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Sample records for kev electron micro-beam

  1. Comparative Dosimetric Estimates of a 25 keV Electron Micro-beam with three Monte Carlo Codes

    CERN Document Server

    Mainardi, E; Donahue, R J

    2002-01-01

    The calculations presented compare the different performances of the three Monte Carlo codes PENELOPE-1999, MCNP-4C and PITS, for the evaluation of Dose profiles from a 25 keV electron micro-beam traversing individual cells. The overall model of a cell is a water cylinder equivalent for the three codes but with a different internal scoring geometry: hollow cylinders for PENELOPE and MCNP, whereas spheres are used for the PITS code. A cylindrical cell geometry with scoring volumes with the shape of hollow cylinders was initially selected for PENELOPE and MCNP because of its superior simulation of the actual shape and dimensions of a cell and for its improved computer-time efficiency if compared to spherical internal volumes. Some of the transfer points and energy transfer that constitute a radiation track may actually fall in the space between spheres, that would be outside the spherical scoring volume. This internal geometry, along with the PENELOPE algorithm, drastically reduced the computer time when using ...

  2. 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...

  3. Development of 350 keV electron accelerator

    International Nuclear Information System (INIS)

    Qin Jiuchang; Cui Shan; Zhou Wenzhen; Cui Zhipeng; Shi Zhenghu; Lu Zhongcheng; Chen Shangwen; Zhang Lifeng; Cui Zongwei; Huang Jun; Yin Meng

    2007-01-01

    The 350 keV electron accelerator is used for irradiation and production of plas- tic film of the medical infusion bags. The body structure of Van de Graft accelerator and the high voltage power supply of Cockcrof-Walton accelerator are adopted in the electron accelerator. The 350 keV DC power supply is supplied by the high frequency power supply with 14 kHz and 35 kW. The body and DC power supply of the electron accelerator are installed in the tank filled with 0.3 MPa SF 6 . The electron accelerator is compact, self-shielding and suitable for on-line electron beam processing. The main characteristics of the facility are terminal voltage 370 kV, electron beam power 7 kW (350 keV/20 mA), scaning width 70 cm, irradiation dose inuniformity ≤7%. (authors)

  4. Electron bremsstrahlung spectrum, 1--500 keV

    International Nuclear Information System (INIS)

    Lee, C.M.; Kissel, L.; Pratt, R.H.; Tseng, H.K.

    1976-01-01

    Numerical data are obtained for the electron bremsstrahlung energy spectrum resulting from incident electrons of kinetic energy 1--500 keV, under the assumption that the process is described as a single-electron transition in a relativistic self-consistent screened potential, using partial-wave expansions. Comparisons with simpler analytical approximations show that these are at best of qualitative validity in this energy range. Our data are used to construct more complete tables of the spectrum by interpolation

  5. OPTIMIZATION OF OPERATION PARAMETERS OF 80-KEV ELECTRON GUN

    Directory of Open Access Journals (Sweden)

    JEONG DONG KIM

    2014-06-01

    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.

  6. A 600 keV electron radiation accelerator

    International Nuclear Information System (INIS)

    Zhou Youyi; Wang Xurong

    1995-01-01

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

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

    International Nuclear Information System (INIS)

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

    2005-01-01

    An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 μA. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure ∼10 -7 mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours

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

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, S.K. [Department of Physics, University of Pune, Pune 411007 (India); Dhole, S.D. [Department of Physics, University of Pune, Pune 411007 (India); Bhoraskar, V.N. [Department of Physics, University of Pune, Pune 411007 (India)]. E-mail: vnb@physics.unipune.ernet.in

    2005-01-01

    An electron gun consisting of cathode, focusing electrode, control electrode and anode has been designed and fabricated for the electron irradiation experiments. This electron gun can provide electrons of any energy over the range 1-20 keV, with current upto 50 {mu}A. This electron gun and a Faraday cup are mounted in the cylindrical chamber. The samples are fixed on the Faraday cup and irradiated with electrons at a pressure {approx}10{sup -7} mbar. The special features of this electron gun system are that, at any electron energy above 1 keV, the electron beam diameter can be varied from 5 to 120 mm on the Faraday cup mounted at a distance of 200 mm from the anode in the chamber. The variation in the electron current over the beam spot of 120 mm diameter is less than 15% and the beam current stability is better than 5%. This system is being used for studying the irradiation effects of 1-20 keV energy electrons on the space quality materials in which the irradiation time may vary from a few tens of seconds to hours.

  9. Deactivation of group III acceptors in silicon during keV electron irradiation

    International Nuclear Information System (INIS)

    Sah, C.; Sun, J.Y.; Tzou, J.J.; Pan, S.C.

    1983-01-01

    Experimental results on p-Si metal-oxide-semiconductor capacitors (MOSC's) are presented which demonstrate the electrical deactivation of the acceptor dopant impurity during 8-keV electron irradiation not only in boron but also aluminum and indium-doped silicon. The deactivation rates of the acceptors during the 8-keV electron irradiation are nearly independent of the acceptor impurity type. The final density of the remaining active acceptor approaches nonzero values N/sub infinity/, with N/sub infinity/(B) Al--H>In-H. These deactivation results are consistent with our hydrogen bond model. The thermal annealing or regeneration rate of the deactivated acceptors in the MOSC's irradiated by 8-keV electron is much smaller than that in the MOSC's that have undergone avalanche electron injection, indicating that the keV electron irradiation gives rise to stronger hydrogen-acceptor bond

  10. 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....

  11. 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...... the minimum represents the value closest to a bulk-yield induced by electron bombardment. It may also include contributions from the mechanisms that enhance the yield for thin and very thick films....

  12. Studies on keV and eV electrons in solids

    International Nuclear Information System (INIS)

    Schou, J.

    1979-10-01

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

  13. Electron beam dosimetry for a thin-layer absorber irradiated by 300-keV electrons

    International Nuclear Information System (INIS)

    Kijima, Toshiyuki; Nakase, Yoshiaki

    1993-01-01

    Depth-dose distributions in thin-layer absorbers were measured for 300-keV electrons from a scanning-type irradiation system, the electrons having penetrated through a Ti-window and an air gap. Irradiations of stacks of cellulose triacetate(CTA) film were carried out using either a conveyor (i.e. dynamic irradiation) or fixed (i.e. static) irradiation. The sample was irradiated using various angles of incidence of electrons, in order to examine the effect of obliqueness of electron incidence at low-energy representative of routine radiation curing of thin polymeric or resin layers. Dynamic irradiation gives broader and shallower depth-dose distributions than static irradiation. Greater obliqueness of incident electrons gives results that can be explained in terms of broader and shallower depth-dose distributions. The back-scattering of incident electrons by a metal(Sn) backing material enhances the absorbed dose in a polymeric layer and changes the overall distribution. It is suggested that any theoretical estimations of the absorbed dose in thin layers irradiated in electron beam curing must be accomplished and supported by experimental data such as that provided by this investigation. (Author)

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

    International Nuclear Information System (INIS)

    Chatterjee, S.; Agnihotri, A.; Mahtre, N.; Tribedi, L.C.; Kasthurirangan, S.

    2010-01-01

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

  15. Effects of keV electron irradiation on the avalanche-electron generation rates of three donors on oxidized silicon

    International Nuclear Information System (INIS)

    Sah, C.; Sun, J.Y.; Tzou, J.J.

    1983-01-01

    After keV electron beam irradiation of oxidized silicon, the avalanche-electron-injection generation rates and densities of the bulk compensating donor, the interface states, and the turnaround trap all increase. Heating at 200 0 C can anneal out these three donor-like traps, however, it cannot restore the generation rates back to their original and lower pre-keV electron irradiation values. The experimental results also indicate that all three traps may be related to the same mobile impurity species whose bonds are loosened by the keV electrons and then broken or released by the avalanche injected electrons

  16. 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 n......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...

  17. 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).

  18. Single-electron capture for 2-8 keV incident energy and direct scattering at 6 keV in He2+-He collisions

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, D.; Dagnac, R.

    1992-01-01

    We studied the single-electron capture as well as the direct processes occurring when a He 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 o 30' (laboratory frame). Single-electron capture into excited states of He + 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)

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

    International Nuclear Information System (INIS)

    Schou, J.

    1991-11-01

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

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

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.

    1978-01-01

    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......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...... for solid nitrogen and for the carbon substrate. For nitrogen, it varied from 0.17 el/el at 1 keV to 0.13 el/el at 3 keV, and for carbon it varied from 0.13 to 0.12. The observations are discussed and comparisons made with other theoretical and experimental results. The agreement ranges from good to fair...

  1. Single-electron capture in keV Ar15+...18++He collisions

    NARCIS (Netherlands)

    Knoop, S.; Fischer, D.; Xue, Y.; Zapukhlyak, M.; Osborne, C. J.; Ergler, Th; Ferger, T.; Braun, J.; Brenner, G.; Bruhns, H.; Dimopoulou, C.; Epp, S. W.; Martinez, A. J. Gonzalez; Sikler, G.; Orts, R. Soria; Tawara, H.; Kirchner, T.; Lopez-Urrutia, J. R. Crespo; Moshammer, R.; Ullrich, J.; Hoekstra, R.; Gonzales Martinez, A.J.

    2008-01-01

    Single-electron capture in 14 keV q(-1) Ar15+...18++He collisions is investigated both experimentally and theoretically. Partial cross sections and projectile scattering angle dependencies have been deduced from the target ion recoil momenta measured by the COLTRIMS technique. The comparison with

  2. A study on the microstructural parameters of 550 keV electron irradiated Lexan polymer films

    International Nuclear Information System (INIS)

    Hareesh, K.; Pramod, R.; Petwal, V. C.; Dwivedi, Jishnu; Sangappa; Sanjeev, Ganesh

    2012-01-01

    Lexan polymer films irradiated with 550 keV Electron Beam (EB) were characterized using Wide Angle Xray Scattering (WAXS) data to study the microstructural parameters. The crystal imperfection parameters like crystal size , lattice strain (g in %) and enthalpy (α) have been determined by Line Profile Analysis (LPA) using Fourier method of Warren.

  3. Momentum mapping spectrometer for probing the fragmentation dynamics of molecules induced by keV electrons

    International Nuclear Information System (INIS)

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

    2011-01-01

    We describe a new experimental setup for studying the fragmentation dynamics of molecules induced by the impact of keV electrons using the well-known technique of recoil ion momentum spectroscopy. The apparatus consists of mainly a time- and position-sensitive multi-hit particle detector for ion analysis and a channel electron multiplier detector for detecting the ejected electrons. Different components of the setup and the relevant electronics for data acquisition are described in detail with their working principles. In order to verify the reliable performance of the setup, we have recorded the collision-induced ionic spectra of the CO 2 molecule by the impact of keV electrons. Information about the ion pairs of CO + :O + , C + :O + and O + :O + resulting from dissociative ionizing collisions of 20 and 26 keV electrons with a dilute gaseous target of CO 2 molecules has been obtained. Under conditions of the present experiment, the momentum resolutions of the spectrometer for the combined momenta of CO + and O + ions in the direction of the time-of-flight axis and perpendicular to the direction of an electron beam are found to be 10.0 ± 0.2 and 15.0 ± 0.3 au, respectively

  4. Using the Medipix3 detector for direct electron imaging in the range 60 keV to 200 keV in electron microscopy

    Science.gov (United States)

    Mir, J. A.; Plackett, R.; Shipsey, I.; dos Santos, J. M. F.

    2017-11-01

    Hybrid pixel sensor technology such as the Medipix3 represents a unique tool for electron imaging. We have investigated its performance as a direct imaging detector using a Transmission Electron Microscope (TEM) which incorporated a Medipix3 detector with a 300 μm thick silicon layer compromising of 256×256 pixels at 55 μm pixel pitch. We present results taken with the Medipix3 in Single Pixel Mode (SPM) with electron beam energies in the range, 60-200 keV . Measurements of the Modulation Transfer Function (MTF) and the Detective Quantum Efficiency (DQE) were investigated. At a given beam energy, the MTF data was acquired by deploying the established knife edge technique. Similarly, the experimental data required to determine DQE was obtained by acquiring a stack of images of a focused beam and of free space (flatfield) to determine the Noise Power Spectrum (NPS).

  5. 150 keV intense electron beam accelerator system with high repeated pulse

    International Nuclear Information System (INIS)

    Qi, Zhang; Tixing, Li; Hongfang, Tang; Nenggiao, Xia; Zhigin, Wang; Baohong, Zheng

    1993-01-01

    A 150 keV electron beam accelerator system has been developed for wide application of high power particle beams. The new wire-ion-plasma electron gun has been adopted. The parameters are as follows: Output energy - 130-150 keV; Electron beam density - 250 mA/cm 2 ; Pulse duration - 1 μs; Pulse rate 100 pps; Section of electron beam - 5 x 50 cm 2 . This equipment can be used to study repeated pulse CO 2 laser, to be a preionizer of high power discharge excimer laser and to perform radiation curing process, and so on. The first part contains principle and design consideration. Next is a description of experimental arrangement. The remainder is devoted to describing experimental results and its application

  6. 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 calcul......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....

  7. Solar wind ∼0.1-1.5 keV electrons at quiet times

    Energy Technology Data Exchange (ETDEWEB)

    Tao, Jiawei; Wang, Linghua, E-mail: wanglhwang@gmail.com; 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. [Institute for Experimental and Applied Physics, University of Kiel (Germany)

    2016-03-25

    We present a statistical survey of the energy spectrum of solar wind suprathermal (∼0.1-1.5 keV) electrons measured by the WIND 3-D Plasma & Energetic Particle (3DP) instrument at 1 AU during quiet times at the minimum and maximum of solar cycles 23 and 24. Firstly, we separate strahl (beaming) electrons and halo (isotropic) electrons based on their features in pitch angle distributions. Secondly, we fit the observed energy spectrum of both the strahl and halo electrons at ∼0.1-1.5 keV to a Kappa distribution function with an index κ, effective temperature T{sub eff} and density n{sub 0}. We also integrate the the measurements over ∼0.1-1.5 keV to obtain the average electron energy E{sub avg} of the strahl and halo. We find a strong positive correlation between κ and T{sub eff} for both the strahl and halo, possibly reflecting the nature of the generation of these suprathermal electrons. Among the 245 selected samples, ∼68% have the halo κ smaller than the strahl κ, while ∼50% have the halo E{sub h} larger than the strahl E{sub s}.

  8. 3 to 15 keV Ar+ induced Auger electron emission from Si and Ar

    International Nuclear Information System (INIS)

    Kempf, J.; Kaus, G.

    1977-01-01

    Ar + induced Auger electrons from Si and Ar were investigated at bombardment energies between 3-15 keV and target currents of a few μA. The Auger electron yields were compared with secondary ion yields of Si and Ar by simultaneous SIMS-AES measurements. In the ion induced Auger spectra of Si five Auger peaks and in the Ar spectra three Auger peaks were observed. The ion induced Auger electron yield of Si and Ar were found to be strongly dependent upon the primary ion energy. 'Bulk like' and 'atomic like' Auger transitions of ion induced Auger electrons of Si were observed. (orig.) [de

  9. Cusp electron production in 75--300 keV He+ + Ar collisions

    International Nuclear Information System (INIS)

    Plano, V.L.; Sarkadi, L.; Zavodszky, P.; Berenyi, D.; Palinkas, J.; Gulyas, L.; Takacs, E.; Toth, L.; Tanis, J.A.

    1992-01-01

    Cusp-electron production has been investigated in collisions of 75--300 keV He + with Ar. The relative contributions from electron capture to the continuum (ECC), transfer ionization (TI), and electron loss to the continuum (ELC) to the total cusp electron production were measured. Over the energy range investigated, ECC was found to decrease from about 86% to 80%, TI decreased from about 12% to 1%, and ELC increased from about 2% to 20%. The present results are consistent with earlier work for He + and O q+ projectiles

  10. The bremsstrahlung induced by 0.3-2 keV electron scattering by Ar atoms

    International Nuclear Information System (INIS)

    Gnatchenko, E.V.; Tkachenko, A.A.; Verkhovtseva, E.T.

    2002-01-01

    The differential spectra of a bremsstrahlung resulting from a 0.3-2 keV electron scattering by Ar atoms are studied. Photon energies within the ultrasoft X-ray band from 124 to 190.8 eV, which is characterized by the low dynamic polarizability of the Ar atom, are considered. For the entire spectrum of photon energies (124-190.8 eV), the intensity of the bremsstrahlung differential spectra first grows with an increase in the electron energy from 0.3 to 0.7 keV and then decreases as the electron energy increases from 0.7 to 2 keV. The increase in intensity is directly proportional, and the decrease is inversely proportional to the square root of the energy of the scattered electrons. Within the context of a 'low-energy' approximation, the increase in the number of photons with the electron energy is due to the contribution of the atomic excitation and ionization channels being available during the bremsstrahlung process

  11. Construction of an electron accelerator of 20 KeV: application in the polymeric study

    International Nuclear Information System (INIS)

    Sandonato, G.M.

    1983-01-01

    A low energy electron accelerator (maximum energy 20 KeV) is constructed. A black and white kinescope electron gun, with a single thermionic emitter was used as electron source. The energy of electron beam can be changed continuously from 0 to 20 KeV. The intensity of the current can be changed from a minimum of 10 -12 A to a maximum of 3 μA, and can be mantained contant in time after its value has been fixed. The irradiated area can be changed from a diameter of 1 milimeter to a maximum of 6 centimeter, by focalizing or defocalizing the image of electron beam. The final pressure reached in vacuum chambers was 10 -7 Torr. During operation the surface of cathode of electron gun is damaged by ion bombardeament. The degree of damage can be checked if the cathode image is focalized and examined on a luminescent screen. The accelerator was used to study electron irradiation effects in Teflon, employing the method of the split Faraday cup. Transient charging and discharging currents were measured. The average range of electrons of the electrons and the induced conductivity were determined. (Author) [pt

  12. Compton scattering of 145 keV gamma rays by K-shell electrons of silver

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, V B; Singh, B; Ghumman, B S [Punjabi Univ., Patiala (India). Dept. of Physics

    1981-01-01

    Differential cross-sections for the incoherent scattering of 145 keV photons from K-shell electrons of silver are measured at scattering angles ranging from 30/sup 0/ to 150/sup 0/ to investigate the effect of electron binding on the scattering process in the low energy region. Measurements are made employing two NaI (Tl) scintillation spectrometers and a slow-fast coincidence circuit of resolving time 30 ns. The experimental results are compared with the available theoretical data. The total K-shell scattering cross-section is also estimated and is about 45% of the free electron cross-section.

  13. First experiments with the 200 keV electron beam ion trap at LLNL

    International Nuclear Information System (INIS)

    Marrs, R.E.; Knapp, D.A.; Elliott, S.

    1993-01-01

    A high-energy electron beam ion trap (Super EBIT) is operating at electron energies up to 200 keV and currents up to 200 mA. Highly charged ions up to Li-like U 89+ and H-like Pb 81+ have been produced and studied. Ionization cross sections for H-like Dy 66+ at E e = 170 keV have been measured with respect to radiative recombination from the observed Dy 66+ /Dy 67+ equilibrium ionization balance. A Bragg crystal spectrometer has been used to measure 2s 1/2 -2p 3/2 transition energies in Li-like U 82+ with respect to the Lymann-series transitions in lower-Z hydrogenic ions

  14. 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 ...... are present within the dosimeter. (C) 2005 Elsevier Ltd. All rights reserved....

  15. Radiation damage studies on STAR250 CMOS sensor at 300 keV for electron microscopy

    International Nuclear Information System (INIS)

    Faruqi, A.R.; Henderson, R.; Holmes, J.

    2006-01-01

    There is a pressing need for better electronic detectors to replace film for recording high-resolution images using electron cryomicroscopy. Our previous work has shown that direct electron detection in CMOS sensors is promising in terms of resolution and efficiency at 120 keV [A.R. Faruqi, R. Henderson, M. Prydderch, R. Turchetta, P. Allport, A. Evans, Nucl. Instr. and Meth. 546 (2005) 170], but in addition, the detectors must not be damaged by the electron irradiation. We now present new measurements on the radiation tolerance of a 25 μm pitch CMOS active-pixel sensor, the STAR250, which was designed by FillFactory using radiation-hard technology for space applications. Our tests on the STAR250 aimed to establish the imaging performance at 300 keV following irradiation. The residual contrast, measured on shadow images of a 300 mesh grid, was >80% after corrections for increased dark current, following irradiation with up to 5x10 7 electrons/pixel (equivalent to 80,000 electron/μm 2 ). A CMOS sensor with this degree of radiation tolerance would survive a year of normal usage for low-dose electron cryomicroscopy, which is a very useful advance

  16. Multiple capture investigated by coincident electron spectroscopy in X7++Ar, at 70 keV

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.

    1999-01-01

    The multiple electron capture in N 7+ + Ar and F 7+ (1s 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 7+ + Ar collisions. (orig.)

  17. The generation of high-power charge particle micro beams and its interaction with condensed matter

    International Nuclear Information System (INIS)

    Vogel, N.; Skvortsov, V.A.

    1996-01-01

    As has been observed experimentally, the action of a picosecond laser beam on an Al-target in air gives rise to the generation and acceleration of high-power micro electron and ion beams. An original theoretical model for describing the generation and particle acceleration of such micro beams as a result of the micro channeling effect is presented. It was found that extreme states of matter, with compression in the Gbar pressure range, can be produced by such micro beams. (author). 3 figs., 12 refs

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

    DEFF Research Database (Denmark)

    Miller, A.; Helt-Hansen, J.

    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....... However, dose gradients within the dosimeters, when it is irradiated at low electron energies,mean that calibration function here will depend on both irradiation energy and the required effective point of measurement of the dosimeter. These are general effects that apply to any dosimeter that has a non...

  19. Effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV

    International Nuclear Information System (INIS)

    Prasannakumar, S.; Umesh, T.K.

    2014-01-01

    The effective atomic number and effective electron densities of some inorganic compounds for Compton effect in the gamma energy range 280 keV to 1115 keV by using Compton scattering cross sections which are determined on a goniometer assembly. An ORTEC model 23210 gamma-x high purity germanium detector (HpGe) has been used to record the data along with a personal computer based MCA in the angular region 50°-110°. The effective atomic numbers so obtained were found to be equal to the total number of electrons present in the sample in accordance with the chemical formula. The results so obtained are of first of their kind at these energies and are expected to be important in a variety of applications of radiation physics and chemistry. (author)

  20. Incoherent scattering of gamma rays by K-shell electrons. [Differential cross sections, 145 to 662 KeV

    Energy Technology Data Exchange (ETDEWEB)

    Spitale, G.C.; Bloom, S.D.

    1976-05-12

    Differential cross sections for incoherent scattering by K-shell electrons were measured, using coincidence techniques, for incident photons having energies of 662 keV, 320 keV, and 145 keV. The spectral distributions of the scattered photons emerging at scattering angles from 20/sup 0/ to about 140/sup 0/ are reported. Target materials were iron, tin, holmium, and gold at 320 keV; tin and gold at 662 keV; and iron and tin at 145 keV. A typical energy spectrum consists of a scattered peak that is much narrower than would be expected from the bound state electron motion. The peak also, typically, reaches a broad maximum width for scattering angles between 45/sup 0/ and 60/sup 0/. Rather than monotonically increasing with atomic number the peak width reaches a broad maximum, generally, between Z = 50 and Z = 67, and then decreases with increasing atomic number. No Compton defect appears in any of the peaks to within +- 20 keV. A discussion of the expected magnitude of the Compton defect is included. The peak is superimposed on a continuum that diverges at the low end of the scattered photon spectrum for the following cases: gold, holmium, and tin targets for 320-keV incident photons; gold and possibly tin targets for 662-keV photons incident. This infrared divergence is expected on theoretical grounds and has been predicted. It is very nearly isotropic.

  1. Efficient scattering of electrons below few keV by Time Domain Structures around injection fronts

    Science.gov (United States)

    Vasko, I.; Agapitov, O. V.; Mozer, F.; Artemyev, A.; Krasnoselskikh, V.

    2016-12-01

    Van Allen Probes observations show an abundance of non-linear large-amplitude electrostatic spikes around injection fronts in the outer radiation belt. These spikes referred to as Time Domain Structures (TDS) include electron holes, double layers and more complicated solitary waves. The electron scattering driven by TDS may not be evaluated via the standard quasi-linear theory, since TDS are in principle non-linear plasma modes. In this paper we analyze the scattering of electrons by three-dimensional TDS (with non-negligible perpendicular electric field) around injection fronts. We derive the analytical formulas describing the local scattering by single TDS and show that the most efficiently scattered electrons are those in the first cyclotron resonance (electrons crossing TDS on a time scale comparable with their gyroperiod). The analytical formulas are verified via the test-particle simulation. We compute the bounce-averaged diffusion coefficients and demonstrate their dependence on the TDS spatial distribution, individual TDS parameters and L shell. We show that TDS are able to provide the pitch-angle scattering of <5 keV electrons at rate 10-2-10-4 s-1 and, thus, can be responsible for driving loss of electrons out of injections fronts on a time scale from few minutes to few hours. TDS can be, thus, responsible for driving diffuse aurora precipitations conjugated to injection fronts. We show that the pitch-angle scattering rates driven by TDS are comparable with those due to chorus waves and exceed those due to electron cyclotron harmonics. For injections fronts with no significant wave activity in the frequency range corresponding to chorus waves, TDS can be even dominant mechanism for losses of below few keV electrons.

  2. Interface-mediated amorphization of coesite by 200 keV electron irradiation

    International Nuclear Information System (INIS)

    Gong, W.L.; Wang, L.M.; Ewing, R.C.; Xie, H.S.

    1997-01-01

    Electron-induced amorphization of coesite was studied as a function of irradiation temperature by in situ transmission electron microscopy at an incident energy of 200 keV. Electron-induced amorphization of coesite is induced by an ionization mechanism and is mainly dominated by an interface-mediated, heterogeneous nucleation-and-growth controlled process. Amorphous domains nucleate at surfaces, crystalline-amorphous (c-a) interfaces, and grain boundaries. This is the same process as the interface-mediated vitrification of coesite by isothermal annealing above the thermodynamic melting temperature (875 K), but below the glass transition temperature (1480 K). The interface-mediated amorphization of coesite by electron irradiation is morphologically similar to interface-mediated thermodynamic melting. copyright 1997 American Institute of Physics

  3. Solar Wind 0.1-1 keV Electrons in the Corotating Interaction Regions

    Science.gov (United States)

    Wang, L.; Tao, J.; Li, G.; Wimmer-Schweingruber, R. F.; Jian, L. K.; He, J.; Tu, C.; Tian, H.; Bale, S. D.

    2017-12-01

    Here we present a statistical study of the 0.1-1 keV suprathermal electrons in the undisturbed and compressed slow/fast solar wind, for the 71 corotating interaction regions (CIRs) with good measurements from the WIND 3DP and MFI instruments from 1995 to 1997. For each of these CIRs, we separate the strahl and halo electrons based on their different behaviors in pitch angle distributions in the undisturbed and compressed solar wind. We fit both the strahl and halo energy spectra to a kappa function with an index κ index and effective temperature Teff, and calculate the pitch-angle width at half-maximum (PAHM) of the strahl population. We also integrate the electron measurements between 0.1 and 1.0 keV to obtain the number density n and average energy Eavg for the strahl and halo populations. We find that for both the strahl and halo populations within and around these CIRs, the fitted κ index strongly correlates with Teff, similar to the quiet-time solar wind (Tao et al., ApJ, 2016). The number density of both the strahl and halo shows a strong positive correlation with the electron core temperature. The strahl number density ns is correlated with the magnitude of interplanetary magnetic field, and the strahl PAHM width is anti-correlated with the solar wind speed. These results suggest that the origin of strahl electrons from the solar corona is likely related to the electron core temperature and magnetic field strength, while the production of halo electrons in the interplanetary medium could depend on the solar wind velocity.

  4. Effect of irradiation with <200 keV electrons on AG-80 resin

    Energy Technology Data Exchange (ETDEWEB)

    Gao Yu [School of Materials Science and Engineering, Harbin Institute of Technology, 432 Heilongjiang province, Harbin 150001 (China)]. E-mail: czq04@yahoo.com.cn; Jiang Shengling [College of Materials Science and Engineering, Beijing University of Chemical Technology, Beijing 100029 (China); Sun Mingren [School of Materials Science and Engineering, Harbin Institute of Technology, 432 Heilongjiang province, Harbin 150001 (China); Yang Dezhuang [School of Materials Science and Engineering, Harbin Institute of Technology, 432 Heilongjiang province, Harbin 150001 (China); He Shiyu[School of Materials Science and Engineering, Harbin Institute of Technology, 432 Heilongjiang province, Harbin 150001 (China); Li Zhijun [39th Institute, China Electronic Science and Technology Groups Inc., Xi-an 710065 (China)

    2005-08-01

    AG-80 resin, namely tetraglycidyl diaminodiphenyl methane (TGDDM), is a new type of thermosetting matrix for advanced carbon/epoxy composites, which was irradiated with electrons of 160 keV. The results show that by increasing the fluence to 6.3x10{sup 15} cm{sup -2}, the mass loss ratio ascends dramatically and then tends to level off. The mass loss behavior can be attributed to the combined effects of the formation of gaseous radiolytic products and a degraded layer, the surface ablation due to discharging and the skin carbon enrichment.

  5. Radiation vulcanization of natural rubber latex using 250 keV electron beam machine

    Energy Technology Data Exchange (ETDEWEB)

    Chirinos, H.; Yoshii, F.; Makuuchi, K.; Lugao, A. E-mail: ablugao@net.ipen.br

    2003-08-01

    The sensitized radiation vulcanization of natural rubber latex has been carried out with 250 keV electrons. Latex was irradiated over a range of the beam current from 5 to 20 mA in the presence of sensitizers like the n-butyl acrylate (n-BA). The vulcanization dose decreases with increasing beam current condition. The rate of vulcanization (R{sub vul}) depends on the beam current (I) as given by the equation R{sub vul}=kI{sup 0.6}.

  6. Compton scattering of 145 keV photons from bound electrons of tin and molybdenum

    Energy Technology Data Exchange (ETDEWEB)

    Ghumman, B S; Acharya, V B; Singh, B [Punjabi Univ., Patiala (India). Dept. of Physics

    1981-10-28

    Differential cross sections for Compton scattering of 145 keV gamma rays from K-shell electrons of tin and molybdenum are measured at scattering angles in the range 30 to 150/sup 0/. Measurements are made employing NaI(Tl) detectors and a coincidence set up with resolving time approximately equal to 30 ns. The experimental results are compared with the available theoretical data. The total cross section is estimated to be about 0.43 sigmasub(F) for tin and 0.41 sigmasub(F) for molybdenum.

  7. Effects of electronic excitation in 150 keV Ni ion irradiation of metallic systems

    Science.gov (United States)

    Zarkadoula, Eva; Samolyuk, German; Weber, William J.

    2018-01-01

    We use the two-temperature model in molecular dynamic simulations of 150 keV Ni ion cascades in nickel and nickel-based alloys to investigate the effect of the energy exchange between the atomic and the electronic systems during the primary stages of radiation damage. We find that the electron-phonon interactions result in a smaller amount of defects and affect the cluster formation, resulting in smaller clusters. These results indicate that ignoring the local heating due to the electrons results in the overestimation of the amount of damage and the size of the defect clusters. A comparison of the average defect production to the Norgett-Robinson-Torrens (NRT) prediction over a range of energies is provided.

  8. Angular distribution of ejected electrons from 20 keV He+ impact on He

    International Nuclear Information System (INIS)

    Tokoro, N.; Takenouchi, S.; Urakawa, J.; Oda, N.

    1982-01-01

    The angular distributions of ejected electrons in the energy range 5-70 eV have been measured at angles from 30 to 150 0 for 20 keV He + impact on He. The angular dependence of excitation cross sections of autoionisation states 2s 2 1 S and 2p 2 1 D+2s2p 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 0 in the laboratory frame for low-energy electrons (< approximately equal to 30 eV). These angular distributions are discussed in connection with the molecular autoionisation mechanism. (author)

  9. 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 (

  10. Calculation of W for low energy electrons in tissue-equivalent gas. [<10 keV

    Energy Technology Data Exchange (ETDEWEB)

    Dayashankar, [Bhabha Atomic Research Centre, Bombay (India). Div. of Radiation Protection

    1977-11-01

    The mean energy expended per ion pair formed (W-value) in the tissue-equivalent gas for incident electrons of energy up to 10 keV has been calculated in the continuous slowing-down approximation. The effect of secondary and tertiary electrons has been considered by utilizing recent measurements of Opal et al., (1971, J. Chem. Phys., 55,4100) on the energy spectra of low-energy secondary electrons and the Mott formula for the spectra of high-energy secondaries. The results, which are provisional in nature due to the limitations on the accuracy of the input cross-section data and the neglect of the discrete nature of energy loss process, are compared with the available measurements.

  11. Inactivation of catalase monolayers by irradiation with 100 keV electrons

    International Nuclear Information System (INIS)

    Hahn, M.; Seredynski, J.; Baumeister, W.

    1976-01-01

    A catalase monolayer adsorbed on a layer of arachidic acid deposited on a solid support was irradiated with 100 keV electrons simulating the conditions of electron microscopic imaging. Effective doses were calculated taking into account the angular and energy distribution of backscattered electrons. Enzymatic inactivation was chosen as the criterion for damage and was monitored by a rapid and quantifiable but nevertheless sensitive assay. Dose-response curves revealed that inactivation is a one-hit--multiple-target phenomenon, which is consistent with biochemical evidence for a cooperative function of subunits. The experimentally determined target size coincides fairly well with both calculated cross sections for inelastic interactions based on the atomic composition of catalase and with calculated cross sections for ionizing events based on the chemical bonds involved. This legitimates both types of calculations even for complex biomolecules

  12. Radiation defect distribution in silicon irradiated with 600 keV electrons

    International Nuclear Information System (INIS)

    Hazdra, P.; Dorschner, H.

    2003-01-01

    Low-doped n-type float zone silicon was irradiated with 600 keV electrons to fluences from 2x10 13 to 1x10 15 cm -2 . Radiation defects, their introduction rates and full-depth profiles were measured by two complementary methods - the capacitance deep level spectroscopy and the high-voltage current transient spectroscopy. Results show that, in the vicinity of the anode junction, the profile of vacancy-related defect centers is strongly influenced by electric field and an excessive generation of vacancies. In the bulk, the slope of the profile can be derived from the distribution of absorbed dose taking into the account the threshold energy necessary for Frenkel pair formation and the dependency of the defect introduction rate on electron energy

  13. The quiet time structure of energetic (35--560 keV) radiation belt electrons

    International Nuclear Information System (INIS)

    Lyons, L.R.; Williams, D.J.

    1975-01-01

    Detailed Explorer 45 equatorial observations of the quiet time structure of radiation belt electrons (35--560 keV) for 1.7approximately-less-thanLapproximately-less-than5.2 are presented. Throughout the slot region and outer regions of the plasmasphere the observed pitch angle distributions are found to agree with those expected from resonant interactions with the plasmaspheric whistler mode wave band. Coulomb collisions become the dominant loss mechanism within the inner zone. The overall two-zone structure of the observed radial profiles is found to agree with the equilibrium structure expected to result from a balance between pitch angle scattering losses and radial diffusion from an average outer zone source. This agreement suggests that the dominant quiet time source and loss mechanisms have been identified and evaluated for energetic radiation belt electrons within the plasmasphere. In the outer regions of the plasmasphere (Lapprox.5) the equilibrium structure is observed to be modified by daily flux variations associated with changes in the level of magnetic activity that occur even during relatively quiet times. Within the inner region of the plasmasphere (Lapproximately-less-than3.5), electron fluxes are decoupled from these magnetic activity variations by the long time scales (>10 days) required for pitch angle and radial diffusion. Consequently, fluxes of these electrons are observed to remain nearly constant at equilibrium levels throughout the quiet periods examined

  14. The Preparation of an Electron Beam Machine 500 keV/10 mA Instrumentation

    International Nuclear Information System (INIS)

    Sudiyanto; Prayitno; Dewita; Bambang-Supardiyono; Widi-Setyawan

    2000-01-01

    The preparation of an Electron Beam Machine 500 keV/10 mA instrumentation by using a Distributed Instrumentation System have been done. The system consisting of industrial interfaces PCL-718 ADC 12 bit, PCLD-889 Mux/Prog Gain Amp PCLD-786 Driver Relay with solid state relays, PCL 745 serial com, DC motor 12-24 V/8.6 A with reduction gear 10:1 and a pair of PC's connected with twisted cable and an isolated amplifier AD-210 equipped with high voltage divider. The operation can be done using animation Pascal program on the remote mode using twisted cable and a pair of RS-485 interfaces, some operation sequences such as switch on/off blower unit, water pump cooling unit, filament voltage, anode voltage and some timer's have already been adapted on the computer program. Non intercepting beam monitoring technique have been discussed in this paper. (author)

  15. The detection of hard x-rays (10-140 KeV) by channel plate electron multipliers

    International Nuclear Information System (INIS)

    Bateman, J.E.

    1976-12-01

    Results are presented indicating that hard X-rays in the energy range 10 to 50 keV can be detected with good efficiency (5 to 10%) in channel plate electron multipliers (CPEM). From 50 keV to 140 keV the detection efficiency lies in the range 1 to 2%. A simple physical model is developed which indicates that not only can good detection efficiency be obtained but that very good X-ray imaging is possible. The model predicts that with further development, a wideband, hard X-ray detector can be realised with a detection efficiency in the range 5 to 20% and spatial response better than 10 lp/mm in the energy range 10 to 140 keV. (author)

  16. 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.

  17. Pitch angle distributions of > 30 keV electrons at geostationary altitudes

    International Nuclear Information System (INIS)

    Higbie, P.R.; Baker, D.N.; Hones, E.W. Jr.; Belian, R.D.

    1978-01-01

    The satellites 1976-059A and 1977-007A each carry energetic particle detectors which measure fluxes of electrons in the 30 to 300 keV energy range. Five separate sensors mounted at 30, 60, 90, 120, and 150 0 to the spacecraft spin axis provide two hundred samples of the three dimensional distribution function for every ten second spacecraft rotation. Spherical harmonic functions up to the fourth order were fit to the observed pitch angle distributions. The second and fourth order coefficients obtained for these fits were averaged for each hour of local time. The probability distributions for the averaged harmonic coefficients were calculated and are presented as a function of local time. Possible relations of these distributions to interplanetary conditions are discussed. Using the present analysis techniques, the intensity of electrons at the noon meridian is derived as a function of pitch angle and radial distance and is given by j(α,r) = 2.03 x 10 8 (0.49 sin 4 . 78 α + 0.51 sin 0 . 27 α) e/sup -r/1.60/ el/cm 2 sec sr. 11 references

  18. Dose intercomparison for 400–500 keV electrons using FWT-60 film and glutamine (spectrophotometric readout) dosimeters

    DEFF Research Database (Denmark)

    Gupta, B. L.; Nilekani, S. R.; Gehringer, P.

    1986-01-01

    This paper describes the dose and the depth dose measurements with FWT-60 film and glutamine (Spectrophotometric readout) dosimeters for 400–500 keV electrons. The glutamine powder was spread uniformly in polyethylene bags and the powder thickness in each bag was 5 mg cm−2. Both techniques show...

  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. Single-electron capture into Ar+ excited states in Ar2 + Na collision below 12 keV, 1

    International Nuclear Information System (INIS)

    Matsumoto, Atsushi; Tsurubuchi, Seiji; Okuno, Kazuhiko; Ohtani, Shunsuke; Iwai, Tsuruji.

    1979-08-01

    Emission spectra between 2800 and 6000 A have been observed at the ionic energies from 0.2 to 12 keV. Absolute measurements of emission cross-sections have been made for the emission lines coming from ArII excited states at 4 and 8 keV with a crossed-beam technique. Processes of single-electron capture into the ArII 4p- and 4p'-states, with exothermicity of a few eV, take place dominantly (--10 15 cm 2 ), while the endothermic processes producing ArII in the 4d- and 5s-states occur with small cross-sections. Sum of the cross-sections for electron capture into the excited states observed is comparable with the total single-electron capture cross-section estimated from attenuation measurements of ion currents. Possible errors and uncertainties are discussed. (author)

  1. Single-electron capture into Ar+ excited states in Ar2++Na collision below 12 keV, 1

    International Nuclear Information System (INIS)

    Matsumoto, Atsushi; Tsurubuchi, Seiji; Iwai, Tsuruji; Ohtani, Shunsuke; Okuno, Kazuhiko

    1980-01-01

    Emission spectra between 2800 and 6000 A have been observed at the ionic energies from 0.2 to 12 keV. Absolute measurements of emission cross-sections have been made for the emission lines coming from ArII excited states at 4 and 8 keV with a crossed-beam technique. Processes of single-electron capture into the ArII 4p- and 4p'-states, with exothermicity of a few eV, take place dominantly (--10 -15 cm 2 ), while the endothermic processes producing ArII in the 4d- and 5s-states occur with small cross-sections. Sum of the cross-sections for electron capture into the excited states observed is comparable with the total single-electron capture cross-section estimated from attenuation measurements of ion currents. Possible errors and uncertainties are discussed. (author)

  2. 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)

  3. Synthesis of gold and silver nanoparticles by electron irradiation at 5-15 keV energy

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, S K; Bogle, K A; Dhole, S D; Bhoraskar, V N [Microtron Accelerator Laboratory, Department of Physics, University of Pune, Pune-411007 (India)

    2007-04-04

    Thin coatings ({approx}10 {mu}m) made from a mixture of polyvinyl alcohol (PVA) and HAuCl{sub 4} or PVA and AgNO{sub 3} on quartz plates were irradiated with 5-15 keV electrons, at room temperature. The electron energy was varied from coating to coating in the range of 5-15 keV, but electron fluence was kept constant at {approx}10{sup 15} e cm{sup -2}. Samples were characterized by the UV-vis, XRD, SEM and TEM techniques. The plasmon absorption peaks at {approx}511 and {approx}442 nm confirmed the formation of gold and silver nanoparticles in the respective electron-irradiated coatings. The XRD, SEM and TEM measurements reveal that the average size of the particles could be tailored in the range of 130-50 nm for gold and from 150-40 nm for silver by varying the electron energy in the range of 5-15 keV. These particles of gold and silver embedded in the polymer could also be separated by dissolving the coatings in distilled water.

  4. Production of Mg and Al Auger electrons by noble gas ion bombardment of Mg and Al surfaces. [3 KeV, electron promotion

    Energy Technology Data Exchange (ETDEWEB)

    Ferrante, J; Pepper, S V [National Aeronautics and Space Administration, Cleveland, Ohio (USA). Lewis Research Center

    1976-08-01

    In this letter the relative production efficiency of Mg and Al Auger electrons by He, Ne, Ar, Kr and Xe ion bombardment as a function of ion energy (<=3 keV) is reported. Some comments on the interpretation of the results in terms of electron promotion are also given.

  5. Variable Gap Undulator for 1.5-48 Kev Free Electron Laser at Linac Coherent Light Source

    International Nuclear Information System (INIS)

    2011-01-01

    We study the feasibility of generating femtosecond duration Free-Electron Laser with a variable photon energy from 1.5 to 48 keV, using an electron bunch with the same characteristics of the LINAC Coherent Light Source (LCLS) bunch, and a planar undulator with additional focusing. We assume that the electron bunch energy can be changed, and the undulator has a variable gap, allowing a variable undulator parameter. It is assumed to be operated in an ultra-low charge and ultra-short pulse regime. We study the feasibility of a tunable, short pulse, X-ray FEL with photon energy from 1.5 to 48 keV, using an electron beam like the one in the LCLS and a 2:5 cm period, variable gap, planar undulator. The beam energy changes from 4.6 to 13.8 GeV, the electorn charge is kept at 10 pC, and the undulator parameter varies from 1 to 3. The undulator length needed to saturate the 48 keV FEL is about 55 m, with a peak power around 5 GW. At longer wavelength the saturation length is as short as 15 m, and the peak power around 20 GW. The results from the analytical models and the GENESIS simulations show that the system is feasible. The large wavelength range, full tunability and short, few femtosecond pulses, together with the large peak power, would provide a powerful research tool.

  6. 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)

  7. Quiet-time Suprathermal (~0.1-1.5 keV) Electrons in the Solar Wind

    Science.gov (United States)

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

    2016-03-01

    We present a statistical survey of the energy spectrum of solar wind suprathermal (˜0.1-1.5 keV) electrons measured by the WIND 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 Teff. We also calculate the number density n and average energy Eavg 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 Teff 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).

  8. Measurement of differential incoherent scattering cross-sections of 145 keV photons from K-shell electrons

    Energy Technology Data Exchange (ETDEWEB)

    Acharya, V B; Ghumman, B S [Punjabi Univ., Patiala (India). Dept. of Physics

    1980-06-01

    Differential cross-sections for incoherent scattering of 145 keV photons from K-shell electrons of tin, silver and molybdenum have been measured at 110deg to investigate the effect of electron binding on differential cross-sections in the low energy region. The incoherent scattered photons are selected in coincidence with X-rays which follow the vacancies caused by the ejection of the electrons. NaI(Tl) scintillators are used for the detection of scattered photons and emitted X-rays. The experimental results are compared with the available theoretical data.

  9. Growth and decay of surface voltage on silver diffused polyimide exposed to 3-15 keV electrons

    Energy Technology Data Exchange (ETDEWEB)

    Mahapatra, S K; Dhole, S D; Bhoraskar, V N [Department of Physics, University of Pune, Pune-411007 (India)

    2007-02-21

    During electron irradiation, the growth in the surface voltage on virgin and silver diffused polyimide sample was studied by varying electron energy from 3 to 15 keV and beam diameter from 3 to 15 mm. At a constant beam current, the surface voltage increased nonlinearly with electron energy but decreased slowly with beam diameter at fixed electron energy. At a surface voltage around saturation or beyond 3 kV, the electron beam was switched off and the decay in the surface voltage was studied for a period of 9 x 10{sup 4} s. The surface analysis revealed that the relative concentrations of carbon increased and that of the oxygen and the nitrogen decreased in the electron irradiated virgin and silver diffused polyimide sample, however in different proportions. Under the identical conditions of electron irradiation, the growth rate of the surface voltage, the post irradiated surface resistivity and the voltage decay constant of the silver diffused polyimide were lower than that of the virgin polyimide. The results of the present study reveal that the resistance of the silver diffused polyimide to keV electrons is higher than that of the virgin polyimide.

  10. Determination of Penetration Depth of 800 keV Electron Beam into Coal Fired Power Plant Flue Gas at in a Electron Beam Machine Flue Gas Treatment System

    International Nuclear Information System (INIS)

    Rany Saptaaji

    2008-01-01

    Penetration depth calculation of 800 keV electron beam into flue gas from coal fired power plan is presented in this paper. Electron Beam for Flue Gas Treatment (EB-FGT) is a dry treatment process using electron beam to simultaneously reduce SO 2 and NO x . Flue gas irradiation produces active radicals and then reaction with SO 2 and NO x produces nitrate acid and sulphate acid. Process vessel is needed in this process as reaction container of flue gas with electron beam. The calculation of electron beam penetration depth into flue gas is used to determine the process vessel dimension. The result of calculation of optimum penetration depth of 800 keV electron beam into flue gas is 188.67 cm. (author)

  11. 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.

  12. 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.

  13. Monte-Carlo simulations of secondary electron emission from CsI, induced by 1-10 keV X-rays and electrons

    International Nuclear Information System (INIS)

    Akkerman, A.; Gibrekhterman, A.; Breskin, A.; Chechik, R.

    1992-05-01

    A model for electron transport and emission in CsI is proposed. It is based on theoretically calculated microscopic cross-sections for electron interaction with the nuclear and the electronic components of the solid. A Monte Carlo program based on this model was developed to simulate secondary electron emission induced by X-rays and electrons in the energy range of 1 to 10 keV. The calculated secondary emission yields agree with existing experimental data. The model provides all necessary characteristics for the design of radiation detectors based on secondary electron emission. It can be expanded to higher incident energies and other alkali halides. (author)

  14. Testing and Comparison of Imaging Detectors for Electrons in the Energy Range 10-20 keV

    Science.gov (United States)

    Matheson, J.; Moldovan, G.; Kirkland, A.; Allinson, N.; Abrahams, J. P.

    2017-11-01

    Interest in direct detectors for low-energy electrons has increased markedly in recent years. Detection of electrons in the energy range up to low tens of keV is important in techniques such as photoelectron emission microscopy (PEEM) and electron backscatter diffraction (EBSD) on scanning electron microscopes (SEMs). The PEEM technique is used both in the laboratory and on synchrotron light sources worldwide. The ubiquity of SEMs means that there is a very large market for EBSD detectors for materials studies. Currently, the most widely used detectors in these applications are based on indirect detection of incident electrons. Examples include scintillators or microchannel plates (MCPs), coupled to CCD cameras. Such approaches result in blurring in scintillators/phosphors, distortions in optical systems, and inefficiencies due the limited active area of MCPs. In principle, these difficulties can be overcome using direct detection in a semiconductor device. Growing out of a feasibility study into the use of a direct detector for use on an XPEEM, we have built at Rutherford Appleton Laboratory a system to illuminate detectors with an electron beam of energy up to 20 keV . We describe this system in detail. It has been used to measure the performance of a custom back-thinned monolithic active pixel sensor (MAPS), a detector based on the Medipix2 chip, and a commercial detector based on MCPs. We present a selection of the results from these measurements and compare and contrast different detector types.

  15. Monochromaticity of optical radiation of Smith-Purcell generated by electron beam with 75 keV energy

    International Nuclear Information System (INIS)

    Adishchev, Yu.N.; Vukolov, A.V.; Karlovets, D.V.; Potylitsyn, A.P.; Kube, G.

    2005-01-01

    The monochromatism of the Smith-Purcell optical radiation generated by a 75-keV electron beam with a final emittance of ε = 0.65 x 10 -4 mm rad that passes over an optical grating with a period of D = 0.833 μm has been analyzed. It has been shown that the monochromatism (line width) of the Smith-Purcell radiation is determined not only by the angular aperture of a monochromator but also by the divergence of the electron beam [ru

  16. A new method to measure and increase the detection efficiency of a microchannel plate for 100 keV electrons

    International Nuclear Information System (INIS)

    Tornow, R.P.

    1990-01-01

    A new method is described which permits measurement of efficiency of a microchannel plate (MCP) simply by tracing the output current pulse in the saturated mode. The dependence of the detection efficiency on the gain of the input stages of a detector is calculated and the result is applied to a MCP. Furthermore, an enhancement of the detection efficiency of a MCP is presented for 100 keV electrons up to more than 90% by means of the field-enhanced secondary electron emission. (author)

  17. Comparison of optimal performance at 300 keV of three direct electron detectors for use in low dose electron microscopy

    International Nuclear Information System (INIS)

    McMullan, G.; Faruqi, A.R.; Clare, D.; Henderson, R.

    2014-01-01

    Low dose electron imaging applications such as electron cryo-microscopy are now benefitting from the improved performance and flexibility of recently introduced electron imaging detectors in which electrons are directly incident on backthinned CMOS sensors. There are currently three commercially available detectors of this type: the Direct Electron DE-20, the FEI Falcon II and the Gatan K2 Summit. These have different characteristics and so it is important to compare their imaging properties carefully with a view to optimise how each is used. Results at 300 keV for both the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are presented. Of these, the DQE is the most important in the study of radiation sensitive samples where detector performance is crucial. We find that all three detectors have a better DQE than film. The K2 Summit has the best DQE at low spatial frequencies but with increasing spatial frequency its DQE falls below that of the Falcon II. - Highlights: • Three direct electron detectors offer better DQE than film at 300 keV. • Recorded 300 keV electron events on the detectors have very similar Landau distributions. • The Gatan K2 Summit detector has the highest DQE at low spatial frequency. • The FEI Falcon II detector has the highest DQE beyond one half the Nyquist frequency. • The Direct Electron DE-20 detector has the fastest data acquisition rate

  18. Comparison of optimal performance at 300 keV of three direct electron detectors for use in low dose electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    McMullan, G., E-mail: gm2@mrc-lmb.cam.ac.uk [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom); Faruqi, A.R. [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom); Clare, D. [Crystallography and Institute of Structural and Molecular Biology, Birkbeck College, University of London, Malet Street, London WC1E 7HX (United Kingdom); Henderson, R. [MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH (United Kingdom)

    2014-12-15

    Low dose electron imaging applications such as electron cryo-microscopy are now benefitting from the improved performance and flexibility of recently introduced electron imaging detectors in which electrons are directly incident on backthinned CMOS sensors. There are currently three commercially available detectors of this type: the Direct Electron DE-20, the FEI Falcon II and the Gatan K2 Summit. These have different characteristics and so it is important to compare their imaging properties carefully with a view to optimise how each is used. Results at 300 keV for both the modulation transfer function (MTF) and the detective quantum efficiency (DQE) are presented. Of these, the DQE is the most important in the study of radiation sensitive samples where detector performance is crucial. We find that all three detectors have a better DQE than film. The K2 Summit has the best DQE at low spatial frequencies but with increasing spatial frequency its DQE falls below that of the Falcon II. - Highlights: • Three direct electron detectors offer better DQE than film at 300 keV. • Recorded 300 keV electron events on the detectors have very similar Landau distributions. • The Gatan K2 Summit detector has the highest DQE at low spatial frequency. • The FEI Falcon II detector has the highest DQE beyond one half the Nyquist frequency. • The Direct Electron DE-20 detector has the fastest data acquisition rate.

  19. Deviation from an inverse cosine dependence of kinetic secondary electron emission for angle of incidence at keV energy

    International Nuclear Information System (INIS)

    Ohya, Kaoru; Kawata, Jun; Mori, Ichiro

    1989-01-01

    Incident angle dependence of kinetic secondary electron emission from metals resulting from incidence of keV ions is investigated by computer simulation with the TRIM Monte Carlo program of ion scattering in matter. The results show large deviations from the inverse cosine dependence, which derives from high-energy approximation, because of a series of elastic collisions of incident ions with metal atoms. In the keV energy region, the elastic collisions have two different effects on the angular dependence for relatively high-energy light ions and for low-energy heavy ions: they result in over- and under-inverse-cosine dependences, respectively. The properties are observed even with an experiment of the keV-neutral incidence on a contaminated surface. In addition, the effects of the thin oxide layer and roughness on the surface are examined with simplified models. (author)

  20. Analysis of the Air Cooling for 350 keV/20 mA Electron Beam Machine Rooms

    International Nuclear Information System (INIS)

    Sutadi; Suprapto; Suyamto; Sukaryono

    2003-01-01

    It has been analyzed the cooling capacity for 350 keV/20 mA electron beam machine rooms at P3TM. The analysis of cooling load based on the building construction and the device for supported the electron beam machines operation, were obtained head dissipation and provided the cooling load. From the result it can be determined that for cooling the electron beam machine rooms with 945 m cubic of volume and supporter device in the room, in order to reach the air condition about 20 o C of temperatures and 50 % of relative humidity for the electron beam machine rooms, it was needed the air conditioning system with total cooling capacity about 213.000 BTU/Hours. (author)

  1. Characteristics of pitch angle distributions of hundreds of keV electrons in the slot region and inner radiation belt

    Science.gov (United States)

    Zhao, H.; Li, X.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Baker, D. N.; Jaynes, A. N.; Malaspina, D. M.

    2014-12-01

    The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-the-art pitch angle-resolved data from the Magnetic Electron Ion Spectrometer instrument onboard the Van Allen Probes, a detailed analysis of hundreds of keV electron PADs below L = 4 is performed, in which the PADs are categorized into three types: normal (flux peaking at 90°), cap (exceedingly peaking narrowly around 90°), and 90° minimum (lower flux at 90°) PADs. By examining the characteristics of the PADs of ˜460 keV electrons for over a year, we find that the 90° minimum PADs are generally present in the inner belt (Lpitch angle scattering of hiss waves. Fitting the normal PADs into sinnα form, the parameter n is much higher below L = 3 than that in the outer belt and relatively constant in the inner belt but changes significantly in the slot region (2 mechanism can hardly explain the formation of 90° minimum PADs at the center of inner belt.

  2. Measurements of Relativistic Effects in Collective Thomson Scattering at Electron Temperatures less than 1 keV

    Energy Technology Data Exchange (ETDEWEB)

    Ross, James Steven [Univ. of California, San Diego, CA (United States)

    2010-01-01

    Simultaneous scattering from electron-plasma waves and ion-acoustic waves is used to measure local laser-produced plasma parameters with high spatiotemporal resolution including electron temperature and density, average charge state, plasma flow velocity, and ion temperature. In addition, the first measurements of relativistic modifications in the collective Thomson scattering spectrum from thermal electron-plasma fluctuations are presented [1]. Due to the high phase velocity of electron-plasma fluctuations, relativistic effects are important even at low electron temperatures (Te < 1 keV). These effects have been observed experimentally and agree well with a relativistic treatment of the Thomson scattering form factor [2]. The results are important for the interpretation of scattering measurements from laser produced plasmas. Thomson scattering measurements are used to characterize the hydrodynamics of a gas jet plasma which is the foundation for a broad series of laser-plasma interaction studies [3, 4, 5, 6]. The temporal evolution of the electron temperature, density and ion temperature are measured. The measured electron density evolution shows excellent agreement with a simple adiabatic expansion model. The effects of high temperatures on coupling to hohlraum targets is discussed [7]. A peak electron temperature of 12 keV at a density of 4.7 × 1020cm-3 are measured 200 μm outside the laser entrance hole using a two-color Thomson scattering method we developed in gas jet plasmas [8]. These measurements are used to assess laser-plasma interactions that reduce laser hohlraum coupling and can significantly reduce the hohlraum radiation temperature.

  3. 500 keV, 10 kW DC electron accelerator at BRIT, Vashi

    International Nuclear Information System (INIS)

    Sharma, D.K.; Rajan, R.N.; Bakhtsingh, R.I.; Acharya, S.; Rajawat, R.K.

    2017-01-01

    The 500 keV DC accelerator was indigenously designed and developed by Accelerator and Pulse Power Division, BARC during 1994-97 and commissioned at REPF Hall, BRIT, Vashi on 10"t"h August, 1998. The accelerator operation at 3kW beam power for 8 hour shifts was established in February 2001, confirming to industrial standards for EB treatment of plastic sheets as well as various surface-treatment processes for value addition of the products and materials. Since then, this EB facility is functional and being regularly utilized for various applications

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

    DEFF Research Database (Denmark)

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

    2009-01-01

    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...

  5. Modifications resulting in significant increases in the beam usage time of a 60 keV electron beam welder

    International Nuclear Information System (INIS)

    Zielinski, R.E.; Harrison, J.L.

    1976-01-01

    Short beam usage times were encountered using a 60 keV electron beam welder. These short times were the direct result of a buildup of a reaction product (WO 2 . 90 ) that occurred on graphite washers which housed the tungsten emitter plate. While it was not possible to prevent the reaction product, its growth rate was sufficiently altered by changing graphite materials and minor design changes of the washers. With these modifications beam usage times increased from an original 40 min to approximately 675 min

  6. Design of an accelerator tube for 500 keV/10 mA electron beam machine

    International Nuclear Information System (INIS)

    Maksum, W.; Sudjatmoko; Suprapto

    1999-01-01

    A design of an accelerator tube for 500 keV/10 mA electron beam machine was carried out. This tube was used for focussing and accelerating of electron beams. The tube was designed to consist of some electrodes insulator tubes and a voltage divider. The electrodes was made of stainless steel due to its low outgassing constant and stainless, the insulator was made of pyrex glass due to its low outgassing constant and high temperature proof and the voltage divider was made of high-ohmic resistors used for accelerating potential distribution at the electrodes. The stainless steel electrodes were comic shaped 3 mm thick with 134 mm inlet diameter and 60 mm outlet diameter. The number for this electrodes was 34 so that the potential gap between adjacent electrodes not exceed 15 kV. The insulators were 5 mm thick, 150 mm outer diameter, 140 mm inner diameter and 32 mm long. The insulators were joined to the electrodes by using an epoxy form an accelerator tube. The designed accelerator tube could be constructed and operated at a vacuum of 10 -6 torr and accelerated electron beam at an energy of 500 keV. (author)

  7. Echo 2: observations at Fort Churchill of a 4-keV peak in low-level electron precipitation

    International Nuclear Information System (INIS)

    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 assoicated 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

  8. 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...

  9. Investigation of chemical vapour deposition diamond detectors by X-ray micro-beam induced current and X-ray micro-beam induced luminescence techniques

    International Nuclear Information System (INIS)

    Olivero, P.; Manfredotti, C.; Vittone, E.; Fizzotti, F.; Paolini, C.; Lo Giudice, A.; Barrett, R.; Tucoulou, R.

    2004-01-01

    Tracking detectors have become an important ingredient in high-energy physics experiments. In order to survive the harsh detection environment of the large hadron collider (LHC), trackers need to have special properties. They must be radiation hard, provide fast collection of charge, be as thin as possible and remove heat from readout electronics. The unique properties of diamond allow it to fulfill these requirements. In this work we present an investigation of the charge transport and luminescence properties of 'detector grade' artificial chemical vapour deposition (CVD) diamond devices developed within the CERN RD42 collaboration, performed by means of X-ray micro-beam induced current collection (XBICC) and X-ray micro-beam induced luminescence (XBIL) techniques. XBICC technique allows quantitative estimates of the transport parameters of the material to be evaluated and mapped with micrometric spatial resolution. In particular, the high resolution and sensitivity of the technique has allowed a quantitative study of the inhomogeneity of the charge transport parameter defined as the product of mobility and lifetime for both electron and holes. XBIL represents a technique complementary to ion beam induced luminescence (IBIL), which has already been used by our group, since X-ray energy loss profile in the material is different from that of MeV ions. X-ray induced luminescence maps have been performed simultaneously with induced photocurrent maps, to correlate charge transport and induced luminescence properties of diamond. Simultaneous XBICC and XBIL maps exhibit features of partial complementarity that have been interpreted on the basis of considerations on radiative and non-radiative recombination processes which compete with charge transport efficiency

  10. Synchrotron X-ray micro-beam studies of ancient Egyptian make-up

    International Nuclear Information System (INIS)

    Martinetto, P.; Anne, M.; Dooryhee, E.; Drakopoulos, M.; Dubus, M.; Salomon, J.; Simionovici, A.; Walter, Ph.

    2001-01-01

    Vases full of make-up are most often present in the burial furniture of Egyptian tombs dated from the pharaonic period. The powdered cosmetics made of isolated grains are analysed to identify their trace element signature. From this signature we identify the provenance of the mineral ingredients in the make-up and we observe different impurities in products, which have been demonstrated as synthetic substances by previous works. Focused X-ray micro-beam (2x5 μm 2 ) is successively tuned at 11 keV, below the L III absorption edge of Pb, and 31.8 keV for global characterisation of the metal impurities. The fluorescence signal integrated over each single grain is detected against the X-ray micro-diffraction pattern collected in transmission with a bi-dimensional detector. Furthermore, for galena grains rich in Zn, the XANES signal at the K-absorption edge of Zn shows its immediate nearest-neighbour environment

  11. Synchrotron X-ray micro-beam studies of ancient Egyptian make-up

    Science.gov (United States)

    Martinetto, P.; Anne, M.; Dooryhée, E.; Drakopoulos, M.; Dubus, M.; Salomon, J.; Simionovici, A.; Walter, Ph.

    2001-07-01

    Vases full of make-up are most often present in the burial furniture of Egyptian tombs dated from the pharaonic period. The powdered cosmetics made of isolated grains are analysed to identify their trace element signature. From this signature we identify the provenance of the mineral ingredients in the make-up and we observe different impurities in products, which have been demonstrated as synthetic substances by previous works. Focused X-ray micro-beam ( 2×5 μm2) is successively tuned at 11 keV, below the L III absorption edge of Pb, and 31.8 keV for global characterisation of the metal impurities. The fluorescence signal integrated over each single grain is detected against the X-ray micro-diffraction pattern collected in transmission with a bi-dimensional detector. Furthermore, for galena grains rich in Zn, the XANES signal at the K-absorption edge of Zn shows its immediate nearest-neighbour environment.

  12. Synchrotron X-ray micro-beam studies of ancient Egyptian make-up

    Energy Technology Data Exchange (ETDEWEB)

    Martinetto, P; Anne, M; Dooryhee, E; Drakopoulos, M; Dubus, M; Salomon, J; Simionovici, A; Walter, Ph

    2001-07-01

    Vases full of make-up are most often present in the burial furniture of Egyptian tombs dated from the pharaonic period. The powdered cosmetics made of isolated grains are analysed to identify their trace element signature. From this signature we identify the provenance of the mineral ingredients in the make-up and we observe different impurities in products, which have been demonstrated as synthetic substances by previous works. Focused X-ray micro-beam (2x5 {mu}m{sup 2}) is successively tuned at 11 keV, below the L{sub III} absorption edge of Pb, and 31.8 keV for global characterisation of the metal impurities. The fluorescence signal integrated over each single grain is detected against the X-ray micro-diffraction pattern collected in transmission with a bi-dimensional detector. Furthermore, for galena grains rich in Zn, the XANES signal at the K-absorption edge of Zn shows its immediate nearest-neighbour environment.

  13. Signal yields of keV electronic recoils and their discrimination from nuclear recoils in liquid xenon

    Science.gov (United States)

    Aprile, E.; Aalbers, J.; Agostini, F.; Alfonsi, M.; Amaro, F. D.; Anthony, M.; Arneodo, F.; Barrow, P.; Baudis, L.; Bauermeister, B.; Benabderrahmane, M. L.; Berger, T.; Breur, P. A.; Brown, A.; Brown, E.; Bruenner, S.; Bruno, G.; Budnik, R.; Bütikofer, L.; Calvén, J.; Cardoso, J. M. R.; Cervantes, M.; Cichon, D.; Coderre, D.; Colijn, A. P.; Conrad, J.; Cussonneau, J. P.; Decowski, M. P.; de Perio, P.; di Gangi, P.; di Giovanni, A.; Diglio, S.; Eurin, G.; Fei, J.; Ferella, A. D.; Fieguth, A.; Fulgione, W.; Gallo Rosso, A.; Galloway, M.; Gao, F.; Garbini, M.; Geis, C.; Goetzke, L. W.; Grandi, L.; Greene, Z.; Grignon, C.; Hasterok, C.; Hogenbirk, E.; Howlett, J.; Itay, R.; Kaminsky, B.; Kazama, S.; Kessler, G.; Kish, A.; Landsman, H.; Lang, R. F.; Lellouch, D.; Levinson, L.; Lin, Q.; Lindemann, S.; Lindner, M.; Lombardi, F.; Lopes, J. A. M.; Mahlstedt, J.; Manfredini, A.; Maris, I.; Marrodán Undagoitia, T.; Masbou, J.; Massoli, F. V.; Masson, D.; Mayani, D.; Messina, M.; Micheneau, K.; Molinario, A.; Morâ, K.; Murra, M.; Naganoma, J.; Ni, K.; Oberlack, U.; Pakarha, P.; Pelssers, B.; Persiani, R.; Piastra, F.; Pienaar, J.; Pizzella, V.; Piro, M.-C.; Plante, G.; Priel, N.; Ramírez García, D.; Rauch, L.; Reichard, S.; Reuter, C.; Rizzo, A.; Rupp, N.; Saldanha, R.; Dos Santos, J. M. F.; Sartorelli, G.; Scheibelhut, M.; Schindler, S.; Schreiner, J.; Schumann, M.; Scotto Lavina, L.; Selvi, M.; Shagin, P.; Shockley, E.; Silva, M.; Simgen, H.; Sivers, M. V.; Stein, A.; Thers, D.; Tiseni, A.; Trinchero, G.; Tunnell, C.; Vargas, M.; Wang, H.; Wang, Z.; Wei, Y.; Weinheimer, C.; Wittweg, C.; Wulf, J.; Ye, J.; Zhang, Y.; Zhu, T.; Xenon Collaboration

    2018-05-01

    We report on the response of liquid xenon to low energy electronic recoils below 15 keV from beta decays of tritium at drift fields of 92 V /cm , 154 V /cm and 366 V /cm using the XENON100 detector. A data-to-simulation fitting method based on Markov Chain Monte Carlo is used to extract the photon yields and recombination fluctuations from the experimental data. The photon yields measured at the two lower fields are in agreement with those from literature; additional measurements at a higher field of 366 V /cm are presented. The electronic and nuclear recoil discrimination as well as its dependence on the drift field and photon detection efficiency are investigated at these low energies. The results provide new measurements in the energy region of interest for dark matter searches using liquid xenon.

  14. Angular distributions of projectiles following electron capture from C60 by 2.5-keV Ar8+

    International Nuclear Information System (INIS)

    Walch, B.; Thumm, U.; Stoeckli, M.; Cocke, C.L.; Klawikowski, S.

    1998-01-01

    Experimental measurements of the projectile angular distributions for 2.5-keV Ar 8+ ions capturing one to five electrons from a gas-phase C 60 target are presented. The number of captured electrons was determined by demanding a coincidence between the scattered projectile and a charge-state-analyzed intact C 60 recoil ion. The results are compared to calculations based on a dynamical classical overbarrier model. Good agreement is obtained only if the influence on the projectile trajectory by the large polarizability of the C 60 target is taken into account, thereby making the collective dielectric response of the cluster target observable in a scattering experiment. copyright 1998 The American Physical Society

  15. 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...... of the de Broglie wavelength lambda(dB) = 150 fm at a velocity v = 0.20 au and the effective atomic diameter for electron capture 2R = 20 au. Parallel AO and MO semiclassical coupled-channel calculations of the Na(3s, 3p) --> Li(2s, 2p) state-to-state collision amplitudes have been performed, and quantum...

  16. Method of transport simulation for electrons between 10eV and 30keV

    International Nuclear Information System (INIS)

    Terrissol, Michel.

    1978-01-01

    A transport simulation of low energy electrons in matter using a Monte-Carlo method and studying all the interactions of the electrons with atoms, molecules or assembly of them is described. Elastic scattering, ionization, excitation, plasmon creation, reorganization following inner-shell ionization, electron-hole pair creation ... are simulated individually by sampling of confirmed experimental or theoretical cross sections. So atomic and molecular gases, metals such as aluminium and liquid water have been studied. The simulation allows to follow the electrons until their energy reaches the atomic or molecular ionization potential of the irradiated matter. The entire trajectories of primary electron and of all secondaries set in motion are exactly reproduced. Several applications to multiple scattering, radiobiology, microdosimetry, electronic microscope are represented and some results are directly compared with experimental ones [fr

  17. Single impacts of keV fullerene ions on free standing graphene: Emission of ions and electrons from confined volume

    Energy Technology Data Exchange (ETDEWEB)

    Verkhoturov, Stanislav V.; Geng, Sheng; Schweikert, Emile A., E-mail: schweikert@chem.tamu.edu [Department of Chemistry, Texas A& M University, College Station, Texas 77843-3144 (United States); Czerwinski, Bartlomiej [Institute of Condensed Matter and Nanosciences–Bio and Soft Matter (IMCN/BSMA), Université Catholique de Louvain, 1 Croix du Sud, B-1348 Louvain-la-Neuve (Belgium); Applied Physics, Division of Materials Science, Department of Engineering Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå (Sweden); Young, Amanda E. [Materials Characterization Facility, Texas A& M University, College Station, Texas 77843-3122 (United States); Delcorte, Arnaud [Institute of Condensed Matter and Nanosciences–Bio and Soft Matter (IMCN/BSMA), Université Catholique de Louvain, 1 Croix du Sud, B-1348 Louvain-la-Neuve (Belgium)

    2015-10-28

    We present the first data from individual C{sub 60} impacting one to four layer graphene at 25 and 50 keV. Negative secondary ions and electrons emitted in transmission were recorded separately from each impact. The yields for C{sub n}{sup −} clusters are above 10% for n ≤ 4, they oscillate with electron affinities and decrease exponentially with n. The result can be explained with the aid of MD simulation as a post-collision process where sufficient vibrational energy is accumulated around the rim of the impact hole for sputtering of carbon clusters. The ionization probability can be estimated by comparing experimental yields of C{sub n}{sup −} with those of C{sub n}{sup 0} from MD simulation, where it increases exponentially with n. The ionization probability can be approximated with ejecta from a thermally excited (3700 K) rim damped by cluster fragmentation and electron detachment. The experimental electron probability distributions are Poisson-like. On average, three electrons of thermal energies are emitted per impact. The thermal excitation model invoked for C{sub n}{sup −} emission can also explain the emission of electrons. The interaction of C{sub 60} with graphene is fundamentally different from impacts on 3D targets. A key characteristic is the high degree of ionization of the ejecta.

  18. Evolution of substorm and quiet-time electron anisotropies (30 less than or equal to E/sub e/ less than or equal to 300 keV)

    International Nuclear Information System (INIS)

    Higbie, P.R.; Baker, D.N.; Belian, R.D.; Hones, E.W. Jr.

    1979-01-01

    Work using the Charged Particle Analyzer (CPA) instruments aboard spacecraft 1976-059A and 1977-007A in synchronous orbit has shown that approx. 30 keV electron anisotropies may act as a sensitive indicator of the buildup of stresses in the outer magnetosphere. The development of such stresses is evidenced in the premidnight sector by the formation of field-aligned (cigar) anisotropies in the 30 keV electrons one to two hours prior to the onset of the expansion phase of the substorm. Using the complete three-dimensional pitch angle measurement capability of the CPA, it is shown in a movie format the detailed development of electron anisotropies during the course of substorm growth, expansion, and recovery phases. In contrast, detailed examples of quiet-time behavior of electron anisotropies at several energy levels between 30 and 300 keV are also shown. Such periods with no substorm activity show that 30 keV electrons remain approx. isotropic (outside the loss cone) throughout the nighttime sector, even though the higher energy (> 100 keV) electrons show the development of cigar anisotropies associated with normal drift-shell splitting. These results emphasize the substorm predictive capabilities of the low energy electron anisotropies and illustrate how the data might be used in a real-time monitoring mode. 19 references

  19. Modeling the process of interaction of 10 keV electrons with a plane dielectric surface

    Science.gov (United States)

    Vokhmyanina, Kristina; Sotnikova, Valentina; Sotnikov, Alexey; Kaplii, Anna; Nikulicheva, Tatyana; Kubankin, Alexandr; Kishin, Ivan

    2018-05-01

    The effect of guiding of charged particles by dielectric channels is of noticeable interest at the present time. The phenomenon is widely studied experimentally and theoretically but some points still need to be clarified. A previously developed model of interaction of fast electrons with dielectric surface at grazing incidence is used to study the independence of electron deflection on the value of electron beam current. The calculations were performed assuming a smooth dependence of the surface conductivity on the beam current in the 40-3000 nA range.

  20. Effect of initial-state target polarization on the single ionization of helium by 1-keV electron impact

    International Nuclear Information System (INIS)

    Sun Shi-Yan; Ma Xiao-Yan; Li Xia; Miao Xiang-Yang; Jia Xiang-Fu

    2012-01-01

    We report new results of triple differential cross sections for the single ionization of helium by 1-KeV electron impact at the ejection energy of 10 eV. Investigations have been made for both the perpendicular plane and the plane perpendicular to the momentum transfer geometries. The present calculation is based on the three-Coulomb wave function. Here we have also incorporated the effect of target polarization in the initial state. A comparison is made between the present calculation with the results of other theoretical methods and a recent experiment [Dürr M, Dimopoulou C, Najjari B, Dorn A, Bartschat K, Bray I, Fursa D V, Chen Z, Madison D H and Ullrich J 2008 Phys. Rev. A 77 032717]. At an impact energy of 1 KeV, the target polarization is found to induce a substantial change of the cross section for the ionization process. We observe that the effect of target polarization plays a dominant role in deciding the shape of triple differential cross sections. (atomic and molecular physics)

  1. Absolute cross section measurement for the ionization of the K-shell of titanium and nickel by electron impact (50 KEV)

    International Nuclear Information System (INIS)

    Jessenberger, J.

    1974-01-01

    The yield of characteristic X-ray K radiation of titanium during bombardment with electrons in the energy region of 6-50 keV and of nickel at 9-50 keV was measured, and the cross sections for th ionization of the K shell of titanium and nickel were determined from this. The results obtained are compared with several theoretical models. (WL/LN) [de

  2. Characterisation of a monolithic active pixel sensor for electron detection in the energy range 10-20 keV

    International Nuclear Information System (INIS)

    Matheson, J.; Moldovan, G.; Clark, A.; Prydderch, M.; Turchetta, R.; Derbyshire, G.; Kirkland, A.; Allinson, N.

    2009-01-01

    As part of a feasibility study into the use of novel electron detectors for X-ray photoelectron emission microscopes (XPEEM), we have characterised the imaging performance of a back-illuminated monolithic active pixel sensor (MAPS) operating under both integrating and counting modes for electrons in the energy range 10-20 keV. For integrating mode, we present the detective quantum efficiency (DQE), which shows marked improvements over conventional indirect detectors based on microchannel plates. We also present the modulation transfer function (MTF) and noise power spectrum (NPS), again demonstrating significantly improved performance. For counting mode, we present the quantum efficiency (QE) as a function of incident electron energy. We have evaluated the charge collection efficiency (CCE) and we thereby demonstrate the presence of a ∼200 nm thick dead layer that is linked with reduced CCE at low electron energies. Based on our findings, we believe that the MAPS technology is well matched to future XPEEM instruments using aberration correction.

  3. 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.

  4. Double capture in the O8+ + He collision investigated by electron spectroscopy (80 keV, 10 deg)

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Benoit-Cattin, P.; Bordenave-Montesquieu, A.; Boudjema, M.; Gleizes, A.; Dousson, S.; Hitz, D.

    1989-01-01

    Double capture into (3,n) autoionising states of O 6+ is observed in the O 8+ + He collision system by electron spectroscopy at 80 keV, 10 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 7+ + He and Ne 8+ (1s 2 ) + He systems. The influence of the core of the multicharged ion is studied by examining the O 8+ and Ne 8+ (1s 2 ) results. The total double capture cross section is found to be large and it is compared with available experimental and theoretical data. (author)

  5. 40 keV Shaped electron beam lithography for LIGA intermediate mask fabrication

    NARCIS (Netherlands)

    Luttge, R.; Adam, D.; Burkhardt, F.; Hoke, F.; Schacke, H.; Schmidt, M.; Wolf, H.; Schmidt, A.

    1999-01-01

    High precision LIGA masks require a soft X-ray pattern transfer from intermediate masks by means of electron beam lithography. Such a process has been realized using an upgraded Leica ZBA 23 machine with an acceleration voltage of 40 kV. Three process variations of the developer system, so called GG

  6. Subshell resolved L shell ionization of Bi and U induced by 16 - 45 keV electrons

    International Nuclear Information System (INIS)

    Rahangdale, Hitesh; Das, Pradipta K.; Saha, S.; Mitra, D.

    2015-01-01

    Electron induced inner-shell ionization is important for both fundamental and applied research. Ionization of outer atomic energy levels has been studied extensively than for inner levels. Knowledge of inner shell ionization cross sections is important in X-ray and Auger electron spectroscopy and in the fields of astrophysics, plasma physics, surface science and many more. At electron impact energies near the atomic binding energies the distortion of the wave functions from plane wave towards a spherical wave, due to the electrostatic field of the atoms, needs to be considered. The distorted wave Born approximation (DWBA) calculations, taking relativistic effects and exchange interaction into account, is used to estimate the K, L and M-shell ionization cross-section for the atoms. Earlier experiments on electron impact ionization studies focused mainly on K-shell ionization cross-section, while L and M-shell ionization data were hardly reported. A review of the existing L-shell ionization cross-section data shows that, while the X-ray production cross-sections by electron impact were reported quite a few times, the reporting of subshell resolved ionization cross-sections were rarely found near the ionization threshold region. In the present work, we have measured the X ray production cross-sections of different L lines of Bi and U induced by 16-45 keV electrons and converted the obtained values to the subshell specific ionization cross-sections. The experimental data are compared with the theoretical calculations based on the (DWBA) obtained from PENELOPE. To the best of our knowledge, the subshell resolved electron induced ionization cross-sections for the L-shell of Bi and U are reported here for the first time at the energy values near the corresponding ionization threshold. (author)

  7. Studies on the bombardment of condensed molecular gases at liquid-He temperatures by keV electrons and light ions

    International Nuclear Information System (INIS)

    Boergesen, P.

    1982-09-01

    Films of solid H 2 , D 2 and N 2 were irradiated with keV electrons and ions. Stopping cross sections and ranges of 0.3-10 keV/amu light ions in solid H 2 and D 2 are in good agreement with experimental and theoretical data on gaseous targets. In contrast, both stopping cross section and range measurements in solid N 2 suggest that the stopping here is only about half of that in N 2 -gas. This ''phase-effect'' is further supported by secondary emission measurements. Secondary electron emission coefficients for 2-10 keV H 1 + , H 2 + , H 3 + , D 3 + , D 2 H + , 4 He + , 14 N + and 20 Ne + incident on solids H 2 , D 2 and N 2 are in reasonable agreement with previous results for electron-incidence. The rather large erosion yields for 1-3 keV electrons incident on solid D 2 depend strongly on target thickness (for thin films), but weakly on energy. Bulk yields for 2 keV electrons were approximately 8 H 2 /electron, approximately 4 D 2 /electron and approximately 0.5 N 2 /electron. Secondary ion emission during ion bombardment seems to be predominantly reflected projectiles in the case of N 2 -targets, while it may be explained as sputtered particles from H 2 - and D 2 -targets. Preliminary results on the erosion of solid H 2 and D 2 by keV light ions indicate very large erosion yields (approx. 400 H 2 /atom for 2 keV protons) increasing strongly with energy. (Auth.)

  8. 200 keV electron beam pulse source for the complex VEPP-5 preinjector

    CERN Document Server

    Akimov, V E; Korepanov, A A

    2001-01-01

    The electron beam source based on GS-34 valve cathode-grid unit with oxide cathode of 12 mm in diameter is described. Originally the high voltage DC source was used to supply the gun. The cathode emission characteristic was reduced by the vacuum breakdowns during gun operation. So the necessity of decreasing a high voltage from 200 kV to 140 kV has appeared. The use of the pulse transformer based gun supply with a pulse duration of approx 1 mcs provided the gun operation without breakdowns at a voltage of 200 kV and pulse repetition rate up to 50 Hz. At present time the electron source is operated at the complex VEPP-5 preinjector.

  9. Effects of 500 keV electron irradiation and subsequent annealing on 1/f noise in copper films

    International Nuclear Information System (INIS)

    Pelz, J.; Clarke, J.

    1985-10-01

    Polycrystalline copper films were maintained at 90K on the cold stage of an electron microscope and irradiated with 500keV electrons to induce defect. With an electron dose of about 5 x 10 20 cm -2 , the spectral density of the noise voltage across the films increased by an order of magnitude while the electrical resistivity increased by at most 10%. The films were annealed at progressively higher temperatures; after each annealing process the 1/f noise and resistivity were remeasured at 90K. Both the 1/f noise and resistivity were reduced, but at the lower annealing temperatures the fractional reduction in the added noise was substantially more than in the added resistivity. These result suggest that a large fraction of the added noise may be generated by a small mobile fraction of the added defects that are more readily annealed than the majority of the defects. After a room temperature annealing process, both the noise and resistivity returned nearly to their initial values. The temperature dependence of the noise after irradiation and partial annealing was consistant with the Dutta-Dimon-Horn thermal activation model

  10. A DATABASE OF >20 keV ELECTRON GREEN'S FUNCTIONS OF INTERPLANETARY TRANSPORT AT 1 AU

    Energy Technology Data Exchange (ETDEWEB)

    Agueda, N.; Sanahuja, B. [Departament d' Astronomia i Meteorologia, Institut de Ciencies del Cosmos, Universitat de Barcelona, Barcelona (Spain); Vainio, R. [Department of Physics, University of Helsinki, Helsinki (Finland)

    2012-10-15

    We use interplanetary transport simulations to compute a database of electron Green's functions, i.e., differential intensities resulting at the spacecraft position from an impulsive injection of energetic (>20 keV) electrons close to the Sun, for a large number of values of two standard interplanetary transport parameters: the scattering mean free path and the solar wind speed. The nominal energy channels of the ACE, STEREO, and Wind spacecraft have been used in the interplanetary transport simulations to conceive a unique tool for the study of near-relativistic electron events observed at 1 AU. In this paper, we quantify the characteristic times of the Green's functions (onset and peak time, rise and decay phase duration) as a function of the interplanetary transport conditions. We use the database to calculate the FWHM of the pitch-angle distributions at different times of the event and under different scattering conditions. This allows us to provide a first quantitative result that can be compared with observations, and to assess the validity of the frequently used term beam-like pitch-angle distribution.

  11. Compact Source of Electron Beam with Energy of 200 kEv and Average Power of 2 kW

    CERN Document Server

    Kazarezov, Ivan; Balakin, Vladimir E; Bryazgin, Alex; Bulatov, Alexandre; Glazkov, Ivan; Kokin, Evgeny; Krainov, Gennady; Kuznetsov, Gennady I; Molokoedov, Andrey; Tuvik, Alfred

    2005-01-01

    The paper describes a compact electron beam source with average electron energy of 200 keV. The source operates with pulse power up to 2 MW under average power not higher than 2 kW, pulsed beam current up to 10 A, pulse duration up to 2 mks, and repetition rate up to 5 kHz. The electron beam is extracted through aluminium-beryllium alloy foil. The pulse duration and repetition rate can be changed from control desk. High-voltage generator for the source with output voltage up to 220 kV is realized using the voltage-doubling circuit which consists of 30 sections. The insulation type - gas, SF6 under pressure of 8 atm. The cooling of the foil supporting tubes is provided by a water-alcohol mixture from an independent source. The beam output window dimensions are 180?75 mm, the energy spread in the beam +10/-30%, the source weight is 80 kg.

  12. The effects of 500 keV electron irradiation and subsequent annealing on 1/f noise in copper films

    International Nuclear Information System (INIS)

    Pelz, J.; Clarke, J.

    1986-01-01

    Polycrystalline copper films were maintained at 90K on the cold stage of an electron microscope and irradiated with 500keV electrons to induce defects. With an electron dose of about 5 x 10 20 cm -2 , the spectral density of the noise voltage across the films increased by an order of magnitude while the electrical resistivity increased by at most 10%. The films were annealed at progressively higher temperatures; after each annealing process the 1/f noise and resistivity were remeasured at 90K. Both the 1/f noise and resistivity were reduced, but at the lower annealing temperatures the fractional reduction in the added noise was substantially more than in the added resistivity. These results suggest that a large fraction of the added noise may be generated by a small mobile fraction of the added defects that are more readily annealed than the majority of the defects. After a room temperature annealing process, both the noise and resistivity returned nearly to their initial values. The temperature dependence of the noise after irradiation and partial annealing was consistent with the Dutta-Dimon-Horn thermal activation model. (Auth.)

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

    International Nuclear Information System (INIS)

    Poel, M van der; Nielsen, C V; Rybaltover, M; Nielsen, S E; Machholm, M; Andersen, N

    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. This setup yields a momentum resolution of 0.12 au, an order of magnitude better angular resolution than previous measurements on this system. This enables us to clearly resolve Fraunhofer-type diffraction patterns in the angle DCS. In particular, the angular width of the ring structure is given by the ratio of the de Broglie wavelength λ dB = 150 fm at a velocity v = 0.20 au and the effective atomic diameter for electron capture 2R = 20 au. Parallel AO and MO semiclassical coupled-channel calculations of the Na(3s, 3p) → Li(2s, 2p) state-to-state collision amplitudes have been performed, and quantum scattering amplitudes are derived by the eikonal method. The resulting angle-differential electron transfer cross sections and their diffraction patterns agree with the experimental level-to-level results over most scattering angles in the energy range

  14. Hard x-ray (>100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the NIF.

    Science.gov (United States)

    Döppner, T; Dewald, E L; Divol, L; Thomas, C A; Burns, S; Celliers, P M; Izumi, N; Kline, J L; LaCaille, G; McNaney, J M; Prasad, R R; Robey, H F; Glenzer, S H; Landen, O L

    2012-10-01

    We have fielded a hard x-ray (>100 keV) imager with high aspect ratio pinholes to measure the spatially resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions and are a source of preheat to the deuterium-tritium fuel. First measurements show that hot electron preheat does not limit obtaining the fuel areal densities required for ignition and burn.

  15. Secondary Electron Emission from Solid Hydrogen and Deuterium Resulting from Incidence of keV Electrons and Hydrogen Ions

    DEFF Research Database (Denmark)

    Sørensen, H.

    1977-01-01

    are small, in contrast to what is expected for insulating materials. One explanation is that the secondary electrons lose energy inside the target material by exciting vibrational and rotational states of the molecules, so that the number of electrons that may escape as secondary electrons is rather small....... The losses to molecular states will be largest for hydrogen, so that the SEE coefficients are smallest for solid hydrogen, as was observed. For the incidence of ions, the values of δ for the different molecular ions agree when the number of secondary electrons per incident atom is plotted versus the velocity...... or the stopping power of the incident particles. Measurements were also made for oblique incidence of H+ ions on solid deuterium for angles of incidence up to 75°. A correction could be made for the emission of secondary ions by also measuring the current calorimetrically. At largest energies, the angular...

  16. On the morphology of energetic (>= 30 keV) electron precipitation at the onset of negative magnetic bays

    International Nuclear Information System (INIS)

    Pytte, T.; Trefall, H.; Kremser, G.; Tanskanen, P.; Riedler, W.

    1976-01-01

    Recordings of Bremsstrahlung X-rays supported by recordings of cosmic noise absorption have been used to study in detail energetic (>= 30 keV) electron precipitation events occurring near local midnight at the onset of the expansion phase of magnetospheric substorms. This type of precipitation occurs during the first 5 to 10 min after bay onset and can usually be distinguished from the subsequent bay-associated precipitation by its characteristic time structure, variation in energy spectrum, and higher intensities. During this same interval, the poleward border of the precipitation region moves rapidly towards higher latitudes with speeds of typically 1 to 2 km/s, whereas the equatorward border seems to move slowly towards lower latitudes. The northward expansion starts just poleward of the lowest latitudes reached during the slow equatorward motion of the preceding growth-phase precipitation. The previous narrow precipitation region may thus expand to as much as 10 0 of invariant latitude within a few minutes. Within the expanding region there are additional intrinsic temporal variations. As the flux of precipitating electrons tends to be most intense and most energetic near the poleward border, recordings made northward of the latitude where the poleward motion started tend to give the appearance of an impulsive precipiation event. The bay-onset precipiation starts abruptly at the onset of Pi 2 magnetic pulsations. Associated with these pulsations there are modulations of the flux of precipitating electrons. An intensified westward electrojet appears to have its center in the equatorward part of the precipitation region. The results are discussed and a mechanism is proposed. (author)

  17. XRAY applied program package for calculation of electron-photon fields in the energy range of 1-1000 keV

    International Nuclear Information System (INIS)

    Lappa, A.V.; Khadyeva, Z.M.; Burmistrov, D.S.; Vasil'ev, O.N.

    1990-01-01

    The package of applied XRAY programs is intended for calculating the linear and fluctuation characteristics of photon and electron radiation fields in heterogeneous medium within 1-1000 keV energy range. The XRAY program package consists of moduli written in FORTRAN-IV and data files. 9 refs

  18. New approach to K-electron-capture probabilities to the 437 and 384 keV levels in the decay of /sup 133/Ba

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

    1983-12-01

    The K-electron-capture probabilities to the 437 and 384 keV levels in the decay of /sup 133/Ba have been determined from a measurement of gamma-ray intensities in conjunction with an analysis of the K x-ray-gamma-ray sum peaks. The results are independent of fluorescence yield and detector efficiency.

  19. Cross sections for one-electron capture by highly stripped ions of Be, B and C from H2 and Ar below 10 keV

    International Nuclear Information System (INIS)

    Takagi, S.; Ohtani, S.; Kadota, K.; Fujita, J.

    1982-03-01

    Cross sections for one-electron capture by highly stripped ions of Be, B and C from H 2 and Ar are measured at low energies below 10 keV. The cross sections are nearly independent of the collision energy investigated. The distinct oscillation with incident ionic charge g in the cross sections are observed. (author)

  20. Analysis of strain error sources in micro-beam Laue diffraction

    International Nuclear Information System (INIS)

    Hofmann, Felix; Eve, Sophie; Belnoue, Jonathan; Micha, Jean-Sébastien; Korsunsky, Alexander M.

    2011-01-01

    Micro-beam Laue diffraction is an experimental method that allows the measurement of local lattice orientation and elastic strain within individual grains of engineering alloys, ceramics, and other polycrystalline materials. Unlike other analytical techniques, e.g. based on electron microscopy, it is not limited to surface characterisation or thin sections, but rather allows non-destructive measurements in the material bulk. This is of particular importance for in situ loading experiments where the mechanical response of a material volume (rather than just surface) is studied and it is vital that no perturbation/disturbance is introduced by the measurement technique. Whilst the technique allows lattice orientation to be determined to a high level of precision, accurate measurement of elastic strains and estimating the errors involved is a significant challenge. We propose a simulation-based approach to assess the elastic strain errors that arise from geometrical perturbations of the experimental setup. Using an empirical combination rule, the contributions of different geometrical uncertainties to the overall experimental strain error are estimated. This approach was applied to the micro-beam Laue diffraction setup at beamline BM32 at the European Synchrotron Radiation Facility (ESRF). Using a highly perfect germanium single crystal, the mechanical stability of the instrument was determined and hence the expected strain errors predicted. Comparison with the actual strain errors found in a silicon four-point beam bending test showed good agreement. The simulation-based error analysis approach makes it possible to understand the origins of the experimental strain errors and thus allows a directed improvement of the experimental geometry to maximise the benefit in terms of strain accuracy.

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

    International Nuclear Information System (INIS)

    Nogueira, J.C.

    1977-01-01

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

  2. Mean free paths by inelastic interactions, stopping powers, and energy straggling for electrons of energies up to 20 keV in various solids

    International Nuclear Information System (INIS)

    Akkerman, A.F.; Chernov, G.Ya.

    1978-01-01

    For the elements C, Be, Mg, Al, Si, K, Ge, Sb, Bi calculations of the mean free paths and stopping powers of low energy electrons are performed. In the computational model Lindhard's formalism of the dielectric response function for pair and plasmon excitation and the classical cross-section for ionization processes are used. Anomalously high mean free paths and small stopping powers in potassium are found. This behaviour which is connected with low electron concentration in the valence band is expected to hold for all alkali metals. For energies above 10 keV the calculated dE/dx agree well with values calculated from the Bethe-Bloch formula. A Monte-Carlo method is used for the calculation of the energy loss distribution of electrons passing through thin targets. It is noted that Blunck-Leisegang's theory fails to render the energy straggling at electron energies below 10 keV. (author)

  3. 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.

  4. Measurements of Lα, Lβ X-ray production cross sections of Bi by 17-40 keV electron impact

    International Nuclear Information System (INIS)

    Wu, Y.; An, Z.; Duan, Y.M.; Liu, M.T.

    2010-01-01

    We present results of measurements of L α , L β X-ray production cross sections for the element Bi (Z = 83) by 17-40 keV electron impact. The target used in the experiment was prepared by evaporating the element Bi to the thick pure carbon substrate. The effects of multiple scattering of electrons when penetrating the target film, of electrons reflected from the thick pure carbon substrate and of bremsstrahlung photons produced by the impact of incident electrons on the target are corrected by means of Monte Carlo simulation. The experimental data, reported here for the first time in the energy region of 17-40 keV, are compared with the DWBA theory and the PWBA-C-Ex theory. They are in good agreement.

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

    Science.gov (United States)

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

    2013-04-01

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

  6. Electron fluence to dose equivalent conversion factors calculated with EGS3 for electrons and positrons with energies from 100 keV to 20 GeV

    International Nuclear Information System (INIS)

    Rogers, D.W.O.

    1983-01-01

    At NRC the general purpose Monte-Carlo electron-photon transport code EGS3 is being applied to a variety of radiation dosimetry problems. To test its accuracy at low energies a detailed set of depth-dose curves for electrons and photons has been generated and compared to previous calculations. It was found that by changing the default step-size algorithm in EGS3, significant changes were obtained for incident electron beam cases. It was found that restricting the step-size to a 4% energy loss was appropriate below incident electron beam energies of 10 MeV. With this change, the calculated depth-dose curves were found to be in reasonable agreement with other calculations right down to incident electron energies of 100 keV although small (less than or equal to 10%) but persistent discrepancies with the NBS code ETRAN were obtained. EGS3 predicts higher initial dose and shorter range than ETRAN. These discrepancies are typical of a wide range of energies as is the better agreement with the results of Nahum. Data is presented for the electron fluence to maximal dose equivalent in a 30 cm thick slab of ICRU 4-element tissue irradiated by broad parallel beams of electrons incident normal to the surface. On their own, these values only give an indication of the dose equivalent expected from a spectrum of electrons since one needs to fold the spectrum maximal dose equivalent value. Calculations have also been done for incident positron beams. Despite the large statistical uncertainties, maximal dose equivalent although their values are 5 to 10% lower in a band around 10 MeV

  7. Effective atomic numbers and electron densities of some biologically important compounds containing H, C, N and O in the energy range 145-1330 keV

    International Nuclear Information System (INIS)

    Manjunathaguru, V; Umesh, T K

    2006-01-01

    A semi-empirical relation which can be used to determine the total attenuation cross sections of samples containing H, C, N and O in the energy range 145-1332 keV has been derived based on the total attenuation cross sections of several sugars, amino acids and fatty acids. The cross sections have been measured by performing transmission experiments in a narrow beam good geometry set-up by employing a high-resolution hyperpure germanium detector at seven energies of biological importance such as 145.4 keV, 279.2 keV, 514 keV, 661.6 keV, 1115.5 keV, 1173.2 keV and 1332.1 keV. The semi-empirical relation can reproduce the experimental values within 1-2%. The total attenuation cross sections of five elements carbon, aluminium, titanium, copper and zirconium measured in the same experimental set-up at the energies mentioned above have been used in a new matrix method to evaluate the effective atomic numbers and the effective electron densities of samples such as cholesterol, fatty acids, sugars and amino acids containing H, C, N and O atoms from their effective atomic cross sections. The effective atomic cross sections are the total attenuation cross sections divided by the total number of atoms of all types in a particular sample. Further, a quantity called the effective atomic weight was defined as the ratio of the molecular weight of a sample to the total number of atoms of all types in it. The variation of the effective atomic number was systematically studied with respect to the effective atomic weight and a new semi-empirical relation for Z eff has been evolved. It is felt that this relation can be very useful to determine the effective atomic number of any sample having H, C, N and O atoms in the energy range 145-1332 keV irrespective of its chemical structure

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

    Science.gov (United States)

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

    2011-02-07

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

  9. Study on electron fluxes with Esub(e)=40-500 keV in quiet periods of solar activity by means of correlation and spectral analysis technique

    International Nuclear Information System (INIS)

    Zel'dovich, M.A.; Trebukhovskaya, G.A.

    1982-01-01

    Background fluxes of low-energy electrons (Esub(e)=40-500 keV), observed in the interplanetary space in the absence of solar cosmic ray flares using the ''Prognoz-3'' artificial satellite during 1973-1974, are under study. Fluctuation power spectra and correlation functions of simultaneous series of fluxes of above electrons, galactic cosmic rays are calculated along with some parameters characterizing solar activity and interplanetary medium state. The mentioned analysis points to possible solar origin of background low-energy electron fluxes

  10. Measurement of the electronic absorption coefficient for 57Co 14.4 keV gamma photons in aluminium using the Moessbauer effect as a monochromator

    International Nuclear Information System (INIS)

    Rajan, N.; Nigam, A.K.

    1984-01-01

    The total electronic absorption coefficient for 14.4 keV gamma photons in aluminium, has been measured experimentally, for the first time, using the Moessbauer effect as a monochromator. This data is important for the determination of background in Moessbauer recoilless fraction measurements especially if the energy of X-rays of the source host lattice lie near the 14.4 keV photon energy (e.g. in Rh and Pd) in which case electronic absorption coefficients should be known precisely. The coefficient obtained by interpolation from available values at other energies differ from our experimental value by as much as 20%. It is shown that this can lead to errors, in recoilless fraction values, which are far from negligible. The above absorption coefficient for aluminium was measured to be 11+-1 cm 2 /g. (orig.)

  11. On the effective atomic number and electron density: A comprehensive set of formulas for all types of materials and energies above 1 keV

    DEFF Research Database (Denmark)

    Manohara, S.R.; Hanagodimath, S.M.; Thind, K.S.

    2008-01-01

    A comprehensive and consistent set of formulas is given for calculating the effective atomic number and electron density for all types of materials and for all photon energies greater than 1 keV. The are derived from first principles using photon interaction cross sections of the constituent atom....... The theory is illustrated by calculations and experiments for molecules of medical and biological interest, glasses for radiation shielding, alloys, minerals and liquids....

  12. A Combined Model of Charging of the Surface and Bulk of a Dielectric Target by Electrons with the Energies 10-30 keV

    Science.gov (United States)

    Zykov, V. M.; Neiman, D. A.

    2018-04-01

    A physico-mathematical model of the processes of radiation-induced charging of dielectric materials with open surfaces, irradiated with monoenergetic electrons in the energy range 10-30 keV, is described. The model takes into account the relationship between the processes of surface and bulk charging for the given conditions of the experimental design, which accounts for the effect of anomalously long charging of dielectrics after the incident energy of primary electrons during charging is reduced to below the second critical energy for the secondary electronic emission coefficient. The initial fast phase of charging a high-resistivity dielectric material (Al2O3) is investigated. It is shown that as the incident electron energy is approaching the second critical energy during charging, the secondary electronic emission is partially suppressed due to negative charging of the open surface of the dielectric and formation of a near-surface inversion electrical field retarding the electronic emission yield.

  13. Characterization and optimization of laser-driven electron and photon sources in keV and MeV energy ranges

    International Nuclear Information System (INIS)

    Bonnet, Thomas

    2013-01-01

    This work takes place in the framework of the characterization and the optimization of laser-driven electron and photon sources. With the goal of using these sources for nuclear physics experiments, we focused on 2 energy ranges: one around a few MeV and the other around a few tens of keV. The first part of this work is thus dedicated to the study of detectors routinely used for the characterization of laser-driven particle sources: Imaging Plates. A model has been developed and is fitted to experimental data. Response functions to electrons, photons, protons and alpha particles are established for SR, MS and TR Fuji Imaging Plates for energies ranging from a few keV to several MeV. The second part of this work present a study of ultrashort and intense electron and photon sources produced in the interaction of a laser with a solid or liquid target. An experiment was conducted at the ELFIE facility at LULI where beams of electrons and photons were accelerated up to several MeV. Energy and angular distributions of the electron and photons beams were characterized. The sources were optimized by varying the spatial extension of the plasma at both the front and the back end of the initial target position. In the optimal configuration of the laser-plasma coupling, more than 1011 electrons were accelerated. In the case of liquid target, a photon source was produced at a high repetition rate on an energy range of tens of keV by the interaction of the AURORE Laser at CELIA (10 16 W.cm -2 ) and a melted gallium target. It was shown that both the mean energy and the photon number can be increased by creating gallium jets at the surface of the liquid target with a pre-pulse. A physical interpretation supported by numerical simulations is proposed. (author)

  14. Origin of Si(LMM) Auger Electron Emission from Silicon and Si-Alloys by keV Ar+ Ion Bombardment

    Science.gov (United States)

    Iwami, Motohiro; Kim, Su Chol; Kataoka, Yoshihide; Imura, Takeshi; Hiraki, Akio; Fujimoto, Fuminori

    1980-09-01

    Si(LMM) Auger electrons emitted from specimens of pure silicon and several Si-alloys (Ni-Si, Pd-Si and Cu-Si) under keV Ar+ ion bombardment, were examined. In the Auger spectra from all specimens studied there were four peaks at energies of 92, 86, 76 and 66 eV. The Auger signal intensity varied considerably with both the incident angle and the energy of the primary ion beam. It is proposed that the Auger electrons are emitted from silicon atoms (or ions) just beneath the specimen surface but free from the bulk network.

  15. Origin of Si(LMM) Auger electron emission from silicon and Si-alloys by keV Ar/sup +/ ion bombardment

    Energy Technology Data Exchange (ETDEWEB)

    Iwami, M; Kim, S; Kataoka, Y; Imura, T; Hiraki, A [Osaka Univ., Suita (Japan). Faculty of Engineering

    1980-09-01

    Si(LMM) Auger electrons emitted from specimens of pure silicon and several Si-alloys (Ni-Si, Pd-Si and Cu-Si) under keV Ar/sup +/ ion bombardment, were examined. In the Auger spectra from all specimens studied there were four peaks at energies of 92, 86, 76 and 66 eV. The Auger signal intensity varied considerably with both the incident angle and the energy of the primary ion beam. It is proposed that the Auger electrons are emitted from silicon atoms (or ions) just beneath the specimen surface but free from the bulk network.

  16. Dipole term and first derivative at K=0 of the generalized oscillator strength of He by keV electron impact

    International Nuclear Information System (INIS)

    Backx, C.; Tol, R.R.; Wight, G.R.; Wiel, M.J. van der

    1975-01-01

    An approximate method is described for obtaining the derivative to K 2 of the generalized oscillator strength for keV electron scattering at zero momentum transfer, over a large range of energy losses. The measured data enable the reduction of the systematical uncertainty in the derivation of optical oscillator strengths to below 1%. Results are presented for He over the spectral range of 19 to 65 eV. The data for the derivation are in satisfactory agreement with earlier electron scattering results at lower impact energy and extend over a sufficient range to allow the application of a sum rule for this term of the generalized oscillator strength. (Auth.)

  17. Compton scattering study of electron momentum distribution in lithium fluoride using 662 keV gamma radiations

    Science.gov (United States)

    Vijayakumar, R.; Shivaramu; Ramamurthy, N.; Ford, M. J.

    2008-12-01

    Here we report the first ever 137Cs Compton spectroscopy study of lithium fluoride. The spherical average Compton profiles of lithium fluoride are deduced from Compton scattering measurements on poly crystalline sample at gamma ray energy of 662 keV. To compare the experimental data, we have computed the spherical average Compton profiles using self-consistent Hartree-Fock wave functions employed on linear combination of atomic orbital (HF-LCAO) approximation. The directional Compton profiles and their anisotropic effects are also calculated using the same HF-LCAO approximation. The experimental spherical average profiles are found to be in good agreement with the corresponding HF-LCAO calculations and in qualitative agreement with Hartree-Fock free atom values. The present experimental isotropic and calculated directional profiles are also compared with the available experimental isotropic and directional Compton profiles using 59.54 and 159 keV γ-rays.

  18. Measurements of Lα, Lβ x-ray production cross sections of Pb by 16-40 keV electron impact

    International Nuclear Information System (INIS)

    Wu, Y; An, Z; Duan, Y M; Liu, M T; Tang, C H

    2007-01-01

    The measurement of L α , L β x-ray production cross sections for the element Pb (Z = 82) by 16-40 keV electron impact is reported in this paper. The target used in the experiment was prepared by evaporating the elemental Pb onto a thick pure carbon substrate. The effects of multiple scattering of electrons when penetrating the target film, of electrons reflected from the thick pure carbon substrate and of bremsstrahlung photons produced by the impact of incident electrons on the target are corrected using the Monte Carlo method. The experimental data, reported here for the first time in the energy region of interest, are compared with the plane-wave Born approximation theory with exchange, Coulomb and relativistic corrections. They are in good agreement

  19. Characteristics of Pitch Angle Distributions of 100s Kev Electrons in the Slot Region and Inner Radiation Belt­­­­­­­­

    Science.gov (United States)

    Zhao, H.; Li, X.; Blake, J. B.; Fennell, J.; Claudepierre, S. G.; Baker, D. N.; Jaynes, A. N.; Malaspina, D.

    2014-12-01

    The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-art pitch-angle-resolved data from the Magnetic Electron Ion Spectrometer (MagEIS) instrument onboard the Van Allen Probes, a detailed analysis of 100s keV electron PADs below L =4 is performed, in which the PADs is categorized into three types: normal (flux peaking at 90°), cap (exceedingly peaking narrowly around 90°) and 90°-minimum (lower flux at 90°) PADs. By examining the characteristics of the PADs of 460 keV electrons for over a year, we find that the 90°-minimum PADs are generally present in the inner belt (Lpitch angle scattering of hiss waves. Fitting the normal PADs into sinnα form, the parameter n is much higher below L=3 than that in the outer belt and relatively constant in the inner belt but changes significantly in the slot region (2mechanism can hardly explain the formation of 90°-minimum PADs at the center of inner belt. These new and compelling observations, made possible by the high-quality measurements of MagEIS, present a challenge for the wave modelers, and future work is still needed to fully understand them.

  20. Comparison between the 30- to 80-keV electron channels at ATS 6 and 1976-059A during conjunction and application to spacecraft charging prediction

    International Nuclear Information System (INIS)

    Garrett, H.B.; Schwank, D.C.; Higbie, P.R.; Baker, D.N.

    1980-01-01

    The ATS 6 satellite, during an orbital maneuver in September 1976, passed within a few hundred kilometers of the geosynchronous satellite 1976-059A. Analysis of the 30- to 80-keV electron data from the University of California at San Diego (UCSD) electrostatic analyzers on ATS 6 and the 30- to 300-keV electron data from the Los Alamos Scientific Laboratory instrument on 1976-059A during this period reveals good agreement between the two instruments even when the separation is +- 7 0 . The low-energy UCSD ion data from ATS 6 allow a simultaneous determination of the potential difference between ATS 6 and th ambient medium. Use of the 1976-059A electron data to approximate the ambient plasma electron density and temperature during these charging periods indicates sufficient information exists in order to estimate the maximum potentials to which ATS 6 charges in sunlight an eclipse. As data from 1976-059A and similar satellites are potentially available in real time, the information therefore exists to create a satellite charging index for the geosynchronous regime that would be valid within at least +- 7 0 longitude of the position of each measurement

  1. Measurements of L shell X-ray yields of thick Ag target by 6–29 keV electron impact

    International Nuclear Information System (INIS)

    Zhao, J.L.; Tian, L.X.; Li, X.L.; An, Z.; Zhu, J.J.; Liu, M.T.

    2015-01-01

    In this paper, the L shell X-ray yields for a thick Ag target have been measured at incident electron energies of 6–29 keV. The experimental values are compared with the Monte Carlo simulation results that are obtained by using the PENELOPE code, in which the inner-shell ionization cross sections by electron impact calculated in the theoretical frame of distorted wave Born approximation are used. The experimental and simulation values are in agreement with ∼10% difference. Meanwhile, the L shell X-ray production cross sections are also obtained based on the measured L shell X-ray yields for a thick Ag target in this paper, and are compared with other experimental Ag L shell X-ray production cross section data by electron and positron impact measured previously and some theoretical models. Some factors that could affect these comparisons are also discussed in this paper. - Highlights: • We measured L shell X-ray yields of thick Ag target by 6–29 keV electrons. • Our measured X-ray yields are in good agreement with the MC results with ∼10%. • L shell production cross sections are obtained based on the measured X-ray yields. • L shell production cross sections obtained are in good agreement with theories

  2. Incoherent scattering functions of 145 keV gamma rays by K-shell electrons in Y, Ag and Au

    International Nuclear Information System (INIS)

    Raghava Rao, A.; Ramana Reddy, S.V.S.; Premchand, K.; Narasimham, K.L.; Parthasaradhi, K.; Lakshminarayana, V.

    1982-01-01

    The values of incoherent scattering functions are determined experimentally for 145 keV gamma rays in elements Au, Ag and Y at scattering angles 40 0 , 70 0 and 100 0 , using a x-ray gamma coincidence technique. The corresponding theoretical values are obtained from the tabulations of Hubbell et al, and computed from the models of Jauch and Rohrlich and Shimizu et al. A comparison between the theoretical and experimental results showed that the non-relativistic approach adopted in the theory of Shimizu et al is inapplicable to the present cases. A gross agreement is noticed between the present experimental results and the other theoretical values. (author)

  3. Three-dimensional nanofabrication by electron-beam-induced deposition using 200-keV electrons in scanning transmission electron microscope

    International Nuclear Information System (INIS)

    Liu, Z.Q.; Mitsuishi, K.; Furuya, K.

    2005-01-01

    Attempts were made to fabricate three-dimensional nanostructures on and out of a substrate by electron-beam-induced deposition in a 200-kV scanning transmission electron microscope. Structures with parallel wires over the substrate surface were difficult to fabricate due to the direct deposition of wires on both top and bottom surfaces of the substrate. Within the penetration depth of the incident electron beam, nanotweezers were fabricated by moving the electron beam beyond different substrate layers. Combining the deposition of self-supporting wires and self-standing tips, complicated three-dimensional doll-like, flag-like, and gate-like nanostructures that extend out of the substrate were successfully fabricated with one-step or multi-step scans of the electron beam. Effects of coarsening, nucleation, and distortion during electron-beam-induced deposition are discussed. (orig.)

  4. Electron transfer in keV Li+-Na(3s, 3p) collisions: I. Atomic basis coupled-channel calculations

    International Nuclear Information System (INIS)

    Nielsen, S.E.; Dubois, A.

    1995-01-01

    Integral cross sections for electron capture from the ground state Na(3s) and excited states Na(3p) to Li(nlm), n = 2, 3, are calculated by the semiclassical impact-parameter method, using a two-centre atomic basis expansion. In the impact energy range 1-50 keV, results are analysed with particular emphasis on the alignment and orientation of initial and final p-states. At intermediate velocities opposite initial alignment effects are found for capture to n = 2 and n = 3 states, respectively. Orientation effects in state-to-state capture cross sections are predicted from oriented and tilted aligned initial states. (Author)

  5. Optimization of the laser-induced photoemission for the production of polarized electron beams at the 50-keV source of the Bonn accelerator facility ELSA

    International Nuclear Information System (INIS)

    Gowin, M.

    2001-10-01

    Medium energy experiments requiring circularly polarized photons (produced by Bremsstrahlung of longitudinally polarized electrons) have started at the electron stretcher ELSA in Bonn. To fulfill the demands of the experiment (GDH) the laser induced photoemission of the 50 keV electron source has been optimized. Systematic studies with a titan-sapphire laser to optimize the pulse structure of the laser pulse and the emitted spectral width has been done. Using a Be-InGaAs/Be-AlGaAs strained superlattice photocathode a beam polarization of 80% with a quantum efficiency of 0.4% has been obtained while producing a space charge limited 100 mA beam current. (orig.)

  6. EMSH program for calculating electron and photon transport through a matter at energies of 10 keV-1TeV

    International Nuclear Information System (INIS)

    Tayurskij, V.A.

    1989-01-01

    The EMSH program (Electro-Magnetic Shower) for the calculation of 1 keV-1 TeV electron and photon transport through a substance is described. The program is written in FORTRAN for the ES computers. Electron and positron bremsstrahlung, e - e - - and e + e - scattering, positron annihilation, production of e + e - -pairs by photons, photon. Compton scattering, photoelectric effect, photon Rayleigh scattering are taken into account during calculations. The cross sections of these processes are assigned with the 3-10% accuracy. Energy losses for atom ionization and excitation and bremsstrahlung, as well as multiple scattering are taken into account for charged particles. The program is used to calculate electron conversion into positrons, to estimate accelerator radiation background, to simulate electromagnetic showers in electromagntic calorimeters. 37 refs.; 15 figs

  7. Single-electron capture into Ar+ excited states in Ar2 + Na collision below 12 keV, 2

    International Nuclear Information System (INIS)

    Matsumoto, Atsushi; Tsurubuchi, Seiji; Okuno, Kazuhiko; Ohtani, Shunsuke; Iwai, Tsuruji.

    1979-08-01

    Excitation cross-sections are obtained for each term of the ArII nl-states (nl = 4p, 4p' and 4d) at 4 and 8 keV. The relative population distribution among the terms of a given nl-state can be interpreted in terms of statistics based on the building-up principle of molecule under radial coupling scheme. The relative population distribution among the multiplets in a given term is proportional to their statistical weight; spin-orbit recoupling at large internuclear separations is responsible for the population mechanism. The energy dependence of excitation cross-sections is discussed in connection with the Landau-Zener theory. (author)

  8. Electron capture and transfer-ionization processes in {sup 4}He{sup 2+}+Ar collision at 12.5 keV amu{sup -1}

    Energy Technology Data Exchange (ETDEWEB)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.; Benhenni, M. [Laboratoire Collisions, Agregats, Reactivite, IRSAMC, UMR 5589 CNRS and Universite Paul Sabatier, 31062 Toulouse Cedex (France)

    1998-05-14

    Electron emission in the {sup 4}He{sup 2+}+Ar collisional system has been investigated at 35 deg. and 12.5 keV amu{sup -1} collision velocity, in coincidence with the recoil target ion charges. Direct single ionization is found to be negligible with respect to single-electron capture. Contributions of transfer-ionization processes are stressed in the production of Ar{sup 2+} to Ar{sup 4+} ions; those of direct ionization, double excitation of the target and double capture into autoionization states of helium are instead found to be much less probable. Among the two-electron processes which explain the formation of Ar{sup 2+} ions, the double capture into autoionizing states of helium remains unimportant with respect to a pure transfer ionization process (one captured electron plus one ionized electron). The measured predominant production of Ar{sup 3+} ions illustrates the role played by three-electron processes, mainly a two-electron transfer accompanied by a single-target ionization. Finally, the formation of Ar{sup 4+} ions is connected with more complex transfer ionization processes. A qualitative analysis of these results is made within the quasimolecular approach. (author). Letter-to-the-editor.

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

    Science.gov (United States)

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

    1971-01-01

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

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

    International Nuclear Information System (INIS)

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

    2005-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Gowda, Shivalinge [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India); Krishnaveni, S. [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India); Gowda, Ramakrishna [Department of Studies in Physics, University of Mysore, Manasagangotri, Mysore 570 006 (India)]. E-mail: ramakrishnagowda@yahoo.com

    2005-10-15

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

  12. Construction of electron beam machine 350 keV/10 mA for multipurpose application of thin sample at P3TM-BATAN

    International Nuclear Information System (INIS)

    Darsono

    2004-01-01

    Research and development starting in 1984 of electron beam technology in Indonesia is first briefly presented. BATAN assigned to the Yogyakarta Nuclear Center the project of constructing an electron beam machine of 350 keV/10 mA for multipurpose applications especially for thin samples for duration of five years. The main objective of the project was the young scientists training and demonstration purposes in operation and maintenance of the machine. The engineers have learned through experience of the low energy ion accelerator (150 kV) many techniques to construct the system component such as E-gun, high voltage, vacuum, beam optics, scanning horn and window, beam stopper, and conveyer as well as the embedded control system. Because of the window cooling system, the uses of the machine are limited for irradiating a thin sample of plastics, hydrogel, powder, or liquid. Future plans for modification of the machine are stated. (S. Ohno)

  13. Development of an intermediate energy heavy-ion micro-beam irradiation system

    International Nuclear Information System (INIS)

    Song Mingtao; Wang Zhiguang; He Yuan; Gao Daqing; Yang Xiaotian; Liu Jie; Su Hong; Man Kaidi; Sheng Li'na

    2008-01-01

    The micro-beam irradiation system, which focuses the beam down the micron order and precisely delivers a predefined number of ions to a predefined spot of micron order, is a powerful tool for radio-biology, radio-biomedicine and micromachining. The Institute of Modern Physics of Chinese Academy of Sciences is developing a heavy-ion micro-beam irradiation system up to intermediate energy. Based on the intermediate and low energy beam provided by Heavy Ion Research Facility of Lanzhou, the micro-beam system takes the form of the magnetic focusing. The heavy-ion beam is conducted to the basement by a symmetrical achromatic system consisting of two vertical bending magnets and a quadrupole in between. Then a beam spot of micron order is formed by magnetic triplet quadrupole of very high gradient. The sample can be irradiated either in vacuum or in the air. This system will be the first opening platform capable of providing heavy ion micro-beam, ranging from low (10 MeV/u) to intermediate energy (100 MeV/u), for irradiation experiment with positioning and counting accuracy. Target material may be biology cell, tissue or other non-biological materials. It will be a help for unveiling the essence of heavy-ion interaction with matter and also a new means for exploring the application of heavy-ion irradiation. (authors)

  14. Angular distribution of thick-target bremsstrahlung produced by electrons with initial energies ranging from 10 to 20 keV incident on Ag

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales, D.; Cavness, B.; Williams, S. [Department of Physics, Angelo State University, San Angelo, Texas 76909 (United States)

    2011-11-15

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

  15. The emission of characteristic and non-characteristic x-rays from collisions of 10-22 keV electrons with argon

    Energy Technology Data Exchange (ETDEWEB)

    Singh, R K; Shanker, R [Atomic Physics Laboratory, Department of Physics, Banaras Hindu University, Varanasi-221 005 (India)

    2003-07-28

    Measurements of the emission cross sections of the characteristic and the non-characteristic x-rays produced from collisions of 10-22 keV electrons with Ar atoms are presented. The relative cross sections for Ar K-shell ionization as a function of impact energy are shown to yield satisfactory agreement (within the experimental uncertainty) with Born-Ochkur calculations and with results obtained from an empirical formula proposed by Hombourger (1998 J. Phys. B: At. Mol. Opt. Phys. 31 3693). Furthermore, the double differential cross sections of bremsstrahlung photons emitted from 10-22 keV e{sup -}-Ar collisions as a function of impact energy for different photon energies were measured. The shape of the experimental bremsstrahlung cross section function is found to exhibit good agreement with the theoretical calculations of Kissel et al (1983 At. Data Nucl. Data Tables 28 381) within the experimental uncertainty. In addition, the shape of the angular distributions of the bremsstrahlung is in accord with the calculations of Kissel et al and those of the modified Sommerfeld (Kulenkampff et al 1959 Z. Phys. 157 275) formula.

  16. Small-sized accelerating tube for electron acceleration to 500 keV at pulse duration of 2 ns

    International Nuclear Information System (INIS)

    Pavlovskaya, N.G.; Ehl'yash, S.L.; Dron', N.A.; Sloeva, G.N.

    1978-01-01

    The design and characteristics (current, voltage, current density, electron beam structure, energy spectrum, and dose rate) of a soldered small-size two-electrode 600 kV accelerating tube are considered. A six-stage Arkadiev-Marx generator is the pulse high-voltage supply of nanosecond duration. When using a cathode (diameter of 8 mm) made of tantalum foil 0.02 mm thick and with interelectrode gap of 10 mm, the amplitude of the electron beam current beyond the beryllium anode equals to 1040 A under maximum voltage of 490 kV, current pulse duration of 2 ns, number of electrons is 10 13 . The increased electron density on the anode in a spot of 4 mm in diameter is observed; the current density in the spot reaches 1 kA/cm 2 . The electron energy in the beam beyond the anode is as much as 0.6-0.8 J per pulse, and the dose rate near the outer surface of the outlet window is 10 14 -10 15 rad/s. The use of an intensifying oil spark gap is shown to increase radiation hardness. The accelerating tube provides more than 10 5 shots in a single-switching mode

  17. Coulomb focusing and ''path'' interference of autoionizing electrons produced in 10 keV He+ + He collisions

    International Nuclear Information System (INIS)

    Swenson, J.K.; Burgdoerfer, J.; Meyer, F.W.; Havener, C.C.; Gregory, D.C.; Stolterfoht, N.

    1991-01-01

    Autoionizing electrons emitted following low energy ion-atom collisions may scatter significantly from the receding spectator ion's attractive Coulomb field. In such cases the observed electron intensity is ''focused'' in the direction of the scattering ion as a result of the effective compression of the emission solid angle. In addition, interference may occur between trajectories, corresponding to electrons scattering around opposite sides of the ion, which lead to the same final laboratory electron energy and emission angle. This Coulomb ''path'' interference mechanism manifests itself in the uncharacteristically rapid angular dependence of the He target 2s 2 1 S autoionizing state measured near 0 degree following low energy He + + He collisions. A classical trajectory model for Coulomb focusing is presented and a semi-classical approximation is used to model the Coulomb ''path'' interference mechanism. In this description we account for the evolution of the phase of the autoionizing state until its decay and the path dependence of the amplitude of the emitted electron following decay of the autoionizing state. Calculated model lineshapes, which include contributions from adjacent overlapping resonances, reproduce quite well the angular dependence observed in the data near 0 degree. 14 refs., 7 figs

  18. Electron transfer in keV Li+-Na*(3p) collisions: Pt.2. Molecular basis model

    International Nuclear Information System (INIS)

    Machholm, M.; Courbin, C.

    1996-01-01

    The velocity dependence of state-to-state integral cross sections for electron transfer and excitation in Li + -Na(3s, 3p) collisions is studied in the 0.05-0.3 au velocity range using the impact parameter semi-classical method and a 28-state molecular orbital basis model including a common translation factor. The initial orbital alignment dependence of electron transfer is in fair agreement with recent experiments and with atomic orbital model calculations. The main electron transfer channel from Na*(3p) is to the Li*(2p) states. The integral cross sections from an aligned or oriented Na*(3p) state to an aligned or oriented Li*(2p) state and vice versa and the corresponding alignment and orientation parameters are presented as a function of the impact velocity. (author)

  19. On the Emission of Electrons from Solid H_2 and D_2 by Bombardment with 1-3 keV Electrons up to Very Large Angles of Incidence

    DEFF Research Database (Denmark)

    Schou, Jørgen; Sørensen, H.

    1982-01-01

    at the largest angles. The results agree well with the existing qualitative tendencies described in the literature. The variation with the angle of incidence shows a fair agreement with an estimate based on data for the angular distribution of electrons ejected from ionized hydrogen molecules. In addition......Electron emission, i.e. electron reflection (ER) and secondary electron emission (SEE), was studied for solid H2 and D2 for oblique incidence of 1-3 keV electrons up to an angle of incidence θ of 83°. The ER coefficient η was small at low angles, and rose rapidly with increasing θ above 60......, an ionization cascade treatment leads to an expression for the behavior of the yield of those secondary electrons that are generated directly by the primaries. The agreement with experimental data is good...

  20. Electron capture by He2+ ions in collisions with H and H2 at impact energies below 10 keV

    International Nuclear Information System (INIS)

    Nutt, W.L.; McCullough, R.W.; Brady, K.; Shah, M.B.; Gilbody, H.B.

    1978-01-01

    Total cross sections for the process He 2+ + H(1s) → He + (Σn, 1) + H + involving capture into all final bound states of He + have been determined for 3 He 2+ ions in the range 1.5-9.0 keV using a furnace-target technique previously employed for similar measurements at higher impact energies. Measured cross sections are considerably smaller than those measured previously by Fite et al (Proc. R.Soc.; A268:527 (1962)) and are in better accord with recent theoretical estimates. A likely explanation for the discrepancy is given in terms of the corresponding cross sections for electron capture in He 2+ -H 2 collisions which have also been determined. (author)

  1. New elastic electron scattering factors for the elements for incident energies of 10, 40, 60, and 90 keV

    International Nuclear Information System (INIS)

    Ross, A.W.; Fink, M.

    1986-01-01

    An improved set of scattering factors for all neutral elements has bee completed for inclusion in the new edition of the International Tables of X-ray Crystallography . These calculations are compared with the former electron scattering factors and the deviations between the two are discussed

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

    International Nuclear Information System (INIS)

    Cobut, V.; 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. Developments at an electrostatic cryogenic storage ring for electron-cooled keV energy ion beams

    International Nuclear Information System (INIS)

    Vogel, Stephen

    2016-01-01

    This work is devoted to final setup activities and the commissioning of an electrostatic cryogenic storage ring (CSR) at the Max Planck Institute for Nuclear Physics (MPIK) in Heidelberg. The first cryogenic operation of CSR in 2015 has been documented and characterized using a set of non-destructive beam diagnostic tools developed within this work. These are (1) the current pick-up system for the determination of the current of the stored ion beam and its velocity, (2) a position pick-up system for measuring the transverse position of the ion beam center at six symmetric locations of the storage ring circumference, and (3) a Schottky pick-up system for the monitoring of coasting ion beams. Despite the requirements imposed by the cryogenic operation, the developed diagnostic system demonstrated its full functionality. First characterizations of the storage ring properties and the performance of the diagnostic system are presented. Based on previous work, an electron cooling system for CSR has been developed and largely realized. With the implementation into CSR in 2016, the electron cooler will enhance the storage ring into a unique experimental facility for electron-ion collision studies. With this CSR is on the track to become the first cryogenic storage ring featuring actively cooled ion beams.

  4. Quite time convection electric field properties derived from keV electron measurements at the inner edge of the plasma sheet by means of GEOS 2

    International Nuclear Information System (INIS)

    Reme, H.; Kremser, G.; Bahnsen, A.; Jespersen, M.; Hultqvist, B.; Borg, H.; Holmgren, L.Aa.

    1981-04-01

    From an analysis of the local time distribution of the electron upper energy limit reached by the geostationary satellite GEOS 2 in cutting through the innermost part of the electron plasma sheet during fairly quite condition the following results have been obtained, among others: An electric field model given by E = -grad(AR 4 sinphi), with the dusk singular point of the forbidden region boundary at 1500, instead of at 1800 MLT, is in quite good agreement with the observations. This means that effects due to the shielding by the hot plasma of the inner magnetosphere from the convection electric field are quite strong in situations of low disturbance level. The quiet time convection electric field strength at 2100 MLT in the geostationary orbit obtained from this analysis varies in the range 0.15 - 0.3 keV/Rsub(e). Six hours earlier or later in the satellite orbit the convection field is 4 times stronger. Also when the convection field varies, some information about its magnitude can be obtained from the keV electron measurements. (author)

  5. Shifting of the electron-capture-to-the-continuum peak in proton-helium collisions at 10 and 20 keV

    International Nuclear Information System (INIS)

    Bhattacharya, S.; Deb, N.C.; Roy, K.; Sahoo, S.; Crothers, D.S.F.

    2005-01-01

    A refined theoretical approach has been developed to study the double-differential cross sections (DDCS's) in proton-helium collisions as a function of the ratio of ionized electron velocity to the incident proton velocity. The refinement is done in the present coupled-channel calculation by introducing a continuum distorted wave in the final state coupled with discrete states including direct as well as charge transfer channels. It is confirmed that the electron-capture-to-the-continuum (ECC) peak is slightly shifted to a lower electron velocity than the equivelocity position. Comparing measurements and classical trajectory Monte Carlo (CTMC) calculations at 10 and 20 keV proton energies, excellent agreement of the ECC peak heights is achieved at both energies. However, a minor disagreement in the peak positions between the present calculation and the CTMC results is noted. A smooth behavior of the DDCS is found in the present calculation on both sides of the peak whereas the CTMC results show some oscillatory behavior particularly to the left of the peak, associated with the statistical nature of CTMC calculations

  6. 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....

  7. Measurement results of electron fluxes with energy of more or equal to 40 keV and not related to solar flares by using the ''Mars-7'' automatic interplanetary station

    International Nuclear Information System (INIS)

    Alekseev, N.V.; Vakulov, P.V.; Vologdin, N.I.; Logachev, Yu.I.

    1982-01-01

    Measurement results of electron fluxes of energy of more or equal to 40 keV performed by the Mars-7 automatic interplanetary station in the period from August 1973 till March 1974 are given. The modulation of intensity by different velocity plasma fluxes of solar wind was found, the electron intensity increasing tenfold for the time of measuring and reaches the maximum in February 1974. In the maximum of intensity the anisotropy is negative. The analysis of observations shows that in interplanetary space electron fluxes of Jupiter at least energies from 40 keV and according to the data of other authors of up to approximately 6 MeV are present. Leading strike edges of different velocity plasma fluxes of solar wind affect significantly electron fluxes of Jupiter - when the source and the station are on different sides of the edge, the intensity decreases 10-100 times. If some different velocity plasma fluxes are simultaneously in space as it was in October-November 1973, then the structure of electron flux of energy >= 40 keV becomes very complicated.The different retardation in occurance of maximums of electrons approximately 6 MeV energy and with Esub(e) >= 40 keV points to different factors of cross diffusion of these electrons

  8. Study of Corona Discharge on 160 KeV, 10 mA Electron Accelerator Facility Using FEM

    International Nuclear Information System (INIS)

    Ghazali, Abu Bakar Mhd; Sobri, Rokiah Mohd

    2008-01-01

    This paper describes a method to verify the overall design of our electron accelerator. It is free from corona or spark discharge phenomenon. This locally designed electron accelerator facility is located at Nuclear Malaysia Complex, Bangi, Selangor. In this study, we describe the geometry of the pressure vessel filled with SF 6 gas at 2 atm to enclose the high voltage area of the accelerating tube. The Poisson's equation is used to calculate the contours of the electric field that is created between the cathode of -160 kV maximum and the wall of the vessel. The nearest sharp edge between the cathode and the pressure wall is 163 mm apart. The calculation is based on finite element method (FEM) for electrostatic charges in order to obtain an electric field contour in two-dimensional plane. We found that the surface charge density of the cathode is 1.1x10 -5 C/m 2 for the corona glowing seen at -90 kV. Moreover, the highest electric field near to (about 5 mm from) the sharp edge is about 2.7 MV/m, which is less than the dielectric strength of SF 6 gas, i.e. 6 MV/m and therefore, it proved that our design of the pressure vessel is save from corona or spark discharges

  9. Study of Corona Discharge on 160 KeV, 10 mA Electron Accelerator Facility Using FEM

    Science.gov (United States)

    Ghazali, Abu Bakar Mhd; Sobri, Rokiah Mohd

    2008-05-01

    This paper describes a method to verify the overall design of our electron accelerator. It is free from corona or spark discharge phenomenon. This locally designed electron accelerator facility is located at Nuclear Malaysia Complex, Bangi, Selangor. In this study, we describe the geometry of the pressure vessel filled with SF6 gas at 2 atm to enclose the high voltage area of the accelerating tube. The Poisson's equation is used to calculate the contours of the electric field that is created between the cathode of -160 kV maximum and the wall of the vessel. The nearest sharp edge between the cathode and the pressure wall is 163 mm apart. The calculation is based on finite element method (FEM) for electrostatic charges in order to obtain an electric field contour in two-dimensional plane. We found that the surface charge density of the cathode is 1.1×10-5 C/m2 for the corona glowing seen at -90 kV. Moreover, the highest electric field near to (about 5 mm from) the sharp edge is about 2.7 MV/m, which is less than the dielectric strength of SF6 gas, i.e. 6 MV/m and therefore, it proved that our design of the pressure vessel is save from corona or spark discharges.

  10. Calculations of elastic, ionization and total cross sections for inert gases upon electron impact: threshold to 2 keV

    Energy Technology Data Exchange (ETDEWEB)

    Vinodkumar, Minaxi [V P and R P T P Science College, Vallabh Vidyanagar 388 120, Gujarat (India); Limbachiya, Chetan [P S Science College, Kadi 382 715, Gujarat (India); Antony, Bobby [Department of Environmental, Earth and Atmospheric Sciences, University of Massachusetts Lowell, 265 Riverside Street, Lowell, MA 01854-5045 (United States); Joshipura, K N [Department of Physics, Sardar Patel University, Vallabh Vidyanagar 388 120, Gujarat (India)

    2007-08-28

    In this paper we report comprehensive calculations of total elastic (Q{sub el}), total ionization (Q{sub ion}) and total (complete) cross sections (Q{sub T}) for the impact of electrons on inert gases (He, Ne, Ar, Kr and Xe) at energies from about threshold to 2000 eV. We have employed the spherical complex optical potential (SCOP) formalism to evaluate Q{sub el} and Q{sub T} and used the complex spherical potential-ionization contribution (CSP-ic) method to derive Q{sub ion}. The dependence of Q{sub T} on polarizability and incident energy is presented for these targets through an analytical formula. Mutual comparison of various cross sections is provided to show their relative contribution to the total cross sections Q{sub T}. Comparison of Q{sub T} for all these targets is carried out to present a general theoretical picture of collision processes. The present calculations also provide information, hitherto sparse, on the excitation processes of these atomic targets. These results are compared with available experimental and other theoretical data and overall good agreement is observed.

  11. PIXE/PIGE characterisation of emeralds using an external micro-beam

    International Nuclear Information System (INIS)

    Calligaro, T.; Dran, J.-C.; Poirot, J.-P.; Querre, G.; Salomon, J.; Zwaan, J.C.

    2000-01-01

    A large collection of emeralds of various occurrences has been analysed by PIXE/PIGE in view to establish a compositional database. Major elements (Be, Si, Al) and trace elements (Li, F, Na, Mg, Ca, Rb, Cs and transition metals) are determined using an external 3 MeV proton micro-beam. Elemental micro-mapping permits to select the useful provenance tracers. This database was applied to infer the origin of several ancient emeralds set on historical jewels

  12. Ionization cross sections of the Au L subshells by electron impact from the L3 threshold to 100 keV

    Science.gov (United States)

    Barros, Suelen F.; Vanin, Vito R.; Maidana, Nora L.; Martins, Marcos N.; García-Alvarez, Juan A.; Santos, Osvaldo C. B.; Rodrigues, Cleber L.; Koskinas, Marina F.; Fernández-Varea, José M.

    2018-01-01

    We measured the cross sections for Au Lα, Lβ, Lγ, Lℓ and Lη x-ray production by the impact of electrons with energies from the L3 threshold to 100 keV using a thin Au film whose mass thickness was determined by Rutherford Backscattering Spectrometry. The x-ray spectra were acquired with a Si drift detector, which allowed to separate the components of the Lγ multiplet lines. The measured Lα, Lβ, {{L}}{γ }1, L{γ }{2,3,6}, {{L}}{γ }{4,4\\prime }, {{L}}{γ }5, {{L}}{\\ell } and Lη x-ray production cross sections were then employed to derive Au L1, L2 and L3 subshell ionization cross sections with relative uncertainties of 8%, 7% and 7%, respectively; these figures include the uncertainties in the atomic relaxation parameters. The correction for the increase in electron path length inside the Au film was estimated by means of Monte Carlo simulations. The experimental ionization cross sections are about 10% above the state-of-the-art distorted-wave calculations.

  13. Preliminary test of remote manual instrumentation & control type system for vacuum unit of 350 KeV / 10 mA electron beam machine

    International Nuclear Information System (INIS)

    Sudiyanto

    2003-01-01

    Remote manual instrumentation & control type for vacuum unit of 350 KeV/10 mA Electron Beam Machine is being completed. The system consisting of a remote manual controlled and a remote acquisition system. A remote manual (50 m) controlled is based on the on/off status of 220 Volt terminal supply for pneumatic valves and vacuum pumps, in this case the power supply switch of pneumatic valves and pumps have already been selected On. Remote acquisition of vacuum level can be done by using a CCTV camera which is place in front of the panning gauge and TGP.300 Balzer unit.The CCTV system equipped with 6 cameras, one TV monitor and a multiplexer unit to arranged a selected picture on it. One of the camera was mounted on the rotator unit, it can be controlled (rotating left / right) for different monitoring orientations required by using infrared controller. A trial test of the remote manual control system for vacuum unit of the Electron Beam Machine showed a good performance. (author)

  14. A NEXAFS and mass spectrometry study of cysteine, cystine and insulin irradiated with intermediate energy (0.8 keV) electrons

    Energy Technology Data Exchange (ETDEWEB)

    Simões, G., E-mail: simoes.grazieli@gmail.com [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil); Rodrigues, F.N. [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil); Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Maracanã, 20270-021 Rio de Janeiro (Brazil); Bernini, R.B. [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil); Instituto Federal de Educação, Ciência e Tecnologia do Rio de Janeiro, Duque de Caxias, 25050-100 Rio de Janeiro (Brazil); Castro, C.S.C. [Instituto Nacional de Metrologia, Qualidade e Tecnologia – Inmetro, 25250-020 Rio de Janeiro (Brazil); Souza, G.G.B. de, E-mail: gerson@iq.ufrj.br [Instituto de Química, Universidade Federal do Rio de Janeiro, Cidade Universitária, 21941-909 Rio de Janeiro (Brazil)

    2014-03-01

    Highlights: • Structural modifications in sulfur containing biomolecules were investigated. • Significant modifications were observed in insulin irradiated NEXAFS spectra. • Degradation of insulin can be observed even at low temperature. • Alterations in insulin spectrum were characterized according to the state of sulfur. - Abstract: We have performed a NEXAFS (S 1s) and mass spectrometry study of solid samples of cysteine, cystine and insulin irradiated with 0.8 keV electrons. The measured mass spectra point out to processes of desulfurization, deamination, decarbonylation and decarboxylation in the irradiated biomolecules. Electron beam irradiation was also conducted at low temperatures in order to evaluate the possible contribution from thermal degradation processes. The NEXAFS spectra of irradiated cysteine and cystine did not show substantial changes when compared to the same spectra obtained using non-irradiated samples. The sulfur K-edge photoabsorption spectrum of irradiated insulin, however, showed clear modifications when compared to the spectrum of the non-irradiated protein, even when the irradiation was conducted at low temperature. Using an empirical combination of the photoabsorption spectra of cysteine and cystine (which are associated respectively with reduced and oxidized forms of sulfur) we have been able to reproduce the absorption spectrum of irradiated insulin.

  15. Lα and Mαβ X-ray production cross-sections of Bi by 6-30 keV electron impact

    Science.gov (United States)

    Liang, Y.; Xu, M. X.; Yuan, Y.; Wu, Y.; Qian, Z. C.; Chang, C. H.; Mei, C. S.; Zhu, J. J.; Moharram, K.

    2017-12-01

    In this paper, the Lα and Mαβ X-ray production cross-sections for Bi impacted by 6-30 keV electron have been measured. The experiments were performed at a Scanning Electron Microscope equipped with a silicon drift detector. The thin film with thick C substrate and the thin film deposited on self-supporting thin C film were both used as the targets to make a comparison. For the thick carbon substrate target, the Monte Carlo method has been used to eliminate the contribution of backscattering particles. The measured data are compared with the DWBA theoretical model and the experimental results in the literature. The experimental data for the thin film with thick C substrate target and the thin film deposited on self-supporting thin C film target are within reasonable gaps. The DWBA theoretical model gives good fit to the experimental data both for L- and M- shells. Besides, we also analyze the reasons why the discrepancies exist between our measurements and the experimental results in the literature.

  16. Nonlinear behavior of capacitive micro-beams based on strain gradient theory

    International Nuclear Information System (INIS)

    Fathalilou, Mohammad; Sadeghi, Morteza; Rezazadeh, Ghader

    2014-01-01

    This paper studies the size dependent behavior of materials in MEMS structures. This behavior becomes noticeable for a structure when the characteristic size such as thickness or diameter is close to its internal length-scale parameter and is insignificant for the high ratio of the characteristic size to the length-scale parameter, which is the case of the silicon base micro-beams. However, in some types of micro-beams like gold or nickel bases, the size dependent effect cannot be overlooked. In such cases, ignoring this behavior in modeling will lead to incorrect results. Some previous researchers have applied classic beam theory on their models and imposed a considerable hypothetical value of residual stress to match their theoretical results with the experimental ones. The equilibrium positions or fixed points of the gold and nickel micro-beams are obtained and shown that for a given DC voltage, there is a considerable difference between the obtained fixed points using classic beam theory, modified couple stress theory, and modified strain gradient theory. In addition, it is shown that the calculated static and dynamic pull-in voltages using higher order theories are much closer to the experimental results and are higher several times than those obtained by classic beam theory.

  17. Determination of Psub(K) values to the 172, 103 and 97 keV levels and the fluorescence yield. omega. sub(K) of Eu after electron capture by /sup 153/Gd

    Energy Technology Data Exchange (ETDEWEB)

    Singh, K; Grewal, B S; Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

    1985-03-01

    From an analysis of K x-ray-..gamma..-ray sum peaks observed with an intrinsic Ge detector the K-capture probabilities (Psub(K)) to the 172, 103 and 97 keV levels in the decay of /sup 153/Gd have been determined; these yield an electron-capture energy Qsub(EC)=245 +- 2. The K-capture probability to the 172 keV level differs significantly from that found in the literature. With these results the K-shell fluorescence yield of Eu is ..omega..sub(K)=0.935 +- 0.019.

  18. Angular dependence of Kβ/Kα intensity ratios of thick Ti and Cu pure elements from 10-25 keV electron bombardment

    Science.gov (United States)

    Singh, B.; Kumar, S.; Prajapati, S.; Singh, B. K.; Llovet, X.; Shanker, R.

    2018-02-01

    Measurements yielding the first results on angular dependence of Kβ/Kα X-ray intensity ratios of thick Ti (Z = 22) and Cu (Z = 29) targets induced by 10-25 keV electrons are presented. The measurements were done by rotating the target surface around the electron beam direction in the angular detection range 105° ≤ θ ≤ 165° in the reflection mode using an energy dispersive Si PIN photodiode detector. The measured angular dependence of Kβ/Kα intensity ratios is shown to be almost isotropic for Ti and Cu targets for the range of detection angles, 105° ≤ θ ≤ 150°, while there is a very weak increase beyond 150° for both targets. No dependence of Kβ/Kα intensity ratios on impact energy is observed; while on average, the value of the Kβ/Kα X-ray intensity ratio for Cu is larger by about 8% than that for Ti, which indicates a weak Z-dependence of the target. The experimental results are compared with those obtained from PENELOPE MC calculations and from the Evaluated Atomic Data Library (EADL) ratios. These results on Kβ/Kα X-ray intensity ratios are found to be in reasonable agreement in the detection angle range 105° ≤ θ ≤ 150° to within uncertainties, whereas the simulation and experimental results show a very slight increase in the intensity ratio with θ as the latter attains higher values. The results presented in this work provide a direct check on the accuracy of PENELOPE at oblique incidence angles for which there has been a lack of measurements in the literature until now.

  19. Design of Control System Device for Electron Gun Power Supply of 350 keV/10 mA Electron Beam Machine

    International Nuclear Information System (INIS)

    Eko Priyono; Budi Santosa; Taxwim

    2003-01-01

    The electron gun power supply control system of electron beam machine has been designed. Using this design regulator device for the electron gun power supply will be constructed. This regulator device was designed that it can be operated manually or automatically. Beside that, this was also provided with the safety system which is useful to scram the MBE when something wrong happened. The main components of the device are remote data communication system using infra red and fiber optic module, DC motor driver system, regulated transformer coupled by DC motor and operation panel system. (author)

  20. Scanning ion micro-beam techniques for measuring diffusion in heterogeneous materials

    International Nuclear Information System (INIS)

    Jenneson, P.M.; Clough, A.S.

    1998-01-01

    A raster scanning MeV micro-beam of 1 H + or 3 He + ions was used to study the diffusion of small molecules in heterogeneous materials. The location of elemental contaminants (heavier than Lithium) in polymer insulated cables was studied with 1 H micro-Particle Induced X-ray Emission (μPIXE). Concentration profiles of a deuterated molecule in a hair fibre were determined with 3 He micro-Nuclear Reaction Analysis (μNRA). Chlorine and heavy water (D 2 0) diffusion into cement pastes were profiled using a combination of 3 He μPIXE and μNRA. (authors)

  1. Measurement of angular distributions of K x-ray intensity of Ti and Cu thick targets following impact of 10–25 keV electrons

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Bhupendra; Kumar, Sunil; Prajapati, Suman; Singh, Bhartendu K. [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India); Llovet, Xavier [Scientific and Technological Centers, Universitat de Barcelona, Lluís Solé i Sabarís 1-3, 08028 Barcelona (Spain); Shanker, R., E-mail: shankerorama@gmail.com [Atomic Physics Laboratory, Department of Physics, Institute of Science, Banaras Hindu University, Varanasi 221005 (India)

    2017-04-15

    Highlights: • New results on the angular distributions of relative intensities of K-X-rays lines of Ti and Cu thick targets under electron bombardment are reported. • An increase of relative intensity of Kα and Kβ X-ray lines has been found to be about 60–70% in the detection range θ = 105{sup 0}–165{sup 0}. • There is a slight impact energy dependence of Cu Kα X-ray line. • A reasonable agreement between experimental and PENELOPE MC Calculations are obtained. - Abstract: We present new results on angular distributions of the relative intensity of K{sub α} and K{sub β} x-ray lines of thick targets of Ti (Z = 22) and Cu (Z = 29) pure elements following impact of 10–25 keV electrons. The angular measurements of the K x-radiations were accomplished by rotating the target surface with respect to the electron beam direction. The x-rays emerging from the target surface in reflection mode were detected by an energy dispersive Si P-I-N photodiode detector. The resulting variation of the relative intensity of the characteristic lines as a function of angle of detection and impact energy has been found to be anisotropic and it is considered to arise due to change in path lengths at a given incidence angle α for the photons generated by direct as well as by indirect K shell ionization processes. The measured angular variations of relative intensity of K{sub α} and K{sub β} x-ray lines of both targets are found to increase by about 60–70% in going from θ = 105{sup 0} to 165{sup 0} at a given impact energy; however there is a slight indication of impact energy dependence of Cu K{sub α} x-ray line as also noted by the earlier workers. We compare the experimental results with those obtained by Monte Carlo simulations using PENELOPE calculations; the agreement between experiment and theory is found to be satisfactory within uncertainties involved in the measurements and the theoretical results.

  2. Investigation of the effective atomic numbers of dosimetric materials for electrons, protons and alpha particles using a direct method in the energy region 10 keV-1 GeV: a comparative study.

    Science.gov (United States)

    Kurudirek, Murat; Aksakal, Oğuz; Akkuş, Tuba

    2015-11-01

    A direct method has been used for the first time, to compute effective atomic numbers (Z eff) of water, air, human tissues, and some organic and inorganic compounds, for total electron proton and alpha particle interaction in the energy region 10 keV-1 GeV. The obtained values for Z eff were then compared to those obtained using an interpolation procedure. In general, good agreement has been observed for electrons, and the difference (%) in Z eff between the results of the direct and the interpolation method was found to be energy range from 10 keV to 1 MeV. More specifically, results of the two methods were found to agree well (Dif. energy region with respect to the total electron interaction. On the other hand, values for Z eff calculated using both methods for protons and alpha particles generally agree with each other in the high-energy region above 10 MeV.

  3. WE-E-BRE-08: Impact of IUdR in Rat 9L Glioma Cell Survival for 25–35 KeV Photo-Activated Auger Electron Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez, D; Hogstrom, K [Louisiana State University, Baton Rouge, LA (United States); Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States); Brown, T; Dugas, J; Varnes, M [Mary Bird Perkins Cancer Center, Baton Rouge, LA (United States); Matthews, K [Louisiana State University, Baton Rouge, LA (United States)

    2014-06-15

    Purpose: To determine the biological effect from Auger electrons with 9% and 18% iododeoxyuridine (IUdR) incorporated into the DNA of rat 9L glioma cells at photon energies above and below the K-edge of iodine (33.2 keV). Methods: Rat 9L glioma cell survival versus dose curves with 0%, 9%, and 18% thymidine replacement with IUdR were measured using four irradiation energies (4 MV x-rays; monochromatic 35, 30, and 25 keV synchrotron photons). For each of 11 conditions (Energy, %IUdR) survival curves were fit to the data (826 cell cultures) using the linear-quadratic model. The ratio of doses resulting in 10% survival gave sensitization enhancement ratios (SER10) from which contributions due to linear-energy transfer (LET), radiosensitization (RS), and Auger effect (AE) were extracted. Results: At 35, 30, and 25 keV, SER10,LET values were 1.08±0.03, 1.22±0.02, and 1.37±0.02, respectively. At 4 MV SER10,RS values for 9% and 18% IUdR were 1.28±0.02 and 1.40±0.02, respectively. Assuming LET effects are independent of %IUdR and radiosensitization effects are independent of energy, SER10,AE values for 18% IUdR at 35, 30, and 25 keV were 1.35±0.05, 1.06±0.03, and 0.98±0.03, respectively; values for 9% IUdR at 35 and 25 keV were 1.01±0.04 and 0.82±0.02, respectively. Conclusion: For 18% IUdR the radiosensitization effect of 1.40 and the Auger effect of 1.35 at 35 keV are equally important to the combined effect of 1.90. No measureable Auger effect was observed for energies below the K-edge at 20 and 25 keV, as expected. The insignificant Auger effect at 9% IUdR was not expected. Additional data (40–70 keV) and radiobiological modeling are being acquired to better understand the energy dependence of Auger electron therapy with IUdR. Funding support in part by the National Science Foundation Graduate Research Fellowship Program and in part by Contract No. W81XWH-10-1-0005 awarded by the U.S. Army Research Acquisition Activity. This paper does not necessarily

  4. Study of squeeze film damping in a micro-beam resonator based on micro-polar theory

    Directory of Open Access Journals (Sweden)

    Mina Ghanbari

    Full Text Available In this paper, squeeze film damping in a micro-beam resonator based on micro-polar theory has been investigated. The proposed model for this study consists of a clamped-clamped micro-beam bounded between two fixed layers. The gap between the micro-beam and layers is filled with air. As fluid behaves differently in micro scale than macro, the micro-scale fluid field in the gap has been modeled based on micro-polar theory. Equation of motion governing transverse deflection of the micro- beam based on modified couple stress theory and also non-linear Reynolds equation of the fluid field based on micropolar theory have been non-dimensionalized, linearized and solved simultaneously in order to calculate the quality factor of the resonator. The effect of micropolar parameters of air on the quality factor has been investigated. The quality factor of the of the micro-beam resonator for different values of non-dimensionalized length scale of the beam, squeeze number and also non-dimensionalized pressure has been calculated and compared to the obtained values of quality factor based on classical theory.

  5. Complete synchronization condition in a network of piezoelectric micro-beam

    International Nuclear Information System (INIS)

    Taffoti Yolong, V.Y.; Woafo, P.

    2007-10-01

    This work deals with the dynamics of a network of piezoelectric micro-beams. The complete synchronization condition for this class of chaotic nonlinear electromechanical systems devices with nearest-neighbor diffusive coupling is studied. The nonlinearities on the device studied here are both on the electrical component and on the mechanical one. The investigation is made for the case of a large number of discrete piezoelectric disks coupled. The problem of chaos synchronization is described and converted into the analysis of stability of the system via its differential equations. We show that the complete synchronization of N identical coupled nonlinear chaotic systems having the shift invariant coupling schemes can be calculated from the synchronization of two of them coupled in both directions. According to analytical, semi-analytical predictions and numerical calculations, the transition boundaries for chaos synchronization state in the coupled system are determined as a function of the increasing number of oscillators. (author)

  6. Ten Thousand Years of Environment Assessment Using Synchrotron Radiation Micro Beam

    Science.gov (United States)

    Shirasawa, K.; Ide-Ektessabi, A.; Koizumi, A.; Azechi, M.

    2003-08-01

    The environment surrounding human has changed through civilization and industrialization, and through these developments, problems including the pollution from heavy metals such as lead and mercury have arisen. In this study, we analyzed major and trace elements in modern and prehistoric teeth by x-ray fluorescence (XRF) analysis using synchrotron radiation micro beam, in order to assess the changes of the environment through the civilization and the industrialization and their affects to the human. It is suggested that teeth accumulate elements in the mineral phase, hydroxiapatite, during their formation, and because there are no significant turnovers, teeth are concerned to be indicators of the environment of the donor. We first analyzed the elements on the surface of tooth from modern individual and tooth from human remains of Jomon period to assess the heavy metal concentration and effect of the diagenesis. The adhering ground elements on the prehistoric teeth showed high amount of Ti, Fe, Mn and other metallic elements.

  7. Nuclear micro-beam analysis of deuterium distribution in carbon fibre composites for controlled fusion devices

    International Nuclear Information System (INIS)

    Petersson, P.; Kreter, A.; Possnert, G.; Rubel, M.

    2010-01-01

    Probes made of carbon fibre composite NB41 were exposed to deuterium plasmas in the TEXTOR tokamak and in a simulator of plasma-wall interactions, PISCES. The aim was to assess the deuterium retention and its lateral and depth distribution. The analysis was performed by means of D( 3 He, p) 4 He and 12 C( 3 He, p) 14 N nuclear reactions analysis using a standard (1 mm spot) and micro-beam (20 μm resolution). The measurements have revealed non uniform distribution of deuterium atoms in micro-regions: differences by a factor of 3 between the maximum and minimum deuterium concentrations. The differences were associated with the orientation and type of fibres for samples exposed in PICSES. For surface structure in the erosion zone of samples exposed to a tokamak plasma the micro-regions were more complex. Depth profiling has indicated migration of fuel into the bulk of materials.

  8. Alignment of dipole magnet in micro-beam line of HIRFL

    International Nuclear Information System (INIS)

    Wang Shaoming; Chen Wenjun; Yang Shengli; Cai Guozhu; Guo Yizhen; Zhou Guangming; Man Kaidi; Song Mingtao

    2010-01-01

    Microbeam irradiation facility is an experiment platform, which can reduce the beam-spot on the irradiated sample to micrometer level, and can accurately locate and count the radioactive particles. It is a powerful research tool for the irradiation material science, irradiation biology, irradiation biomedicine and micro mechanical machining. The microbeam irradiation facility requires the precise work for installation and alignment. These conditions make magnet's change for directions and positions because the location space of dipole magnets in micro-beam line of HIRFL (Heavy Ion Research Facility in Lanzhou) is very small. It is a challenge for the installation and alignment work of magnets. It was solved by transforming coordinates of benchmarks of magnets, which controlled the error of magnet setup within error tolerance range. (authors)

  9. Theoretical and experimental investigation of the triple-differential cross sections for electron-impact ionization of Kr(4p) and Xe(5p) at 1-keV impact energy

    International Nuclear Information System (INIS)

    Rasch, J.; Zitnik, M.; Avaldi, L.; Whelan, C.T.; Stefani, G.; Camilloni, R.; Allan, R.J.; Walters, H.R.

    1997-01-01

    The triple-differential cross sections for the ionization of Kr(4p) and Xe(5p) by a fast electron where the exiting electrons have energies of 20 eV and 1 keV have been measured and compared with distorted-wave Born calculations. Difficulties were encountered when trying to place the relative data on an absolute scale by extrapolation to the optical limit: an extensive study of this normalization process is presented and it is argued that it is not applicable to the heavier atoms considered here, but can be used effectively for helium targets. copyright 1997 The American Physical Society

  10. 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...

  11. Secondary emission coefficient dependence on the angle of incidence of primary electrons on CsI and LiF layers. [0. 9 to 3 keV, mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Shabel' nikova, A E; Yasnopol' skii, N L

    1976-08-01

    The angular dependence was studied of the secondary emission coefficient sigma for CsI and LiF dielectrics which have large sigma in conditions of normal incidence of primary electrons. Measurements were taken down to the angle of 85 deg for energies of primary electrons between 0.9 and 3 keV. In the whole range of angles a nonmonotonic angular dependence sigma is observed. The dependence shows itself particularly clearly for CsI at large energies of primary electrons. Such a behaviour is due to the decrease in the depth of yield of inelastically reflected electrons and to the increase in the inelastic reflection coefficient of the substance.

  12. Analytical formulae for total cross sections for electron scattering by atoms (N, O, F, Ne, P, S, Cl, Ar, As, Se, Br, Kr) between 0.5-10 keV

    International Nuclear Information System (INIS)

    Williart, A.

    2001-01-01

    Analytical formulae for total cross sections for electron scattering by atoms which are close to the noble gases (Ne, Ar and Kr), for electron energies ranging from 0.5 to 10 keV, have been obtained in this study. We have shown, previously, that molecular total cross sections, at these energies, depend on target polarizability and the number of target electrons. A similar behaviour has been supposed for total cross sections of some atoms (N, O, F, P, S, Cl, As, Se and Br). The obtained expression depends on atomic parameters and it is based in some correlation derived from noble gases. The applicability of the formula has been checked by comparison with available data for atomic oxygen. (orig.)

  13. Analytical formulae for total cross sections for electron scattering by atoms (N, O, F, Ne, P, S, Cl, Ar, As, Se, Br, Kr) between 0.5-10 keV

    Energy Technology Data Exchange (ETDEWEB)

    Williart, A. [Univ. Nacional de Educacion a Distancia, Madrid (Spain). Dept. de Fisica de los Materiales; Garcia, G. [Centro de Investigaciones Energeticas, Medioambientales y Tecnologicas, Madrid (Spain)

    2001-10-01

    Analytical formulae for total cross sections for electron scattering by atoms which are close to the noble gases (Ne, Ar and Kr), for electron energies ranging from 0.5 to 10 keV, have been obtained in this study. We have shown, previously, that molecular total cross sections, at these energies, depend on target polarizability and the number of target electrons. A similar behaviour has been supposed for total cross sections of some atoms (N, O, F, P, S, Cl, As, Se and Br). The obtained expression depends on atomic parameters and it is based in some correlation derived from noble gases. The applicability of the formula has been checked by comparison with available data for atomic oxygen. (orig.)

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

    International Nuclear Information System (INIS)

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

    2002-01-01

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

  15. Si(LMM) Auger electron emission from Si alloys by keV Ar/sup +/ ion bombardment, new effect and application

    Energy Technology Data Exchange (ETDEWEB)

    Hiraki, A; Kim, S; Imura, T; Iwami, M [Osaka Univ., Suita (Japan). Faculty of Engineering

    1979-09-01

    Si(LMM) Auger spectra excited by keV ion bombardment were studied in Si alloyed with several elements (Au, Cu, Pd, Ni, C, and H). The spectra differed completely from those of pure Si. The main characteristics are (1) the spectra are composed of two well-separated peaks (88 and 92 eV) called the atomic-like peak (88 eV) and the bulk-like peak (92 eV); and (2) the atomic-like peak is enhanced with respect to the bulk-like peak, and this enhancement becomes more obvious as the concentration of partner elements of the alloys are increased. The possible application of the present phenomena is proposed as a technique for detecting the homogeneity of Si alloy films in the three-dimensional sense - as an example, the three-dimensional distribution of hydrogen in hydrogenated amorphous silicon (a-Si-H).

  16. LabVIEW control software for scanning micro-beam X-ray fluorescence spectrometer.

    Science.gov (United States)

    Wrobel, Pawel; Czyzycki, Mateusz; Furman, Leszek; Kolasinski, Krzysztof; Lankosz, Marek; Mrenca, Alina; Samek, Lucyna; Wegrzynek, Dariusz

    2012-05-15

    Confocal micro-beam X-ray fluorescence microscope was constructed. The system was assembled from commercially available components - a low power X-ray tube source, polycapillary X-ray optics and silicon drift detector - controlled by an in-house developed LabVIEW software. A video camera coupled to optical microscope was utilized to display the area excited by X-ray beam. The camera image calibration and scan area definition software were also based entirely on LabVIEW code. Presently, the main area of application of the newly constructed spectrometer is 2-dimensional mapping of element distribution in environmental, biological and geological samples with micrometer spatial resolution. The hardware and the developed software can already handle volumetric 3-D confocal scans. In this work, a front panel graphical user interface as well as communication protocols between hardware components were described. Two applications of the spectrometer, to homogeneity testing of titanium layers and to imaging of various types of grains in air particulate matter collected on membrane filters, were presented. Copyright © 2012 Elsevier B.V. All rights reserved.

  17. Evaluation of support loss in micro-beam resonators: A revisit

    Science.gov (United States)

    Chen, S. Y.; Liu, J. Z.; Guo, F. L.

    2017-12-01

    This paper presents an analytical study on evaluation of support loss in micromechanical resonators undergoing in-plane flexural vibrations. Two-dimensional elastic wave theory is used to determine the energy transmission from the vibrating resonator to the support. Fourier transform and Green's function technique are adopted to solve the problem of wave motions on the surface of the support excited by the forces transmitted by the resonator onto the support. Analytical expressions of support loss in terms of quality factor, taking into account distributed normal stress and shear stress in the attachment region, and coupling between the normal stress and shear stress as well as material disparity between the support and the resonator, have been derived. Effects of geometry of micro-beam resonators, and material dissimilarity between support and resonator on support loss are examined. Numerical results show that 'harder resonator' and 'softer support' combination leads to larger support loss. In addition, the Perfectly Matched Layer (PML) numerical simulation technique is employed for validation of the proposed analytical model. Comparing with results of quality factor obtained by PML technique, we find that the present model agrees well with the results of PML technique and the pure-shear model overestimates support loss noticeably, especially for resonators with small aspect ratio and large material dissimilarity between the support and resonator.

  18. Dynamic pull-in instability of geometrically nonlinear actuated micro-beams based on the modified couple stress theory

    Directory of Open Access Journals (Sweden)

    Hamid M. Sedighi

    Full Text Available This paper investigates the dynamic pull-in instability of vibrating micro-beams undergoing large deflection under electrosatically actuation. The governing equation of motion is derived based on the modified couple stress theory. Homotopy Perturbation Method is employed to produce the high accuracy approximate solution as well as the second-order frequency- amplitude relationship. The nonlinear governing equation of micro beam vibrations predeformed by an electric field includes both even and odd nonlinearities. The influences of basic non-dimensional parameters on the pull-in instability as well as the natural frequency are studied. It is demonstrated that two terms in series expansions are sufficient to produce high accuracy solution of the micro-structure. The accuracy of proposed asymptotic approach is validated via numerical results. The phase portrait of the system exhibits periodic and homoclinic orbits.

  19. X-ray micro-beam characterization of a small pixel spectroscopic CdTe detector

    Science.gov (United States)

    Veale, M. C.; Bell, S. J.; Seller, P.; Wilson, M. D.; Kachkanov, V.

    2012-07-01

    A small pixel, spectroscopic, CdTe detector has been developed at the Rutherford Appleton Laboratory (RAL) for X-ray imaging applications. The detector consists of 80 × 80 pixels on a 250 μm pitch with 50 μm inter-pixel spacing. Measurements with an 241Am γ-source demonstrated that 96% of all pixels have a FWHM of better than 1 keV while the majority of the remaining pixels have FWHM of less than 4 keV. Using the Diamond Light Source synchrotron, a 10 μm collimated beam of monochromatic 20 keV X-rays has been used to map the spatial variation in the detector response and the effects of charge sharing corrections on detector efficiency and resolution. The mapping measurements revealed the presence of inclusions in the detector and quantified their effect on the spectroscopic resolution of pixels.

  20. Micro-beam X-ray fluorescence and absorption imaging techniques at the IAEA Laboratories

    International Nuclear Information System (INIS)

    Wegrzynek, Dariusz; Markowicz, A.; Bamford, S.; Chinea-Cano, E.; Bogovac, M.

    2005-01-01

    X-ray tube based, micro-beam X-ray fluorescence scanning spectrometer has been equipped with two energy dispersive X-ray detectors. The two-detector configuration allows for simultaneous collection of X-ray fluorescence (XRF) and transmitted X-ray beam signals with a spatial resolution in the range of 10-50 μm, depending on the X-ray focussing element in use. The XRF signal is collected with a standard, liquid nitrogen cooled Si(Li) detector. The X-ray beam transmitted through the sample is acquired with a thermoelectrically cooled, silicon drift (SD) detector. The data acquisition is carried out in a fully automatic way under control of the SPECTOR-LOCATOR software. The software controls the scanning procedure and X-ray spectra acquisition during the scan. The energy dispersive X-ray spectra collected at every 'pixel' are stored for off-line processing. For selected regions of interest (ROI's), the element maps are constructed and displayed on-line. The spectrometer has been used for mapping elemental distributions and for performing 2D- and 3D-tomograpic imaging of minute objects in X-ray absorption and in X-ray fluorescence mode. A unique feature of the described system is simultaneous utilization of the two detectors, Si(Li) and SD, which adds new options for quantitative analysis and data interpretation. Examples of elemental mapping and 3D tomographic imaging as well as the advanced features of the SPECTOR-LOCATOR measurement control and data acquisition software are presented in this work

  1. SU-F-T-672: A Novel Kernel-Based Dose Engine for KeV Photon Beams

    Energy Technology Data Exchange (ETDEWEB)

    Reinhart, M; Fast, M F; Nill, S; Oelfke, U [The Institute of Cancer Research and The Royal Marsden NHS Foundation Trust, London (United Kingdom)

    2016-06-15

    Purpose: Mimicking state-of-the-art patient radiotherapy with high precision irradiators for small animals allows advanced dose-effect studies and radiobiological investigations. One example is the implementation of pre-clinical IMRT-like irradiations, which requires the development of inverse planning for keV photon beams. As a first step, we present a novel kernel-based dose calculation engine for keV x-rays with explicit consideration of energy and material dependencies. Methods: We follow a superposition-convolution approach adapted to keV x-rays, based on previously published work on micro-beam therapy. In small animal radiotherapy, we assume local energy deposition at the photon interaction point, since the electron ranges in tissue are of the same order of magnitude as the voxel size. This allows us to use photon-only kernel sets generated by MC simulations, which are pre-calculated for six energy windows and ten base materials. We validate our stand-alone dose engine against Geant4 MC simulations for various beam configurations in water, slab phantoms with bone and lung inserts, and on a mouse CT with (0.275mm)3 voxels. Results: We observe good agreement for all cases. For field sizes of 1mm{sup 2} to 1cm{sup 2} in water, the depth dose curves agree within 1% (mean), with the largest deviations in the first voxel (4%) and at depths>5cm (<2.5%). The out-of-field doses at 1cm depth agree within 8% (mean) for all but the smallest field size. In slab geometries, the mean agreement was within 3%, with maximum deviations of 8% at water-bone interfaces. The γ-index (1mm/1%) passing rate for a single-field mouse irradiation is 71%. Conclusion: The presented dose engine yields an accurate representation of keV-photon doses suitable for inverse treatment planning for IMRT. It has the potential to become a significantly faster yet sufficiently accurate alternative to full MC simulations. Further investigations will focus on energy sampling as well as calculation

  2. Effect of the sample annealing temperature and sample crystallographic orientation on the charge kinetics of MgO single crystals subjected to keV electron irradiation.

    Science.gov (United States)

    Boughariou, A; Damamme, G; Kallel, A

    2015-04-01

    This paper focuses on the effect of sample annealing temperature and crystallographic orientation on the secondary electron yield of MgO during charging by a defocused electron beam irradiation. The experimental results show that there are two regimes during the charging process that are better identified by plotting the logarithm of the secondary electron emission yield, lnσ, as function of the total trapped charge in the material QT. The impact of the annealing temperature and crystallographic orientation on the evolution of lnσ is presented here. The slope of the asymptotic regime of the curve lnσ as function of QT, expressed in cm(2) per trapped charge, is probably linked to the elementary cross section of electron-hole recombination, σhole, which controls the trapping evolution in the reach of the stationary flow regime. © 2014 The Authors Journal of Microscopy © 2014 Royal Microscopical Society.

  3. THE DEVELOPMENT OF A SUPER-STABLE DATUM POINT FOR MONITORING THE ENERGY SCALE OF ELECTRON SPECTROMETERS IN THE ENERGY RANGE UP TO 20 keV

    Czech Academy of Sciences Publication Activity Database

    Vénos, Drahoslav; Zbořil, Miroslav; Kašpar, Jaromír; Dragoun, Otokar; Bonn, J.; Kovalík, Alojz; Lebeda, Ondřej; Lebedev, N. A.; Ryšavý, Miloš; Schlosser, K.; Špalek, Antonín; Weinheimer, C.

    2010-01-01

    Roč. 53, č. 3 (2010), s. 305-312 ISSN 0543-1972 R&D Projects: GA ČR GA202/06/0002; GA MŠk LA318; GA MŠk LC07050; GA MŠk LA08002 Institutional research plan: CEZ:AV0Z10480505 Keywords : nuclear transition energy * conversion electrons * electron spectrometer Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.154, year: 2010

  4. Coulomb focusing and path'' interference of autoionizing electrons produced in 10 keV He sup + + He collisions

    Energy Technology Data Exchange (ETDEWEB)

    Swenson, J.K. (Lawrence Livermore National Lab., CA (USA)); Burgdoerfer, J. (Tennessee Univ., Knoxville, TN (USA)); Meyer, F.W.; Havener, C.C.; Gregory, D.C.; Stolterfoht, N. (Oak Ridge National Lab., TN (USA))

    1991-03-13

    Autoionizing electrons emitted following low energy ion-atom collisions may scatter significantly from the receding spectator ion's attractive Coulomb field. In such cases the observed electron intensity is focused'' in the direction of the scattering ion as a result of the effective compression of the emission solid angle. In addition, interference may occur between trajectories, corresponding to electrons scattering around opposite sides of the ion, which lead to the same final laboratory electron energy and emission angle. This Coulomb path'' interference mechanism manifests itself in the uncharacteristically rapid angular dependence of the He target 2s{sup 2} {sup 1}S autoionizing state measured near 0{degree} following low energy He{sup +} + He collisions. A classical trajectory model for Coulomb focusing is presented and a semi-classical approximation is used to model the Coulomb path'' interference mechanism. In this description we account for the evolution of the phase of the autoionizing state until its decay and the path dependence of the amplitude of the emitted electron following decay of the autoionizing state. Calculated model lineshapes, which include contributions from adjacent overlapping resonances, reproduce quite well the angular dependence observed in the data near 0{degree}. 14 refs., 7 figs.

  5. Autoionisation of N5+ (nln'l') with n = 2,3,4 and n' >= n measured by electron spectrometry in collisions of N7+ with He and H2, at 4.9 keV amu-1

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.; Dousson, S.; Hitz, D.

    1984-01-01

    a spectroscopic investigation of electrons coming from autoionising states N 5+ (nln'l'), with n=2,3,4 and n' >= n, of the fast ion has been made at 11.6 0 and 4.9 keV amu -1 . Only exothermic reactions are observed. It is shown that the ionisation potential of the target has a strong influence on the more probable values of n and n'. In N 7+ -He collisions, the n=3, n'=3 configurations are the more excited. In N 7+ -H 2 , the capture process is less selective since n=3, n' > 3 and also n=4, n' >= 4 configurations are strongly populated. In all these cases, the residual N 6+ ion is left in an excited state (n=2 or 3). The n=2, n' > 2 excitation probability is found to be much smaller for the two collisional systems. (author)

  6. An analytical expression for electron elastic scattering cross section from atoms and molecules in 1.0 keV to 1.0 MeV energy range

    Energy Technology Data Exchange (ETDEWEB)

    Yalcin, S. [Education Faculty, Kastamonu University, 37200 Kastamonu (Turkey)]. E-mail: yalcin@gazi.edu.tr; Gurler, O. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Gultekin, A. [Physics Department, Faculty of Arts and Sciences, Uludag University, Gorukle Campus, 16059 Bursa (Turkey); Gundogdu, O. [School of Engineering, University of Surrey, Guildford, GU2 7XH (United Kingdom)]. E-mail: o.gundogdu@surrey.ac.uk

    2006-07-31

    In this Letter, an expression is presented to calculate elastic scattering cross sections for incident electrons as a function of both energy and atomic number in the energy range between 1 keV and 1 MeV for materials with effective atomic number between 3 and 18. The expression we present has a rather simple analytical form which gives accurate results that are in very good agreement with the results calculated by a relativistic partial-wave expansion method. Hence, this equation can be employed accurately and efficiently in a continuous manner, without the need to go through rather large look-up tables, thus making the whole process quick, efficient and removing possible computational errors that may arise from the efforts of interpolation.

  7. An analytical expression for electron elastic scattering cross section from atoms and molecules in 1.0 keV to 1.0 MeV energy range

    International Nuclear Information System (INIS)

    Yalcin, S.; Gurler, O.; Gultekin, A.; Gundogdu, O.

    2006-01-01

    In this Letter, an expression is presented to calculate elastic scattering cross sections for incident electrons as a function of both energy and atomic number in the energy range between 1 keV and 1 MeV for materials with effective atomic number between 3 and 18. The expression we present has a rather simple analytical form which gives accurate results that are in very good agreement with the results calculated by a relativistic partial-wave expansion method. Hence, this equation can be employed accurately and efficiently in a continuous manner, without the need to go through rather large look-up tables, thus making the whole process quick, efficient and removing possible computational errors that may arise from the efforts of interpolation

  8. 40 keV atomic resolution TEM

    International Nuclear Information System (INIS)

    Bell, David C.; Russo, Christopher J.; Kolmykov, Dmitry V.

    2012-01-01

    Here we present the first atomic resolution TEM imaging at 40 keV using an aberration-corrected, monochromated source TEM. Low-voltage High-Resolution Electron Microscopy (LVHREM) has several advantages, including increased cross-sections for inelastic and elastic scattering, increased contrast per electron and improved spectroscopy efficiency, decreased delocalization effects and reduced knock-on damage. Together, these often improve the contrast to damage ratio obtained on a large class of samples. Third-order aberration correction now allows us to operate the TEM at low energies while retaining atomic resolution, which was previously impossible. At low voltage the major limitation to resolution becomes the chromatic aberration limit. We show that using a source monochromator we are able to reduce the effect of chromatic aberration and achieve a usable high-resolution limit at 40 keV to less than 1 Å. We show various materials' examples of the application of the technique to image graphene and silicon, and compare atomic resolution images with electron multislice simulations. -- Highlights: ► We present the first atomic resolution images recorded at 40 keV using an aberration-corrected, monochromated TEM. ► We show information transfer measured to better than 1 Å. ► At 40 keV an aberration-corrected monochromated TEM is limited by fifth-order spherical aberration. ► We show that using a monochromator the effect of chromatic aberration is reduced to enable high resolution imaging. ► Low voltage high resolution electron microscopy will be beneficial for imaging the organic/inorganic materials interface.

  9. Absolute total and one- and two-electron transfer cross sections for Arq+ (8≤q≤16) on He and H2 at 2.3q keV

    International Nuclear Information System (INIS)

    Vancura, J.; Marchetti, V.J.; Perotti, J.J.; Kostroun, V.O.

    1993-01-01

    Absolute values for the total and one- and two-electron transfer cross sections for Ar q+ ions (8≤q≤16) colliding with helium and molecular hydrogen at 2.3q keV laboratory energy were measured by the growth-rate method. The He and H 2 total cross sections as a function of Ar-projectile L-shell occupation number increase monotonically from Ar 8+ , 2p shell full, to Ar 16+ , 2s shell empty. The H 2 one-electron capture cross section scales approximately as [E IP (He)/E IP (H 2 )] 2 times the corresponding He cross section, but the shapes of the two cross sections differ in detail. The Ar q+ ions were produced by the Cornell superconducting-solenoid, cryogenic electron-beam ion source (CEBIS) and extracted at 2.3 kV. Selected charge states traversed a gas cell, after which they were detected and charge-state analyzed by the energy-retardation method and by a π/ √2 cylindrical electrostatic analyzer. The target-gas pressure in the cell was measured directly by the orifice-flow method used for absolute-pressure gauge calibration. The overall error in the Ar q+ on H 2 cross-section measurements is ±10%, and ±15% in the He measurements

  10. Measurement of relative depth-dose distribution in radiochromic film dosimeters irradiated with 43-70 keV electron beam for industrial application

    Science.gov (United States)

    Matsui, Shinjiro; Hattori, Takeaki; Nonaka, Takashi; Watanabe, Yuki; Morita, Ippei; Kondo, Junichi; Ishikawa, Masayoshi; Mori, Yoshitaka

    2018-05-01

    The relative dose in a layer, which is thinner than the thickness of the dosimeter is evaluated using simulated depth-dose distributions, and the measured responses of dosimeters with acceleration voltages from 43 to 70 kV, via ultra-low-energy electron beam (ULEB) irradiation. By stacking thin film dosimeters, we confirmed that the simulated depth-dose distributions coincided with the measured depth-dose curve within the measurement uncertainty (k = 2). Using the measurement dose of the 47 μm dosimeter and the simulated depth-dose distribution, the dose of 11 μm dosimeters in the surface was evaluated within the measurement uncertainty (k = 2). We also verified the effectiveness of this method for a thinner layer by changing the acceleration voltage of the irradiation source. We evaluated the relative dose for an adjusted depth of energy deposition from 4.4 μm to 22.8 μm. As a result, this method was found to be effective for a thickness, which is less than the thickness of the dosimeter. When irradiation conditions are well known with accuracy, using the confirmed relative depth-dose distributions across any dosimeter thickness range, a dose evaluation, in several μm steps will possibly improve the design of industrial ULEB processes.

  11. Studies towards the understanding of the effects of ionizing radiations at the molecular scale (20-150 keV H+/H + He Collisions; dissociative electron attachment to water)

    International Nuclear Information System (INIS)

    Coupier, B.

    2005-11-01

    This work comes within the scope of recent studies towards a better understanding of the effect of ionizing radiation at the molecular scale on biological systems. It is composed of two parts. The first one presents a new set of coincidence measurements of cross sections for the impact of protons or hydrogen atoms on helium in the energy range 20-150 keV of interest for the radiation biology. It is an archetypical system of interest for the theoreticians and there exists only a few studies on the impact of hydrogen atoms on helium. This study with helium was also motivated for the sake of performing a general test of functioning of the apparatus before investigating more complicated systems. Similar studies were then performed by replacing helium with water and biological molecules of relevance (Uracil, Thymine...) as target. This constitutes a study of direct effects of fast ionizing radiations on molecules of biological interest. The second part of the thesis deals with another type of ionizing radiations which can be seen as indirect effects of the first fast ionizing radiations studied in the first part. Low energy electrons emission in the energy range 1 to 16 eV follows the bombardment of the matter by swift protons/hydrogen atoms; these electrons have in turn an ionizing influence on the environment. A review of the dissociative electron attachment to water was undertaken motivated by the existing discrepancies between old studies on the same subject. A special attention was given to the problem of high energy kinetic ion discrimination in the trochoidal monochromator used for this work. (author)

  12. Observation of atomic oxygen O(1S) green-line emission in the summer polar upper mesosphere associated with high-energy (≥30 keV) electron precipitation during high-speed solar wind streams

    Science.gov (United States)

    Lee, Young-Sook; Kwak, Young-Sil; Kim, Kyung-Chan; Solheim, Brian; Lee, Regina; Lee, Jaejin

    2017-01-01

    The auroral green-line emission at 557.7 nm wavelength as arising from the atomic oxygen O(1S → 1D) transition typically peaks at an altitude of 100 km specifically in the nightside oval, induced by auroral electrons within an energy range of 100 eV-30 keV. Intense aurora is known as being suppressed by sunlight in summer daytime but usually occurs in low electrical background conductivity. However, in the present study in summer (July) sunlit condition, enhancements of O(1S) emission rates observed by using the Wind Imaging Interferometer/UARS were frequently observed at low altitudes below 90 km, where ice particles are created initially as subvisible and detected as polar mesosphere summer echoes, emerging to be an optical phenomenon of polar mesospheric clouds. The intense O(1S) emission occurring in summer exceeds those occurring in the daytime in other seasons both in occurrence and in intensity, frequently accompanied by occurrences of supersonic neutral velocity (300-1500 m s-1). In the mesosphere, ion motion is controlled by electric field and the momentum is transferred to neutrals. The intense O(1S) emission is well associated with high-energy electron precipitation as observed during an event of high-speed solar wind streams. Meanwhile, since the minimum occurrences of O(1S) emission and supersonic velocity are maintained even in the low precipitation flux, the mechanism responsible is not only related to high-energy electron precipitation but also presumably to the local conditions, including the composition of meteoric-charged ice particles and charge separation expected in extremely low temperatures (<150 K).

  13. Studies towards the understanding of the effects of ionizing radiations at the molecular scale (20-150 keV H{sup +}/H + He Collisions; dissociative electron attachment to water)

    Energy Technology Data Exchange (ETDEWEB)

    Coupier, B

    2005-11-15

    This work comes within the scope of recent studies towards a better understanding of the effect of ionizing radiation at the molecular scale on biological systems. It is composed of two parts. The first one presents a new set of coincidence measurements of cross sections for the impact of protons or hydrogen atoms on helium in the energy range 20-150 keV of interest for the radiation biology. It is an archetypical system of interest for the theoreticians and there exists only a few studies on the impact of hydrogen atoms on helium. This study with helium was also motivated for the sake of performing a general test of functioning of the apparatus before investigating more complicated systems. Similar studies were then performed by replacing helium with water and biological molecules of relevance (Uracil, Thymine...) as target. This constitutes a study of direct effects of fast ionizing radiations on molecules of biological interest. The second part of the thesis deals with another type of ionizing radiations which can be seen as indirect effects of the first fast ionizing radiations studied in the first part. Low energy electrons emission in the energy range 1 to 16 eV follows the bombardment of the matter by swift protons/hydrogen atoms; these electrons have in turn an ionizing influence on the environment. A review of the dissociative electron attachment to water was undertaken motivated by the existing discrepancies between old studies on the same subject. A special attention was given to the problem of high energy kinetic ion discrimination in the trochoidal monochromator used for this work. (author)

  14. Pre Design of Beam Parameter Control System for Electron Beam Machine (EBM) 350 keV/10 mA in the Center for Accelerator and Material Process Technology - BATAN Yogyakarta

    International Nuclear Information System (INIS)

    Sutanto

    2009-01-01

    Pre design of beam parameter control system for Electron Beam Machine (EBM) 350 keV/10 mA had an objective to find a control system algorithm for EBM in The Center For Accelerator and Material Process Technology (Pusat Teknologi dan Proses Bahan/PTAPB) - BATAN Yogyakarta. The design was based on the beam parameter model of EBM. The model shown a relationship between the dose parameter setting and the beam energy setting which it was being a problem in setting the beam parameters.The control system algorithm was found by getting compensator equations from the beam parameter model of EBM. The equations would omit the relation between the radiation dose parameter and beam energy parameter, so that the parameters could be adjusted easily. The result of the control system algorithm examine based on simulation shown that the setting of beam parameter value could be done by giving the accelerating voltage value and the filament current value as the operator had determined the value. The value of radiation dose and beam energy would be adjusted as its function of the filament current value and the accelerating voltage value. (author)

  15. The influence of microstructure on the cyclic deformation and damage of copper and an oxide dispersion strengthened steel studied via in-situ micro-beam bending

    Energy Technology Data Exchange (ETDEWEB)

    Howard, C., E-mail: cam7745@berkeley.edu [University of California, 2111A Etcheverry Hall, Berkeley, CA 94720-1730 (United States); Fritz, R.; Alfreider, M.; Kiener, D. [Department of Materials Physics, Montanuniversität Leoben, A-8700, Leoben (Austria); Hosemann, P. [University of California, 2111A Etcheverry Hall, Berkeley, CA 94720-1730 (United States)

    2017-02-27

    Service materials are often designed for strength, ductility, or toughness, but neglect the effects of cyclic time-variable loads ultimately leading to macroscopic mechanical failure. Fatigue originates as local plasticity that can first only be observed on the micro scale at defects serving as stress concentrators such as inclusions or grain boundaries. Thus, a recently developed technique to perform in-situ observation of micro scale bending fatigue experiments was applied. Micro-beams fabricated from copper, single grained and ultrafine grained (ufg), and an oxide dispersion strengthened (ODS) steel were subject to cyclic deformation and subsequent damage. The elastic stiffness, yield strength, dissipated energy, and maximum stress were measured as a function of cycle number and plastic strain amplitude. From these properties, cyclic stress-strain curves were developed. Initial pronounced monotonic hardening and an increasing Bauschinger effect were observed in all samples with increasing strain amplitude. Cyclic stability was maintained until plastic strain amplitudes reached a critical value. At this point, dramatic cyclic softening and microcracking occurred. The critical strain amplitude was found to be approximately 5.4×10{sup −3} for the copper with a refined grain structure and 1.2×10{sup −2} for the steel specimen. Grain rotation and noticeable changes in sub-grain structure were evident in the ufg copper after a critical strain amplitude of ε{sub a}=8.3×10{sup −3}. In-situ micro fatigue bending couples the cyclic evolution of bulk mechanical properties measurements with real-time electron microscopy analysis techniques of damage and failure mechanisms, which renders it a powerful method for developing novel fatigue resistant materials.

  16. 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...

  17. Beta decay anomalies and the 17-keV conundrum

    International Nuclear Information System (INIS)

    Hime, A.

    1993-01-01

    Recent developments in pursuance of the 17-keV neutrino are reviewed. Several different experiments found anomalies in β decay spectra which were consistently interpreted as evidence for a heavy neutrino. On the other hand, recent null results definitively rule out the existence of a 17-keV neutrino, as well as escaping criticisms applicable to earlier experiments. While missing links remain, it seems that any strong evidence for a 17-keV neutrino has vanished. Specifically, the anomalies observed in 35 S and 63 Ni spectra at Oxford can be reinterpreted in terms of electron scattering effects. In addition, the discrepancy amongst internal bremsstrahlung measurements has an instrumental origin, and recent results disfavour a 17-keV neutrino. Anomalies persist in the low energy region of the tritium spectrum which deserve further investigation

  18. Probing Defects in a Small Pixellated CdTe Sensor Using an Inclined Mono Energetic X-Ray Micro Beam

    Science.gov (United States)

    Fröjdh, Erik; Fröjdh, C.; Gimenez, E. N.; Krapohl, D.; Maneuski, D.; Norlin, B.; O'Shea, V.; Wilhelm, H.; Tartoni, N.; Thungström, G.; Zain, R. M.

    2013-08-01

    High quantum efficiency is important in X-ray imaging applications. This means using high-Z sensor materials. Unfortunately many of these materials suffer from defects that cause non-ideal charge transport. In order to increase the understanding of these defects, we have mapped the 3D response of a number of defects in two 1 mm thick CdTe sensors with different pixel sizes (55 μm and 110 μm) using a monoenergetic microbeam at 79 keV. The sensors were bump bonded to Timepix read out chips. Data was collected in photon counting as well as time-over-threshold mode. The time-over-threshold mode is a very powerful tool to investigate charge transport properties and fluorescence in pixellated detectors since the signal from the charge that each photon deposits in each pixel can be analyzed. Results show distorted electrical field around the defects, indications of excess leakage current and large differences in behavior between electron collection and hole collection mode. The experiments were carried out on the Extreme Conditions Beamline I15 at Diamond Light Source.

  19. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Science.gov (United States)

    Zhao, Jifei; Lu, Xiangyang; Zhou, Kui; Yang, Ziqin; Yang, Deyu; Luo, Xing; Tan, Weiwei; Yang, Yujia

    2016-06-01

    As an important electron source, Micro-Pulse electron Gun (MPG) which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR), Free Electron Laser (FEL). The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY) curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC) effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  20. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Jifei; Lu, Xiangyang, E-mail: xylu@pku.edu.cn; Yang, Ziqin; Yang, Deyu; Tan, Weiwei; Yang, Yujia [Institute of Heavy Ion Physics, School of Physics, Peking University, Beijing, 100871 (China); Zhou, Kui; Luo, Xing [Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900 (China)

    2016-06-15

    As an important electron source, Micro-Pulse electron Gun (MPG) which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR), Free Electron Laser (FEL). The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY) curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC) effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  1. Theoretical analysis and simulation of the influence of self-bunching effects and longitudinal space charge effects on the propagation of keV electron bunch produced by a novel S-band Micro-Pulse electron Gun

    Directory of Open Access Journals (Sweden)

    Jifei Zhao

    2016-06-01

    Full Text Available As an important electron source, Micro-Pulse electron Gun (MPG which is qualified for producing high average current, short pulse, low emittance electron bunches steadily holds promise to use as an electron source of Coherent Smith-Purcell Radiation (CSPR, Free Electron Laser (FEL. The stable output of S-band MPG has been achieved in many labs. To establish reliable foundation for the future application of it, the propagation of picosecond electron bunch produced by MPG should be studied in detail. In this article, the MPG which was working on the rising stage of total effective Secondary Electron Yield (SEY curve was introduced. The self-bunching mechanism was discussed in depth both in the multipacting amplifying state and the steady working state. The bunch length broadening induced by the longitudinal space-charge (SC effects was investigated by different theoretical models in different regions. The 2D PIC codes MAGIC and beam dynamic codes TraceWin simulations were also performed in the propagation. The result shows an excellent agreement between the simulation and the theoretical analysis for bunch length evolution.

  2. A model for Simpson's 17 keV neutrino

    International Nuclear Information System (INIS)

    Rajpoot, S.

    1992-01-01

    Recent studies of β-decay spectra seem to confirm Simpson's earlier findings that the electron neutrinos contain a small (1%) admixture of a 17 keV Dirac neutrino. In this paper an unconventional model with SU(2) L x SU(2) R x U(1) B-1 gauge interactions is presented in which all neutrinos are Dirac particles. Electron and muon neutrinos acquire seesaw Dirac masses of order 10 -3 eV for the MSW solution for the solar neutrino problem. The τ neutrino is identified as Simpson's 17 keV neutrino. Constraints coming from cosmology and particle physics are shown to be satisfied

  3. 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

  4. 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.

  5. Nucleosynthesis confronts an unstable inert 17 keV state

    International Nuclear Information System (INIS)

    Enqvist, K.; Kainulainen, K.; Thomson, M.

    1991-01-01

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

  6. Elastic and inelastic processes in H+ + CH2 collisions below the 1.5 keV regime

    International Nuclear Information System (INIS)

    Suno, Hiroya; Rai, Sachchida N.; Liebermann, Heinz-Peter; Buenker, Robert J.; Kimura, Mineo; Janev, R.K.

    2005-01-01

    Electron capture and direct elastic scattering in collisions of H + ions with CH 2 molecules between 0.5 and 1.5 keV are theoretically investigated. A molecular representation is adopted within a fully quantum-mechanical approach. Differential cross sections (DCSs) for elastic scattering and electron capture are calculated at 1.5 keV and 0.5 keV for different molecular orientations. Our results indicate that electron capture dynamics and corresponding electron-capture cross sections depend substantially on the molecular orientation, thus revealing a strong steric effect. (author)

  7. Experiments on secondary ion emission with multicharged keV ion bombardement

    International Nuclear Information System (INIS)

    Della Negra, S.; Depauw, J.; Joret, H.; Le Beyec, Y.; Schweikert, E.A.

    1987-01-01

    An electron cyclotron resonance ion source was used to study the influence of the incident charge state of keV ions on secondary ion emission. The experiments were run with 18 keV Arn+ (1 < n < 11) beams produced by a minimafios source. Various types of targets were bombarded by the ion beam and the sputtered ionized species were identified by time of flight mass spectrometry. The experimental arrangement is detailed and preliminary results are indicated

  8. Neutron resonance parameters of 96Zr below 100 keV

    International Nuclear Information System (INIS)

    Musgrove, A.R.D.

    1977-08-01

    Transmission data taken at the 80 m station of the Oak Ridge Electron Linear Accelerator have provided resonance parameters for 96 Zr to 100 keV. The average level spacing and neutron strength function for s-wave neutrons were as follows: = 8 +- 2 keV and S 0 = (0.21 +- 0.10) x 10 -4 . The average p-wave neutron strength function was S 1 = (7.4 +- 2.0) x 10 -4 . (Author)

  9. Power supply for the LBL 40 keV neutral beam source

    International Nuclear Information System (INIS)

    Baker, W.R.; Fitzgerald, M.L.; Honey, V.J.

    1975-11-01

    A 20 keV, 50 Amp, 10 millisec pulse D 0 Neutral Beam Source at the Lawrence Berkeley Laboratory that serves as the prototype for 12 similar sources now in operation on the 2XIIB Mirror Machine at the Lawrence Livermore Laboratory has been recently upgraded to operate at 40 keV. The system of electronically regulated and controlled power supplies that drive the Source is described

  10. DC dynamic pull-in predictions for a generalized clamped–clamped micro-beam based on a continuous model and bifurcation analysis

    International Nuclear Information System (INIS)

    Chao, Paul C-P; Chiu, C W; Liu, Tsu-Hsien

    2008-01-01

    This study is devoted to providing precise predictions of the dc dynamic pull-in voltages of a clamped–clamped micro-beam based on a continuous model. A pull-in phenomenon occurs when the electrostatic force on the micro-beam exceeds the elastic restoring force exerted by beam deformation, leading to contact between the actuated beam and bottom electrode. DC dynamic pull-in means that an instantaneous application of the voltage (a step function such as voltage) is applied. To derive the pull-in voltage, a dynamic model in partial differential equations is established based on the equilibrium among beam flexibility, inertia, residual stress, squeeze film, distributed electrostatic forces and its electrical field fringing effects. The method of Galerkin decomposition is then employed to convert the established system equations into reduced discrete modal equations. Considering lower-order modes and approximating the beam deflection by a different order series, bifurcation based on phase portraits is conducted to derive static and dynamic pull-in voltages. It is found that the static pull-in phenomenon follows dynamic instabilities, and the dc dynamic pull-in voltage is around 91–92% of the static counterpart. However, the derived dynamic pull-in voltage is found to be dependent on the varied beam parameters, different from a fixed predicted value derived in past works, where only lumped models are assumed. Furthermore, accurate closed-form predictions are provided for non-narrow beams. The predictions are finally validated by finite element analysis and available experimental data

  11. Hard alpha-keratin degradation inside a tissue under high flux X-ray synchrotron micro-beam: a multi-scale time-resolved study.

    Science.gov (United States)

    Leccia, Emilie; Gourrier, Aurélien; Doucet, Jean; Briki, Fatma

    2010-04-01

    X-rays interact strongly with biological organisms. Synchrotron radiation sources deliver very intense X-ray photon fluxes within micro- or submicro cross-section beams, resulting in doses larger than the MGy. The relevance of synchrotron radiation analyses of biological materials is therefore questionable since such doses, million times higher than the ones used in radiotherapy, can cause huge damages in tissues, with regard to not only DNA, but also proteic and lipid organizations. Very few data concerning the effect of very high X-ray doses in tissues are available in the literature. We present here an analysis of the structural phenomena which occur when the model tissue of human hair is irradiated by a synchrotron X-ray micro-beam. The choice of hair is supported by its hierarchical and partially ordered keratin structure which can be analysed inside the tissue by X-ray diffraction. To assess the damages caused by hard X-ray micro-beams (1 microm(2) cross-section), short exposure time scattering SAXS/WAXS patterns have been recorded at beamline ID13 (ESRF) after various irradiation times. Various modifications of the scattering patterns are observed, they provide fine insight of the radiation damages at various hierarchical levels and also unexpectedly provide information about the stability of the various hierarchical structural levels. It appears that the molecular level, i.e. the alpha helices which are stabilized by hydrogen bonds and the alpha-helical coiled coils which are stabilized by hydrophobic interactions, is more sensitive to radiation than the supramolecular architecture of the keratin filament and the filament packing within the keratin associated proteins matrix, which is stabilized by disulphide bonds. (c) 2009 Elsevier Inc. All rights reserved.

  12. Accurate electrostatic and van der Waals pull-in prediction for fully clamped nano/micro-beams using linear universal graphs of pull-in instability

    Science.gov (United States)

    Tahani, Masoud; Askari, Amir R.

    2014-09-01

    In spite of the fact that pull-in instability of electrically actuated nano/micro-beams has been investigated by many researchers to date, no explicit formula has been presented yet which can predict pull-in voltage based on a geometrically non-linear and distributed parameter model. The objective of present paper is to introduce a simple and accurate formula to predict this value for a fully clamped electrostatically actuated nano/micro-beam. To this end, a non-linear Euler-Bernoulli beam model is employed, which accounts for the axial residual stress, geometric non-linearity of mid-plane stretching, distributed electrostatic force and the van der Waals (vdW) attraction. The non-linear boundary value governing equation of equilibrium is non-dimensionalized and solved iteratively through single-term Galerkin based reduced order model (ROM). The solutions are validated thorough direct comparison with experimental and other existing results reported in previous studies. Pull-in instability under electrical and vdW loads are also investigated using universal graphs. Based on the results of these graphs, non-dimensional pull-in and vdW parameters, which are defined in the text, vary linearly versus the other dimensionless parameters of the problem. Using this fact, some linear equations are presented to predict pull-in voltage, the maximum allowable length, the so-called detachment length, and the minimum allowable gap for a nano/micro-system. These linear equations are also reduced to a couple of universal pull-in formulas for systems with small initial gap. The accuracy of the universal pull-in formulas are also validated by comparing its results with available experimental and some previous geometric linear and closed-form findings published in the literature.

  13. On the 17-keV neutrino

    International Nuclear Information System (INIS)

    Hime, A.

    1993-04-01

    A brief review on the status of the 17-keV neutrino is presented. Several different experiments found spectral distortions which were consistently interpreted as evidence for a heavy neutrino admixture in β decay. Recent experiments, however, rule out the existence of a 17-keV neutrino as well as escaping criticisms of earlier null results. Moreover, the majority of positive results have been reinterpreted in terms of instrumental effects, despite the need for a different explanation in each case. Anomalies persist in the low energy region of the tritium spectrum which deserve further investigation

  14. Experimental cross sections for two-electron capture into nitrogen autoionising states in Nsup(q+) (q=6,7) on He and H/sub 2/ collisions at 10. 5q keV

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.; Dousson, S.; Hitz, D.

    1985-07-01

    Singly differential cross sections for two-electron capture into autoionising states (nl,n'l') with n=2,3,4 and n'>=n in Nsup(q+) (q=6,7) on He and H/sub 2/ collisions have been measured at 10,5q ke V collision energy and an observation angle thetasub(lab)=11.6/sup 0/. Total cross sections are estimated assuming isotropic angular distributions. (orig.).

  15. Experimental cross sections for two-electron capture into nitrogen autoionising states in Nsup(q+) (q=6,7) on He and H2 collisions at 10.5q keV

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.

    1985-01-01

    Singly differential cross sections for two-electron capture into autoionising states (nl,n'l') with n=2,3,4 and n'>=n in Nsup(q+) (q=6,7) on He and H 2 collisions have been measured at 10,5q ke V collision energy and an observation angle thetasub(lab)=11.6 0 . Total cross sections are estimated assuming isotropic angular distributions. (orig.)

  16. On the wide-energy-range tuning of x-ray photoemission electron microscope optics for the observation of the photoelectrons excited by several keV x-rays

    International Nuclear Information System (INIS)

    Yasufuku, H.; Yoshikawa, H.; Kimura, M.; Vlaicu, A.M.; Kato, M.; Kudo, M.; Fujikata, J.; Fukushima, S.

    2006-01-01

    We have newly developed an x-ray photoemission electron microscope (XPEEM) which uses both soft x-rays and hard x-rays at the undulator beam line BL15XU in the synchrotron radiation (SR) facility SPring-8 to observe various practical materials. In combination with an energy analyzer and high brilliant x-ray source, the detection of high kinetic energy inner-shell photoelectrons is essential for revealing the chemical properties of specimen subsurfaces or buried interfaces, owing to long inelastic mean free path of the high kinetic energy photoelectrons. The most significant result in our design is the new combined electric and magnetic field objective lens in which the magnetic field penetrates up to the sample surface. This allows the measurement with high spatial resolution of both low intensity images of inner-shell photoelectrons with high kinetic energy and high intensity images of secondary electrons. By using the sample bias scan method, we can easily change the focus condition of the objective lens in order to allow the energy filtered imaging with photoelectrons having the kinetic energy in a wide range (1-10 000 eV). By the combination of high brilliant SR x-rays, the new objective lens, and sample bias method, our XPEEM can successfully obtain the microarea x-ray photoelectron spectra and energy filtered XPEEM images of inner-shell photoelectrons, such as Si 1s, without any surface cleaning procedure. The energy filtered XPEEM image using photoelectrons from deep inner shells, Si 1s, was obtained for the first time

  17. Dynamic behaviour of a planar micro-beam loaded by a fluid-gap: Analytical and numerical approach in a high frequency range, benchmark solutions

    Science.gov (United States)

    Novak, A.; Honzik, P.; Bruneau, M.

    2017-08-01

    Miniaturized vibrating MEMS devices, active (receivers or emitters) or passive devices, and their use for either new applications (hearing, meta-materials, consumer devices,…) or metrological purposes under non-standard conditions, are involved today in several acoustic domains. More in-depth characterisation than the classical ones available until now are needed. In this context, the paper presents analytical and numerical approaches for describing the behaviour of three kinds of planar micro-beams of rectangular shape (suspended rigid or clamped elastic planar beam) loaded by a backing cavity or a fluid-gap, surrounded by very thin slits, and excited by an incident acoustic field. The analytical approach accounts for the coupling between the vibrating structure and the acoustic field in the backing cavity, the thermal and viscous diffusion processes in the boundary layers in the slits and the cavity, the modal behaviour for the vibrating structure, and the non-uniformity of the acoustic field in the backing cavity which is modelled in using an integral formulation with a suitable Green's function. Benchmark solutions are proposed in terms of beam motion (from which the sensitivity, input impedance, and pressure transfer function can be calculated). A numerical implementation (FEM) is handled against which the analytical results are tested.

  18. Autoionisation of N/sup 5 +/ (nln'l') with n = 2,3,4 and n' >= n measured by electron spectrometry in collisions of N/sup 7 +/ with He and H/sub 2/, at 4. 9 keV amu/sup -1/

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.; Dousson, S.; Hitz, D. (CEA Centre d' Etudes Nucleaires de Grenoble, 38 (France))

    1984-03-14

    a spectroscopic investigation of electrons coming from autoionising states N/sup 5 +/(nln'l'), with n=2,3,4 and n' >= n, of the fast ion has been made at 11.6/sup 0/ and 4.9 keV amu/sup -1/. Only exothermic reactions are observed. It is shown that the ionisation potential of the target has a strong influence on the more probable values of n and n'. In N/sup 7 +/-He collisions, the n=3, n'=3 configurations are the more excited. In N/sup 7 +/-H/sub 2/, the capture process is less selective since n=3, n' > 3 and also n=4, n' >= 4 configurations are strongly populated. In all these cases, the residual N/sup 6 +/ ion is left in an excited state (n=2 or 3). The n=2, n' > 2 excitation probability is found to be much smaller for the two collisional systems.

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

    International Nuclear Information System (INIS)

    Musgrove, A.R. de L.; Allen, B.J.; Macklin, R.L.

    1978-01-01

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

  20. 56Fe resonance parameters for neutron energies up to 850 keV

    International Nuclear Information System (INIS)

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

    1990-12-01

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

  1. 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.

  2. Effects of uranium bombardment by 20-40 KeV argon ions, Annex 2

    International Nuclear Information System (INIS)

    Nenadovic, T.; Jurela, Z.

    1966-01-01

    This paper shows the results of argon ions interaction with the polycrystal natural uranium. Thin foil of uranium about 200 μ was bombarded by 20-40 KeV argon ions. Coefficients of cathode scattering δ and secondary electrons emission γ were measured, during the process A + →U. The foil was then studied by transmission method and method of single step replica using an electron microscope [sr

  3. 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...

  4. Two-electron capture into autoionising configurations N/sup 4 +/(1snln'l') with n = 2,3,4 and n' >= n, observed by electron spectrometry in collisions of N/sup 6 +/(1s) with He and H/sub 2/, at 4. 2 keV amu/sup -1/

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Marrakchi, A.I.; Dousson, S.; Hitz, D.

    1984-04-14

    Double electron transfer into autoionising states N/sup 4 +/(1snln'l'), with n = 2,3,4 and n' >= n has been observed in a collision between a one-electron highly charged N/sup 6 +/(1s) ion and a two-electron target (He or H/sub 2/), by electron spectrometry. The same configurations are excited in the two collisional systems but with very different probabilities. Electron capture mainly occurs into 1s2ln'l' in He-systems whereas transfer into 1s3ln'l' is stronger in H/sub 2/ systems.

  5. Identification of an isomer in 110Ag at 1-keV excitation energy

    International Nuclear Information System (INIS)

    Clark, D.D.; Kostroun, V.O.; Siems, N.E.

    1975-01-01

    The existence of a new isomeric state in 110 Ag at approx. 1 keV excitation has been established in two experiments using a new instrument, the inner-shell-vacancy (ISV) detector. In the first experiment, a transition with a half-life of 660 plus-or-minus 40 ns was observed to follow the well-known 116-keV M4 transition that depopulates the 6 + 250-day isomeric level in 110 Ag; the energy of the new transition was deduced to be 109 Ag(n, γ) 110 Ag reaction to follow γ transitions previously assigned by others to populate a 1-keV excited state. The two results indicate the existence of a 2 - 660-ns isomer at 1.11 keV. Under the assumption that the newly observed transition is from a 2 - 1.11-keV state to the 1 + ground state, its hindrance factor with respect to the Moszkowski estimate is approx. 2.6 times 10 3 . Possible chemical-state perturbations of the measured half-life are estimated to be much smaller than the measurement error. In both experiments the approx. 1-keV transition was detected with the ISV detector, a new device based on the well-established atomic effect that within approx. 10 -14 s after the formation of an inner shell vacancy an atom will undergo a multiple loss of []lectrons ranging from several to 20 or more, the number being a function of Z and subshell. The emitted electrons, which are very soft, are collected with an accelerating and focusing electrostatic lens and detected with a plastic scintillator and a photomultiplier tube. Nuclear transitions that cause ISVs can thus be sensed. Experiments are described that show the detector is fast, sensitive, selective, and efficient in responding to ISVs.

  6. Experimental results on 2-30 keV bremsstrahlung from thick and thin targets

    Energy Technology Data Exchange (ETDEWEB)

    Shanker, R. [Atomic Physics Laboratory, Physics Department, Banaras Hindu University, Varanasi 221005 (India)]. E-mail: rshanker@bhu.ac.in

    2006-10-15

    The recent experimental investigations on electron bremsstrahlung produced from impact of 2-30 keV electrons with thick solid and thin gaseous targets are reviewed. The theoretical models describing the energy and angular distributions of bremsstrahlung photons are discussed with their brief outlines and formulations to explain the experimental data. The results on thick target bremsstrahlung (TTB) spectra produced by keV electrons have suggested that there is a need to develop a comprehensive theory for accounting the solid state effects. It is further noted that the prediction of the modified KKD formula gives a reasonable agreement with the TTB data, whereas a semi-empirical formula gives a better fit to the data for thick targets. The available experimental data for dependence of double differential cross-sections of emitted photons on impact energy and their emission angles for gaseous atoms and molecules exhibit a good agreement with the theoretical calculations of Kissel et al., [1983. Shape functions for atomic-field bremsstrahlung from electrons of kinetic energy 1-500 keV on selected neutral atoms 1

  7. Measurement X radiation > 30 KeV in the Brazilian magnetic anomaly with omnidirectional detectors

    International Nuclear Information System (INIS)

    Pinto Junior, O.; Gonzalez-Alarcon, W.D.; Gonzalez, A.L.C. de; Martin, I.M.; Dutra, S.L.G.; Pinto, I.R.C.A.; Pereira, A.E.C.; Senador, R.

    1982-07-01

    Atmospheric X-Rays measurements, with energies > 30 KeV, were performed at Sao Jose dos Campos-Brazil (23 0 S, 46 0 W Geographic) on April 14 and December 19, 1981, using omnidirectional NaI (Tl) scintillation counters on board stratospheric balloons. The main purpose of these measurements is to study the dynamics of precipitating electrons at the Brazilian Magnetic Anomaly. Studies on similar measurements during the previous decade seemed to show the existence of approximately 100 KeV precipitating electrons, possibly related to a coulomb scattering with the atmosophere. The studies on the recent measurements try not only to confirm such indications, but also to show further features of the dynamics of precipitating electrons, mainly during magnetically active time intervals. During such intervals, more energetic electrons (up to approximately 1000 KeV) also seem to precipitate, probably due to resonant wave-particle interactions at the low latitude inner magnetosphere. The collected data during the recent measurements seem to indicate the existence of such interactions. (Author) [pt

  8. One-electron capture into Li-like autoionising N4+ (1s2ln'l') configurations by metastable N5+ (1s2s3S) multicharged ions in collisions with He and H2, observed by electron spectrometry at 3.4 keV amu-1

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.

    1985-01-01

    One-electron capture into N 4+ (1s2ln'l') configurations, with n'=2 to 4, has been observed by electron spectrometry when a N 5+ (1s2s 3 S) multicharged ion beam encounters an He or H 2 target, at low collision velocity (upsilon=0.37 au) within single-collision conditions. Contributions of other 1s2l metastable states and of the 1s 2 ground state may be disregarded. A small indication of two-electron capture by 1s2s 3 S ions into (1s2s 3 S)3l3l' configurations is also seen. (author)

  9. Z/sub 1/ dependence of ion-induced electron emission from aluminum. [H/sup +/,H/sub 2//sup +/,D/sup +/,D/sub 2//sup +/,He/sup +/,B/sup +/,C/sup +/,N/sup +/,N/sub 2//sup +/,O/sup +/,O/sub 2//sup +/,F/sup +/,Ne/sup +/,S/sup +/,Cl/sup +/,Ar/sup +/,Kr/sup +/, and Xe/sup +/, 1. 2-50 keV

    Energy Technology Data Exchange (ETDEWEB)

    Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Jakas, M.M.; Oliva-Florio, A.

    1980-07-01

    We have measured the electron emission yields ..gamma.. of clean aluminum under bombardment with H/sup +/, H/sub 2/ /sup +/, D/sup +/, D/sub 2/ /sup +/, He/sup +/, B/sup +/, C/sup +/, N/sup +/, N/sub 2/ /sup +/, O/sup +/, O/sub 2/ /sup +/, F/sup +/, Ne/sup +/, S/sup +/, Cl/sup +/, Ar/sup +/, Kr/sup +/, and Xe/sup +/ in the energy range 1.2--50 keV. The clean surfaces were prepared by in situ evaporation of high-purity Al under ultra-high-vacuum conditions. It is found that kinetic electron emission yields ..gamma../sub k/, obtained after subtracting from the measured ..gamma.. a contribution due to potential emission, are roughly proportional to the electronic stopping powers, for projectiles lighter than Al. For heavier projectiles there is a sizable contribution to electron emission from collisions involving rapidly recoiling target atoms, which increases with the mass of the projectile, and which dominates the threshold and near-threshold behavior of kinetic emission. The results, together with recently reported data on Auger electron emission from ion-bombarded Al show that the mechanism proposed by Parilis and Kishinevskii of inner-shell excitation and subsequent Auger decay is negligible for light ions and probably small for heavy ions on Al and in our energy range. We thus conclude that kinetic electron emission under bombardment by low-energy ions results mainly from the escape of excited valence electrons.

  10. The accident of overexposure at the University hospital center of Toulouse. Expertise report n.1. Checking of experimental protocols of micro-beams calibration before and after dysfunction correction

    International Nuclear Information System (INIS)

    2007-01-01

    The regional center of stereotaxic radiosurgery of the University hospital center of Toulouse is equipped since april 2006 of a Novalis accelerator (Brainlab) devoted to the intra-skull stereotaxic radiosurgery. In april 2007, during an intercomparison of dosimetry computer files coming from different sites, the Brainlab society finds an anomaly in the files. The analysis made by the society concludes to to the use of an inappropriate detector for the measurement of a dosimetry parameter during the initial calibration of the accelerator. following this error, 145 patients (on the 172 treated by the service in question) suffer the consequences of an overdose whom importance is variable according the cases. The I.R.S.N. in charge of an expertise about the protocols of calibration of micro-beams before and after the correction of the dysfunction, took up with the search of the technical causes of the dysfunction. This report presents successively: the documents base on which is founded the expertise; the material of dosimetry and quality control necessary to the initial calibration of the device and to its follow-up; the formula made at the accelerator commissioning; the calibration of micro-beams in the two configurations that allows the device (micro-multi-knives and conic collimator) and the definition of parameters of the software of treatment planning; the maintenance and quality control implemented in the frame of its clinical use. (N.C.)

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

    Science.gov (United States)

    Böke, Aysun

    2014-09-01

    The linear attenuation coefficients and three interaction processes have been computed for liver, kidney, muscle, fat and for a range of x-ray energies from 1 keV to 150 keV. Molecular photoelectric absorption cross sections were calculated from atomic cross section data. Total coherent (Rayleigh) and incoherent (Compton) scattering cross sections were obtained by numerical integration over combinations of F2m(x) with the Thomson formula and Sm(x) with the Klein-Nishina formula, respectively. For the coherent (Rayleigh) scattering cross section calculations, molecular form factors were obtained from recent experimental data in the literature for values of xelements involved in tissue composition is 5 for liver, 47 for kidney, 44 for muscle and 3 for fat. The results are compared with previously published experimental and theoretical linear attenuation coefficients. In general, good agreement is obtained. The molecular form factors and scattering functions and cross sections are incorporated into a Monte Carlo program. The energy distributions of x-ray photons scattered from tissues have been simulated and the results are presented.

  12. One-electron capture into Li-like autoionising N/sup 4 +/ (1s2ln'l') configurations by metastable N/sup 5 +/ (1s2s/sup 3/S) multicharged ions in collisions with He and H/sub 2/, observed by electron spectrometry at 3. 4 keV amu/sup -1/

    Energy Technology Data Exchange (ETDEWEB)

    Bordenave-Montesquieu, A.; Benoit-Cattin, P.; Gleizes, A.; Dousson, S.; Hitz, D.

    1985-04-14

    One-electron capture into N/sup 4 +/ (1s2ln'l') configurations, with n'=2 to 4, has been observed by electron spectrometry when a N/sup 5 +/ (1s2s /sup 3/S) multicharged ion beam encounters an He or H/sub 2/ target, at low collision velocity (upsilon=0.37 au) within single-collision conditions. Contributions of other 1s2l metastable states and of the 1s/sup 2/ ground state may be disregarded. A small indication of two-electron capture by 1s2s /sup 3/S ions into (1s2s /sup 3/S)3l3l' configurations is also seen.

  13. Test of a compact 750 keV H- preinjector

    International Nuclear Information System (INIS)

    Meitzler, C.R.; Datte, P.; Huson, F.R.; Kazimi, R.; Kronke, C.; Machida, S.; MacKay, W.; Ohnuma, S.; Raparia, D.; Sun, D.; Tompkins, P.; Ziegler, J.

    1989-01-01

    A 750 keV RFQ based accelerator is being developed at the Texas Accelerator Center. A modified magnetron ion source will produce 10--100 mA of 30 keV H - beam. A 35 keV transport line that transports the beam from the ion source to the entrance of the RFQ without becoming neutralized has been designed and is under construction. The RFQ is a 86 cm long, four rod structure that operates at 470 MHz. Results of tests on the cold model are reported. 5 refs

  14. Consequences of a 17-keV neutrino

    International Nuclear Information System (INIS)

    Caldwell, D.O.; Langacker, P.

    1991-01-01

    If the controversial 17-keV neutrino exists, laboratory, astrophysical and cosmological bounds, unless significantly weakened, require that (1) it be a Majorana neutrino and mainly ν τ ; (2) it not be the dark matter of the universe, although its existence would rule out dominant hot dark matter; (3) the ν μ be a heavy Majorana neutrino of mass 17 keV or in the range 170--270 keV; and (4) the Mikheyev-Smirnov-Wolfenstein solution to the solar-neutrino problem involve ν e conversion to a light sterile [SU(2)-singlet] neutrino

  15. Influence of ∼7 keV sterile neutrino dark matter on the process of reionization

    International Nuclear Information System (INIS)

    Rudakovskyi, Anton; Iakubovskyi, Dmytro

    2016-01-01

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

  16. 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}

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

    International Nuclear Information System (INIS)

    Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A.; Godunov, A.L.; Schipakov, V.A.

    1997-01-01

    Excitation cross sections of the (2s 2 ) 1 S, (2p 2 ) 1 D , and (2s2p) 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 total cross sections as well as magnetic sublevel populations. These new experimental data are briefly compared with out theoretical calculations. copyright 1997 The American Physical Society

  18. Some early results of the keV plasma experiment on GEOS-1

    International Nuclear Information System (INIS)

    Borg, H.; Holmgren, L.-A.; Hultqvist, B.; Cambou, F.; Reme, H.

    1978-01-01

    Some preliminary new results are presented of the keV plasma experiment on GEOS-1. Electrons and ions have been observed to stream along the magnetic field lines in the dayside magnetosphere from the ionospheric side of the satellite towards the equatorial plane during magnetic storms, with streaming velocities corresponding to a kinetic energy of the order of a keV. The opposite streaming velocity has also been seen, but primarily in the ions only and with a smaller flux ratio for the two opposite directions along the field lines. The transition between the two opposite streaming directions, as seen by the satellite, has been found to occur even in a fraction of a second. In magnetic storm conditions azimuthal asymmetries in ion fluxes corresponding to electric field intensities of several tens of millivolts per meter have been observed. (Auth.)

  19. Sputtering of solid nitrogen and oxygen by keV hydrogen ions

    DEFF Research Database (Denmark)

    Ellegaard, O.; Schou, Jørgen; Stenum, B.

    1994-01-01

    Electronic sputtering of solid nitrogen and oxygen by keV hydrogen ions has been studied at two low-temperature setups. The yield of the sputtered particles has been determined in the energy regime 4-10 keV for H+, H-2+ and H-3+ ions. The yield for oxygen is more than a factor of two larger than...... that for nitrogen. The energy distributions of the sputtered N2 and O2 molecules were measured for hydrogen ions in this energy regime as well. The yields from both solids turn out to depend on the sum of the stopping power of all atoms in the ion. The yield increases as a quadratic function of the stopping power...

  20. Intensity and anisotropy variations of precipitating particle fluxes with the energy above 30 keV

    International Nuclear Information System (INIS)

    Altyntseva, V.I.; Dronov, A.V.; Kovtyukh, A.S.; Panasyuk, M.I.; Polekh, N.M.; Rejzman, S.Ya.; Sosnovets, Eh.N.

    1982-01-01

    Space-time variations of 50-80 keV electron and 210-320 keV proton precipitations during magnetic storm on 29. 07. 77 and magnetic perturbed period (Ksub(p) >= 4) on 8. 04. 77 are compared using the Kosmos 900 satellite data. The structure of electron and proton isotropization regions is significantly different: for electrons isotropic flows are localized in narrow zones inside the precipitation area and for protons they occupy practically the whole precipitation region. The relative position of plasma pause and the proton precipitation region testify also to the effect of magnetosphere convection on the space-time variations of the proton participation. The highest proton precipitation was observed in the evening-night sector and electrons - in the morning-day sector. The proton precipitation region consists of a narrow low-latitudinal zone with the anisotropic pitch-angular distribution and of an extended zone of isotropic flows. The cigar-shaped pitch-angular electron distribution was observed in the auroral area

  1. Development of micro-beam NRA for 3D-mapping of hydrogen distribution in solids: Application of tapered glass capillary to 6 MeV 15N ion

    International Nuclear Information System (INIS)

    Sekiba, D.; Yonemura, H.; Nebiki, T.; Wilde, M.; Ogura, S.; Yamashita, H.; Matsumoto, M.; Kasagi, J.; Iwamura, Y.; Itoh, T.; Matsuzaki, H.; Narusawa, T.; Fukutani, K.

    2008-01-01

    A micro-beam NRA system, by means of a resonant nuclear reaction 1 H( 15 N, αγ) 12 C, has been developed for the purpose of the 3D mapping of the hydrogen distribution in solids. To obtain the tens μm size of the beam spot, the combination of the newly proposed tapered glass capillary and a conventional quadrupole magnetic lens is employed. An Y patterned film on a substrate is prepared as an application of the developed system. The 6 MeV 15 N beam focused by glass capillaries down to 50 μm successfully shows the hydrogen distribution. The in-plane NRA profile implies that the beam emitted from the glass capillary outlet is parallel, although the original beam has a considerable divergence. The NRA measurements in the 10 3 Pa N 2 atmosphere due to the low gas conductance of the glass capillary is also demonstrated

  2. On generation of high power x-rays in the range 7-20 keV

    International Nuclear Information System (INIS)

    Ratakhin, N.A.

    1997-01-01

    An attempt is made on the base of general relations to evaluate possibility of two approaches to the problem of receiving powerful x-radiation id spectral range of (7-20) keV. Extremely cut possibilities of electron beams of vacuum diodes and Z-pinch plasma thermal radiation are shown. Some perspectives of increasing such radiation power in connection with possibility of generation of high-energy electrons in Z-pinch plasma are noted

  3. 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...

  4. Inelastic scattering of 275 keV neutrons by silver

    International Nuclear Information System (INIS)

    Litvinsky, L.L.; Zhigalov, Ya.A.; Krivenko, V.G.; Purtov, O.A.; Sabbagh, S.

    1997-01-01

    Neutron total, elastic and inelastic scattering cross-scattering of Ag at the E n = 275 KeV neutron energy were measured by using the filtered neutron beam of the WWR-M reactor in Kiev. The d-neutron strength function S n2 of Ag was determined from the analysis of all available data in the E n ≤ keV energy region on neutron inelastic scattering cross-sections with excitation of the first isomeric levels I π m = 7/2 + , E m ∼ 90 keV of 107,109 Ag: S n2 = (1.03 ± 0.19) · 10 -4 . (author). 10 refs, 3 figs

  5. Design study of 500 keV H- accelerator for ITER NB system

    International Nuclear Information System (INIS)

    Kashiwagi, Mieko; Inoue, Takashi

    2009-02-01

    In the neutral beam (NB) system for heating and current drive of ITER, detailed designs of a five stage Multi Aperture and Multi Grid (MAMuG) accelerator to produce 1 MeV 40 A D- and 870 keV 46 A H - ion beams are ongoing. However, it was expected that shinethrough power from the 870 keV H 0 beam was above tolerable level for the maximum plasma density prior to any H mode. Therefore, it was required to reduce the beam energy to 500 keV with maintaining high beam current. The objective of this study is to identify necessary modifications from the original five stage accelerator to a three stage accelerator to produce 500 keV H - ion beam through the physics design based on a beam optics, a beamlet steering and a stripping loss of negative ions. In the beam optics study utilizing a 2D beam analysis code, necessary modifications in aperture diameter, grid thickness and grid spacing were proposed. In a 3D multi beamlets analysis, aperture offsets in the ESG (Electron Suppression Grid) to compensate beamlet deflections and another aperture offset in the GRG (GRounded Grid) to steer the beamlets to a focal point were designed. In a 3D gas flow analysis, it was confirmed that stripping loss of negative ions was not changed and gas density around the beam source satisfied a design requirement for high voltage holding in a modified accelerator configuration proposed in the beam optics study. Finally, the items for modification were summarized. (author)

  6. Pu241 cross-sections below 1 keV

    International Nuclear Information System (INIS)

    Doherty, G.

    1966-12-01

    Early in 1965 a new data file (DFN 40) for Pu241 covering the energy range 10 - 4 eV to 15 MeV was prepared for the UKAEA Nuclear Data Library. The data above 1 keV are described by Douglas (AWRE 0-101/64) and the data below 1 keV are set out in this report. During the past year a number of additional measurements have been reported for Pu241 and a brief summary of these measurements and their implications for the data on the file are given. (author)

  7. Absolute cross sections for the multielectron processes in 15 keV I10++rare gas collisions

    International Nuclear Information System (INIS)

    Nakamura, N.; Currell, F.J.; Danjo, A.; Kimura, M.; Matsumoto, A.; Ohtani, S.; Sakaue, H.A.; Sakurai, M.; Tawara, H.; Watanabe, H.; Yamada, I.; Yoshino, M.

    1995-01-01

    We have experimentally determined the absolute cross sections for total charge transfer (σ q ), j electron transfer (σ j q ), i electron capture (σ q,q-i ) and each reaction process (σ j q,q-i ) in 15 keV I 10+ -Ne, Ar, Kr and Xe collisions. The branching ratios were determined by the coincidence measurements between charge changing projectile and recoil ions. The electron capture cross sections were measured by the initial growth rate method. The experimental results for total and j electron transfer cross sections were compared with the predictions of the extended classical over-barrier model (ECBM). (orig.)

  8. Differential cross sections for single ionization of H2 by 75keV proton impact

    International Nuclear Information System (INIS)

    Chowdhury, U; Schulz, M; Madison, D H

    2012-01-01

    We have calculated Triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H 2 by 75 keV proton impact using the molecular 3 body distorted wave Eikonal initial state (M3DW-EIS) approach. Previously published measured DDCS-P (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles which were interpreted as an interference resulting from the two-centered potential of the molecule.

  9. 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…

  10. 750 keV beam line construction at the KEK

    International Nuclear Information System (INIS)

    Ishimaru, H.; Anami, S.; Inagaki, T.; Sakaue, T.; Itoh, K.; Fukumoto, S.

    1976-01-01

    The construction of 750 keV beam line of the KEK injector of the 12 GeV proton synchrotron was described. The beam line consists of the beam focusing quadrupoles, vacuum system, the electrostatic chopper and the various beam monitors. (author)

  11. Determination of integral K-shell Compton scattering cross-sections in elements 41>=Z>=51 for 1250 keV photons

    Energy Technology Data Exchange (ETDEWEB)

    Verma, S L; Allawadhi, K L; Sood, B S [Punjabi Univ., Patiala (India). Dept. of Physics

    1978-04-01

    Integral K-shell Compton scattering cross-sections in elements Nb, Mo, Ag, Cd, In, Sn and Sb have been determined for 1250 keV photons. The results when compared with theory suggest that K-shell electrons in the elements under investigation behave as free electrons.

  12. Excitation of the helium autoionizing states in He++He collisions, between 3 and 140 keV

    International Nuclear Information System (INIS)

    Bordenave-Montesquieu, A.; Gleizes, A.; Benoit-Cattin, P.

    1982-01-01

    The autoionization of the helium atom has been experimentally studied in He + +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 2 1 S, 2s2p 3 P, 2p 2 1 D, and 2s2p 1 P are determined by a numerical fitting procedure which is reported in detail; below 10 keV the ( 1 D+ 1 P), and 2p 2 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 2 1 D and 2s2p 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 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 3 P cross section strengthens this interpretation. These total cross sections are compared with those estimated from earlier H + +He data published by us; similar autoionization cross-section values are expected for the two systems at high collision velocity

  13. Calibration of hard x-ray (15 - 50 keV) optics at the MPE test facility PANTER

    Science.gov (United States)

    Bräuninger, Heinrich; Burkert, Wolfgang; Hartner, Gisela D.; Citterio, Oberto; Ghigo, Mauro; Mazzoleni, Francesco; Pareschi, Giovanni; Spiga, Daniele

    2004-02-01

    The Max-Planck-Institut für extraterrestrische Physik (MPE) in Garching, Germany, operates the large X-ray beam line facility PANTER for testing astronomical systems. At PANTER a number of telescopes like EXOSAT, ROSAT, SAX, JET-X, ABRIXAS, XMM and SWIFT operating in the soft energy range (0.02 - 15 keV) have been successfully calibrated. In the present paper we report on an important upgrade recently implemented that enables the calibration of hard X-ray optics (from 15 up to 50 keV). Currently hard X-ray optics based on single and multilayer coating are being developed for several future X-ray missions. The hard X-ray calibrations at PANTER are carried out by a high energy source based on an electron gun and several anodes, able to cover the energy range from 4.5 up to 50 keV. It provides fluxes up to 104 counts/sec/cm2 at the instrument chamber with a stability better than 1%. As detector a pn-CCD camera operating between 0.2 and 50 keV and a collecting area of 36 cm2 is used. Taking into account the high energy resolution of the CCD (145 eV at 6 keV), a very easy way to operate the facility in hard X-ray is in energy-dispersive mode (i.e. with a broad-band beam). A double crystal monochromator is also available providing energies up to 20 keV. In this paper we present the first results obtained by using PANTER for hard X-ray characterizations, performed on prototype multilayer optics developed by the Osservatorio Astronomico di Brera (OAB), Milano, Italy, and the Harvard-Smithsonian Center for Astrophysics (CfA), Cambridge, MA, USA.

  14. Modified Sternglass theory for the emission of secondary electrons by fast-electron impact

    International Nuclear Information System (INIS)

    Suszcynsky, D.M.; Borovsky, J.E.

    1992-01-01

    The Sternglass theory [Sternglass, Phys. Rev. 108, 1 (1957)] for fast-ion-induced secondary-electron emission from metals has been modified to predict the secondary-electron yield from metals impacted by energetic (several keV to about 200 keV) electrons. The primary modification of the theory accounts for the contribution of the backscattered electrons to the production of secondary electrons based on a knowledge of the backscattered-electron energy distribution. The modified theory is in reasonable agreement with recent experimental data from gold targets in the 6--30-keV electron energy range

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

    International Nuclear Information System (INIS)

    Lobo, Georges; Corvi, Franco; Schillebeeckx, Peter; Brusegan, Antonio; Mutti, Paolo; Janeva, Natalia

    2002-01-01

    The average capture cross-section of 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 6 D 6 liquid scintillators and the neutron flux was measured with a 10 B-loaded ionisation chamber. The data, corrected with the pulse-height weighting technique, have been normalised to the well-isolated and nearly saturated 232 Th (n, γ) 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)

  16. Calculated and measured W values in N2, Ar, CH4 and CO2 gases for ions H+, He+, C+, N+, O+ and Ar+ in the energy range 25 KeV to 375 KeV

    International Nuclear Information System (INIS)

    Nguyen Van Dat; Chemtob, Maurice.

    1979-01-01

    The present paper describes the experimental method used for measurement of W values in argon gas and in the three components of T.E. gas: nitrogen, methane and carbon dioxide, for ions with masses in the range 1 to 40 a.m.u. and with energies in the range 25 KeV to 375 KeV. For these ions, the incident velocities are comparable to the electron orbital velocities. At these velocities energy losses due to elastic scattering and electron capture processes are expected to become significant as compared to ionization and excitation which predominate at higher velocities. These measured W values are then compared to calculated values. These calculations are obtained by introducing the inelastic and elastic stopping power cross sections in a transport equation, the resolution of which gives ionization range and the amount of energy released to produce ionization

  17. On the Spectral Hardening at gsim300 keV in Solar Flares

    Science.gov (United States)

    Li, G.; Kong, X.; Zank, G.; Chen, Y.

    2013-05-01

    It has long been noted that the spectra of observed continuum emissions in many solar flares are consistent with double power laws with a hardening at energies gsim300 keV. It is now widely believed that at least in electron-dominated events, the hardening in the photon spectrum reflects an intrinsic hardening in the source electron spectrum. In this paper, we point out that a power-law spectrum of electrons with a hardening at high energies can be explained by the diffusive shock acceleration of electrons at a termination shock with a finite width. Our suggestion is based on an early analytical work by Drury et al., where the steady-state transport equation at a shock with a tanh profile was solved for a p-independent diffusion coefficient. Numerical simulations with a p-dependent diffusion coefficient show hardenings in the accelerated electron spectrum that are comparable with observations. One necessary condition for our proposed scenario to work is that high-energy electrons resonate with the inertial range of the MHD turbulence and low-energy electrons resonate with the dissipation range of the MHD turbulence at the acceleration site, and the spectrum of the dissipation range ~k -2.7. A ~k -2.7 dissipation range spectrum is consistent with recent solar wind observations.

  18. ON THE SPECTRAL HARDENING AT ∼>300 keV IN SOLAR FLARES

    International Nuclear Information System (INIS)

    Li, G.; Kong, X.; Zank, G.; Chen, Y.

    2013-01-01

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

  19. 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

  20. Solar neutrino flux at keV energies

    Science.gov (United States)

    Vitagliano, Edoardo; Redondo, Javier; Raffelt, Georg

    2017-12-01

    We calculate the solar neutrino and antineutrino flux in the keV energy range. The dominant thermal source processes are photo production (γ e→ e νbar nu), bremsstrahlung (e+Ze→ Ze+e+νbar nu), plasmon decay (γ→νbar nu), and νbar nu emission in free-bound and bound-bound transitions of partially ionized elements heavier than hydrogen and helium. These latter processes dominate in the energy range of a few keV and thus carry information about the solar metallicity. To calculate their rate we use libraries of monochromatic photon radiative opacities in analogy to a previous calculation of solar axion emission. Our overall flux spectrum and many details differ significantly from previous works. While this low-energy flux is not measurable with present-day technology, it could become a significant background for future direct searches for keV-mass sterile neutrino dark matter.

  1. Electronics

    Science.gov (United States)

    2001-01-01

    International Acer Incorporated, Hsin Chu, Taiwan Aerospace Industrial Development Corporation, Taichung, Taiwan American Institute of Taiwan, Taipei, Taiwan...Singapore and Malaysia .5 - 4 - The largest market for semiconductor products is the high technology consumer electronics industry that consumes up...Singapore, and Malaysia . A new semiconductor facility costs around $3 billion to build and takes about two years to become operational

  2. Auroral electron energies

    International Nuclear Information System (INIS)

    McEwan, D.J.; Duncan, C.N.; Montalbetti, R.

    1981-01-01

    Auroral electron characteristic energies determined from ground-based photometer measurements of the ratio of 5577 A OI and 4278 A N 2 + emissions are compared with electron energies measured during two rocket flights into pulsating aurora. Electron spectra with Maxwellian energy distributions were observed in both flights with an increase in characteristic energy during each pulsation. During the first flight on February 15, 1980 values of E 0 ranging from 1.4 keV at pulsation minima to 1.8 keV at pulsation maxima were inferred from the 5577/4278 ratios, in good agreement with rocket measurements. During the second flight on February 23, direct electron energy measurements yielded E 0 values of 1.8 keV rising to 2.1 keV at pulsation maxima. The photometric ratio measurements in this case gave inferred E 0 values about 0.5 keV lower. This apparent discrepancy is considered due to cloud cover which impaired the absolute emission intensity measurements. It is concluded that the 5577/4278 ratio does yield a meaningful measure of the characteristic energy of incoming electrons. This ratio technique, when added to the more sensitive 6300/4278 ratio technique usable in stable auroras can now provide more complete monitoring of electron influx characteristics. (auth)

  3. Dipole stabilizer rods for 400 keV deuteron RFQ

    International Nuclear Information System (INIS)

    Sista, V.L.S. Rao; Srivastava, S.C.L.; Pande, Rajni; Roy, Shweta; Singh, P.

    2009-01-01

    In our 400 keV deuteron RFQ for neutron production, the destructive dipolar modes are very close to the required quadrupolar mode. In order to increase the spacing between the quadrupole and dipole modes the dipolar stabilizer rods (DSR's) are used. The design of the DSR's is done using the computer code CST Microwave studio. The variation of the quadrupole and dipolar mode frequencies with the radius and length of the DSR's are studied. (author)

  4. ORNL 150 keV neutral beam test facility

    International Nuclear Information System (INIS)

    Gardner, W.L.; Kim, J.; Menon, M.M.; Schilling, G.

    1977-01-01

    The 150 keV neutral beam test facility provides for the testing and development of neutral beam injectors and beam systems of the class that will be needed for the Tokamak Fusion Test Reactor (TFTR) and The Next Step (TNS). The test facility can simulate a complete beam line injection system and can provide a wide range of experimental operating conditions. Herein is offered a general description of the facility's capabilities and a discussion of present system performance

  5. Direct observation of indium compositional fluctuation in GaInN/GaN multi-quantum wells using an X-ray micro-beam from the 8-GeV storage ring

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Takao; Uemura, Shigeaki; Kudo, Yoshihiro; Fuutagawa, Noriyuki [Materials Laboratories, Sony Corporation, 4-14-1 Asahi-cho, Atsugi, Kanagawa 243-0014 (Japan); Terada, Yasuko [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

    2008-07-01

    We measured the micrometer-scale fluctuation of the indium contents in a 50 {mu}m x 30 {mu}m region of annealed Ga{sub 0.8}In{sub 0.2}N/GaN multi quantum wells by mapping the counts of indium fluorescent X-rays excited by a 1.3 {mu}m x 3.8 {mu}m X-ray micro-beam. The mapping indicates that two distinct regions - indium-rich and indium-poor regions - are formed by the annealing. The indium contents in the island-shaped low-indium regions are 20% less than in the surrounding high-indium region. As the island-shaped low-indium regions clearly coincide with the low-radiative regions as observed by Hg-lamp-excited fluorescent microscopy, we believe that the low-radiative regions are a result not of indium segregation but of the generation of defects such as plane defects. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  6. Energy absorption coefficients for 662 keV gamma ray in some fatty acids

    International Nuclear Information System (INIS)

    Bhandal, G.S.; Singh, K.; Rama Rani; Vijay Kumar

    1993-01-01

    The mass energy absorption coefficient refers to the amount of energy dissipation by the secondary electron set in motion as a result of interactions between incident photons and matter. Under certain conditions, the energy dissipated by electrons in a given volume can be equated to the energy absorbed in that volume. The absorbed energy is of basic interest in radiation dosimetry because it represents the amount of energy made available for the production of chemical or biological effects. Sphere transmission is employed for the direct measurement of mass energy absorption coefficients at 662 keV in some fatty acids. Excellent agreement is obtained between the measured and theoretical values. (author). 6 refs., 1 fig., 1 tab

  7. 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.

  8. X-ray fluorescence in Member States (India): Micro-beam X-ray fluorescence spectroscopy using Indus-2 synchrotron radiation facility: beamline BL-16

    Energy Technology Data Exchange (ETDEWEB)

    Tiwari, M. K.; Lodha, G. S.; Deb, S.K., E-mail: mktiwari@rrcat.gov.in [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (MP) (India)

    2014-02-15

    Indus-1 and Indus-2, are India’s national synchrotron radiation facilities located at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore. Indus-1 is a 450 MeV electron storage ring which provides synchrotron radiation in the VUV soft x-ray range with a critical wavelength of 61 Å whereas Indus-2 is a 2.5 GeV, 300 mA synchrotron radiation machine with a critical wavelength of 2 Å for its bending magnet source. The Indus-2 is at present operating at 2.5 GeV, 100 mA in round-theclock operation mode. Both synchrotron sources exist in the same premises of RRCAT, Indore and have very good air/rail connectivities with major cities of India. The RRCAT centre also fosters research and development activities in the fields of particle accelerators, Lasers and related advanced technologies like cryogenics, ultra high vacuum, superconducting cavities, RF power, magnet and their application in different fields of science, thus the centre provides a unique platform covering a wide range of experiments for the synchrotron users in the Indian subcontinent.

  9. The repetitive flaking of Inconel 625 by 100 keV helium bombardment

    International Nuclear Information System (INIS)

    Whitton, J.L.; Chen, H.M.; Littmark, U.

    1981-01-01

    Repetitive flaking of Inconel 625 occurs with ion bombardment doses of > than 10 18 100 keV helium ions cm -2 , with up to 39 exfoliations being observed after bombardment with 3 x 10 19 ions cm -2 . The thickness of the flakes, measured by scanning electron microscopy, is some 30% greater than when measured by Rutherford backscattering (RBS) of 1.8 MeV helium ions. These RBS measurements compare well with the thickness of the remaining layers in the resultant craters and to the most probable range of the 100 keV helium. The area of the flakes is dictated by the grain boundaries, and when one flake is ejected, the adjacent grains are prevented from doing so since there now exists an escape route for the injected helium. A strong dose rate dependence is observed; decreasing the beam current from 640 μA cm -2 to 64 μA cm -2 results in a factor 20 fewer flakes being exfoliated (for the same total dose of 3 x 10 19 ions cm -2 ). Successive flakes decrease in area, suggesting that eventually a cratered, but stable, surface will result with the only erosion being by the much less effective mechanism of sputtering. (orig.)

  10. Commissioning experiences on high voltage generator of 750 KeV DC accelerator at RRCAT, Indore

    International Nuclear Information System (INIS)

    Banwari, R.; Kasliwal, A.; Pandit, T.G.

    2009-01-01

    Design approach of high voltage generator for 750 keV DC accelerator, developed at RRCAT Indore, inculcates a unique feature of high frequency operation of symmetrical Cockcroft-Walton voltage generator. Apart from design simplicity and feasibility of modular construction, the high frequency use of symmetrical Cockcroft-Walton circuit gives added advantages of less ripple, better regulation, faster response and low stored energy in the system. Additionally the scheme allows us the use of low voltage, light weight components thus improving the overall economy of the system. The accelerator has been commissioned and made operational at its rated energy of 750 keV in the recent past. With brief introduction on design aspects of high voltage generator and filament power supply of this accelerator, the paper presented here describes the developmental steps of various components with focus on challenges encountered and solutions implemented. Development of high frequency inverter, high voltage ferrite core transformer, compensating inductors, interface bushings, voltage multiplier stack, and filament transformer along with floating power supply for electron emitter of the accelerator has been dealt in detail. The failures encountered during commissioning stages of the accelerator have been reported with measures taken for improvement of the specific components. Intricacies of the reflected capacitance of the multiplier stack and arc-current ground return are also described with their effects on system operation and reliability. (author)

  11. 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...

  12. Neutron transmission and capture measurements and analysis of 60Ni from 1 to 450 keV

    International Nuclear Information System (INIS)

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

    1982-11-01

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

  13. Experimental Set-up for Irradiation of Solid H2 and D2 with Charged Particles of keV Energies

    DEFF Research Database (Denmark)

    Sørensen, H.

    1976-01-01

    crystal film thickness monitor. The target plate, which can be heated so that films are removable by evaporation, may be used both as a calorimeter and as a beam current collector. Methods for measurement of secondary electron emission coefficients were developed, and preliminary measurements were made...... with electrons and hydrogen ions. For electron bombardment, the secondary electron emission coefficient of solid deuterium was much smaller than one. It was shown possible to use the set-up to study beam desorption of very thin films. Furthermore the set-up could be used for measuring the energy......An experimental facility was built where films of solid deuterium (and hydrogen) may be made with known thickness and irradiated with pulsed beams of electrons (up to 3 keV) and light ions (up to 10 keV). Films are made on a target plate held at 2.5–3 K. Film growth rate is calibrated with a quartz...

  14. Nature of the 153 and 270 keV transitions in /sup 119/Sb from sup(119m)Te

    Energy Technology Data Exchange (ETDEWEB)

    Sahota, H S [Punjabi Univ., Patiala (India). Dept. of Physics

    1982-08-01

    The 153 and 270 keV transitions in /sup 119/Sb have been investigated for the presence of any anomalous conversion through conversion electron intensity and conversion-electron gamma and gamma-gamma directional correlation measurements. The resulting subshell ratios and particle rarameters have been analysed for the accurate determination of mixing ratios for the transitions. The results are delta/sub 153/ = +-0.0025 and delta/sub 270/ = 0.10 sub(-0.20)sup(+0.03). The conversion process has been found to be normal in both cases.

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

    International Nuclear Information System (INIS)

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

    1982-01-01

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

  16. Substorm morphology of >100 keV protons

    International Nuclear Information System (INIS)

    Lundblad, J.Aa.; Soeraas, F.; Aarsnes, K.

    1978-06-01

    The latitudinal morphology of >100 keV protons at different local times has been studied as a function of substorm activity Acharacteristic pattern has been found: During quiet times there is an isotropic zone centered around 67 0 near midnight, but located on higher latitudes towards dusk and dawn. This zone moves slightly equatorward during the substorm growth phase. During the expansive phase the precipitation spreads poleward apparently to approximately 71 0 near midnight. The protons are precipitated over a large local time interval on the night side, but the most intense fluxes are found in the pre-midnight sector. A further poleward expansion, to more than 75 0 near midnight, seems to take place late in the substorm. Away from midnight the expansion reaches even higher latitudes. During the recovery phase the intensity of the expanded region decreases gradually; the poleward boundary is almost stationary if the interplanetary magnetic field has a northward component and no further substorm activity takes place. Mainly protons with energy below approximately 500 keV are precipitated in the expanded region. On the dayside no increase in the precipitation rates is found during substorm expansion, but late in the substorm an enhanced precipitation is found, covering several degrees of latitude. The low-latitude anisotropic precipitation zone is remarkably stable during substorms. A schematic model is presented and discussed in relation to earlier results. (Auth.)

  17. Linac4 45 keV Proton Beam Measurements

    CERN Document Server

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

    2013-01-01

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

  18. Compact 80-keV neutral-beam module

    International Nuclear Information System (INIS)

    Molvik, A.W.; Baird, E.D.; Berkner, K.H.; Cooper, W.S.; Duffy, T.J.; Ehlers, K.W.; Fink, J.; Garner, D.; Wilder, C.

    1977-01-01

    A compact and maintainable source of 80-keV neutral beams that focus to a high power density is required for the Mirror Fusion Test Facility (MFTF). In the new source being designed and built to meet these requirements, the cross-sectional area is reduced in two ways: by immersing the source in a vacuum where high voltage can be held over smaller distances and by redesigning grid supporting structures. Reliability is increased by reducing the electric fields everywhere else below those present between grids and by design innovations. The latter include techniques to reduce stray magnetic field and disperse gas uniformly, all metal-ceramic construction, and a 60-kV shield enclosing all 80-kV electrodes. Wherever possible, we have attempted to simplify the construction. We expect to solve problems that arise during testing either with add-on fixes or with the techniques already tested successfully on the Lawrence Berkeley Laboratory (LBL) 120-keV source. Easy maintenance is obtained by a compact isolation valve and by modular construction. Curving both the grid wires and their holders provides focusing in two planes

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

    International Nuclear Information System (INIS)

    Godunov, A.L.; Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Benhenni, M.; Bordenave-Montesquieu, A.

    1997-01-01

    A joint theoretical and experimental study of the excitation of the autoionizing (2s 2 ) 1 S, (2p 2 ) 1 D and (2s2p) 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 2 ) 1 D and (2s2p) 1 P resonances and reveal an evident distortion of the resonance profiles by CIFS for forward electron ejection angles below 40 o . (author)

  20. 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).

  1. Protection and measurement systems for 500 keV DC industrial accelerator

    International Nuclear Information System (INIS)

    Rajan, R.N.; Saroj, P.C.; Nanu, K.; Sharma, D.K.; Bakhtsingh, R.I.; Pandey, M.K.; Aggarwal, Ritu; Nagesh, K.V.; Sethi, R.C.

    2003-01-01

    A 500 keV, 20 ma electron beam accelerator has been developed and commissioned for industrial processing application at BRIT, Vashi. The 500 kV supply system consists of a 10 kV/2a DC power supply, 15 kW/10 kHz oscillator, 60 kV/10 kHz step-up transformer, and a 10 stage balanced Cockcroft-Walton multiplier. Since this is a high voltage system, and is prone to generate high electrical surges in the event of fault, adequate protection measures have to be incorporated to prevent catastrophic failure to the components of the supply system and also for measurement and control devices. Two level safety protection schemes have been incorporated in this system. This paper describes about various safety measures incorporated in the system and a few system specific measurement schemes

  2. Scattering of light keV ions from amorphous and crystalline solid surfaces

    International Nuclear Information System (INIS)

    Robinson, J.E.; Kwok, K.K.; Thompson, D.A.

    1976-01-01

    Total reflection coefficients (R), backscattered energy fractions (γ), and backscattered energy spectra are evaluated using a binary collision Monte Carlo technique for a variety of light ions (H, D, T, He) in the energy range 0.25-8 keV, incident on amorphous targets (C, Fe, Nb). The scattering is also evaluated for H on Nb for a range of incident angles and two electronic stopping values. The average scattered energy per reflected particle and the backscattered energy spectra are found to vary in a universal manner as a function of the reflection coefficient between the Rutherford high energy limit and a low energy multiple collision limit. Single crystal effects are also briefly discussed using a diffusional dechanneling model. (Auth.)

  3. (5/2-→5/2+) 803 keV beta transition in 147Nd

    International Nuclear Information System (INIS)

    Lakshminarayana, S.; Srinivasa Rao, M.; Seshagiri Rao, V.; Sastry, D.L.

    1978-01-01

    The existing experimental results on the 5/2 - →5/2 + 803 keV beta transition in 147 Nd are mutually contradictory to classify it under xi-approximation. To resolve this contradiction, the β-γ directional correlations are performed carefully as a function of energy using a conventional fast-slow coincidence scintillation system. The attenuation factor G 2 in this case turns out to be 0.64 +- 0.05. The results on the longitudinal electron polarization and the shape measurements are combined with the present results and an attempt is made to extract the nuclear matrix elements governing this first forbidden non-unique beta transition following Simm's formalism. Results are discussed based on the final sets of matrix elements. (auth.)

  4. 380 keV proton irradiation effects on photoluminescence of Eu-doped GaN

    International Nuclear Information System (INIS)

    Okada, Hiroshi; Nakanishi, Yasuo; Wakahara, Akihiro; Yoshida, Akira; Ohshima, Takeshi

    2008-01-01

    The effect of 380 keV proton irradiation on the photoluminescence (PL) properties has been investigated for undoped and Eu-doped GaN. As the proton irradiation exceeds 1x10 13 cm -2 , a drastic decrease of PL intensity of the near band-edge emission of undoped GaN was observed. On the other hand, for Eu-doped GaN, the PL emission corresponding to the 5 D 0 → 7 F 2 transition in Eu 3+ kept the initial PL intensity after the proton irradiation up to 1x10 14 cm -2 . Present results, together with our previous report on electron irradiation results, suggest that Eu-doped GaN is a strong candidate for light emitting devices in high irradiation environment

  5. Simulation of RPC performance for 511 keV photon detection

    CERN Document Server

    Lippmann, C; Riegler, W

    2009-01-01

    Measurements of the time resolution of timing Resistive Plate Chambers (RPCs) reveal some differences when comparing the results for 511 keV photons and for particle beams. The subject is of interest, since timing RPCs are currently considered for Positron Emission Tomography (PET), where the sensitivity of the system depends largely on the time resolution of the detector. In this publication we discuss possible explanations, in particular the statistical fluctuations of the deposited charge and the Compton electron flight time distributions. Moreover, we rediscuss the reduction of the Townsend coefficient due to the space charge effect inside the avalanches as a function of the avalanche size. We shall see that the dependence assumed by different analytic models differs significantly from what is predicted by detailed Monte Carlo avalanche simulations.

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

    International Nuclear Information System (INIS)

    Yang, C.; Jamieson, D.N.; Hopf, T.; Tamanyan, G.; Spizziri, P.; Pakes, C.; Andresen, S.E.; Hudson, F.; Gauja, E.; Dzurak, A.; Clark, R.G.

    2005-01-01

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

  7. TEM study of the ion beam induced damage during 14 kev P+ implantation in silicon

    International Nuclear Information System (INIS)

    Rubanov, S.; Tamanyan, G.; Hudson, F.; Jamieson, D.N.; McCallum, J.C.; Prawer, S.

    2005-01-01

    The proposed silicon-based quantum computer architecture comprises an array of phosphorus donor atoms (qubits) positioned with nanometre accuracy beneath the surface of a semiconductor host, using a single ion implantation technique. The average depth of the implanted ions (the projected range R p ), lateral range R p 1, and the distribution of ions about that depth can be approximated as two-dimensional Gaussian with standard deviation ΔR p and ΔR p 1 (lateral straggle). Using transmission electron microscopy (TEM) we studied ion beam induced damage after 14 keV P + implantation in Si. The TEM images allowed us to compare the depth of the amorphous cluster formation to R p , R p 1, ΔR p 1 calculated from SRIM and hence determine evidence for the limitation on the accuracy of the position of the implanted ions imposed by straggling. (author). 4 refs., 3 figs

  8. 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 produces...... rows of dislocation loops all lying parallel to one particular direction. If the aluminium target is quenched from 600 °C and annealed at room temperature prior to irradiation with aluminium ions, the rows of loops are suppressed. The amount of damage observed is considerably less than would...

  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. Differential cross sections for single ionization of H2 by 75-keV proton impact

    International Nuclear Information System (INIS)

    Chowdhury, U.; Schulz, M.; Madison, D. H.

    2011-01-01

    We have calculated triply differential cross sections (TDCS) and doubly differential cross sections (DDCS) for single ionization of H 2 by 75-keV proton impact using the molecular three-body distorted-wave-eikonal initial-state (M3DW-EIS) approach. Previously published measured DDCS (differential in the projectile scattering angle and integrated over the ejected electron angles) found pronounced structures at relatively large angles that were interpreted as an interference resulting from the two-centered potential of the molecule. Theory treating H 2 as atomic H multiplied by a molecular interference factor only predicts the observed structure when assumptions are made about the molecular orientation. Here we apply the M3DW-EIS method, which does not rely on such an ad hoc approach, but rather treats the interference from first principles.

  11. Electronic excitation of Na atom by electron impact

    International Nuclear Information System (INIS)

    Bielschowsky, C.E.; Souza, G.G.B. de; Lucas, C.A.; Nogueira, J.C.

    1988-01-01

    Electronic excitation of the 3s-3p transition in the Na atom was studied by intermediate energy electron impact spectroscopy. Differential Cross Sections (DCS) and Generalized Oscillator Strenghts (GOS) were determined experimentally for 1 KeV electrons. Theoretical results within the First Born Approximation as well as Glauber theory, were also performed. (A.C.A.S.) [pt

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

    International Nuclear Information System (INIS)

    Lobo, G.; Schillebeeckx, P.; Brusegan, A.; Borella, A.; Corvi, F.; Janeva, N.; Volev, K.

    2003-01-01

    The 232 Th(n,γ) neutron capture cross-section is of great importance for accelerator driven reactor (ADS) systems based on the Thorium-Uranium fuel cycle. An analysis of the required nuclear data, reveals that the status of the 232 Th capture data is far from the requested 2 % uncertainty level. Recently 232 Th average capture measurements, between 5-200 keV neutron energy, were performed at the FzK Karlsruhe (DE). A comparison of the measured averaged capture cross section with the evaluated data files shows a reasonable agreement in the neutron energy range above 15 keV. However, discrepancies of up to 40 % at lower neutron energies are observed. The same order of discrepancies is observed when comparing their results with the results obtained by Macklin et al. at ORELA. To clarify these discrepancies we measured at IRMM the average capture cross-section at the GEel LINear Accelerator (GELINA). The measurements were performed at a 14.37 m flight-path using the Time-Of-Flight (TOF) method. The gamma rays, originating from the 232 Th(n,γ) reaction, were detected by a pair of C 6 D 6 -based liquid scintillators applying a pulse-height weighting method. The neutron flux was measured with an ionisation chamber placed at 80 cm before the Thorium sample. This chamber has a cathode loaded with two back-to-back layers of about 40 μg/cm 2 10 B. The sample consisted of a metallic natural thorium disc of 8 cm diameter and 0.5 mm thick, corresponding to a thickness of 1.588 10 -3 at/b. The background for the capture measurements consists of a time independent and time dependent component. The former, mainly produced by the radioactive decay of the sample, was deduced from measurements with a closed beam. The latter was measured by replacing the thorium sample with a 0.5 mm thick 208 Pb sample of the same size. Such a Pb sample has practically the same scattering probability as the thorium sample and has a negligible capture yield. Therefore, the 208 Pb run provides a good

  13. 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.

  14. Study of single-electron excitations by electron microscopy

    International Nuclear Information System (INIS)

    Craven, A.J.; Gibson, J.M.; Howie, A.; Spalding, D.R.

    1978-01-01

    The inelastic scattering of fast electrons by the excitation of L-shell electrons at a stacking fault in silicon has been studied with a scanning transmission electron microscope. It was found that the bright-field stacking fault contrast is preserved in the filtered L-shell-loss signal at 100 eV. This result is discussed in terms of the delocalization of the excitation mechanism. It is concluded that localization effects will typically become significant only for energy transfers greater than 1 keV from a fast electron of energy 80 keV. (author)

  15. 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.

  16. A 60 keV implanter for metals

    International Nuclear Information System (INIS)

    Leutenecker, R.; Ryssel, H.; Zeller, K.-H.; Spoehrle, H.P.

    1985-01-01

    The design and preliminary performance data of a 60 keV high current implanter for the implantation of non-separated ion beams into metals are described. The target chamber accepts samples up to 70 cm in diameter and is equipped with holders to implant ball bearings, axles and other components which have to be rotated during implantation. Samples are mounted on a rugged table which can move up to 35 kg for +-35 cm in the x and y directions. The implanter, including the vacuum system, is completely computer controlled. The ion source is equipped with an oven having a maximum temperature of 1200 0 C and can deliver ion beams of nitrogen as well as different metal ions such as tin and silver with currents up to 10 mA. (Auth.)

  17. Explanation of the 511 keV line. Cascade annihilating dark matter with the {sup 8}Be anomaly

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Lian-Bao [Southwest University of Science and Technology, School of Science, Mianyang (China)

    2018-02-15

    A possible dark matter (DM) explanation about the long-standing issue of the Galactic 511 keV line is explored in this paper. For DM cascade annihilations of concern, a DM pair π{sub d}{sup +}π{sub d}{sup -} annihilates into unstable π{sub d}{sup 0}π{sub d}{sup 0}, and π{sub d}{sup 0} decays into e{sup +}e{sup -} with new interactions suggested by the {sup 8}Be anomaly. Considering the constraints from the effective neutrino number N{sub eff} and the 511 keV gamma-ray emission, a range of DM is obtained, 11.6 keV line. The MeV scale DM may be searched by the DM-electron scattering, and the upper limit set by the CMB s-wave annihilation is derived in DM direct detections. (orig.)

  18. In situ investigation of the surface silvering of late Roman coins by combined use of high energy broad-beam and low energy micro-beam X-ray fluorescence techniques

    Energy Technology Data Exchange (ETDEWEB)

    Romano, F.P., E-mail: romanop@lns.infn.it [IBAM, CNR, Via Biblioteca 4, 95124 Catania (Italy); LNS, INFN, Via S. Sofia 62, 95123 Catania (Italy); Garraffo, S. [ITABC, CNR, Via Salaria km 29.300, 00016 Monterotondo, Roma (Italy); Pappalardo, L. [IBAM, CNR, Via Biblioteca 4, 95124 Catania (Italy); LNS, INFN, Via S. Sofia 62, 95123 Catania (Italy); Rizzo, F. [LNS, INFN, Via S. Sofia 62, 95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, 95123 Catania (Italy)

    2012-07-15

    The compositional analysis of archeological metals performed with the X-ray Fluorescence technique (XRF) provides information on the ancient technology. One of the most interesting case-study concerns the techniques used by Romans for silvering the surface of coins. Different metallurgical processes have been suggested in previous studies. Recently the investigation has been addressed to the mercury-silvering and to its possible use in the mass-production of coins minted during the late period (after 294 AD). In the present paper the non-destructive investigation of the silvering process used for manufacturing the Roman nummi - the important typology of coin introduced by Diocletian in his monetary reform - is approached by the combined use of the standard X-Ray Fluorescence (XRF) and the low energy micro-X-Ray Fluorescence (LE-{mu}XRF) portable methods. The research was focused on the systematic determination of the mercury presence in a large number of samples and on its correlation with silver in the surface of the coins. 1041 Roman nummi belonging to the Misurata Treasure were analyzed in situ, at the Leptis Magna Museum (Al Khums, Libya). The treasure, composed of about 108 thousand silvered coins, gives the unique opportunity to study the Roman coinage in a wide interval of time (about 40 years in the period 294-333 AD) and in almost all the imperial mints operating in the Roman world. - Highlights: Black-Right-Pointing-Pointer Custom-building of a high energy broad-beam and a low energy micro-beam XRF Black-Right-Pointing-Pointer In situ analysis of the silvering methods in late Roman nummi with plated surfaces Black-Right-Pointing-Pointer The broad-beam XRF was applied for the detection of mercury traces in the coin alloy. Black-Right-Pointing-Pointer The low energy micro-XRF was used to scan the surface patina of the coins. Black-Right-Pointing-Pointer The correlation between mercury and silver at the coin surface was evidenced.

  19. 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.

  20. Triple-differential cross sections for target ionization with simultaneous projectile detachment in 200-keV H-+He collisions

    International Nuclear Information System (INIS)

    Ferger, T.; Najjari, B.; Moshammer, R.; Ullrich, J.; Schulz, M.; Fischer, D.

    2007-01-01

    We have performed a kinematically complete experiment for target ionization with simultaneous projectile detachment (TIPD) in 200-keV H - +He collisions. From the data we extracted triple-differential cross sections (TDCSs) for each electron separately. These TDCSs closely resemble corresponding data for single ionization by charged-particle impact. Surprisingly, the contributions from higher-order processes to TIPD, proceeding through two independent interactions of each electron with the core of the respective other collision partner, are found to be somewhat larger than the first-order process proceeding through the electron-electron interaction

  1. LABORATORY MEASUREMENTS COMPELLINGLY SUPPORT A CHARGE-EXCHANGE MECHANISM FOR THE “DARK MATTER” ∼3.5 keV X-Ray LINE

    Energy Technology Data Exchange (ETDEWEB)

    Shah, Chintan; Dobrodey, Stepan; Bernitt, Sven; Steinbrügge, René; López-Urrutia, José R. Crespo [Max-Planck-Institut für Kernphysik, Heidelberg, D-69117 Heidelberg (Germany); Gu, Liyi; Kaastra, Jelle [SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA, Utrecht (Netherlands)

    2016-12-10

    The reported observations of an unidentified X-ray line feature at ∼3.5 keV have driven a lively discussion about its possible dark matter origin. Motivated by this, we have measured the K-shell X-ray spectra of highly ionized bare sulfur ions following charge exchange with gaseous molecules in an electron beam ion trap, as a source of or a contributor to this X-ray line. We produced S{sup 16+} and S{sup 15+} ions and let them capture electrons in collision with those molecules with the electron beam turned off while recording X-ray spectra. We observed a charge-exchange-induced X-ray feature at the Lyman series limit (3.47 ± 0.06 keV). The inferred X-ray energy is in full agreement with the reported astrophysical observations and supports the novel scenario proposed by Gu et al.

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

    International Nuclear Information System (INIS)

    Friedman, P.G.

    1986-01-01

    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 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 14 C at 10 -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 -4 counts/sec and excellent background suppression. With the cyclotron tuned near the 13 CH background peak, to the frequency for 14 C, the detector suppresses the background to 6 x 10 -4 counts/sec. For each 14 C ion the detectors grazing-incidence Al 2 O 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 12 C, 23 Na, 39 K, 41 K, 85 Rb, 87 Rb, and 133 Cs at 5 to 40 keV, and with 36 keV negative 12 C and 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 -7 Torr and be repeatedly exposed to air. The maximum rate is 10/sup 6.4/ ions/sec in pulse counting mode and 10/sup 9.7/ ions/sec in current integrating mode

  3. Electrostatic analysis of 750 keV DC accelerator

    International Nuclear Information System (INIS)

    Kumar, Abhay; Dwivedi, Jishnu; Jana, Arup Ratan

    2011-01-01

    The indigenously developed 750 keV DC accelerator working at RRCAT for the last 5 years uses SF 6 at 6 bar pressure as the insulating gas. The green house potential of this gas is about 22,000 times more than that of CO 2 gas. An electrostatic analysis of this accelerator was performed in order to probe the necessity of using this gas with a very elaborate gas handling system. The DC accelerator is approximated by a 2-D axisymmetric model in ANSYS and voltages were defined at the individual stages of the accelerating tube. The result of the study shows that the present design needs SF 6 gas and the pressure vessel dimensions need to be modified to operate the DC accelerator with environmentally friendly N 2 -CO 2 mixture. This paper presents the methodology of the analysis, discusses the DC accelerator finite element model and presents the results of the analysis. The paper also proposes changes in the DC accelerator design to run the accelerator with N 2 -CO 2 mixture. (author)

  4. 100 keV 10-B+ implantation into poly-(di-n-hexyl silane), (PDHSi)

    International Nuclear Information System (INIS)

    Fink, D.; Mueller, M.; Behar, M.; Papaleo, R.M.

    2006-01-01

    100 keV 10 B + ions were implanted into poly-(di-n-hexyl silane) in different directions at a fluence of 1 x 10 14 cm -2 , and their depth distribution was determined by means of the neutron depth profiling technique. In no case were the projectile ions found to come to rest according to their predicted range profiles. Instead, they are always found to undergo considerable long-range migration. During the irradiation process this motion appears to be radiation-enhanced, and during the subsequent annealing steps one appears to deal with regular thermal diffusion. The implant redistribution is always found to be governed strongly by the self-created damage, insofar as both electronic and nuclear defects in the polymer act as trapping centers. Their population ratio is modified by thermal annealing. The as-implanted redistribution shows a pronounced directional dependence, which essentially is a consequence of the spatial distributions of the electronic and nuclear damage. The changes of the nuclear defect distribution during thermal annealing are studied by a specially developed tomographic method. It is found that boron is preferentially trapped along the irradiation direction, exhibiting quite pronounced prolate (i.e. cigar-like) distributions. This shape is almost unaffected by thermal annealing. (orig.)

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    The PILATUS detector module was characterized in the PTB laboratory at BESSY II comparing modules with 320 μm thick and newly developed 450 μm and 1000 μm thick silicon sensors. Measurements were carried out over a wide energy range, in-vacuum from 1.75 keV to 8.8 keV and in air from 8 keV to 60 keV. The quantum efficiency (QE) was measured as a function of energy and the spatial resolution was measured at several photon energies both in terms of the modulation transfer function (MTF) from edge profile measurements and by directly measuring the point spread function (PSF) of a single pixel in a raster scan with a pinhole beam. Independent of the sensor thickness, the measured MTF and PSF come close to those for an ideal pixel detector with the pixel size of the PILATUS detector (172 × 172 μm 2 ). The measured QE follows the values predicted by calculation. Thicker sensors significantly enhance the QE of the PILATUS detectors for energies above 10 keV without impairing the spatial resolution and noise-free detection. In-vacuum operation of the PILATUS detector is possible at energies as low as 1.75 keV.

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

    Science.gov (United States)

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

    2013-03-01

    The PILATUS detector module was characterized in the PTB laboratory at BESSY II comparing modules with 320 μm thick and newly developed 450 μm and 1000 μm thick silicon sensors. Measurements were carried out over a wide energy range, in-vacuum from 1.75 keV to 8.8 keV and in air from 8 keV to 60 keV. The quantum efficiency (QE) was measured as a function of energy and the spatial resolution was measured at several photon energies both in terms of the modulation transfer function (MTF) from edge profile measurements and by directly measuring the point spread function (PSF) of a single pixel in a raster scan with a pinhole beam. Independent of the sensor thickness, the measured MTF and PSF come close to those for an ideal pixel detector with the pixel size of the PILATUS detector (172 × 172 μm2). The measured QE follows the values predicted by calculation. Thicker sensors significantly enhance the QE of the PILATUS detectors for energies above 10 keV without impairing the spatial resolution and noise-free detection. In-vacuum operation of the PILATUS detector is possible at energies as low as 1.75 keV.

  7. Mechanical design and construction of a 200 mA, 100 keV, DC, negative ion accelerator

    International Nuclear Information System (INIS)

    Purgalis, P.; Anderson, O.A.; Cooper, W.S.; Cummings, C.; Koehler, G.W.; Matuk, C.A.; Wells, R.P.

    1987-01-01

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

  8. Electron emission from Inconel under ion bombardment

    International Nuclear Information System (INIS)

    Alonso, E.V.; Baragiola, R.A.; Ferron, J.; Oliva-Florio, A.

    1979-01-01

    Electron yields from clean and oxidized Inconel 625 surfaces have been measured for H + ,H 2 + ,He + ,O + and Ar + ions at normal incidence in the energy range 1.5 to 40 keV. These measurements have been made under ultrahigh vacuum and the samples were freed of surface contaminants by bombarding with high doses of either 20 keV H 2 + or 30 keV Ar + ions. Differences in yields of oxidized versus clean surfaces are explained in terms of differences in the probability that electrons internally excited escape upon reaching the surface. (author)

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

    International Nuclear Information System (INIS)

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

    1994-01-01

    The energy distributions for 625-keV H + ions transmitted through thin Si single crystals are studied for detailed angular scans through the left-angle 110 right-angle and left-angle 100 right-angle axial as well as the {111} and {110} planar channels. Well-resolved structures in the distributions taken near the left-angle 110 right-angle axial direction are observed. The experimental energy-loss distributions are very well reproduced by a Monte Carlo simulation using the semiclassical approximation model for core electrons and the two-component free-electron-gas model for valence electrons. The best fit to the data is obtained if the model energy losses are scaled up for core electrons and down for valence electrons by several percent. The experimental distributions can also be reproduced by assuming the mean excitation energy for distant collisions of the ion with core electrons equal to 1.4 times the binding energy for a given shell. No significant differences between the distributions obtained using the solid-state and free-atom valence electron densities have been found. The evolution of the distributions for the left-angle 110 right-angle axial scan is discussed in terms of ion trajectories and the flux distribution. Also, the azimuthally averaged mean energy loss is studied as a function of tilt angle with respect to the left-angle 110 right-angle axis

  10. The electron accelerator Ridgetron

    International Nuclear Information System (INIS)

    Hayashizaki, N.; Hattori, T.; Odera, M.; Fujisawa, T.

    1999-01-01

    Many electron accelerators of DC or RF type have been widely used for electron beam irradiation (curing, crosslinking of polymers, sterilization of medical disposables, preservation of food, etc.). Regardless of the acceleration energy, the accelerators to be installed in industrial facilities, have to satisfy the requires of compact size, low power consumption and stable operation. The DC accelerator is realized very compact in the energy under 300 keV, however, it is large to prevent the discharge of an acceleration column in the energy over 300 keV. The RF electron accelerator Ridgetron has been developed to accelerate the continuous beam of the 0.5-10 MeV range in compact space. It is the first example as an electron accelerator incorporated a ridged RF cavity. A prototype system of final energy of 2.5 MeV has been studied to confirm the feasibility at present

  11. Design and fabrication of a Transverse Field Focussing (TFF) 180 keV negative ion accelerator

    International Nuclear Information System (INIS)

    Matuk, C.A.; Anderson, O.A.; Owren, H.M.; Paterson, J.A.; Purgalis, P.

    1985-11-01

    The 180 keV Transverse Field Focussing (TFF) negative ion accelerator described is the final component of a negative ion based neutral beam acceleration system which is being developed as proof-of-principle demonstration of a radiation hardened neutral beamline. The 180 keV beamline consists of: a surface conversion negative ion source, a 80 keV pre-accelerator, a TFF pumping, matching, and transport section, and the 180 keV TFF accelerator presented. This beamline is expected to provide 1 A of H - at 180 keV. In the design of the accelerator, particular importance was given to the rigidity of the accelerator electrode mounting structures and to the electrical isolation of the electrodes along with their related cooling lines. An optical alignment scheme was developed to assemble and to insure precision alignment of the electrodes

  12. Radiation blistering of Nb implanted sequentially with helium ions of different energies (3-500 keV)

    International Nuclear Information System (INIS)

    Guseva, M.I.; Gusev, V.; Krasulin, U.L.; Martinenko, U.V.; Das, S.K.; Kaminsky, M.S.

    1976-01-01

    Cold rolled, polycrystalline niobium samples were irradiated at room temperature with 4 He + ions sequentially at 14 different energies over an energy range from 3 keV--500 keV in steps of 50 keV. The dose for each energy was chosen to give an approximately uniform concentration of helium between the implant depths corresponding to 3 keV and 500 keV. In one set of experiments the irradiations were started at the Kurchatov Institute with 3 keV 4 He + ions and extended up to 80 keV in several steps. Subsequently, the same target area was irradiated with 4 He + ions at Argonne National Laboratory (ANL) starting at 100 keV and increased to 500 keV in steps of 50 keV. Another set of irradiations were started at ANL with 500 keV 4 He + ions and continued with decreasing ion energies to 100 keV. Subsequently, the same area was irradiated at the Kurchatov Institute starting at 80 keV and continued with decreasing ion energies to 3 keV. Both sets of irradiations were completed for two different total doses, 0.5 C cm -2 and 1.0 C cm -2

  13. 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

  14. Differences in the neutralization of 2.4--10 keV Ne+ scattered from the Cu and Au atoms of an alloy surface

    International Nuclear Information System (INIS)

    Buck, T.M.; Wallace, W.E.; Baragiola, R.A.; Wheatley, G.H.; Rothman, J.B.; Gorte, R.J.; Tittensor, J.G.

    1993-01-01

    The neutralization behavior of low-energy Ne + ions scattered from a compositionally ordered Cu 3 Au(100) surface has been studied over a range of incident energy E 0 from 2.4 to 10 keV. Ion fractions of Ne scattered from Cu atoms in the first, or first two, atom layers exhibited a sharp increase setting in at an E 0 of 4--5 keV, reaching 70% at 10 keV for first-layer scattering. Inelastic energy losses, up to 130 eV, and Auger electron emission from Ne scattered from Cu, were also observed at incident energies above 4 keV. Ne scattered from the Au atoms on the same Cu 3 Au(100) surface showed only the usual velocity-dependent Auger and resonance neutralization. An explanation of the Cu results is given in terms of Ne 2s vacancy creation during the close collision of Ne, which is neutralized on the inward path, followed by autoionization on the outward path after scattering into the vacuum. Conversely, Ne cannot approach Au closely enough to form an appropriate inner-shell vacancy. This is due to the higher Coulombic repulsion created by the greater charge of the Au nucleus

  15. 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 ...

  16. Depth distribution of 2-keV helium-ion irradiation-induced cavities in nickel

    International Nuclear Information System (INIS)

    Fenske, G.; Das, S.K.; Kaminsky, M.

    1981-01-01

    Transmission electron microscopy has been used to study the effect of total dose on the depth distribution of cavities (voids or bubbles) in nickel irradiated at 500 0 C with 20-keV 4 He + ions. A transverse sectioning technique allowed us to obtain the entire depth distribution of cavities from a single specimen. The diameter, number density and volume fraction of cavities were measured as a function of depth from micrographs taken from samples sectioned parallel to the direction of the incident beam. Results for the doses at 2.9 x 10 15 and 2.9 x 10 16 ions/cm 2 show an increase in the average cavity diameter, number density and volume fraction with increasing dose. A further increase in dose from 2.9 x 10 16 to 2.9 x 10 17 ions/cm 2 also shows an increase in the average cavity diameter but a decrease in the number density. This observation is interpreted as evidence for the coalescence of cavities. 3 figures, 1 table

  17. An LCLC resonant topology based filament power supply for 300 KeV DC accelerator

    International Nuclear Information System (INIS)

    Kasliwal, A.; Gauttam, V.K.; Banwari, R.; Pandit, T.G.; Thakurta, A.C.

    2013-01-01

    A compact, low energy dc accelerator for industrial applications requiring beam energy in the range of 100 to 300 keV is under development at Raja Ramanna Centre for Advanced Technology, Indore. The accelerator uses an indirectly heated LaB6 disc type filament of 4 mm diameter as an electron emitter which is floating at terminal voltage of the accelerator. A power supply is required to heat the filament for its full range of emission. A high frequency inverter operating at fixed frequency feeds the power to the filament through high frequency transformers and capacitive isolation column. A buck chopper controls the dc bus voltage of the inverter so as to control the terminal voltage of the filament thus controlling the beam current. This paper presents the analysis and design of the filament supply that implements a 40 kHz high order LCLC series parallel resonant inverter that utilizes the reflected capacitance of the HV transformer and capacitive isolation column as its tank circuit component. The operating characteristics and analysis of series resonant (SRC), parallel resonant (PRC) and series parallel (SPRC) resonant converters have been reported for fixed frequency operation. It has been shown that SPRC takes the advantage of both SRC and PRC curtailing their disadvantages. Hence a series parallel LCLC combination has been used as it gives the advantage of low device currents and a better load regulation. (author)

  18. 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.

  19. The decay of 399 KeV isomeric state in 197Pt

    International Nuclear Information System (INIS)

    Soares, J.C.; Melo, A.A.; Gil, F.B.; Dias, H.

    1981-02-01

    The nuclear levels in 197 Pt have been studied from decay of 95.4 min 197 (sup m)Pt. The isomeric state was produced by (n,#betta#) reaction on the enriched 196 Pt. The #betta#-ray spectra have been observed with a hyperpure Ge detector and a large volume Ge(Li) detector. The half lives of the 399 KeV and the 53 KeV states were determined with improved precision. The results are: T1/2 (399 KeV) = 95.41 +- 0.18 min and T1/2(53 KeV) = 16.58 +- 0.17 ns. The g-factor of the 53 Kev 5/2 - state has been measured by the gamma-gamma time differential perturbed angular correlation (TDPAC) method in an external magnetic field of 25,1 kG using the 346 - 53 KeV gamma cascade. The value of g-factor was obtained to be + 0.335 +- 0.010. This result is compared with the known g-factors of the similar states in 195 Pt, and in 197 Hg and 199 Hg and also with the theoretical calculations based on the quasiparticle-phonon coupling scheme. Possibility of using the 346 - 53 KeV gamma cascade in 197 Pt in the future TDPAC studies is discussed. (Author) [pt

  20. Characteristic K-shell x-ray production by protons below 500 keV

    International Nuclear Information System (INIS)

    Wheeler, R.M.; Chaturvedi, R.P.; Zander, A.R.

    1974-01-01

    The total thick target yield of K-shell x-rays produced in Ni by incident protons over the energy range 90 to 415 keV was measured. Similar measurements with 130 to 415 keV protons were made for Ti, Mn, Fe, Cu, and Zn. The East Texas State University 150 keV Cockcroft--Walton accelerator was used to study Ni K-shell x-rays produced by 90 to 150 keV protons. The remaining data were taken with the SUNY College at Cortland 400 keV Van de Graaff generator. The characteristic x-rays were measured with high resolution Si(Li) detectors. Using the most recent values of K-shell fluorescent yields, x-ray ionization cross sections were calculated and compared to theoretical predictions based on the binary encounter approximation (BEA) model. It was found that even though the data were lower than those expected by the BEA theory, they lie on a universal curve. A comprehensive summary of x-ray ionization cross section references covering the proton energy range up to 500 keV is also included. Possible applications of low energy accelerators (E/sub p/ less than or equal to 500 keV) for further experimental work is discussed

  1. Neutron capture cross sections of 69Ga and 71Ga at 25 keV and Epeak = 90 keV

    Science.gov (United States)

    Göbel, Kathrin; Beinrucker, Clemens; Erbacher, Philipp; Fiebiger, Stefan; Fonseca, Micaela; Heftrich, Michael; Heftrich, Tanja; Käppeler, Franz; Krása, Antonin; Lederer-Woods, Claudia; Plag, Ralf; Plompen, Arjan; Reifarth, René; Schmidt, Stefan; Sonnabend, Kerstin; Weigand, Mario

    2017-09-01

    We measured the neutron capture cross sections of 69Ga and 71Ga for a quasi-stellar spectrum at kBT = 25 keV and a spectrum with a peak energy at 90 keV by the activation technique at the Joint Research Centre (JRC) in Geel, Belgium. Protons were provided by an electrostatic Van de Graaff accelerator to produce neutrons via the reaction 7Li(p,n). The produced activity was measured via the γ emission of the product nuclei by high-purity germanium detectors. We present preliminary results.

  2. Radiation effects in zinc oxide: zinc under bombardment with KeV ions

    International Nuclear Information System (INIS)

    Hastings, J.W.L.

    1967-01-01

    The energy loss, light output, depth of deterioration and the deterioration constant have been determined as a function of energy for various atomic projectiles impinging upon samples of a powdered Zn:Zn phosphor at energies below 105 KeV. The energy loss was observed as a reduction in the light output when projectiles traversed thin regions of previously damaged phosphor. The energy losses for heavier projectiles ( 14 N, 40 Ar, 84 Kr), relative to hydrogen, were found to be lower than those predicted for an amorphous stopping medium. The light output for a given projectile was found to be approximately proportional to the amount of energy lost in electronic collisions. When a phosphor is subjected to prolonged bombardment by heavy ions the deterioration depth is fairly well defined and its value was determined by a measurement of the energy loss of a hydrogen beam in traversing the damaged region. The depths are very large, are proportional to the projectile velocity and seem to be determined to a significant degree by electronic stopping. The deterioration constant, C, is a measure of the ability of a projectile to deteriorate a phosphor and its value is proportional to the number of defects introduced in unit distance along the trajectory of the projectile. The constant was determined from measurements of the efficiencies η, and η o , of partly damaged and undamaged phosphor, respectively, using the observed relationship, C (η/η o - 1) n -1 where n is the irradiation dose. The relative magnitudes of the C values for 14 N, 40 Ar were found to be in agreement with measured nuclear energy loss cross sections for these projectiles. (author)

  3. Test facility for the development of 150-keV, multi-megawatt neutral beam systems

    International Nuclear Information System (INIS)

    Haughian, W.; Baker, W.R.; Biagi, L.A.; Hopkins, D.B.

    1975-11-01

    The next generation of CTR experiments, such as the Tokamak Fusion Test Reactor (TFTR), will require neutral-beam injection systems that produce multi-megawatt, 120-keV deuterium-beam pulses of 0.5-second duration. Since present injection systems are operating in the 10- to 40-keV range, an intensive development effort is in progress to meet a 150-keV requirement. The vacuum system and power supplies that make up a test facility to be used in the development of these injectors are described

  4. On the 1285,0 keV; 55-184WW state structure

    International Nuclear Information System (INIS)

    Kupryashkin, V.T.; Muzalev, P.N.; Feoktistov, A.I.

    1977-01-01

    The structure of the 184 W (1285.0 keV; 5 - ) states is discussed. Decay of this level is shown schematically. The data on multiplicities and probabilities of the γ-transitions for the levels 1285.0 keV; 5 - of 184 W and 1621.4 keV; 5 - of 182 W are presented. The transition amplitude parameters are plotted for different probabilities B(E3;5 - → I + ). The relation between the collective transition amplitudes is established. Transition amplitude parameters and their collective and two-particle components, as well as impurity amplitudes of collective excitation wave functions and matrix elements are given

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

    DEFF Research Database (Denmark)

    Rudakovskyi, Anton; Iakubovskyi, Dmytro

    2016-01-01

    Recent reports of a weak unidentified emission line at ~3.5 keV found in spectra of several matter-dominated objects may give a clue to resolve the long-standing problem of dark matter. One of the best physically motivated particle candidate able to produce such an extra line is sterile neutrino...... 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...

  6. Resonance parameters for measured keV neutron capture cross sections

    Energy Technology Data Exchange (ETDEWEB)

    Musgrove, A.R. de L

    1969-05-01

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

  7. Study of an integrated electronic monitor for neutron beams

    International Nuclear Information System (INIS)

    Barelaud, B.; Nexon-Mokhtari, F.; Barrau, C.; Decossac, J.L.; Vareille, J.C.; Sarrabayrouse, G.

    1994-01-01

    Many neutron beams monitors in 10 keV - 50 keV range are perturbed by gamma radiation impact. This new monitor uses two silicon (junction) diodes operating coincidence detection, combined with an electronic threshold to eliminate gamma background noise. The results and analyses presented here only concern feasibility studies. (D.L.)

  8. Study of an integrated electronic monitor for neutron beams

    Energy Technology Data Exchange (ETDEWEB)

    Barelaud, B.; Nexon-Mokhtari, F.; Barrau, C.; Decossac, J.L.; Vareille, J.C. [Limoges Univ., 87 (France); Sarrabayrouse, G. [Centre National de la Recherche Scientifique (CNRS), 31 - Toulouse (France). Lab. d`Automatique et d`Analyse des Systemes

    1994-12-31

    Many neutron beams monitors in 10 keV - 50 keV range are perturbed by gamma radiation impact. This new monitor uses two silicon (junction) diodes operating coincidence detection, combined with an electronic threshold to eliminate gamma background noise. The results and analyses presented here only concern feasibility studies. (D.L.). 11 refs.

  9. 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.

  10. Development of 350 MHz/1000 Watt intermediate power amplifier for 400 keV RFQ accelerator

    International Nuclear Information System (INIS)

    Pande, M.M.; Patel, N.R.; Shinde, K.R.; Rao, M.K.V.; Handu, V.K.

    2005-01-01

    Two numbers of high power RF systems, each delivering around 35 to 40 kW of power at 350 MHz are being developed in BARC. These High Power Amplifiers (HPA) cater to the total need of 70 kW of RF power required by the 400 keV (Deuterium) RFQ accelerator. This RFQ will replace the existing 400 keV DC accelerator of 14 MeV Neutron Generator. The RFQ will accelerate a deuterium beam from 50 keV to 400 keV to impinge upon a tritium target inside a sub critical assembly. Each of these 35 / 40 KW HPA requires a drive power of around 1000 / 1500 Watt respectively. Hence a intermediate power amplifier (IPA) bas been designed to deliver the power of 1000 Watt at the rate of 350 MHz. The paper describes the development of this amplifier

  11. Slowing down of 100 keV antiprotons in Al foils

    Science.gov (United States)

    Nordlund, K.

    2018-03-01

    Using energy degrading foils to slow down antiprotons is of interest for producing antihydrogen atoms. I consider here the slowing down of 100 keV antiprotons, that will be produced in the ELENA storage ring under construction at CERN, to energies below 10 keV. At these low energies, they are suitable for efficient antihydrogen production. I simulate the antihydrogen motion and slowing down in Al foils using a recently developed molecular dynamics approach. The results show that the optimal Al foil thickness for slowing down the antiprotons to below 5 keV is 910 nm, and to below 10 keV is 840 nm. Also the lateral spreading of the transmitted antiprotons is reported and the uncertainties discussed.

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

    International Nuclear Information System (INIS)

    Kostroun, V.O.

    1994-01-01

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

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

    International Nuclear Information System (INIS)

    Bertrand, F.; Grenier, G.; Pornet, J.

    1968-10-01

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

  14. Further measurements of K shell photoelectric cross sections for some elements in the range 26<=Z<=41 at 74 keV. [74. 409 keV

    Energy Technology Data Exchange (ETDEWEB)

    Arora, S K; Allawadhi, K L; Sood, B S [Punjabi Univ., Patiala (India). Dept. of Physics

    1978-12-01

    K shell photoelectric cross sections in elements Fe, Ni, Cu, Zn, As, Se, Br, Sr, Zr and Nb have been measured at 74.409 keV. The targets were irradiated with x radiation and gamma radiation beams. In confirmation with the earlier results, the present results also show fairly good agreement with theory.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  16. Detectors - Electronics

    International Nuclear Information System (INIS)

    Bregeault, J.; Gabriel, J.L.; Hierle, G.; Lebotlan, P.; Leconte, A.; Lelandais, J.; Mosrin, P.; Munsch, P.; Saur, H.; Tillier, J.

    1998-01-01

    The reports presents the main results obtained in the fields of radiation detectors and associated electronics. In the domain of X-ray gas detectors for the keV range efforts were undertaken to rise the detector efficiency. Multiple gap parallel plate chambers of different types as well as different types of X → e - converters were tested to improve the efficiency (values of 2.4% at 60 KeV were reached). In the field of scintillators a study of new crystals has been carried out (among which Lutetium orthosilicate). CdTe diode strips for obtaining X-ray imaging were studied. The complete study of a linear array of 8 CdTe pixels has been performed and certified. The results are encouraging and point to this method as a satisfying solution. Also, a large dimension programmable chamber was used to study the influence of temperature on the inorganic scintillators in an interval from -40 deg. C to +150 deg. C. Temperature effects on other detectors and electronic circuits were also investigated. In the report mentioned is also the work carried out for the realization of the DEMON neutron multidetector. For neutron halo experiments different large area Si detectors associated with solid and gas position detectors were realized. In the frame of a contract with COGEMA a systematic study of Li doped glasses was undertaken aiming at replacing with a neutron probe the 3 He counters presently utilized in pollution monitoring. An industrial prototype has been realised. Other studies were related to integrated analog chains, materials for Cherenkov detectors, scintillation probes for experiments on fundamental processes, gas position sensitive detectors, etc. In the field of associated electronics there are mentioned the works related to the multidetector INDRA, data acquisition, software gamma spectrometry, automatic gas pressure regulation in detectors, etc

  17. Colliding beam studies of electron detachement from H- by multiply-charged ions

    International Nuclear Information System (INIS)

    Melchert, F.; Benner, M.; Kruedener, S.; Schulze, R.; Meuser, S.; Pfaff, S.; Petri, S.; Huber, K.; Salzborn, E.; Presnyakov, L.P.; Uskov, D.B.

    1993-01-01

    Employing the crossed-beams technique, we have investigated electron-detachment processes from H - in collisions with multiply-charged noble gas ions A q+ . Absolute cross sections for single- and double-electron removal have been measured at center-of-mass energies from 50 keV to 200 keV and charge states q up to 8

  18. Double electron transfer in H- + H+ collisions

    International Nuclear Information System (INIS)

    Braeuning, H; Helm, H; Briggs, J S; Salzborn, E

    2007-01-01

    Absolute cross sections for double electron transfer in H - + H + collisions have been measured for center-of-mass energies from 0.5 keV to 12 keV. Clear oscillations in the cross section are observed which are in excellent agreement with earlier measurements at lower energies by Brouillard et al (1979) as well as Peart and Dolder (1979). After an oscillation maximum at 3 keV center-of-mass energy the cross section decreases for increasing energy with no indication of further oscillations

  19. Collision cross sections of N2 by H+ impact at keV energies within time-dependent density-functional theory

    Science.gov (United States)

    Yu, W.; Gao, C.-Z.; Zhang, Y.; Zhang, F. S.; Hutton, R.; Zou, Y.; Wei, B.

    2018-03-01

    We calculate electron capture and ionization cross sections of N2 impacted by the H+ projectile at keV energies. To this end, we employ the time-dependent density-functional theory coupled nonadiabatically to molecular dynamics. To avoid the explicit treatment of the complex density matrix in the calculation of cross sections, we propose an approximate method based on the assumption of constant ionization rate over the period of the projectile passing the absorbing boundary. Our results agree reasonably well with experimental data and semi-empirical results within the measurement uncertainties in the considered energy range. The discrepancies are mainly attributed to the inadequate description of exchange-correlation functional and the crude approximation for constant ionization rate. Although the present approach does not predict the experiments quantitatively for collision energies below 10 keV, it is still helpful to calculate total cross sections of ion-molecule collisions within a certain energy range.

  20. Measurement of the nitrogen total cross section from 0.5 eV to 50 MeV, and analysis of the 433-keV resonance

    International Nuclear Information System (INIS)

    Harvey, J.A.; Hill, N.W.; Larson, N.M.; Larson, D.C.

    1991-01-01

    High-resolution neutron transmission measurements have been made on several thicknesses of nitrogen gas samples from 0.5 eV to 50 MeV at the Oak Ridge Electron Linear Accelerator (ORELA). A preliminary R-matrix analysis has been done for resonances up to 800 keV. An R-matrix analysis of previous data was done by LANL and ENDF/B-VI, including the lowest energy resonance in 14 N at 433 keV. They found a spin of 3/2 (with ell = 1) and a peak cross section of 7.0 b. Analysis of the present data yield a spin of 7/2 (requiring ell ≥ 2) and a peak cross section of 11.5 b for this resonance. These results are important for transport calculations of neutrons through air. Scattering measurements are planned to determine the parity of this resonance. 6 refs., 2 figs

  1. Ab-initio calculation and experimental observation of room temperature ferromagnetism in 50 keV nitrogen implanted rutile TiO2

    Science.gov (United States)

    Luitel, Homnath; Chakrabarti, Mahuya; Sarkar, A.; Dechoudhury, S.; Bhowmick, D.; Naik, V.; Sanyal, D.

    2018-02-01

    Room temperature magnetic properties of 50 keV N4+ ion beam implanted rutile TiO2 have been theoretically and experimentally studied. Ab-initio calculation under the frame work of density functional theory has been carried out to study the magnetic properties of the different possible nitrogen related defects in TiO2. Spin polarized density of states calculation suggests that both Ninst and NO can induce ferromagnetic ordering in rutile TiO2. In both cases the 2p orbital electrons of nitrogen atom give rise to the magnetic moment in TiO2. The possibility of the formation of N2 molecule in TiO2 system is also studied but in this case no significant magnetic moment has been observed. The magnetic measurements, using SQUID magnetometer, results a ferromagnetic ordering even at room temperature for the 50 keV N4+ ion beam implanted rutile TiO2.

  2. Source of monoenergetic electrons for beta dosimetry

    International Nuclear Information System (INIS)

    Graham, C.L.; Elliott, J.H.

    1983-01-01

    We have developed an electron spectrometer which can produce a continuous beam of monoenergetic electrons. The spectrometer uses 20 millicuries of Cs-137 as a source of electrons which can be magnetically focused at the exit port. Various electron energies can be selected by changing the magnetic field. The maximum electron energy and dose rate for the present design are approximately 630 keV and 1.5 rads per hour, respectively

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-03-01

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

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

    International Nuclear Information System (INIS)

    Tavora, L.M.; Gilboy, W.B.; Morton, E.J.

    1998-03-01

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

  5. Design of power oscillator for 500 keV/20 mA Cockroft-Walton high voltage supply

    International Nuclear Information System (INIS)

    Djasiman; Sudjatmoko; Suprapto

    1999-01-01

    A design of power oscillator for Cockroft-Walton high voltage supply was carried out. This high voltage supply would be used as the acceleration voltage supply of an electron beam machine designed to have 500 keV/20 mA capacity. The power oscillator design consisted of output specification, circuit diagram, power supply and oscillator main components determinations. The power oscillator output wave power, voltage and frequency designed according to voltage multiplier input requirements. The design results showed that the circuit was class-c tickler oscillator having an output specification of 12.1 kW, 15 kV and 40 kHz sinus wave. The main component was a ITK 15-2 triode tube. (author)

  6. Effect of dose on the evolution of cavities in 500-KeV 4He+-ion irradiated nickel

    International Nuclear Information System (INIS)

    Fenske, G.; Das, S.K.; Kaminsky, M.; Miley, G.H.

    1979-01-01

    Transmission electron microscopy has been used to investigate the effect of total dose on the depth distribution of cavities (voids or bubbles) in nickel irradiated at 500 0 C with 500-keV 4 He + ions. A transverse sectioning technique, which allows one to obtain the entire depth distribution of cavities and of damage from a single specimen, was utilized. The size, number density and volume fraction of bubbles or voids were measured from the micrographs taken from samples sectioned parallel to the direction of the incident beam. The results for the dose range studied (2 x 10 19 to 1 x 10 21 ions/m 2 ) show that the average cavity diameter, number density, and the volume fraction (i.e., swelling) increases with increasing dose. The peak in the swelling distribution occurs at depths 8 to 15% deeper than the peak in the calculated projected range profile

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  8. Surface damage and gas trapping profile measurements in copper during 20 kev He+ irradiation

    International Nuclear Information System (INIS)

    Terreault, B.; Veilleux, G.

    1980-01-01

    Surface damage due to 20 keV he + irradiation of OFHC Cu was studied by optical and scanning electron microscopy, and by gas trapping profile measurements with proton backscattering and elastic recoil detection. Both annealed (1 h at 773 K) and unannealed Cu were implanted, at 300 K (0.22Tsub(m)) and 500 K(0.37 Tsub(m)), up to fluences of 3 x 10 18 cm -2 . Additional results with thin (1 μm) evaporated films and stressed cold-rolled foils (3 μm) were obtained. At 500 K in bulk OFHC Cu pores and/or large (approx. 1μm) but scattered blisters appear; at 300 K in bulk or thin film Cu blisters are large and abundant. In all these cases a very large (>=1.5 x 10 1 7 cm -2 ) and sudden release of deeply implanted helium takes place, leading to a depleted profile at a depth of about 90 nm (approx. Rsub(p)). In contrast in cold-rolled foils the blisters are small (approx. 0.4 μm) and the profiles are undepleted. These results are explained by fissuration of helium-pressurized cavities. At high fluence blisters disappear, leaving a porous structure at 500 K and a rough micro-relief at 300 K; the helim profiles are flat and very wide (2-3 Rsub(p)). Blister disappearance, absence of flaking, and porous structure are discussed in terms of the width of the profiles and the formation of a helium-saturated, highly damaged (recrystallized), and permeable layer. (orig.)

  9. Slow electron contribution to inelastic reflection anisotropy

    International Nuclear Information System (INIS)

    Podsvirov, O.A.; Kuznetsov, Yu.A.

    1980-01-01

    Investigated is electron contribution with low energy (up to 1 keV) to the anisotropy of electron inelastic reflection (IRE) from silicon monocrystal (111) within 12-50 keV energy range of primary electrons. Experimental data on IRE anisotropy are presented: delay curves for silicon monocrystal, permitting to separate electrons with the energy up to 1 keV, dependences of IRE anisotropy on the energy of primary electrons for the systems - monocrystalline silicon-amorphous silicon film and delay curves for such systems (film thickness varies from 20 to 2000 A). Suggested is a phenomenologic model, permitting to take into account the contribution of slow electrons to IRE anisotropy: it is supposed, that three groups of electrons take part in the formation of the latter: elastic and inelastic reflected electrons, slow electrons, excited by primary electrons and slow electrons, generated by the reverse flow of the scattered electrons. Contribution of electrons, different by origin, to IRE anisotropy is evaluated in accordance with the experimental data on the basis of this model. It is stated, that slow electrons constitute approximately one half of the IRE anisotropy value, the contribution of both groups of slow electrons being approximately equal

  10. Evaluation of cross sections for neutron interactions with {sup 238}U in the energy region between 5 keV and 150 keV

    Energy Technology Data Exchange (ETDEWEB)

    Sirakov, I. [Institute for Nuclear Research and Nuclear Energy, Sofia (Bulgaria); Capote, R.; Trkov, A. [International Atomic Energy Agency, NAPC-Nuclear Data Section, Vienna (Austria); Gritzay, O. [Institute for Nuclear Research, Kyiv (Ukraine); Kim, H.I. [Korea Atomic Energy Research Institute, Nuclear Data Center, Daejeon (Korea, Republic of); Kopecky, S.; Paradela, C.; Schillebeeckx, P. [European Commission, Joint Research Centre, Geel (Belgium); Kos, B. [Jozef Stefan Institute, Ljubljana (Slovenia); Pronyaev, V.G. [Rosatom State Corporation, Atomsrandart, Moscow (Russian Federation)

    2017-10-15

    Cross sections for neutron interactions with {sup 238}U in the energy region from 5 keV to 150 keV have been evaluated. Average total and capture cross sections have been derived from a least squares analysis using experimental data reported in the literature. The resulting cross sections have been parameterised in terms of average resonance parameters maintaining full consistency with results of optical model calculations by using a dispersive coupled channel optical model potential. The average compound partial cross sections have been expressed in terms of transmission coefficients by applying the Hauser-Feshbach statistical reaction theory including width-fluctuations. A generalized single-level representation compatible with the energy-dependent options of the ENDF-6 format has been applied using standard boundary conditions. The results have been transferred into a full ENDF-6 compatible data file. (orig.)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-10-23

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

  12. Cusp shape studies in H+→He collision in the energy range 75-1400 keV: experiment and theory

    International Nuclear Information System (INIS)

    Zavodszky, P.A.; Gulyas, L.; Sarkadi, L.; Vajnai, T.; Szabo, G.; Ricz, S.; Palinkas, J.; Berenyi, D.

    1994-01-01

    The aim of the present study was to measure the double differential cross section (DDCS) for the electron ejection as a function of electron energy at 0 observation angle in H + →He collisions. Having in mind that the experimental and theoretical shape parameters of the DDCS known in the literature are rather scattered, we made a systematic study in the projectile energy range 75-1400 keV. The total electron yield and the shape parameters of the DDCS were determined and compared with the corresponding values from 2nd order OBK, CDW and CDW-EIS theories. A further aim of this work was to check whether the velocity of the projectile and that of the electrons at the maximum of the cusp peak are indeed equal. (orig.)

  13. Spatial distribution of upstream magnetospheric ≥50 keV ions

    Directory of Open Access Journals (Sweden)

    G. C. Anagnostopoulos

    2000-01-01

    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

  14. 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

  15. Energy loss and straggling of 1–50 keV H, He, C, N, and O ions passing through few layer graphene

    International Nuclear Information System (INIS)

    Allegrini, Frédéric; Bedworth, Peter; Ebert, Robert W.; Fuselier, Stephen A.; Nicolaou, Georgios; Sinton, Steve

    2015-01-01

    Highlights: • Evaluation of graphene foils for space plasma instruments. • Energy loss and straggling of keV ions passing through graphene foils. • Lower energy loss than for ultra-thin carbon foils. • Thickness non-uniformity leads to higher straggling. - Abstract: Graphene could be an alternative to amorphous carbon foils, in particular in space plasma instrumentation. The interaction of ions or neutral atoms with these foils results in different effects: electron emission, charge exchange, angular scattering, and energy straggling. We showed in previous studies that (1) the charge exchange properties are similar for graphene and regular carbon foils, and (2) the scattering at low energies (few keVs) is less for graphene than for one of our thinnest practical carbon foils. In this study, we report measurements of the energy loss and straggling of ∼1–50 keV H, He, C, N, and O ions in graphene. We compare graphene and a carbon foil for hydrogen. We provide simple power law fits to the average energy loss, energy straggling, and skewness of the energy distributions. We find the energy loss for ions transiting through graphene to be reduced compared to thin carbon foils but the energy straggling to be larger, which we attribute to the non-uniformity of the graphene foils used in this study

  16. Angular scattering of 1–50 keV ions through graphene and thin carbon foils: Potential applications for space plasma instrumentation

    International Nuclear Information System (INIS)

    Ebert, Robert W.; Allegrini, Frédéric; Fuselier, Stephen A.; Nicolaou, Georgios; Bedworth, Peter; Sinton, Steve; Trattner, Karlheinz J.

    2014-01-01

    We present experimental results for the angular scattering of ∼1–50 keV H, He, C, O, N, Ne, and Ar ions transiting through graphene foils and compare them with scattering through nominal ∼0.5 μg cm −2 carbon foils. Thin carbon foils play a critical role in time-of-flight ion mass spectrometers and energetic neutral atom sensors in space. These instruments take advantage of the charge exchange and secondary electron emission produced as ions or neutral atoms transit these foils. This interaction also produces angular scattering and energy straggling for the incident ion or neutral atom that acts to decrease the performance of a given instrument. Our results show that the angular scattering of ions through graphene is less pronounced than through the state-of-the-art 0.5 μg cm −2 carbon foils used in space-based particle detectors. At energies less than 50 keV, the scattering angle half width at half maximum, ψ 1/2 , for ∼3–5 atoms thick graphene is up to a factor of 3.5 smaller than for 0.5 μg cm −2 (∼20 atoms thick) carbon foils. Thus, graphene foils have the potential to improve the performance of space-based plasma instruments for energies below ∼50 keV

  17. X-radiation /E greater than 10 keV/, H-alpha and microwave emission during the impulsive phase of solar flares.

    Science.gov (United States)

    Vorpahl, J. A.

    1972-01-01

    A study has been made of the variation in hard (E greater than 10 keV) X-radiation, H-alpha and microwave emission during the impulsive phase of solar flares. Analysis shows that the rise-time in the 20-30-keV X-ray spike depends on the electron hardness. The impulsive phase is also marked by an abrupt, very intense increase in H-alpha emission in one or more knots of the flare. Properties of these H-alpha kernels include: (1) a luminosity several times greater than the surrounding flare, (2) an intensity rise starting about 20-30 sec before, peaking about 20-25 sec after, and lasting about twice as long as the hard spike, (3) a location lower in the chromosphere than the remaining flare, (4) essentially no expansion prior to the hard spike, and (5) a position within 6000 km of the boundary separating polarities, usually forming on both sides of the neutral line near both feet of the same tube of force. Correspondingly, impulsive microwave events are characterized by: (1) great similarity in burst structure with 20-32 keV X-rays but only above 5000 MHz, (2) typical low frequency burst cutoff between 1400-3800 MHz, and (3) maximum emission above 7500 MHz.

  18. Enhancement of electron flux by means of diamond membrane

    International Nuclear Information System (INIS)

    Gavrilov, S.A.; Il'ichev, Eh.A.; Poltoratskij, Eh.A.; Rychkov, G.S.; Dzbanovskij, N.N.; Minakov, P.V.; Suetin, N.V.

    2004-01-01

    One investigates into secondary electron emission (SEE) from diamond films made in the form of 2.5-5 μm thickness membranes. SEE is investigated under two modes: the reflection and the streaming ones. SEE coefficient is evaluated on the basis of analysis of behavior of 0.1-30 keV energy electrons in solid material. It is shown that in case of reflection the SEE coefficient may be over 100 at energies equal to 3 keV, while in case of streaming it does not exceed 5 even at 30 keV energy values [ru

  19. Searches for 3.5 keV Absorption Features in Cluster AGN Spectra

    Science.gov (United States)

    Conlon, Joseph P.

    2018-06-01

    We investigate possible evidence for a spectral dip around 3.5 keV in central cluster AGNs, motivated by previous results for archival Chandra observations of the Perseus cluster and the general interest in novel spectral features around 3.5 keV that may arise from dark matter physics. We use two deep Chandra observations of the Perseus and Virgo clusters that have recently been made public. In both cases, mild improvements in the fit (Δχ2 = 4.2 and Δχ2 = 2.5) are found by including such a dip at 3.5 keV into the spectrum. A comparable result (Δχ2 = 6.5) is found re-analysing archival on-axis Chandra ACIS-S observations of the centre of the Perseus cluster.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lawson, Kyle; Zhitnitsky, Ariel, E-mail: klawson@phas.ubc.ca, E-mail: arz@phas.ubc.ca [Department of Physics and Astronomy, University of British Columbia, Vancouver, B.C. V6T 1Z1 (Canada)

    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].

  1. 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.

  2. 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.

  3. H(2s) excitation in 10-100 keV H+ - H collisions

    International Nuclear Information System (INIS)

    Higgins, D.P.; Geddes, J.; Gilbody, H.B.

    1996-01-01

    The authors have used a crossed beam technique to determine cross sections for 2s excitation of H atoms in 10-100 keV collisions. The results extend their previous 4-26 keV measurements to intermediate energies where theoretical predictions based on close coupling methods are known to be strongly dependent on the choice of the expansion basis. The 4-100 keV cross sections exhibit an undulatory structure similar to that predicted by some of the many close coupling calculations but good quantitative agreement is shown to be very limited. Close coupling calculations which employ large basis sets at the expense of target states are shown to agree less satisfactorily with experiment than those which include only the dominant 1s capture channel

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

    International Nuclear Information System (INIS)

    Higaki, Tetsutaro; Takahashi, Fuminobu; Tokyo Univ., Kashiwa

    2014-03-01

    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 a ≅ 7 keV and the decay constant f a ≅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.

  5. 7 keV sterile neutrino dark matter from split flavor mechanism

    International Nuclear Information System (INIS)

    Ishida, Hiroyuki; Takahashi, Fuminobu; Tokyo Univ., Kashiwa

    2014-02-01

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

  6. Electron and Positron Stopping Powers of Materials

    Science.gov (United States)

    SRD 7 NIST Electron and Positron Stopping Powers of Materials (PC database for purchase)   The EPSTAR database provides rapid calculations of stopping powers (collisional, radiative, and total), CSDA ranges, radiation yields and density effect corrections for incident electrons or positrons with kinetic energies from 1 keV to 10 GeV, and for any chemically defined target material.

  7. Dose calculation due to electrons interaction with DNA

    Energy Technology Data Exchange (ETDEWEB)

    Mark, S; Orion, I; Shani, G [Ben-Gurion Univ. of the Negev, Beersheba (Israel). Dept. of Nuclear Engineering; Laster, B [Brookhaven National Lab., Upton, NY (United States)

    1996-12-01

    Experiments done with gadolinium loaded V79 Chinese Hamster cells, irradiated with thermal neutrons, showed that cells lethality increased by a factor of 1.8 compared to the case where the Gd atoms were located outside the cell.(l) It was obvious that the dramatic increase in cell lethality is due to the emission of Auger electrons following the {sup 157}Gd(n,{gamma}){sup 158}Gd reaction. Electrons of various energies from about 40 keV (very few) to less than 1 keV, are emitted. In the present work, energy absorbed in DNA was calculated, due to interaction of electron of different energies: 30, 15, 10, 8, 5 and 2 keV. The Monte Carlo code EGS4(2) was used for the calculations. The DNA was modeled as a series of alternative layers of sugar (phosphate - C{sub 5}O{sub 5}H{sub 7}P p=1.39gr cm{sup -1}) and water. The sugar layer thickness was assumed 2.5nm and the water layer thickness 10nm. An isotropic electron source was assumed to be located in a water layer and the electrons interactions (absorption and scattering) were calculated in the forward hemisphere. The energy absorbed in a group of 8 layers, (4 sugar and 4 water) was calculated for each one of the electron energies. An interesting fact found in those calculations; when the source electrons energy is 10 keV or more, most of the electrons are absorbed in the DNA-water system, are at energy about 2keV. There is no good explanation for this phenomenon except for assuming that when the electron`s energy reaches a low point of about 2keV, it cannot escape absorption in the medium. 10% of the 10 keV electrons deposit their entire energy in the 8 layers range (authors).

  8. Electronic sputtering

    International Nuclear Information System (INIS)

    Johnson, R.E.

    1989-01-01

    Electronic sputtering covers a range of phenomena from electron and photon stimulated desorption from multilayers to fast heavy ion-induced desorption (sputtering) of biomolecules. In this talk the author attempted. Therefore, to connect the detailed studies of argon ejection from solid argon by MeV ions and keV electrons to the sputtering of low temperatures molecular ices by MeV ions then to biomolecule ejection from organic solids. These are related via changing (dE/dx) e , molecular size, and transport processes occurring in materials. In this regard three distinct regions of (dE/dx) e have been identified. Since the talk this picture has been made explicit using a simple spike model for individual impulsive events in which spike interactions are combined linearly. Since that time also the molecular dynamics programs (at Virginia and Uppsala) have quantified both single atom and dimer processes in solid Ar and the momentum transport in large biomolecule sputtering. 5 refs

  9. 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.

  10. 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...

  11. Measurement of 24.3 keV activation cross sections with the iron filter technique

    International Nuclear Information System (INIS)

    Rimawi, K.; Chrien, R.E.

    1975-01-01

    By using high-resolution detection techniques, intensities of specific activation lines from 197 Au(n,gamma), 238 U(n,gamma), 127 I(n,gamma), and 115 In(n,gamma) [54 min + 2.2 sec] were recorded, by using the BNL HFBR iron-filtered neutron beam. From a com- parison with the reaction 10 B(n,αgamma), cross sections at 24.3 keV were determined. (24.3 keV neutron activation cross sections, relative 10 B standard). (4 figures) (U.S.)

  12. K X-Ray production cross sections for 40-180 keV protons

    International Nuclear Information System (INIS)

    Szegedi, S.; Hassan, M.F.

    2002-01-01

    In view of the importance of the X-ray production cross-section for the determination of element concentration in a given material, we have measured them experimentally for light elements Sc and Fe using proton beams of energy between 40 and 180 keV. The obtained K X-ray production cross-section is compared with the previous experimental results. The experimental K X-ray production cross-section for proton induced X-ray emission (PIXE) analysis, using low energy (200 keV) accelerator, have been improved

  13. 17 keV and 30 eV Dirac neutrinos and a techniphoton

    International Nuclear Information System (INIS)

    Holdom, B.

    1985-01-01

    We consider four flavors of left-handed Weyl neutrinos forming two Dirac masses, of order 17 keV and 30 eV. The symmetry Lsub(e)+Lsub(tau)-Lsub(μ)-Lsub(lambda) ensures this form of the mass matrix and consistency with experiments. We show how it arises in a technicolor context. The structure of the model can incorporate a techniphoton, an unbroken U(1) gauge symmetry of technifermions, and this makes a 17 keV neutrino cosmologically unstable. (orig.)

  14. The study of the ion beam induced swelling in crystalline germanium irradiated by a 30 keV Ga+ focused ion beam

    International Nuclear Information System (INIS)

    Rubanov, S.; Munroe, P.R.; Stevens-Kalceff, M.

    2005-01-01

    The effect of swelling of crystalline Ge irradiated at room temperature with 30 keV Ga + focused ion beam (FIB) was studied by means of in situ FIB imaging, atomic force microscopy (AFM) and transmission electron microscopy (TEM). The swelling occurred in the surface region of amorphous damage layer which was formed during ion irradiation. The degree of swelling reaches values up to 10 times for an implantation dose of ∼10 17 ions/cm 2 . Cross-secitonal TEM examination showed that the swelling is due to formation of a porous layer with a honeycomb structure. (author). 8 refs., 4 figs

  15. A Monte Carlo computer code for evaluating energy loss of 10 keV to 10 MeV ions in amorphous silicon materials

    International Nuclear Information System (INIS)

    Erramli, H.; Elbounagui, O.; Misdaq, M.A.; Merzouki, A.

    2007-01-01

    The basic concepts of a computer simulation code for determining the energy loss of ions in the 10 keV to 10 MeV energy range in amorphous silicon materials were presented and discussed. Data obtained were found in good agreement with those obtained by using a SRIM programme. Electronic and nuclear energy losses were evaluated. Variation of the energy loss as a function of the incident ion energy were studied. This new computer code is a good tool for evaluating stopping powers of various materials for light and heavy ions

  16. Measurement of the ratio of double-to-single photoionization of helium at 2.8 keV using synchrotron radiation

    International Nuclear Information System (INIS)

    Levin, J.C.; Lindle, D.W.; Keller, N.; Miller, R.D.; Azuma, Y.; Mansour, N.B.; Berry, H.G.; Sellin, I.A.

    1991-01-01

    We report the first measurement of the ratio of double-to-single photoionization of helium well above the double-ionization threshold. Using a time-of-flight technique, we find He ++ /He + =1.6±0.3% at hν=2.8 keV. This value lies between calculations by Amusia (2.3%) and by Samson, who predicts 1.2% by analogy with electron-impact ionization cross sections of singly charged ions. Good agreement is obtained with older shake calculations of Byron and Joachain, and of Aberg, who predict 1.7%

  17. 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)

  18. Measurement of L-shell photoelectric cross sections in high Z elements at 37 and 74 keV

    Energy Technology Data Exchange (ETDEWEB)

    Allawadhi, K L; Ghumman, B S; Sood, B S [Punjabi Univ., Patiala (India). Nuclear Science Labs.

    1977-05-01

    L-shell photoelectric cross section measurements have been made at 36.818 and 74.409 keV for four elements in the range 81<=Z<=92. The measurements at 74.409 keV are found to agree with theory, within experimental uncertainties, but the experimental values at 36.818 keV are found to be higher than the theoretical predictions. The possible reasons for the observed discrepancy are discussed.

  19. "Trampoline" ejection of organic molecules from graphene and graphite via keV cluster ions impacts

    Science.gov (United States)

    Verkhoturov, Stanislav V.; Gołuński, Mikołaj; Verkhoturov, Dmitriy S.; Geng, Sheng; Postawa, Zbigniew; Schweikert, Emile A.

    2018-04-01

    We present the data on ejection of molecules and emission of molecular ions caused by single impacts of 50 keV C602+ on a molecular layer of deuterated phenylalanine (D8Phe) deposited on free standing, 2-layer graphene. The projectile impacts on the graphene side stimulate the abundant ejection of intact molecules and the emission of molecular ions in the transmission direction. To gain insight into the mechanism of ejection, Molecular Dynamic simulations were performed. It was found that the projectile penetrates the thin layer of graphene, partially depositing the projectile's kinetic energy, and molecules are ejected from the hot area around the hole that is made by the projectile. The yield, Y, of negative ions of deprotonated phenylalanine, (D8Phe-H)-, emitted in the transmission direction is 0.1 ions per projectile impact. To characterize the ejection and ionization of molecules, we have performed the experiments on emission of (D8Phe-H)- from the surface of bulk D8Phe (Y = 0.13) and from the single molecular layer of D8Phe deposited on bulk pyrolytic graphite (Y = 0.15). We show that, despite the similar yields of molecular ions, the scenario of the energy deposition and ejection of molecules is different for the case of graphene due to the confined volume of projectile-analyte interaction. The projectile impact on the graphene-D8Phe sample stimulates the collective radial movement of analyte atoms, which compresses the D8Phe layer radially from the hole. At the same time, this compression bends and stretches the graphene membrane around the hole thus accumulating potential energy. The accumulated potential energy is transformed into the kinetic energy of correlated movement upward for membrane atoms, thus the membrane acts as a trampoline for the molecules. The ejected molecules are effectively ionized; the ionization probability is ˜30× higher compared to that obtained for the bulk D8Phe target. The proposed mechanism of ionization involves tunneling of

  20. "Trampoline" ejection of organic molecules from graphene and graphite via keV cluster ions impacts.

    Science.gov (United States)

    Verkhoturov, Stanislav V; Gołuński, Mikołaj; Verkhoturov, Dmitriy S; Geng, Sheng; Postawa, Zbigniew; Schweikert, Emile A

    2018-04-14

    We present the data on ejection of molecules and emission of molecular ions caused by single impacts of 50 keV C 60 2+ on a molecular layer of deuterated phenylalanine (D8Phe) deposited on free standing, 2-layer graphene. The projectile impacts on the graphene side stimulate the abundant ejection of intact molecules and the emission of molecular ions in the transmission direction. To gain insight into the mechanism of ejection, Molecular Dynamic simulations were performed. It was found that the projectile penetrates the thin layer of graphene, partially depositing the projectile's kinetic energy, and molecules are ejected from the hot area around the hole that is made by the projectile. The yield, Y, of negative ions of deprotonated phenylalanine, (D8Phe-H) - , emitted in the transmission direction is 0.1 ions per projectile impact. To characterize the ejection and ionization of molecules, we have performed the experiments on emission of (D8Phe-H) - from the surface of bulk D8Phe (Y = 0.13) and from the single molecular layer of D8Phe deposited on bulk pyrolytic graphite (Y = 0.15). We show that, despite the similar yields of molecular ions, the scenario of the energy deposition and ejection of molecules is different for the case of graphene due to the confined volume of projectile-analyte interaction. The projectile impact on the graphene-D8Phe sample stimulates the collective radial movement of analyte atoms, which compresses the D8Phe layer radially from the hole. At the same time, this compression bends and stretches the graphene membrane around the hole thus accumulating potential energy. The accumulated potential energy is transformed into the kinetic energy of correlated movement upward for membrane atoms, thus the membrane acts as a trampoline for the molecules. The ejected molecules are effectively ionized; the ionization probability is ∼30× higher compared to that obtained for the bulk D8Phe target. The proposed mechanism of ionization involves

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

    International Nuclear Information System (INIS)

    Kostroun, V.O.

    1987-01-01

    Interest in interactions of low energy highly charged ions with electrons, atoms or ions is due to their importance to controlled thermonuclear fusion research and the interesting nature of the fundamental processes involved. Studies of such interactions have long been hampered by a lack of suitable ions sources. A superconducting solenoid, cryogenic Electron Beam Ion Source, CEBIS, has been constructed at Cornell University to produce low energy very highly charged ions. At present, using a pulsed 0.5A,8.5 keV electron beam, the source is capable of producing highly charged ions of C,N,O, including bare nuclei, and ions of Ar up to charge state 11 + in 1 millisecond of confinement time. The source is being used in experiments to investigate charge transfer and accompanying processes in low energy, highly charged ion-atom collisions

  2. A Study of the 384 KeV Complex Gamma Emission from Plutonium-239

    International Nuclear Information System (INIS)

    Forsyth, R.S.; Ronqvist, N.

    1965-11-01

    Plutonium-239 has been reported to emit a gamma of energy 384 KeV. Subsequent workers, using radiation of this energy as a nondestructive measure of the plutonium content of various materials, found that the peak obtained by sodium iodide scintillation spectrometry showed a pronounced shoulder at about 330 KeV. This shoulder has been attributed to protactinium-233 and to uranium-237. From the width of the peak, however, it is obvious that at least three contributors are present. The present paper describes gamma spectrometric studies of plutonium samples of several isotopic compositions using a sodium iodide detector and a lithium-drifted germanium detector. The 384 KeV peak has been shown to be a complex peak containing 12 gamma components due to plutonium-239 between 300 - 450 KeV, and their relative intensities have been estimated. Anion exchange and solvent extraction experiments have also demonstrated that two further contributions due to uranium-237 are present in plutonium containing significant amounts of plutonium-241

  3. POLARIZED-LIGHT EMISSION IN KEV HE2++NA(3S) COLLISIONS

    NARCIS (Netherlands)

    BODUCH, P; VANBUCHEM, J; BLIEK, FW; HOEKSTRA, R; MORGENSTERN, R; OLSON, RE

    1995-01-01

    We investigated l and m-distributions of He II (n = 4) states formed during 2-13.3 keV amu(-1) He2+ + Na(3s) collisions by measuring profiles and the linear polarization of the He II (4 --> 3) emission. We found that at these energies capture into He+(4f) dominates over capture into other He+(4l)

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

    International Nuclear Information System (INIS)

    Derrien, H.; de Saussure, G.; Perez, R.B.; Larson, N.M.; Macklin, R.L.

    1986-06-01

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

  5. Atomic mixing effects on high fluence Ge implantation into Si at 40 keV

    International Nuclear Information System (INIS)

    Gras-Marti, A.; Jimenez-Rodriguez, J.J.; Peon-Fernandez, J.; Rodriguez-Vidal, M.; Tognetti, N.P.; Carter, G.; Nobes, M.J.; Armour, D.G.

    1982-01-01

    Ion implanted profiles of 40 keV Ge + into Si at fluences ranging from approx. equal to 10 15 ions/cm 2 up to saturation have been measured using the RBS technique. The profiles compare well with the predictions of an analytical model encompasing sputter erosion plus atomic relocation. (orig.)

  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

    -derived optical constants, which we determined from reflectance-vs-incidence angle measurements also made using synchrotron radiation, in the range E=120 - 180 keV. We describe our experimental investigation in detail, compare the new W/SiC multilayers with both W/Si and W/B4C films that have been studied......We have developed a new depth-graded multilayer system comprising W and SiC layers, suitable for use as hard X-ray reflective coatings operating in the energy range 100 - 200 keV. Grazing incidence X-ray reflectance at E=8 keV was used to characterize the interface widths, as well as the temporal...... 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. 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

    optical constants, which we determined from reflectance versus incidence angle measurements also made using synchrotron radiation, in the range E = 120-180 keV. We describe our experimental investigation in detail, compare the new W/SiC multilayers with both W/Si and W/B4C films that have been studied......We have developed a new depth-graded multilayer system comprising W and SiC layers, suitable for use as hard x-ray reflective coatings operating in the energy range 100-200 keV. Grazing-incidence x-ray reflectance at E = 8 keV was used to characterize the interface widths, as well as the temporal...... 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...

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

    Energy Technology Data Exchange (ETDEWEB)

    Pareschi, G.; Pasqualini, G. [Ferrara, Univ. (Italy). Dipt. di Fisica; Frontera, F. [CNR, Bologna (Italy). Istituto di TESRE]|[Ferrara, Univ. (Italy). Dipt. di Fisica

    1997-09-01

    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. They present recent results obtained from their group regarding the possible use of Bragg-diffraction technique to design hard X-ray focusing telescopes.

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

    International Nuclear Information System (INIS)

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

    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. They present recent results obtained from their group regarding the possible use of Bragg-diffraction technique to design hard X-ray focusing telescopes

  10. 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.; hide

    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.

  11. A Study of the 384 KeV Complex Gamma Emission from Plutonium-239

    Energy Technology Data Exchange (ETDEWEB)

    Forsyth, R S; Ronqvist, N

    1965-11-15

    Plutonium-239 has been reported to emit a gamma of energy 384 KeV. Subsequent workers, using radiation of this energy as a nondestructive measure of the plutonium content of various materials, found that the peak obtained by sodium iodide scintillation spectrometry showed a pronounced shoulder at about 330 KeV. This shoulder has been attributed to protactinium-233 and to uranium-237. From the width of the peak, however, it is obvious that at least three contributors are present. The present paper describes gamma spectrometric studies of plutonium samples of several isotopic compositions using a sodium iodide detector and a lithium-drifted germanium detector. The 384 KeV peak has been shown to be a complex peak containing 12 gamma components due to plutonium-239 between 300 - 450 KeV, and their relative intensities have been estimated. Anion exchange and solvent extraction experiments have also demonstrated that two further contributions due to uranium-237 are present in plutonium containing significant amounts of plutonium-241.

  12. Design of a continuously operated 1-keV deuterium-ion extractor

    International Nuclear Information System (INIS)

    Fink, J.H.

    1978-01-01

    A novel grid structure that is cooled only by radiation and conduction is shown to be capable of continuously extracting 2.5 kA.m -2 of 1-keV positive deuterium ions while dissipating a power loading of 0.4 MW.m -2

  13. Perturbation of angular correlations of 180-86 keV cascade in sup(155)G

    International Nuclear Information System (INIS)

    Budzynski, M; Lebedev, N.A.; Ljzurej, G.; Nezgoda, Kh.; Kochetov, O.I.; Muminov, A.I.; Khazratov, T.

    1980-01-01

    Using the differential disturbed angular correlation method attenuation of a correlation of the 180-86 keV cascade directions in 155 Gd has been studied. Coefficients of integral angular γγ-correlations for 155 Gd have been measured by an automatic correlation spectrometer with a Ge(Li) and two NaI(Tl) detectors. The obtained correlation coefficients are listed in a table. A fragment of the 155 Tb decay scheme, delayed-coincidence curves and a γ-spectrum are presented. During the analysis of experimental data on the differential disturbed angular correlation the nondisturbed correlation coefficient A 22 (O)=-0.220(4) for the 180-86 keV cascade has been obtained. Basing on this result the multipole composition of the 180 keV transition has been determined: M1+(3.54)% E2 with the mixing ratio delta=0.188. It has been found that at a low temperature strong attenuation of the 180-86 keV cascade angular correlation has been observed [ru

  14. 8 to 11 keV x-ray sources for imaging and absorption experiments

    International Nuclear Information System (INIS)

    Molitoris, J.D.; Phillion, D.W.; Osterheld, A.L.; Stewart, R.E.; Rothman, S.D.

    1992-01-01

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

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  16. 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.

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

    Science.gov (United States)

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

    2014-12-01

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

  18. Synthesis of Au nanoparticles at the surface and embedded in carbonaceous matrix by 150 keV Ar ion irradiation

    International Nuclear Information System (INIS)

    Prakash, Jai; Tripathi, Jalaj; Tripathi, A; Kumar, P; Asokan, K; Avasthi, D K; Rigato, V; Pivin, J C; Chae, Keun Hwa; Gautam, Sanjeev

    2011-01-01

    We report on synthesis of spherical Au nanoparticles at the surface and embedded in carbonaceous matrix by 150 keV Ar ion irradiation of thin Au film on polyethyleneterepthlate (PET). The pristine and irradiated samples are characterized by Rutherford backscattering spectrometry (RBS), atomic force microscopy, scanning electron microscopy and transmission electron microscopy (TEM) techniques. RBS spectra reveal the sputtering of Au film and interface mixing, increasing with increasing fluence. Surface morphology shows that at the fluence of 5 x 10 15 ions cm -2 , dewetting of thin Au film begins and partially connected nanostructures are formed whereas, at the higher fluence of 5 x 10 16 ions cm -2 , isolated spherical Au nanoparticles (45 ± 20 nm) are formed at the surface. Cross-sectional TEM observations also evidence the Au nanoparticles at the surface and mixed metal-polymer region indicating the formation of nanocomposites with small Au nanoparticles. The results are explained by the crater formation, sputtering followed by dewetting of the thin Au film and interdiffusion at the interface, through molten zones due to thermal spike induced by Ar ions.

  19. Development status of a test stand for semiconductor photocathodes with 60 keV spin-polarized beamline

    Energy Technology Data Exchange (ETDEWEB)

    Kurichijanil, Neeraj; Enders, Joachim; Espig, Martin; Fritzsche, Yuliya; Heichelt, Dominic; Kaiser, Andreas; Roesch, Heidi; Wagner, Markus [Institut fuer Kernphysik, TU Darmstadt (Germany)

    2016-07-01

    A test facility for Photo-Cathode Activation, Test and Cleaning using atomic-Hydrogen (Photo-CATCH) is being constructed at TU Darmstadt's Institute for Nuclear Physics (IKP) which houses the Superconducting Darmstadt Linear Accelerator (S-DALINAC). In order to improve the performance of the SDALINAC's photoelectron source based on GaAs, systematic studies in terms of quantum efficiency (QE), cathode rejuvenation, lifetimes and polarization (P) have to be conducted on different photocathode types. These factors strongly depend on handling of the cathode, the vacuum condition in the chambers, cathode surface cleaning as well as preservation of stoichiometry, negative electron affinity (NEA) activation of the cathode and the type and structure of the semiconductor material. With Photo-CATCH, experiments such as atomic-hydrogen cleaning, multi-alkali and oxidant NEA activation of the cathode and tests of QE, P and lifetimes can be performed in an improved vacuum. Additionally, experiments with polarized-electron beams of up to 60 keV are foreseen.

  20. Influence of ionic parameters on Auger emission by aluminium, induced by medium energy ions (2 to 5 keV)

    International Nuclear Information System (INIS)

    Celier, Dominique

    1987-01-01

    This research thesis reports the study of excitation collision mechanisms of metal atoms under irradiation by electrons with energy lower than or equal to 5 keV. After having outlined why this energy range is interesting, and indicated the different aluminium single crystals used in this study, the author describes the main involved emission phenomena related to the series of collisions due to emissions of different particles (electrons, photons, neutral or ionized atoms, backscattered primary ions). In the second part, the author recalls the characteristics of an Auger emission induced by ionic bombardment. Then, he presents the experimental installation which has been calibrated in order to allow the comparison of spectra induced under irradiations with different characteristics. Experimental results are reported and discussed. The cascade of binary shocks has also been examined. The scattering integral has been computed for several simple cases of collision, and allowed the definition of different conditions of excitation and ejection of excited atoms, depending on the fact that the ionizing shock is asymmetric or symmetric [fr

  1. Charge changing and excitation cross sections for 1-25 KeV hydrogen ions and atoms incident on sodium

    International Nuclear Information System (INIS)

    Howald, A.M.

    1983-01-01

    Measurements of charge changing and excitation cross sections for 1-25 keV beams of hydrogen atoms and ions incident on a sodium vapor target are reported. The charge changing cross sections are for reactions in which the incident H ion or atom gains or loses an electron during a collision with a Na atoms to form a hydrogen ion or atom in a different charge state. The six cross sections measured are sigma/sub +0/ and sigma/sub +-/ for incident protons, sigma/sub -0/ and sigma/sub -+/ for incident H - ions, and sigma/sub g-/ and sigma/sub g+/ for incident H(1s) atoms. Measurements are also reported for the negative, neutral, and positve equilibrium fractions for H beams in thick Na targets. The excitation cross sections are for reactions in which the Na target atom is excited to the 3p level by a collision with a H atom or ion. The five cross sections measured are for incident H + , H 2 + , H 3 + , and H - ions, and for H(1s) atoms. These cross sections are measured using a new technique that compares them directly to the known cross section for excitation by electron impact

  2. Absolute disintegration rate and 320 keV {gamma}-ray emission probability of {sup 51}Cr

    Energy Technology Data Exchange (ETDEWEB)

    Almeida, M.C.M. de [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes /Instituto de Radioprotecao e Dosimetria (LNMRI/ IRD), Avenida Salvador Allende, s/no. Recreio-Rio de Janeiro, CEP 22780-160 (Brazil)], E-mail: candida@ird.gov.br; Iwahara, A.; Poledna, R.; Silva, C.J. da; Delgado, J.U. [Laboratorio Nacional de Metrologia das Radiacoes Ionizantes /Instituto de Radioprotecao e Dosimetria (LNMRI/ IRD), Avenida Salvador Allende, s/no. Recreio-Rio de Janeiro, CEP 22780-160 (Brazil)

    2007-09-21

    This work describes the procedures for determining absolutely the {sup 51}Cr disintegration rate by using the 4{pi}{beta}-{gamma} coincidence and anti-coincidence counting and the sum-peak methods. A 4''x4''-NaI(Tl) scintillation detector was used in the {gamma}- channel of the 4{pi}{beta}-{gamma} coincidence system for {gamma}-ray counting. In the {beta}-channel, a 4{pi} gas flow proportional counter was used for counting of characteristic X-rays and Auger electrons originating from the electron capture events of the {sup 51}Cr decay scheme. Gamma spectrometry measurements by high-pure planar and coaxial germanium detectors were performed in the sum-peak method and in the determination of the 320 keV {gamma}-emission probability of {sup 51}Cr. This latter determined value agrees with the recent values found in the literature, confirming the reliability of the three methods used in this work for the disintegration rate measurements.

  3. Structural and optical modification in 4H-SiC following 30 keV silver ion irradiation

    Science.gov (United States)

    Kaushik, Priya Darshni; Aziz, Anver; Siddiqui, Azher M.; Lakshmi, G. B. V. S.; Syväjärvi, Mikael; Yakimova, Rositsa; Yazdi, G. Reza

    2018-05-01

    The market of high power, high frequency and high temperature based electronic devices is captured by SiC due to its superior properties like high thermal conductivity and high sublimation temperature and also due to the limitation of silicon based electronics in this area. There is a need to investigate effect of ion irradiation on SiC due to its application in outer space as outer space is surrounded both by low and high energy ion irradiations. In this work, effect of low energy ion irradiation on structural and optical property of 4H-SiC is investigated. ATR-FTIR is used to study structural modification and UV-Visible spectroscopy is used to study optical modifications in 4H-SiC following 30 keV Ag ion irradiation. FTIR showed decrease in bond density of SiC along the ion path (track) due to the creation of point defects. UV-Visible absorption spectra showed decrease in optical band gap from 3.26 eV to 2.9 eV. The study showed degradation of SiC crystallity and change in optical band gap following low energy ion irradiation and should be addressed while fabricationg devices based on SiC for outer space application. Additionally, this study provides a platform for introducing structural and optical modification in 4H-SiC using ion beam technology in a controlled manner.

  4. In situ thin film measurement by X-rays induced by 10 KeV-100 KeV ion beams

    International Nuclear Information System (INIS)

    Torrisi, L.; Calcagno, L.; Trovato, A.; Foti, G.

    1982-01-01

    The in situ measurement of thin film thickness between 50 and 100 KeV is described. The method used seems to be flexible enough and can be applied to any type of material. The only parameter intervening in the thickness measurement is the specific energy loss of the proton beams. Film of Al, Cu and Ag have been considered. When the primary beam energy increases the perception in depth of the method grows, reaching 10 μm with 1 MeV beam. In this case the autoabsorption takes place

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

    International Nuclear Information System (INIS)

    Hilgers, G.; Bahar-Gogani, J.; Wickman, G.

    2002-01-01

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

  6. Electron-irradiation-induced phase transformation in alumina

    International Nuclear Information System (INIS)

    Chen, C.L.; Arakawa, K.; Lee, J.-G.; Mori, H.

    2010-01-01

    In this study, electron-irradiation-induced phase transformations between alumina polymorphs were investigated by high-resolution transmission electron microscopy. It was found that the electron-irradiation-induced α → κ' phase transformation occurred in the alumina under 100 keV electron irradiation. It is likely that the knock-on collision between incident electrons and Al 3+ cations is responsible for the occurrence of electron-irradiation-induced phase transformation from α-alumina to κ'-alumina.

  7. A Study of the 190 keV Transition in {sup 141}La

    Energy Technology Data Exchange (ETDEWEB)

    Berg, V; Hoeglund, Aa [Inst. of Physics, Univ. of Stockholm (Sweden); [AB Atome nergi, Nykoping (Sweden); Fogelberg, B [Inst. of Physics, Uppsala Univ. (Sweden)

    1970-05-15

    The gamma-ray spectrum from the decay of 18 min 141 Ba has been studied. Seventeen transitions were found below 900 keV, with energies and (intensities) as follows: 112.9{+-}0.2(3.0), 163.1{+-}0.3 (1.0), 165.7{+-}0.4(0.7), 180.5{+-}0.2(0.9), 190.3{+-}0.1(100), 276.9{+-}0.1 (52.2), 304.2{+-}0.1(55.8), 343.6{+-}0.1(30.8), 364.4{+-}0.6(1.6), 389.7{+-}0.2(2.8), 457.7{+-}0.2(10.4), 462.3{+-}0.2(10.5), 467.3{+-}0.1(11.4), 625.1{+-}0.2(6.1), 647.9{+-}0.2(10.7), 739.1{+-}0.3(8.7), 876.5{+-}0.3(6.7). K- and L-shell conversion coefficients have been measured for the 190. 3 keV transition, yielding a multipolarity of M1 + < 8 % E2. Half-life measurements using delayed coincidence technique have given the following results: T{sub 1/2} (190 keV level) = 1.27 {sup +0.06}{sub -0.10} ns, T{sub 1/2} (304 keV level) < 200 ps, T{sub 1/2} (467 keV level) < 120 ps. A level scheme of {sup 141}La has been constructed, and the spin-parity assignments of the ground state and first excited state are discussed in terms of the shell model.

  8. Electron irradiation of zeolites

    International Nuclear Information System (INIS)

    Wang, S.X.; Wang, L.M.; Ewing, R.C.

    1999-01-01

    Three different zeolites (analcime, natrolite, and zeolite-Y) were irradiated with 200 keV and 400 keV electrons. All zeolites amorphized under a relatively low electron fluence. The transformation from the crystalline-to-amorphous state was continuous and homogeneous. The electron fluences for amorphization of the three zeolites at room temperature were: 7.0 x 10 19 e - /cm 2 (analcime), 1.8 x 10 20 e - /cm 2 (natrolite), and 3.4 x 10 20 e - /cm 2 (zeolite-Y). The different susceptibilities to amorphization are attributed to the different channel sizes in the structures which are the pathways for the release of water molecules and Na + . Natrolite formed bubbles under electron irradiation, even before complete amorphization. Analcime formed bubbles after amorphization. Zeolite-Y did not form bubbles under irradiation. The differences in bubble formation are attributed to the different channel sizes of the three zeolites. The amorphization dose was also measured at different temperatures. An inverse temperature dependence of amorphization dose was observed for all three zeolites: electron dose for amorphization decreased with increasing temperature. This unique temperature effect is attributed to the fact that zeolites are thermally unstable. A semi-empirical model was derived to describe the temperature effect of amorphization in these zeolites

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

    International Nuclear Information System (INIS)

    Vuong Huu Tan; Nguyen Canh Hai; Pham Ngoc Son; Tran Tuan Anh

    2007-01-01

    In this fundamental research project on nuclear physics in period of 2006, the neutron capture cross sections for the reactions of 139 La (n,γ) 140 La, 152 Sm (n,γ) 153 Sm, 191 Ir (n,γ) 192 Ir and 193 Ir (n,γ) 194 Ir have been measured at 55 keV and 144 keV by the activation method using the filtered neutron beams of the Dalat nuclear research reactor. The cross sections were determined relative to the standard capture cross sections of 197 Au. The samples and standard were prepaid from high purity (99.99%) foil of Au and natural oxide powders of La 2 O 3 , Sm 2 O 3 and IrO 2 . A high efficient HPGe detector (58%) was used to detect the gamma rays, emitted from the activated samples. The absolute efficiency curve of the detector has been precisely calibrated thanks to a set of standard radioisotope sources and a multi-nuclide standard solution, supported by IAEA. The present results were compared with the previous measurements from EXFOR-2003, and the evaluated values of JENDL 3.3 and ENDF/B-6.8. (author)

  10. Electron energy measurements in pulsating auroras

    International Nuclear Information System (INIS)

    McEwan, D.J.; Yee, E.; Whalen, B.A.; Yau, A.W.

    1981-01-01

    Electron spectra were obtained during two rocket flights into pulsating aurora from Southend, Saskatchewan. The first rocket launched at 1143:24 UT on February 15, 1980 flew into an aurora of background intensity 275 R of N 2 + 4278 A and showing regular pulsations with about a 17 s period. Electron spectra of Maxwellian energy distributions were observed with an average E 0 = 1.5 keV, rising to 1.8 keV during the pulsations. There was one-to-one correspondence between the electron energy modulation and the observed optical pulsations. The second rocket, launched at 1009:10 UT on February 23, flew into a diffuse auroral surface of intensity 800 R of N 2 + 4278 A and with somewhat irregular pulsations. The electron spectra were again of Maxwellian energy distribution with an average E 0 = 1.8 keV increasing to 2.1 keV during the pulsations. The results from these flights suggest that pulsating auroras occurring in the morning sector may be quite commonly excited by low energy electrons. The optical pulsations are due to periodic increases in the energy of the electrons with the source of modulation in the vicintiy of the geomagnetic equatorial plane. (auth)

  11. Treatment of foods with 'soft-electrons' (low-energy electrons)

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Toru [Japan International Research Center for Agricultural Sciences (JIRCAS), Tsukuba, Ibaraki (Japan); Todoriki, Setsuko [National Food Research Institute (NFRI), Tsukuba, Ibaraki (Japan)

    2003-02-01

    Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

  12. Treatment of foods with 'soft-electrons' (low-energy electrons)

    International Nuclear Information System (INIS)

    Hayashi, Toru; Todoriki, Setsuko

    2003-01-01

    Electrons with energies of 300 keV or lower were defined as soft-electrons'. Soft-electrons can eradicate microorganisms residing on the surface of grains, pulses, spices, dehydrated vegetables, tea leaves and seeds, and reduce their microbial loads to levels lower than 10 CFU/g with little quality deterioration. Soft-electrons can inactivate insect pests infesting grains and pulses and inhibit sprouting of potatoes. (author)

  13. Response function and optimum configuration of semiconductor backscattered-electron detectors for scanning electron microscopes

    International Nuclear Information System (INIS)

    Rau, E. I.; Orlikovskiy, N. A.; Ivanova, E. S.

    2012-01-01

    A new highly efficient design for semiconductor detectors of intermediate-energy electrons (1–50 keV) for application in scanning electron microscopes is proposed. Calculations of the response function of advanced detectors and control experiments show that the efficiency of the developed devices increases on average twofold, which is a significant positive factor in the operation of modern electron microscopes in the mode of low currents and at low primary electron energies.

  14. Carotid dual-energy CT angiography: Evaluation of low keV calculated monoenergetic datasets by means of a frequency-split approach for noise reduction at low keV levels.

    Science.gov (United States)

    Riffel, Philipp; Haubenreisser, Holger; Meyer, Mathias; Sudarski, Sonja; Morelli, John N; Schmidt, Bernhard; Schoenberg, Stefan O; Henzler, Thomas

    2016-04-01

    Calculated monoenergetic ultra-low keV datasets did not lead to improved contrast-to-noise ratio (CNR) due to the dramatic increase in image noise. The aim of the present study was to evaluate the objective image quality of ultra-low keV monoenergetic images (MEIs) calculated from carotid DECT angiography data with a new monoenergetic imaging algorithm using a frequency-split technique. 20 patients (12 male; mean age 53±17 years) were retrospectively analyzed. MEIs from 40 to 120 keV were reconstructed using the monoenergetic split frequency approach (MFSA). Additionally MEIs were reconstructed for 40 and 50 keV using a conventional monoenergetic (CM) software application. Signal intensity, noise, signal-to-noise ratio (SNR) and CNR were assessed in the basilar, common, internal carotid arteries. Ultra-low keV MEIs at 40 keV and 50 keV demonstrated highest vessel attenuation, significantly greater than those of the polyenergetic images (PEI) (all p-values 0.05). Thus MEIs with MFSA showed significantly higher SNR and CNR compared to MEIs with CM. Combining the lower spatial frequency stack for contrast at low keV levels with the high spatial frequency stack for noise at high keV levels (frequency-split technique) leads to improved image quality of ultra-low keV monoenergetic DECT datasets when compared to previous monoenergetic reconstruction techniques without the frequency-split technique. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  15. Neutron Capture Gamma Ray Cross Sections for Ta, Ag, In and Au between 30 and 175 keV

    International Nuclear Information System (INIS)

    Hellstroem, J.; Beshai, S.

    1971-11-01

    A new detector has been used to determine neutron capture gamma ray cross sections for Ta, Ag, In and Au. The results are listed and discussed together with associated problems. The energy range from 30 keV to 175 keV is considered

  16. Neutron Capture Gamma Ray Cross Sections for Ta, Ag, In and Au between 30 and 175 keV

    Energy Technology Data Exchange (ETDEWEB)

    Hellstroem, J; Beshai, S

    1971-11-15

    A new detector has been used to determine neutron capture gamma ray cross sections for Ta, Ag, In and Au. The results are listed and discussed together with associated problems. The energy range from 30 keV to 175 keV is considered

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

    Science.gov (United States)

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

    2013-12-01

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

  18. Effects of low temperature periodic annealing on the deep-level defects in 200 keV proton irradiated AlGaAs-GaAs solar cells

    Science.gov (United States)

    Li, S. S.; Chiu, T. T.; Loo, R. Y.

    1981-01-01

    The GaAs solar cell has shown good potential for space applications. However, degradation in performance occurred when the cells were irradiated by high energy electrons and protons in the space environment. The considered investigation is concerned with the effect of periodic thermal annealing on the deep-level defects induced by the 200 keV protons in the AlGaAs-GaAs solar cells. Protons at a fluence of 10 to the 11th P/sq cm were used in the irradiation cycle, while annealing temperatures of 200 C (for 24 hours), 300 C (six hours), and 400 C (six hours) were employed. The most likely candidate for the E(c) -0.71 eV electron trap observed in the 200 keV proton irradiated samples may be due to GaAs antisite, while the observed E(v) +0.18 eV hole trap has been attributed to the gallium vacancy related defect. The obtained results show that periodic annealing in the considered case does not offer any advantages over the one time annealing process.

  19. First-principles dynamics treatment of light emission in collisions between alkali-metal atom and noble-gas atom collisions at 10keV

    Science.gov (United States)

    Pacheco, Alexander B.; Reyes, Andrés; Micha, David A.

    2006-12-01

    Collision-induced light emission during the interaction of an alkali-metal atom and a noble-gas atom is treated within a first-principles, or direct, dynamics approach that calculates a time-dependent electric dipole for the whole system, and spectral emission cross sections from its Fourier transform. These cross sections are very sensitive to excited diatomic potentials and a source of information on their shape. The coupling between electronic transitions and nuclear motions is treated with atomic pseudopotentials and an electronic density matrix coupled to trajectories for the nuclei. A recently implemented pseudopotential parametrization scheme is used here for the ground and excited states of the LiHe system, and to calculate state-to-state dipole moments. To verify the accuracy of our new parameters, we recalculate the integral cross sections for the LiHe system in the keV energy regime and obtain agreement with other results from theory and experiment. We further present results for the emission spectrum from 10keV Li(2s)+He collisions, and compare them to experimental values available in the region of light emitted at 300-900nm .

  20. Evolution of porous network in GaSb under normally incident 60 keV Ar{sup +}-ion irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Datta, D.P. [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India); Kanjilal, A. [Department of Physics, Shiv Nadar University, Gautam Budh Nagar 203 207, Uttar Pradesh (India); Garg, S.K. [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India); Sahoo, P.K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751 005, Odisha (India); Satpati, B. [Surface Physics and Material Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700 064 (India); Kanjilal, D. [Inter-University Accelerator Center, Aruna Asaf Ali Marg, New Delhi 110 067 (India); Som, T., E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751 005, Odisha (India)

    2014-08-15

    Highlights: • We show the evolution of a nanoporous layer in GaSb under Ar{sup +}-ion bombardment at normal incidence in the hitherto unexplored high fluence regime, namely 7 × 10{sup 16}–3 × 10{sup 18} ions cm{sup −2}. • Fluence dependent formation and growth of patches on top of the nanoporous layer is demonstrated by scanning electron microscopy. • We also show high amount of oxidation of such ion-beam-generated nanoporous structures, with formation of Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3}. • Our study reveals the presence of nanocrystallites within the porous layer even at the highest fluence used in the experiment. • We interpret the experimental observations through a qualitative model where we take into account the effect of re-deposition of atoms sputtered from the nanoporous layer during Ar{sup +}-ion irradiation of GaSb. - Abstract: GaSb(1 0 0) samples were irradiated with 60 keV Ar{sup +}-ions at normal incidence for fluences in the range of 7 × 10{sup 16} to 3 × 10{sup 18} ions cm{sup −2} at room temperature, showing gradual evolution of a porous surface layer containing interconnected nanofibers. In particular, fluence dependent formation of patches on the nanoporous layer is observed by scanning electron microscopy. Combined results of grazing incidence x-ray diffraction and transmission electron microscopy reveal the presence of nanocrystallites in the porous structures. Compositional analysis by x-ray photoelectron spectroscopy indicates the development of oxide phases, mainly Ga{sub 2}O{sub 3} and Sb{sub 2}O{sub 3} where the former increases with fluence. We have proposed a model addressing a competition between ion-induced-defect driven growth of the nanoporous layer and redeposition of sputtered target atoms on the growing layer.

  1. 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

    Energy Technology Data Exchange (ETDEWEB)

    Geloni, Gianluca [European XFEL GmbH, Hamburg (Germany); Kocharyan, Vitali; Saldin, Evgeni [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2012-07-15

    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. (orig.)

  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

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2012-07-01

    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 (π-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. (orig.)

  3. The Magnetic Local Time Distribution of Energetic Electrons in the Radiation Belt Region

    Science.gov (United States)

    Allison, H. J.

    2017-12-01

    Using fourteen years of electron flux data from the National Oceanic and Atmospheric Administration Polar Operational Environmental Satellites (POES), a statistical study of the magnetic local time (MLT) distribution of the electron population is performed across a range of activity levels, defined by AE, AE*, Kp, solar wind velocity (Vsw), and VswBz. Three electron energies (>30, >100, and >300 keV) are considered. Dawn-dusk flux asymmetries larger than order of magnitude were observed for >30 and >100 keV electrons. For >300 keV electrons, dawn-dusk asymmetries were primarily due to a decrease in the average dusk-side flux beyond L* ˜ 4.5 that arose with increasing activity. For the >30 keV population, substorm injections enhance the dawn-side flux, which may not reach the dusk-side as the electrons can be on open drift paths and lost to the magnetopause. The asymmetries in the >300 keV population are attributed to the combination of magnetopause shadowing and >300 keV electron injections by large electric fields. We suggest that 3D radiation belt models could set the minimum energy boundary (Emin) to 30 keV or above at L* ˜6 during periods of low activity. However, for more moderate conditions, Emin should be larger than 100 keV and, for very extreme activities, ˜300 keV. Our observations show the extent that in-situ electron flux readings may vary during active periods due to the MLT of the satellite and highlight the importance of 4D radiation belt models to fully understand radiation belt processes.

  4. 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)

  5. 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.

  6. Effect of 200 keV Ar+ implantation on optical and electrical properties of polyethyleneterepthalate (PET)

    International Nuclear Information System (INIS)

    Kumar, Rajiv; Goyal, Meetika; Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu; Kanjilal, D.

    2015-01-01

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

  7. Energy reflection coefficient for H+ ions at energies between 10 and 80 keV

    International Nuclear Information System (INIS)

    Chen, C.K.; Bohdansky, J.; Eckstein, W.; Robinson, M.T.

    1984-04-01

    The energy reflection coefficient for H + ions at energies between 10 keV and 80 keV was determined by experiments and by computer calculations. Measurements were made with graphite, Al, Cu, Mo and W. targets. The angle of ion incidence was restricted to 85 0 , 78 0 and 70 0 measured from the surface normal. Calculated data were obtained by two different Monte Carlo computer programs (MARLOWE, TRIM). It was found that both the calculated and the measured data scale with the parameter epsilon cos 2 α, where epsilon is Lindhard's reduced energy and α the angle of incidence for the ions. The measured values are smaller than those calculated. This can be explained by surface roughness which developed during the ion irradiation

  8. 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.

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

    International Nuclear Information System (INIS)

    Peurrung, Anthony; Arthur, Richard; Elovich, Robert; Geelhood, Bruce; Kouzes, Richard; Pratt, Sharon; Scheele, Randy; Sell, Richard

    2001-01-01

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

  10. Effect of 200 keV Ar+ implantation on optical & electrical properties of polyethyleneterepthalate (PET)

    Science.gov (United States)

    Kumar, Rajiv; Goyal, Meetika; Sharma, Ambika; Aggarwal, Sanjeev; Sharma, Annu; Kanjilal, D.

    2015-05-01

    In the present paper we have discussed the effect of 200 keV Ar+ ions on the electrical and optical properties of PET samples. PET samples were implanted with 200 keV Ar+ ions to various doses ranging from 1×1015 to 1×1017 Ar+ cm2. The changes in the electrical and optical properties of pristine and implanted PET specimens have been studied by using Keithley electrometer and UV-Visible absorption spectroscopy. The electrical conductivity has found to be increased with increasing ion dose. The optical studies have revealed the drastic alterations in optical band gap from 3.63 eV to 1.48 eV and also increase in number of carbon atoms per cluster from 215 to 537. Further, the change in the electrical conductivity and optical band gap has also been correlated with the formation of conductive islands in the implanted layers of PET.

  11. Evidence of a cyclotron line at 70 keV from 4U0531 + 21

    International Nuclear Information System (INIS)

    Polcaro, V.F.; Bazzano, A.; La Padula, C.D.; Ubertini, P.

    1981-01-01

    The HXR79 hard X-Ray experiment was flown August 26th 1979 from the Milo Base (Sicily, Italy) and a 27-hour flight was achieved. The scientific payload consisted of two Multiwire Spectroscopic Proportional Counters with 900 cm 2 sensitive geometric area each, in the hard X-Ray range (16 to 180 keV). A single drift scan was performed on the Crab Nebula region after the balloon reached the flotation point (2.9 mbar). The observation gave a maximum counting rate of about 25 counts/s superimposed on a background of about 75 counts/s. The Crab power-law spectrum was observed, and these data provide evidence for a line emission enhancement around 70 keV. (author)

  12. Biophysical interpretation of the response of Chinese hamster cells to 24 keV neutrons

    International Nuclear Information System (INIS)

    Holt, P.D.

    1988-01-01

    The response of V79 Chinese hamster cells to a 24 keV neutron spectrum has been compared with data for the response of V79 cells to a range of higher neutron energies (up to 15 MeV). The linear energy transfer (LET) distributions of the neutron spectra were calculated and the expected responses of the cells to the different spectra were calculated using published track-segment data on the response of V79 cells to charged particles with various LET values. The response of the cells to 24 keV neutrons was predicted satisfactorily by the LET distribution, in spite of the fact that the maximum range of the recoil protons is only 0.5 μm. The response was not correctly predicted by the microdosimetric parameter y-bar D * evaluated in a 1 μm diameter sphere. (author)

  13. A proton polarimeter for beam energies below 300 keV

    International Nuclear Information System (INIS)

    Buchmann, L.

    1990-10-01

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

  14. Picosecond x-ray measurements from 100 eV to 30 keV

    International Nuclear Information System (INIS)

    Attwood, D.T.; Kauffman, R.L.; Stradling, G.L.

    1980-01-01

    Picosecond x-ray measurements relevant to the Livermore Laser Fusion Program are reviewed. Resolved to 15 picoseconds, streak camera detection capabilities extend from 100 eV to higher than 30 keV, with synchronous capabilities in the visible, near infrared, and ultraviolet. Capabilities include automated data retrieval using charge coupled devices (CCD's), absolute x-ray intensity levels, novel cathodes, x-ray mirror/reflector combinations, and a variety of x-ray imaging devices

  15. Investigation of the 800 keV Peak in the Gamma Spectrum of Swedish Laplanders

    International Nuclear Information System (INIS)

    Andersson, I.Oe.; Nilsson, I.; Eckerstig, K.

    1962-08-01

    The gamma spectrum of the body radioactivity in reindeer raising Laplanders has shown a peak at 800 keV, which has not been discussed before in connection with whole body counting. We present here an investigation that was made to be able to identify the isotope. The result is that the peak comes from cesium 134. The possibility to find cesium 134 in fallout is discussed

  16. Investigation of the 800 keV Peak in the Gamma Spectrum of Swedish Laplanders

    Energy Technology Data Exchange (ETDEWEB)

    Andersson, I Oe; Nilsson, I; Eckerstig, K

    1962-08-15

    The gamma spectrum of the body radioactivity in reindeer raising Laplanders has shown a peak at 800 keV, which has not been discussed before in connection with whole body counting. We present here an investigation that was made to be able to identify the isotope. The result is that the peak comes from cesium 134. The possibility to find cesium 134 in fallout is discussed.

  17. Double and single ionization of helium by 58-keV X-rays

    International Nuclear Information System (INIS)

    Spielberger, L.; Buslaps, T.; Braeuning, H.; Gemmell, D.S.; Schmidt-Boecking, H.

    1996-03-01

    We have measured the ratio of cross sections for double to single ionization of helium by Compton scattering, R c =σ c ++ /σ c + at a photon energy of 58 keV using Cold Target Recoil Ion Momentum Spectroscopy. We find a value R c =(0.84 -11 +08 )% that is in agreement with the asymptotic limits predicted by Andersson and Burgdoerfer (Phys. Rev. A 50, R2810 (1994)) and Suric et al. (Phys. Rev. Lett. 73, 790 (1994)). (orig.)

  18. Study on the keV neutron capture reaction in 56Fe and 57Fe

    Science.gov (United States)

    Wang, Taofeng; Lee, Manwoo; Kim, Guinyun; Ro, Tae-Ik; Kang, Yeong-Rok; Igashira, Masayuki; Katabuchi, Tatsuya

    2014-03-01

    The neutron capture cross-sections and the radiative capture gamma-ray spectra from the broad resonances of 56Fe and 57Fe in the neutron energy range from 10 to 90keV and 550keV have been measured with an anti-Compton NaI(Tl) detector. Pulsed keV neutrons were produced from the 7Li 7Be reaction by bombarding the lithium target with the 1.5ns bunched proton beam from the 3MV Pelletron accelerator. The incident neutron spectrum on a capture sample was measured by means of a time-of-flight (TOF) method with a 6Li -glass detector. The number of weighted capture counts of the iron or gold sample was obtained by applying a pulse height weighting technique to the corresponding capture gamma-ray pulse height spectrum. The neutron capture gamma-ray spectra were obtained by unfolding the observed capture gamma-ray pulse height spectra. To achieve further understanding on the mechanism of neutron radiative capture reaction and study on physics models, theoretical calculations of the -ray spectra for 56Fe and 57Fe with the POD program have been performed by applying the Hauser-Feshbach statistical model. The dominant ingredients to perform the statistical calculation were the Optical Model Potential (OMP), the level densities described by the Mengoni-Nakajima approach, and the -ray transmission coefficients described by -ray strength functions. The comparison of the theoretical calculations, performed only for the 550keV point, show a good agreement with the present experimental results.

  19. Study of the Jet-Pini 160 keV optics in a single beamlet system

    International Nuclear Information System (INIS)

    Bottiglioni, F.; Bussac, J.P.; Jequier, F.

    1986-01-01

    The optics of the prototype of the extended performances PINI-injector, for the operation at 160 keV in D 2 , has been studied and tested on the separate test stand L.E.O., enabling experiments on a single beamlet. The results of the optics computations and of the experimentation on the beamlet are presented and discussed, namely as far profiles, divergence and steering are concerned

  20. Computer simulation of range and damage distributions of 0.5 to 8 keV helium ions in crystalline and amorphous niobium

    International Nuclear Information System (INIS)

    Maderlechner, G.

    1976-03-01

    The binary collision cascade simulation program MARLOWE is used to study the influence of the crystal lattice, electronic energy loss and crystal temperature on the range and damage distributions of 0.5 to 8 keV He ions penetrating into a Nb target. If the ions enter the crystal parallel to the close-packed direction, the penetration depth profiles show temperature dependent channeling and dechanneling effects. The range distributions in amorphous Nb agree generally with Lindhard's transport theory if surface effects are taken into account. The damage distributions are nearly independent of the electronic energy loss models. The number of vacancies per incident ion increases linearly with the mean nuclear energy loss of the ion in amorphous as well as in crystalline Nb. (orig./GSCH) [de

  1. Double excitation of helium in collisions with proton and antiproton impact in the energy range 50-500 keV

    International Nuclear Information System (INIS)

    Purkait, M.

    2009-01-01

    Double-electron excitation processes of helium atoms by proton and antiproton impact have been theoretically investigated using the four-body formalism of boundary corrected continuum intermediate state (BCCIS-4B) approximation in the energy range of 50-500 keV. In this formalism, the presence of the projectile in the exit channels is described by distorting the final bound state wave functions with coulomb waves (associated with the projectile-electron interactions). The results are in good agreement with the other theoretical and experimental results. Reasonably better agreements have been found in the intermediate and high energy regions. Contributions to the cross section of the different magnetic sub-shells are also analysed.

  2. A 3.55 keV line from DM →a→γ: predictions for cool-core and non-cool-core clusters

    Energy Technology Data Exchange (ETDEWEB)

    Conlon, Joseph P.; Powell, Andrew J. [Rudolf Peierls Centre for Theoretical Physics, University of Oxford, 1 Keble Road, Oxford, OX1 3NP (United Kingdom)

    2015-01-13

    We further study a scenario in which a 3.55 keV X-ray line arises from decay of dark matter to an axion-like particle (ALP), that subsequently converts to a photon in astrophysical magnetic fields. We perform numerical simulations of Gaussian random magnetic fields with radial scaling of the magnetic field magnitude with the electron density, for both cool-core 'Perseus' and non-cool-core 'Coma' electron density profiles. Using these, we quantitatively study the resulting signal strength and morphology for cool-core and non-cool-core clusters. Our study includes the effects of fields of view that cover only the central part of the cluster, the effects of offset pointings on the radial decline of signal strength and the effects of dividing clusters into annuli. We find good agreement with current data and make predictions for future analyses and observations.

  3. Total L-shell X-ray production cross sections by 400-700 keV proton impact for elements with 34≤Z≤53

    International Nuclear Information System (INIS)

    Miranda, J.; Ledesma, R.; Lucio, O.G. de

    2001-01-01

    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 ξ L 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

  4. The ASDEX 100 keV neutral lithium beam diagnostic gun

    International Nuclear Information System (INIS)

    McCormick, K.; Kick, M.

    1983-04-01

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

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

    International Nuclear Information System (INIS)

    Lonjou, V.

    2005-09-01

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

  6. The appearance and disappearance of the 17-keV neutrino

    International Nuclear Information System (INIS)

    Franklin, A.

    1995-01-01

    It is a fact of life in empirical science that experiments often give discordant results. This is nowhere better illustrated than in the recent history of experiments concerning the existence of a heavy, 17-keV neutrino. The 17-keV neutrino was first ''discovered'' by Simpson in 1985. The initial replications of the experiment all gave negative results, and suggestions were made that attempted to explain Simpson's result using accepted physics, without the need for a heavy neutrino. Subsequent positive results by Simpson and others led to further investigation. Several of these later experiments found evidence supporting that claim, whereas others found no evidence for such a particle. Some theorists attempted to explain away the result, and others tried to explain it and to incorporate it within existing theory without the need for a new particle, or to look for the further implications of such a particle, or to propose a new theory that would incorporate the new particle. The question of the existence of such a heavy neutrino remained for several years. Recently, doubt has been cast on the two most convincing positive experimental results, and errors have been found in those experiments. In addition, recent, extremely sensitive experiments have found no evidence for the 17-keV neutrino. The consensus is that it does not exist. The discord has been resolved by a combination of finding errors in one set of experiments and a preponderance of evidence

  7. The energy spectrum of 662 keV photons in a water equivalent phantom

    International Nuclear Information System (INIS)

    Akar Tarim, U.; Gurler, O.; Ozmutlu, E.N.; Yalcin, S.; Gundogdu, O.; Sharaf, J.M.; Bradley, D.A.

    2012-01-01

    Investigation is made on the energy spectrum of photons originating from interactions of 662 keV primary gamma-ray photons emitted by a point source positioned at the centre of a water equivalent solid phantom of dimensions 19 cm×19 cm×24 cm. Peaks resulting from total energy loss (photopeak) and multiple and back scattering have been observed using a 51 mm×51 mm NaI(Tl) detector; good agreement being found between the measured and simulated response functions. The energy spectrum of the gamma photons obtained through the Monte Carlo simulation reveals local maxima at about 100 keV and 210 keV, being also observed in the experimental response function. Such spectra can be used as a method of testing the water equivalence of solid phantom media before their use for dosimetry measurements. - Highlights: ► Peaks resulting from total energy loss (photopeak) and multiple and back scattering were observed. ► Energy distribution of γ-ray photons from a point source at the centre of a water equivalent solid phantom. ► The method can be applied to various detector geometries.

  8. Construction, calibration and test of an ionization chamber for exposure measurement of x and gamma radiation in region from 40 keV to 1250 keV

    International Nuclear Information System (INIS)

    Campos, C.A.A.L.

    1982-01-01

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

  9. Feasibility study for mega-electron-volt electron beam tomography.

    Science.gov (United States)

    Hampel, U; Bärtling, Y; Hoppe, D; Kuksanov, N; Fadeev, S; Salimov, R

    2012-09-01

    Electron beam tomography is a promising imaging modality for the study of fast technical processes. But for many technical objects of interest x rays of several hundreds of keV energy are required to achieve sufficient material penetration. In this article we report on a feasibility study for fast electron beam computed tomography with a 1 MeV electron beam. The experimental setup comprises an electrostatic accelerator with beam optics, transmission target, and a single x-ray detector. We employed an inverse fan-beam tomography approach with radiographic projections being generated from the linearly moving x-ray source. Angular projections were obtained by rotating the object.

  10. Synthesis of sponge-like hydrophobic NiBi_3 surface by 200 keV Ar ion implantation

    International Nuclear Information System (INIS)

    Siva, Vantari; Datta, D.P.; Chatterjee, S.; Varma, S.; Kanjilal, D.; Sahoo, Pratap K.

    2017-01-01

    Highlights: • A sponge-like hydrophobic NiBi_3 surface has been synthesized using 200 keV Ar ion implantation. • A competition between amorphization and re-crystallization was observed in the existing phases owing to comparable magnitudes of nuclear and electronic energy depositions. • The relation between hydrophobic nature and sponge-like NiBi_3 phase seems interesting, which is attributed to ion beam induced sputtering and mixing of the layers. - Abstract: Sponge-like nanostructures develop under Ar-ion implantation of a Ni–Bi bilayer with increasing ion fluence at room temperature. The surface morphology features different stages of evolution as a function of ion fluence, finally resulting in a planar surface at the highest fluence. Our investigations on the chemical composition reveal a spontaneous formation of NiBi_3 phase on the surface of the as deposited bilayer film. Interestingly, we observe a competition between crystallization and amorphization of the existing poly-crystalline phases as a function of the implanted fluence. Measurements of contact angle by sessile drop method clearly show the ion-fluence dependent hydrophobic nature of the nano-structured surfaces. The wettability has been correlated with the variation in roughness and composition of the implanted surface. In fact, our experimental results confirm dominant effect of ion-sputtering as well as ion-induced mixing at the bilayer interface in the evolution of the sponge-like surface.

  11. Study of surface activation of PET by low energy (keV) Ni+ and N+ ion implantation

    International Nuclear Information System (INIS)

    Nathawat, Rashi; Kumar, Anil; Kulshrestha, V.; Vijay, Y.K.; Kobayashi, T.; Kanjilal, D.

    2008-01-01

    Polyethyleneterephthalate (PET) has been modified by 100 keV Ni + and N + ions using metal ion from volatile compound (MIVOC) ion source to fluence ranging from 1 x 10 14 to 1 x 10 16 ions/cm 2 . The increasing application of polymeric material in technological and scientific field has motivated the use of surface treatment to modify the physical and chemical properties of polymer surfaces. When a material is exposed to ionization radiation, it suffers damage leading to surface activation depending on the type. The surface morphology was observed by atomic force microscopy (AFM). That show the roughness increases with fluence in both the cases. The Ni particles as precipitation in PET were observed by cross-section transmission electron microscopy (XTEM). The optical band gap (E g ) deduced from absorption spectra; was calculated by Tau'c relation. Raman spectroscopy shows quantitatively the chemical nature at the damage caused by the Ni + and N + bombardment. The ration of I D /I G shows graphite-like structure is formed on the surface. A layer of hydrogenated amorphous carbon is formed on the surface, which has confirmed by XPS results also.

  12. 1974 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. It is being admired by Helmut Haseroth and Jean Luc Vallet (during servicing). 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 supply (not included in this photo) was originally a Cockcroft-Walton generator. In 1973 it was replaced by a Sames generator (see 7403074X). 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). It had a 750 keV "Cockcroft-Walton" (see 760...

  13. FLUKA and PENELOPE simulations of 10keV to 10MeV photons in LYSO and soft tissue

    CERN Document Server

    Chin, M P W; Fassò, A; Ferrari, A; Ortega, P G; Sala, P R

    2014-01-01

    Monte Carlo simulations of electromagnetic particle interactions and transport by FLUKA and PENELOPE were compared. 10 key 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 overestimate 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 key sharp line, whereas FLUKA produced visible acolinearity, a feature recently implemen...

  14. 60 keV Ar⁺-ion induced modification of microstructural, compositional, and vibrational properties of InSb

    Energy Technology Data Exchange (ETDEWEB)

    Datta, D. P.; Garg, S. K.; Som, T., E-mail: tsom@iopb.res.in [SUNAG Laboratory, Institute of Physics, Bhubaneswar, Odisha 751005 (India); Satpati, B. [Surface Physics and Materials Science Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Sahoo, P. K. [School of Physical Sciences, National Institute of Science Education and Research, Bhubaneswar 751005, Odisha (India); Kanjilal, A. [Department of Physics, Shiv Nadar University, Uttar Pradesh 203207 (India); Dhara, S. [Surface and Nanoscience Division, Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam 603102 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India)

    2014-10-14

    Room temperature irradiation of InSb(111) by 60 keV Ar⁺-ions at normal (0°) and oblique (60°) angles of incidence led to the formation of nanoporous structure in the high fluence regime of 1×10¹⁷ to 3×10¹⁸ ions cm⁻². While a porous layer comprising of a network of interconnected nanofibers was generated by normal ion incidence, evolution of plate-like structures was observed for obliquely incident ions. Systematic studies of composition and structure using energy dispersive x-ray spectroscopy, Raman spectroscopy, x-ray photoelectron spectroscopy, Raman mapping, grazing incidence x-ray diffraction, and cross-sectional transmission electron microscopy revealed a high degree of oxidation of the ion-induced microstructures with the presence of In₂O₃ and Sb₂O₃ phases and presence of nanocrystallites within the nanoporous structures. The observed structural evolution was understood in terms of processes driven by ion-induced defect accumulation within InSb.

  15. Synthesis of sponge-like hydrophobic NiBi{sub 3} surface by 200 keV Ar ion implantation

    Energy Technology Data Exchange (ETDEWEB)

    Siva, Vantari; Datta, D.P. [School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni 752050 (India); Chatterjee, S. [Colloids and Materials Chemistry Department, CSIR-Institute of Minerals and Materials Technology, Acharya Vihar, Bhubaneswar 751 013 (India); Varma, S. [Institute of Physics, Sachivalaya Marg, Bhubaneswar 751005 (India); Kanjilal, D. [Inter-University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Sahoo, Pratap K., E-mail: pratap.sahoo@niser.ac.in [School of Physical Sciences, National Institute of Science Education and Research, HBNI, Jatni 752050 (India)

    2017-07-15

    Highlights: • A sponge-like hydrophobic NiBi{sub 3} surface has been synthesized using 200 keV Ar ion implantation. • A competition between amorphization and re-crystallization was observed in the existing phases owing to comparable magnitudes of nuclear and electronic energy depositions. • The relation between hydrophobic nature and sponge-like NiBi{sub 3} phase seems interesting, which is attributed to ion beam induced sputtering and mixing of the layers. - Abstract: Sponge-like nanostructures develop under Ar-ion implantation of a Ni–Bi bilayer with increasing ion fluence at room temperature. The surface morphology features different stages of evolution as a function of ion fluence, finally resulting in a planar surface at the highest fluence. Our investigations on the chemical composition reveal a spontaneous formation of NiBi{sub 3} phase on the surface of the as deposited bilayer film. Interestingly, we observe a competition between crystallization and amorphization of the existing poly-crystalline phases as a function of the implanted fluence. Measurements of contact angle by sessile drop method clearly show the ion-fluence dependent hydrophobic nature of the nano-structured surfaces. The wettability has been correlated with the variation in roughness and composition of the implanted surface. In fact, our experimental results confirm dominant effect of ion-sputtering as well as ion-induced mixing at the bilayer interface in the evolution of the sponge-like surface.

  16. Maskless nano-implant of 20 keV Ga{sup +} in bulk Si(1 0 0) substrates

    Energy Technology Data Exchange (ETDEWEB)

    Milazzo, R.G., E-mail: gabriella.milazzo@gmail.com [IMM-CNR, Strada VIII 5, Zona Industriale, I-95121 Catania (Italy); D’Arrigo, G.; Mio, A.M.; Rimini, E.; Spinella, C. [IMM-CNR, Strada VIII 5, Zona Industriale, I-95121 Catania (Italy); Peto, L.; Nadzeyka, A.; Bauerdick, S. [Raith GmbH, Konrad-Adenauer-Allee 8, 44263 Dortmund (Germany)

    2014-12-15

    Multidirectional SPEG (Solid Phase Epitaxial Growth) of silicon has been investigated in micro and nanoamorphous structures generated on a crystalline substrate by a nano-sized ion beam, Gaussian shaped and with a standard deviation of about 5 nm. The 20 keV Ga{sup +} ions were implanted at a fluence of 5 × 10{sup 14} ions cm{sup −2} in a bulk Si(1 0 0) single crystal. Two structures were used for the implants: circular regions of 100 nm and 1 μm diameters respectively and straight lines 10 nm in width and few microns in length along (1 0 0) or (1 1 0) directions. The lateral spread of ions has been taken into account in the damage estimation. Transmission Electron Microscopy indicates that the structures are made of an amorphous core surrounded by a defective and filamentary shell. The recovery of the damaged outer regions promptly occurs during the early stages of the thermal treatment at 500–600 °C for all the structures. By prolonging annealing time, re-crystallization of the amorphous cores is achieved too by the movement of the underneath crystal–amorphous interface. The re-growth is almost defects free when the contribution of the crystalline seed below the structures is present, defective and twin mediated if it misses as in the thinnest regions of the specimen.

  17. Compton polarimetry of 6-35 keV X-rays. Influence of Breit interaction on the linear polarisation of KLL dielectronic recombination transitions in highly charged ions

    Energy Technology Data Exchange (ETDEWEB)

    Joerg, Holger Eric

    2016-12-21

    The polarisation of X-rays emitted during K shell dielectronic recombination (DR) into highly charged ions was studied using electron beam ion traps. In the first experiment, the degree of linear polarisation of X-rays due to K shell DR transitions of highly charged krypton ions was measured with a newly developed Compton polarimeter based on SiPIN diodes. Such polarisation measurements allow a study of the population mechanism of magnetic sublevels in collisions between electrons and ions. In a second experiment, the influence of Breit interaction between electrons on the polarisation of X-rays emitted during K shell DR into highly charged xenon ions was studied. Here, polarisation measurements provide an access to the finer details of the electron-electron interaction in electron-ion collisions. Furthermore, a second Compton polarimeter based on silicon drift detectors has been developed for polarisation measurements at synchrotrons. It has been developed for X-ray polarimetry with a high energy resolution for energies between 6 keV and 35 keV. It was tested in the course of polarisation measurements at an electron beam ion trap and at a synchrotron radiation source.

  18. Multi-stage autoacceleration of an intense relativistic electron beam

    Energy Technology Data Exchange (ETDEWEB)

    Kamada, K; Hasegawa, D; Igarashi, H; Kusunoki, T; Lee, C Y; Koguchi, H; Ando, R; Masuzaki, M [Kanazawa Univ. (Japan). Department of Physics

    1997-12-31

    Two-stage autoacceleration was accomplished by using different length cavities. Two cavities were located with the distance longer than the beam duration. The electron kinetic energy increased from 500 to 700 keV at the first stage and from 700 to 900 keV at the second, while the beam duration decreased 10 to 5 ns at the first stage and 5 to 2.5 ns at the second. (author). 7 figs., 7 refs.

  19. Double electron capture by protons in collisions with H2

    International Nuclear Information System (INIS)

    Salazar-Zepeda, M.H.; Gleason, Cristian; Gonzalez, Eduardo; Gonzalez-Magana, O.; Hinojosa, Guillermo

    2010-01-01

    Double electron capture of protons in collisions with molecular hydrogen in the energy range 1.5-10 keV was studied by measuring the resulting H - velocity distributions. In this paper, a technique that provides experimental evidence about double capture mechanisms is proposed. In addition, cross-sections for this process were measured in the energy range of 1-5 keV.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-01

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

  1. Calibration of a dePangher long counter from 2 keV to 19 MeV

    Energy Technology Data Exchange (ETDEWEB)

    Slaughter, D R; Rueppel, D W [California Univ., Livermore (USA). Lawrence Livermore Lab.

    1977-09-01

    The authors have measured the sensitivity of a dePangher precision long counter (PLC) relative to /sup 7/Li(p,n), T(p,n), and T(d,n) differential cross sections over the neutron energy range 10 keV-19 MeV. Absolute sensitivity at 2 keV is also measured, using a scandium filtered beam at a reactor. Results obtained with errors in the range 5-30% are consistent with the assumption of a nearly constant sensitivity over the range 2 keV-6 MeV, but exhibit a reduction above 12 MeV.

  2. Electron Flux Models for Different Energies at Geostationary Orbit

    Science.gov (United States)

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

    2016-01-01

    Forecast models were derived for energetic electrons at all energy ranges sampled by the third-generation Geostationary Operational Environmental Satellites (GOES). These models were based on Multi-Input Single-Output Nonlinear Autoregressive Moving Average with Exogenous inputs methodologies. The model inputs include the solar wind velocity, density and pressure, the fraction of time that the interplanetary magnetic field (IMF) was southward, the IMF contribution of a solar wind-magnetosphere coupling function proposed by Boynton et al. (2011b), and the Dst index. As such, this study has deduced five new 1 h resolution models for the low-energy electrons measured by GOES (30-50 keV, 50-100 keV, 100-200 keV, 200-350 keV, and 350-600 keV) and extended the existing >800 keV and >2 MeV Geostationary Earth Orbit electron fluxes models to forecast at a 1 h resolution. All of these models were shown to provide accurate forecasts, with prediction efficiencies ranging between 66.9% and 82.3%.

  3. The SPEDE electron spectrometer

    CERN Document Server

    O'Neill, George

    This thesis presents SPEDE (SPectrometer for Electron DEtection) and documents its construction, testing and performance during commissioning at Jyvaskyla, Finland, before deployment at the HIE-ISOLDE facility at CERN coupled with the MINIBALL array to perform in-beam electron-gamma spectroscopy using post-accelerated radioactive ion beams. Commissioning experiments took place in two two-day stints during spring 2015, coupled with several JUROGAMII gamma-detectors. This spectrometer will help aid in fully understanding exotic regions of the nuclear chart such as regions with a high degree of octupole deformation, and in those nuclei exhibiting shape coexistence. For the rst time, electron spectroscopy has been performed at the target position from states populated in accelerated nuclei via Coulomb excitation. The FWHM of SPEDE is approximately 7 keV at 320 keV, and Doppler correction was possible to improve Doppler broadened peaks. The results are intended to give the reader a full understanding of the dete...

  4. Analysis of electron cyclotron emission spectra of high electron temperature, supershot plasmas in TFTR

    International Nuclear Information System (INIS)

    Taylor, G.; Arunasalam, V.; Efthimion, P.C.; Grek, B.

    1993-01-01

    A primary objective of the TFTR program since 1986 has been the study and optimization of deuterium Supershot plasmas. These plasmas are predominantly heated by 90-110 keV neutral deuterium beams (P NBI /P OH >30), central ion temperatures are ∝30 keV and central electron temperatures from ECE (T ECE ) often exceed 10 keV. Central electron temperature data measured with a TV Thomson scattering (TVTS) system (T TVTS ) during the period 1987-1990 have been compared with data from three different ECE instruments on TFTR. Although T ECE ∝T TVTS for temperatures below 6 keV, there is a systematically increasing disagreement at higher electron temperatures, with T ECE ∝1.2 T TVTS for T TVTS in the range 9-10 keV. Recent theoretical work on the ECE radiation temperature of non-equilibrium plasmas indicates that for a bi-Maxwellian electron velocity distribution with a ratio of tail to bulk electron density η, a bulk temperature T b , and a hot tail temperature T h , the perpendicular ECE radiation temperature is given by T ECE ∝T b {1+η(T h /T b )}, for η ECE would be enhanced over T TVTS by a factor which depends on η and T h . This paper investigates whether the discrepancy between T TVTS and T ECE seen in TFTR Supershots at high electron temperatures is due to the presence of a hot electron tail component. The extraordinary mode ECE spectrum at the second, third and fourth harmonics is measured on the horizontal midplane by an absolutely calibrated ECE Michelson interferometer. This ECE spectrum is compared with the output from a time-independent transport code with relativistic opacity which solves the three-dimensional ECE radiation transport in a toroidally symmetric, two-dimensional geometry and uses measured electron density and temperature profiles from the TVTS system. (orig.)

  5. A 'tiny-orange' spectrometer for electrons

    International Nuclear Information System (INIS)

    Silva, N.C. da.

    1990-01-01

    An tiny-orange electron spectrometer was designed and constructed using flat permanent magnets and a surface barrier detector. The transmission functions of different system configurations were determined for energies in the 200-1100 KeV range. A mathematical model for the system was developed. (L.C.J.A.)

  6. New experimental results on electron cooling at COSY-Juelich

    International Nuclear Information System (INIS)

    Dietrich, J.; Maier, R.; Prasuhn, D.; Stein, H.J.; Kobets, A.; Meshkov, I.; Sidorin, A.; Smirnov, A.

    2007-01-01

    Recent results of electron cooling of proton beams at COSY-Juelich are reported. Cooling at an electron energy of 70 keV has been studied for the first time. At the injection energy level of COSY, corresponding to 24.5 keV electron energy, the features of the cooled proton beam at extremely low intensities have been investigated in order to find out whether an ordering of the proton beam can be achieved. Such investigations are motivated by the results of a numerical simulation of the ordering process by the BETACOOL code. (author)

  7. Development of a high current 60 keV neutral lithium beam injector for beam emission spectroscopy measurements on fusion experiments

    Science.gov (United States)

    Anda, G.; Dunai, D.; Lampert, M.; Krizsanóczi, T.; Németh, J.; Bató, S.; Nam, Y. U.; Hu, G. H.; Zoletnik, S.

    2018-01-01

    A 60 keV neutral lithium beam system was designed and built up for beam emission spectroscopy measurement of edge plasma on the KSTAR and EAST tokamaks. The electron density profile and its fluctuation can be measured using the accelerated lithium beam-based emission spectroscopy system. A thermionic ion source was developed with a SiC heater to emit around 4-5 mA ion current from a 14 mm diameter surface. The ion optic is following the 2 step design used on other devices with small modifications to reach about 2-3 cm beam diameter in the plasma at about 4 m from the ion source. A newly developed recirculating sodium vapour neutralizer neutralizes the accelerated ion beam at around 260-280 °C even during long (manipulation techniques are applied to allow optimization, aiming, cleaning, and beam modulation. The maximum 60 keV beam energy with 4 mA ion current was successfully reached at KSTAR and at EAST. Combined with an efficient observation system, the Li-beam diagnostic enables the measurement of the density profile and fluctuations on the plasma turbulence time scale.

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

    Science.gov (United States)

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

    2012-12-21

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-07-25

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

  10. Contribution to the measurement of the reflection coefficient for curved crystals between 50 and 80 keV; Contribution a la mesure du coefficient de reflexion de cristaux courbes entre 50 keV et 80 keV

    Energy Technology Data Exchange (ETDEWEB)

    Chartier, J [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-09-01

    In the first part, we summarize the main approximate theories dealing with the diffraction of electromagnetic radiation by the crystalline medium, allowing the determination of the characteristic properties of flat and bent crystals used in X and gamma-Ray spectroscopy ('Laue Case'). We describe the experimental setting and we explain our method to measure {gamma}: reflectivity of elastically or plastically bent-crystals from narrow wave-length intervals in the continuous X-Ray spectrum. We discuss our experimental results obtained with different crystals (quartz (3140), Al (200), FLi (200) and compare them with theoretical ones. Finally, we refer to a use of the bent-crystal spectrometer (Cauchois arrangement) in dosimetry. (author) [French] Dans la premiere partie, nous resumons les principales approximations theoriques qui traitent la diffraction du rayonnement electromagnetique par le milieu cristallin et permettent de determiner les grandeurs caracteristiques des lames cristallines planes ou courbees utilisees 'par transmission' en spectroscopie X ou gamma. Apres avoir decrit le montage experimental, nous exposons la methode de mesure de {gamma}: coefficient de reflexion de cristaux courbes (elastiquement ou plastiquement). Le domaine energetique etudie est voisin de 100 keV. Dans cette methode, nous n'utilisons pas des rayonnements monoenergetiques provenant de transitions atomiques ou nucleaires mais des bandes etroites d'energie appartenant au spectre continu du rayonnement emis par un tube a rayons X. Les resultats experimentaux obtenus avec differents cristaux (quartz (3140), Al (200), FLi (200)) sont discutes et compares a ceux prevus par la theorie. Nous mentionnons, enfin, une application en dosimetrie du spectrographe a cristal couche (Geometrie Cauchois). (auteur)

  11. NEW OBSERVATIONS OF THE SOLAR 0.5–5 KEV SOFT X-RAY SPECTRUM

    Energy Technology Data Exchange (ETDEWEB)

    Caspi, Amir; Woods, Thomas N. [Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303 (United States); Warren, Harry P. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)

    2015-03-20

    The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the high-temperature corona, and is also an important driver of ionospheric dynamics at Earth. There is a crucial observational gap between ∼0.2 and ∼4 keV, outside the ranges of existing spectrometers. We present observations from a new SXR spectrometer, the Amptek X123-SDD, which measured the spatially integrated solar spectral irradiance from ∼0.5 to ∼5 keV, with ∼0.15 keV FWHM resolution, during sounding rocket flights on 2012 June 23 and 2013 October 21. These measurements show that the highly variable SXR emission is orders of magnitude greater than that during the deep minimum of 2009, even with only weak activity. The observed spectra show significant high-temperature (5–10 MK) emission and are well fit by simple power-law temperature distributions with indices of ∼6, close to the predictions of nanoflare models of coronal heating. Observations during the more active 2013 flight indicate an enrichment of low first-ionization potential elements of only ∼1.6, below the usually observed value of ∼4, suggesting that abundance variations may be related to coronal heating processes. The XUV Photometer System Level 4 data product, a spectral irradiance model derived from integrated broadband measurements, significantly overestimates the spectra from both flights, suggesting a need for revision of its non-flare reference spectra, with important implications for studies of Earth ionospheric dynamics driven by solar SXRs.

  12. Properties of the transitions populating and depopulating the 279 keV level in /sup 75/As

    Energy Technology Data Exchange (ETDEWEB)

    Puri, V S; Khurana, C S; Sahota, H S [Punjabi Univ., Patiala (India). Nuclear Science Labs.

    1977-09-01

    The low-energy gamma-ray spectrum of /sup 75/As from /sup 75/Sc has been investigated using a 6 mm x 6 mm Si(Li) spectrometer. The intensity of the 24.4 keV transition has been found to be 0.07 +- 0.01. No evidence has been found for the presence of a 14.9 keV transition. From directional correlation measurements involving the 24.4 keV transition detected in the Si(Li) detector, the multipolarity of this transition has been found to be delta(E3/M2)sub(24.4) =0.18 +- 0.02. The internal conversion process of the 279 keV transition seems to be normal. No effect of the chemical environment has been observed on the (121 ..gamma..-279..gamma..) directional correlation coefficients.

  13. Effect of 200 keV proton irradiation on the properties of methyl silicone rubber

    International Nuclear Information System (INIS)

    Zhang Lixin; Xu Zhou; Wei Qiang; He Shiyu

    2006-01-01

    The effects of 200 keV proton irradiation on methyl silicone rubber were studied. The changes in surface morphology, mechanical properties, cross-linking density, glass transition temperature, infrared attenuated total reflection spectrum and mass spectrum indicated that, at lower fluence, the proton irradiation induced cross-linking, resulting in an increase in tensile strength and hardness of the methyl silicone rubber. However, at higher proton fluence, radiation-induced degradation, which decreased the tensile strength and hardness, became dominant. A macromolecular-network destruction model for silicone rubber irradiated with protons was proposed

  14. Numerical simulation of range and backscattering for keV protons incident on random targets

    International Nuclear Information System (INIS)

    Robinson, J.E.; Agamy, S.

    1975-01-01

    Using a Monte-Carlo technique, projected range distributions and backscattering coefficients have been calculated for keV protons normally incident on heavy targets. For an incident reduced energy range of 1 less than epsilon 0 less than 20, both the projected range distributions and backscattering coefficients have been found to be in good agreement with a third order Edgeworth range approximation. Backscattered energy and angular distributions have also been calculated and are compared to available theoretical and experimental data. (4 figs.) (U.S.)

  15. Biological effect of 20 keV N+ ion implantation on Stevia rebaudianum

    International Nuclear Information System (INIS)

    Su Tingting; Yang Tingting; Ji Guohong; Xiang Xingjia; Chen Xuetao; Wang Yu; Wu Yaojin

    2010-01-01

    The germinability and gemination rate of Stevia rebaudianum seeds implanted with 20 keV N + ions in doses of 0 (CK), 100 x 2500, 400 x 2500 and 1000 x 2500 N + /cm 2 were studied by analyzing the differences in seed germinability and gemination rate between the groups. By statistical analysis, the germinability and gemination rate were affected at the level of α=0.05 by the implantation dose. The results showed that the germinability and gemination rate increased with the dose first and then decreased. At 400 x 2500 N + /cm 2 , the seeds had the largest germinability and the gemination rate. (authors)

  16. Development of scanning magnet for 750 keV DC accelerator

    International Nuclear Information System (INIS)

    Pramod, R.; Pankaj Kumar; Venkateswaran, S.V.; Bapna, S.C.

    2003-01-01

    In the radiation processing technologies, the surface to be irradiated has to be as large as possible, but keeping a good uniformity of the absorbed dose. To attain such a goal, the beam should be scanned in a plane perpendicular on the displacement of the conveyor belt. Therefore, scanning magnets are necessary. A scanning magnet should ensure the homogeneity of the absorbed dose (and, similarly, of the beam current distribution) on the items to be irradiated. In this paper some simple relations needed in the design of the scanning magnets are deduced, the design and fabrication aspects of the scanning magnet for the 750 keV DC accelerator are discussed

  17. Measurements on a Gabor lens for neutralizing and focusing a 30 keV proton beam

    International Nuclear Information System (INIS)

    Palkovic, J.A.; Hren, R.; Lee, G.; Mills, F.E.; Schmidt, C.W.; Wendt, J.; Young, D.E.

    1989-01-01

    The authors have reported previously on the use of a Gabor lens (also referred to as a plasma or space charge lens) to focus and neutralize a low energy proton beam. A different lens geometry and a higher anode voltage have been adopted to overcome a lack of stability present in the previous design. They report on studies in progress to measure the focusing properties of the Gabor lens and determine whether it can be used to match a 30 keV proton beam into radio frequency quadrupole (RFQ) Accelerator. 10 refs., 4 figs

  18. 2 keV filters of quasi-mono-energetic neutrons

    International Nuclear Information System (INIS)

    Adib, M.; Habib, N.; El-Mesiry, M.S.; Bashter, I.I.; Saleh, A.; Fathallah, M.

    2013-01-01

    A simulation study for the production of 2 keV filters of quasi-mono-energetic neutrons based on the deep interference minima in the 45 Sc total cross-section was carried out. A computer code QMENF-II was adapted to calculate the optimum amounts of the 45 Sc as a main filter element and additional component ones to obtain sufficient intensity at high resolution and purity of the filtered quasi-mono-energetic neutrons. The emitted neutron spectrum from nuclear reactor and from the reaction of 2.6 MeV protons on a lithium fluoride target at the accelerator beam port, are used for simulation

  19. Electrical conduction in 100 keV Kr+ ion implanted poly (ethylene terephthalate)

    Science.gov (United States)

    Goyal, P. K.; Kumar, V.; Gupta, Renu; Mahendia, S.; Anita, Kumar, S.

    2012-06-01

    Polyethylene terephthalate (PET) samples have been implanted to 100 keV Kr+ ions at the fluences 1×1015-- 1×1016 cm-2. From I-V characteristics, the conduction mechanism was found to be shifted from ohmic to space charge limited conduction (SCLC) after implantation. The surface conductivity of these implanted samples was found to increase with increasing implantation dose. The structural alterations in the Raman spectra of implanted PET samples indicate that such an increase in the conductivity may be attributed to the formation of conjugated double bonded carbonaceous structure in the implanted layer of PET.

  20. Search of a cyclotron line at 70 keV from Crab Nebula

    International Nuclear Information System (INIS)

    Ubertini, P.; Bazzano, A.; La Padula, C.D.; Polcaro, V.F.

    1980-01-01

    An observation of Crab Nebula was made during a transmediterranean balloon flight launched on August 26, 1979 from Milo Base (Sicily, Italy). The hard X-ray experiment (HXR 79) carried a payload consisting of two multiwire proportional counters having a geometric area of 900 cm 2 each. A single transit scan of the source was performed on the Crab Nebula region at a float altitude of 2.9 mbs. The preliminary results indicate the existence of an excess flux between 64 - 76 KeV above the expected value of Esup(-2.0) power law. (Auth.)