

  17. Efficiency calibration of an extended-range Ge detector by a detailed Monte Carlo simulation

    Energy Technology Data Exchange (ETDEWEB)

    Peyres, V. [Metrologia de Radiaciones Ionizantes, CIEMAT, Avda. Complutense 22, Madrid 28040 (Spain)], E-mail: Virginia.peyres@ciemat.es; Garcia-Torano, E. [Metrologia de Radiaciones Ionizantes, CIEMAT, Avda. Complutense 22, Madrid 28040 (Spain)

    2007-09-21

    A Monte Carlo simulation has been employed for calibrating an extended-range Ge detector in an energy range from 14 to 1800 keV. A set of sources from monoenergetic and multi-gamma emitters point were measured at 15 cm from the detector window and provided 26 experimental values to which the results of the simulations are compared. Discrepancies between simulated and experimental values are within 1 standard deviation, and relative differences are, in most cases, below 1%.

  18. Tau ranging revisited

    Science.gov (United States)

    Tausworthe, R. C.

    1987-01-01

    It is shown that a ranging receiver with a sufficient and reasonable number of correlators is competitive with the current sequential component ranging system by some 1.5 to 2.5 dB. The optimum transmitter code, the optimum receiver, and a near-maximum-lilelihood range-estimation algorithm are presented.

  19. A space bourne crystal diffraction telescope for the energy range of nuclear transitions

    Energy Technology Data Exchange (ETDEWEB)

    von Ballmoos, P.; Naya, J.E.; Albernhe, F.; Vedrenne, G. [Centre d`Etude Spatial des Rayonnements, Toulouse (France); Smither, R.K.; Faiz, M.; Fernandez, P.; Graber, T. [Argonne National Lab., IL (United States)

    1995-10-01

    Recent experimental work of the Toulouse-Argonne collaboration has opened for perspective of a focusing gamma-ray telescope operating in the energy range of nuclear transitions, featuring unprecedented sensitivity, angular and energy resolution. The instrument consists of a tunable crystal diffraction lens situated on a stabilized spacecraft, focusing gamma-rays onto a small array of Germanium detectors perched on an extendible boom. While the weight of such an instrument is less than 500 kg, it features an angular resolution of 15 in., an energy resolution of 2 keV and a 3 {sigma} narrow line sensitivity of a few times 10{sup {minus}7} photons s{sup {minus}1} cm{sup {minus}2} (10{sup 6} sec observation). This instrumental concept permits observation of any identified source at any selected line-energy in a range of typically 200 keV to 1300 keV. The resulting ``sequential`` operation mode makes sites of explosive nucleosynthesis natural scientific objectives for such a telescope: the nuclear lines of extragalactic supernovae ({sup 56}Ni, {sup 44}Ti, {sup 60}Fe) and galactic novae (p{sup {minus}}p{sup +} line, {sup 7}Be) are accessible to observation, one at a time, due to the erratic appearance and the sequence of half-lifes of these events. Other scientific objectives, include the narrow 511 keV line from galactic broad class annihilators (such as 1E1740-29, nova musca) and possible redshifted annihilation lines from AGN`s.

  20. Validation of modelled imaging plates sensitivity to 1-100 keV x-rays and spatial resolution characterisation for diagnostics for the “PETawatt Aquitaine Laser”

    Energy Technology Data Exchange (ETDEWEB)

    Boutoux, G., E-mail: boutoux@celia.u-bordeaux1.fr; Batani, D.; Burgy, F.; Ducret, J.-E.; Forestier-Colleoni, P.; Hulin, S.; Rabhi, N. [Université de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Duval, A.; Lecherbourg, L.; Reverdin, C. [CEA DAM DIF, F-91297 Arpajon (France); Jakubowska, K. [Institute of Plasma Physics and Laser Microfusion, Hery Street 23, 01-497 Warsaw (Poland); Université de Bordeaux, CNRS, CEA, CELIA (Centre Lasers Intenses et Applications), UMR 5107, F-33405 Talence (France); Szabo, C. I. [Theiss Research, 7411 Eads Avenue, La Jolla, California 92037 (United States); Bastiani-Ceccotti, S. [LULI, Ecole Polytechnique, CNRS, CEA, UPMC, 91128 Palaiseau (France); Consoli, F.; Curcio, A.; De Angelis, R.; Ingenito, F. [ENEA for EUROfusion, Via E. Fermi 45, 00044 Frascati, Rome (Italy); Baggio, J.; Raffestin, D. [CEA DAM CESTA, BP 12, F-33405 Le Barp (France)

    2016-04-15

    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.

  1. QUIET-TIME SUPRATHERMAL (∼0.1–1.5 keV) ELECTRONS IN THE SOLAR WIND

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Jiawei; Wang, Linghua; Zong, Qiugang; He, Jiansen; Tu, Chuanyi [School of Earth and Space Science, Peking University, Beijing 100871 (China); Li, Gang [Department of Physics and CSPAR, University of Alabama in Huntsville, Alabama 35899 (United States); Salem, Chadi S.; Bale, Stuart D. [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States); Wimmer-Schweingruber, Robert F., E-mail: wanglhwang@gmail.com [Institute for Experimental and Applied Physics, University of Kiel, Leibnizstrasse 11, D-24118 Kiel (Germany)

    2016-03-20

    We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1–1.5 keV) electrons measured by the WIND 3DP instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. After separating (beaming) strahl electrons from (isotropic) halo electrons according to their different behaviors in the angular distribution, we fit the observed energy spectrum of both strahl and halo electrons at ∼0.1–1.5 keV to a Kappa distribution function with an index κ and effective temperature T{sub eff}. We also calculate the number density n and average energy E{sub avg} of strahl and halo electrons by integrating the electron measurements between ∼0.1 and 1.5 keV. We find a strong positive correlation between κ and T{sub eff} for both strahl and halo electrons, and a strong positive correlation between the strahl n and halo n, likely reflecting the nature of the generation of these suprathermal electrons. In both solar cycles, κ is larger at solar minimum than at solar maximum for both strahl and halo electrons. The halo κ is generally smaller than the strahl κ (except during the solar minimum of cycle 23). The strahl n is larger at solar maximum, but the halo n shows no difference between solar minimum and maximum. Both the strahl n and halo n have no clear association with the solar wind core population, but the density ratio between the strahl and halo roughly anti-correlates (correlates) with the solar wind density (velocity)

  2. Development of a stacked detector system for the x-ray range and its possible applications

    Science.gov (United States)

    Maier, Daniel; Limousin, Olivier; Meuris, Aline; Pürckhauer, Sabina; Santangelo, Andrea; Schanz, Thomas; Tenzer, Christoph

    2014-07-01

    We have constructed a stacked detector system operating in the X-ray range from 0.5 keV to 250 keV that consists of a Si-based 64×64 DePFET-Matrix in front of a CdTe hybrid detector called Caliste-64. The setup is operated under laboratory conditions that approximate the expected environment of a space-borne observatory. The DePFET detector is an active pixel matrix that provides high count-rate capabilities with a near Fanolimited spectral resolution at energies up to 15 keV. The Caliste-64 hard X-ray camera consists of a 1mm thick CdTe crystal combined with very compact integrated readout electronics, constituting a high performance spectro-imager with event-triggered time-tagging capability in the energy range between 2 keV and 200 keV. In this combined geometry the DePFET detector works as the Low Energy Detector (LED) while the Caliste-64 - as the High Energy Detector (HED) - detects predominantly the high energetic photons that have passed the LED. In addition to the individual optimization of both detectors, we use the setup to test and optimize the performance of the combined detector system. Side-effects like X-ray fluorescence photons, electrical crosstalk, and mutual heating have negative impacts on the data quality and will be investigated. Besides the primary application as a combined imaging detector system with high sensitivity across a broad energy range, additional applications become feasible. Via the analysis of coincident events in both detectors we can estimate the capabilities of the setup to be used as a Compton camera and as an X-ray polarimeter - both desirable functionalities for use in the lab as well as for future X-ray missions.

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

    OpenAIRE

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

    2007-01-01

    We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4x4 mm2, 1 mm thickness) produc...

  4. On the source of the 5-55 keV Heliosphere ENAs measured with Cassini/INCA

    Science.gov (United States)

    Dialynas, Konstantinos; Roelof, Edmond; Mitchell, Donald; Krimigis, Stamatios; Decker, Robert

    2016-07-01

    The Low Energy Charged Particle (LECP) in situ measurements from V1 and V2 have revealed a reservoir of ions and electrons that constitute the heliosheath (HS) after crossing the termination shock (TS) 35deg north and 32deg south of the ecliptic plane at 94 and 84 astronomical units (1 AU= 1.5 x10 ^{8} km), respectively. The outer Heliosphere boundary, the Heliopause (HP), has now been determined in the direction of V1 to be at ˜122 AU. The in situ measurements by each Voyager were placed in a global context by remote sensing images using ENA obtained with the Ion and Neutral Camera (INCA) onboard Cassini orbiting Saturn. The ENA images have revealed a 5.2-55 keV hydrogen (H) ENA region (Belt) that loops through the celestial sphere and contributes to balancing the pressure of the interstellar magnetic field (ISMF). Here we address one of the remaining and most important questions: Where do the 5-55 keV ENAs that INCA measures come from? We analyzed INCA all-sky maps from 2003 to 2015 and compare the solar cycle (SC) variation of the ENAs in both the nose (upstream) and anti-nose (downstream) directions with the intensities of > 30 keV ions (source of ENA through charge exchange-CE with H) measured in-situ by V1 and V2, in overlapping energy bands ˜30-55 keV. ENA intensities decrease during the declining phase of SC23 by ˜x3 from 2003 to 2011 but recover through 2014 (SC24); similarly, V1 and V2 ion intensities also decrease and then recover through 2014. The similarity of time profiles of remotely sensed ENA and locally measured ions are consistent with (a) ENA originating in the HS, and (b) the global HS responding promptly (within ˜1-1.5 years) to outward-propagating solar wind changes throughout the SC. Further, recovery of the Belt during SC24 precedes asymmetrically from south to north in the general direction of the nose. This may be related to the non-symmetric evolution of solar coronal holes during SC recovery.

  5. Three-body dynamics in single ionization of atomic hydrogen by 75 keV proton impact.

    Science.gov (United States)

    Laforge, A C; Egodapitiya, K N; Alexander, J S; Hasan, A; Ciappina, M F; Khakoo, M A; Schulz, M

    2009-07-31

    Doubly differential cross sections for single ionization of atomic hydrogen by 75 keV proton impact have been measured and calculated as a function of the projectile scattering angle and energy loss. This pure three-body collision system represents a fundamental test case for the study of the reaction dynamics in few-body systems. A comparison between theory and experiment reveals that three-body dynamics is important at all scattering angles and that an accurate description of the role of the projectile-target-nucleus interaction remains a major challenge to theory.

  6. GAMMA-RAY COMPTON SPECTROSCOPY OF TUNGSTEN USING 662 KeV GAMMA-RAY RADIATION А

    Directory of Open Access Journals (Sweden)

    Samir A. Hamouda

    2016-06-01

    Full Text Available Compton profile measurement of Tungsten polycrystalline sample has been performed with 662 KeV γ-radiation from a cesium-137 source scattered at 900. The Spectrometer calibration and data corrections for the high energy experiment are discussed. The data are compared with the augmented-plane-wave (APW band theoretical Compton profile of Tungsten. Theoretical predictions show the band theory overestimates the momentum density at low momenta and underestimates it at intermediate momenta. The discrepancies between experiment and theory were attributed to some non-local exchange-correlation effects and the spin-orbital interaction effect which were neglected in the theoretical calculation.

  7. The 3.55 keV X-ray Line Signal from Excited Dark Matter in Radiative Neutrino Model

    CERN Document Server

    Okada, Hiroshi

    2014-01-01

    We study an exciting dark matter in a radiative neutrino model to explain the X-ray line signal at $3.55$ keV recently reported by XMN-Newton X-ray observatory using data of various galaxy clusters and Andromeda galaxy, in which we show radiative neutrino masses mediated by our DM at ${\\cal O}$(10) GeV. Also we show that the required large cross section to explain the X-ray line can be obtained via the resonance of the pseudo-scalar.

  8. Time differential 57Fe Mössbauer spectrometer with unique 4π YAP:Ce 122.06 keV gamma-photon detector

    Science.gov (United States)

    Novak, Petr; Pechousek, Jiri; Prochazka, Vit; Navarik, Jakub; Kouril, Lukas; Kohout, Pavel; Vrba, Vlastimil; Machala, Libor

    2016-10-01

    This paper presents a conceptually new design of the 57Fe Time Differential Mössbauer Spectrometer (TDMS) with the gamma-photon detector optimized for registration of a radiation emitted in a maximum solid angle. A high detection efficiency of 80% in 4π region was achieved for 122.06 keV photons emitted from 57Co source. Detector parameters have been optimized for the use in the Time Differential Mössbauer Spectroscopy where the high time resolution in range of 176-200 ns is highly required. Technical concept of the TDMS is based on the virtual instrumentation technique and uses fast digital oscilloscope. Performance and detector utilization have been clarified by decreasing the Mössbauer spectral line-width of K2MgFe(CN)6 reference sample from 0.33 mm/s (integral mode) to 0.23 mm/s (time differential mode). This report also describes characterization and utilization of the detector together with additional electronic blocks and two-channel fast data-acquisition system construction.

  9. Ultrasoft 1.5 keV aluminum K X rays are efficient producers of complex chromosome exchange aberrations as revealed by fluorescence in situ hybridization.

    Science.gov (United States)

    Griffin, C S; Stevens, D L; Savage, J R

    1996-08-01

    The electron pairs generated by ultrasoft 1.5 keV aluminum K X-ray photons deposit their energy in tracks of length < 70 nm and provide an ideal tool for analyzing the spatial distribution of breaks and misrepair processes. We have undertaken the analysis of changes in chromosome structure produced by aluminum K X rays in untransformed HF12 human fibroblasts in G1 phase using fluorescence in situ hybridization (FISH). Multicolored chromosome-specific DNA probes for chromosomes 1 and 2 and an alpha-satellite pan-centromeric probe were used to examine in vitro radiation-induced chromosome-type exchange aberrations. After mean doses of 0.37-2.93 Gy the relative frequencies of complex exchanges, derived from three or more breaks in two or more chromosomes, ranged from 15-35%. For the classic break-age-and-rejoining theory to hold, very large interaction distances are needed to account for this high frequency of multibreak interactions, unless many sites pre-exist where several different chromosomes come very close together. Alternatively, damaged DNA may be able to interact with adjacent undamaged DNA, obviating the need for large rejoining distances.

  10. Dark Matter Inelastic Up-Scattering with the Interstellar Plasma: An Exciting New Source of X-Ray Lines, including at 3.5 keV

    CERN Document Server

    D'Eramo, Francesco; Profumo, Stefano; Stefaniak, Tim

    2016-01-01

    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 quasi-monochromatic 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 co...

  11. Dense ion clouds of 0.1 − 2 keV ions inside the CPS-region observed by Astrid-2

    Directory of Open Access Journals (Sweden)

    O. Norberg

    Full Text Available Data from the Astrid-2 satellite taken between April and July 1999 show several examples of dense ion clouds in the 0.1–2 keV energy range inside the inner mag-netosphere, both in the northern and southern hemispheres. These inner magnetospheric ion clouds are found predomi-nantly in the early morning sector, suggesting that they could have originated from substorm-related ion injections on the night side. However, their location and density show no cor-relation with Kp, and their energy-latitude dispersion is not easily reproduced by a simple particle drift model. There-fore, these ion clouds are not necessarily caused by substorm-related ion injections. Alternative explanations for the ion clouds are the direct solar wind injections and up-welling ions from the other hemisphere. These explanations do not, however, account for all of the observations.Key words. Magnetospheric physics (energetic particles, trapped; magnetospheric configuration and dynamics; storm and substorms

  12. Time differential {sup 57}Fe Mössbauer spectrometer with unique 4π YAP:Ce 122.06 keV gamma-photon detector

    Energy Technology Data Exchange (ETDEWEB)

    Novak, Petr [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77 146 Olomouc (Czech Republic); Pechousek, Jiri, E-mail: jiri.pechousek@upol.cz [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77 146 Olomouc (Czech Republic); Prochazka, Vit [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77 146 Olomouc (Czech Republic); Navarik, Jakub [Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 12, 77 146 Olomouc (Czech Republic); Kouril, Lukas; Kohout, Pavel; Vrba, Vlastimil [Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 1192/12, 77 146 Olomouc (Czech Republic); Machala, Libor [Regional Centre of Advanced Technologies and Materials, Department of Experimental Physics, Faculty of Science, Palacky University, 17. listopadu 12, 77 146 Olomouc (Czech Republic)

    2016-10-01

    This paper presents a conceptually new design of the {sup 57}Fe Time Differential Mössbauer Spectrometer (TDMS) with the gamma-photon detector optimized for registration of a radiation emitted in a maximum solid angle. A high detection efficiency of 80% in 4π region was achieved for 122.06 keV photons emitted from {sup 57}Co source. Detector parameters have been optimized for the use in the Time Differential Mössbauer Spectroscopy where the high time resolution in range of 176–200 ns is highly required. Technical concept of the TDMS is based on the virtual instrumentation technique and uses fast digital oscilloscope. Performance and detector utilization have been clarified by decreasing the Mössbauer spectral line-width of K{sub 2}MgFe(CN){sub 6} reference sample from 0.33 mm/s (integral mode) to 0.23 mm/s (time differential mode). This report also describes characterization and utilization of the detector together with additional electronic blocks and two-channel fast data-acquisition system construction.

  13. Extension of self-seeding to hard X-rays >10 keV as a way to increase user access at the European XFEL

    CERN Document Server

    Geloni, Gianluca; Saldin, Evgeni

    2011-01-01

    We propose to use the self-seeding scheme with single crystal monochromator at the European X-ray FEL to produce monochromatic, high-power radiation at 16 keV. Based on start to end simulations we show that the FEL power of the transform-limited pulses can reach about 100 GW by exploiting tapering in the tunable-gap baseline undulator. The combination of high photon energy, high peak power, and very narrow bandwidth opens a vast new range of applications, and includes the possibility to considerably increase the user capacity and fully exploit the high repetition rate of the European XFEL. In fact, dealing with monochromatic hard X-ray radiation one may use crystals as deflectors with minimum beam loss. To this end, a photon beam distribution system based on the use of crystals in the Bragg reflection geometry is proposed for future study and possible extension of the baseline facility. They can be repeated a number of times to form an almost complete (one meter scale) ring with an angle of 20 degrees between...

  14. Study and qualification of solid and gaseous captors designated to X imaging at around 60 keV; Etude et qualification de capteurs solide et gazeux en vue de leur utilisation en imagerie X autour de 60 keV

    Energy Technology Data Exchange (ETDEWEB)

    Ismaili, Y. [Caen Univ., 14 (France). Lab. de Physique Corpusculaire

    1996-09-01

    X ray detection techniques are used in numerous fields: industrial applications, security systems, scientific research and medicine. Among the medical applications, the dual energy detection of X-rays around 60 keV is used for bone densitometry. This thesis presents the design, realization and characterization of several kinds of detectors that could be suitable for X-ray imaging around 60 keV, bone densitometry being one the possible applications. The first part of this thesis is devoted to the realization of an original three-step gaseous detector coupled with a microchannel plate converter. The operating principle, the characteristics and the performance of such a bi-dimensional detector are discussed. Our study has allowed us to improve the efficiency by a factor of two, as compared to other systems based on the same principle. The obtained images have an excellent spatial resolution and can also be used to discriminate materials with different compositions. The work related to the study of a mono-dimensional detector constitutes the second part of the thesis. It is about the evaluation and optimization of a 8 element array made of Cd Te (Cadmium Telluride) which is a semi-conductor operating at room temperature. The tests carried-out with this detector show that it is a promising candidate for bone densitometry measurements. (author) 48 refs.

  15. Substring Range Reporting

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li

    2011-01-01

    We revisit various string indexing problems with range reporting features, namely, position-restricted substring searching, indexing substrings with gaps, and indexing substrings with intervals. We obtain the following main results. – We give efficient reductions for each of the above problems...... to a new problem, which we call substring range reporting. Hence, we unify the previous work by showing that we may restrict our attention to a single problem rather than studying each of the above problems individually. – We show how to solve substring range reporting with optimal query time and little...... range reporting are based on a novel combination of suffix trees and range reporting data structures. The reductions are simple and general and may apply to other combinations of string indexing with range reporting....

  16. Central Makran Range, Pakistan

    Science.gov (United States)

    1981-01-01

    A spectacular view of the Makran Range of Pakistan (27.0N, 65.5E) looking north with the Arabian Sea and the city of Karachi in the foreground. In the center, the Indian sub-continent moving slowly north into the Asian continent has caused the folded sedimentary Makran Range to bend from east-west to north-south as well as the uplift forming The Great Himalaya Range and the high Tibetan Plateau to the north.

  17. ISIS/EPI-Lo: A New Instrument for Measuring keV to MeV Ions and Electrons with Simultaneous Half-Sky Coverage on NASA's Solar Probe Plus Mission

    Science.gov (United States)

    Hill, M. E.; Mitchell, D. G.; McNutt, R. L., Jr.; Cooper, S.; Crew, A. B.; Dupont, A.; Hayes, J.; Hoffer, E.; Nelson, K.; Parker, C.; Schlemm, C., II; Seifert, H.; Stokes, M.; Angold, N. G.; McComas, D. J.; Weidner, S.; Wiedenbeck, M. E.

    2016-12-01

    The Solar Probe Plus (SPP) Mission's Integrated Science Investigation of the Sun (ISIS) is a suite of two energetic particle instruments, EPI-Lo and EPI-Hi, covering lower ( 10 keV-100 MeV) and higher ( 1-100 MeV/nuc) energies, respectively. The ISIS team will investigate the origins, acceleration, and transport of energetic particles in the corona and inner heliosphere during the planned 7-year, 24-orbit mission, with a perihelion initially of 0.16 AU (36 Solar radii; RS), the three final orbits reaching 0.044 AU (9.9 RS). EPI-Lo has a novel approach to obtaining large angular coverage, well-suited to 3-axis stabilized spacecraft such as SPP, by densely sampling its 2π steradian field of view with 80 apertures organized in eight matching, 10-aperture wedges. Each wedge relies primarily on time-of-flight (TOF) mass spectrometer techniques, employing thin secondary-electron-emitting foils, microchannel plates, and solid state detectors (SSDs), to measure ions from 50 keV - 15 MeV and electrons from 50-500 keV. Signal attenuation, absorbers, TOF-only measurements, and SSD-only techniques are used to extend this energy range higher and lower. In 2015 and 2016 we made measurements with engineering units and flight-spare EPI-Lo wedges at accelerators and with radioactive sources; in addition to presenting the instrument design, we will report the results from these tests to characterize the instrument's measurement performance.

  18. Baculovirus Host-Range

    Institute of Scientific and Technical Information of China (English)

    Suzanne M. Thiem; Xiao-Wen Cheng

    2009-01-01

    Baculoviruses are used as microbial insecticides, protein expression vectors, epitope display platforms, and most recently as vectors for gene therapy. Understanding the mechanisms that control baculovirus host-range and tissue tropisms are important for assessing their safety and for improving their properties for these biotechnology applications. In the past two decades some progress has been made and several baculovirus genes that influence host-range have been identified. Despite this progress, our understanding of the underlying mechanisms that restrict baculovirus host-range is still limited. Here we review what is currently known about baculovirus genes that influence virus host-range.

  19. Compact Antenna Range

    Data.gov (United States)

    Federal Laboratory Consortium — Facility consists of a folded compact antenna range including a computer controlled three axis position table, parabolic reflector and RF sources for the measurement...

  20. Laser Range Sensors

    Directory of Open Access Journals (Sweden)

    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.

  1. Dryden Aeronautical Test Range

    Data.gov (United States)

    Federal Laboratory Consortium — Recently redesignated to honor Dr. Hugh L. Dryden, NASA's Dryden Aeronautical Test Range (DATR) supports aerospace flight research and technology integration, space...

  2. Compact Antenna Range

    Data.gov (United States)

    Federal Laboratory Consortium — Facility consists of a folded compact antenna range including a computer controlled three axis position table, parabolic reflector and RF sources for the measurement...

  3. Sputtering of solid hydrogenic targets by keV hydrogen ions

    DEFF Research Database (Denmark)

    Stenum, B.; Schou, Jørgen; Ellegaard, O.;

    1991-01-01

    The first sputtering measurements of the most volatile solid hydrogenic targets are reported. Bombardment of these targets by hydrogen and deuterium ions leads to erosion predominantly via electronic transitions. The magnitude of the yield depends strongly on the particular isotope. No existing...... theory for this electronic sputtering can explain the large yields that range from about 100 D2/H for solid deuterium up to 800 H-2/H for solid hydrogen....

  4. Production of keV Sterile Neutrinos in Supernovae: New Constraints and Gamma Ray Observables

    CERN Document Server

    Argüelles, Carlos A; Kopp, Joachim

    2016-01-01

    We study the production of sterile neutrinos in supernovae, focusing in particular on the keV--MeV mass range, which is the most interesting range if sterile neutrinos are to account for the dark matter in the Universe. We argue that in this mass range, the production of sterile neutrinos can be strongly enhanced by a Mikheyev--Smirnov--Wolfenstein (MSW) resonance, so that a substantial flux is expected to emerge from a supernova, even if vacuum mixing angles between active and sterile neutrinos are tiny. Using energetics arguments, this yields limits on the sterile neutrino parameter space that reach down to mixing angles on the order of $\\sin^2 2\\theta \\lesssim 10^{-14}$ and are up to several orders of magnitude stronger than those from X-ray observations. We also compute the flux of $\\mathcal{O}(\\text{MeV})$ photons expected from the decay of sterile neutrinos produced in supernovae, but find that it is beyond current observational reach even for a nearby supernova.

  5. Understanding Bright 13 keV Kr K-shell X-ray Sources at the NIF

    Science.gov (United States)

    May, M. J.; Colvin, J. D.; Kemp, G. E.; Fournier, K. B.; Scott, H.; Patel, M.; Barrios, Widmann; Widmann, K.

    2015-11-01

    High x-ray conversion efficiency (CE) K-shell Kr sources are being investigated for High Energy Density experiments. These sources are 4.1 mm in diameter 4.4 mm tall hollow epoxy tubes having a 40 μm thick wall holding either 1.2 or 1.5 atm of Kr gas. The CE of K-shell Kr is dependent upon the peak electron temperature in the radiating plasma. In the NIF experiments, the available energy heats the source to Te = 6-7 keV, well below the temperature of Te ~25 keV needed to optimize the Kr CE. The CE is a steep function of the peak electron temperature. A spatially averaged electron temperature can be estimated from measured He(α) and Ly(α) line ratios. Some disagreement has been observed in the simulated and measured line ratios for some of these K-shell sources. Disagreements have been observed between the simulated and measured line ratios for some of these K-shell sources. To help understand this issue, Kr gas pipes have been shot with 3 ω light at ?750 kJ at ~210, ~140 TW and ~120 TW power levels with 3.7, 5.2 and 6.7 ns pulses, respectively. The power and pulse length scaling of the measured CE and K-shell line ratios and their comparison to simulations will be discussed. This work was performed under the auspic

  6. Testing the origin of ~3.55 keV line in individual galaxy clusters observed with XMM-Newton

    CERN Document Server

    Iakubovskyi, Dmytro; Foster, Adam R; Savchenko, Denys; Sadova, Valentyna

    2015-01-01

    If the unidentified emission line at ~3.55 keV previously found in spectra of nearby galaxies and galaxy clusters is due to radiatively decaying dark matter, one should detect the signal of comparable strength from many cosmic objects of different nature. By studying existing dark matter distributions in galaxy clusters we identified top-19 of them observed by XMM-Newton X-ray cosmic mission, and analyzed the data for the presence of the new line. In 8 of them, we identified > 2 sigma positive line-like residuals with average position 3.52 +/- 0.08 keV in the emitter's frame. Their observed properties are unlikely to be explained by statistical fluctuations or astrophysical emission lines; observed line position in M31 and Galactic Center makes an additional argument against general-type systematics. Being interpreted as decaying dark matter line, the new detections correspond to radiative decay lifetime tau_dm ~ (3.5-6) x 10^27 s consistent with previous detections.

  7. An Einstein survey of the 1 keV soft X-ray background in the Galactic plane

    Science.gov (United States)

    Stanford, John M.; Caillault, Jean-Pierre

    1994-01-01

    We have analyzed 56 Einstein Observatory Imaging Proportional Counter (IPC) observations within +/- 3 deg of the Galactic plane in order to determine the low-latitude soft X-ray background flux in the 0.56-1.73 keV band. Any detected X-ray point source which fell within our regions of study was removed from the image, enabling us to present maps of the background flux as a function of Galactic latitude along 18 meridians. These maps reveal considerable structure to the background in the Galactic plane on an angular scale of approximately 1 deg. Our results are compared with those of an earlier study of the 1 keV X-ray background along l = 25 deg by Kahn & Caillault. The double-peaked structure they found is not discernible in our results, possibly because of the presence of solar backscattered flux in their data. A model which takes into account contributions to the background by extragalactic and stellar sources, the distribution of both atomic and molecular absorbing material with the Galaxy, the energy dependence of the cross section for absorption of X-rays, and the energy dependence of the detector has been constructed and fitted to these new data to derive constraints on the scale height, temperature, and volume emissivity of the unaccounted-for X-ray-emitting material. The results of this model along l = 25 deg are roughly similar to those of the model of Kahn & Caillault along the same meridian.

  8. Measurement of the Erc .m .=259 keV resonance in the 14N(p ,γ )15O reaction

    Science.gov (United States)

    Daigle, S.; Kelly, K. J.; Champagne, A. E.; Buckner, M. Q.; Iliadis, C.; Howard, C.

    2016-08-01

    The 14N(p ,γ )15O reaction regulates the power generated by the CN cycle and thus impacts the structure and evolution of every star at some point in its life. The lowest positive-energy resonance in this reaction is located at Erc .m .=259 keV, too high in energy to strongly influence quiescent stellar burning. However, the strength of this resonance is used as a cross-section normalization for lower-energy measurements of this reaction. We report on new measurements of the energy, strength, and γ -ray branching ratios for the 259-keV resonance, using different detection and data-analysis schemes. We have also reevaluated previous results, where possible. Our new recommended strength of ω γ =12.6 (3 ) meV is in agreement with the previous value of 13.1(6) meV, but is more precise and thus provides a more reliable normalization for low-energy (p ,γ ) measurements.

  9. Ruling out the light weakly interacting massive particle explanation of the Galactic 511 keV line

    Science.gov (United States)

    Wilkinson, Ryan J.; Vincent, Aaron C.; BÅ`hm, Céline; McCabe, Christopher

    2016-11-01

    Over the past few decades, an anomalous 511 keV gamma-ray line has been observed from the center of the Milky Way. Dark matter (DM) in the form of light (≲10 MeV ) weakly interacting massive particles (WIMPs) annihilating into electron-positron pairs has been one of the leading hypotheses of the observed emission. Given the small required cross section, ⟨σ v ⟩˜1 0-30 cm3 s-1 , a further coupling to lighter particles is required to produce the correct relic density. Here, we derive constraints from the Planck satellite on light WIMPs that were in equilibrium with either the neutrino or electron sector in the early universe. For the neutrino sector, we obtain a lower bound on the WIMP mass of 4 MeV for a real scalar and 10 MeV for a Dirac fermion DM particle, at 95% C.L. For the electron sector, we find even stronger bounds of 7 and 11 MeV, respectively. Using these results, we show that, in the absence of additional ingredients such as dark radiation, the light thermally produced WIMP explanation of the 511 keV excess is strongly disfavored by the latest cosmological data. This suggests an unknown astrophysical or more exotic DM source of the signal.

  10. On the Origin of the 6.4 keV Line in the Galactic Center Region

    CERN Document Server

    Dogiel, V A; Kiselev, A M; Cheng, K -S

    2013-01-01

    We analyse the 6.4 keV iron line component produced in the Galactic Center (GC) region by cosmic rays in dense molecular clouds (MCs) and in the diffuse molecular gas. We showed that this component, in principle, can be seen in several years in the direction of the cloud Srg B2. If this emission is produced by low energy CRs which ionize the interstellar molecular gas the intensity of the line is quite small, < 1%. However, we cannot exclude that local sources of CRs or X-ray photons nearby the cloud may provide much higher intensity of the line from there. Production of the line emission from molecular clouds depends strongly on processes of CR penetration into them. We show that turbulent motions of neutral gas may generate strong magnetic fluctuations in the clouds which prevent free penetration of CRs into the clouds from outside. We provide a special analysis of the line production by high energy electrons. We concluded that these electrons hardly provide the diffuse 6.4 keV line emission from the GC ...

  11. Electron events from the scattering with solar neutrinos in the search of keV scale sterile neutrino dark matter

    Science.gov (United States)

    Liao, Wei; Wu, Xiao-Hong; Zhou, Hang

    2014-05-01

    In a previous work, we showed that it is possible to detect keV scale sterile neutrino dark matter νs in a β decay experiment using radioactive sources such as T3 or Ru106. The signals of this dark matter candidate are monoenergetic electrons produced in the neutrino capture process νs+ N'→N+e-. These electrons have energy greater than the maximum energy of the electrons produced in the associated decay process N'→N+e-+ν ¯e. Hence, signal electron events are well beyond the end point of the β decay spectrum and are not polluted by the β decay process. Another possible background, which is a potential threat to the detection of νs dark matter, is the electron event produced by the scattering of solar neutrinos with electrons in target matter. In this article, we study in detail this possible background and discuss its implications for the detection of keV scale sterile neutrino dark matter. In particular, bound state features of electrons in Ru atoms are considered with care in the scattering process when the kinetic energy of the final electron is the same order of magnitude of the binding energy.

  12. Strength of the $E_{\\text{cm}} = 1113$ keV resonance in $^{20}${Ne}$(p, \\gamma)^{21}${Na}

    CERN Document Server

    Christian, G; Akers, C; Connolly, D; Fallis, J; Ruiz, C

    2013-01-01

    The $^{20}$Ne$(p, \\gamma)^{21}$Na reaction is the starting point of the NeNa cycle, which is an important process for the production of intermediate mass elements. The $E_{\\text{cm}} = 1113$ keV resonance plays an important role in the determination of stellar rates for this reaction since it is used to normalize experimental direct capture yields at lower energies. The commonly accepted strength of this resonance, $\\omega \\gamma = 1.13 \\pm 0.07$ eV, has been misinterpreted as the strength in the center-of-mass frame when it is actually the strength in the laboratory frame. This has motivated a new measurement of the $E_{\\text{cm}} = 1113$ keV resonance strength in $^{20}$Ne$(p, \\gamma)^{21}$Na using the DRAGON recoil mass spectrometer. The DRAGON result, $0.972 \\pm 0.11$ eV, is in good agreement with the accepted value when both are calculated in the same frame of reference.

  13. ENHANCEMENT OF THE 6.4 keV LINE IN THE INNER GALACTIC RIDGE: PROTON-INDUCED FLUORESCENCE?

    Energy Technology Data Exchange (ETDEWEB)

    Nobukawa, K. K.; Nobukawa, M.; Tsuru, T. G.; Tanaka, T.; Koyama, K. [Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Uchiyama, H. [Faculty of Education, Shizuoka University, 836 Ohya, Suruga-ku, Shizuoka 422-8529 (Japan); Torii, K.; Fukui, Y. [Department of Physics, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8601 (Japan); Chernyshov, D. O.; Dogiel, V. A., E-mail: kumiko@cr.scphys.kyoto-u.ac.jp [P. N. Lebedev Institute, Leninskii pr, 53, Moscow 119991 (Russian Federation)

    2015-07-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A* because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with the molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with a large equivalent width of ∼1.3 keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudinal distribution of the excess emission disfavors the X-ray irradiation, either by Sagittarius A* or by nearby X-ray binaries. Then, the low-energy proton bombardment is the most probable origin, although the high-energy density ∼80 eV cm{sup −3} in 0.1–1000 MeV is required and there is no conventional proton source in the vicinity.

  14. Enhancement of the 6.4 keV line in the inner Galactic ridge: Proton-induced fluorescence?

    CERN Document Server

    Nobukawa, K K; Uchiyama, H; Tsuru, T G; Torii, K; Tanaka, T; Chernyshov, D O; Fukui, Y; Dogiel, V A; Koyama, K

    2015-01-01

    A common idea for the origin of the Galactic diffuse X-ray emission, particularly that of the iron lines from neutral and highly ionized atoms, is a superposition of many cataclysmic variables and coronally active binaries. In this scenario, the flux should symmetrically distribute between the east and west on the plane with respect to Sagittarius A$^*$ because the stellar mass distribution determined by infrared observations is nearly symmetric. This symmetry is confirmed for the highly ionized iron line as well as the continuum emission. However, a clear excess of the neutral iron line in the near east of the Galactic center compared to the near-west side is found. The flux distribution of the excess emission well correlates with molecular column density. The X-ray spectrum of the excess emission is described by a power-law continuum plus a 6.4 keV line with the large equivalent width of $\\sim1.3$ keV, which is hardly explained by the low-energy electron bombardment scenario. The longitudinal and latitudina...

  15. Search for 511 keV Emission in Satellite Galaxies of the Milky Way with INTEGRAL/SPI

    CERN Document Server

    Siegert, Thomas; Vincent, Aaron C; Guglielmetti, Fabrizia; Krause, Martin G H; Boehm, Celine

    2016-01-01

    The positron annihilation gamma-ray signal in the Milky Way (MW) shows a puzzling morphology: a very bright bulge and a very low surface-brightness disk. A coherent explanation of the positron origin, propagation through the Galaxy and subsequent annihilation in the interstellar medium has not yet been found. Tentative explanations involve positrons from radioactivity, X-ray binaries, and dark matter (DM). Dwarf satellite galaxies (DSGs) are believed to be DM-dominated and hence promising candidates in the search for 511 keV emission as a result of DM annihilation into electron-positron pairs. The goal of this study is to constrain possible 511 keV gamma-ray signals from 39 DSGs of the MW and to test the annihilating DM scenario. We use the spectrometer SPI on INTEGRAL to extract individual spectra for the studied objects. As the diffuse galactic emission dominates the signal, the large scale morphology of the MW has been modelled accordingly and was included in a maximum likelihood analysis. Alternatively, a...

  16. Sputtering of thin benzene and polystyrene overlayers by keV Ga and C{sub 60} bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Czerwinski, B. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, Cracow 30-059 (Poland); Delcorte, A. [PCPM, Universite Catholique de Louvain, Croix du Sud 1, B-1348 Louvain-la-Neuve (Belgium); Garrison, B.J. [104 Chemistry Building, Department of Chemistry, Penn State University, University Park, PA 16802 (United States); Samson, R. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, Cracow 30-059 (Poland); Winograd, N. [104 Chemistry Building, Department of Chemistry, Penn State University, University Park, PA 16802 (United States); Postawa, Z. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, Cracow 30-059 (Poland)]. E-mail: zp@castor.if.uj.edu.pl

    2006-07-30

    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{l_brace}1 1 1{r_brace} is irradiated by 15 keV Ga and C{sub 60} 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 C{sub 60}, 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 C{sub 60} 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 C{sub 60} projectiles.

  17. Sputtering of Langmuir-Blodgett multilayers by keV C{sub 60} projectiles as seen by computer simulations

    Energy Technology Data Exchange (ETDEWEB)

    Paruch, R.; Rzeznik, L.; Czerwinski, B. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland); Garrison, B.J.; Winograd, N. [Department of Chemistry, Pennsylvania State University, University Park, PA 16802 (United States); Postawa, Z. [Smoluchowski Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Krakow (Poland)], E-mail: zp@castor.if.uj.edu.pl

    2009-08-15

    Fundamental processes induced in a thick organic system composed of long, well-organized linear molecules by an impact of 5-20 keV C{sub 60} are investigated. The organic system is represented by Langmuir-Blodgett multilayers formed from bariated molecules of arachidic acid. The thickness of the system varies between 2 and 16 nm. Coarse-grained molecular dynamics computer simulations are applied to investigate the energy transfer pathways and sputtering yields as a function of the kinetic energy of the projectile and the thickness of the organic overlayer. The results indicate that an impact of keV C{sub 60} projectiles leads to significant ejection of organic material. The efficiency of desorption increases with the kinetic energy of the projectile for a given layer thickness. For a constant primary kinetic energy, the sputtering yield goes through a maximum and finally saturates as the LB layer becomes thicker. Such behaviour is caused by a competition between signal enhancement due to increasing number of organic molecules and signal decrease due to lowering of the amount of the primary energy being backreflected into the organic overlayer by the receding organic/metal interface as the layer is getting thicker. When the sample thickness becomes much larger than the penetration depth of the projectile, the sputtering yield is independent of thickness. The deposited energy is channelled by an open and ordered molecular structure, which leads to abnormally long projectile penetration and ion-induced damage.

  18. STUDY OF THE NUCLEAR PHENOMENA IN THE LOW ENERGY (60--360 keV) PROTON BEAM IMPLANTATION ON METALS

    Institute of Scientific and Technical Information of China (English)

    Wang Tie-shan; Zhu Yong-tai; Wang Zhi-guo; Li Song-lin; Wang Shu-jin; Jin Gen-ming

    2000-01-01

    A series of studies on the nuclear interaction and its effects in solidsduring proton implantation were performed in the energy region between60 and 360keV. Some charged particle products were observed in theimplantation experiments on metal samples such as deuterated titanium,titanium alloy, titanium foil on molybdenum substrate, molybdenum andstainless steel, etc.. The energies of the charged particle products areabout 3.9, 5.6 and 8.4MeV, respectively. These particles were identifiedas alpha particles with both detector telescope and absorptionmeasurements. These three kinds of alpha products were found fromdifferent proton sub-barrier reactions. The exciting curve of thisreaction increases exponentially with the growth of proton energy in theenergy region from 90 to 330keV. The radiation damages induced by thenuclear products in the sample have been studied with scanning electronmicroscopy technique. The possible surface damages induced by them wereobserved evidently. The origin of the nuclear reactions and their effecton implantation are discussed.

  19. L X-ray fluorescence cross sections experimentally determined for elements with 45keV

    Energy Technology Data Exchange (ETDEWEB)

    Bonzi, Edgardo V., E-mail: bonzie@famaf.unc.edu.ar [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria-5010, Cordoba (Argentina); Badiger, Nagappa M. [Departments of Physics, Karnatak University, Dharwad 580 003, Karnataka (India); Grad, Gabriela B. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria-5010, Cordoba (Argentina); Barrea, Raul A. [The Biophysics Collaborative Access Team (BioCAT), Dept of Biological Chemical, and Physical Sciences, Illinois Institute of Technology, Chicago, IL 60616 (United States); Figueroa, Rodolo G. [Departamento de Cs. Fisicas, Universidad de La Frontera, Temuco (Chile)

    2012-04-15

    Experimental determination of L fluorescence cross-sections for elements with 45keV using Synchrotron radiation. This work is part of an investigation we did at low energies in the same group of elements. The individual L X-ray photons, Ll, L{alpha}, L{beta}{sub I}, L{beta}{sub II}, L{gamma}{sub {Iota}} and L{gamma}{sub {Iota}{Iota}} produced in the target were measured using a Si(Li) detector. The experimental set-up provided a low background by using linearly polarized monoenergetic photon beam, improving the signal-to-noise ratio. The experimental cross sections obtained in this work were compared with data calculated using coefficients from , , and Scofield and Puri et al. (1993, 1995) - Highlights: Black-Right-Pointing-Pointer Experimental data of L fluorescence cross-sections with 45keV by Synchrotron radiation. Black-Right-Pointing-Pointer The cross sections Ll, L{alpha}, L{beta}{sub I}, L{beta}{sub II}, L{gamma}{sub {Iota}} and L{gamma}{sub {Iota}{Iota}} obtained, were compared with calculated data. Black-Right-Pointing-Pointer The Hypermet function was used to fit the data, because it considers a tail on the left side of the peak. Black-Right-Pointing-Pointer The tail is relevant when a small peak has another one on the right side with a big area.

  20. Relic gravity waves and 7 keV dark matter from a GeV scale inflaton

    Directory of Open Access Journals (Sweden)

    F.L. Bezrukov

    2014-09-01

    Full Text Available We study the mechanism of generation of 7 keV sterile neutrino Dark Matter (DM in the model with light inflaton χ, which serves as a messenger of scale invariance breaking. In this model the inflaton, in addition to providing reheating to the Standard Model (SM particles, decays directly into sterile neutrinos. The latter are responsible for the active neutrino oscillations via seesaw type I mechanism. While the two sterile neutrinos may also produce the lepton asymmetry in the primordial plasma and hence explain the baryon asymmetry of the Universe, the third one being the lightest may be of 7 keV and serve as DM. For this mechanism to work, the mass of the inflaton is bound to be light (0.1–1 GeV and uniquely determines its properties, which allows to test the model. For particle physics experiments these are: inflaton lifetime (10−5–10−12 s, branching ratio of B-meson to kaon and inflaton (10−6–10−4 and inflaton branching ratios into light SM particles like it would be for the SM Higgs boson of the same mass. For cosmological experiments these are: spectral index of scalar perturbations (ns≃0.957–0.967, and amount of tensor perturbations produced at inflation (tensor-to-scalar ratio r≃0.15–0.005.

  1. Electric Fields Associated with Deep Injections of 10s to 100s keV Electrons in the Inner Magnetosphere

    Science.gov (United States)

    Califf, S.; Li, X.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

    2015-12-01

    Recent observations by HOPE and MagEIS onboard the Van Allen Probes show frequent penetration of 10s to 100s keV electrons through the slot region and into the inner belt, resulting in an abundant electron population below L=3. The conventional picture is that the source populations of these 10s to 100s keV electrons originate in the plasma sheet and are injected (along with plasma sheet ions) into the inner magnetosphere either through enhancements in the large-scale convection electric field and/or through earthward propagating dipolarization fronts associated with substorms. In such cases the inward radial limit of the injections should coincide with the plasmapause. However, these electron injections often extend inside the plasmasphere, are observed far earthward of the typically accepted "flow-braking" region for dipolarization fronts, and occur at much lower L shells than injections of ions with similar energies. We investigate the electric fields associated with these deep electron injections using data from the Van Allen Probes and THEMIS in order to shed light on the underlying mechanisms that allow them to penetrate so far into the inner magnetosphere.

  2. Constraints on dark matter and the shape of the Milky Way dark halo from the 511 keV line

    CERN Document Server

    Ascasibar, Y; Knödlseder, J; Jean, P

    2006-01-01

    About one year ago, it was speculated that decaying or annihilating Light Dark Matter (LDM) particles could explain the flux and extension of the 511 keV line emission in the galactic centre. Here we present a thorough comparison between theoretical expectations of the galactic positron distribution within the LDM scenario and observational data from INTEGRAL/SPI. Unlike previous analyses, there is now enough statistical evidence to put tight constraints on the shape of the dark matter halo of our galaxy, if the galactic positrons originate from dark matter. For annihilating candidates, the best fit to the observed 511 keV emission is provided by a radial density profile with inner logarithmic slope gamma=1.03+-0.04. In contrast, decaying dark matter requires a much steeper density profile, gamma>1.5, rather disfavoured by both observations and numerical simulations. Within the annihilating LDM scenario, a velocity-independent cross-section would be consistent with the observational data while a cross-section...

  3. On Range of Skill

    DEFF Research Database (Denmark)

    Hansen, Thomas Dueholm; Miltersen, Peter Bro; Sørensen, Troels Bjerre

    2008-01-01

    size (and doubly exponential in its depth). We also provide techniques that yield concrete bounds for unbalanced game trees and apply these to estimate the Range of Skill of Tic-Tac-Toe and Heads-Up Limit Texas Hold'em Poker. In particular, we show that the Range of Skill of Tic-Tac-Toe is more than...

  4. Substring Range Reporting

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li

    2011-01-01

    to a new problem, which we call substring range reporting. Hence, we unify the previous work by showing that we may restrict our attention to a single problem rather than studying each of the above problems individually. – We show how to solve substring range reporting with optimal query time and little...

  5. Range Selection and Median

    DEFF Research Database (Denmark)

    Jørgensen, Allan Grønlund; Larsen, Kasper Green

    2011-01-01

    Range selection is the problem of preprocessing an input array A of n unique integers, such that given a query (i; j; k), one can report the k'th smallest integer in the subarray A[i];A[i+1]; : : : ;A[j]. In this paper we consider static data structures in the word-RAM for range selection and sev...

  6. Home range and travels

    Science.gov (United States)

    Stickel, L.F.; King, John A.

    1968-01-01

    The concept of home range was expressed by Seton (1909) in the term 'home region,' which Burr (1940, 1943) clarified with a definition of home range and exemplified in a definitive study of Peromyscus in the field. Burt pointed out the ever-changing characteristics of home-range area and the consequent absence of boundaries in the usual sense--a finding verified by investigators thereafter. In the studies summarized in this paper, sizes of home ranges of Peromyscus varied within two magnitudes, approximately from 0.1 acre to ten acres, in 34 studies conducted in a variety of habitats from the seaside dunes of Florida to the Alaskan forests. Variation in sizes of home ranges was correlated with both environmental and physiological factors; with habitat it was conspicuous, both in the same and different regions. Food supply also was related to size of home range, both seasonally and in relation to habitat. Home ranges generally were smallest in winter and largest in spring, at the onset of the breeding season. Activity and size also were affected by changes in weather. Activity was least when temperatures were low and nights were bright. Effects of rainfall were variable. Sizes varied according to sex and age; young mice remained in the parents' range until they approached maturity, when they began to travel more widely. Adult males commonly had larger home ranges than females, although there were a number of exceptions. An inverse relationship between population density and size of home range was shown in several studies and probably is the usual relationship. A basic need for activity and exploration also appeared to influence size of home range. Behavior within the home range was discussed in terms of travel patterns, travels in relation to home sites and refuges, territory, and stability of size of home range. Travels within the home range consisted of repeated use of well-worn trails to sites of food, shelter, and refuge, plus more random exploratory travels

  7. Electron beam generation in the fore-vacuum pressure range

    CERN Document Server

    Burachevskij, Y A; Kuzemchenko, M N; Mytnikov, A V; Oks, E M

    2001-01-01

    One presents the results of investigations to generate electron beams within 0.01-0.1 Torr gas pressure range. To generate a beam one used a plasma source based on a hollow cathode discharge in combination with a plane accelerating gap. Peculiar features of electron emission and acceleration within the mentioned pressure range are associated with high probability of gas ionization in an accelerating gap and with generation of ion flow meeting electron beam. It results in reduction of discharge combustion intensification, as well as, in plasma concentration range. The developed design of an electron source enables to generate cylindrical beams with up to 1 A current and with up to 10 keV energy

  8. Atlantic Test Range (ATR)

    Data.gov (United States)

    Federal Laboratory Consortium — ATR controls fully-instrumented and integrated test ranges that provide full-service support for cradle-to-grave testing. Airspace and surface target areas are used...

  9. Light Detection And Ranging

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — LiDAR (Light Detection and Ranging) discrete-return point cloud data are available in the American Society for Photogrammetry and Remote Sensing (ASPRS) LAS format....

  10. Range_Extent_15

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The GIS layer "Range_extent_15" is a simple polyline representing the geographic distribution of the southern sea otter (Enhydra lutris nereis) in mainland...

  11. On Range of Skill

    DEFF Research Database (Denmark)

    Hansen, Thomas Dueholm; Miltersen, Peter Bro; Sørensen, Troels Bjerre

    2008-01-01

    is a small number, but only gave heuristic arguments for this. In this paper, we provide the first methods for rigorously estimating the Range of Skill of a given game. We provide some general, asymptotic bounds that imply that the Range of Skill of a perfectly balanced game tree is almost exponential in its...... size (and doubly exponential in its depth). We also provide techniques that yield concrete bounds for unbalanced game trees and apply these to estimate the Range of Skill of Tic-Tac-Toe and Heads-Up Limit Texas Hold'em Poker. In particular, we show that the Range of Skill of Tic-Tac-Toe is more than...

  12. Correlation radio range finder

    Directory of Open Access Journals (Sweden)

    A. Sorochan

    2012-10-01

    Full Text Available In work widely known methods of range measuring are short characterized. The basic attention is given features of signal processing in a correlation method of range measuring. The signal with angular modulation with one-voice-frequency fluctuation is used as a probing signal. The absence of Doppler effect on the formation of the correlation integral, the frequency instability of the transmitter, the phase change on reflection from the target is presented. It is noticed that the result of signal processing in the range measuring instrument is reduced to formation on an exit one-voice-frequency harmonious fluctuation equal to modulating frequency that provides high characteristics of a radio range finder.

  13. Antenna Pattern Range (APR)

    Data.gov (United States)

    Federal Laboratory Consortium — TheAntenna Pattern Range (APR)features a non-metallic arch with a trolley to move the transmit antenna from the horizon to zenith. At the center of the ground plane,...

  14. Light Detection And Ranging

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — LiDAR (Light Detection and Ranging) discrete-return point cloud data are available in the American Society for Photogrammetry and Remote Sensing (ASPRS) LAS format....

  15. Substring Range Reporting

    OpenAIRE

    Bille, Philip; Gørtz, Inge Li

    2011-01-01

    We revisit various string indexing problems with range reporting features, namely, position-restricted substring searching, indexing substrings with gaps, and indexing substrings with intervals. We obtain the following main results. {itemize} We give efficient reductions for each of the above problems to a new problem, which we call \\emph{substring range reporting}. Hence, we unify the previous work by showing that we may restrict our attention to a single problem rather than studying each of...

  16. Substring Range Reporting

    OpenAIRE

    Bille, Philip; Gørtz, Inge Li

    2011-01-01

    We revisit various string indexing problems with range reporting features, namely, position-restricted substring searching, indexing substrings with gaps, and indexing substrings with intervals. We obtain the following main results. {itemize} We give efficient reductions for each of the above problems to a new problem, which we call \\emph{substring range reporting}. Hence, we unify the previous work by showing that we may restrict our attention to a single problem rather than studying each of...

  17. Differential scattering cross-sections, inelastic energy losses and ion fractions in backscattering of keV He sup + ions from monolayer metal adsorbates on solid surfaces measured by means of CAICISS

    CERN Document Server

    Kishi, N

    2002-01-01

    Energy spectra of He atoms and He sup + ions backscattered at an angle of approx 180 deg. by monolayer metal adsorbates (Ag, Sn, Sb, Pb and Bi) on the Si(1 1 1)-sq root 3x sq root 3 surfaces and monolayer Si atoms on the graphite surface have been measured by means of the coaxial impact collision ion scattering spectroscopy technique combined with low energy electron diffraction, Auger electron spectroscopy and Rutherford backscattering spectrometry techniques in the energy range from 0.5 to 3.0 keV. It is found from their data analysis that the ratios of the experimental scattering cross-section to the magic formula of the Thomas-Fermi cross-section for different adsorbates deviate from unity: for instance 1.2 for Si, 0.8 for Ag, 1.5 for Sn, 1.2 for Sb, 1.2 for Pb and 1.6 for Bi. It is also found that the average inelastic energy loss for Si increases monotonically with increasing the incident energy, while those for the other adsorbates increase stepwisely at around 1.0 keV and thereafter gradually. Moreove...

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

    Science.gov (United States)

    Singh, Amrit; Dhaliwal, A. S.

    2016-02-01

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

  19. Reducing the effects of metal artefact using high keV monoenergetic reconstruction of dual energy CT (DECT) in hip replacements

    Energy Technology Data Exchange (ETDEWEB)

    Lewis, Mark [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Norwich Radiology Academy, Norwich (United Kingdom); Reid, Karen [Norfolk and Norwich University Hospital, Norwich (United Kingdom); Toms, Andoni P. [Norfolk and Norwich University Hospital and University of East Anglia, Norwich (United Kingdom)

    2013-02-15

    The aim of this study was to determine whether high keV monoenergetic reconstruction of dual energy computed tomography (DECT) could be used to overcome the effects of beam hardening artefact that arise from preferential deflection of low energy photons. Two phantoms were used: a Charnley total hip replacement set in gelatine and a Catphan 500. DECT datasets were acquired at 100, 200 and 400 mA (Siemens Definition Flash, 100 and 140 kVp) and reconstructed using a standard combined algorithm (1:1) and then as monoenergetic reconstructions at 10 keV intervals from 40 to 190 keV. Semi-automated segmentation with threshold inpainting was used to obtain the attenuation values and standard deviation (SD) of the streak artefact. High contrast line pair resolution and background noise were assessed using the Catphan 500. Streak artefact is progressively reduced with increasing keV monoenergetic reconstructions. Reconstruction of a 400 mA acquisition at 150 keV results in reduction in the volume of streak artefact from 65 cm{sup 3} to 17 cm{sup 3} (74 %). There was a decrease in the contrast to noise ratio (CNR) at higher tube voltages, with the peak CNR seen at 70-80 keV. High contrast spatial resolution was maintained at high keV values. Monoenergetic reconstruction of dual energy CT at increasing theoretical kilovoltages reduces the streak artefact produced by beam hardening from orthopaedic prostheses, accompanied by a modest increase in heterogeneity of background image attenuation, and decrease in contrast to noise ratio, but no deterioration in high contrast line pair resolution. (orig.)

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

    Science.gov (United States)

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

    2015-04-01

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

  1. Range Information Propagation Transform

    Institute of Scientific and Technical Information of China (English)

    陈向荣; 朱志刚; 等

    1998-01-01

    A novel method of model-based object recognition is presented in this paper.Its novelty stems from the fact that the gray level image captured by a camera is merged with sparse range information in an active manner.By using a projective transform, which is determined by the sparse range data,festures(e.g.edge points)related to a single planar surface patch of figure in the scene can be assignew with their corresponding range values respectively.As a result,the shape of the very planar patch or figure can be recovered and various kinds of description in the Euclidean space can be calculated.Based on these descriptions values,the hypothesis about the identification of the object and its pose in space can be obtained with a high probability of success,and a high efficiency of hypothesis-verification process can be expected.Another advantage of this method is that the edge detection process can be navigated to the proper location hinted by the sparse range image.In consequence edge features can be extracted even in the regions with low contrast.In this paper the principle of range information propagation transform(RIPT)is explained,and some implementation issues,such as the algorithms using calibrated or uncalibrated gray level image for object recognition,are discussed.The preliminary experimental results are presented to indicate the effectiveness and efficiency of the proposed method.

  2. Range Selection and Median

    DEFF Research Database (Denmark)

    Jørgensen, Allan Grønlund; Larsen, Kasper Green

    2011-01-01

    and several natural special cases thereof. The rst special case is known as range median, which arises when k is xed to b(j 􀀀 i + 1)=2c. The second case, denoted prex selection, arises when i is xed to 0. Finally, we also consider the bounded rank prex selection problem and the xed rank range......Range selection is the problem of preprocessing an input array A of n unique integers, such that given a query (i; j; k), one can report the k'th smallest integer in the subarray A[i];A[i+1]; : : : ;A[j]. In this paper we consider static data structures in the word-RAM for range selection...... selection problem. In the former, data structures must support prex selection queries under the assumption that k for some value n given at construction time, while in the latter, data structures must support range selection queries where k is xed beforehand for all queries. We prove cell probe lower bounds...

  3. The half-life of the 1437 keV 11/2 sup - state in sup 97 Mo

    Energy Technology Data Exchange (ETDEWEB)

    Kostova, L.G.; Andrejtscheff, W.; Kostov, L.K. (Bylgarska Akademiya na Naukite, Sofia (Bulgaria). Inst. za Yadrena Izsledvaniya i Yadrena Energetika); Funke, L.; Will, E. (Zentralinstitut fuer Kernforschung, Rossendorf (Germany)); Vdovin, A.I. (Joint Inst. for Nuclear Research, Dubna (Russia))

    1992-05-01

    Using the ({alpha}, n) reaction, the half-life of the first 11/2{sup -} level in {sup 97}Mo has been determined as T{sub 1/2}(1437.0 keV)=2.5{+-}0.3 ns by means of the pulsed beam method. The experimentally obtained B(M2) value between the h{sub 11/2} and g{sub 7/2} configurations in {sup 97}Mo has been satisfactorily described within the quasiparticle-phonon model using g{sub s}{sup eff}=0.6 g{sub s}{sup free} c{sub s}. Similar calculations and comparisons with experimental data have been performed also for {sup 95,99}Mo as well as for {sup 99}Ru and {sup 101}Pd. (orig.).

  4. Experimental observations of Z-dependence of saturation thickness of 662 keV gamma rays in metals and glasses

    Science.gov (United States)

    Ravindraswami, K.; Kiran, K. U.; Eshwarappa, K. M.; Somashekarappa, H. M.

    2013-11-01

    In this paper the energy, intensity and angular distributions of multiple scattering of 662 keV gamma photons, emerging from targets of aluminium, copper, iron and glass samples are studied as a function of target thickness. An intense collimated beam obtained from a 137Cs source of 5.8 mCi is allowed to impinge on samples of varying thickness. The scattered photons are detected by a properly shielded 76 mm × 76 mm NaI (Tl) scintillation detector. In Compton scattering experiments, it is observed that the number of multiple backscattered photons increase with an increase in target thickness and become almost constant for particular target thickness called saturation thickness. The saturation thickness decreases with increasing atomic number. The multiple scattering, an interfering background noise in Compton profile, has been successfully used to assign effective atomic number (Z eff ) to composite materials. The experimental results are compared with the Monte Carlo calculations using Monte Carlo nuclear particle code.

  5. Medipix3 Demonstration and understanding of near ideal detector performance for 60 & 80 keV electrons

    CERN Document Server

    Mir, J A; MacInnes, R; Gough, C; Plackett, R; Shipsey, I; Sawada, H; MacLaren, I; Ballabriga, R; Maneuski, D; O'Shea, V; McGrouther, D; Kirkland, A I

    2016-01-01

    In our article we report first quantitative measurements of imaging performance for the current generation of hybrid pixel detector, Medipix3, as direct electron detector. Utilising beam energies of 60 & 80 keV, measurements of modulation transfer function (MTF) and detective quantum efficiency (DQE) have revealed that, in single pixel mode (SPM), energy threshold values can be chosen to maximize either the MTF or DQE, obtaining values near to, or even exceeding, those for an ideal detector. We have demonstrated that the Medipix3 charge summing mode (CSM) can deliver simultaneous, near ideal values of both MTF and DQE. To understand direct detection performance further we have characterized the detector response to single electron events, building an empirical model which can predict detector MTF and DQE performance based on energy threshold. Exemplifying our findings we demonstrate the Medipix3 imaging performance, recording a fully exposed electron diffraction pattern at 24-bit depth and images in SPM a...

  6. Classical physics impossibility of magnetic fusion reactor with neutral beam injection at thermonuclear energies below 200 KeV

    Science.gov (United States)

    Maglich, Bogdan; Hester, Timothy; Vaucher, Alexander

    2016-10-01

    Lawson criterion was specifically derived for inertial fusion and DT gas of stable lifetime without ions and magnetic fields. It was revised with realistic parametrers. To account for the losses of unstable ions against neutralization with lifetime τ, n (t) = nτ [ 1 - exp (- t / - tτ τ) ] -> nτ for τ CT resonance regime below critical energy To, τ 10-5 , and Lawson requirement ntL 1021 i.e. not realistic. Luminosity (reaction rate for σ = 1) is that of two unstable particles each with lifetime τ: L =n2(t)v12 =n2t2v12 . In subcritical regime, L =10-10n2 forn =1014cm-3 , v 109 cms-1 = L =1027 . Which is negligible and implies a negative power flow reactor. But above T0 , atTD = 725 KeV , τ = 20 s was observed implying L =1039 i.e. massive fusion energy production.

  7. Implantation of anatase thin film with 100 keV {sup 56}Fe ions: Damage formation and magnetic behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, J. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden)], E-mail: Jens.Jensen@telia.com; Sanz, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, ES-28049 Madrid (Spain); Martin, D. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Surpi, A. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Department of Biology and Chemical Engineering, Maelardalens Hoegskola, SE-632 20 Eskilstuna (Sweden); Kubart, T. [Department of Engineering Sciences, Uppsala Universitet, P.O. Box 534, SE-751 21, Uppsala (Sweden); Vazquez, M. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, ES-28049 Madrid (Spain); Hernandez-Velez, M. [Applied Physics Department, Universidad Autonoma de Madrid, ES-28049 Madrid (Spain)

    2009-08-15

    We have investigated the damage morphology and magnetic properties of titanium dioxide thin films following implantation with Fe ions. The titanium dioxide films, having a polycrystalline anatase structure, were implanted with 100 keV {sup 56}Fe{sup +} ions to a total fluence of 1.3 x 10{sup 16} ions/cm{sup 2}. The ion bombardment leads to an amorphized surface with no indication of the presence of secondary phases or Fe clusters. The ion-beam induced damage manifested itself by a marked change in surface morphology and film thickness. A room temperature ferromagnetic behaviour was observed by SQUID in the implanted sample. It is believed that the ion-beam induced damage and defects in the polycrystalline anatase film were partly responsible for the observed magnetic response.

  8. Differential cross sections for the single ionization of H2 by 75 keV proton impact

    Science.gov (United States)

    Igarashi, A.; Gulyás, L.

    2017-02-01

    We have calculated the double and triple differential cross sections for electron ejection with energy of 14.6 eV in single ionization of H2 by 75 keV proton impact. A molecular version of the continuum distorted wave-eikonal initial state approach is applied, where the interaction between the projectile and the residual molecular ion is considered more properly than in previous applications of the method. For triple differential cross sections, the present results are in better agreement with the experimental data than those of other descriptions when large momentum transfer values are considered. For double differential cross sections the experimental data are reproduced quite well for both coherent and incoherent proton beams.

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

    Science.gov (United States)

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

    2015-12-01

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

  10. X-ray Filament with a Strong 6.7 keV Line in the Galactic Center Region

    CERN Document Server

    Yamauchi, Shigeo; Nakashima, Shinya; Nobukawa, Masayoshi; Tsuru, Takeshi Go; Koyama, Katsuji

    2014-01-01

    An elongated X-ray source with a strong K-shell line from He-like iron (Fe XXVI) is found at (RA, Dec)_{J2000.0}=(17h44m00s.0, -29D13'40''.9) in the Galactic center region. The position coincides with the X-ray thread, G359.55+0.16, which is aligned with the radio non-thermal filament. The X-ray spectrum is well fitted with an absorbed thin thermal plasma (apec) model. The best-fit temperature, metal abundance, and column density are 4.1^{+2.7}_{-1.8} keV, 0.58^{+0.41}_{-0.32} solar, and 6.1^{+2.5}_{-1.3}x10^{22} cm^{-2}, respectively. These values are similar to those of the largely extended Galactic center X-ray emission.

  11. Surface wet-ability modification of thin PECVD silicon nitride layers by 40 keV argon ion treatments

    Science.gov (United States)

    Caridi, F.; Picciotto, A.; Vanzetti, L.; Iacob, E.; Scolaro, C.

    2015-10-01

    Measurements of wet-ability of liquid drops have been performed on a 30 nm silicon nitride (Si3N4) film deposited by a PECVD reactor on a silicon wafer and implanted by 40 keV argon ions at different doses. Surface treatments by using Ar ion beams have been employed to modify the wet-ability. The chemical composition of the first Si3N4 monolayer was investigated by means of X-ray Photoelectron Spectroscopy (XPS). The surface morphology was tested by Atomic Force Microscopy (AFM). Results put in evidence the best implantation conditions for silicon nitride to increase or to reduce the wet-ability of the biological liquid. This permits to improve the biocompatibility and functionality of Si3N4. In particular experimental results show that argon ion bombardment increases the contact angle, enhances the oxygen content and increases the surface roughness.

  12. Guided transmission of 3 keV Ne sup 7 sup + ions through nanocapillaries etched in a PET polymer

    CERN Document Server

    Stolterfoht, N; Hellhammer, R; Pesic, Z D; Fink, D; Petrov, A; Sulik, B

    2003-01-01

    We measured the transmission of 3 keV Ne sup 7 sup + ions through capillaries of 100 nm diameter and 10 mu m length produced by etching ion tracks in a polyethylene terephthalate polymer foil. The foils were tilted up to +-25 deg. for which the incident ions are forced to interact with the capillary surface. The majority of Ne sup 7 sup + ions were found to survive the transmission in their initial charge state. For tilted foils the angular distributions of the transmitted particles indicate propagation of the Ne sup 7 sup + ions parallel to the capillary axis. This capillary guiding of the Ne sup 7 sup + ion provides evidence that part of the ions deposit charges within the capillaries in a self-organizing process so that a considerable fraction of the ions is transmitted through the capillaries. A non-linear model is introduced to describe the essential features of the capillary guiding.

  13. Measurement of M-shell X-ray production cross-sections using 5. 96-keV photons

    Energy Technology Data Exchange (ETDEWEB)

    Garg, R.R.; Singh, S.; Shahi, J.S.; Mehta, D.; Singh, N.; Trehan, P.N. (Panjab Univ., Chandigarh (India). Dept. of Physics); Kumar, S.; Garg, M.L.; Mangal, P.C. (Panjab Univ., Chandigarh (India). Dept. of Biophysics)

    1991-04-01

    M-shell x-ray production/fluorescence (M XRF) cross-sections for five elements with 81 {le} Z {le} 92 were measured at 5.96-keV incident photon energy using thin targets. From the measured M XRF cross-sections the average M-shell fluorescence yields were derived. Experimental results for XRF cross-sections and fluorescence yields were compared with theory. The experimental results were found to be higher than the theoretical values by 10-17%. Further experimental investigations on the M XRF cross-sections for more elements at different excitation energies are required in order to check the validity of the theoretical parameters used to calculate the M XRF cross-sections. (author).

  14. Instrumentation for measurement of in-flight annihilations of 130 keV antiprotons on thin target foils

    Science.gov (United States)

    Todoroki, K.; Barna, D.; Hayano, R. S.; Aghai-Khozani, H.; Sótér, A.; Corradini, M.; Leali, M.; Lodi-Rizzini, E.; Mascagna, V.; Venturelli, L.; Prest, V.; Vallazza, L.; De Salvador, D.; Hori, M.

    2016-11-01

    We describe the instrumentation for an experiment to measure the cross sections of antiprotons with kinetic energies of 130±10 keV annihilating on carbon, palladium, and platinum target foils of sub-100 nm thicknesses. A 120 ns long pulsed beam containing 105 -106 antiprotons was allowed to traverse the foils, and the signal annihilations that resulted from this were isolated using a time-of-flight method. Backgrounds arose from Rutherford scattering of the antiprotons off the target foils, their annihilations in the target chamber walls, and π → μ → e decay of the charged pions that emerged from the annihilations. Some antiprotons slowed down and annihilated in the contamination on the target surfaces. This reduced the signal-to-background ratio of the measurement.

  15. Efficient and fast 511-keV γ detection through Cherenkov radiation: the CaLIPSO optical detector

    Science.gov (United States)

    Ramos, E.; Kochebina, O.; Yvon, D.; Verrecchia, P.; Sharyy, V.; Tauzin, G.; Mols, J. P.; Starzinski, P.; Desforges, D.; Flouzat, Ch.; Bulbul, Y.; Jan, S.; Mancardi, X.; Canot, C.; Alokhina, M.

    2016-11-01

    The CaLIPSO project aims to develop a high precision brain-scanning PET device with time-of-flight capability. The proposed device uses an innovative liquid, the TriMethyl Bismuth, as the detection medium. It detects simultaneously the ionization and optical signals from the 511 keV gamma conversion. In this paper we present the design, the Monte Carlo simulation, and the tests results for the CaLIPSO optical prototype. In this prototype we demonstrated the ability to detect efficiently the low number of the optical photons produced by the relativistic electron from the gamma conversion through the Cherenkov effect. The time resolution of the current prototype is limited by the moderate time transition spread of the PMT, but should be improved to the level better than 100 ps (FWHM) by using micro-channel-plate PMT according to the Geant 4 simulation.

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

    Science.gov (United States)

    Gliserin, Alexander; Walbran, Matthew; Baum, Peter

    2016-03-01

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

  17. Double capture in the O/sup 8+/ + He collision investigated by electron spectroscopy (80 keV, 10 deg)

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Benoit-Cattin, P.; Bordenave-Montesquieu, A.; Boudjema, M.; Gleizes, A.; Oza, D.H.; Dousson, S.; Hitz, D.

    1989-01-28

    Double capture into (3,n) autoionising states of O/sup 6+/ is observed in the O/sup 8+/ + He collision system by electron spectroscopy at 80 keV, 10/sup 0/. A comparison of the experimental results with theoretical positions and lifetimes allows the (3,3) states as well as three groups of (3,4) states to be identified. The present experimental findings are compared with earlier data for the N/sup 7+/ + He and Ne/sup 8+/(1s/sup 2/) + He systems. The influence of the core of the multicharged ion is studied by examining the O/sup 8+/ and Ne/sup 8+/(1s/sup 2/) results. The total double capture cross section is found to be large and it is compared with available experimental and theoretical data.

  18. Laser Acceleration and Deflection of 96.3 keV Electrons with a Silicon Dielectric Structure

    CERN Document Server

    Leedle, Kenneth J; Byer, Robert L; Harris, James S

    2014-01-01

    Radio frequency particle accelerators are ubiquitous in ultra-small and ultrafast science, but their size and cost has prompted exploration of compact and scalable alternatives like the dielectric laser accelerator. We present the first demonstration of high gradient laser acceleration and deflection of electrons with a silicon structure. Driven by a five nanojoule, 130 fs mode-locked Ti:Sapphire laser at 907 nm wavelength, our devices achieve accelerating gradients in excess of 200 MeV/m and sub-optical cycle streaking of 96.30 keV electrons. These results pave the way for high gradient silicon dielectric laser accelerators using commercial lasers and sub-femtosecond electron beam experiments.

  19. Reconfigurable laser ranging instrument

    Science.gov (United States)

    Schneiter, John

    1994-03-01

    This paper describes the design and operation of a fast, flexible, non-contact, eye-safe laser ranging instrument useful in a variety of industrial metrology situations, such as in-process machining control and part inspection. The system has variable computer-controlled standoff and depth of field, and can obtain 3-D images of surfaces within a range of from 1.5 ft to almost 10 ft from the final optical element. The minimum depth of field is about 3.5 in. at 1.5 ft and about 26 in. at the far range. The largest depth of field for which useful data are available is about 41 in. Resolution, with appropriate averaging, is about one part in 4000 of the depth of field, which implies a best case resolution for this prototype of 0.00075 in. System flexibility is achieved by computer controlled relative positioning of optical components.

  20. Substring Range Reporting

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li

    2014-01-01

    We revisit various string indexing problems with range reporting features, namely, position-restricted substring searching, indexing substrings with gaps, and indexing substrings with intervals. We obtain the following main results. We give efficient reductions for each of the above problems...... to a new problem, which we call substring range reporting. Hence, we unify the previous work by showing that we may restrict our attention to a single problem rather than studying each of the above problems individually. We show how to solve substring range reporting with optimal query time and little...... space. Combined with our reductions this leads to significantly improved time-space trade-offs for the above problems. In particular, for each problem we obtain the first solutions with optimal time query and O(nlog O(1) n) space, where n is the length of the indexed string. We show that our techniques...