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1

Intense keV energy polar rain  

SciTech Connect

Polar rain is usually a weak, diffuse precipitation of electrons with intensities below 0.1 erg/cm{sup 2} s and temperatures around 80 eV. Occasionally, it can have much higher fluxes and temperatures. The authors carried out an investigation using an automated search of the DMSP F7 polar cap precipitation over a 1,100-day interval to find all the days with reasonably intense (> 10{sup 6} eV/cm{sup 2} s sr) fluxes in one or more {ge}1-keV electron channels above 80 MLAT. After they eliminated precipitation associated with polar cap arcs, 17 such days were found. For 11 days, the precipitation was at least 0.4 erg/cm{sup 2} s, and on 4 days it reached a few ergs/cm{sup 2} s (for example, n = 0.85/cm{sup 3}, and kT = 2,000 eV). A fairly uniform polar rain over the polar caps at this intensity approximately equals the hemispherical energy flux over the entire auroral oval. Like ordinary polar rain, the keV precipitation occurs in only one hemisphere and is generally accompanied by an often high-density polar rain at more typical energies. No particular association with storms or poststorm quieting was evident in our sample; instead, the results appear to be consistent with the model of Fairfield and Scudder, in that there is an apparent association between intense keV polar rain and low solar-wind densities. The keV electrons were not observed within the cusp proper, futher supporting the concept of polar rain as a special component of the solar-wind electron population. A peristent gap between the poleward edge of auroral electron precipitation and the occurrence of polar rain is observed; the gap is largest at dusk, smaller at dawn, still smaller near midnight, and nonexistent on the dayside. They interpret the field lines poleward of the auroral-oval precipitation and equatorward of polar rain as recently closed field lines.

Newell, P.T.; Meng, Ching-I. (Johns Hopkins Univ., Laurel, MD (USA))

1990-06-01

2

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

PubMed

The X-ray optics group at the Swiss Light Source in co-operation with RIT (Rigaku Innovative Technologies) have investigated seven different multilayer samples. The goal was to find an ideal multilayer structure for the energy range between 6?keV and 20?keV in terms of energy resolution and reflectivity. Such multilayer structures deposited on substrates can be used as X-ray monochromators or reflecting synchrotron mirrors. The measured reflectivities agree with the simulated ones. They cover a reflectivity range from 45% to 80% for energies between 6?keV and 10?keV, and 80% to 90% for energies between 10?keV and 20?keV. The experimentally measured energy resolution of the samples lies between 0.3% and 3.5%. PMID:22898944

Oberta, P; Platonov, Y; Flechsig, U

2012-08-03

3

Radiation Blistering of NB Implanted Sequentially with Helium Ions of Different Energies (3-500 Kev).  

National Technical Information Service (NTIS)

Cold rolled, polycrystalline niobium samples were irradiated at room temperature with exp 4 He exp + 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 app...

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

1976-01-01

4

Complete polarization analysis in the 1keV to 2keV energy range using a high-precision polarimeter  

NASA Astrophysics Data System (ADS)

The Beryl and YB66 crystals are proved to be suitable as analyzers in the energy range from 1.0keV to 2.0keV. The s-component reflectivity (Rs) of Beryl crystal reaches up to 10% with polarizing power Rs/Rp over 1000 at 1.1keV. The free-standing W/B4C multilayer has the phase shift over 5 with moderate transmission up to 1.7keV. The Bragg resonance width of the Beryl crystal is only 350 microradians at 1.1keV, and the incidence angle of the beam onto the crystal needs to be constant within 50 microradians or better. A high-precision polarimeter was used for the polarimetry experiment, and the complete polarization analysis of the APPLE II undulator at 1.1 keV and 1.56keV will be presented.

Wang, Hongchang; Dhesi, Sarnjeet; Bencok, Peter; Steadman, Paul; Maccherozzi, Francesco; Sawhney, Kawal

2013-03-01

5

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

SciTech Connect

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

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

2008-02-25

6

The Stopping Powers of Various Elements for Protons of Energies from 400 to 1050 kev  

Microsoft Academic Search

The proton-stopping powers of the elements nitrogen, neon, argon, krypton, xenon, nickel, and copper are reported in the energy range from 400 kev to 1050 kev. Comparisons are made with results of other experimental work and with theory. The measured stopping powers show a dependence on particle velocity and on the atomic number of the stopping element in general conformity

Arthur B. Chilton; John N. Cooper; James C. Harris

1954-01-01

7

Electron scattering by N 2 and CO at intermediate energies: 110 keV  

Microsoft Academic Search

Semi-empirical total cross sections for electron scattering from N2 and CO in the energy range 110 keV have been obtained by combining transmission-beam measurements for impact energies up to 5 keV with an asymptotic behaviour at high energy according to the Born-Bethe approximation. The influence of the forward electron scattering in our experimental systems has been evaluated by means of

G. Garca; M. Roteta; F. Manero

1997-01-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

9

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

Microsoft Academic Search

The compounds, NaBO, HBO, CdCl and NaCl and their solutions, attenuate gamma rays in addition to neutron absorption. These compounds are widely used in shielding of neutron sources, reactor control and neutron converters. Mass attenuation coefficients of gamma related to saturated solutions of the above four compounds, in energies 1172 keV and 1332 keV have been measured by NaI detector

Jalali; Majid

2006-01-01

10

Channeled and random proton stopping power in the 30-1000 keV energy range  

Microsoft Academic Search

The stopping power of 30- to 1000-keV protons transmitted through silicon in random and channeling (, , and ) directions has been determined. It was found that the stopping power for random and all channeling directions reaches a maximum at about 50 keV. At nearly the same energy the ratio of the channeled-to-random stopping has the maximum value. Present results

A. Carnera; G. Della Mea; A. V. Drigo; S. Lo Russo; P. Mazzoldi; G. G. Bentini

1978-01-01

11

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

Microsoft Academic Search

Thin coatings (~10 m) made from a mixture of polyvinyl alcohol (PVA) and HAuCl4 or PVA and AgNO3 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 ~1015 e cm-2. Samples were characterized by the

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

2007-01-01

12

Energy Dissipation by Ions in the kev Region  

Microsoft Academic Search

At low energies ionic collisions with atoms are largely elastic. Simple theoretical approximations to scattering cross sections, ranges and straggling are derived for power potentials, showing that the scattering is peaked in the forward direction rather than isotropic. Using an approximate universal potential of Thomas-Fermi type a natural measure of range, rho, and of energy, ?, is obtained for all

J. Lindhard; M. Scharff

1961-01-01

13

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

SciTech Connect

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

Saat, Ahmad [Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Hamzah, Zaini; Yusop, Mohammad Fariz; Zainal, Muhd Amiruddin [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia)

2010-07-07

14

X-Ray Detector Calibrations in the 280-Ev to 100-Kev Energy Range.  

National Technical Information Service (NTIS)

The absolute sensitivity for several different types of radiation detectors has been measured using x-rays in the energy range of 280 eV to 100 keV. The photons in this energy range are produced using three separate x-ray-generating facilities. The detect...

J. L. Gaines R. W. Kuckuck R. D. Ernst

1976-01-01

15

Energy loss and angular dispersion of 2-200 keV protons in amorphous silicon  

NASA Astrophysics Data System (ADS)

The energy loss of 2-200 keV protons in thin amorphous silicon foils has been measured for projectiles transmitted in the forward direction and as a function of the exit angle. At the lowest energies, differences of up to 30% with recently published values are observed. Angular effects in the energy loss, at low and high energies, have been investigated. The low-energy results are reproduced by model calculations and Monte Carlo simulations, which indicate that the inelastic energy loss does not show a dependence upon the impact parameter in the low energy region. A fitting formula for the present energy loss values is provided.

Fam, M.; Lantschner, G. H.; Eckardt, J. C.; Arista, N. R.; Gayone, J. E.; Sanchez, E.; Lovey, F.

2002-06-01

16

X-ray source with photon energy 5 keV pumped by laser  

Microsoft Academic Search

Investigation of a monochromatic point x-ray source of photon energy ~5 keV has been carried out. The source was set up using a laser produced aluminium plasma as a cathode and a point-tip titanium anode. Optimum parameters of the diode were determined from experimental measurements of x-ray intensity dependence on laser pulse energy, applied accelerating voltage, and distance between target

Yu V Korobkin; I. V. Romanov; A. A. Rupasov; D. A. Fedin; A. S. Shikanov; A. Moorti; M. Raghuramiah; J. Upadhyay; S. R. Kumbhare; S. Sailaja; V. Arora; P. A. Naik; P. D. Gupta

1999-01-01

17

INVESTIGATION OF U²³⁵ FISSION $gamma$-RAYS IN THE ENERGY REGION UP TO 250 kev  

Microsoft Academic Search

A scintillation spectrometer with a Nal(Tl) crystal and a proportional ; counter connected in coincidence with a fission chamber was used to measure the U\\/; sup 235\\/ fission gamma spectrum in the energy range up to 250 kev. Gamma rays ; with energies of 30 plus or minus 1.5 and 210 plus or minus 10 kev were ; detected, as

V. V. Skliarevskii; D. E. Fomenko; E. P. Stepanov

1957-01-01

18

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

19

IBEX Heliospheric neutral atom energy spectra between 0.01 and 6 keV  

NASA Astrophysics Data System (ADS)

Since early 2009, 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 ~0.5 keV. For the globally distributed population, many neutrals in this energy range are produced by pick up (ionization) of interstellar neutrals in the heliosphere, convection across the termination shock, and a second charge exchange in the heliosheath. With more than 2 years of observations, enough low energy neutral atom measurements have been accumulated to extend IBEX observations down to energies below ~0.5 keV. At these energies, contributions from two additional populations of low energy neutral atoms from the heliosheath become significant. The first population is produced by charge exchange of interstellar neutrals in the heliosheath, beyond the termination shock, and a second charge exchange in the same region. The second population is produced by charge exchange between much slower solar wind ions in the heliosheath and interstellar neutrals. Using the energy overlap of the sensors and observations in different regions near the Earth to identify and remove backgrounds, energy spectra over the entire energy range of IBEX are produced. Compared to spectra at higher energies, neutral atom spectra at lower energies do not vary greatly from location to location in the sky, including in the direction of the IBEX ribbon. Implications for these observations on global heliospheric structure and interactions are discussed.

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

2011-12-01

20

Energy loss of 100-keV hydrogen atoms during grazing scattering from Cu(111)  

SciTech Connect

The energy loss of 100-keV hydrogen atoms scattered under a grazing angle of incidence from a clean and flat Cu(111) surface is studied in coincidence with the number of emitted electrons. From the dependence of the energy loss on the angle of incidence we deduce the position dependent stopping power which shows the same functional dependence but a factor of about 2 higher values than recent calculations. From the number of emitted electrons related to a specific energy loss we reveal processes related to electron emission as dominant channel for energy dissipation of scattered projectiles.

Lederer, S.; Winter, H. [Institut fuer Physik, Humboldt Universitaet zu Berlin, Newtonstrasse 15, D-12489 Berlin-Adlershof (Germany)

2006-05-15

21

183W Resonance Parameter Evaluation in the Neutron Energy Range Up to 5 keV  

SciTech Connect

We generated a preliminary set of resonance parameters for {sup 183}W in the neutron energy range of thermal up to 5 keV. In the analyzed energy range, this work represents a significant improvement over the current resonance evaluation in the ENDF/B-VII.1 library limited up to 2.2 keV. The evaluation methodology uses the Reich-Moore approximation to fit, with the R-matrix code SAMMY, the high-resolution measurements performed in 2007 at the GEel LINear Accelerator (GELINA) facility. The transmission data and the capture cross sections calculated with the set of resonance parameters are compared with the experimental values, and the average properties of the resonance parameters are discussed.

Pigni, Marco T [ORNL; Dunn, Michael E [ORNL; Guber, Klaus H [ORNL

2012-01-01

22

The 93Zr(n,?) reaction up to 8 keV neutron energy  

NASA Astrophysics Data System (ADS)

The (n,?) reaction of the radioactive isotope 93Zr has been measured at the n_TOF high-resolution time-of-flight facility at CERN. Resonance parameters have been extracted in the neutron energy range up to 8 keV, yielding capture widths smaller (14%) than reported in an earlier experiment. These results are important for detailed nucleosynthesis calculations and for refined studies of waste transmutation concepts.

Tagliente, G.; Milazzo, P. M.; Fujii, K.; Abbondanno, U.; Aerts, G.; lvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Audouin, L.; Badurek, G.; Baumann, P.; Be?v?, F.; Belloni, F.; Berthoumieux, E.; Calvio, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapio, C.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrari, A.; Ferreira-Marques, R.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Jericha, E.; Kppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Kossionides, E.; Krti?ka, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lukic, S.; Marganiec, J.; Marrone, S.; Martnez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena, J.; Pretel, C.; Quesada, J.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

2013-01-01

23

HEAO1 observations of HER X-1 at energies above 13 keV  

Microsoft Academic Search

Results from preliminary analysis of HEAO-1 pointing observations of Her X-1 on three days in February 1978 are presented. Pulsed flux is detected up to approximately 70 keV with a clear indication of emission at approximately 60 deV which is above the continuum spectrum extrapolated from lower energies. If this excess emission is interpreted as a spectral line, its intensity

J. L. Matteson; D. E. Gruber; J. A. Hoffman

1978-01-01

24

Scattering of noble gas clusters with energies in the keV range  

SciTech Connect

Noble gas clusters with an average size of several thousand atoms and with energies in the keV range were directed at metal surfaces under small angles of incidence. The scatter products were examined with respect to size, energy, and recoil angle. All observations fit an impact model in which the tangential momentum is preserved during impact, while the normal kinetic energy is converted to cluster heat. The associated temperature rise results in the evaporation of cluster atoms. Small clusters evaporate completely; large clusters are reduced in size. The evaporated atoms continue in a forward direction (together with the residual cluster fragments) and form a well-collimated and energetic atom beam.

Knauer, W. (Hughes Research Laboratories, 3011 Malibu Canyon Road, Malibu, California 90265 (US))

1990-01-01

25

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

SciTech Connect

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

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

2006-07-01

26

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

Microsoft Academic Search

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

G. Garca; M. Roteta; F. Manero; F. Blanco; A. Williart

1999-01-01

27

High order reflectivity of graphite (HOPG) crystals for x ray energies up to 22 keV  

SciTech Connect

We used Kr K{alpha} (12.6 keV) and Ag K{alpha} (22.1 keV) x-rays, produced by petawatt class laser pulses interacting with a Kr gas jet and a silver foil, to measure the integrated crystal reflectivity of flat Highly Oriented Pyrolytic Graphite (HOPG) up to fifth order. The reflectivity in fourth order is lower by a factor of 50 when compared to first order diffraction. In second order the integrated reflectivity decreases from 1.3 mrad at 12.6 keV to 0.5 mrad at 22.1 keV. The current study indicates that HOPG crystals are suitable for measuring scattering signals from high energy x ray sources (E {ge} 20 keV). These energies are required to penetrate through the high density plasma conditions encountered in inertial confinement fusion capsule implosions on the National Ignition Facility.

Doeppner, T; Neumayer, P; Girard, F; Kugland, N L; Landen, O L; Niemann, C; Glenzer, S H

2008-04-30

28

Monochromator harmonic content measurements and calculations at energies above 20 keV  

SciTech Connect

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

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

1991-01-01

29

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

SciTech Connect

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

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

2000-05-01

30

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

SciTech Connect

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

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

1999-06-01

31

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

NASA Astrophysics Data System (ADS)

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

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

2012-07-01

32

Electron Transfer in p-Ar Collisions at keV Energies  

NASA Astrophysics Data System (ADS)

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

Alarcon, F. B.; Martinez, H.; Castillo, F.

2009-03-01

33

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

SciTech Connect

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

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

1997-10-01

34

Mechanical Engineering of a 75-keV Proton Injector for the Low Energy Demonstration Accelerator  

NASA Astrophysics Data System (ADS)

A dc injector capable of 75-keV, 130-mA hydrogen-ion beam operation with a greater than 98% availability is under development for the Low Energy Demonstration Accelerator (LEDA) project at Los Alamos. The low-energy beam transport system (LEBT), incorporating technology developed for the Fusion Materials Irradiation Test (FMIT) accelerator and the Ground Test Accelerator (GTA), uses two solenoid focusing and two steering magnets for beam matching and centroid control at the radio frequency quadrupole (RFQ) matchpoint. All active injector power supplies and controls are located at ground potential. The paper will discuss vacuum considerations, the design of the LEBT, the ion source microwave window and H2 gas flow control, and a beam iris (for continuously variable beam current). Plans for installation of this injector on CW RFQs at Los Alamos will be presented.

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

1997-05-01

35

Antiproton stopping power in He in the energy range 1900 keV and the Barkas effect  

Microsoft Academic Search

The p stopping power in helium from 1 keV kinetic energy is evaluated. Contrary to the effect observed around and below the maximum, Obelix data indicate a p stopping power higher than that for proton, the difference being of the order of 155% at ?700 keV. The result contributes to assert the fundamental difference between p stoppings in the simplest

E. Lodi Rizzini; A. Bianconi; M. P. Bussa; M. Corradini; A. Donzella; M. Leali; L. Venturelli; N. Zurlo; M. Bargiotti; A. Bertin; M. Bruschi; M. Capponi; S. De Castro; R. Don; L. Fabbri; P. Faccioli; B. Giacobbe; F. Grimaldi; I. Massa; M. Piccinini; N. Semprini Cesari; R. Spighi; S. Vecchi; M. Villa; A. Vitale; A. Zoccoli; O. E. Gorchakov; G. B. Pontecorvo; A. M. Rozhdestvensky; V. I. Tretyak; M. Poli; C. Guaraldo; C. Petrascu; F. Balestra; L. Busso; O. Y. Denisov; L. Ferrero; R. Garfagnini; A. Grasso; A. Maggiora; G. Piragino; F. Tosello; G. Zosi; G. Margagliotti; L. Santi; S. Tessaro

2004-01-01

36

Inferring ejection distances and a surface energy profile in keV particle bombardment experiments  

NASA Astrophysics Data System (ADS)

The disappearance cross-sections and kinetic energy distributions of fragment ions sputtered from polystyrene thin films under 12 keV 69Ga+ ion bombardment are measured using a time-of-flight spectrometer. Even though the disappearance cross-sections are often used as an indicator of radial ion beam damage, the derived radii range from 2 to 10 depending on the particular hydrocarbon fragment. Therefore, the disappearance cross-sections cannot be directly related to a single global quantity of damage per incident particle. Likewise, the widths of the measured kinetic energy depend on the particular hydrocarbon fragment. Both the disappearance cross-sections and the widths of the kinetic energy distribution superficially relate to fragment mass but the correlation is not perfect. We develop a hypothesis that the disappearance cross-section and the width of the kinetic energy distribution actually correlate with the ejection radius of the particular fragment. Thus, the kinetic energy distributions provide an estimate of the radial extent of the energy density in the ejection region. Our interpretations are supported by molecular dynamics simulation results. For comparison with previously reported data, our results indicate that the deposited energy profile is 4-5 times narrower than for 72.3 MeV, electronic sputtering of PVDF [Phys. Rev. Lett. 77 (1996) 667].

Delcorte, A.; Segda, B. G.; Garrison, B. J.; Bertrand, P.

2000-11-01

37

High Spatial Resolution STXM at 6.2 keV Photon Energy  

SciTech Connect

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

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

2010-04-06

38

High-resolution integrated germanium Compton polarimeter for the ?-ray energy range 80 keV1 MeV  

Microsoft Academic Search

Parameters which govern the choice of a detection system to measure the linear polarization of ? rays at low energies are discussed. An integrated polarimeter is described which is constructed from a single crystal of germanium. It is a compact planar device with the sectors defined electrically, and which gives an energy resolution in the add-back mode of 1 keV

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

1995-01-01

39

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

SciTech Connect

17-75 keV one- and two-dimensional high-resolution (<10 {mu}m) radiography has been developed using high-intensity short pulse lasers. High energy K{alpha} sources are created by fluorescence from hot electrons interacting in the target material after irradiation by lasers with intensity I{sub L}>10{sup 17} W/cm{sup 2}. High-resolution point projection one- and two-dimensional radiography has been achieved using microfoil and microwire targets attached to low-Z substrate materials. The microwire size was 10 {mu}mx10 {mu}mx300 {mu}m on a 300 {mu}mx300 {mu}mx5 {mu}m polystyrene substrate. The radiography experiments were performed using the Titan laser at Lawrence Livermore National Laboratory. The results show that the resolution is dominated by the microwire target size and there is very little degradation from the plasma plume, implying that the high-energy x-ray photons are generated mostly within the microwire volume. There are enough K{alpha} photons created with a 300 J, 1-{omega}, 40 ps pulse laser from these small volume targets, and that the signal-to-noise ratio is sufficiently high, for single shot radiography experiments. This unique technique will be used on future high energy density experiments at many new high-power laser facilities.

Park, H.-S.; Maddox, B. R.; Hatchett, S. P.; Izumi, N.; Key, M. H.; Le Pape, S.; MacKinnon, A. J.; MacPhee, A. G.; Patel, P. K.; Phillips, T. W.; Remington, B. A.; Tommasini, R.; Town, R. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Giraldez, E. [General Atomics, San Diego, California 92121 (United States); Hudson, L. T. [NIST, Gaithersburg, Maryland 20899 (United States); Seely, J. F. [Naval Research Laboratory, Washington, D.C., 20375 (United States); Workman, J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Brambrink, E. [Laboratoire pour l'Utilisation des Lasers Intenses, Ecole Polytechnique, 91128 Palaiseau Cedex (France)

2008-07-15

40

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

NASA Astrophysics Data System (ADS)

17-75 keV one- and two-dimensional high-resolution (<10 ?m) radiography has been developed using high-intensity short pulse lasers. High energy K? sources are created by fluorescence from hot electrons interacting in the target material after irradiation by lasers with intensity IL>1017 W/cm2. High-resolution point projection one- and two-dimensional radiography has been achieved using microfoil and microwire targets attached to low-Z substrate materials. The microwire size was 10 ?m10 ?m300 ?m on a 300 ?m300 ?m5 ?m polystyrene substrate. The radiography experiments were performed using the Titan laser at Lawrence Livermore National Laboratory. The results show that the resolution is dominated by the microwire target size and there is very little degradation from the plasma plume, implying that the high-energy x-ray photons are generated mostly within the microwire volume. There are enough K? photons created with a 300 J, 1-?, 40 ps pulse laser from these small volume targets, and that the signal-to-noise ratio is sufficiently high, for single shot radiography experiments. This unique technique will be used on future high energy density experiments at many new high-power laser facilities.

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

2008-07-01

41

Multiple scattering of 5-30 keV electrons in evaporated metal films II: Range-energy relations  

Microsoft Academic Search

The ranges of electrons in evaporated films of aluminium, copper, silver and gold have been measured for incident energies E0 between 5 and 20 keV. From electron transmission measurements the maximum range and the extrapolated range were determined. Energy loss measurements gave the mean range and the Thomson-Whiddington range, corresponding to the mean energy Em and the most probable energy

V. E. Cosslett; R. N. Thomas

1964-01-01

42

Measured energy dependence of K-shell photoelectric cross sections for Ti, Fe, Ni, and Zn in the energy region 9-18 keV  

Microsoft Academic Search

Our earlier measurements of the energy dependence of K-shell photoelectric cross sections for Y, Mo, Ag, and Sn in the energy region 18-44 keV have been extended to elements Ti, Fe, Ni, and Zn in the energy range 9<=E<=18 keV. The experiment has been performed under improved experimental conditions using a modified double-reflection geometrical setup and Si(Li) detector in place

K. L. Allawadhi; Raj Mittal; B. S. Sood

1985-01-01

43

Electron energy distributions from multiple ionization in 20-120keV H++Ar collisions  

Microsoft Academic Search

Energy-analyzed secondary electrons from H++Ar collisions at eight proton energies from 20 to 120 keV were detected in coincidence with recoil ions of charge states 1-3. The charge states were distinguished by time-of-flight measurements and the electron energies were analyzed by a newly designed electrostatic analyzer of the low-pass high-pass filter type which has a large (~1.45pi steradian) solid angle

Yang-Soo Chung; M. E. Rudd

1996-01-01

44

Neutron Capture and Fission Cross Section of Americium-243 in the Energy Range from 5 to 250 KeV.  

National Technical Information Service (NTIS)

The neutron capture and subthreshold fission cross section of exp 243 Am was measured in the energy range from 5 to 250 keV using exp 197 Au and exp 235 U as the respective standards. Neutrons were produced via the exp 7 Li(p,n) and the T(p,n) reaction wi...

K. Wisshak F. Kaeppeler

1983-01-01

45

Production of Monoenergetic Neutrons with Energies Between a Few Hundred KeV and 40 MeV.  

National Technical Information Service (NTIS)

Various modes of production of monoenergetic neutrons with energies between a few hundred keV and 40 MeV are presented. Required characteristics for the neutron sources, source reactions - exp 7 Li+p, exp 3 H+p, exp 2 H+d, exp 3 H+d, exp 9 Be+p - and targ...

G. Haouat M. Cance

1980-01-01

46

Calibration system for electron detectors in the energy range from 10 eV to 50 keV  

Microsoft Academic Search

A system for calibrating electron detectors operating in the energy range 10 eV-50 keV is described. The main component of the system is a large area (730 sq cm) monoenergetic electron beam which is tunable with respect to energy. The beam is produced by illuminating a thin gold film deposited onto a quartz flat with ultraviolet light such that photoelectrons

F. J. Marshall; D. A. Hardy; A. Huber; J. Pantazis; J. McGarity; E. Holeman; J. D. Winningham

1986-01-01

47

A Monte Carlo method for calculating the energy response of plastic scintillators to polarized photons below 100 keV  

Microsoft Academic Search

The energy response of plastic scintillators (Eljen Technology EJ-204) to polarized soft gamma-ray photons below 100keV has been studied, primarily for the balloon-borne polarimeter, PoGOLite. The response calculation includes quenching effects due to low-energy recoil electrons and the position dependence of the light collection efficiency in a 20cm long scintillator rod. The broadening of the pulse-height spectrum, presumably caused by

T. Mizuno; Y. Kanai; J. Kataoka; M. Kiss; K. Kurita; M. Pearce; H. Tajima; H. Takahashi; T. Tanaka; M. Ueno; Y. Umeki; H. Yoshida; M. Arimoto; M. Axelsson; C. Marini Bettolo; G. Bogaert; P. Chen; W. Craig; Y. Fukazawa; S. Gunji; T. Kamae; J. Katsuta; N. Kawai; S. Kishimoto; W. Klamra; S. Larsson; G. Madejski; J. S. T. Ng; F. Ryde; S. Rydstrm; T. Takahashi; T. S. Thurston; G. Varner

2009-01-01

48

ANGULAR DISTRIBUTIONS OF AURORAL ELECTRONS IN THE ENERGY RANGE 0.8 TO 16 keV  

Microsoft Academic Search

Auroral particle fluxes have been measured by detectors aboard the low-altitude, polar- orbiting satellite OVI 18. Electron pitch-angle distributions in the energy range 0.8 to 16 kev are presented for a 3-month period in 1969. The distributions at all energies were found to be predominantly isotropic for intensities above a few times 106 (cmsec step key) -x, inde- pendent of

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

1972-01-01

49

A neutron spectrometer for neutrons with energies between 1 eV and 10 keV  

Microsoft Academic Search

Epithermal neutrons with energies between 1 eV and 10 keV are of great interest in neutron capture therapy for treating deep-seated tumors. A new type of neutron spectrometer has been developed to measure neutron spectra in this energy range. Conceptually, this new spectrometer is similar to the Bonner Sphere spectrometry system, in that it has a set of response functions

C. K. Wang; T. E. Blue

1990-01-01

50

Parametrization of the total photon mass attenuation coefficients in the energy range 0.1-1000 keV  

NASA Astrophysics Data System (ADS)

It is convenient to generate mass attenuation coefficients using semi-empirical schemes. The validity of most of the existing schemes is limited to a relatively narrow energy interval (1-40 keV) and their accuracies are poor in some energy regions. In this work, a semi-empirical scheme flexible enough to give a good fit to data in a very wide photon energy range (0.1-1000 keV) was employed. Fitting coefficients for the entire range were obtained by utilizing mass attenuation data from two sources: (1) semi-empirical data of Henke et al. in the low photon energy region, and (2) theoretical values generated with the XCOM code for fitting in the high energy region. The root mean square of the fit is generally less than 0.2% except for energies below 1 keV where the available data are scattered. A computer code for generating mass attenuation coefficients based on the proposed scheme has been developed.

Orlic, I.; Loh, K. K.; Sow, C. H.; Tang, S. M.; Thong, P.

1993-05-01

51

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

SciTech Connect

Natural carbon is well known as reactor structure material and at the same time as one of the most important neutron scattering standards, especially at energies less than 2 MeV, where the neutron total and neutron scattering cross sections are essentially identical. The best neutron total cross section experimental data for natural carbon in the range 1-500 keV have uncertainties of 1-4%. However, the difference between these data and those based on R-matrix analysis and used in the ENDF libraries is evident, especially in the energy range 1-60 keV. Experimental data for total scattering neutron cross sections for this element in the energy range 1-200 keV are scanty. The use of the technique of neutron filtered beams developed at the Kyiv Research Reactor makes it possible to reduce the uncertainty of the experimental data and to measure the neutron scattering cross sections on natural carbon in the energy range 2-149 keV with accuracies of 3-6%. Investigations of the neutron scattering cross section on carbon were carried out using 5 filters with energies 2, 3.5, 24, 54 and 133 keV. The neutron scattering cross sections were measured using a detector system covering nearly 2{pi}. The detector consisting of {sup 3}He counters (58 units), was located just above the carbon samples. The {sup 3}He counters (CHM-37, 7 atm, diameter =18 mm, L=50 cm) are placed in five layers (12 or 11 in each layer). To determine the neutron scattering cross section on carbon the relative method of measurement was used. The isotope {sup 208}Pb was used as the standard. The normalization factor, which is a function of detector efficiency, thickness of the carbon samples, thickness of the {sup 208}Pb sample, geometry, etc., for each sample and for each filter energy has been obtained through Monte Carlo calculations by means of the MCNP4C code. The results of measurements of the neutron scattering cross sections at reactor neutron filtered beams with energies in the range 2-133 keV on carbon samples together with the known experimental data from database EXFOR/CSISRS and ENDF libraries are presented.

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

2006-06-14

52

Multipoint observations of ions in the 30-160 keV energy range upstream of the Earth's bow shock  

NASA Astrophysics Data System (ADS)

We use multipoint observation data by Cluster during time periods when the interspacecraft separation distance was between 1 and 1.5 Earth radii in order to study the physical processes related to diffuse ions at <200 keV/e. For our analysis we use data from the Research with Adaptive Particle Imaging Detectors (RAPID) experiment onboard Cluster SC1 and SC3. We determine spatial ion density gradients by using proton intensities in the 27.7-159.7 keV energy range and helium intensities in the 137.8-235.1 keV energy range as a function of distance from the bow shock along the magnetic field. Our results show that the diffuse ions are subject to diffusive transport and the ion partial densities decrease exponentially with increasing distance from the bow shock. By complementing RAPID data with Cluster Ion Spectrometry measurements at lower energies (from 10 to 32 keV) from the same upstream ion event we find that the e-folding distance of energetic ion density increases almost linearly with energy. This effect is also seen in the hardening of the particle spectra with increasing distance from the bow shock. We determine the spatial diffusion mean free path and the diffusion coefficient as a function of ion energy by assuming that upstream diffusion is balanced by downstream convection.

Kronberg, E. A.; Kis, A.; Klecker, B.; Daly, P. W.; Lucek, E. A.

2009-03-01

53

"Sweet spot" for endoleak detection: Optimizing contrast to noise using low keV reconstructions from fast-switch kVp dual energy CT  

PubMed Central

Objective To assess endoleak detection and conspicuity using low keV monochromatic reconstructions of single source (fast-switch kVp) dual energy datasets. Methods With IRB approval, multiphasic dual energy CT scans for aortic endograft surveillance were retrospectively reviewed for 39 patients. Two abdominal radiologists each performed two separate reading sessions, at 55 keV and standard 75 keV reconstruction, respectively. Readers tabulated endoleak presence, conspicuity on 1-5 scale, and type overall and in arterial and venous phases. Originally dictated reports in medical records were used as gold standard. Results Original dictations identified 19 endoleaks (9 abdominal and 10 thoracic), 13 of which were Type II. The blinded readers (R1 and R2) exhibited good to very good intraobserver and interobserver agreement. Endoleak detection was higher at 55 keV than 75 keV (sensitivity 100% (CI 82.4-100.0%) and 84.2% (CI 60.4-96.6%)at 55 keV vs. 79% (CI 54.4-94.0%)and 68.4% (CI 43.5-87.4%) at 75 keV in venous phase). Further, endoleak conspicuity ratings (where original dictation showed positive leak) were higher at 55 keV than 75 keV, which was a significant difference for R2 in the overall ratings (p=.03) and for both readers in the venous phase ratings (R1:p=.01; R2: p=.004). There was no difference in endoleak type characterization between the keV levels. Conclusion Sensitivity for endoleak detection and overall endoleak conspicuity ratings were both higher at 55 keV than 75 keV, favoring the inclusion of a lower energy monochromatic reconstruction for endoleak surveillance protocols with dual energy CT.

Kaza, Ravi K; Liu, Peter S; Quint, Leslie E; Khalatbari, Shokoufeh H; Platt, Joel F

2012-01-01

54

Field-ionizing lens system for the detection of high Rydberg states in multicharged ions of keV energies  

Microsoft Academic Search

A new detector for state analysis of multicharged ions, excited in high Rydberg states, at kinetic energies of the order of keV is described. It is composed of a field-ionizing lens system (FILS), associated with two electrostatic spectrometers; the first one, in front of the FILS, selects the q-times charged excited ions of interest, and the second one, behind the

A. Pesnelle; H. J. Andr

1997-01-01

55

A neutron spectrometer for neutrons with energies between 1 eV and 10 keV  

NASA Astrophysics Data System (ADS)

Epithermal neutrons with energies between 1 eV and 10 keV are of great interest in neutron capture therapy for treating deep-seated tumors. A new type of neutron spectrometer has been developed to measure neutron spectra in this energy range. Conceptually, this new spectrometer is similar to the Bonner Sphere spectrometry system, in that it has a set of response functions which peak at various positions on the logarithmic energy scale. Therefore, by collecting a set of count rates, one can unfold the neutron spectrum. The performance of the spectrometer was tested in an experiment, and the associated unfolding technique was tested numerically. The results were satisfactory.

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

1990-05-01

56

Mass attenuation coefficient of the Earth, Moon and Mars samples over 1keV-100GeV energy range.  

PubMed

This work presents the calculation of the mass attenuation coefficient (micro) of lunar, Martian and terrestrial samples in function of the energy. WinXCOM software was employed to determine the micro values for the samples in the range from 1 keV to 100 GeV. The obtained values were practically the same for energies larger than 100 keV, but marked differences among the samples were observed for energies below 25 keV, which is the energy range of interest for the XRF system used in space probes. PMID:16725330

Camargo Moreira, Anderson; Roberto Appoloni, Carlos

2006-05-24

57

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

SciTech Connect

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

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

1988-01-01

58

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

Microsoft Academic Search

17-75 keV one- and two-dimensional high-resolution (1017 W\\/cm2. High-resolution point projection one- and two-dimensional radiography has been achieved using microfoil and microwire targets attached to low-Z substrate materials. The microwire size was 10 mum10 mum300 mum on a 300 mum300 mum5 mum polystyrene substrate. The radiography experiments were performed using the Titan laser at Lawrence Livermore National Laboratory. The results

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

2008-01-01

59

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

NASA Astrophysics Data System (ADS)

Performance of Ni/C, Ni/B4C, Mo/B4C and W/B4C multilayers in the energy range E > 8 keV is considered by simulation of x-ray reflectivity and resolution of 1st order Bragg reflection at three different photon energies. The results indicate, that Ni/C and Ni/B4C multilayers show highest theoretical reflectivities of R > 80% for Cu K(alpha) - radiation and also above the Mo K-edge (E equals 20.04 keV) at 30 keV. For Mo K(alpha) -radiation a reflectivity of R > 90% can be achieved by the use of Mo/B4C multilayers. For applications, where period thicknesses d < 3 nm and high reflectivities are required W/B4C multilayers can be used. Theoretical values are compared with X-ray reflectometry results, which were executed at 75 period Ni/C, Ni/B4C and Mo/B4C multilayers, fabricated by pulsed laser deposition (PLD) technology on Si substrates. Amorphous or nanocrystalline structures of single layers, smoothest interfaces and high reproducibility of single layer thickness across the entire layer stack are the results of this high precision PLD process.

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

2000-11-01

60

Energy spectra of ~170-360 keV electron microbursts measured by the Korean STSAT-1  

NASA Astrophysics Data System (ADS)

Energy spectra of electron microbursts in the energy range 170-360 keV have been measured in the outer radiation zone by the low-altitude (680 km), polar-orbiting Korean satellite STSAT-1. These electrons are the lower energy population of relativistic microbursts. Our observations show microburst energy spectra of precipitated electrons inside the loss cone (precipitated) have higher e-folding energies during disturbed times than quiet times. The loss cone at these energies is empty except when microbursts abruptly appear and fill the loss cone in less than 50 msec. This fast pitch angle diffusion requires diffusion coefficients larger than ~3.5 10-2 rad2/sec, while ~1.5 10-5 rad2/sec was proposed by a wave particle interaction theory. The source of microbursts remains unknown as our observations are not adequately explained by wave and particle resonant interaction models.

Lee, J.-J.; Parks, G. K.; Min, K. W.; Kim, H. J.; Park, J.; Hwang, J.; McCarthy, M. P.; Lee, E.; Ryu, K. S.; Lim, J. T.; Sim, E. S.; Lee, H. W.; Kang, K. I.; Park, H. Y.

2005-07-01

61

Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV  

SciTech Connect

Mass energy-transfer (Mu(sub u)/Rho) and mass energy-absorption coefficients (Mu(sub en)/Rho) are tabulated in units of (sqcm/g) for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general dosimetric interest. Cross sections for photo-effect, incoherent scattering, pair and triplet production are those compiled or generated by the National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards). Corrections are included for in-flight positron annihilation, previously not applied in NIST calculations for energies above 10 MeV.

Higgins, P.D.; Attix, F.H.; Hubbell, J.H.; Seltzer, S.M.; Berger, M.J.

1991-11-01

62

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

Microsoft Academic Search

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

S. R. Manohara; S. M. Hanagodimath

2007-01-01

63

Structural characterization of negatively charged glycosaminoglycans using high-energy (50-150 keV) collisional activation  

NASA Astrophysics Data System (ADS)

Anionic glycosaminoglycan mono- and disaccharides (IVA, IH and IS) were subjected to very high-energy collisions (50-150 keV ion kinetic energy prior to collision) with Neon gas in an accelerator mass spectrometer, to explore the possibility of using this method to structurally characterize anionic sugars. Experiments were also conducted for the Na+.IH2- and Na+.IS3- sodiated complexes. This high-energy ion collision technique is applied here to sugars for the first time. Low-energy collision-induced dissociation (CID) measurements obtained using resonance excitation in a quadrupole ion-trap are presented for comparison. The high-energy measurements produce a rich variety of fragment ions, illustrating the general utility of the technique for providing detailed information for structurally characterizing sugar ions. We discuss the observed fragmentation patterns with reference to the known fragmentation behavior of small gas-phase monoanions, multiply charged anions and cation-dianion complexes.

Taylor, Christopher J.; Burke, Ruth M.; Wu, Bohan; Panja, Subhasis; Nielsen, Steen Brndsted; Dessent, Caroline E. H.

2009-08-01

64

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

SciTech Connect

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.

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

2007-12-10

65

Absolute calibration of image plates for electrons at energy between 100 keV and 4 MeV.  

PubMed

We measured the absolute response of image plate (Fuji BAS SR2040) for electrons at energies between 100 keV and 4 MeV using an electron spectrometer. The electron source was produced from a short pulse laser irradiated on solid density targets. This paper presents the calibration results of image plate photon stimulated luminescence per electron 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 energy depositions at these angles. These provide a complete set of tools that allows extraction of our absolute calibration to other spectrometer setting at this electron energy range. PMID:18377001

Chen, Hui; Back, Norman L; Bartal, Teresa; Beg, F N; Eder, David C; Link, Anthony J; MacPhee, Andrew G; Ping, Yuan; Song, Peter M; Throop, Alan; Van Woerkom, Linn

2008-03-01

66

Amorphization of Si(001) by ultra low energy (0.5-5keV) ion implantation observed with high-resolution RBS  

NASA Astrophysics Data System (ADS)

The process of amorphization of Si(001) by ultra low energy (0.5keV B+ and 5keV Si+) ion implantation is investigated using high-resolution RBS/channeling with a depth resolution better than 1nm. In contrast to observations at higher implantation energies, amorphization by the ultra low energy ion implantation appears to proceed from the SiO2/c-Si interface. The threshold dose for amorphization is determined to be ~1x1015cm-2 for 0.5keV B+ and ~1.5x1014cm-2 for 5keV Si+. Comparison of the experimental results with TRIM simulations suggests that the SiO2/c-Si interface behaves as a nucleation site for amorphization.

Kimura, K.; Agarwal, A.; Toyofuku, H.; Nakajima, K.; Gossmann, H.-J.

1999-01-01

67

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

NASA Astrophysics Data System (ADS)

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.

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

2009-09-01

68

NEUTRON ACTIVATION AT 195 kev  

Microsoft Academic Search

Neutron activation cross sections were measured at 195 kev (50 kev ; energy spread) for about 30 isotopes, bY absolute gamma counting. Absolute ; calibration was effected by determining the RdTh-DO neutron source ; strength with a flat response 4 pi graphite sphere neutron counter, and ; irradiating indium in the form of a thin, uniform, spherical shell. The results

W. S. Lyon; R. L. Macklin

1959-01-01

69

Nuclear and electronic energy loss by 1 keV to 60 keV ions in silicon : comparison of measurement to SRIM  

SciTech Connect

Comparison of TRIM simulations with measurements of the energy lost to electronic and nuclear stopping processes using 1 00% internal carrier collection efficiency silicon photodiodes shows a large, systematic overestimation by TRIM of electronic energy loss.

Funsten, H. O. (Herbert O.); Harper, R. W. (Ronnie W.); Ritzau, S. M. (Stephen M.); Korde, R. (Raj)

2003-01-01

70

Understanding energy loss in large-angle scattering of keV electrons from Ar and Ne  

SciTech Connect

We present measurements of the spectra of electrons with energy between 0.6 and 2.25 keV elastically and inelastically scattered from Ar and Ne over large angles (from 3 deg. to 135 deg.). The intensity of the first loss feature [np{yields}(n+1)s], relative to that of the elastic peak, was determined and compared with the results of relativistic distorted-wave calculations (for the energy loss part) and a relativistic optical potential method (for the elastic peak). Good agreement was found. The distorted-wave calculations are compared with first Born calculations. At small angles, both theories coincide and estimates of the optical oscillator strength are obtained. However, at large angles, the first Born approximation predicts negligible intensity, in strong contrast to the distorted-wave theory and the experimental data. The implications of these results for the interpretation of measurements of the generalized oscillator strength are discussed.

Vos, M.; McEachran, R. P. [Atomic and Molecular Physics Laboratories, Research School of Physics and Engineering, Australian National University, Canberra ACT (Australia); Cooper, G.; Hitchcock, A. P. [Department of Chemistry and Chemical Biology, McMaster University, Hamilton, Ontario, L8S 4M1 (Canada)

2011-02-15

71

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

NASA Astrophysics Data System (ADS)

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

Moldovan, G.; Matheson, J.; Derbyshire, G.; Kirkland, A.

2008-11-01

72

Understanding energy loss in large-angle scattering of keV electrons from Ar and Ne  

NASA Astrophysics Data System (ADS)

We present measurements of the spectra of electrons with energy between 0.6 and 2.25 keV elastically and inelastically scattered from Ar and Ne over large angles (from 3 to 135). The intensity of the first loss feature [np?(n+1)s], relative to that of the elastic peak, was determined and compared with the results of relativistic distorted-wave calculations (for the energy loss part) and a relativistic optical potential method (for the elastic peak). Good agreement was found. The distorted-wave calculations are compared with first Born calculations. At small angles, both theories coincide and estimates of the optical oscillator strength are obtained. However, at large angles, the first Born approximation predicts negligible intensity, in strong contrast to the distorted-wave theory and the experimental data. The implications of these results for the interpretation of measurements of the generalized oscillator strength are discussed.

Vos, M.; McEachran, R. P.; Cooper, G.; Hitchcock, A. P.

2011-02-01

73

Importance of L=2 components in the 2H(d,n)3He reaction for deuteron energies below 350 keV  

Microsoft Academic Search

Angular distributions for the 2H(d,n)3He reaction have been calculated for incident deuteron energies between 19.5 keV and 349 keV. Model calculations are performed using the generalised R-matrix methodology of Lane and Robson (1966) and additional distorted wave Born approximation terms to describe the long-range spatial contribution to the cross section. Model results are consistent with the experimental prediction of Galloway

J. J. Bevelacqua

1981-01-01

74

(239)Pu neutron resonance parameters revisited and covariance matrix in the neutron energy range from thermal to 2.5 keV  

SciTech Connect

To obtain the resonance parameters in a single energy range up to 2.5 keV neutron energy and the corresponding covariance matrix, a reevaluation of 239Pu was performed with the analysis code SAMMY. The most recent experimental data were analyzed in the energy range thermal to 2.5 keV. The experimental data were renormalized, aligned on a common energy scale, and corrected for residual background. Average neutron transmission and cross sections calculated with the new resonance parameters were compared to the corresponding experimental data and to ENDF/B-VI.

Derrien, Herve [ORNL; Leal, Luiz C [ORNL; Larson, Nancy M [ORNL

2008-01-01

75

Measurements of Neutron Capture Cross Sections for DY Isotopes in the Energy Region from 10 TO 90 KEV  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of Dy isotopes (161Dy, 162Dy, 163Dy, and 164Dy) have been measured in the neutron energy range from 10 to 90 keV using the 3-MV Pelletron accelerator of the Research Laboratory for Nuclear Reactors at the Tokyo Institute of Technology. Pulsed keV neutrons were produced from the 7Li(p, n)7Be reaction by bombarding the lithium target with the 1.5-ns bunched proton beam from the Pelletron accelerator. The incident neutron spectrum on a capture sample was measured by means of a TOF method with a 6Li-glass detector. Capture ?-rays were detected with a large anti-Compton NaI(Tl) spectrometer, employing a TOF method. A pulse-height weighting technique was applied to observed capture ?-ray pulse-height spectra to derive capture yields. The capture cross sections were obtained by using the standard capture cross sections of 197Au. The present results were compared with the previous measurements and the evaluated values of ENDF/B-VI.

Kim, G. N.; Min, Y. G.; Ro, T. I.; Kim, H. D.; Ahn, J. K.; Mizuno, S.; Ohsaki, T.; Igashira, M.

2003-06-01

76

High-resolution integrated germanium Compton polarimeter for the {gamma}-ray energy range 80 keV--1 MeV  

SciTech Connect

Parameters which govern the choice of a detection system to measure the linear polarization of {gamma} rays at low energies are discussed. An integrated polarimeter is described which is constructed from a single crystal of germanium. It is a compact planar device with the sectors defined electrically, and which gives an energy resolution in the add-back mode of 1 keV at 300 keV. Its performance is demonstrated in a series of calibration measurements using both unpolarized radiation from radioactive sources and polarized {gamma} rays from the {sup 168}Er({alpha},2{ital n}){sup 170}Yb reaction at {ital E}{sub {alpha}}=25 MeV. Polarization measurements at energies as low as 84 keV have been achieved, where the sensitivity was 0.32{plus_minus}0.09. The sensitivity, efficiency, and energy resolution are reported. Our results indicate that energy resolution should be included in the definition of the figure of merit and we relate the new definition to earlier work. The comparisons show the advantages of the present design in the energy range below 300 keV and its competitiveness up to 1500 keV. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

Sareen, R.A.; Urban, W.; Barnett, A.R.; Varley, B.J. [Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

1995-06-01

77

Energy recovery experiments with a powerful 100 keV D- based neutral beam injector  

Microsoft Academic Search

Energy recovery experiments have been conducted for the first time with a negative ion based neutral beam injector. A new type of energy recovery system was utilized, which: (i) separates electrostatically the neutrals and charged components of the beam at the exit of the neutralizer; (ii) decelerates the residual unneutralized negative ions; (iii) prevents secondary emission of electrons from the

Michele Fumelli; Franois Jequier; Jrme Pamla; Masaya Hanada; Yoshikazu Okumura; Kazuhiro Watanabe

1992-01-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

79

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

80

Inelastic processes in K+-He collisions in energy range 0.710 keV  

NASA Astrophysics Data System (ADS)

Absolute cross sections for charge exchange, ionization, stripping, and excitation in K+-He collisions were measured in the ion energy range 0.710 keV. The experimental data and the schematic correlation diagrams are used to analyze and determine the mechanisms for these processes. The increase of the excitation probability of inelastic channels with the angle of scattering is revealed. An exceptionally highly excited state of He is observed and a peculiarity for the excitation function of the resonance line is explained. The intensity ratio for the excitation of the K II ?=60.1 nm and ?=61.2 nm lines is 5:1, which indicates the high probability for excitation of the singlet resonance level 1P1 compared to the triplet level 3P1. The similarity of the population of the 4p state of the potassium ion and atom as well as the anomalously small values of the excitation cross sections are explained.

Lomsadze, R. A.; Gochitashvili, M. R.; Kezerashvili, R. Ya.; Mosulishvili, N. O.; Phaneuf, R.

2013-04-01

81

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

SciTech Connect

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

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

2008-04-22

82

Optimum condition of efficiency functions for HPGe ?-ray detectors in the 121-1408 keV energy range  

NASA Astrophysics Data System (ADS)

The optimum condition of three commonly used functions in the Genie 2000 ? spectra analysis software have been studied in the 121-1408 keV energy range. The three functions are applied for fitting the full-energy peak efficiency of the HPGe gamma-ray detector. A detailed procedure to obtain the optimum condition is described. The HPGe detector is calibrated at 11 cm by three radioactive sources of point form (152Eu, 137Cs, 60Co) providing 11 energy peaks. After data processing, results shows that the three functions used in the Genie 2000 gamma spectra analysis software fit best at orders 3-5. Lastly the standard radioactive source 133Ba is chosen to validate the results. Differences between the standard activity of 133Ba and the result obtained from the fitting functions are below 1.5%. Therefore the optimum orders of the three functions used in the Genie 2000 ? spectra analysis software are 3-5 with the 11 energy peaks.

Chen, Zhi-Lin; Song, Guo-Yang; Mu, Long; Wang, He-Yi; Xing, Shi-Xiong; Guo, Hong-Bo; Liao, Zhen-Xing; Chen, Ping; Hua, Sheng

2010-05-01

83

Thermoluminescent Response of Tld-100 to Low Energy Electrons (5 Kev to 30 Kev) and the Effect of Annealing in Various Atmospheres.  

National Technical Information Service (NTIS)

Previous investigations of the thermoluminescent response of the dosimetry phosphor LiF (TLD-100) to low energy electrons have given veried estimates of its sensitivity. In addition, several investigators have noted that the glow curve shape of TLD-100 ir...

J. B. Lasky P. R. Moran

1973-01-01

84

Experimental study of the characteristics of D- and H- beams produced by a multi-hole multi-ampere accelerator at energies up to 105 keV  

Microsoft Academic Search

The acceleration of D- and H- beams has been studied at energies of up to 105 keV, with currents of the order of 2 A, in multi-second pulses. The optimum extraction voltage has been studied as a function of the beam energy and current. The perveance of the negative ion accelerator has been measured over a wide range of operating

Jrme Pamla; Michele Fumelli; Franois Jequier; Alain Simonin; Masaya Hanada; Yoshikazu Okumura; Kazuhiro Watanabe

1992-01-01

85

High-resolution integrated germanium Compton polarimeter for the gamma-ray energy range 80 keV1 MeV  

Microsoft Academic Search

Parameters which govern the choice of a detection system to measure the linear polarization of γ rays at low energies are discussed. An integrated polarimeter is described which is constructed from a single crystal of germanium. It is a compact planar device with the sectors defined electrically, and which gives an energy resolution in the add-back mode of 1 keV

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

1995-01-01

86

The low energy particle detector sled (~30 keV3.2 MeV) and its performance on the phobos mission to mars and its moons  

Microsoft Academic Search

A low energy particle detector system (SLED) is described which was designed to measure the flux densities of electrons and ions in the energy range from ~30 keV to a few MeV in (a) the varying solar aspect angles and temperatures pertaining during the Cruise Phase of the Phobos Mission and (b) in the low temperature environment (reaching -25 C)

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

1990-01-01

87

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

SciTech Connect

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

Kostroun, V.O.

1992-07-05

88

Development of multilayer laminar-type diffraction gratings to achieve high diffraction efficiencies in the 1-8 keV energy region  

SciTech Connect

W/C and Co/SiO2 multilayer gratings have been fabricated by depositing a multilayer coating on the surface of laminar-type holographic master gratings. The diffraction efficiency was measured by reflectometers in the energy region of 0.6-8.0 keV at synchrotron radiation facilities as well as with an x-ray diffractometer at 8.05 keV. The Co/SiO2 and W/C multilayer gratings showed peak diffraction efficiencies of 0.47 and 0.38 at 6.0 and 8.0 keV, respectively. To our knowledge, the peak efficiency of the W/C multilayer grating is the highest measured with hard x rays. The diffraction efficiency of the Co/SiO2 multilayer gratings was higher than that of the W/C multilayer grating in the energy range of 2.5-6.0 keV. However, it decreased significantly in the energy above the K absorption edge of Co(7.71 keV). For the Co/SiO2 multilayer grating, the measured diffraction efficiencies agreed with the calculated curves assuming a rms roughness of?1 nm.

Ishino, Masahiko; Heimann, Philip A.; Sasai, Hiroyuki; Hatayama, Masatoshi; Takenaka, Hisataka; Sano, Kazuo; Gullikson, Eric M.; Koike, Masato

2006-09-10

89

Observation of particles with energy over 100 keV in z-pinch device  

NASA Astrophysics Data System (ADS)

The high energy particles were produced at the implosion of a tungsten wire array z-pinch onto a deuterated fiber at the S-300 device (4 MA, 700 kV, 100ns; RRC Kurchatov Institute, Moscow). The FWHM of the signal in spectral window 270 eV was 35-60 ns. The hard x-rays and neutrons with the FWHM (10-30) ns were produced during the soft x-ray maximum. The neutron yield from the D-D reaction reached 108 per shot. The mean energy of neutrons determined from time-of-flight analysis in the direction back to the anode, back to the cathode and side-on was in the range of (2.2-3.1) MeV and a time delay between neutron and hard x-rays maximum was in the range of (5-20)ns.

Kubes, Pavel; Klir, Daniel; Kravarik, Jozef; Bakshaev, Yuriy L.; Blinov, Peter I.; Chernenko, Andrey S.; Danko, Sergey A.; Hongchun, Cai; Ivanov, Michail I.; Korolev, Valery D.; Korelsky, Alexander V.; Kravchenko, Elena V.; Shaskov, Andrey Y.; Ustroev, Genady I.

2005-03-01

90

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

91

A silicon <111> phase retarder for producing circularly polarized x-rays in the 2.1-3 keV energy range  

NASA Astrophysics Data System (ADS)

Circularly polarized synchrotron light is routinely used to study different material properties but is difficult to generate reproducibly below 3.1 keV. We present data from a 5 ?m Si <111> phase retarder (PR) designed to operate in the 2.1 to 3 keV energy range. Measurements were performed at the Pd L3 edge to enable direct comparison with a conventional diamond PR. The degree of circular polarization was ascertained indirectly by recording the resonant specular reflectivity from a [Fe(2 ML)/Pd(15 ML)]20 multilayer. Our findings show that such a device can be used to extend the usable energy capability of PR technology down to 2.1 keV.

Bouchenoire, Laurence; Morris, Richard J. H.; Hase, Thomas P. A.

2012-08-01

92

Energy and intensity distributions of 279 keV multiply scattered photons in bronze - an inverse response matrix approach  

NASA Astrophysics Data System (ADS)

An inverse response matrix converts the observed pulse-height distribution of a NaI(Tl) scintillation detector to a true photon spectrum. This also results in extraction of intensity and energy distributions of multiply scattered events originating from interactions of 279 keV photons with thick targets of bronze. The observed pulse-height distributions are a composite of singly and multiply scattered events in addition to bremmstrahlung originating from slowing down of Compton and photo-electrons in thick targets. To evaluate the contribution of multiply scattered events, the spectrum of singly scattered events contributing to inelastic Compton peak is reconstructed analytically. The optimum thickness (saturation depth), at which the number of multiply scattered events saturate, has been evaluated in different energy bin meshes chosen for scintillation detector response unfolding. Monte Carlo calculations based upon the package developed by Bauer and Pattison (Compton scattering experiments at the HMI (1981), HMI-B 364, pp. 1-106) supports the present experimental results.

Singh, Manpreet; Singh, Bhajan; Sandhu, B. S.

2008-01-01

93

Formation of doubly charged potassium ions in K+-He and K+-Kr collisions in the 1-10 keV energy range  

NASA Astrophysics Data System (ADS)

We present measurements of the absolute total cross-sections for the formation of K2+ ions, the production of free electrons and the excitation of K+, Ko, He and Kr particles in K+-He and K+-Kr collisions at moderate energies (1-10 keV). The formation mechanisms of K2+ ions are discussed.

Gochitashvili, M.; Kikiani, B.; Lomsadze, R.

2003-05-01

94

Measurement of the exp 6 Li (N, alpha )T Cross-Section over the Energy Range 150 Kev to 3.9 Mev.  

National Technical Information Service (NTIS)

A measurement has been made of the exp 6 Li(n, alpha )t cross section sigma/sub n alpha/ in the energy range 160 keV to 3.9 MeV by calibrating a exp 6 Li semiconductor sandwich spectrometer against counters of known relative efficiencies. As a result of t...

P. J. Clements I. C. Rickard

1972-01-01

95

Silicon and polyimide filters for radiation with quantum energies 0. 1-1. 5 keV  

SciTech Connect

The authors prepared membranes of Si and polyimide (C/sub 22/O/sub 5/N/sub 2/H/sub 10/)n with thickness less than 1 submicron with areas not less than 3 x 3 mm. Such membranes can be used either directly as filters which are placed in front of the radiation detector or as substrates for the deposition on them of materials with the needed properties. The authors used laser-induced sources to conduct the filter experiments. Silicon has substantial absorption in the energy region 0.1-0.5 keV; therefore, the authors also studied the possibility of forming a patterned window in the membrane in the polymer layer on the substrate after its development. The polyimide filter in this case lies in front of the Si filter. The use of polyimide allows extraction of the needed region of the spectral distribution of the radiation. During preparation of Si membranes as the base and body for the membrane, the authors chose substrates of Si with orientation along the normal to the substrate. The choice of this orientation was due to the subsequent use of etch processes. The Si substrates were doped from both sides with boron to a concentration of 5 x 10/sup 19/cm/sup -3/ by diffusion into the wafer.

Bokov, Yu.S.; Kas'yanov, Yu.S.; Korsakov, V.S.; Leonov, Yu.S.; Mishachev, V.I.

1986-05-01

96

Iridium optical constants from synchrotron reflectance measurements over 0.05- to 12-keV x-ray energies  

NASA Astrophysics Data System (ADS)

We present optical constants derived from synchrotron reflectance measurements of iridium-coated X-ray witness mirrors over 0.05-12 keV, relevant to the Chandra X-ray Observatory effective area calibration. In particular we present for the first time analysis of measurements taken at the Advanced Light Source Beamline 6.3.2 over 50-1000 eV, Chandra's lower-energy range. Refinements to the currently tabulated iridium optical constants (B. L. Henke et al., At. Data Nucl. Data Tables 54, 181-343, 1993 and on the Web at http://www-cxro.lbl.gov/optical_constants/) will become important as the low-energy calibration of Chandra's X-ray detectors and gratings are further improved, and as possible contaminants on the Chandra mirror assembly are considered in the refinement of the in-flight Ir absorption edge depths. The goal of this work has been to provide an improved tabulation of the Ir optical constants over the full range of Chandra using a self-consistent mirror model, including metallic layers, interface roughness, contaminating overlayer, and substrate. The low-energy data present us with a considerable challenge in the modeling of the overlayer composition, as the K-absorption features of C, O, and N are likely to be present in the ~10A overlayer. The haphazard contamination and chemical shifts may significantly affect optical constants attributed to this overlayer, which will distort the iridium optical constants derived. Furthermore, the witness mirror contamination may be considerably different from that deposited on the flight optics. The more complex modeling required to deal with low-energy effects must reduce to the simpler model applied at the higher energies, which has successfully derived optical constants for iridium in the higher energy range, including the iridium M-edges, already used in the Chandra calibration. We present our current results, and the state of our modeling and analysis, and our approach to a self-consistent tabulation.

Graessle, Dale E.; Soufli, Regina; Nelson, Art J.; Evans, Cheryl L.; Aquila, Andrew L.; Gullikson, Eric M.; Blake, Richard L.; Burek, Anthony J.

2004-10-01

97

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

PubMed

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

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

2010-04-01

98

Vela X-1 observations in different orbital phases. Phase-resolved spectra in the 0.2 - 10 keV energy band and pulse profile analysis.  

NASA Astrophysics Data System (ADS)

Vela X-1 was pointed by BeppoSAX satellite during the Science Verification Phase (SVP) and in the framework of Observational Programs. The lightcurves of these observations are quite complex and includes dips and eclipses. We performed detailed phase-resolved spectral analysis in the 0.2 - 10 keV energy band. Spectral parameters as iron line energy, width and low energy absorption show clear dependence on the pulse-phase. Pulse profile structure is strongly dependent on the energy and becomes complex in the low energy part of the spectrum.

Del Sordo, S.; Orlandini, M.; Parmar, A.; Santangelo, A.; Segreto, A.; Dal Fiume, D.

2000-10-01

99

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

SciTech Connect

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

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

2010-10-15

100

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

101

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

NASA Astrophysics Data System (ADS)

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

Midgley, S. M.

2005-03-01

102

Proton-recoil detectors for time-of-flight measurements of neutrons with kinetic energies from some tens of keV to a few MeV  

NASA Astrophysics Data System (ADS)

For experiments at the superconducting electron accelerator ELBE, where neutrons in the kinetic energy region from some tens of keV to a few MeV will be produced by bremsstrahlung, neutron-time-of-flight detectors have been developed. These detectors are made from the plastic scintillator material EJ-200. Efficiency calibration showed more than 10% efficiency for kinetic energies down to 30 keV. The calibration was done at the accelerator facility for fast neutron research at Physikalisch-Technische Bundesanstalt in Braunschweig, using pulsed quasi-monoenergetic neutron fields with a well-determined fluence. The low detection threshold was obtained by coincident readout of two Hamamatsu R2059-01 photomultiplier tubes per scintillator and by triggering just below the single-photo-electron peak of these photomultiplier tubes, which additionally gives a well-reproduceable detection threshold.

Beyer, R.; Grosse, E.; Heidel, K.; Hutsch, J.; Junghans, A. R.; Klug, J.; Lgrdy, D.; Nolte, R.; Rttger, S.; Sobiella, M.; Wagner, A.

2007-06-01

103

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

SciTech Connect

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

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

2011-09-15

104

Measurements of photon-atom elastic scattering cross-sections in the photon energy range 1 keV to 4 MeV  

Microsoft Academic Search

We review the current status of measurements of photon-atom elastic scattering cross-sections for the restricted photon energy range 1 keV up to 4 MeV. Among the key experimental factors which influence the accuracy and precision of a particular type of measurement are the choice of source, detector and scattering geometry. We have examined the interests which motivate the making of

D. A. Bradley; O. D. Goncalves; P. P. Kane

1999-01-01

105

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

Microsoft Academic Search

This paper discusses the latest progress in the development of GRAPE (Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The purpose of GRAPE is to measure the polarization of hard X-rays in the 50-300 keV energy range. We are particularly interested in X-rays that are emitted from solar flares and gamma-ray bursts (GRBs). Accurately measuring the polarization of the emitted

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

2005-01-01

106

X-ray-sensitive device based on a linear CCD for recording the radiation in the energy range 0.20 to 40.00 keV  

Microsoft Academic Search

The C(Pi) M11 x-ray sensitive device is intended for recording the one-dimensional space distribution of x-radiation fluence in the spectral energy range from 0.2 to 40.0 keV and can be used as a part of x-ray spectrometers of different types instead of the photographic film and for measurement of spatial parameters of x-ray beams and oth.

B. F. Voronov; M. V. Emelyanov; Yu. I. Kozhunov; O. B. Kozlov; S. I. Rybin; A. E. Favorski

1999-01-01

107

Measurement of the subthreshold neutron fission cross section of plutonium-240 in the energy range from 10 to 250 keV. [Cross section structure  

Microsoft Academic Search

The subthreshold fission cross section of ²⁴°Pu was measured in the energy range from 10 to 250 keV, using ²³⁵U as a standard. Neutrons were produced via the ⁷Li(p,n) and T(p,n) reaction with the Karlsruhe 3-MV pulsed Van de Graaff accelerator. Fission events were registered by detecting fission neutrons with an NE-213 liquid scintillator with pulse-shape discriminator equipment. The high

K. Wisshak; F. Kaeppeler

1979-01-01

108

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

Microsoft Academic Search

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

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

1988-01-01

109

Transmission and Self-Indication Measurements with U-235 and Pu239 in the 2 eV20 keV Energy Region  

Microsoft Academic Search

The transmission and self-indication measurements with U-235 and Pu-239 have been carried out using the ³He proportional counter and fission chambers in the 2 eV-20 keV energy region. The TOF technique was used with JINR pulse fast reactor IBR-30 in Dubna as a neutron source, the resolution being 100 nsec\\/m (³He counter measurements) and 53 nsec\\/m (fission chamber measurements). The

T. Bakalov; G. Ilchev; S. Toshkov; Tran Khanh Mai; N. Janeva; A. A. van'kov; Yu. V. Grigoriev; V. F. Ukraintsev

1980-01-01

110

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

Microsoft Academic Search

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

Beck

1976-01-01

111

Formation and emission of gold and silver carbide cluster ions in a single C60- surface impact at keV energies: Experiment and calculations  

Microsoft Academic Search

Impact of fullerene ions (C60-) on a metallic surface at keV kinetic energies and under single collision conditions is used as an efficient way for generating gas phase carbide cluster ions of gold and silver, which were rarely explored before. Positively and negatively charged cluster ions, AunCm+ (n = 1-5, 1 <= m <= 12), AgnCm+ (n = 1-7, 1

Y. Cohen; V. Bernshtein; E. Armon; A. Bekkerman; E. Kolodney

2011-01-01

112

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

SciTech Connect

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

Derrien, H

2005-12-05

113

Calculation of H-ranges and H-range stragglings in the energy region 11000 keV  

Microsoft Academic Search

The use of various approximations in calculating proton projected ranges has been studied by the analytical and the Monte Carlo methods. A correction is presented for the projected ranges given in the compilation (Andersen and Ziegler: Hydrogen Stopping Powers and Ranges in All Elements). The greatest correction factors at 1, 10, 100 and 1000 keV are 3.5, 2.1, 1.4 and

A. Luukkainen; M. Hautala

1982-01-01

114

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

NASA Astrophysics Data System (ADS)

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

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

2006-10-01

115

Study of ^2H(d,p)^3H reactions at several ten keV energies by the four-body Faddeev-Yakubovsky equation  

NASA Astrophysics Data System (ADS)

Low energy ^2H(d,p)^3H and ^2H(d,n)^3He reactions are fundamental subjects not only for studies of stellar nucleosynthesis, but also for fusion reactor applications. The differential and integrated cross sections, S-factors, vector and tensor analyzing powers, and some polarization transfer coefficients for the reactions have been measured at incident deuteron energies from several ten to few hundred keV. We analyze these experimental data by solving the four-body Faddeev-Yakubovsky (FY) equation with realistic nuclear interactions and predict the suppression ratio due to polarizations, ?_pol / ?_0, where ?0 is the total cross section for the unpolarized beam and target, and ?_pol is that for the polarized ones. Previously we have reported the FY calculation for the reactions at Ed = 30keV with the PEST potentials, where the data for the differential cross section and the analyzing powers are fairly well reproduced, although with about 20% discrepancies for the cross section magnitude. This time we report the results of the calculations at Ed = 50 - 90 keV.

Uzu, Eizo; Shinsho, Oryu; Makoto, Tanifuji

2001-10-01

116

241Am(n,?) cross section in the neutron energy region between 0.02 eV and 300 keV  

NASA Astrophysics Data System (ADS)

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

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

2008-04-01

117

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

SciTech Connect

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

Friedman, P.G.

1986-11-25

118

Angular dependence of the electronic energy loss of 800-keV He ions along the Si{l_angle}100{r_angle} direction  

SciTech Connect

We present measurements of the stopping power of 800-keV {sup 4}He ions channeled along the Si{l_angle}100{r_angle} axis, as a function of the incidence angle. We compare the experimental results with theoretical calculations by using the impact-parameter-dependent energy loss obtained from the solution of the time-dependent Schr{umlt o}dinger equation through the coupled-channel method. This nonperturbative calculation provides reliable energy-loss results which are in good agreement with the experimental results. {copyright} {ital 1997} {ital The American Physical Society}

dos Santos, J.H.; Grande, P.L.; Behar, M.; Boudinov, H. [Instituto de Fisica da Universidade Federal do Rio Grande do Sul, Avenida Bento Goncalves 9500, 91501-970, Porto Alegre (Brazil); Schiwietz, G. [Bereich F, Hahn-Meitner-Institut Berlin, Glienicker Strasse 100, D-14109 Berlin (Germany)

1997-02-01

119

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

PubMed

Effective atomic numbers' (Z(eff)) effective electron density (N(el)) for human organs and tissues have been computed in the energy region of 1 keV to 100 GeV using WinXCOM. The computed data of Z(eff) and N(el) are tabulated. The computed values are compared with previous results. The computed data of Z(eff)and N(el)for almost all tissues (34 tissues of different human organs) in the given energy range are not available in literature and find application in radiotherapy and dosimetry. PMID:23274818

Manjunatha, H C; Rudraswamy, B

2013-02-01

120

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

NASA Astrophysics Data System (ADS)

We have developed a high-resolution monochromator (HRM) for the measurement of nuclear resonant scattering (NRS) of synchrotron radiation by Te-125 at 35.49 keV using the backscattering of sapphire (9 1 -10 68). HRMs for nuclei with excitation energies less than 30 keV have been successfully developed using high angle diffractions by silicon crystals. Nearly perfect silicon crystal, however, is not suitable for high efficient HRMs at higher energy regions because the symmetry of the crystal structure is high and the Debye-temperature is low. Therefore, we used high quality synthetic sapphire crystal, which has low symmetry of crystal structure and high Debye-temperature. The temperature of the crystal was precisely controlled around 218 K to diffract synchrotron radiation with a Bragg angle of ?/2 - 0.52 mrad. Energy was tuned by changing the crystal temperature under the condition of constant diffraction angle. Energy resolution was measured by detecting nuclear forward scattering by Te-125 in enriched TeO2. The relative energy resolution of 2.110-7 is achieved, that is 7.5 meV in energy bandwidth. This HRM opens studies on element-specific dynamics and electronic state of substances containing Te-125.

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

2007-10-01

121

Inverse mean free path, stopping power CSDA range, and straggling in Ni, Cu, and Au for electrons of energy S or equal 10 keV calculated from a statistical model  

Microsoft Academic Search

A statistical model is described and employed to calculate inverse mean free path, stopping power, and mean square energy loss for electrons of energy from 0.5 eV to 10 keV above the Fermi level in several solids. From these calculations, electron range in the continuous-slowing-down approximation and straggling are evaluated for electron energies from 10 eV to 10 keV. Table

J. C. Ashley; C. J. Tung; R. H. Ritchie; V. E. Anderson

1976-01-01

122

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

NASA Astrophysics Data System (ADS)

The energy and angular distributions of backscattered electrons produced under the impact of 5 keV electrons with thick Al, Ti, Ag, W and Pt targets are measured. The energy range of backscattered electrons is considered between E_{B} = 50 eV and 5000 eV. The angle of incidence ? and take-off angle ? are chosen to have values ? =0 and 10 and ? = 100, 110 and 120 respectively. The measured energy spectra are compared with the available theoretical models for ?=0 and 10. The elastic peak intensity of backscattered electrons is found to be a function of angle of incidence, take-off angle and atomic number of the target material. The considered theories are reasonably in good agreement with experiment for the energy spectra of the backscattered electrons having their reduced energies ? (=E_{B}/E_0) in the range of 0.20 to 1.00.

Yadav, R. K.; Shanker, R.

2007-03-01

123

Energy and angular distributions of backscattered electrons from the collision of 8-keV electrons with a thick tungsten target  

NASA Astrophysics Data System (ADS)

The energy and angular distributions of backscattered electrons produced under impact of 8.0-keV electrons with a thick tungsten target are measured. The energy range of backscattered electrons is considered between 70 and 1700eV . The angle of incidence ? and the takeoff angle ? are chosen to have values ?=0 , 10, and 20 and ?=110 , 120, and 130, respectively. The energy distribution function exhibits two sharp peaks, which are found to appear at 216 and 548eV . They are identified as Auger peaks of tungsten arising due to electron transitions 4d-6s6p and 4s-6s6p , respectively. The measured energy spectra are compared with two different theoretical models. The theoretical predictions are found to yield a good agreement with the experiment in the considered energy range of the backscattered electrons.

Yadav, R. K.; Shanker, R.

2004-11-01

124

Sputtering yields, range and range straggling in Al following Kr+ ions bombardment in the energy range (20 160) keV  

NASA Astrophysics Data System (ADS)

The sputtering of Al metallic films by 84Kr+ ions has been studied over the energy range (20 160) keV. Sputtering yield data have been extracted by means of the Rutherford backscattering technique (RBS) using a 2 MeV beam of 4He+ ions. They have been compared to values derived by Sigmunds linear cascade theory, Yamamuras semi-empirical formula or by Monte Carlo computer simulation using the TRIM code. A fair agreement was observed between the measured sputtering yields and the predicted ones. The depth profiles of the implanted Kr+ ions into Al have also been measured, and then fitted assuming Gaussian shape distributions, which allowed us to extract the projected range, Rp, and the associated range straggling, ?Rp. For the former stopping parameter, a very good agreement is obtained between experiment and the LSS theory predictions while the MC simulation also accounts satisfactorily for the measured data over the whole explored energy range, reflecting an adequate description of the projectile-target interaction by the universal potential of the Thomas Fermi type assumed in the LSS formalism. In contrast, the ?Rp measured data show to be consistent with the predicted values only at E ? 60 keV but lie to 30% above them at lower energies. This discrepancy not caused by the sputtering effect relates to an incomplete evaluation of the range straggling by theory at low bombarding energies.

Mammeri, S.; Ouichaoui, S.; Zemih, R.; Ammi, H.; Abdesselam, M.; Chami, A. C.

2005-10-01

125

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

SciTech Connect

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

Jimenez-Rey, D.; Zurro, B.; McCarthy, K. J.; Baciero, A. [Laboratorio Nacional de Fusion por Confinamiento Magnetico, Asociacion Euratom-CIEMAT, Av. Complutense 22, E-28040, Madrid (Spain); Garcia, G. [Instituto de Matematicas y Fisica Fundamental, Consejo Superior de Investigaciones Cientificas, Serrano 113-bis, 20806, Madrid (Spain)

2008-10-15

126

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

SciTech Connect

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

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

2011-03-15

127

Specification of the plasma environment at geosynchronous orbit in the energy range 87 eV to 288 keV  

SciTech Connect

The particle measurements by the P78-2 SCATHA satellite at near geosynchronous altitudes have been analyzed to obtain average electron and proton fluxes in the energy range 87 eV to 288 keV. The variation of the fluxes about the average values is also reported and the average fluxes are compared to those measured during an intense spacecraft charging event on September 22, 1982. These calculations provide a representation of the plasma environment, which can be used to quantify the surface charging of spacecraft materials in geosynchronous orbit.

Roeder, J.L.

1994-08-15

128

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

Microsoft Academic Search

Mass attenuation coefficients of some boron compounds (H3BO3,Na2B4O7 and B3Al2O3) and the trommel sieve waste (TSW) have been measured by using an extremely narrow collimated-beam transmission method in the energy range 15.74640.930keV. The characteristic K? and K? X-rays of Zr, Mo, Ag, In, Sb, Ba and Pr passed through H3BO3,Na2B4O7, B3Al2O3 and TSW were detected with a high-resolution Si(Li) detector.

Orhan ?elli; Salih Erzeneo?lu; Recep Boncukuo?lu

2003-01-01

129

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

SciTech Connect

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

Gaines, J.L.; Wittmayer, F.J.

1986-06-01

130

Supralinear response of LiF:Mg,Ti (TLD100) after exposure to 100 keV average energy X-rays  

Microsoft Academic Search

The response of LiF:Mg,Ti (TLD-100) induced by 100keV average energy X-rays has been investigated for air kerma values between 10mGy and 1000Gy. Measurements were performed in air, using the NIST M200 beam (200kV operating voltage). The air kerma at the dosimeter surface was measured with a free-air chamber, with combined uncertainty between 0.06% and 0.08% in air kerma rate. A

G. Massillon-JL; O. vila; M. E. Brandan

131

Study of the 36 Cl( n, p ) 36 S reaction in the neutron energy range up to 10 keV  

Microsoft Academic Search

The36Cl(n,p)36S reaction cross-section was measured by the time-of-flight method in the IBR-30 pulsed reactor of the JINR. The measured cross-section shows three not previously observed neutron resonances with energies En = 1.3; 3.5 and 8.2 keV for which the parameters Ap=gGnGp\\/G: 0.07 0.01; 0.08 + 0.03 and 1.7 + 0.3 eV were determined, respectively. Comparison of these results with the

Yu. M. Gledenov; Yu. P. Popov; J. Rigol; V. I. Salatsky

1985-01-01

132

Study of the36Cl( n, p)36S reaction in the neutron energy range up to 10 keV  

Microsoft Academic Search

The36Cl( n,p)36S reaction cross-section was measured by the time-of-flight method in the IBR-30 pulsed reactor of the JINR. The measured cross-section shows three not previously observed neutron resonances with energies En = 1.3; 3.5 and 8.2 keV for which the parameters Ap= gGammanGammap\\/Gamma: 0.07 0.01; 0.08 + 0.03 and 1.7 + 0.3 eV were determined, respectively. Comparison of these results

Yu. M. Gledenov; Yu. P. Popov; J. Rigol; V. I. Salatsky

1985-01-01

133

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

NASA Astrophysics Data System (ADS)

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.

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

2005-10-01

134

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

SciTech Connect

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

Li Zhichao; Guo Liang [Department of Modern Physics and CAS Key Laboratory of Basic Plasma Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Jiang Xiaohua; Liu Shenye; Huang Tianxuan; Yang Jiamin; Li Sanwei; Zhao Xuefeng; Du Huabin; Song Tianming; Yi Rongqing; Liu Yonggang; Jiang Shaoen; Ding Yongkun [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang, Sichuan 621900 (China); Zheng Jian [Department of Modern Physics and CAS Key Laboratory of Basic Plasma Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2010-07-15

135

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

SciTech Connect

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

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

2010-11-12

136

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

137

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

SciTech Connect

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

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

2011-06-01

138

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

SciTech Connect

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

Perez-Calatayud, Jose; Ballester, Facundo; Das, Rupak K.; DeWerd, Larry A.; Ibbott, Geoffrey S.; Meigooni, Ali S.; Ouhib, Zoubir; Rivard, Mark J.; Sloboda, Ron S.; Williamson, Jeffrey F. [Radiotherapy Department, La Fe Polytechnic and University Hospital, Valencia 46026 (Spain); Department of Atomic, Molecular and Nuclear Physics, University of Valencia, Burjassot 46100 (Spain); Department of Human Oncology, University of Wisconsin, Madison, Wisconsin 53792 (United States); Department of Medical Physics and Accredited Dosimetry and Calibration Laboratory, University of Wisconsin, Madison, Wisconsin 53706 (United States); Department of Radiation Physics, University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030 (United States); Department of Radiation Oncology, Comprehensive Cancer Center of Nevada, Las Vegas, Nevada 89169 (United States); Radiation Oncology, Lynn Regional Cancer Center, 16313 South Military Trail, Delray Beach, Florida 33484 (United States); Department of Radiation Oncology, Tufts University School of Medicine, Boston, Massachusetts 02111 (United States); Department of Medical Physics, Cross Cancer Institute, Edmonton, Alberta T6G 1Z2 (Canada); Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298 (United States)

2012-05-15

139

Study of surface activation of PET by low energy (keV) Ni+ and N+ ion implantation  

NASA Astrophysics Data System (ADS)

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 1014 to 1 1016 ions/cm2. 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 (Eg) deduced from absorption spectra; was calculated by Tauc relation. Raman spectroscopy shows quantitatively the chemical nature at the damage caused by the Ni+ and N+ bombardment. The ration of ID/IG 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.

Nathawat, Rashi; Kumar, Anil; Kulshrestha, V.; Vijay, Y. K.; Kobayashi, T.; Kanjilal, D.

2008-11-01

140

Transmission and self-indication measurements with U-235 and Pu-239 in the 2 eV-20 keV energy region  

SciTech Connect

The transmission and self-indication measurements with U-235 and Pu-239 have been carried out using the /sup 3/He proportional counter and fission chambers in the 2 eV-20 keV energy region. The TOF technique was used with JINR pulse fast reactor IBR-30 in Dubna as a neutron source, the resolution being 100 nsec/m (/sup 3/He counter measurements) and 53 nsec/m (fission chamber measurements). The sample thickness was varied from 0.0013 atom/barns to 0.172 atom/barns. Average total cross sections with self shielding factors and self-shielding fission factors were determined for energies within ABBN nuclear constant set.

Bakalov, T. (Joint Inst. for Nuclear Research, Dubna, USSR); Ilchev, G.; Toshkov, S.; Mai, T.K.; Janeva, N.; Van'kov, A.A.; Grigoriev, Yu.V.; Ukraintsev, V.F.

1980-09-01

141

Calculation of the total Rayleigh scattering cross sections of photons in the energy range of 30-50 keV for Nb and Mo elements  

NASA Astrophysics Data System (ADS)

The total Rayleigh scattering cross sections are calculated in the energy range of 30-50 keV using the modified relativistic form factors (MRFF), non-relativistic form factors (NFF), and relativistic form factors (RFF). Numerical calculations are made for energies above the K-threshold comparisons, for medium-Z elements (Nb and Mo), primarily at small momentum transfers. The integration range is divided into intervals using a modified formula to take into account the smaller scattering angles. The calculated cross sections based on MRFF, NFF, and RFF are presented and compared with the tabulated theoretical values. It is found that the values calculated using the NFF and RFF are smaller than the tabulated values with a ratio of 3-7%. It is also observed that the smallest total Rayleigh scattering cross section values are obtained using the MRFF.

Bke, Aysun

2011-05-01

142

Study of the36Cl( n, p)36S reaction in the neutron energy range up to 10 keV  

NASA Astrophysics Data System (ADS)

The36Cl( n,p)36S reaction cross-section was measured by the time-of-flight method in the IBR-30 pulsed reactor of the JINR. The measured cross-section shows three not previously observed neutron resonances with energies En = 1.3; 3.5 and 8.2 keV for which the parameters Ap= g?n?p/?: 0.07 0.01; 0.08 + 0.03 and 1.7 + 0.3 eV were determined, respectively. Comparison of these results with the excited states obtained by the36S( p, ?)37Cl reaction made possible a more exact determination of the scale energy of the37Cl nucleus excited states.

Gledenov, Yu. M.; Popov, Yu. P.; Rigol, J.; Salatsky, V. I.

1985-12-01

143

Mass energy-transfer and mass energy-absorption coefficients, including in-flight positron annihilation for photon energies 1 keV to 100 MeV, 1992  

SciTech Connect

Mass energy-transfer and mass energy-absorption coefficients are tabulated in units of sq cm/g for photon energies between 1 keV and 100 MeV for 29 elements (Z = 1-92), and 14 mixtures and compounds of general dosimetric interest. Cross sections for photo-effect, incoherent scattering, pair and triplet production are those compiled or generated by the National Institute of Standards and Technology (NIST) (formerly the National Bureau of Standards). Corrections are included for in-flight positron annihilation, previously not applied in NIST calculations for energies above 10 MeV. Agreement with recently published data is good for energies above 1 MeV, but the authors find differences in mass energy-absorption coefficients in the low energy region of as much as 4% compared with the last NIST compilation, and as much as 9% when compared with other recent compilations.

Higgins, P.D.; Attix, F.H.; Hubbell, J.H.; Seltzer, S.M.; Berger, M.J.

1992-03-01

144

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

SciTech Connect

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

Jandel, M.; Bredeweg, T. A.; Bond, E. M.; Chadwick, M. B.; Clement, R. R.; Couture, A.; O' Donnell, J. M.; Haight, R. C.; Reifarth, R.; Rundberg, R. S.; Ullmann, J. L.; Vieira, D. J.; Wilhelmy, J. B.; Wouters, J. M. [Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Macri, R. A.; Wu, C. Y.; Becker, J. A. [Lawrence Livermore National Laboratory, Livermore, CA, 94550 (United States)

2008-04-17

145

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

PubMed

Effective atomic numbers for photon energy absorption, Z(PEA,eff), and for photon interaction, Z(PI,eff), have been calculated by a direct method in the photon-energy region from 1 keV to 20 MeV for biological molecules, such as fatty acids (lauric, myristic, palmitic, stearic, oleic, linoleic, linolenic, arachidonic, and arachidic acids), nucleotide bases (adenine, guanine, cytosine, uracil, and thymine), and carbohydrates (glucose, sucrose, raffinose, and starch). The Z(PEA,eff) and Z(PI,eff) values have been found to change with energy and composition of the biological molecules. The energy dependence of the mass attenuation coefficient, Z(PEA,eff), and the mass energy-absorption coefficient, Z(PI,eff), is shown graphically and in tabular form. Significant differences of 17%-38% between Z(PI,eff) and Z(PEA,eff) occur in the energy region 5-100 keV. The reasons for these differences, and for using Z(PEA,eff) rather than Z(PI,eff) in calculations of the absorbed dose, are discussed. PMID:18293593

Manohara, S R; Hanagodimath, S M; Gerward, L

2008-01-01

146

High-energy (100-keV) e-beam lithography applied for fabrication of deep-submicrometer SAW devices on lithium niobate and quartz  

NASA Astrophysics Data System (ADS)

Fabricating submicron feature size Surface Acoustic Wave (SAW) devices on Lithium Niobate and Quartz allows one to take advantage of their unique piezoelectric material properties and operate at higher frequencies. With the recent availability of high performance, high energy e-beam nanowriter tools such as the Leica/Phillips EBPG-HR5 resident at this facility, SAW devices with very narrow line/space transducer gratings can be investigated. Utilizing very high energy (100 keV) direct write electron beam lithography (EBL), allows for processing of deep submicron features with an associated wider process latitude. This is specially desirable when applying EBL to high average Z materials such as lithium niobate. A previously presented paper demonstrated 400 and 500 nm line/space interdigitated transducer fingers on quartz and lithium niobate substrates. E-Beam lithography (30 keV) was used with two and three level, positive and negative tone processes respectively. In this current work a bilevel positive tone process is used by the authors, and involves first spinning a preparation of (1:1) ZEP-320-37 (Nagase Chemical) positive e-beam resist. A commercially available conductive polymer known as TQV-501 (Nitto Chemical) is then spun onto the wafer and serves as a charge removal vehicle. The TQV-501 film is removed by the development procedure. Xylene is used as the developer. Contact pads and interdigitated transducer elements are realized by e-beam metal deposition and lift off process. We will show a direct write positive tone process for the fabrication of deep submicron (400 nM and smaller) interdigitated transducer gratings on Lithium Niobate and Quartz substrates. An improved process dose latitude is seen because of the reduced expected proximity effect at high beam energy.

Kondek, Christine A.; Poli, Louis C.

1995-05-01

147

plutonium isotopic analysis in the 30 KeV to 210 KeV range  

SciTech Connect

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

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

2001-01-01

148

Calibration of X-ray detectors in the 8 to 115 keV energy range and their application to diagnostics on the National Ignition Facility  

SciTech Connect

The calibration of X-ray diagnostics is of paramount importance to the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). National Security Technologies LLC (NSTec) fills this need by providing a wide variety of calibration and diagnostic development services in support of the ongoing research efforts at NIF. The X-ray source in the High Energy X-ray lab utilizes induced fluorescence in a variety of metal foils to produce a beam of characteristic X rays ranging from 8 to 111 keV. Presented are the methods used for calibrating a High Purity Germanium detector, which has been absolutely calibrated using radioactive check sources, compared against a silicon photodiode calibrated at Physikalisch Technische Bundesanstalt (PTB). Also included is a limited presentation of results from the recent calibration of the upgraded Filter Fluorescer X ray Spectrometer.

J. J. Lee, M. J. Haugh, G. LaCaille, and P. Torres

2012-10-01

149

Calibrating of x-ray detectors in the 8 to 111 keV energy range and their application to diagnostics on the National Ignition Facility  

NASA Astrophysics Data System (ADS)

The calibration of X-ray diagnostics is of paramount importance to the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL). National Security Technologies LLC (NSTec) fills this need by providing a wide variety of calibration and diagnostic development services in support of the ongoing research efforts at NIF. The Xray source in the High Energy X-ray lab utilizes induced fluorescence in a variety of metal foils to produce a beam of characteristic X-rays ranging from 8 to 111 keV. Presented are the methods used for calibrating a High Purity Germanium detector, using NIST traceable radioactive sources, and compared against a silicon photodiode calibrated at Physikalisch Technische Bundesanstalt (PTB). A limited presentation of results from the recent calibration of the upgraded Filter Fluorescer X-ray Spectrometer is included.

Lee, Joshua J.; Haugh, Michael J.; LaCaille, Greg; Torres, Peter

2012-10-01

150

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

151

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

SciTech Connect

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

Imazono, T.; Koike, M.; Koeda, M.; Nagano, T.; Sasai, H.; Oue, Y.; Yonezawa, Z.; Kuramoto, S.; Terauchi, M.; Takahashi, H.; Handa, N.; Murano, T. [QuBS, Japan Atomic Energy Agency (JAEA), 8-1-7 Umemidai, Kizugawa, Kyoto 619-0215 (Japan); Device Dept., Shimadzu Corp., 1 Nishinokyo-Kuwabarcho, Nakagyo-ku, Kyoto 604-8511 (Japan); IMRAM, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); EC Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan)

2012-05-17

152

High-precision measurement of the light response of BC-418 plastic scintillator to protons with energies from 100 keV to 10 MeV  

NASA Astrophysics Data System (ADS)

The determination of the light response of many organic scintillators to various types of radiation has been a subject of numerous experimental as well as theoretical studies in the past. But while the data on light response to particles with energies above 1 MeV are precise and abundant, the information on light response to very low energy particles (i.e. below 1 MeV) is scarce or completely missing. In this study we measured the light response of a BC-418 scintillator to protons with energies from 100 keV to 10 MeV. The experiment was performed at Weapons Neutron Research Facility at LANSCE, Los Alamos. The neutron beam from a spallation source is used to irradiate the active target made from BC-418 plastic scintillator. The recoiled protons detected in the active target are measured in coincidence with elastically scattered incident neutrons detected by and adjacent liquid scintillator. Time of flight of the incident neutron and the knowledge of scattering geometry allow for a kinematically complete and high-precision measurement of the light response as a function of the proton energy.

Henzl, Vladimir; Daub, Brian; French, Jennifer; Matthews, June; Kovash, Michael; Wender, Stephen; Famiano, Michael; Koehler, Katrina; Yuly, Mark

2010-11-01

153

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

Microsoft Academic Search

We have determined experimentally optical constants for eight thin film materials that can be used in hard X-ray multilayer coatings. Thin film samples of Ni.97V.03, Mo, W, Pt, C, B4C, Si and SiC were deposited by magnetron sputtering onto superpolished optical flats. Optical constants were determined from fits to reflectance-vs-incidence angle measurements made using synchrotron radiation over the energy range

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

2004-01-01

154

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

SciTech Connect

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.

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

2011-11-15

155

Measurement of D(d,p)T Reaction Cross Sections in Sm Metal in Low Energy Region (10<=Ed<=20 keV)  

NASA Astrophysics Data System (ADS)

To study the screening effect of nuclear reactions in metallic environments, the thick target yields, the cross sections and the experimental S(E) factors of the D(d,p)T reaction have been measured on deuterons implanted in Sm metal at 133.2 K for beam energies ranging from 10 to 20 keV. The thick target yields of protons emitted in the D(d,p)T reaction are measured and compared with those data extrapolated from cross sections and stopping power data at higher energies. The screening potential in Sm metal at 133.2 K is deduced to be 52056 eV. As compared with the value achieved in the gas target, the calculated screening potential values are much larger. This screening potential cannot be simply interpreted only by the electron screening. Energy dependences of the cross section ?(E) and the experimental S(E) factor for D(d,p)T reaction in Sm metal at 133.2 K are obtained, respectively.

Wang, Tie-Shan; Yang, Zhen; Yunemura, H.; Nakagawa, A.; Lv, Hui-Yi; Chen, Jian-Yong; Liu, Sheng-Jin; Kasagi, J.

2007-11-01

156

Differential Scattering of Helium Ions on Targets of He, Ne, and Ar at Energies from 120 to 830 keV  

NASA Astrophysics Data System (ADS)

The scattering of He+ projectiles by impact on the noble gases He, Ne, and Ar was investigated in the energy range 120-830 keV under single-collision conditions. Specifically, the experiment measured, as a function of angle in the range 1 -8, the total differential scattering cross section as well as the differential cross sections for scattering without change of charge, for scattering with charge transfer, and for scattering with electron stripping. The total differential scattering cross section was found to be in agreement with a theoretical differential scattering cross section calculated classically using a screened Coulomb potential. Thus, the scattering of the particles in these close encounters is determined primarily by the mutual nuclear repulsion and may be adequately described by classical mechanics. The fraction of particles in a particular charge state was independent of the scattering angle, a result consistent with theory and with previous experiments at slightly lower energies. For the resonant case He+ + He, it was found that the fraction of scattered particles which had picked up an electron during the collision could be prediced by a semiempirical equation. Good agreement was also found when comparing relative charge-state populations with the predictions of a statistical theory.

Taylor, G. O.; Thomas, E. W.; Martin, D. W.

1970-11-01

157

Efficiency calibration of a HPGe detector in the [46.54-2000] keV energy range for the measurement of environmental samples  

NASA Astrophysics Data System (ADS)

Here we describe a general method of calibrating the efficiency of a Ge /?-ray spectrometer. The method, which is based on the work of Quintana and Fernndez (Appl. Radiat. Isot. 47 /(1996) 911), can now be applied to many different experimental set-ups including both liquid and solid environmental samples. The method requires two different types of experimental inputs. Firstly, it requires measurements with radioactive sources emitting cascades of /? rays covering the energy range of interest. Secondly, it requires measurements with sources emitting isolated /? rays in order to provide coincidence-summing corrections. On this basis, we establish a general function to describe the energy dependence of the efficiency for the particular geometry and source matrix. The method has been applied to 11 different experimental arrangements to provide efficiency calibrations over the range 46.54-2000keV with associated uncertainties ranging from 0.1% to 1.8%. This allows high precision measurements with environmental samples, which often have very low activities.

Daza, M. J.; Quintana, B.; Garca-Talavera, M.; Fernndez, F.

2001-09-01

158

Ion-atom scattering and interatomic potentials for ions of noble metals and period II elements incident on neon and argon with energies in the range 8-25 keV  

Microsoft Academic Search

Information about the potential energy of interaction was obtained for the metal ions, Na+, Mg+, Al+, P+, Cl+, Cu+, Ag+, Au+, Ni+, Zr+, on the inert gases Ar0, Ne0. The scattering of an ion beam in the energy range 8-25 keV, by passage through a gas, was used to measure incomplete total cross sections against energy curves from which the

C. Foster; I. H. Wilson; M. W. Thompson

1972-01-01

159

Absolyutnaya spektral'naya chuvstvitel'nost' fotodiodnykh lineek v rentgenovskom diapazone 7-20 kehV. (Absolute spectral sensitivity of photodiode arrays in the X-ray energy range 7-20 keV).  

National Technical Information Service (NTIS)

The results of the investigation of absolute spectral sensitivity of linear photodiode arrays (the kind LF1024-25/2) as X-ray one-coordinate detectors in the energy range from 7 to 20 keV are presented. The measurements have been carried out with the use ...

I. P. Dolbnya S. G. Kurylo

1991-01-01

160

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

SciTech Connect

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

Andreasson, J.; Iwan, B.; Abreu, E.; Seibert, M. M.; Hajdu, J.; Timneanu, N. [Department of Cell and Molecular Biology, Uppsala University, Box 596, SE-75124 Uppsala (Sweden); Andrejczuk, A. [Faculty of Physics, University of Bialystok, Lipowa Str. 41, PL-15424 Bialystok (Poland); Bergh, M. [Swedish Defence Research Agency, SE-16490 Stockholm (Sweden); Caleman, C. [Physik Department E17, Technische Universitaet Muenchen, James-Franck-Strasse, DE-85748 Garching (Germany); Nelson, A. J. [Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550 (United States); Bajt, S.; Faeustlin, R. R.; Singer, W.; Toleikis, S.; Tschentscher, T. [Deutsches Elektronen-Synchrotron DESY, Notkestrasse 85, DE-22603 Hamburg (Germany); Chalupsky, J.; Hajkova, V.; Juha, L. [Institute of Physics ASCR, Na Slovance 2, CZ-18221 Prague 8 (Czech Republic); Chapman, H. N. [Center for Free-Electron Laser Science, DESY, Notkestrasse 85, DE-22607 Hamburg (Germany); Department of Physics, University of Hamburg, Luruper Chaussee 149, DE-22761 Hamburg (Germany); Heimann, P. A. [Lawrence Berkeley National Laboratory, 1 Cyclotron Road, California 94720 (United States)

2011-01-15

161

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

SciTech Connect

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

Bueyuekuslu, H.; Kaplan, A., E-mail: kaplan@fef.sdu.edu.t [Sueleyman Demirel University, Faculty of Arts and Sciences, Department of Physics (Turkey); Aydin, A. [Kirikkale University, Faculty of Arts and Sciences, Department of Physics (Turkey); Tel, E. [Gazi University, Faculty of Arts and Sciences, Department of Physics (Turkey); Yildirim, G. [Abant Izzet Baysal University, Faculty of Arts and Sciences, Department of Physics (Turkey)

2010-10-15

162

Electron impact calculations of total elastic cross sections over a wide energy range - 0.01 eV to 2 keV for CH4, SiH4 and H2O  

NASA Astrophysics Data System (ADS)

In this paper we report the results of a new theoretical methodology for determining the total elastic electron scattering cross section, Q el , over a wide range of incident energies between 0.01 eV and 2 keV. We have combined results from the UK molecular R-matrix code using Quantemol-N software to determine Q el for incident energies between 0.01 eV and the ionization threshold of the target with calculations based on the spherical complex optical potential formalism for higher energies up to 2 keV. We present results for three selected molecular targets; CH4, SiH4 and H2O as exemplars of the methodology. The present results were found to be in good agreement with previous experimental and theoretical results. The total elastic cross sections for such a wide energy range are reported perhaps for the first time.

Vinodkumar, M.; Limbachiya, C. G.; Joshipura, K. N.; Mason, N. J.

2011-02-01

163

Spin dependence of the ¹⁶⁵Ho total cross section in the neutron-energy region from 4 eV to 100 keV  

Microsoft Academic Search

The method of transmission of polarized neutrons through a polarized target at the IBR-30 pulsed reactor has been used to measure the spin dependence of the total cross section of ¹⁶⁵Ho in the neutron-energy region from 4 eV to 100 keV. Spins are obtained for 55 neutron resonances up to an energy of 310 eV. In the region of the

G. G. Akopyan; V. P. Alfimenkov; Y. Veshbitski; A. I. Ivanenko; Y. D. Mareev; N. I. Moreva; O. N. Ovchinnikov; L. B. Pikelner; E. I. Sharapov

1977-01-01

164

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

SciTech Connect

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

Ipe, Nisy E.

1998-11-17

165

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

SciTech Connect

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

Ipe, Nisy E.

1998-11-17

166

Formation and emission of gold and silver carbide cluster ions in a single C60- surface impact at keV energies: Experiment and calculations  

NASA Astrophysics Data System (ADS)

Impact of fullerene ions (C60-) on a metallic surface at keV kinetic energies and under single collision conditions is used as an efficient way for generating gas phase carbide cluster ions of gold and silver, which were rarely explored before. Positively and negatively charged cluster ions, AunCm+ (n = 1-5, 1 <= m <= 12), AgnCm+ (n = 1-7, 1 <= m <= 7), AunCm- (n = 1-5, 1 <= m <= 10), and AgnCm- (n = 1-3, 1 <= m <= 6), were observed. The Au3C2+ and Ag3C2+ clusters are the most abundant cations in the corresponding mass spectra. Pronounced odd/even intensity alternations were observed for nearly all AunCm+/- and AgnCm+/- series. The time dependence of signal intensity for selected positive ions was measured over a broad range of C60- impact energies and fluxes. A few orders of magnitude immediate signal jump instantaneous with the C60- ion beam opening was observed, followed by a nearly constant plateau. It is concluded that the overall process of the fullerene collision and formation/ejection of the carbidic species can be described as a single impact event where the shattering of the incoming C60- ion into small Cm fragments occurs nearly instantaneously with the (multiple) pickup of metal atoms and resulting emission of the carbide clusters. Density functional theory calculations showed that the most stable configuration of the AunCm+ (n = 1, 2) clusters is a linear carbon chain with one or two terminal gold atoms correspondingly (except for a bent configuration of Au2C+). The calculated AuCm adiabatic ionization energies showed parity alternations in agreement with the measured intensity alternations of the corresponding ions. The Au3C2+ ion possesses a basic Au2C2 acetylide structure with a ?-coordinated third gold atom, forming a ?-complex structure of the type [Au(?-Au2C2)]+. The calculation shows meaningful contributions of direct gold-gold bonding to the overall stability of the Au3C2+ complex.

Cohen, Y.; Bernshtein, V.; Armon, E.; Bekkerman, A.; Kolodney, E.

2011-03-01

167

Formula for the total stopping power from 2 keV to 10 keV for a metal  

NASA Astrophysics Data System (ADS)

On the basis of the range-energy relationship, the relationships ( L 2-10) among the total stopping power from 2 keV to 10 keV for a metal ( S 2-10), the energy exponent ( n 2-10), the primary energy at the surface ( W p0), and the parameter ( A 2-10) were deduced. In addition, the relationships ( L 10-30) among the total stopping power from 10 keV to 30 keV for a metal ( S 10-30), the energy exponent ( n 10-30), W p0 and the parameter ( A 10-30) were obtained. According to some relationships between the parameters of the secondary electron yield from 2 keV to 10 keV for a metal ( ? 2-10), the composition of the secondary electron yield from 10 keV to 30 keV for a metal ( ? 10-30), L 2-10, and L 10-30, the universal formula for expressing S 2-10 as a function of S 10-30, ? 2-10, ? 10-30, the backscattered coefficient ( ?) from 2 keV to 10 keV, ? from 10 keV to 30 keV and W p0 was deduced. The S 2-10 calculated from this universal formula and the S 2-10 measured experimentally were compared, and we conclude that the formula presented in this paper is universal for S 2-10.

Xie, Ai-Gen; Lai, Min; Zhang, Chen-Yi

2013-01-01

168

Implant 9500xR: a high productivity implantation system for 5E10-1E16 ion.cm-2 dose and 5 keV750 keV energy applications  

Microsoft Academic Search

The capability of the Implant 9500xR ion implanter has been extended to become an all purpose implanter. The Implant 9500xR not only has all capability of a high current implanter, but it can also achieve very stable beam currents well below 1 mA (c.f. medium current implanters) for low dose applications. The ion energy range has also been extended to

B. Adibi; P. Edwards

1996-01-01

169

Ratio of Neutron Capture Cross Sections for (super 186)Os and (super 187)Os at 25-keV Neutron Energy.  

National Technical Information Service (NTIS)

The ratio of the neutron capture cross sections for 186Os and 187Os was measured at the 25-keV iron-filtered neutron beam facility of a 10-MW reactor. A value of 0.41 plus or minus 0.04 was obtained. Using this ratio, the age of the universe was determine...

J. C. Browne G. P. Lamaze I. G. Schroeder

1976-01-01

170

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

Microsoft Academic Search

Transmission images and tomographic imaging based scattered radiation is evaluated from biological materials, for example, Polyethylene, Poly carbonate, Plexiglas and Nylon using 10, 15, 20 and 25 keV synchrotron X-rays. The SYRMEP facility at Elettra,Trieste, Italy and the associated detection system has been used for the image acquisition. The scattered radiation is detected for each sample at three energies at

Donepudi V. Rao; Takao Akatsuka; Giuliana Tromba

2004-01-01

171

Comparison of some lead and non-lead based glass systems, standard shielding concretes and commercial window glasses in terms of shielding parameters in the energy region of 1 keV100 GeV: A comparative study  

Microsoft Academic Search

The effective atomic numbers, Zeff of some glass systems with and without Pb have been calculated in the energy region of 1keV100GeV including the K absorption edges of high Z elements present in the glass. Also, these glass systems have been compared with some standard shielding concretes and commercial window glasses in terms of mean free paths and total mass

Murat Kurudirek; Yksel zdemir; nder ?im?ek; Ridvan Durak

2010-01-01

172

Cross Sections and Swarm Coefficients for Nitrogen Ions and Neutrals in N2 and Argon Ions and Neutrals in Ar for Energies from 0.1 eV to 10 keV  

Microsoft Academic Search

Graphical and tabulated data and the associated bibliography are presented for cross sections for elastic, excitation, and ionization collisions of N+, N+2, N, and N2 with N2 and for Ar+ and Ar with Ar for laboratory energies from 0.1 eV to 10 keV. Where appropriate, drift velocities and reaction or excitation coefficients are calculated from the cross sections and recommended

A. V. Phelps

1991-01-01

173

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

Microsoft Academic Search

Two lightweight telescope detector systems, codenamed SLED-1 and SLED-2, with the capability to monitor electron and ion fluxes within an energy range spanning 34 keV to a few tens of MeV, were launched on the twin spacecraft of the Soviet Phobos Mission to Mars and its moons in July 1988. Solar-related particle enhancements recorded during the Cruise Phase, and also

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

1991-01-01

174

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

SciTech Connect

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

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

2010-07-15

175

High spectral resolution Al2O3/B4C, SiC/Si, SiC/B4C, and SiC/C multilayer structures for the photon energies of 6 keV to 19 keV  

NASA Astrophysics Data System (ADS)

A double multilayer monochromator with each multilayer composed of four stripes with different d-spacing providing spectral resolution of 0.3% to 0.8% in the energy range of 6keV to 19keV has been developed. Test multilayer structures with d-spacing from 2.3nm to 10.6nm have been deposited by magnetron sputtering. X-ray characterization has been performed at OSMIC by using a recently upgraded diffractometer setup and Cu-K? radiation and at the APS. The following material combinations were studied before the final choice of materials for the high energy resolution monochromator has been made: Al2O3/B4C, SiC/Si, SiC/B4C and SiC/C. To minimize the effect of internal stress built in multilayer structure on X-ray characteristics flat and thick 1" diameter silicon substrates supplied by Wave Precision Inc. were used for all calibration coatings. Final coatings were deposited on two 145mm long, 60mm wide and 30mm thick silicon substrates. Resolution of SiC/Si structures with d1=2.3nm, N1=1000 and d2=3nm, N2=700 was measured at Cu-K? with X-ray beam divergence of 14 arcsec to be 0.216% and 0.34% respectively. For plane waves the resolution is expected to be 0.13% and 0.19%, respectively.

Platonov, Yuriy Y.; Martynov, Vladimir V.; Kazimirov, Alexander; Lai, Barry

2004-11-01

176

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

NASA Astrophysics Data System (ADS)

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

Khelfaoui, Friha; Lasri, Boumediene; Abbes, Oukacha

2012-06-01

177

Solar Flare 4: 10 keV X-ray Spectrum.  

National Technical Information Service (NTIS)

The 4-10 keV solar flare spectrum includes highly excited lines of stripped Ca, Fe, and Ni ions as well as a continuum steeply falling with energy. Groups of lines at approximately 7 keV and approximately 8 keV, observed during flares by the broad-band RH...

K. J. H. Phillips

2004-01-01

178

Theoretical cross sections for keV antiprotons  

NASA Astrophysics Data System (ADS)

Partial and total close-coupled semiclassical (impact parameter) cross sections and total classical Monte-Carlo cross sections for interactions inbar p + Ps andbar p, p+H collisions are computed in the intermediate keV range for antiprotons,bar p, up to 100 keV lab. Total cross sections for antihydrogen,bar H, formation are found to be large, 10-2010-16 cm2 in a wider energy range than was anticipated earlier, up to some 20 keV lab. New estimates of cross sections for ionisation of atomic hydrogen by antiproton impact are reported for the low-energy range 1 30 keV lab where they are 10-2010-17 cm2, being much larger than the corresponding cross sections for ionisation of hydrogen by proton impact. Data for excitation of H bybar p impact is also presented.

Ermolaev, A. M.

1989-03-01

179

Internal electron conversion of the isomeric {sup 57}Fe nucleus state with an energy of 14.4 keV excited by the radiation of the plasma of a high-power femtosecond laser pulse  

SciTech Connect

We recorded the spectrum of delayed secondary electrons ejected from the target, which was coated with a layer of iron enriched with the {sup 57}Fe isotope to 98%, under its irradiation by fluxes of broadband X-ray radiation and fast electrons from the plasma produced by a femtosecond laser pulse at an intensity of 10{sup 17} W cm{sup -2}. Maxima were identified at energies of 5.6, 7.2, and 13.6 keV in the spectrum obtained for a delay of 90 - 120 ns. The two last-listed maxima owe their origin to the internal electron conversion of the isomeric level with an energy of 14.4 keV and a lifetime of 98 ns to the K and L shells of atomic iron, respectively; the first-named level arises from a cascade K - L{sub 2}L{sub 3} Auger process. Photoexcitaion by the X-ray plasma radiation is shown to be the principal channel of the isomeric level excitation. (interaction of laser radiation with matter)

Golovin, G V; Savel'ev-Trofimov, Andrei B; Uryupina, D S; Volkov, Roman V [International Laser Center, M. V. Lomonosov Moscow State University, Moscow (Russian Federation)

2011-03-31

180

Microstructure and biocompatibility investigation of biomaterial alumina after 30keV and 60keV nitrogen ion implantation  

Microsoft Academic Search

Polycrystalline alumina is widely used as biomaterial. It is being used as hip joints, tooth roots etc. Commercially available polycrystalline alumina samples were implanted with 30keV and 60keV energy N+ ions at different ion doses ranging from 51015ions\\/cm2 to 51017ions\\/cm2. Change in surface structure is studied using optical microscope. Compound formation at the surface of alumina is confirmed with GXRD.

Deep Shikha; Usha Jha; S. K. Sinha; P. K. Barhai; K. G. M. Nair; S. Dash; A. K. Tyagi; S. Kalavathy; D. C. Kothari

2009-01-01

181

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

NASA Astrophysics Data System (ADS)

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

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

2004-05-01

182

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

SciTech Connect

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

Rao, Donepudi V. [Synchrotron Radiation for Medical Physics, Elettra, Trieste (Italy); Akatsuka, Takao [Dept of Bio-System Engineering, Faculty of Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan); Tromba, Giuliana [Department of Physics, Sir. C.R.R. Autonomous College, Eluru-534007., W.G. Dt., A. P. (India)

2004-05-12

183

X-ray Shielding of an Ionizer using Low-Energy X-rays below 9.5 keV for Ultra-Clean Assembly Line of Electronic Devices  

NASA Astrophysics Data System (ADS)

An ionizer has been developed using a low-energy X-ray for producing ion pairs that are transported by clean air through a shielding plate to objects to be discharged. The shielding plate should shield the X-ray of below 9.5 keV, while it should pass sufficient amount of the ion pairs. In this study, characteristics of the structural condition of the shielding plate has been investigated, on both the shielding effect and the ability to pass the ion pairs. We confirmed the structural condition that the leakage dose rate of the low-energy X-rays could be decreased to less than 1 ?Sv/h while allowing the passage of enough ion pairs to eliminate the static electricity.

Suzuki, Masanori; Sato, Tomokatsu; Matsuhashi, Hideaki; Mizuno, Akira

2005-07-01

184

Experimental measurements of K X-ray production cross-sections and yields for the elements with 58 ?slant Z ?slant 64 at 123.6 keV photon energy  

NASA Astrophysics Data System (ADS)

Considering the importance of the K X-ray production cross-sections (?_{Ki}^x) as well as the K shell fluorescence yields (?K) for the determination of element concentrations in a given material, we have measured them experimentally for the elements Ce, Pr, Nd, Sm, Eu and Gd using photons at 123.6 keV from a 57Co radioisotope source. Furthermore, the K X-rays intensity ratios (K?/K?) for these elements have been investigated. The characteristic K X-rays emitted by the target were detected by a high-resolution with an energy resolution of 160 eV full with at half-maximum ( FWHM) at 5.96 keV. The experimental results of K X-ray production cross-sections were compared with theoretically predicted values based on relativistic Hartree-Slater and Hartree-Fock theories. Similarly, the measured K shell fluorescence yields/cross-sections and the K X-rays intensity ratios were compared with the theoretical values. In most cases, there is an agreement between the experimental and theoretical data within the experimental uncertainties.

Ertu?ral, B.

2007-08-01

185

The dissociation of 13CH and 12CH2 molecules in He and N2 at beam energies of 80-250 keV and possible implications for radiocarbon mass spectrometry  

NASA Astrophysics Data System (ADS)

Isotopic ratios of 14C at natural levels can be efficiently measured with accelerator mass spectrometry (AMS). In compact AMS systems, 13CH and 12CH2 molecular interferences are destroyed in collisions with the stripper gas, a process which can be described by dissociation cross sections. These dissociation cross sections determine the gas areal density required for sufficient attenuation of the interfering molecular beams, and are therefore key parameters in the effort to further reduce the terminal voltage and thus the size of the AMS system. We measured the dissociation cross sections of 13CH and 12CH2 in N2 and He in the energy range of 80-250 keV. In N2, cross sections were constant for energies above 100 keV with average values per molecule of (8.1 0.4) 10-16 cm2 for 13CH and (9.5 0.5) 10-16 cm2 for 12CH2. In He, cross sections were constant over the full measured range of 80-150 keV with average values of (4.2 0.3) 10- 16 cm2 and (4.8 0.4) 10-16 cm2, respectively. A considerable reduction of the terminal voltage from the currently used 200 kV while using N2 for 13CH and 12CH2 molecule dissociation is not possible: the required N2 areal densities of 1.4 ?g/cm2, consequential angular straggling and a decreasing 1+ charge state fraction would reduce the ion beam transmission too much. This is not the case for He: sufficient molecule dissociation can be obtained with gas densities of 0.4 ?g/cm2, for which angular straggling is relatively small. In addition, the 1+ charge state fraction still increases at lower stripping energies. Thus, the usage of He for stripping and molecule dissociation might allow the development of even smaller 14C-AMS systems than available today.

Schulze-Knig, T.; Seiler, M.; Suter, M.; Wacker, L.; Synal, H.-A.

2011-01-01

186

(Temperature coefficient of U-235 fueled thermal reactors and nuclear data on eta at thermal neutron energies and 239-Pu fission cross sections between 1 and 100 keV)  

SciTech Connect

The Evaluation Cooperation Subgroup, Actinide Data in the Thermal Energy Range,'' met primarily to discuss problems related to the temperature coefficient of U-235 fueled thermal reactors and nuclear data on eta at thermal neutron energies, the number of neutrons emitted per neutron absorbed. The preliminary results of the eta measurements done by M. Moxon of Harwell at Oak Ridge were presented and preliminary results by H. Weigman of Geel with a new method were presented. All three measurements from Geel show a pronounced down-slope of eta with decreasing neutron energy and both measurements by Moxon show only a very slight down slope. Acceptance of the Geel results would solve about one-third of the problem in the calculated reactor temperature coefficient. The Evaluation Cooperation Subgroup, 239-Pu Fission Cross Sections between 1 and 100 keV,'' met to discuss the 4% lower than the previously evaluated fission cross sections between 20 eV and 100 keV as evaluated from the fission data of the Weston and Todd and transmission data of J. A. Harvey (all of ORNL). These lower fission cross sections are discrepant with integral measurements, however, it is conceivable that there could be compensating effects, perhaps in the U-238 cross sections. A general meeting and a benchmark testing session of the JEF were attended as a representative of CSEWG JEF-2.2 is scheduled for general release after about another year of testing. Cooperation in evaluation of nuclear data between Europe, Japan, and the US has increased dramatically in the last few years because of manpower limitations.

Weston, L.W.

1990-12-21

187

Inverse mean free path, stopping power, csda range, and straggling in polystyrene for electrons of energy < or = 10 keV. Interim technical report  

Microsoft Academic Search

The interaction of electrons with solid polystyrene, -(C⁸H⁸)-, is described, based on a model insulator theory to account for the response of the valence electrons, and carbon K-shell ionization cross sections derived from atomic, generalized oscillator strengths. Contributions to the inverse mean free path and energy loss due to these two excitation processes are tabulated for incident electrons with energies

J. C. Ashley; C. J. Tung; R. H. Ritchie; V. E. Anderson

1978-01-01

188

M-shell X-ray production cross-sections for elements with 67 {<=} Z {<=} 92 at incident photon energies E{sub M{sub 1}}keV  

SciTech Connect

The X-ray production cross-sections for the Mk (k = {xi}, {delta}, {alpha}, {beta}, {zeta}, {gamma}, m{sub 1} and m{sub 2}) groups of X-rays have been evaluated for all the elements with 67 {<=} Z {<=} 92 at incident photon energies ranging E{sub M{sub 1}}keV using currently available theoretical data sets of different physical parameters, namely, partial photoionization cross-sections, X-ray emission rates, fluorescence and Coster-Kronig yields, and the K-shell/L{sub j} (j = 1-3) subshell to the M{sub i} (i = 1-5) subshell vacancy transfer probabilities, based on the independent particle models.

Chauhan, Yogeshwar; Kumar, Anil [University College of Engineering, Punjabi University, Patiala 147002, Punjab (India); Puri, Sanjiv [University College of Engineering, Punjabi University, Patiala 147002, Punjab (India)], E-mail: sanjivpurichd@yahoo.com

2009-07-15

189

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

SciTech Connect

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

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

2010-01-01

190

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

Microsoft Academic Search

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

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

1990-01-01

191

Assessment of the ''thermal normalization technique'' for measurement of neutron cross sections vs energy. [Above 20 keV, resonance, fission integrals, error minimization  

Microsoft Academic Search

Refined knowledge of the thermal neutron cross sections of the fissile nuclides and of the (n,..cap alpha..) reaction standards, together with the reasonably well known energy dependence of the latter, have permitted resonance-region and low-keV fissile nuclide cross sections to be based on these standards together with count-rate ratios observed as a function of energy using a pulsed ''white'' source.

R. W. Peelle; G. de Sassure

1977-01-01

192

Seeded quantum FEL at 478 keV  

SciTech Connect

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

Guenther, M. M.; Jentschel, M.; Thirolf, P. G.; Seggebrock, T.; Habs, D. [Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany); Institut Laue-Langevin, F-38042 Grenoble (Germany); Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching (Germany); Ludwig-Maximilians-Universitaet Muenchen, D-85748 Garching, Germany and Max-Planck-Institut fuer Quantenoptik, D-85748 Garching (Germany)

2012-07-09

193

Absolute detection efficiency of a micro-channel plate detector to x-rays in the 1--100 KeV energy range.  

National Technical Information Service (NTIS)

There is little information in the literature on the performance of working micro-channel plate (MCP) detectors at high x-ray energies. We have measured the absolute efficiency of a microchannel-plate-intensified, subnanosecond, one dimensional imaging x-...

G. A. Burginyon B. A. Jacoby J. K. Wobser R. D. Ernst D. S. Ancheta

1992-01-01

194

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

Microsoft Academic Search

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

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

2011-01-01

195

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

SciTech Connect

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

Kostroun, V.O.

1992-07-05

196

Analysis of metal alloys by Rayleigh to Compton ratios and X-ray fluorescence peaks in the 50 to 122 keV energy range  

Microsoft Academic Search

A method for nondestructive analysis of metal alloys able to explore inner strata of material up to >= 100 mum is described. The method employs two or more low-energy gamma-ray radioactive sources in a backscattering geometry (Theta = 135). The ratio R\\/C between elastic (R) and inelastic (C) scattered components together with the ratio I\\/C between the X-ray fluorescence intensity

G. E. Gigante; L. J. Pedraza; S. Sciuti

1985-01-01

197

Inverse mean free path, stopping power, CSDA range, and straggling in Ge and GaAs for electrons of energy 10 keV  

Microsoft Academic Search

The interaction of electrons with the solids Ge and GaAs is described, based on a model insulator theory for the valence band electrons and inner shell ionization derived from classical-binary-collision cross sections. Contributions to the inverse mean free path and stopping power from the various interaction processes are tabulated for electron energies from threshold, approximately 2 eV for Ge and

J. C. Ashley; C. J. Tung; R. H. Ritchie; V. E. Anderson

1976-01-01

198

On the existence of low-energy photons (<150 keV) in the unflattened x-ray beam from an ordinary radiotherapeutic target in a medical linear accelerator  

NASA Astrophysics Data System (ADS)

Low-energy photons (<150 keV) are essential for obtaining high quality x-ray radiographs. These photons are usually produced in the accelerator target, but are effectively absorbed by the flattening filter and, at least partially, by the target itself. Experimental proof is presented for the existence of low-energy photons in the unflattened x-ray beam produced by a 6 MeV electron beam normally incident on the thinner of the two existing ports of the all-Cu radiotherapeutic target of a Clinac 18 (Varian Associates) linear accelerator. A number of one-shot absorption measurements were carried out with 12 foils of Pb absorbers with thicknesses varying from 0.25 to 3 mm in steps of 0.25 mm arranged symmetrically around the central axis on a 7.2 cm radius circumference. A Kodak ECL film-screen-cassette combination was used as a detector in the absorption measurements, in which optical density was measured as a function of the thickness of the Pb absorbers. Two sets of absorption measurements were carried out: the first one with the Clinac 18 6 MV unflattened beam and the second one with the Clinac 600C 6 MV therapeutic counterpart beam. There is a striking difference between the two sets: the optical density versus Pb-absorber thickness curve shows a sharp increase in optical density at small absorber thicknesses in the case of the unflattened 6 MV x-ray beam as compared with a gently sloping dependence in the case of the 6 MV therapeutic beam. A semi-quantitative assessment of the low-energy photon contribution to the whole optical density/contrast is presented. A 0.85 mm thick Pb absorber intercepting the 6 MV unflattened x-ray beam eliminates almost totally the sharp peak in the optical density curve at small Pb-absorber thicknesses. This constitutes additional evidence for the existence of low-energy photons (<150 keV) in the unflattened 6 MV beam from the Cu therapeutic target.

Tsechanski, A.; Krutman, Y.; Faermann, S.

2005-12-01

199

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

Microsoft Academic Search

This paper discusses the latest progress in the development of GRAPE\\u000a(Gamma-Ray Polarimeter Experiment), a hard X-ray Compton Polarimeter. The\\u000apurpose of GRAPE is to measure the polarization of hard X-rays in the 50-300\\u000akeV energy range. We are particularly interested in X-rays that are emitted\\u000afrom solar flares and gamma-ray bursts (GRBs). Accurately measuring the\\u000apolarization of the emitted

J. S. Legerea; P. Bloser; J. R. Macri; M. L. McConnella; T. Narita; J. M. Ryan

2005-01-01

200

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

PubMed

The laser integration line (LIL) located at CEA-CESTA is equipped with x-ray plasma diagnostics using different kinds of x-ray components such as filters, mirrors, crystals, detectors, and cameras. The CEA-DAM of Arpajon is currently developing x-ray calibration methods and carrying out absolute calibration of LIL x-ray photodetectors. To guarantee LIL measurements, detectors such as x-ray cameras must be regularly calibrated close to the facility. A new x-ray facility is currently available to perform these absolute x-ray calibrations. This paper presents the x-ray tube based high energy x-ray source delivering x-ray energies ranging from 0.9 to 10 keV by means of an anode barrel. The purpose of this source is mainly to calibrate LIL x-ray cameras but it can also be used to measure x-ray filter transmission of plasma diagnostics. Different x-ray absolute calibrations such as x-ray streak and framing camera yields, x-ray charge-coupled device quantum efficiencies, and x-ray filter transmissions are presented in this paper. A x-ray flat photocathode detector sensitivity calibration recently performed for a CEA Z-pinch facility is also presented. PMID:20515133

Hubert, S; Dubois, J L; Gontier, D; Lidove, G; Reverdin, C; Soulli, G; Stemmler, P; Villette, B

2010-05-01

201

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

SciTech Connect

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

Hubert, S.; Dubois, J. L. [Commissariat a l'Energie Atomique, DAM, CESTA, BP 2, Le Barp 33114 (France); Gontier, D.; Lidove, G.; Reverdin, C.; Soullie, G.; Stemmler, P.; Villette, B. [Commissariat a l'Energie Atomique, DAM, DIF, Arpajon F-91290 (France)

2010-05-15

202

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

NASA Astrophysics Data System (ADS)

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

Hubert, S.; Dubois, J. L.; Gontier, D.; Lidove, G.; Reverdin, C.; Soulli, G.; Stemmler, P.; Villette, B.

2010-05-01

203

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

NASA Astrophysics Data System (ADS)

Diffractive optical elements (DOE) are becoming important as optical signal processing elements in increasingly diverse applications. These elements, fabricated on quartz, may be used as phase shift type masks or as embedded components that implement a transfer function within a processing network. A process is under development for the fabrication of a DOE implementing a Jervis error diffusion kernel for research in half tone image processing. Dry etching is performed after lithography and pattern transfer through a nickel mask. This results in etched areal features on the substrate. An optical diffraction medium is thus created. Lithographic patterning is done by e-beam lithography (EBL) to realize small features, but also offers the important advantage of a large depth of field which relaxes the problem of complex surface topology. The recent availability of high energy (100 KeV) lithography tools provides a capability for precision overlay, small feature resolution, and enhanced image contrast through a lower induced proximity effect. Patterning by EBL on insulating substrates is complicated by the necessity of providing a vehicle for the avoidance of charge buildup on the surface. In a previously presented paper a methodology was shown for the use of TQV-501 (Nitto Chemical) antistatic compound as a final spin on film for use with PMMA and SAL-601 (Shipley). In this current work, a process is described using EBL and a high performance positive resist working with a final film layer of antistatic TQV-501 on a nickel coated wafer. The process may then be reapplied to realize additional lithographic levels in registration, for multilevel DOE components. High energy (100 KeV) EBL is used to provide high quality pattern definition. The e-beam sensitive resist, ZEP-320-37 (Nagase Chemical) in dilution, together with a top film layer of TQV-501 serves as a bilevel resist system and is used for patterning the desired image before definition of the nickel mask through a wet etch. ZEP- 320-37 in 1:1 dilution with the native solvent is spin applied and softbaked for 2 hours at 120 degree(s)C, after which the antistatic film is spin applied and softbaked for 10 minutes at 70 degree(s)C. After exposure, the TQV film is removed within the development procedure itself. The image is developed in xylene followed by a thorough IPA rinse. The pattern is then transferred to the nickel film via a dilute HCl etch bath. Finally, magnetron RIE is performed on the substrate through the defined nickel mask, after which the nickel film is completely removed in HCl.

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

1995-06-01

204

Neutron-capture gamma rays below 40 keV  

NASA Astrophysics Data System (ADS)

A review of neutron-capture gamma ray measurements below 40 keV is given and experimental methods are discussed. New experiments with a Si(Li) detector have been performed. Energies and absolute intensities of low energy (n, ?) transitions in 28Al, 40K, 52V, 128I, 134Cs, 160Tb, 166Ho, 170Tm, 176Lu, 182Ta, 192Ir, 198Au and 233Th are presented. These new results can serve calibration purposes and provide nuclear structure information.

Durner, P.; von Egidy, T.; Hartmann, F. J.

1989-06-01

205

Stopping powers of 2003000 keV 4He and 5501750 keV 1H ions in Vyns  

Microsoft Academic Search

Stopping powers for Vyns (vinylchloride-vinylacetate copolymer) were measured both for 4He ions in the range 2003000 keV and for 1H ions in the range 5501750 keV using the transmission technique. A detector model is used for the energy calibration to improve the accuracy of the stopping power curve for 4He ions in the low energy region. The estimated uncertainty in

F. Munnik; A. J. M. Plompen; J. Risnen; U. Wtjen

1996-01-01

206

Stopping powers and extrapolated ranges for electrons (1-10 keV) in metals  

Microsoft Academic Search

A thin film quasiadiabatic calorimeter has been applied to the measurement of the stopping power for electrons, under conditions of small angle scattering, in Al, Ni, Cu, Ag and Au in the energy region 1 keV to 10 keV. Results are presented with an estimated precision of 15%. Corrections are included for the multiple scattering enhancement of the apparent path

K O Al-Ahmad; D E Watt

1983-01-01

207

Bremsstrahlung energy spectra from electrons of kinetic energy 1 keV less than or equal to T less than or equal to 2000 keV incident on neutral atoms 1 less than or equal to Z less than or equal to 92  

SciTech Connect

A tabulation is presented of theoretical predictions for the electron bremsstrahlung energy spectrum from neutral atoms as a function of atomic number Z, incident electron kinetic energy T, and fraction of energy radiated k/T (k is the emitted photon energy). Tabulated values for 2 less than or equal to Z less than or equal to 92 are obtained by interpolation from a smaller set of calculated data points. These calculated points were obtained by describing bremsstrahlung as a single-electron transition in a relativistic self-consistent screened potential. Tabulated values for Z = 1 are obtained from the formfactor corrected Born approximation times the Elwert Factor. The tables correct errors found in a previous tabulation. Various plots of the tabulation are presented and the general behavior of the energy spectrum is discussed. Energy scaling of the spectrum is investigated and T/Z is found to best scale the data.

Kissel, L.; MacCallum, C.; Pratt, R.H.

1981-08-01

208

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

SciTech Connect

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

Ackermann, M.; Bechtol, K.; Berenji, B.; Blandford, R. D.; Bloom, E. D.; Borgland, A. W.; Bouvier, A. [W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States); Asano, K. [Interactive Research Center of Science, Tokyo Institute of Technology, Meguro City, Tokyo 152-8551 (Japan); Atwood, W. B. [Santa Cruz Institute for Particle Physics, Department of Physics and Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95064 (United States); Axelsson, M. [Department of Astronomy, Stockholm University, SE-106 91 Stockholm (Sweden); Baldini, L.; Bellazzini, R.; Bregeon, J. [Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy); Ballet, J. [Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France); Barbiellini, G. [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy); Baring, M. G. [Department of Physics and Astronomy, Rice University, MS-108, P.O. Box 1892, Houston, TX 77251 (United States); Bastieri, D. [Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy); Bhat, P. N. [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Bissaldi, E. [Max-Planck Institut fuer extraterrestrische Physik, 85748 Garching (Germany); Bonamente, E., E-mail: jchiang@slac.stanford.ed, E-mail: sylvain.guiriec@lpta.in2p3.f, E-mail: j.granot@herts.ac.u, E-mail: ohno@astro.isas.jaxa.j [Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)

2010-06-20

209

Backside-thinned CCDs for keV electron detection  

NASA Astrophysics Data System (ADS)

This paper presents preliminary results on the performance of n-channel, backside-thinned charge-coupled devices (CCDs) as electron-bombarded-semiconductor (EBS) imagers for the detection of 1-10 keV electrons. The devices exhibit average EBS gains ranging from approximately 50 at 1 keV to >1600 at 10 keV. Device radiation tolerance has been investigated by exposing normally-clocked devices to 6 keV electron doses up to 0.01 Coulombs/cm(superscript 2). Room temperature pre- and post-irradiation results are presented for these key device parameters: full well capacity, dark current, and charge transfer efficiency (CTE). At the maximum dose of 0.01 Coulombs/cm(superscript 2), full well capacity decreases 9% from an initial value of 680,000 e(superscript -), and dark current increases from energies other than 6 keV is estimated by measurement of the x-ray generation efficiency of silicon as a function of electron energy. Device stability after temperature cycling has been studied by subjecting packaged devices to vacuum bakes of 24 hours at 300 degree(s)C. Full well, CTE, EBS gain, and output amplifier performance are unchanged after the extended temperature cycle, while dark current decreases slightly by 15%. In summary, these initial results indicate that the CCD can function as both an efficient and robust electron imager.

Ravel, Mihir K.; Reinheimer, Alice L.

1991-07-01

210

Search For Anomalous n-p Scattering At 60 eV-140 keV  

SciTech Connect

A search for an anomalous n-p scattering from a polyethylene sample (CH{sub 2}) at 8 final energies between 64 eV and 2.5 keV was carried out. The scattering intensities were compared to that from a graphite (C) sample. The results were found to confirm our previous n-p results on H{sub 2}O at a final energy of 24.3 keV where no n-p scattering anomaly was observed. The present results refute all proposed models attempting to explain the occurrence of any n-p scattering anomaly at keV neutron energies.

Moreh, R. [Physics Department, Ben-Gurion University of the Negev, Beer-Sheva 84120 (Israel); Block, R. C.; Danon, Y. [Gaerttner LINAC Laboratory, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)

2009-01-28

211

Gel behavior of keV ion irradiated polystyrene  

Microsoft Academic Search

Among the chemical and physical modifications induced by ion bombardment of polymers, the solubility changes are very important because of technological application for lithography in microelectronic devices. Solubility changes due to the occurrence of crosslinkings have been followed on monodisperse and polydisperse polystyrene after ion irradiations (10111014 ions\\/cm2, keV energy). By using the Inokuty gel theory [M. Inokuti J. Appl.

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

1988-01-01

212

Interdiffusion in polystyrene crosslinked by keV ion irradiation  

Microsoft Academic Search

Mass transport properties of polymers are deeply influenced by the presence of crosslinks between chains, induced by high-energy ion irradiation. Diffusion coefficients in polystyrene, measured after irradiation with 300-keV protons in the fluence range 10121014 ions\\/cm2, show strong variation up to two orders of magnitude. Diffusion process has been studied in deuterated\\/hydrogenated polystyrene bilayer by using the forward recoil analysis

L. Calcagno; G. Foti

1992-01-01

213

Collisional Excitation of N+ at 50 keV  

Microsoft Academic Search

The excitation spectrum of N+ has been observed by examining the energy lost by a 50- keV N+ beam passing through a He target. The spectrum exhibits dramatic features with large cross sections. Determination of the approximate ratio of metastable to ground-state ions in the primary ion beam has permitted measurement of excitation cross sections from both ground-state and metastable

D. H. Crandall; G. York; V. Pol; J. T. Park

1972-01-01

214

Detection of 10-20 keV H+, He+ ions and electrons by planar oxide passivated and ion implanted silicon diodes  

NASA Astrophysics Data System (ADS)

A low noise UV-enhanced silicon photodiode has been modified into a low energy particle detector by removing the antireflection oxide layer. The electronic noise of a 100 mm2 device and a conventional charge sensitive preamplifier has been measured to 2.3 keV FWHM at room temperature operation. The response of this detector to low energy particles has been investigated. Electrons with 10 keV initial energy looses 0.8 keV in the surface deadlayer. Further, the sum of the energy losses in the deadlayer and to nuclear collisions have been measured to about 3.8 keV for 10 keV protons and 5.4 keV protons and 5.4 keV for 12 keV He+ ions

Johansen, G. A.; Stadsnes, J.; Sraas, F.; Hansen, T. E.

1991-11-01

215

Capability of the ASTRO-E Hard X-ray Detector for high-energy transients and ?-ray Bursts  

NASA Astrophysics Data System (ADS)

The Hard X-Ray Detector (HXD) is one of the instruments on board ASTRO-E, scheduled for lanch in January-February 2000. The HXD consists of 16 Well-type phoswich counters, surrounded by 20 active shield counters (Anti Coincidence Counters: Anti-Counters). It covers the energy range 10-600 keV with a very low background. Because the Anti-Counters are made of thich high-Z material with a very large geometrical area, they retain a large effective area up to high energies. Therefore the Anti-Counters can be used for monitoring high-energy transient sources and ?-ray bursts. In this paper, the all sky monitoring function with the Anti-Counters and the result of their ground calibration tests are described. .

Terada, Y.; Yamaoka, K.; Kokubun, M.; Kotoku, J.; Mizuno, T.; Kataoka, J.; Takahasi, T.; Murakami, T.; Makishima, K.; Kamae, T.; HXD Team

2000-04-01

216

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

NASA Astrophysics Data System (ADS)

Depth graded multilayer designs for hard x-ray telescopes in the 10 keV to 70-80 keV energy range have had either W or Pt as the heavy element. These materials have been chosen because of reasonable optical constants, the possibility to grow smooth interfaces with the spacer material, and the stability over time. On the flip side both W and Pt have an absorption edge -- 69.5 keV (W) and 78.4 keV (Pt) -- which is very close to the two 44Ti lines at 67.9 keV and 78.4 keV that are produced in the envelope of a super nova explosion. Other materials have better optical constants and no absorption edges in this energy range, for example Ni0.93V0.07, but are not used because of high interface roughness. By using a WC/SiC multilayer for the bottom and a Ni0.93V0.07/SiC multilayer for the thicker top layers of a depth graded multilayer we have made a reflector that doesn't have a clear absorption edge. This reflector has been measured at energies between 8 keV and 130 keV. At a graze angle of 0.11 degree there is still nearly the same reflectivity below the W absorption edge as for a traditional W based coating, and above the W absorption edge there is still 48% reflection at 80 keV.

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

2007-09-01

217

Incoherent scattering functions of iron, copper, zirconium, tin, tantalum, tungsten, gold and lead, in the momentum range 2 -1 ? q ? 46 -1 at 661.6 keV photon energy  

NASA Astrophysics Data System (ADS)

The incoherent scattering functions were calculated from the measured differential incoherent scattering cross sections for 661.6 keV photons with a hyper pure germanium detector in the angular range of 5 120 covering the momentum range 2 -1 ? q ? 46 -1 for iron, copper, zirconium, tin, tantalum, tungsten, gold and lead. The measured incoherent scattering functions were compared with the NRHF values, recent DHFR values and other measured values.

Krishnaveni, S.; Gowda, Ramakrishna

2005-04-01

218

Angular distribution of particles sputtered from Cu, Pt and Ge targets by keV Ar+ ion bombardment  

Microsoft Academic Search

Measurements of angular distributions of material sputtered from polycrystalline copper and platinum and amorphous germanium targets by irradiation with argon ions are reported. The beam energy was varied from 1.25 keV to 320 keV (for Cu and Pt upwards from 10 keV only). All targets yielded an angular distribution more outward peaked than the cosine predicted by collision-cascade theory. The

Hans Henrik Andersen; Bjarne Stenum; Tom Srensen; Harry J. Whitlow

1985-01-01

219

Origin of 30-100 keV protons observed in the upstream region of the earth's bow shock  

Microsoft Academic Search

A Fermi-type acceleration model is constructed to explain the origin of energetic protons (30-100 keV) which have been observed upstream of the bow shock. It is shown that the suprathermal protons (with energy of several keV) can be accelerated up to several tens of keV through the Fermi-type process in which the reflection at the shock front and the scattering

T. Terasawa

1979-01-01

220

G-Factors of the 264 KeV and 632 KeV States in exp 77 As.  

National Technical Information Service (NTIS)

The integral perturbed angular correlation technique has been used to measure the g-factors of the 264 keV and 632 keV nuclear levels in exp 77 As. The g-factor of the 264 keV (5/2 exp - ) state with tau = 450+-30 ps was determined through the 367-264 keV...

F. C. Zawislak J. Schaf J. M. Gualda R. N. Saxena R. P. Livi

1978-01-01

221

Heliospheric neutral atom spectra between 0.01 and 6 keV from IBEX  

NASA Astrophysics Data System (ADS)

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 ~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 ~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-1.

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

2012-07-01

222

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

Microsoft Academic Search

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

David L. Windt; Soizik Donguy; Charles J. Hailey; Jason Koglin; Veijo Honkimaki; Eric Ziegler; Finn E. Christensen; C. M. Hubert Chen; Fiona A. Harrison; William W. Craig

2003-01-01

223

W \\/SiC X-Ray Multilayers Optimized for Use Above 100 KeV  

Microsoft Academic Search

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,

David L. Windt; Soizik Donguy; Charles J. Hailey; Jason Koglin; Veijo Honkimaki; Eric Ziegler; Finn E. Christensen; Hubert Chen; Fiona A. Harrison; William W. Craig

2003-01-01

224

30- to 100keV Protons Upstream From the Earths Bow Shock  

Microsoft Academic Search

Protons of 30 to 100 keV are found upstream from the bow shock whenever interplanetary magnetic fields connect the spacecraft and bow shock. Their energy spectrum is closely power law, d J\\/dE o: E- with v usually close to 3. The spectrum is sharply cut off above 100 keV. The protons do not appear upstream of a boundary determined by

R. P. Lin; C.-I. Meng; K. A. Anderson

1974-01-01

225

A search for the level at 803 keV in 51Cr  

Microsoft Academic Search

The 803 keV level found in 51Cr through the 50Cr(d, p)51Cr reaction does not seem to be generated in the 51V(p, n)51Cr reaction to an intensity greater than 2% of the 747 keV level as determined by observing the direct gamma radiations with a lithium-drifted germanium detector with incident protons of energy in the range 2.310-3.100 MeV.

K. V. K. Iyengar; B. Lal; S. K. Gupta; M. D. Deshpande

1967-01-01

226

Solar wind ions accelerated to 40 keV by shock wave disturbances  

Microsoft Academic Search

Observations in the solar wind with the LASL\\/MPI fast plasma experiment on ISEE 1 and 2 reveal the common presence of ions with energies extending from approx.100 eV up to at least 40 keV in a broad region, typically approx.10⁷ km wide, following interplanetary shocks. Peak differential fluxes up to approx.5 x 10³ (cm² s sr keV)⁻¹ at 28 keV

J. T. Gosling; J. R. Asbridge; S. J. Bame; W. C. Feldman; G. Paschmann; N. Sckopke

1980-01-01

227

Electron fluxes over the polar cap. I. Intense keV fluxes during poststorm quieting  

Microsoft Academic Search

Intense fluxes of keV electrons were observed over large regions of the north polar cap during two periods of magnetospheric quieting following large storms. These fluxes were distinctly field aligned, had energy spectra peaked at both approx. 100 eV and approx. 2 keV, and were not observed in the conjugate hemisphere. A search for similar fluxes in the interplanetary medium

J. D. Foster; J. R. Burrows

1976-01-01

228

Some early results of the keV plasma experiment on GEOS1  

Microsoft Academic Search

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

H. Borg; L.-A. Holmgren; B. Hultqvist; F. Cambou; H. Reme; A. Bahnsen; G. Kremser

1978-01-01

229

Angular Distribution of Particles Sputtered from Cu, Pt and Ge Targets by KeV Ar exp + Ion Bombardment.  

National Technical Information Service (NTIS)

Measurements of angular distributions of material sputtered from polycrystalline copper and platinum and amorphous germanium targets by irradiation with argon ions are reported. The beam energy was varied from 1.25 keV to 320 keV (for Cu and Pt upwards fr...

H. H. Andersen B. Stenum T. Soerensen H. J. Whitlow

1984-01-01

230

Positron Mean Free Paths Between 50eV and 40KeV  

SciTech Connect

We have developed a formalism for calculating the inelastic mean free paths (IMFP's) of positrons by extending an existing semiempirical method developed by Tanuma, Powell, and Penn that is currently used for electrons. As examples, we have calculated the positron IMFP's in the 50 eV to 40 keV energy range for four different elements. In the intermediate-energy region, roughly 200 eV to 2 keV, the inelastic mean free paths for both positrons and electrons are similar. However, at lower energies, differences in correlation and exchange between the leptons during inelastic scattering events result in the inelastic mean free path being smaller for the positrons than for the electrons. At the highest energies, above about 2 keV, the relativistic correction suggested by Inokuti to the scattering cross section has been made. The resulting relativistic inelastic mean free paths are reasonable upper limits for both leptons below the bremsstrahlung regime.

Farrell, Helen Honora; Denison, A. B.

2004-03-01

231

In Situ Thin Film Measurement by X-Rays Induced by 10 KeV-100 KeV Ion Beams.  

National Technical Information Service (NTIS)

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 ...

L. Torrisi L. Calcagno A. Trovato G. Foti

1982-01-01

232

In vivo activation analysis of spinal calcium using 25 keV neutrons  

SciTech Connect

The applicability of 25 keV neutrons to the in vivo activation analysis of spinal calcium is examined both theoretically and experimentally. It is shown that the use of this energy results in an increase in sensitivity over higher energy neutrons so that patient dose may be significantly reduced.

Cousins, T.; Kennett, T.J.; Prestwich, W.V.; Webber, C.E.

1980-11-01

233

Electron transfer in collisions of keV potassium ions with methane molecules  

NASA Astrophysics Data System (ADS)

Absolute total electron transfer cross sections have been measured for the K+-CH4 system, at impact energies 0.5-3.5 keV. The charge transfer cross sections show a monotonic increasing behaviour as a function of the incident energy. Semiempirical calculation is in good agreement with the present cross-section data.

Alarcn, F. B.; Martnez, H.

2013-03-01

234

Solar energetic photon transients (50 keV?100 MeV)  

Microsoft Academic Search

Understanding the origin of transient emissions of energetic photons associated with solar flares and other cosmic sources is a key problem in high energy astrophysics. These impulsive photon emissions span the energy range from a few keV to ?100 MeV and in some cases the temporal and spectral characteristics of solar and cosmic transients are similar. In this review, we

E. L. Chupp

1982-01-01

235

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

SciTech Connect

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

Limbachiya, Chetan [P. S. Science College, Kadi 382 715, Gujarat (India); Vinodkumar, Minaxi [V. P. and R. P. T. P. Science College, Vallabh Vidyanagar 388 120, Gujarat (India); Mason, Nigel [Department of Physics and Astronomy, Open University, Milton Keynes, MK7 6AA (United Kingdom)

2011-04-15

236

Tomographic scanning microscope for 1-4 KeV x-rays  

SciTech Connect

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

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

1995-12-31

237

Response of 100% internal quantum efficiency silicon photodiodes to 200 eV40 keV electrons  

Microsoft Academic Search

Electron irradiation of 100% internal quantum efficiency silicon photodiodes having a thin (60 ) SiO2 dead layer results in measured responsivities ranging from 0.056 A\\/W at an incident electron energy E0=0.2 keV to 0.24 A\\/W at E0=40 keV. By comparing the data to a Monte Carlo simulation of electron interactions with the photodiode over an energy range of 1-40 keV,

H. O. Funsten; D. M. Suszcynsky; S. M. Ritzau; R. Korde

1997-01-01

238

A Study of 2-20 Kev X-Rays from the Cygnus Region.  

National Technical Information Service (NTIS)

Two rocket-borne proportional counters, each with 650 sqen1 c, met area and 1.8 x 7.1 deg FWHM rectangular mechanical collimation, surveyed the Cygnus region in the 2 to 20 keV energy range on two occasions. X-ray spectral data gathered on 21 September 19...

R. D. Bleach

1972-01-01

239

Moessbauer Spectroscopy at the 93.3 KeV gamma Transition at Zn-67.  

National Technical Information Service (NTIS)

This work presents the result of a Moessbauer effect study at the zinc-67 isotope. The 93.3 KeV gamma transition has the highest energy resolution of all accessible Moessbauer transitions. Source and absorber we cooled down to 4.2 K. The aim of the examin...

A. Forster

1981-01-01

240

Interstellar photoelectric absorption cross sections, 0.03-10 keV  

Microsoft Academic Search

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

R. Morrison; D. McCammon

1983-01-01

241

3H(p-->,?)4He reaction below Ep=80 keV  

NASA Astrophysics Data System (ADS)

The 3H(p-->,?)4He reaction was studied at incident energies of Ep=40 and 80 keV at the Triangle Universities Nuclear Laboratory (TUNL) using beams from a polarized ion source. The present study was the logical progression of a previous study of the 2H(p-->,?)3He reaction done by the radiative capture group at TUNL. The angular distributions of the cross section, ?(?), and the analyzing power, Ay(?), were measured at incident proton beam energies of 40 keV and 80 keV. In both cases the beam was stopped in the target. The magnetic dipole transition strength was determined from the results of a TME analysis. A comparison of the M1 strength with that seen in similar reactions in the three-nucleon case made it possible to infer the meson-exchange current origin of most of this strength. Previous measurements of the absolute cross section extended down to beam energies of 100 keV. The present study extends the measured cross section data to lower energies and is consistent with the previous results. A parametrization of the astrophysical S factor including both data sets was performed.

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

2002-04-01

242

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

SciTech Connect

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

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

2009-12-03

243

Scintillation efficiency and ionization yield of liquid xenon for monoenergetic nuclear recoils down to 4 keV  

SciTech Connect

Liquid xenon (LXe) is an excellent material for experiments designed to detect dark matter in the form of weakly interacting massive particles (WIMPs). A low energy detection threshold is essential for a sensitive WIMP search. The understanding of the relative scintillation efficiency (L{sub eff}) and ionization yield of low energy nuclear recoils in LXe is limited for energies below 10 keV. In this article, we present new measurements that extend the energy down to 4 keV, finding that L{sub eff} decreases with decreasing energy. We also measure the quenching of scintillation efficiency caused by the electric field in LXe, finding no significant field dependence.

Manzur, A.; Curioni, A.; Kastens, L.; McKinsey, D. N.; Ni, K.; Wongjirad, T. [Department of Physics, Yale University, New Haven, Connecticut 06520 (United States)

2010-02-15

244

Characteristics of 80 keV positive ion source for Large Helical Device  

SciTech Connect

An additional beamline, BL5, equipped with four positive ion sources will be installed on Large Helical Device (LHD) in 2010. The performance of an ion source which generates 80 keV deuterium and 60 keV hydrogen beams was investigated. The structure of the ion source is based on that of a BL4 ion source on LHD. The main differences between the ion sources for the BL4 and BL5 are the acceleration voltages and the materials of plasma electrodes: copper and molybdenum, respectively. The molybdenum plasma electrode for BL5 has better performance than the copper plasma electrode of BL4. The integrated performance of the ion source for BL5 reached a value equivalent to {approx}58 A in the beam current of hydrogen positive ion at 60 keV in the beam energy.

Nakano, H.; Osakabe, M.; Tsumori, K.; Sato, M.; Shibuya, M.; Ikeda, K.; Nagaoka, K.; Kaneko, O.; Asano, E.; Kondo, T.; Komada, S.; Takeiri, Y. [National Institute for Fusion Science, National Institutes of National Sciences, 322-6 Oroshi-cho, Toki 509-5292 (Japan)

2010-02-15

245

Proposal For A High Reflectivity Laue Lens Tuned On The 511 keV Emission Line  

NASA Astrophysics Data System (ADS)

Study of the 511-keV emission line resulting from the electron-positron annihilation would be precious to search for the location of positron sources in our Galaxy. For this aim, we propose to use Ge crystals bent by grooves to concentrate the 511-keV photons with very high reflectivity. By including the absorption through the crystal, reflectivity has been calculated to be 85% for 3 mm-thick Ge crystal. The energy passband would be a water-bag distribution, as determined by the curvature of crystal. If such a distribution is tuned across the 511 keV line, very high signal-to-noise detection of such radiation is foreseen.

Neri, I.; Guidi, V.; Bagli, E.; Bellucci, V.; Camattari, R.

2011-09-01

246

International key comparison of 24 keV neutron fluence measurements (19932009): CCRI(III)-K1  

Microsoft Academic Search

A comparison of 24.5 keV neutron fluence standards was organized by Section III (Neutron Measurements) of the Comit Consultatif des Rayonnements Ionisants, (CCRI). The exercise involved the circulation of a set of three different-diameter Bonner spheres for calibration in fields with energies around 24.5 keV. The fields were produced using four different methods of neutron production.The responses (counts per unit

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

2010-01-01

247

New measurement of the relative scintillation efficiency of xenon nuclear recoils below 10 keV  

SciTech Connect

Liquid xenon is an important detection medium in direct dark matter experiments, which search for low-energy nuclear recoils produced by the elastic scattering of WIMPs with quarks. The two existing measurements of the relative scintillation efficiency of nuclear recoils below 20 keV lead to inconsistent extrapolations at lower energies. This results in a different energy scale and thus sensitivity reach of liquid xenon dark matter detectors. We report a new measurement of the relative scintillation efficiency below 10 keV performed with a liquid xenon scintillation detector, optimized for maximum light collection. Greater than 95% of the interior surface of this detector was instrumented with photomultiplier tubes, giving a scintillation yield of 19.6 photoelectrons/keV electron equivalent for 122-keV {gamma} rays. We find that the relative scintillation efficiency for nuclear recoils of 5 keV is 0.14, staying constant around this value up to 10 keV. For higher energy recoils we measure a value of 0.21, consistent with previously reported data. In light of this new measurement, the XENON10 experiment's upper limits on spin-independent WIMP-nucleon cross section, which were calculated assuming a constant 0.19 relative scintillation efficiency, change from 8.8x10{sup -44} cm{sup 2} to 9.9x10{sup -44} cm{sup 2} for WIMPs of mass 100 GeV/c{sup 2}, and from 4.5x10{sup -44} cm{sup 2} to 5.6x10{sup -44} cm{sup 2} for WIMPs of mass 30 GeV/c{sup 2}.

Aprile, E.; Choi, B.; Giboni, K. L.; Lim, K.; Monzani, M. E.; Plante, G.; Santorelli, R.; Yamashita, M. [Department of Physics, Columbia University, New York, New York 10027 (United States); Baudis, L. [Physik-Institut, Universitaet Zuerich, CH-8057 Zuerich (Switzerland); Manalaysay, A. [Physik-Institut, Universitaet Zuerich, CH-8057 Zuerich (Switzerland); Department of Physics, University of Florida, Gainesville, Florida 32611 (United States)

2009-04-15

248

Xenon-neon gas proportional-scintillation counters for X rays below 2 keV: experimental results  

Microsoft Academic Search

The energy spectra of X-rays with energies below 2 keV measured with standard Xe filled gas proportional scintillation counters at atmospheric pressure exhibit a distorted tail towards the low energy region, due to the loss of electrons to the detector entrance window. In this framework, a Monte Carlo simulation study taking into account these losses has previously investigated the use

F. I. G. M. Borges; F. P. Santos; J. M. F. dos Santos; T. H. V. T. Dias; P. J. B. M. Rachinhas; C. A. N. Conde

2002-01-01

249

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

Microsoft Academic Search

We present new phenomenological optical model potentials (OMPs) for neutrons and protons with incident energies from 1 keV up to 200MeV, for (near-)spherical nuclides in the mass range 24?A?209. They are based on a smooth, unique functional form for the energy dependence of the potential depths, and on physically constrained geometry parameters. For the first time, this enables one to

A. J. Koning; J. P. Delaroche

2003-01-01

250

Observations of the cosmic X-ray background below 4 keV  

SciTech Connect

The author reports the first measurement of the intensity and spectrum of the diffuse x-ray background in the 0.16 - 3.5 keV band which is free from contamination by sources with fluxes greater than {approximately}4 {times} 10{sup {minus}14} erg cm{sup {minus}2}s{sup {minus}1}. This result was made possible by the development of a number of techniques for removing cosmic-ray contamination and instrumental artifacts in the data collected by the Einstein Observatory Imaging Proportional Counter. The intensity is dependent on galactic longitude even when only high galactic latitude data are used, allowing a lower limit to be set on the galactic contribution to the emission in this band. The spectrum of the total background is consistent with a power law of slope {approximately}0.7 between 0.5 keV and 3.5 keV with a steep rise toward lower energies. A thorough reanalysis of the Einstein Observatory Deep Survey data is presented in order to determine the contribution of detected, discrete sources of x-ray emission to the cosmic x-ray background. Finally, all-sky maps are presented of diffuse x-ray emission in nine energy bands between 0.16 and 3.5 keV utilizing a complete data base of Einstein IPC observations.

Wu, Xiaoyi.

1990-01-01

251

STEREO/IMPACT Observations of Foreshock Electrons from 10 eV-100 keV  

NASA Astrophysics Data System (ADS)

Solar wind electrons are accelerated and reflected back upstream by the terrestrial bow shock into a region known as the electron foreshock. Observed spectra at low energies are consistent with a fast Fermi process, which is dependent on the conservation of the adiabatic moment of the accelerated electrons. In the early part of its mission, the STEREO spacecraft observed many examples of electron beams in the terrestrial foreshock. The combined capabilities of the SWEA and STE instruments on STEREO can measure the electron foreshock spectrum from 10 eV to 100 keV. The highest observed accelerated electron energies can reach up to several tens of keV. These energies are of particular interest because electrons at keV energies and higher have Larmor radii of tens of km or greater, comparable to the scale sizes of the shock. Therefore, the adiabatic condition no longer applies. We compare the observed STEREO foreshock electron energy spectra with predictions based on a Liouville mapping of the observed upstream spectra through a shock interaction, and discuss implications for the fast Fermi theory.

Pulupa, M.; Bale, S.; Lin, R. P.; Larson, D. E.

2010-12-01

252

The Pitch-Angle Distribution Width Between 100 eV to 500 keV During the Solar Electron Burst of 2002 March 22  

NASA Astrophysics Data System (ADS)

A compilation of various spacecraft measurements made over the last 30 years suggests that the pitch-angle distribution (PAD) width of a solar electron burst may have a complex, non-monotonic energy signature. However, only a few studies have considered the PAD width over a broad energy range during a single solar electron burst. Here we use WIND/3DP data to examine the energy dependence of the PAD width between 100 eV to 500 keV during the solar electron burst of 2002 March 22. We find that the PAD width-energy profile during this event was quite dynamic, occasionally showing significant changes in the width-energy profile over a time span of only 15 min. There were times, early on in the burst, when the PAD width below 10 keV was independent of energy. At later times, the PAD width below 10 keV displayed a local maximum at 46 keV. This local maximum was also present before and after the burst, but usually at lower energies. Such a local maximum may be a signature of the electrostatic electron/electron instability [Gary and Saito, GRL 34, 2007; Saito and Gary, JGR 113, 2008]. The PAD width-energy profile above 10 keV also showed considerable variability. There were times when the width increased monotonically with energy above 10 keV, consistent with cyclotron-resonant scattering by turbulence in the inertial range. At other times, the width increased with energy up to approximately 4060 keV and then became independent of energy. At yet other times, the width-energy profile displayed a maximum near 100 keV. These results imply that the details and effectiveness of the wave-particle scattering mechanism vary with energy.

de Koning, C. A.; Gosling, J. T.; Skoug, R. M.; Steinberg, J. T.; Wang, L.; Lin, R. P.

2009-12-01

253

Implications of the 17 keV neutrino  

SciTech Connect

Constraints on the theoretical interpretation of the 17 keV neutrino are reviewed. A simple understanding of the 17 keV neutrino is provided by flavon models, which involve the spontaneous breaking of Abelian lepton symmetries and have only the usual three light neutrino species. Signatures for this class of models include neutrino oscillations, tau decay to an electron and a flavon, and invisible decay modes of the Higgs boson to two flavons.

Hall, L.J.

1991-06-01

254

25keV neutron beam facility at NBS  

Microsoft Academic Search

An iron-filtered, neutron-beam facility that provides a well collimated source of 25-keV neutrons has been developed at the National Bureau of Standards (NBS) Reactor. For selected physics experiments and monoenergetic calibration of neutron dosimeters, the beam flux may be tailored to provide 5 x 10⁵n.cm⁻².s⁻¹ with 99 percent 25-keV neutrons. For other experiments, such as calibration of fast-neutron spectrometers, fluxes

E. D. McGarry; I. G. Schroder

1975-01-01

255

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

NASA Astrophysics Data System (ADS)

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

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

2006-06-01

256

Phase-contrast imaging and tomography at 60 keV using a conventional x-ray tube  

NASA Astrophysics Data System (ADS)

Phase-contrast imaging using grating interferometers has been developed over the last few years for x-ray energies of up to 28 keV. We have now developed a grating interferometer for phase-contrast imaging that operates at 60 keV x-ray energy. Here, we show first phase-contrast projection and CT images recorded with this interferometer using an x-ray tube source operated at 100 kV acceleration voltage. By comparison of the CT data with theoretical values, we find that our measured phase images represent the refractive index decrement at 60 keV in good agreement with the theoretically expected values. The extension of phase-contrast imaging to this significantly higher x-ray energy opens up many new applications of the technique in industry, medicine, and research.

Donath, T.; Pfeiffer, F.; Bunk, O.; Groot, W.; Bednarzik, M.; Grnzweig, C.; Hempel, E.; Popescu, S.; Hoheisel, M.; David, C.

2008-09-01

257

Majority-logic NE-110 detector for keV neutrons  

SciTech Connect

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

Hill, N.W.; Harvey, J.A.; Horen, D.J.; Morgan, G.L.; Winters, R.R.

1984-01-01

258

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

SciTech Connect

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

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

2009-03-10

259

5 keV to 2 MeV lithium implantation and diffusion in amorphous silicon  

Microsoft Academic Search

Low dose implanted lithium depth profiles in preamorphized silicon have been measured in the energy range of 5 keV to 2 MeV by means of three different nuclear reaction techniques and SIMS measurements, and they are compared to theory. Though the agreement is good for the mean projected range, we find systematic deviations for the range straggling.Further, the shapes of

D. Fink; J. P. Biersack; H. P. Schoelch; M. Weiser; S. Kalbitzer; M. Behar; J. P. De Souza; F. C. Zawislak; A. M. Mazzone; H. Kranz

1989-01-01

260

Inelastic scattering of 80 keV electrons in amorphous carbon  

Microsoft Academic Search

The cross-section for inelastic scattering of 80 keV electrons in thin films of evaporated carbon has been measured as a function of energy loss (from 10 to 600 eV) and scattering angle (up to 01 rad). The onergy-loss spectrum shows a broad peak around 24 eV, believed to arise mainly from plasmon oscillation of valence electrons. Losses between 50 and

R. F. Egerton

1975-01-01

261

Monte Carlo Simulation of 1 eV 35 keV Electron Scattering in Teflon  

Microsoft Academic Search

A simple physical model of ≈1 eV 35 keV electron scattering in insulating polymers was proposed. A new correction to Slater's exchange potential was used for the description of low-energy elastic electron scattering. The simulation of electron trajectories was performed using the Monte Carlo technique. The integral and differential characteristics such as the total secondary electron yield and elastic and

Alexandre Palov; Haruhisa Fujii; Sanju Hiro

1998-01-01

262

The emission and propagation of ? 40keV solar flare electrons  

Microsoft Academic Search

Observations of prompt ~ 40 keV solar flare electron events by the IMP series of satellites in the period August, 1966 to December, 1967 are tabulated along with prompt energetic solar proton events in the period 19641967. The interrelationship of the various types of energetic particle emission by the sun, including relativistic energy electrons reported by Cline and McDonald (1968)

R. P. Lin

1970-01-01

263

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

Microsoft Academic Search

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

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

2003-01-01

264

A Compound Refractive Lens for 175 keV X-rays  

Microsoft Academic Search

This is to report on the second step in constructing Compound Refractive Lens for focusing 175 keV X-rays for Magnetic Compton Scattering experiment at the BL08W beamline in SPring-8. The lens consists of the metallic plates with small parabolic grooves pressed into it. The first lens for this high energy was made of Fe. Recently we have performed a test

Andrzej Andrejczuk; Yoshiharu Sakurai; Masayoshi Itou

2007-01-01

265

2keV filtered beam facility at the NBS reactor  

Microsoft Academic Search

A scandium filter that views a manganese scatterer has been installed in a through tube of the National Bureau of Standards Reactor (NBSR). The use of a resonant scatterer eliminates unwanted core neutrons and core gamma rays. This produces a pure 2-keV neutron beam with only 3 percent higher energy neutron contamination and a 1 mR\\/hr⁻¹ gamma-ray background. This should

I. G. Schroder; R. B. Schwartz; E. D. McGarry

1975-01-01

266

Interaction of keV photons with matter and new applications  

Microsoft Academic Search

The fundamental interactions of keV photons with matter, i.e. photoelectric effect and coherent and incoherent scattering are treated from a non-traditional point of view. Section 1 is designed to lay a foundation of the basic science. Section 2 deals with non-imaging analytical techniques that have been developed over the past 20 or so years. These techniques include energy-dispersive X-ray fluorescence,

R. Cesareo; A. L. Hanson; G. E. Gigante; L. J. Pedraza; S. Q. G. Mathaboally

1992-01-01

267

Production of 75keV, 70-A, 10-s ion beams  

Microsoft Academic Search

High-power long pulse ion sources were fabricated and tested at a prototype injector unit for JT-60. Ion beams of 70 A at an energy of 75 keV were extracted repeatedly for up to 10 s. The heat loadings to each grid were within our design values and each grid turned out to be thermally stable during 10 s pulse. The

Masato Akiba; Masanori Araki; Hiroshi Horiike; Takao Ito; Mikito Kawai; Masaaki Kuriyama; Shigeru Kitamura; Shinzaburo Matsuda; Mamoru Matsuoka; Hidetoshi Mukaida; Yoshiaki Oguchi; Yoshihiro Ohara; Tokumichi Ohga; Hiroshi Ohtsuki; Yoshikazu Okumura; Takemasa Shibata; Hirofumi Shirakata; Shigeru Tanaka

1982-01-01

268

CCD imaging from 20 eV to 8 keV  

Microsoft Academic Search

Pulsed x-ray diagnostics operating in the kilovolt and sub-kilovolt regimes are required in the study of x-ray laser schemes. Sensitivity and dynamic range measurements are presented for position-sensitive detector systems, designed and optimized for these spectral regions. Both systems employ cooled, multi-pinned phase CCD's for image capture. For photon energies from 20 eV to 1 keV (where direct detection with

A. G. Macphee; C. L. S. Lewis

1995-01-01

269

CCD imaging from 20 eV to 8 keV  

Microsoft Academic Search

Pulsed x-ray diagnostics operating in the kilovolt and sub-kilovolt regimes are required in the study of x-ray laser schemes. Sensitivity and dynamic range measurements are presented for position-sensitive detector systems, designed and optimized for these spectral regions. Both systems employ cooled, multi-pinned phase CCDs for image capture. For photon energies from 20 eV to 1 keV (where direct detection with

A. G. MacPhee; C. L. S. Lewis

1995-01-01

270

Strain determination and microstructural characterization of 50 keV Sn-ion-implanted Si(001)  

Microsoft Academic Search

Si(001) structures, implanted with Sn at energy of 50 keV and with doses in the range 2-9 x 10(exp 15)\\/sq cm, were investigated by multicrystal x-ray diffraction, reciprocal space mapping (RSM), high-resolution transmission electron microscopy, and secondary-ion-mass spectrometry (SIMS). For Sn doses up to 3.30 x 10(exp 15)\\/sq cm, annealing at 600 C for 30 min under dry N2 atmosphere

M. R. Sardela Jr.; R. Turan; M. Willander; G. V. Hansson; L. Hultman

1995-01-01

271

Backscattering of 8 28 keV electrons from a thick tungsten target  

NASA Astrophysics Data System (ADS)

The backscattering process of 8-28 keV electrons from a thick tungsten target is studied. Measurements on the variation of the backscattering coefficient, eegr, with angle of incidence agr and with diffusion range xd for different impact energies are presented and discussed. Simple analytical expressions based on continuous energy-loss and diffusion of incident electrons inside the target are used to examine the above variations. Over the entire ranges of impact energy and angle of incidence of the present studies, the predictions of the analytical relations are found to be in good agreement with most of our data and with those of earlier workers within experimental errors of measurement.

Yadav, R. K.; Srivastava, Argala; Mondal, S.; Shanker, R.

2003-10-01

272

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

NASA Astrophysics Data System (ADS)

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

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

2005-12-01

273

CONTRIBUTION OF UNRESOLVED POINT SOURCES TO THE DIFFUSE X-RAY BACKGROUND BELOW 1 keV  

SciTech Connect

We present here the analysis of X-ray point sources detected in several observations available in the XMM-Newton public archive. We focused, in particular, on energies below 1 keV, which are of particular relevance to the understanding of the diffuse X-ray background (DXB). The average field of all the exposures is 0.09 deg{sup -2}. We reached an average flux sensitivity of 5.8 x 10{sup -16}ergs{sup -1}cm{sup -2} in the soft band (0.5-2.0 keV) and 2.5 x 10{sup -16}ergs{sup -1}cm{sup -2} in the very soft band (0.4-0.6 keV). In this paper, we discuss the log N-log S results, the contribution to the integrated X-ray sky flux, and the properties of the cumulative spectrum from all sources. In particular, we found an excess flux at around 0.5 keV in the composite spectrum of faint sources. The excess seems to be a general property of all the fields observed suggesting an additional class of weak sources is contributing to the X-ray emission at these energies. Combining our results with previous investigations, we have also quantified the contribution of the individual components of the DXB in the 3/4 keV band.

Gupta, A.; Galeazzi, M. [Physics Department, University of Miami, Coral Gables, FL 33124 (United States)], E-mail: galeazzi@physics.miami.edu

2009-09-01

274

PITCH-ANGLE DISTRIBUTIONS AND TEMPORAL VARIATIONS OF 0.3-300 keV SOLAR IMPULSIVE ELECTRON EVENTS  

SciTech Connect

We investigate the propagation of {approx}0.3-300 keV electrons in five solar impulsive electron events, observed by the WIND three-dimensional Plasma and Energetic Particle instrument, that have rapid-rise and rapid-decay temporal profiles. In two events, the temporal profiles above 25 keV show a second peak of inward-traveling electrons tens of minutes after the first peak, followed by a third peak due to outward-traveling electrons minutes later-likely due to reflection/scattering first at {approx}0.7-1.7 AU past the Earth, and then in the inner heliosphere inside 1 AU. In the five events, below a transition energy E{sub 0} ({approx}10-40 keV), the pitch-angle distributions are highly anisotropic with a pitch-angle width at half-maximum (PAHM) of <15{sup 0} (unresolved) through the time of the peak; the ratio {Lambda} of the peak flux of scattered (22.{sup 0}5-90{sup 0} relative to the outward direction) to field-aligned scatter-free (0{sup 0}-22.{sup 0}5) electrons is {approx}<0.1. Above E{sub 0}, the PAHM at the flux peak increases with energy up to 85{sup 0} at 300 keV, and {Lambda} also increases with energy up to {approx}0.8 at 300 keV. Thus, low-energy electrons propagated essentially scatter-free through the interplanetary medium, while high-energy electrons experienced pitch-angle scattering, with scattering strength increasing with energy. The transition energy E{sub 0} between the two populations is always such that the electron gyroradius ({rho}{sub e}) is approximately equal to the local thermal proton gyroradius ({rho}{sub Tp}), suggesting that the higher energy electrons were scattered by resonance with turbulent fluctuations at scale {approx}>{rho}{sub Tp} in the solar wind.

Wang, L.; Lin, R. P.; Krucker, Saem, E-mail: wanglh@berkeley.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

2011-02-01

275

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

NASA Astrophysics Data System (ADS)

We present a high-brightness 24-keV electron-impact microfocus x-ray source based on continuous operation of a heated liquid-indium/gallium-jet anode. The 30-70 W electron beam is magnetically focused onto the jet, producing a circular 7-13 ?m full width half maximum x-ray spot. The measured spectral brightness at the 24.2 keV In K? line is 3 109 photons/(s mm2 mrad2 0.1% BW) at 30 W electron-beam power. The high photon energy compared to existing liquid-metal-jet sources increases the penetration depth and allows imaging of thicker samples. The applicability of the source in the biomedical field is demonstrated by high-resolution imaging of a mammography phantom and a phase-contrast angiography phantom.

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

2011-12-01

276

Impulsive 2-10 keV solar electron events not associated with flares  

NASA Astrophysics Data System (ADS)

Data from the ISEE 3 satellite reveal a class of impulsive solar electron events with no measurable increase in flux above 10-20 keV. The flux histories and angular distributions indicate that the electrons propagate through interplanetary space with little or no scattering. The smooth extension of the power-law energy spectra down to the limit of the observations at 2 keV indicates that the electrons are accelerated at altitudes greater than 0.5 solar radii in the solar corona. Although these events occur more frequently than any other type of impulsive solar particle event observed, no correlation is found with flares or flare-related activity. However, there is a close correlation with low-frequency type III radio bursts.

Potter, D. W.; Lin, R. P.; Anderson, K. A.

1980-03-01

277

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

SciTech Connect

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

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

2011-12-15

278

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

PubMed

We investigated the fabrication of dense, high aspect ratio hydrogen silsesquioxane (HSQ) nanostructures by 100 keV electron beam lithography. The samples were developed using a high contrast developer and supercritically dried in carbon dioxide. Dense gratings with line widths down to 25 nm were patterned in 500 nm-thick resist layers and semi-dense gratings with line widths down to 10 nm (40 nm pitch) were patterned in 250 nm-thick resist layers. The dense HSQ nanostructures were used as molds for gold electrodeposition, and the semi-dense HSQ gratings were iridium-coated by atomic layer deposition. We used these methods to produce Fresnel zone plates with extreme aspect ratio for scanning transmission x-ray microscopy that showed excellent performance at 1.0 keV photon energy. PMID:20562479

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

2010-06-18

279

The 511 keV emission from positron annihilation in the Galaxy  

NASA Astrophysics Data System (ADS)

The first ?-ray line originating from outside the Solar System that was ever detected is the 511 keV emission from positron annihilation in the Galaxy. Despite 30 years of intense theoretical and observational investigation, the main sources of positrons have not been identified up to now. Observations in the 1990s with OSSE/CGRO (Oriented Scintillation Spectrometer Experiment on GRO satellite/Compton Gamma Ray Observatory) showed that the emission is strongly concentrated toward the Galactic bulge. In the 2000s, the spectrometer SPI aboard the European Space Agencys (ESA) International Gamma Ray Astrophysics Laboratory (INTEGRAL) allowed scientists to measure that emission across the entire Galaxy, revealing that the bulge-to-disk luminosity ratio is larger than observed at any other wavelength. This mapping prompted a number of novel explanations, including rather exotic ones (e.g., dark matter annihilation). However, conventional astrophysical sources, such as type Ia supernovae, microquasars, or x-ray binaries, are still plausible candidates for a large fraction of the observed total 511 keV emission of the bulge. A closer study of the subject reveals new layers of complexity, since positrons may propagate far away from their production sites, making it difficult to infer the underlying source distribution from the observed map of 511 keV emission. However, in contrast to the rather well-understood propagation of high-energy (>GeV) particles of Galactic cosmic rays, understanding the propagation of low-energy (MeV) positrons in the turbulent, magnetized interstellar medium still remains a formidable challenge. The spectral and imaging properties of the observed 511 keV emission are reviewed and candidate positron sources and models of positron propagation in the Galaxy are critically discussed.

Prantzos, N.; Boehm, C.; Bykov, A. M.; Diehl, R.; Ferrire, K.; Guessoum, N.; Jean, P.; Knoedlseder, J.; Marcowith, A.; Moskalenko, I. V.; Strong, A.; Weidenspointner, G.

2011-07-01

280

Compton Profiles of Silver with 662 keV ?-Rays  

NASA Astrophysics Data System (ADS)

The isotropic Compton profiles of Ag for two thicknesses, 2 mm and 4 mm, have been measured by means of 662 keV ?-rays from Cs137 source. A HpGe detector with resolution of 190 eV at 5.9 keV was used to detect the backward scattering photons. Comparison with the renormalized-free-atom model calculations was made, and the agreement between the experimental and the calculated values has been found to be good for the electron configuration 4d105s1.

Chang, Chu-Nan; Lee, Syh-Bin; Chen, Chuhn-Chih

1991-12-01

281

Xenon-neon gas proportional-scintillation counters for X-rays below 2 keV: experimental results  

Microsoft Academic Search

The energy spectra of X-rays with energies below 2 keV measured with standard Xe filled gas proportional-scintillation counters at atmospheric pressure exhibit a distorted tail toward the low energy region, due to the loss of electrons to the detector entrance window. In this framework, a Monte Carlo simulation study taking into account these losses has previously investigated the use of

F. I. G. M. Borges; F. P. Santos; J. M. F. dos Santos; T. H. V. T. Dias; P. J. B. M. Rachinhas; C. A. N. Conde

2003-01-01

282

Fluorescence from Mixtures of Noble Gases and Various Substrates, Induced by Ns Pulses of 600 KeV Electrons.  

National Technical Information Service (NTIS)

We measured relative energy transfer probabilities from excited noble gas species, produced at high pressure (5-20b) by short (2 ns) pulses of 600 keV electrons, to a variety of substrates. Fluorescence spectra were recorded in two modes, (a) wavelength d...

S. H. Bauer J. Krasinski

1980-01-01

283

Quantitative uptake measurements of I-131 (364 keV) within the tomographic plane of a specially collimated SPECT system  

Microsoft Academic Search

The use of SPECT for uptake measurements requires a linear relationship between the measured counts within a tomographic plane and its activity distribution. Many factors influence this relationship, and these include filter type and attenuation correction methods. However, for higher photon energy (I-131, 364 keV), photon penetration through the collimator or detector shielding may degrade, for example, the tomographic plane

L. P. Clarke; C. B. Saw; L. K. Leong; A. N. Serafini

1984-01-01

284

Measurement of the p(n,?)d reaction cross section between En = 100 and 350 keV  

NASA Astrophysics Data System (ADS)

The measurement of p(n,?)d reaction cross section has been performed at the neutron energies between 100 and 350 keV using the pulsed neutrons produced by the 7Li(p,n)7Be reaction and detecting the prompt ?-ray from this reaction with an anti-Compton NaI(TI) spectrometer.

Tomyo, A.; Nagai, Y.; Suzuki, T. S.; Kikuchi, T.; Shima, T.; Kii, T.; Igashira, M.

2003-05-01

285

KevJumba and the Adolescence of YouTube  

ERIC Educational Resources Information Center

|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

Saul, Roger

2010-01-01

286

8 keV x-ray zone plates.  

National Technical Information Service (NTIS)

Sputtered-sliced transmissive x-ray zone plates consisting of concentric rings of Al and Cu have been fabricated and tested using the 8.04 keV k-(alpha) line from Cu. Due to the need for high aspect ratios for this 1.54 (Angstrom) radiation, magnetron spu...

R. M. Bionta E. Ables O. Clamp O. D. Edwards P. C. Gabriele

1989-01-01

287

Studies on KeV and EV Electrons in Solids.  

National Technical Information Service (NTIS)

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 experime...

J. Schou

1979-01-01

288

APEX' Positive Evidence for Sharp 800 keV Pairs  

NASA Astrophysics Data System (ADS)

The APEX(I. Ahmad, et al., Phys.Rev.Lett. 75, 2658 (1995).) U+Th pair data is analyzed. The best chi-squared fit to this data describes a smooth background plus a sharp pair line consisting of 123 pairs of width 23 keV at 793 keV. This fit is significantly better than the background-only description which the APEX report presented. Furthermore, its strength conforms to the upper bound imposed by the APEX analysis. Thus, it contradicts nothing in the APEX report, except that it is much smaller than their a priori expectations for its strength. The data even imposes positive lower bounds of 23 sharp pairs per 20 keV near 800 keV at 99.0% Confidence Level. It is therefore untenable to argue from the APEX data against the existence of sharp pairs. Ratios of various comparable pair counts from the APEX and EPOS(P.Salabura, et al., Phys.Lett. B245, 153 (1990).) experiments are cited to show empirically that both their background and their sharp pair distributions are mutually consistent; furthermore the two pair databases are shown to be of comparable statistical potency, so that conflicts, if any, between them can be resolved only by other independent evidence.

Griffin, James J.

1997-04-01

289

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

SciTech Connect

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

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

2009-09-15

290

Astrophysical S factor for the B11(d,n)C12 reaction below 135 keV  

NASA Astrophysics Data System (ADS)

The B11(d,n)C12 reaction was studied using deuteron beams of 120 160 keV to determine the absolute astrophysical S factors and cross sections for the n0 and n1 neutron groups. The slopes of the S factors are consistent with zero for both the n0 and n1 cases. The measured S factor for the sum of both neutron groups at c.m. energies below 135 keV is S=3180480 keV b. A DWBA calculation is able to reproduce the ratio of the S factors found here to those obtained in a recent study of the Li7(d,n0,1)Be8 reaction.

Parpottas, Y.; Ahmed, M. W.; Blackston, M. A.; France, R. H., III; Perdue, B. A.; Prior, R. M.; Sabourov, A.; Spraker, M. C.; Weller, H. R.

2006-07-01

291

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

NASA Astrophysics Data System (ADS)

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

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

2013-09-01

292

Relative dissociation fractions of SF6 under impact of 15-keV to 30-keV H? and C? negative ions  

NASA Astrophysics Data System (ADS)

The relative dissociation fractions for the production of fragment ions and ion pairs of SF6 are studied for H? and C? impact in the energy range from 15 to 30 keV. Recoil ions (SF4+, SF3+, SF2+, SF+, S+, F+, SF42+, SF22+) and ion pairs (SF3++F+,SF2++F+,SF++F+,S++F+, F++F+) are detected and identified in coincidence with scattered projectiles in two charge states (q=0 and q=+1) by using a time-of-flight spectrometer. The relative dissociation fractions are energy dependent for both single-electron-loss (SL) channel and double-electron-loss (DL) channel processes for certain negative ions. It is also found that the relative dissociation fractions for DL are larger than those for SL. In addition, the degree of fragmentation will become greater with a larger mass number of the projectiles at the same impact energy for the same electron-loss channel. A comparison of the time-of-flight spectra is made between that under negative-ion impact and that under electron impact, and it is found that the probability of production of SFn+ ions with n odd is higher than that of similar ions with n even, and the probability of production of SFn2+ ions with n even is higher than that of similar ions withn odd under H?, C?, positive-ion, and electron impact. We analyze this interesting phenomenon from the bond-dissociation energies of SFn+ and SFn2+. We also analyze the coincident time-of-flight spectra of two fragment ions resulting from double ionization of SF6 by H? and C? impact and describe the major dissociation pathways of SF62+ for H? and C? impact in the energy range from 15 to 30 keV.

Zhao, Zilong; Li, Junqin; Zhang, Xuemei

2013-10-01

293

NBS standard neutron beams extend energy range for personnel dosimeter calibrations  

Microsoft Academic Search

At the NBS reactor researchers have used filter techniques to produce neutron beams for dosimeter calibration at energies of 2 keV, 24 keV, and 144 keV. The 144-keV beam provides an overlap with existing calibration facilities, the 24-keV beam fixes the low-energy end of these facilities, and the 2-keV beam provides the only calibration point available in the intermediate energy

R. B. Schwartz; I. G. Schroder

1977-01-01

294

CCD imaging from 20 eV to 8 keV  

SciTech Connect

Pulsed x-ray diagnostics operating in the kilovolt and sub-kilovolt regimes are required in the study of x-ray laser schemes. Sensitivity and dynamic range measurements are presented for position-sensitive detector systems, designed and optimized for these spectral regions. Both systems employ cooled, multi-pinned phase CCD's for image capture. For photon energies from 20 eV to 1 keV (where direct detection with front illuminated devices is inadequate), a phosphor transducer is used, coupled to the CCD via a fiber optic faceplate with 6 {mu}m diameter channels. From 800 eV to 8 keV, direct detection of electron-hole pairs generated in the depletion region of the CCD is employed. The systems have been tested with single-shot sensitivity using a 10 Hz, 2J/7{center_dot}5 ns injection seeded Nd:YAG laser operated at 2{omega}, using Bragg crystal and flat field grazing incidence spectrometers to monitor the resonance emission from aluminium and carbon targets irradiated at {approx}10{sup 12} W cm{sup -2}. At 182 A, the sensitivity and dynamic range are enhanced with respect to that for a standard photographic detector, by factors of 8 and 300 respectively. An absolute calibration of the 700 eV-8 keV detector system performed at 1.6 keV, has been shown to agree with a calculation of sensitivity based on photo-absorption data. For this system, the enhancement in sensitivity and dynamic range over direct exposure x-ray film is 175 and 43 respectively.

MacPhee, A. G.; Lewis, C. L. S. [Department of Pure and Applied Physics, The Queens University of Belfast, BT7 1NN, Northern Ireland (United Kingdom)

1995-05-01

295

Energetic (keV) Ionosphere-Origin Ions Found Between R= 2 and 23 R E  

NASA Astrophysics Data System (ADS)

With the flight of ion composition instruments on the Polar satellite, beginning some eight years ago, adding to several earlier missions of varied orbits, we now have essentially contiguous altitude records of the outflow of energized ionospheric ions from R= 2 R E (geocentric) to R= 23 R E, at least in the energy range from a few tens of eV/e to a few tens of keV/e. Magnetotail ion composition measurements in that energy range were first made more than 20 years ago during the ISEE mission (within 23 R E) and are again being made with the Cluster satellites (within 20 R E). According to the several years of ISEE measurements, the nearly omnipresent, singly charged oxygen ions, in particular, have a broad energy distribution within the tail plasma sheet, typically averaging about 3-5 keV. This may be contrasted with mean O+ energies of only 0.2-0.4 keV observed in the ion outflow at R 2 R E by the Polar TIMAS instrument. The same instrument finds the O+ mean energy to have increased to 1 keV or more by the time the ions have reached R 4-9 R E, while the total rate of O+ outflow (ions per second) above the nominal 15 eV minimum energy (plus spacecraft potential) has increased about fivefold. An important part of this progressive energization is transverse acceleration across the geomagnetic field lines. As will be shown, this process is sometimes resolved within the O+ gyro period by the TIMAS instrument at these high altitudes. Early TIMAS results suggest that this kind of acceleration is intermittent and explosive and arguably caused by magnetic field-aligned space charge structures associated with earthward bursts of hot and filamentary magnetospheric plasma. The TIMAS data also imply that ionospheric ions are directly injected into the ring current region, but the very energetic O+ (~100 keV) that is known to be a large component of the storm-time ring current has most likely arrived from the plasma sheet, undergoing adiabatic betatron and Fermi acceleration.

Lennartsson, O. W.

2004-05-01

296

Relative detection efficiency of back- and front-illuminated charge-coupled device cameras for x-rays between 1 keV and 18 keV  

NASA Astrophysics Data System (ADS)

High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer using for the detection of the diffracted photons either a back-illuminated charge-coupled device (CCD) camera or a front-illuminated one. For each CCD the main x-ray emission lines (e.g., K?, K?, L?, and L?) of a variety of elements were measured in order to probe the performances of the two detectors between 1 and 18 keV. From the observed x-ray lines the linearity of the energy response, the noise level, the energy resolution, and the quantum efficiency ratio of the two CCDs were determined.

Szlachetko, J.; Dousse, J.-Cl.; Hoszowska, J.; Berset, M.; Cao, W.; Szlachetko, M.; Kav?i?, M.

2007-09-01

297

ENA (E>5 keV) Images from Cassini and Voyager ``ground truth'': Suprathermal Pressure in the Heliosheath  

NASA Astrophysics Data System (ADS)

Maps of energetic neutral atoms (ENA) of the heliosphere from Cassini [1] have been constructed spanning the energy range ~5<=E<=55 keV, and show a ``Belt'' in the sky of ~100 FWHM. Similarly, maps >6 keV have been obtained by the IBEX mission [2] and show a ``Ribbon'' that is narrower than the Belt and inclined to it in both ecliptic latitude (~25) and longitude (~30). The overlap in energy between Voyager ions [3] and Cassini ENA intensities (averaged over the ENA line of sight) enables us to deduce ion fluxes in the heliosheath, thus providing a continuous spectrum 5<=E<=4000 keV. These measurements are then used to estimate the local partial pressure over this energy range (~0.1 pPa), suggesting ?>25 [4] and the thickness of the heliosheath (~50 AU). Using a simulated PUI distribution [5], we estimate the E<6 keV contribution to be ~0.12 pPa. The balance of the non-thermal pickup ion (PUI) pressure against the stagnation pressure of the interstellar plasma and the local interstellar magnetic field (ISMF) at the nose of the heliopause implies an upper bound on the ISMF of ~0.64 nT.

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

2010-12-01

298

PET attenuation coefficients from CT images: experimental evaluation of the transformation of CT into PET 511keV attenuation coefficients  

Microsoft Academic Search

The CT data acquired in combined PET\\/CT studies provide a fast and essentially noiseless source for the correction of photon attenuation in PET emission data. To this end, the CT values relating to attenuation of photons in the range of 40-140 keV must be transformed into linear attenuation coefficients at the PET energy of 511 keV. As attenuation depends on

C. Burger; G. Goerres; S. Schoenes; A. Buck; A. Lonn; G. von Schulthess

2002-01-01

299

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

Microsoft Academic Search

A comparison of 24.5 keV neutron fluence standards was organized by Section III (Neutron Measurements) of the Comit Consultatif des Rayonnements Ionisants, (CCRI). The exercise involved the circulation of a set of three different-diameter Bonner spheres for calibration in fields with energies around 24.5 keV. The fields were produced using four different methods of neutron production. The responses (counts per

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

2010-01-01

300

A single W/B4C transmission multilayer for polarization analysis of soft x-rays up to 1keV.  

PubMed

A transmission W/B(4)C multilayer has been designed and characterized which shows significant phase retardation up to a photon energy of 1 keV, when operated near the Bragg condition. This allows, for the first time, the full polarization vector of soft x-radiation to be measured up to 1 keV in a self-calibrating method. Quantitative polarimetry is now possible across the 2p edges of all the transition metals. PMID:20052255

MacDonald, Michael A; Schfers, Franz; Gaupp, Andreas

2009-12-01

301

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

NASA Astrophysics Data System (ADS)

The K-L and K-M resonant Raman scattering (RRS) cross-sections have been measured for the first time at the 59.536 keV photon energy in the 70Yb (BK=61.332 keV), 71Lu (BK=63.316 keV) and 72Hf (BK=65.345 keV) elements; BK being the K-shell binding energy. The K-L and K-M RRS measurements have been performed at the 59 and 133 angles, respectively, to avoid interference of the Compton-scatter peak. The Rayleigh and Compton scattering cross-sections for the 59.536 keV ?-rays have also been measured at both the angles in the atomic region 1<=Z<=92. Measurements were performed using the reflection-mode geometrical arrangements involving the 241Am radioisotope as photon source and planar Si(Li) and HPGe detectors. Ratios of the K-M and K-L RRS cross-sections in Yb, Lu and Hf are in general lower than that of the fluorescent K?1,3,5 (K-M) and K? (K-L) X-ray transition probabilities. Theoretical Rayleigh scattering cross-sections based on the modified form-factors (MFs) corrected for the anomalous scattering factors (ASFs) and the S-matrix calculations are on an average ~15% and ~6% higher, respectively, at the 133 angle and exhibit good agreement with the measured data at the 59 angle. Larger deviations ~30% and ~20%, respectively, are observed at the 133 angle for the 64Gd, 66Dy, 67Ho and 70Yb elements having the K-shell binding energy in vicinity of the incident photon energy. The measured Compton scattering cross-sections are in general agreement with those calculated using the Klein-Nishina cross-sections and the incoherent scattering function.

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

2004-09-01

302

Optimization of phosphor screens for charge coupled device based detectors and 7{endash}34 keV x-rays  

SciTech Connect

Phosphor screens convert x-ray images to visible light images in two-dimensional charge coupled device (CCD) based detector systems used for x-ray diffraction. Some experimental and theoretical aspects of phosphor screen performance are described in this article. The efficiencies of x-ray-to-light conversion were measured using a CCD camera for transmission phosphor screens fabricated from two different phosphor powders, Y{sub 2}O{sub 2}S:Eu (P22R) and Gd{sub 2}O{sub 2}S:Tb (P43), for screen mass thicknesses of 3{endash}50 mg/cm{sup 2} and for x-ray energies of 7{endash}34 keV. A model was developed and evaluated for the dependence of the emitted light brightness on screen thickness and x-ray energy. Inputs to the model are x-ray absorption coefficients and light attenuation versus thickness data, which were determined experimentally for the phosphors and found to be dominated by scattering rather than absorption. The angular distribution of emitted light, was found to be nearly Lambertian. Broadening of image features in the x-ray-to-visible-light conversion by phosphors for 19.6 keV x-rays was found to increase approximately linearly with phosphor screen thicknesses in the range of 30{endash}160 {mu}m, but with a minimum width of 110 {mu}m for P22R phosphor and 70 {mu}m for P43 phosphor. In the range of 7{endash}15 keV, maximum brightness was obtained for P43 phosphor screens of about 10 mg/cm{sup 2} mass thickness (60 {mu}m). For P22R screens, the thickness for maximum brightness increased from about 8 mg/cm{sup 2} (50 {mu}m) for 7 keV to more than 46 mg/cm{sup 2} (210 {mu}m) for 15 keV. For 7 keV the maximum brightnesses for P22R and P43 phosphors were about the same. For 10 keV the maximum brightness for P43 phosphor was about 60{percent} greater than the maximum brightness for P22R phosphor samples tested. For 15 keV the maximum brightness for P43 phosphor was again about 60{percent} greater than that for the P22R samples tested. (Abstract Truncated)

Wang, P.; Cargill, G.S. III [Department of Chemical Engineering, Materials Science and Mining Engineering, Columbia University, New York, New York 10027 (United States)

1997-02-01

303

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

NASA Astrophysics Data System (ADS)

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.

Lee, J. J.; Parks, G. K.; Lee, E.; Tsurutani, B. T.; Hwang, J.; Cho, K. S.; Kim, K.-H.; Park, Y. D.; Min, K. W.; McCarthy, M. P.

2012-11-01

304

Hydrogen. Stopping powers and ranges in all elements. [10 keV to 20 MeV (per amu); book  

Microsoft Academic Search

Absolute experimental energy-loss data for hydrogen are presented over the energy range E\\/amu = 10 keV to 20 MeV. Data were fitted to analytical functions, the parameters of which are given together with the experimental data. An attempt was made to interpolate the fitting parameters to elements for which there are no experimental data. Fitted stopping powers were integrated to

H. H. Andersen; J. F. Ziegler

1977-01-01

305

Zeptosecond High Harmonic keV X-Ray Waveforms Driven by Midinfrared Laser Pulses  

NASA Astrophysics Data System (ADS)

We demonstrate theoretically that the temporal structure of high harmonic x-ray pulses generated with midinfrared lasers differs substantially from those generated with near-infrared pulses, especially at high photon energies. In particular, we show that, although the total width of the x-ray bursts spans femtosecond time scales, the pulse exhibits a zeptosecond structure due to the interference of high harmonic emission from multiple reencounters of the electron wave packet with the ion. Properly filtered and without any compensation of the chirp, regular subattosecond keV waveforms can be produced.

Hernndez-Garca, C.; Prez-Hernndez, J. A.; Popmintchev, T.; Murnane, M. M.; Kapteyn, H. C.; Jaron-Becker, A.; Becker, A.; Plaja, L.

2013-07-01

306

keV particle bombardment of semiconductors: A molecular-dynamics simulation  

SciTech Connect

Molecular-dynamics simulations have been performed for the keV particlebombardment of Si/l brace/110/r brace/ and Si/l brace/100/r brace/ using a many-body potential developed byTersoff. Energy and angle distributions are presented along with an analysis ofthe important ejection mechanisms. We have developed a computer logic that onlyintegrates the equations of motion of the atoms that are struck, thusdecreasing the computer time by a factor of 3 from a completemolecular-dynamics simulation.

Smith, R.; Harrison, D. E., Jr.; Garrison, B. J.

1989-07-01

307

Generation of 0.4-keV femtosecond electron pulses using impulsively excited surface plasmons.  

PubMed

We demonstrate the generation of 0.4-keV, sub-27 fs electron pulses using low-intensity laser pulses from a Ti:sapphire oscillator through the excitation of surface plasmon waves on a time scale within the plasmon lifetime. Modeling of the ponderomotive electron pulse acceleration yields electron energy spectra that are in excellent agreement with the observed ones. Our work opens a doorway for time-resolved experimentation using low-power, high-repetition rate laser pulses. PMID:15525170

Irvine, S E; Dechant, A; Elezzabi, A Y

2004-10-28

308

Photon, Electron and Secondary Ion Emission from Single C60 keV Impacts  

PubMed Central

This paper presents the first observation of coincidental emission of photons, electrons and secondary ions from individual C60 keV impacts. An increase in photon, electron and secondary ion yields is observed as a function of C60 projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV-Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution.

Fernandez-Lima, F. A.; Eller, M. J.; Verkhoturov, S. V.; Della-Negra, S.; Schweikert, E. A.

2010-01-01

309

Photon, Electron and Secondary Ion Emission from Single C(60) keV Impacts.  

PubMed

This paper presents the first observation of coincidental emission of photons, electrons and secondary ions from individual C(60) keV impacts. An increase in photon, electron and secondary ion yields is observed as a function of C(60) projectile energy. The effect of target structure/composition on photon and electron emissions at the nanometer level is shown for a CsI target. The time-resolved photon emission may be characterized by a fast component emission in the UV-Vis range with a short decay time, while the electron and secondary ion emission follow a Poisson distribution. PMID:21218166

Fernandez-Lima, F A; Eller, M J; Verkhoturov, S V; Della-Negra, S; Schweikert, E A

2010-12-16

310

Ionization and Fragmentation of 5-Chlorouracil induced by 100 keV protons collisions  

SciTech Connect

We present preliminary experimental results on the dissociation of singly and doubly ionized 5-Chlorouracil induced by collisions with proton of 100 keV energy. Multiple coincidence techniques are used to detect the ionic fragments from single dissociation events. This enables a thorough analysis of kinetic momentums of the charged and neutral species involved in the dissociation. In many cases, this leads to the establishment of the scenario the molecule undergoes after ionization as well as the determination of the nature of intermediate (undetected) species. In other cases, the dissociation scenario cannot be unambiguously identified and further analysis as well as theoretical support is needed.

Cafarelli, Pierre; Champeaux, Jean-Philippe; Le Padellec, Arnaud; Moretto-Capelle, Patrick; Rabier, Julien; Sence, Martine [Laboratoire Collisions, Agregats, Reactivite, UMR 5589, CNRS-Universite Paul Sabatier Toulouse 3, IRSAMC, 31062 Toulouse Cedex 9 (France); Carcabal, Pierre [Laboratoire Collisions, Agregats, Reactivite, UMR 5589, CNRS-Universite Paul Sabatier Toulouse 3, IRSAMC, 31062 Toulouse Cedex 9 (France); Laboratoire de Photophysique Moleculaire CNRS, UPR 3361, Batiment 210, Universite Paris Sud, 91405 Orsay cedex (France)

2008-12-08

311

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

NASA Astrophysics Data System (ADS)

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

Kumar, A.; Shahi, J. S.; Garg, M. L.; Puri, S.; Mehta, D.; Singh, N.

2001-10-01

312

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

NASA Astrophysics Data System (ADS)

We report on the development of an innovative CdTe detector plane (DPIX) optimized for the detection and localization of gamma-ray bursts in the X-ray band (below 100 keV). DPIX is part of an R&D program funded by the French Space Agency (CNES). DPIX builds upon the heritage of the ISGRI instrument, currently operating with great success on the ESA INTEGRAL mission. DPIX is an assembly of 200 elementary modules (XRDPIX) equipped with 32 CdTe Schottky detectors (4 4 mm 2, 1 mm thickness) produced by ACRORAD Co., Ltd. in Japan. These detectors offer good energy response up to 100 keV. Each XRDPIX is readout by the very low noise front-end electronics chip IDeF-X, currently under development at CEA/DSM/DAPNIA. In this paper, we describe the design of XRDPIX, the main features of the IDeF-X chip, and will present preliminary results of the reading out of one CdTe Schottky detector by the IDeF-X V1.0 chip. A low-energy threshold around 2.7 keV has been measured. This is to be compared with the 12-15 keV threshold of the ISGRI-INTEGRAL and BAT-SWIFT instruments, which both use similar bulk detector material.

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

313

OSSE Mapping of 511 keV Annihilation Radiation  

NASA Astrophysics Data System (ADS)

The OSSE instrument on-board the CGRO is the first instrument capable of mapping the 511 keV emission that results from positron-electron annihilation. Based upon the findings of earlier, large Field of View instruments, the bulk of the mapping effort has concentrated upon the galactic center region. This effort has successfully detected emission from an extended region near the galactic center, emission from the galactic plane, and a recently reported enhancement of emission from positive latitudes (Purcell et al. 1998). Nonetheless, the OSSE instrument has observed other regions of the sky with considerable exposure, regions expected to be devoid of 511 keV emission at levels detectable by OSSE. From a study of three such regions (Virgo, South Galactic Pole, North Ecliptic Pole), as well as from a collection of AGN observations,a small scan angle dependence of the fitted 511 keV line emission was detected. We combine an expanded data set with recent (cycle 7 and cycle 8) observations, and apply the scan-angle correction, to produce maps of both the galactic center region and the Virgo region. We show these maps, and for the galactic center map, we discuss the features of this map with relation to previous maps.

Milne, P. A.; Kurfess, J. D.; Leising, M. D.; Dixon, D. D.; Purcell, W. R.

1999-04-01

314

ART: Surveying the Local Universe at 2-11 keV  

NASA Astrophysics Data System (ADS)

The Astronomical Rntgen Telescope (ART) is a medium-energy x-ray telescope system proposed for the Russian-led mission Spectrum Rntgen-Gamma (SRG). Optimized for performance over the 2-11-keV band, ART complements the softer response of the SRG prime instrument - the German eROSITA x-ray telescope system. The anticipated number of ART detections is 50,000 - with about 1,000 heavily-obscured (NH > 31023 cm-2) active galactic nuclei (AGN) - in the SRG 4-year all-sky survey, plus a comparable number in deeper wide-field (500 deg2 total) surveys. ART's surveys will provide a minimally-biased, nearly-complete census of the local Universe in the medium-energy x-ray band (including Fe-K lines), at CCD spectral resolution. During long (�-ks) pointed observations, ART can obtain statistically significant spectral data up to about 15 keV for bright sources and medium-energy x-ray continuum and Fe-K-line spectra of AGN detected with the contemporaneous NuSTAR hard-x-ray mission.

O'Dell, Stephen L.; Ramsey, B. D.; Adams, M. L.; Areviev, V.; Brandt, W. N.; Buntov, M.; Elsner, R. F.; Grigorovich, S.; Gubarev, M. V.; Hasinger, G.; Lapshov, I.; Litvin, D.; Meidinger, N.; Pavlinsky, M.; Predehl, P.; Revnivtsev, M.; Romaine, S. E.; Sazonov, S.; Semena, N.; Swartz, D. A.; Tkachenko, A.; Urry, C. M.; Vikhlinin, A.; Weisskopf, M. C.

2008-03-01

315

Iridium optical constants from x-ray transmission measurements over 2 to 12 keV  

NASA Astrophysics Data System (ADS)

Precise transmission measurements of free standing iridium foils and of iridium coatings supported on thin polyimide film have been made at the X8 beamline of the National Synchrotron Light Source, at energies from 2 to 12 keV. These measurements were conducted to provide iridium optical constants in support of NASA's Advanced X-ray Astrophysics Facility (AXAF). Transmission data were collected at small energy increments across iridium M and L absorption edges to study detailed edge structures. From these data, the imaginary components of the index of refraction were computed. The data also allows computation of the real parts, using the Kramers-Kronig dispersion integral. Preliminary results indicate a measurement accuracy of better than one percent for transmission. Absorption coefficients deviate by varying amounts from values predicted from Henke data table, which is consistent with the accuracy claimed for those table.s Nonuniform thickness in our iridium foils may be a source of errors in our analysis and improved foils are being sought. Additional measurements will also be needed with foils of different thickness to account and correct for possible effects of sample thickness on the determination of absorption edge fine structure. To our knowledge, transmission measurements of this degree of accuracy and precision have not been previously reported in the literature for iridium in the 2- 12 keV energy range.

Harris, Bernard; Graessle, Dale E.; Fitch, J. J.; Juda, Jiahong Z.; Blake, Richard L.; Schattenburg, Mark L.; Gullikson, Eric M.

1996-07-01

316

Cassini ENA (E > 5 keV) Heliosphere Belt and overlapping in-situ Voyager measurements: Pressure and ISMF implications  

NASA Astrophysics Data System (ADS)

Maps of energetic neutral atoms (ENA) of the heliosphere from Cassini (Krimigis et al, 2009) have been constructed spanning the energy range ~ 5 ? E ? 55 keV, and show a Belt in the sky of ~ 100 FWHM. ENA maps < 6 keV have been obtained by the IBEX mission (McComas et al, 2009) and show a Ribbon that is narrower than the Belt and inclined to it in both ecliptic latitude (~25) and longitude (~30). The overlap in energy between Voyager ions (Decker et al, 2009) and Cassini ENA intensities (averaged over the ENA line of sight) enables us to deduce ion fluxes in the heliosheath, thus providing a continuous spectrum 5 ? E ? 4000 keV. The Cassini ENAs provide a smooth transition spectrum between the accelerated pickup ions (PUI) and the well-established Voyager LECP j?E-1.5 tail at E > 28 keV, and lead to a thickness of the heliosheath of ~ 50 AU. These measurements are then used to estimate the local partial pressure over this energy range (~ 0.1 pPa), suggesting ? > 25 locally. Using a simulated PUI distribution (Giacalone and Decker, 2010) we estimate the E < 6 keV contribution to the pressure to be ~ 0.12 pPa. Assuming constant total pressure throughout the heliosheath, the balance of the non-thermal pickup ion (PUI) pressure against the stagnation pressure of the interstellar plasma and the hydrostatic pressure of the local interstellar magnetic field (ISMF) at the nose of the heliopause implies an upper bound on the ISMF of ~ 0.64 nT. Implications on the shape of the heliosphere are discussed.

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

2010-12-01

317

Metastable dark matter mechanisms for INTEGRAL 511 keV {gamma} rays and DAMA/CoGeNT events  

SciTech Connect

We explore dark matter mechanisms that can simultaneously explain the galactic 511 keV gamma rays observed by INTEGRAL/SPI, the DAMA/LIBRA annual modulation, and the excess of low-recoil dark matter candidates observed by CoGeNT. It requires three nearly degenerate states of dark matter in the 4-7 GeV mass range, with splittings, respectively, of order MeV and a few keV. The top two states have the small mass gap and transitions between them, either exothermic or endothermic, and can account for direct detections. Decays from one of the top states to the ground state produce low-energy positrons in the Galaxy whose associated 511 keV gamma rays are seen by INTEGRAL. This decay can happen spontaneously, if the excited state is metastable (longer lived than the age of the Universe), or it can be triggered by inelastic scattering of the metastable states into the shorter-lived ones. We focus on a simple model where the dark matter is a triplet of an SU(2) hidden sector gauge symmetry, broken at the scale of a few GeV, giving masses of order < or approx. 1 GeV to the dark gauge bosons, which mix kinetically with the standard model hypercharge. The purely decaying scenario can give the observed angular dependence of the 511 keV signal with no positron diffusion, while the inelastic scattering mechanism requires transport of the positrons over distances {approx}1 kpc before annihilating. We note that an x-ray line of several keV in energy, due to single-photon decays involving the top dark matter states, could provide an additional component to the diffuse x-ray background. The model is testable by proposed low-energy fixed-target experiments.

Cline, James M.; Frey, Andrew R.; Chen, Fang [Physics Department, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)

2011-04-15

318

Study of keV radiation properties of Mo and Ti X-pinch plasma sources using a pinhole transmission grating spectrometer  

NASA Astrophysics Data System (ADS)

The properties of keV x-ray radiations from Mo and Ti X-pinch plasma sources at the current of 800 kA were investigated by a pinhole transmission grating spectrometer. The spectrometer was characterized by a high linear dispersion rate (2.9 A?/mm), and from its time-integrated diffraction images, rich information about the X-pinch sources (e.g., source number, source size, and absolute spectra) could be obtained. Multiple hot spots were produced in all the Mo tests with loads made of two or four 25 ?m wires with or without a shunt wire, and obvious increases both in the radiation intensity and in the source size around the spectral region of 2.6 keV were observed. In Ti X-pinch tests, a single keV x-ray burst with a source size of ~200 ?m and a time duration of ~200 ps in full width at half maximum was obtained using a load made of two 50 ?m wires plus a shunt wire. The intensity of x-rays decreased sharply from ~1011 photon eV-1 sr-1 at 1 keV to ~108 photon eV-1 sr-1 at 4 keV. The energy-dependent source size in the band of 1-4 keV is less than 100 ?m and seemed to shrink quickly as x-ray energy increases.

Li, Jing; Deng, Jian-Jun; Xie, Wei-Ping; Huang, Xian-Bin; Yang, Li-Bing; Zhou, Shao-Tong; Zhu, Xiao-Li; Duan, Shu-Chao; Zhang, Si-Qun; Dan, Jia-Kun

2010-07-01

319

Fragmentation of singly charged adenine induced by neutral fluorine beam impact at 3 keV  

NASA Astrophysics Data System (ADS)

The fragmentation scheme of singly charged adenine molecule (H5C5N5+) has been studied via neutral fluorine impact at 3 keV. By analyzing in correlation the kinetic energy loss of the scattered projectile F- produced in single charge transfer process and the mass of the charged fragments, the excitation energy distribution of the parent adenine molecular ions has been determined for each of the main dissociation channels. Several fragmentation pathways unrevealed in standard mass spectra or in appearance energy measurements are investigated. Regarding the well-known hydrogen cyanide (HCN) loss sequence, we demonstrate that although the loss of a HCN is the dominant decay channel for the parent H5C5N5+ (m = 135), the decay of the first daughter ion H4C4N4+ (m = 108) involves not only the HNC (m = 27) loss but also the symmetric breakdown into two dimers of HCN.

Chen, L.; Brdy, R.; Bernard, J.; Montagne, G.; Allouche, A. R.; Martin, S.

2011-09-01

320

Blistering of silicon crystals by low keV hydrogen and helium ions  

NASA Astrophysics Data System (ADS)

The blistering of Si wafers with (100), (110), and (111) orientations, induced by implantation of low energy (5-8 keV) H and/or He ions, was studied. Our earlier work had used either pure H implants at high dose (51016 cm-2) or low dose coimplantation (11016 H cm-2+11016 He cm-2). Here we study pure He implantation, and coimplantation with variable He/H dose ratio, in order to understand the roles of H and He, in the hope of improving the blistering efficiency (as used, e.g., in the Smart-cut process). After room temperature implantation, the samples were vacuum annealed in three steps at 500, 550, and 600 C. At each step, the development of blistering and exfoliation was quantified by scanning electron microscopy (``exfoliation'' is here used to mean blister explosion). We found that the thermal budget required for blistering is higher than for comparable doses of high energy (>30 keV) ions. On the Si(110) surface, H blistering is very weak, He blistering is the strongest, but exfoliation absent. On Si(111), H blistering is the strongest, He the weakest, but exfoliation a maximum. Si(100) shows intermediate behavior. Weak H blistering correlates with premature H2 desorption. H+He coimplantation efficiently increases the degree of blistering and, to some extent, exfoliation.

Qian, C.; Terreault, B.

2001-11-01

321

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

SciTech Connect

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

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

1997-10-01

322

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

SciTech Connect

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.

Not Available

2011-08-17

323

Proposed FNAL 750 KeV Linac Injector Upgrade  

SciTech Connect

The present FNAL linac H{sup -} injector has been operational since 1978 and consists of a magnetron H{sup -} source and a 750 keV Cockcroft-Walton Accelerator. The proposed upgrade to this injector is to replace the present magnetron source having a rectangular aperture with a circular aperture, and to replace the Cockcroft-Walton with a 200 MHz RFQ. Operational experience at other laboratories has shown that the upgraded source and RFQ will be more reliable and require less manpower than the present system.

Tan, C.Y.; Bollinger, D.S.; Schmidt, C.W.; /Fermilab

2009-04-01

324

The G-Factor of the 305 Kev State of 48V.  

National Technical Information Service (NTIS)

The g-factor of the 305 keV state of the doubly odd nucleus V48 was determined by observing the rotation of the 116 keV 305 keV angular correlation in strong external magnetic fields. Liquid sources as well as Cr 48 sources embedded in the lattice of meta...

E. Bodenstedt H. W. Flender K. Auerbach J. Braunsfurth M. Maier

1966-01-01

325

A model of the intrinsic efficiency of a time-of-flight spectrometer for keV ions  

NASA Astrophysics Data System (ADS)

We have constructed a first-order model of the intrinsic efficiency of a time-of-flight spectrometer for medium energy ions. The spectrometer uses secondary electrons from a thin carbon foil to generate a start signal and ion impact on a microchannel plate to generate the stop signal. The model includes the effects of the secondary electron yield, multiple scattering in the foil, and the response of the individual microchannel plates which comprise the instrument. We describe the model and the variation of the predicted efficiency with model parameters. Comparisons with measured efficiencies for several ions and energies ranging from 40 keV H to 500 keV O indicate that the model's predictive power is satisfactory for interpreting the results of routine surface analyses.

Weller, Robert A.; Arps, James H.; Pedersen, Diane; Mendenhall, Marcus H.

1994-12-01

326

Feasibility of transmission x-ray microscopy at 4 keV with spatial resolutions below 150 nm  

NASA Astrophysics Data System (ADS)

The feasibility of a transmission x-ray microscope operating in the 3-7 keV photon energy range using phase zone plates (ZPs) has been tested. It has been demonstrated that, at a photon energy of 4 keV, structures smaller than 150 nm can be resolved with good contrast using exposure times in the second to minute range. A large diameter gold ZP was used as condenser and a tungsten ZP with an outermost zone width of 128 nm was used as a high spatial resolution imaging objective lens. Images with a field size of 1010 ?m2 were acquired using a charge coupled device camera optically coupled to a phosphor screen. The corresponding pixel size in the object plane was 70 nm.

Kaulich, B.; Oestreich, S.; Salome, M.; Barrett, R.; Susini, J.; Wilhein, T.; di Fabrizio, E.; Gentili, M.; Charalambous, P.

1999-12-01

327

The Spectrum of GRB 930131 (``Superbowl Burst'') from 20 KEV to 200 MEV  

NASA Astrophysics Data System (ADS)

We have constructed a broadband spectrum for GRB 930131 (the ``Superbowl Burst''), ranging from 20 keV to 200 MeV, by combining spectral information from the Gamma Ray Observatory's BATSE, COMPTEL, and EGRET instruments. We present general methods for combining spectra from different time intervals obtained by the same instrument as well as for combining spectra from the same time interval taken by different instruments. The resulting spectrum is remarkably flat (in nuF_nu-space) up to high energies. We find that the spectral shape can be successfully fitted by the shocked synchrotron emission model of Tavani. We present evidence that the flatness of the spectrum at high energies is not due to spectral time variability.

Bromm, Volker; Schaefer, Bradley E.

1999-08-01

328

Molecular dynamics simulations of 30 and 2 keV Ga in Si  

SciTech Connect

Focused Ga{sup +} ion beams are routinely used at high incident angles for specimen preparation. Molecular dynamics simulations of 2 and 30 keV Ga bombardment of Si(011) at a grazing angle of 88 deg. were conducted to assess sputtering characteristics and damage depth. The bombardment of atomically flat surfaces and surfaces with vacancies shows little energy transfer yielding ion reflection. The bombardment of surfaces with adatoms allows for the coupling of the energy of motion parallel to the surface into the substrate resulting in sputtering. The adatom and one other Si atom eject, and motion in the substrate occurs down to a depth of 13 A. Experimental evidence shows that sputtering is a reality, suggesting that an atomically flat surface is never achieved.

Giannuzzi, Lucille A.; Garrison, Barbara J. [FEI Company, 5350 NE Dawson Creek Drive, Hillsboro, Oregon 97124 (United States); Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802 (United States)

2007-09-15

329

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

SciTech Connect

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

Stoller, R.E.

1998-11-30

330

Active detection of shielded SNM with 60-keV neutrons  

SciTech Connect

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

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

2008-07-08

331

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

Microsoft Academic Search

Clover detector has been used as a Compton polarimeter to measure the linear polarization of ?-rays produced in heavy ion\\u000a fusion reaction. The polarization sensitivity of the clover detector has been measured over ?-ray energies ranging from 386\\u000a to 1368 ke V. The E1 multipolarity of the 1117 keV transition in 99Rh has been established using this polarimeter. This has

R. Palit; HC Jain; PK Joshi; S. Nagaraj; BVT Rao; SN Chintalapudi; S. S. Ghugre

2000-01-01

332

Observation of the 22.5keV Resonance in 149Sm by the Nuclear Lighthouse Effect  

Microsoft Academic Search

We have observed coherent nuclear resonant scattering of synchrotron radiation at the 22.5-keV resonance of 149Sm. High-speed rotational sample motion led to an angular deflection of the resonantly scattered radiation off the nonresonant primary beam. This allowed us to determine the resonance energy of the first excited nuclear level of 149Sm to be 22496(4) eV. Because of the angular deflection

R. Rhlsberger; K. W. Quast; T. S. Toellner; P. L. Lee; W. Sturhahn; E. E. Alp; E. Burkel

2001-01-01

333

The multipolarity of the K-forbidden 1094 keV gamma-transition in the decay of 172Lu  

Microsoft Academic Search

The multipolarity of the K-forbidden 1094 keV gamma-transition in the decay of 172Lu has been re-investigated by gammagamma angular correlation and linear polarization correlation measurements. The use of a Ge(Li) detector for the low-energy lines gave a good separation of the different cascades, and consequently more reliable results could be obtained than previous NaI(T1) measurements had given. We derived from

H. Blumberg; K.-H. Speidel; H. Schlenz; P. Weight; H. Huebel; P. Goettel; H.-F. Wagner; E. Bodenstedt

1967-01-01

334

Measurements of 4-10 keV x-ray production with the Z-Beamlet laser  

Microsoft Academic Search

In order to characterize the current backlighting capability of Sandia's Z-Beamlet laser (ZBL) over a range of high photon energies, we measured the x-ray conversion efficiency of the focused 527 nm ZBL beam into 4-10 keV x rays from He-like emission of the elements Sc through Ge (excluding Ga). The measurements approximated ZBL's nominal backlighting geometry and laser performance at

L. E. Ruggles; J. L. Porter; P. K. Rambo; W. W. Simpson; M. F. Vargas; G. R. Bennett; I. C. Smith

2003-01-01

335

Measurements of 410 keV x-ray production with the Z-Beamlet laser  

Microsoft Academic Search

In order to characterize the current backlighting capability of Sandias Z-Beamlet laser (ZBL) over a range of high photon energies, we measured the x-ray conversion efficiency of the focused 527 nm ZBL beam into 410 keV x rays from He-like emission of the elements Sc through Ge (excluding Ga). The measurements approximated ZBLs nominal backlighting geometry and laser performance at

L. E. Ruggles; J. L. Porter; P. K. Rambo; W. W. Simpson; M. F. Vargas; G. R. Bennett; I. C. Smith

2003-01-01

336

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

Microsoft Academic Search

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

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

1977-01-01

337

20-100 keV properties of cataclysmic variables detected in the INTEGRAL\\/IBIS survey  

Microsoft Academic Search

Analysis of INTEGRAL\\/IBIS survey observations has revealed that the rare intermediate polar and asynchronous polar cataclysmic variables (CVs) are consistently found to emit in the 20-100 keV energy band, whereas synchronous polars and the common non-magnetic CVs rarely do so. From the correlation of a candidate INTEGRAL\\/IBIS survey source list with a CV catalogue, 15 CV detections by IBIS have

E. J. Barlow; C. Knigge; A. J. Bird; A. J Dean; D. J. Clark; A. B. Hill; M. Molina; V. Sguera

2006-01-01

338

Rayleigh scattering of E = 465-2842 keV neutron capture ?-rays from Ta, In and Cu  

NASA Astrophysics Data System (ADS)

Gamma rays in the energy range 465-2842 keV, produced by the Ni(n,?) reaction using thermal neutrons from a nuclear reactor, are used to measure Rayleigh scattering at ? = 1.02 from targets of Ta, In and Cu having a wide range of Z values. Very good agreement is obtained with a theoretical approximation based on modified relativistic form factors.

Kahane, Sylvian; Moreh, R.; Shahal, O.

1996-10-01

339

Destruction of CO ice and formation of new molecules by irradiation with 28 keV O 6+ ions  

Microsoft Academic Search

The effect of solar wind on cometary ice was studied by using oxygen ions with energy near to that corresponding to their maximum abundance in space for bombarding CO ice. This gas was condensed on a CsI substrate at 14K and irradiated by 28keV 18O6+ ions up to a final fluence of 1.31016cm?2. We have used a methodology in which

A. L. F. de Barros; E. Seperuelo Duarte; L. S. Farenzena; E. F. da Silveira; A. Domaracka; H. Rothard; P. Boduch

2011-01-01

340

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

NASA Astrophysics Data System (ADS)

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

Eisner, Edward; David, Jonathan; Justesen, Perry; Kamenitsa, Dennis; McIntyre, Edward; Rathmell, Robert; Ray, Andrew; Rzeszut, Richard

2012-11-01

341

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

PubMed

At the ionising radiation department of the D.I. Mendeleyev Institute for Metrology, a semiconductor detector was calibrated in the energy range 200-8500 keV using (n,2?) and (n,?) reactions. Separate cylindrical targets (77 mm diameter and 10mm height) were made from mercuric sulphate, sodium chloride and metallic titanium. A (252)Cf spontaneous fission neutron source, placed in 150 mm diameter polyethylene ball, was used to generate thermal neutrons. The optimal target dimensions were determined taking into account the thermal neutron cross-sections and gamma-radiation attenuations in the target materials. The influence of the background radiation induced by neutrons from the walls, floors and ceilings was also taken into account. The shapes of the efficiency curves for point and volume sources in the 200-8500 keV range have been investigated. The experimental results are in good agreement with Monte-Carlo calculations. The emission rate of the 6.13 MeV photons from a (238)Pu-(13)C source was determined with an expanded uncertainty, U(c), of 10% (k=2). PMID:22512978

Tereshchenko, Evgeny E; Moiseev, Nikolay

2012-04-04

342

Absolute bremsstrahlung yields at 135 from 53-keV electrons on gold film targets  

NASA Astrophysics Data System (ADS)

Results are presented for the absolute bremsstrahlung yields at a backward angle of 135 from 53keV electrons on gold targets of thickness ranging from 66to28976?g/cm2 . The target thicknesses range from thin enough for single collision conditions to apply to thick enough for the yield to be dominated by multiple interactions. The results for all thicknesses are found to be in very good agreement with the predictions of PENELOPE, a Monte Carlo program which is based on ordinary bremsstrahlung and does not include any contribution from polarization bremsstrahlung. Absolute doubly differential cross sections are computed for the thinnest targets. The results are compared with two theoretical free atom cross section models, one for ordinary bremsstrahlung only and the second, the stripping approximation, for total bremsstrahlung including a contribution from polarization bremsstrahlung. The results agree with the predictions of ordinary bremsstrahlung for radiated photon energies from 5to53keV and do not agree with the predictions of the stripping approximation. The conclusion, in contrast with recent free gas atom results, is that the absolute yields from solid films are well described by ordinary bremsstrahlung and do not require any additional polarizational bremsstrahlung contribution.

Williams, Scott; Quarles, C. A.

2008-12-01

343

Sputtering of (100) Si by 350 keV Co implantation  

NASA Astrophysics Data System (ADS)

Silicon (100) substrates have been implanted with 350 keV Co to fluences in the range 7.2 1015 to 3.3 1017 Co/cm2 at temperatures near 100 C and 450 C. Rutherford backscattering profiles of the implanted Co were analyzed by the computer code MEASTRI to extract values for the sputtering coefficient, S, of Si by Co at these temperatures. At the lower temperatures S =1.1+/- 0.2 results from the analysis, while at 450 C we obtain S=1.8 +/- 0.2. The value predicted by the Matsunanu/Yamamura formula is S = 1.6. Our results are consistent with those of Nizam and Benazeth-Colombie which show a similar variation in S for 40 keV Ar+ bombardment of (100) Si in the temperature range 50-550 C. This temperature variation is interpreted as due to an altered surface binding energy resulting from surface rearrangement at the higher temperatures.

Brice, D. K.; Barbour, J. C.

1989-04-01

344

Experimental investigation of multiple scattering of 662 keV gamma rays in zinc at 90  

NASA Astrophysics Data System (ADS)

Compton scattering investigations usually examine the case when photon has undergone only one Compton collision in the sample. The probability of a photon being scattered several times may be significant for a target of finite dimensions both in depth and lateral dimensions. The present experiment is undertaken to study the intensity and energy distributions of 662 keV gamma rays multiply scattered from a zinc target of various thicknesses at a scattering angle of 90 with the scattered photons being detected by an HPGe gamma detector. We observe that with an increase in target thickness, the number of multiply scattered photons also increases and saturates at a particular value of the target thickness (saturation depth). This supports the work of Paramesh, L., Venkataramaih, L., Gopala, K., Sanjeevaih, H. [1983. Z-dependence of saturation depth for multiple scattering of 662 keV photons from thick samples. Nucl. Instrum. Methods 206, 327 230]. The double Compton scattered peak is also observed in the experimental spectra, with a position in agreement with the predictions of Fernandez, J.E. [1991. Compton and Rayleigh double scattering of unpolarized radiation. Phys. Rev. A44, 4232 4248] and Barnea, G., Dick. C.E., Ginzburg. A.E., Seltzer. S.M. [1995. A study of multiple scattering background in Compton scatter imaging. NDT E Int. 28. 155 162].

Singh, Gurvinderjit; Singh, Manpreet; Sandhu, B. S.; Singh, Bhajan

2007-05-01

345

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

NASA Astrophysics Data System (ADS)

We report on the realization and operation of a fast ion beam trap of the linear electrostatic type employing liquid helium cooling to reach extremely low blackbody radiation temperature and residual gas density and, hence, long storage times of more than 5 min which are unprecedented for keV ion beams. Inside a beam pipe that can be cooled to temperatures <15 K, with 1.8 K reached in some locations, an ion beam pulse can be stored at kinetic energies of 2-20 keV between two electrostatic mirrors. Along with an overview of the cryogenic trap design, we present a measurement of the residual gas density inside the trap resulting in only 2103 cm-3, which for a room temperature environment corresponds to a pressure in the 10-14 mbar range. The device, called the cryogenic trap for fast ion beams, is now being used to investigate molecules and clusters at low temperatures, but has also served as a design prototype for the cryogenic heavy-ion storage ring currently under construction at the Max-Planck Institute for Nuclear Physics.

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

2010-05-01

346

Phase-contrast imaging and tomography at 60 keV using a conventional x-ray tube source  

SciTech Connect

Phase-contrast imaging at laboratory-based x-ray sources using grating interferometers has been developed over the last few years for x-ray energies of up to 28 keV. Here, we show first phase-contrast projection and tomographic images recorded at significantly higher x-ray energies, produced by an x-ray tube source operated at 100 kV acceleration voltage. We find our measured tomographic phase images in good agreement with tabulated data. The extension of phase-contrast imaging to this significantly higher x-ray energy opens up many applications of the technique in medicine and industrial nondestructive testing.

Donath, Tilman; Bunk, Oliver; Groot, Waldemar; Bednarzik, Martin; Gruenzweig, Christian; David, Christian [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Pfeiffer, Franz [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Ecole Polytechnique Federale de Lausanne, 1015 Lausanne (Switzerland); Hempel, Eckhard; Popescu, Stefan; Hoheisel, Martin [Siemens AG, Healthcare Sector, 91301 Forchheim (Germany)

2009-05-15

347

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

SciTech Connect

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

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

2007-06-13

348

Sterilization of foods with low-energy electrons (``soft-electrons'')  

NASA Astrophysics Data System (ADS)

Electrons with an energy of 300 keV or lower were defined as ``Soft-electrons'', which showed several advantages over conventional irradiation with gamma-rays or high-energy electrons in decontamination of grains and spices. Energies of electrons necessary to reduce microbial loads to levels lower than 10 CFU/g were 60 keV for brown rice, 75 keV for wheat, 100 keV for white pepper, coriander and basil, 130 keV for buckwheat, 160 keV for rough rice, and 210 keV for black pepper. Electrons with such energies did not significantly influence the quality.

Hayashi, Toru; Takahashi, Yoko; Todoriki, Setsuko

1998-06-01

349

Interactions of keV sterile neutrinos with matter  

SciTech Connect

A sterile neutrino with mass of several keV is a well-motivated dark-matter candidate, and it can also explain the observed velocities of pulsars via anisotropic emission of sterile neutrinos from a cooling neutron star. We discuss the interactions of such relic particles with matter and comment on the prospects of future direct detection experiments. A relic sterile neutrino can interact, via sterile-active mixing, with matter fermions by means of electroweak currents, with the final state containing a relativistic active neutrino. The recoil momentum impacted onto a matter fermion is determined by the sterile neutrino mass and is enough to ionize atoms and flip the spins of nuclei. While this suggests a possibility of direct experimental detection, we calculate the rates and show that building a realistic detector of the required size would be a daunting challenge.

Ando, Shin'ichiro [California Institute of Technology, Mail Code 350-17, Pasadena, California 91125 (United States); Kusenko, Alexander [Department of Physics and Astronomy, University of California, Los Angeles, California 90095 (United States); Institute for the Physics and Mathematics of the Universe, University of Tokyo, Kashiwa, Chiba 277-8568 (Japan)

2010-06-01

350

Elastic scattering of 81-keV ? rays  

NASA Astrophysics Data System (ADS)

A high-purity germanium detector was used to determine differential cross sections for the elastic scattering of 81-keV ? rays by aluminum, nickel, tantalum, gold, and lead through angles of 60, 90, 120, and 133. The atomic Rayleigh scattering amplitudes were obtained in the independent-particle approximation by calculations of modified relativistic form factors (MF's), a combination of MF's and angle-independent ``anomalous'' scattering factors (ASF's), and the relativistic second-order S matrix. Most experimental cross sections for gold and lead are slightly smaller than the calculations in the S matrix or the MF-ASF approaches, the differences being larger in the latter case. The calculated cross sections based on MF's are enormously larger than these values. The tantalum data are in good agreement with S-matrix calculations. The data for Al show agreement with the different calculations, which differ by less than about 6%.

Basavaraju, G.; Kane, P. P.; Kissel, Lynn D.; Pratt, R. H.

1994-05-01

351

Electron emission for grazing impact of keV He atoms on an Al(1 1 1) surface  

NASA Astrophysics Data System (ADS)

The energy loss of He atoms with energies E ? 28 keV scattered from Al(1 1 1) under a grazing angle of incidence is recorded in coincidence with the number of electrons emitted in the collision. From our data we deduce the mean energies for emission of a specific number of electrons during impact of the atomic projectiles. We observe that only a fraction of some percent of the energy transferred to metal electrons results in their emission. The mean energy for emission of electrons in head-on binary collisions of He atoms with conduction electrons is estimated from a simple classical model which describes the data fairly well. For higher energies of the projectile motion with respect to the surface normal, i.e. collisions with surface atoms under smaller impact parameters, the mean energy transfer to emitted electrons is enhanced which is attributed to an electron promotion mechanism.

Lederer, S.; Winter, H.; Winter, Hp.

2005-05-01

352

Strength of the Ec.m.=1113 keV resonance in 20Ne(p,?)21Na  

NASA Astrophysics Data System (ADS)

The 20Ne(p,?)21Na reaction is the starting point of the NeNa cycle, which is an important process for the production of intermediate mass elements. The Ec.m.=1113 keV resonance plays an important role in the determination of stellar rates for this reaction since it is used to normalize experimental direct capture yields at lower energies. The commonly accepted strength of this resonance, ??=1.130.07 eV, has been misinterpreted as the strength in the center-of-mass frame when it is actually the strength in the laboratory frame. This has motivated a new measurement of the Ec.m.=1113 keV resonance strength in 20Ne(p,?)21Na using the DRAGON recoil mass spectrometer. The DRAGON result, 0.9720.11 eV, is in good agreement with the accepted value when both are calculated in the same frame of reference.

Christian, G.; Hutcheon, D.; Akers, C.; Connolly, D.; Fallis, J.; Ruiz, C.

2013-09-01

353

Development of a 110-m-mA, 75-keV proton injector for high-current, CW linacs  

SciTech Connect

A dc proton injector is being developed for a 6.7 MeV CW RFQ at Los Alamos. The RFQ input beam requirements are 75 keV energy, 110 mA dc proton current, and 0.20 {pi}mm-mrad rms normalized emittance. The injector has now produced a 75-keV, 117-mA dc proton beam (130 mA total current) with the required emittance. The emittance has been measured after a 2.1 m long two-solenoid beam transport system. The measured emittance can be explained in terms of the ion source emittance and beam transport through the focusing elements. Measured proton fractions are 90-92% of the beam current. Engineering of the accelerating column high-voltage design is being improved to increase the injector reliability. Injector design details and status are presented.

Sherman, J.D.; Bolme, G.O.; Hansborough, L.D. [and others

1996-09-01

354

Imaging Observations of X-Ray Quasi-periodic Oscillations at 3 - 6 keV in the 26 December 2002 Solar Flare  

NASA Astrophysics Data System (ADS)

Quasi-periodic oscillations in soft X-rays (SXR) are not well known due to the instrument limitations, especially the absence of imaging observations of SXR oscillations. We explore the quasi-periodic oscillations of SXR at 3 - 6 keV in a solar flare observed by the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) on 26 December 2002. This was a B8.1 class event and showed three X-ray sources (S1, S2, and S3) at 3 - 6 keV and two sources (S1 and S2) at 12 - 25 keV. The light curves of the total fluxes display a two-minute oscillation at 3 - 6 keV, but not in the energy bands above 8 keV. To investigate imaging observations of the oscillations, we prepared CLEAN images at seven energy bands between 3 keV and 20 keV with an eight-second integration. The light curves of three sources were analyzed after integrating the flux of each source region. We used the Fourier method to decompose each source light curve into rapidly varying and slowly varying components. The rapidly varying components show seven individual peaks which are well fitted with a sine function. Then we used the wavelet method to analyze the periods in the rapidly varying component of each source. The results show that three sources display damped quasi-periodic oscillations with a similar two-minute period. The damped oscillations timescale varies between 2.5 to 6 minutes. Source S1 oscillates with the same phase as S3, but is almost in anti-phase with S2. Analyzing the flaring images in more detail, we found that these oscillation peaks are well consistent with the appearance of S3, which seems to split from or merge with S2 with a period of two minutes. The flare images with a high cadence of one second at 3 - 6 keV show that source S3 appears with a rapid period of 25 seconds. The two-minute oscillation shows the highest spectral power. Source S3 seems to shift its position along the flare loop with a mean speed of 130 km s-1, which is of the same order as the local sound speed. This connection between the oscillation peaks and emission enhancement appears to be an observational constraint on the emission mechanism at 3 - 6 keV.

Ning, Zongjun

2013-10-01

355

Global and local optical model parameterizations. [A > 40, 10 keV-20 MeV  

SciTech Connect

A review is given of global and regional phenomenological neutron optical model parameterizations in the mass region above A = 40 and for neutron energies in the range 10 keV to 20 MeV. The performance of some 11 different neutron parameterizations is investigated for the case of /sup 58/Ni, utilizing Hauser-Feshbach statistical theory calculations of several reactions. A similar, more restricted analysis is made for neutron reactions on /sup 165/Ho, demonstrating the use of two useful approximations in deformed optical model calculations. A regional actinide potential is adapted for use with /sup 165/Ho and is shown to give reasonable results for /sup 165/Ho, /sup 238/U, and /sup 242/Pu. 32 refs., 8 figs., 2 tabs.

Young, P.G.

1985-01-01

356

Dissociation of carbonyl sulfide by 150 keV Ar+ ion impact  

NASA Astrophysics Data System (ADS)

We report on the formation and dissociation of the multiply charged carbonyl sulfide (OCS) molecular ions, OCSq + (where q = 1-4), formed in the collision of neutral OCS molecules with 150 keV Ar+ projectiles, detected using coincidence techniques. From the coincidence map of the fragments we have separated complete two- and three-body dissociation channels resulting in various ionic fragments. Comparing the slope of the coincidence islands with theoretical values, determined from the charge and momentum distribution of the correlated particles, we postulate different decay modes behind each of the fragmentation channels. We also discuss momentum imaging and the kinetic energy release of each of the dissociation channels of OCSq +, which give further information about the momentum balance and the geometry of the precursors in OCS fragmentation.

Jana, M. R.; Ray, B.; Ghosh, P. N.; Safvan, C. P.

2010-11-01

357

Excess Astrophysical Photons from a 0.11 keV Cosmic Axion Background  

NASA Astrophysics Data System (ADS)

Primordial decays of string theory moduli at z1012 naturally generate a dark radiation cosmic axion background with 0.11 keV energies. This cosmic axion background can be detected through axion-photon conversion in astrophysical magnetic fields to give quasithermal excesses in the extreme ultraviolet and soft x-ray bands. Substantial and observable luminosities may be generated even for axion-photon couplings ?10-11GeV-1. We propose that axion-photon conversion may explain the observed excess emission of soft x rays from galaxy clusters, and may also contribute to the diffuse unresolved cosmic x-ray background. We list a number of correlated predictions of the scenario.

Conlon, Joseph P.; Marsh, M. C. David

2013-10-01

358

Excess Astrophysical Photons from a 0.1-1keV Cosmic Axion Background.  

PubMed

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

Conlon, Joseph P; Marsh, M C David

2013-10-11

359

Production of 75-keV, 70-A, 10-s ion beams  

SciTech Connect

High-power long pulse ion sources were fabricated and tested at a prototype injector unit for JT-60. Ion beams of 70 A at an energy of 75 keV were extracted repeatedly for up to 10 s. The heat loadings to each grid were within our design values and each grid turned out to be thermally stable during 10 s pulse. The neutral beam power deposited to the beam target was over 1.43 MW, which corresponds to the design value of the JT-60 neutral beam injector. The e-folding half-width beam divergence angle was about 1.0/sup 0/ at optimum beam current and a proton ratio of about 80% was obtained. It was also confirmed that other beam line components, such as the ion beam dump and the cryopump, were sufficiently reliable.

Akiba, M.; Araki, M.; Horiike, H.

1982-12-01

360

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

SciTech Connect

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

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

2012-07-01

361

A Compound Refractive Lens for 175 keV X-rays  

SciTech Connect

This is to report on the second step in constructing Compound Refractive Lens for focusing 175 keV X-rays for Magnetic Compton Scattering experiment at the BL08W beamline in SPring-8. The lens consists of the metallic plates with small parabolic grooves pressed into it. The first lens for this high energy was made of Fe. Recently we have performed a test on the lens made of Ni and found that it has a focal length of 2.6 m with a size of 9 microns in FWHM. The focused beam is still weaker than the designed value, but it has already achieved two times higher density than unfocused beam.

Andrejczuk, Andrzej; Sakurai, Yoshiharu; Itou, Masayoshi [Japan Synchrotron Radiation Research Institute (JASRI), SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)

2007-01-19

362

Interatomic potentials from rainbow scattering of keV noble gas atoms under axial surface channeling  

NASA Astrophysics Data System (ADS)

For grazing scattering of keV Ne and Ar atoms from a Ag(1 1 1) and a Cu(1 1 1) surface under axial surface channeling conditions we observe well defined peaks in the angular distributions for scattered projectiles. These peaks can be attributed to rainbow-scattering and are closely related to the geometry of potential energy surfaces which can be approximated by the superposition of continuum potentials along strings of atoms in the surface plane. The dependence of rainbow angles on the scattering geometry provides stringent tests on the scattering potentials. From classical trajectory calculations based on universal (ZBL), adjusted Moliere (OConnor and Biersack), and individual interatomic potentials we obtain corresponding rainbow angles for comparison with the experimental data. We find good overall agreement with the experiments for a description of trajectories based on adjusted Moliere and individual potentials, whereas the agreement is poorer for potentials with ZBL screening.

Schller, A.; Wethekam, S.; Mertens, A.; Maass, K.; Winter, H.; Grtner, K.

2005-04-01

363

Proton-carbon monoxide collisions from 10 keV to 14 MeV  

SciTech Connect

We have measured relative cross sections and fragmentation branching ratios for proton-carbon monoxide collisions over a wide velocity range from 0.63 to 23.7 a.u. (i.e., E{sub p} of 10 keV to 14 MeV) using a coincidence time-of-flight technique. For low projectile velocity, where electron capture by the projectile becomes important, this process is separated from ionization by projectile charge-state analysis. Our measurements of CO{sup 2+} production resolve differences between previous measurements, but our multiple-ionization cross-section measurements differ significantly from recent measurements by Siegmann et al. [Phys. Rev. A 66, 052701 (2002)]. The observed kinetic-energy release from dissociating channels varies slowly as the incident proton velocity changes, and in general is not compatible with a simple Coulomb explosion picture.

Wells, E. [J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Department of Physics, Augustana College, Sioux Falls, South Dakota 57197 (United States); Krishnamurthi, Vidhya; Carnes, K.D.; Moore, David; Bloom, Kristana M.; Barnes, B.M.; Ben-Itzhak, I. [J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Johnson, Nora G.; Baxter, Heather D. [Department of Physics, Augustana College, Sioux Falls, South Dakota 57197 (United States); Tawara, H. [J.R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); National Institute for Fusion Sciences, Nagoya 464-01 (Japan)

2005-08-15

364

A 75-keV, 145-mA proton injector  

SciTech Connect

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

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

2001-01-01

365

Efficient production of 100 keV deuterons in deuterium gas puff Z-pinches at 2 MA current  

NASA Astrophysics Data System (ADS)

Deuterium gas puff experiments were carried out on the S-300 Z-pinch at the Kurchatov Institute in Moscow. Gas puffs imploded onto the axis before a current peak at about 100 ns. Fusion neutrons were generated after the gas puff implosion during global expansion of a plasma column. Neutron emission lasted on average 35 5 ns (full width half maximum, FWHM). In the downstream direction (on the Z-pinch axis behind the cathode), a mean neutron energy was 2.6 0.1 MeV. Side-on neutron energy spectra peaked at 2.40 0.05 MeV with about 600 150 keV FWHM. A broad width of side-on neutron spectra implied a high radial component of deuteron velocities. An average kinetic energy of fast deuterons, which produced fusion neutrons, was 150 keV. A peak neutron yield reached a value of 6 1010 on a current level of 1.5 MA. It was by one order higher in comparison with other deuterated loads used on the same current generator. On the basis of experimental observations, we concluded that a total energy of deuterons accelerated to fusion energies was above 1.5 kJ. It is more than 15% of the energy input into a plasma. Therefore gas puff Z-pinches seem to be not only powerful sources of x-ray radiation but also efficient sources of 100 keV deuterons. Such a result is consistent with high neutron yields observed on the Angara Z-pinch and plasma foci with similar currents.

Klir, D.; Kravarik, J.; Kubes, P.; Rezac, K.; Cikhardt, J.; Litseva, E.; Hyhlik, T.; Ananev, S. S.; Bakshaev, Yu L.; Bryzgunov, V. A.; Chernenko, A. S.; Kalinin, Yu G.; Kazakov, E. D.; Korolev, V. D.; Ustroev, G. I.; Zelenin, A. A.; Juha, L.; Krasa, J.; Velyhan, A.; Vysin, L.; Sonsky, J.; Volobuev, I. V.

2010-06-01

366

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

SciTech Connect

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

Tanuma, S. [Materials Analysis Station, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki 305-0047 (Japan); Powell, C. J.; Penn, D. R. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8370 (United States)

2008-03-15

367

Backscattering of {alpha}-Quartz (0 6 10) for 14.4 keV Moessbauer Photons  

SciTech Connect

Backscattering of {alpha}-quartz (0 6 10) was investigated using 14.4 keV 57Fe Moessbauer photons from {alpha}-57Fe2O3 at nuclear resonant scattering beamline BL09XU, SPring-8. The {alpha}-quartz crystal was heated to around 353 K by an oven so that the Bragg angle of {alpha}-quartz 0 6 10 diffraction meats 90 degrees. Energy width of the reflection was measured by changing temperature of the oven. The measured bandwidth is 1.14(33) meV. Backscattering by a {alpha}-quartz crystal can be applied for high-energy-resolution monochromator or analyzer.

Imai, Yasuhiko; Yoda, Yoshitaka; Kikuta, Seishi [Japan Synchrotron Radiation Research Institute, SPring-8, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Zhang Xiaowei [Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization, KEK 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan)

2007-01-19

368

X-ray Absorption Fine Structure Combined with X-ray Fluorescence Spectrometry. Improvement of Spectral Resolution at the Absorption Edges of 9?29 keV  

Microsoft Academic Search

X-ray absorption near-edge structure (XANES) suffers from core-hole lifetime broadening at a higher energy absorption edge, such as Sn K (29 keV, K ) 8.49 eV). To overcome this problem, emitted Sn Kr1 fluorescence from sample was counted using high-energy-resolution fluorescence spectrometer in the XANES measurements. Experimental energy resolution (5.0 eV) was consistent with theoretical values based on the Rowland

Yasuo Izumi; Hiroyasu Nagamori; Fumitaka Kiyotaki; Dilshad Masih; Taketoshi Minato; Eric Roisin; Jean-Pierre Candy; Hajime Tanida; Tomoya Uruga

2005-01-01

369

Cross Section for Excitation of the Fourth Positive Band System in Carbon Monoxide by 20-120 keV Protons  

Microsoft Academic Search

Excitation cross sections for the fourth positive band system in carbon monoxide have been determined from studies of the energy-loss spectra of 20-120-keV protons incident on gaseous CO targets. The energy-loss spectra had an energy resolution of about 2 eV. Prominent peaks in the spectra were observed at 8.5 and 13.8 eV. The first peak is believed to be due

John T. Park; D. R. Schoonover; George W. York

1970-01-01

370

First Results from Fermi Gamma-ray Burst Monitor Earth Occultation Monitoring: Observations of Soft Gamma-ray Sources Above 100 keV  

NASA Astrophysics Data System (ADS)

The NaI and BGO detectors on the Gamma-ray Burst Monitor (GBM) on Fermi are now being used for long-term monitoring of the hard X-ray/low-energy gamma-ray sky. Using the Earth occultation technique as demonstrated previously by the BATSE instrument on the Compton Gamma-Ray Observatory, GBM can be used to produce multiband light curves and spectra for known sources and transient outbursts in the 8 keV to 1 MeV energy range with its NaI detectors and up to 40 MeV with its BGO detectors. Over 85% of the sky is viewed every orbit, and the precession of the Fermi orbit allows the entire sky to be viewed every ~26 days with sensitivity exceeding that of BATSE at energies below ~25 keV and above ~1.5 MeV. We briefly describe the technique and present preliminary results using the NaI detectors after the first two years of observations at energies above 100 keV. Eight sources are detected with a significance greater than 7?: the Crab, Cyg X-1, SWIFT J1753.5-0127, 1E 1740-29, Cen A, GRS 1915+105, and the transient sources XTE J1752-223 and GX 339-4. Two of the sources, the Crab and Cyg X-1, have also been detected above 300 keV.

Case, G. L.; Cherry, M. L.; Wilson-Hodge, C. A.; Camero-Arranz, A.; Rodi, J. C.; Chaplin, V.; Finger, M. H.; Jenke, P.; Beklen, E.; Bhat, P. N.; Briggs, M. S.; Connaughton, V.; Greiner, J.; Kippen, R. M.; Meegan, C. A.; Paciesas, W. S.; Preece, R.; von Kienlin, A.

2011-03-01

371

Testing of typical spacecraft materials in a simulated substorm environment. [1 nA\\/cm² of 2- to 20keV electrons  

Microsoft Academic Search

An investigation to determine spacecraft materials characteristics under charging conditions was conducted at the Lewis Research Center substorm simulation facility. The test specimens were spacecraft paints, silvered Teflon, thermal blankets and solar array segments. The samples, ranging in size from 300 to 1,000 sq cm were exposed to monoenergetic electron energies from 2 to 20 keV at a current density

N. J. Stephens; F. D. Berkopec; J. V. Staskus; R. A. Blech; S. J. Narciso

1976-01-01

372

The g-factor of the 305 keV state of 48V  

Microsoft Academic Search

The g-factor of the 305 keV state of the doubly odd nucleus 48V has been determined by observing the rotation of the 116 keV 305 keV gammagamma-angular correlation in strong external magnetic fields. Liquid sources as well as 48Cr sources embedded in the lattice of metallic copper were used for these measurements. A slight attenuation of the angular correlation was

K. Auerbach; J. Braunsfurth; M. Maier; E. Bodenstedt; H. W. Flender

1967-01-01

373

Waveguide formation in LiTaO 3 and LiB 3O 5 by keV hydrogen ion implantation  

Microsoft Academic Search

Lithium tantalate (LiTaO3) samples were implanted with H+ ions at different energies from 250 to 350 keV using different doses. Lithium triborate (LiB3O5) samples were implanted at 350 keV H+ ions with doses from 11016 to 51016 ions\\/cm2 in increment of 11016 ions\\/cm2 at room temperature. The modes in LiTaO3 and LiB3O5 samples were measured by a model 2010 prism

Ke-Ming Wang; Feng Chen; Hui Hu; Jian-Hua Zhang; Fei Lu; Bo-Rong Shi; Qing-Ming Lu; Chang-Qin Ma

2001-01-01

374

The g-factor of the 184 keV state of 67Zn  

Microsoft Academic Search

The angular correlation of the 209-184 keV gamma-gamma cascade in 67Zn has been measured as W(theta)= 1-(0.222+\\/-0.024)P2(cos theta) +\\/- (0.027 +\\/-1.033) P4(cos theta). For the 184 keV transition we derived the E2\\/M1 mixing parameter delta= +0.41 +\\/-0.06. The half-life of the 184 keV state has been redetermined as T1\\/2 = 1.01+\\/-0.05 ns. The g-factor of the 184 keV state was

R. M. Lieder; M. Fleck; K. Killig; M. Forker; K.-H. Speidel; E. Bodenstedt

1967-01-01

375

Applications of non-periodic multilayer optics for high-resolution x-ray microscopes below 30 keV  

NASA Astrophysics Data System (ADS)

Multilayer mirrors with enhanced bandwidth were developed with special performances for dense plasma diagnostics and mainly for high spatial resolution x-ray imaging. The multilayer coatings are designed to provide broadband x-ray reflectance at low grazing incidence angles. They are deposited onto toroidal mirror substrates. Our research is directed at the development of non-periodic (depth graded) W/Si multilayer specifically designed for use in the 1 to 30 keV photon energy band. First, we present a study for a 5 to 22 keV x-ray spectral window at 0.45 grazing angle. The goal is to obtain a high and constant reflectivity. Second, we have modeled a broadband mirror coating for harder x-rays in the range from 10 to 30 keV, with a non-periodic structure containing 300 W/SiC layers with periods in the range from 0.8 to 4 nm, designed for 0.35 grazing incidence angle.

Troussel, Ph.; Dennetiere, D.; Rousseau, A.; Darbon, S.; Hghj, P.; Hedacq, S.; Krumrey, M.

2012-10-01

376

Applications of non-periodic multilayer optics for high-resolution x-ray microscopes below 30 keV.  

PubMed

Multilayer mirrors with enhanced bandwidth were developed with special performances for dense plasma diagnostics and mainly for high spatial resolution x-ray imaging. The multilayer coatings are designed to provide broadband x-ray reflectance at low grazing incidence angles. They are deposited onto toroidal mirror substrates. Our research is directed at the development of non-periodic (depth graded) W?Si multilayer specifically designed for use in the 1 to 30 keV photon energy band. First, we present a study for a 5 to 22 keV x-ray spectral window at 0.45 grazing angle. The goal is to obtain a high and constant reflectivity. Second, we have modeled a broadband mirror coating for harder x-rays in the range from 10 to 30 keV, with a non-periodic structure containing 300 W?SiC layers with periods in the range from 0.8 to 4 nm, designed for 0.35 grazing incidence angle. PMID:23127039

Troussel, Ph; Dennetiere, D; Rousseau, A; Darbon, S; Hghj, P; Hedacq, S; Krumrey, M

2012-10-01

377

Large-angle elastic scattering of 59.54-keV photons by elements with 12<=Z<=92  

NASA Astrophysics Data System (ADS)

Elastic-scattering cross sections for 59.54-keV photons have been measured at an angle of 121 for 42 elements in the atomic region 12<=Z<=92. The measurements were performed using a 241Am radioisotope as the photon source and a Si (Li) detector. The measured cross sections have been compared with those based on the modified-relativistic form factors (MF's), a combination of the MF's and angle-independent ``anomalous'' scattering factors (MF+ASF), and the relativistic second-order S-matrix calculations. The MF cross sections are found to be enormously higher for the elements with K-shell binding energy (EK) close to the incident photon energy (Einc) of 59.54 keV. The S matrix and MF+ASF cross sections, in general, represent the trend of the measured data over the whole atomic region under investigation. These theoretical cross sections are in good agreement with the measured data for the elements with 12<=Z<=26 and, thereafter, deviate with increasing Z. The S matrix and MF+ASF values are, on the average, higher by 17%, and 24%, respectively, for the elements with 39<=Z<=67 and by 10% and 19%, respectively, for the elements with 70<=Z<=92. In case of 68Er, having a K-shell binding energy 2.1 keV lower than the incident photon energy, the MF+ASF value shows good agreement with the measured one, and the S matrix value is lower by 12%.

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

1998-06-01

378

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

SciTech Connect

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

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

2011-10-15

379

Destruction of 18F via 18F(p,?)15O burning through the Ec.m.=665 keV resonance  

NASA Astrophysics Data System (ADS)

Knowledge of the astrophysical rate of the 18F(p,?)15O reaction is important for understanding the ?-ray emission expected from novae and heavy-element production in x-ray bursts. The rate of this reaction is dominated at temperatures above ~0.4 GK by a resonance near 7.08 MeV excitation energy in 19Ne. The 18F(p,?)15O rate has been uncertain in part because of disagreements among previous measurements concerning the resonance strength and excitation energy of this state. To resolve these uncertainties, we have made simultaneous measurements of the 1H(18F,p)18F and 1H(18F,?)15O excitation functions using a radioactive 18F beam at the ORNL Holifield Radioactive Ion Beam Facility. A simultaneous fit of the data sets has been performed, and the best fit was obtained with a center-of-mass resonance energy of 664.7+/-1.6 keV (Ex=7076+/-2 keV), a total width of 39.0+/-1.6 keV, a proton branching ratio of ?p/?=0.39+/-0.02, and a resonance strength of ??=6.2+/-0.3 keV.

Bardayan, D. W.; Blackmon, J. C.; Bradfield-Smith, W.; Brune, C. R.; Champagne, A. E.; Davinson, T.; Johnson, B. A.; Kozub, R. L.; Lee, C. S.; Lewis, R.; Parker, P. D.; Shotter, A. C.; Smith, M. S.; Visser, D. W.; Woods, P. J.

2001-06-01

380

Do the O2 Schumann-Runge Bands Participate in keV Collision-Induced Dissociation Experiments?  

NASA Astrophysics Data System (ADS)

In high-energy (keV) CID experiments, oxygen has the unique ability to enhance specific ion fragmentation pathways that lie within a relatively narrow band of activation energy. It has been previously proposed that this oxygen-enhanced dissociation phenomenon is due to the participation of the {{O}_{{2}}}{B}{ ^{{3}}}{?_{{u}}}^{ + } - {X}{ ^{{3}}}{?_{{g}}}^{ - } (Schumann-Runge) system in the collision complex. During the collision, oxygen is first excited to its {B}{ ^{{3}}}{?_{{u}}}^{ + } state before it returns this energy to the projectile ion. This energy drives the nonstatistical dissociation of the projectile provided there is an energetically accessible pathway in resonance with the absorbed radiation. To probe the validity of this hypothesis, a modified VG-ZAB mass spectrometer was used to observe the photon emissions from keV collisions of a selection of projectile ions with O2 target gas. By studying the resulting collision-induced emission (CIE) spectra, a second potential mechanism came to light, one that involves the near-isoenergetic O2 +. A 2?u?X 2 ?g state transition.

Lin, Yawei; Mayer, Paul M.

2011-01-01

381

State-resolved study of keV sputtered neutral atoms by resonance ionization spectroscopy  

SciTech Connect

We have performed simultaneous measurements of energy-, and angle-resolved distributions of Ni atoms desorbed from a single crystal Ni{l_brace}100{r_brace} surface bombarded by 5 keV Ar{sup +} ions. Ground state and six low-lying excited states from the a{sup 3}FJ (J=4,3,2) and a{sup 3}DJ (J=3,2,1) manifolds as well as a{sup 1}D2 have been investigated along different azimuths. Both a{sup 3}FJ and a{sup 1}D2 states have closed shell electronic structure, 3d{sup 8}4s{sup 2}, while the a{sup 3}DJ states are open shell electronic states, 3d{sup 9}4s{sup 1}. Angle-integrated energy distributions demonstrate a strong dependence on the electronic structure while the magnitude of the excitation energy does not significantly alter the results. This is the first conclusive evidence that electronic structure rather than excitation energy is the primary factor in determining kinetic energy distributions of sputtered neutral species. Population distribution among the seven electronic states are obtained through two sets of measurements performed on two experimental apparati: one measures the energy- and angle-integrated resonance ionization signal intensities of the sputtered Ni; the other measures the resonance ionization signal intensities of thermally evaporated Ni atoms with a known heating temperature. The experiment results show that the population distribution is very different from Boltzman-type distribution with a{sup 3}D3 and a{sup 3}D2 states more intensely populated. The work also illustrates the power of RIS to perform quantum state specific measurements on fast moving atoms.

He Chun; Postawa, Z.; Rosencrance, S.; Chatterjee, R.; Garrison, B. J.; Winograd, N. [Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

1995-04-01

382

Determination of the dependence of HPGe virtual point detector location on source dimensions in 60 keV-2 MeV range using Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

The virtual point detector (VPD) concept for an HPGe detector with 55% relative efficiency was confirmed for bulky sources having different diameters and heights. After reproducing experimental data, Monte Carlo simulation was used to investigate the dependence of VPD location on photon energy for various source diameters and heights in the energy range from 60 keV to 2 MeV. The simulations were confirmed using a soil reference source prepared by International Atomic Energy Agency (IAEA). It was seen that increasing photon energy makes significant changes in VPD location up to 600 keV. It was observed that VPD locations increase with increasing source diameter and height. It was also seen that VPD locations were approximately linearly dependent on source diameters and heights.

elik, N.

2012-08-01

383

The appearance and disappearance of the 17keV neutrino  

Microsoft Academic Search

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 \\

Allan Franklin

1995-01-01

384

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

PubMed

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

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

2007-01-12

385

New Approach for Measuring the (n,?) Cross Section of a Nucleus by a Few keV Neutron  

NASA Astrophysics Data System (ADS)

We have for the first time determined with high precision the energy spectrum of low-energy neutrons (En<10 keV) which are produced in the 7Li( p,n)7Be reaction, by detecting ?-rays of the 197Au(n,?)198Au reaction whose cross section is known. An anti-Compton NaI(Tl) spectrometer played an essential role in detecting the ?-rays with a good signal to noise ratio by discriminating large background due to thermalized neutrons in the measurement room. The low energy neutrons thus derived were successfully used to measure the 62Ni(n,?)63Ni reaction cross section. The present low energy neutrons could be extensively used for cross section measurements for neutron capture reactions and elastic scatterings from nuclei of nuclear astrophysical interests.

Segawa, Mariko; Tomyo, Atsushi; Nagai, Yasuki; Temma, Yasuyuki; Masaki, Tomohiro; Shima, Tatsushi; Nishiyama, Jun; Ohsaki, Toshiro; Igashira, Masayuki

2005-11-01

386

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

NASA Astrophysics Data System (ADS)

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

Imazono, Takashi; Koike, Masato; Kawachi, Tetsuya; Hasegawa, Noboru; Koeda, Masaru; Nagano, Tetsuya; Sasai, Hiroyuki; Oue, Yuki; Yonezawa, Zeno; Kuramoto, Satoshi; Terauchi, Masami; Takahashi, Hideyuki; Handa, Nobuo; Murano, Takanori

2012-07-01

387

Determination of random and aligned stopping powers for 80300 keV protons in silicon by back-scattering measurements  

Microsoft Academic Search

The proton stopping powers random and aligned along the channels [1101, [100], and [111] of silicon single crystals, in the energy range 80300 keV, have been determined by measuring the energy of the protons back-scattered by a damaged layer previously produced by ion bombardment. The depth of this reference damage peak has been measured by using the technique introduced by

F. Cembali; F. Zignani

1977-01-01

388

Analysis of 2H(vec{d}, p)3H Reaction at 30-90 KeV by Four-Body Faddeev-Yakubovsky Equation  

NASA Astrophysics Data System (ADS)

Low-energy 2H(vec{d}, p)3H reactions are investigated by the four-body Faddeev-Yakubovsky equations. Cross sections and tensor analyzing powers are calculated at 30-90 keV energies. The PEST-1 potentials are used for nucleon-nucleon interactions. The [2 + 2] and [3 + 1] subamplitudes are treated by the Hilbert-Schmidt expansions. Numerical results give qualitative explanation of experimental data.

Uzu, E.; Oryu, S.; Tanifuji, M.

1993-10-01

389

Measurements of keV neutron capture cross sections with a 4. pi. barium fluoride detector: Examples of sup 93 Nb, sup 103 Rh, and sup 181 Ta  

Microsoft Academic Search

A new experimental method has been implemented for precise measurements of neutron capture cross sections in the energy range from 3 to 200 keV. Neutrons are produced via the ⁷Li({ital p},{ital n})⁷Be reaction using a pulsed 3-MV Van de Graaff accelerator. The neutron energy is determined by the time-of-flight (TOF) technique using flight paths of less than 1 m. Capture

K. Wisshak; F. Voss; F. Kaeppeler; G. Reffo

1990-01-01

390

Detection of 10-20 keV H+, He+ ions and electrons by planar oxide passivated and ion implanted silicon diodes  

Microsoft Academic Search

A low noise UV-enhanced silicon photodiode has been modified into a low energy particle detector by removing the antireflection oxide layer. The electronic noise of a 100 mm2 device and a conventional charge sensitive preamplifier has been measured to 2.3 keV FWHM at room temperature operation. The response of this detector to low energy particles has been investigated. Electrons with

G. A. Johansen; J. Stadsnes; F. Sraas; T. E. Hansen

1991-01-01

391

Differences in the neutralization of 2. 4--10 keV Ne[sup +] scattered from the Cu and Au atoms of an alloy surface  

Microsoft Academic Search

The neutralization behavior of low-energy Ne[sup +] ions scattered from a compositionally ordered Cu[sub 3]Au(100) surface has been studied over a range of incident energy [ital E][sub 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 [ital E][sub 0

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

1993-01-01

392

Absolute Cross Sections for Excitation of Neon by Impact of 20-180keV H+, H+2, and He+  

Microsoft Academic Search

The technique of heavy-ion energy-loss spectrometry has been used to measure excitation cross sections for the (2p5)3s and (2p5)3p electronic configurations of neon by impact of heavy ions upon ground-state neon. The incident particles used were H+, H+2, and He+ at impact energies from 20 to 180 keV. The results are compared with previous optical measurements of the emission cross

G. W. York; J. T. Park; V. Pol; D. H. Crandall

1972-01-01

393

230 nm Resolution 10 keV X-Ray Imaging Transmission Microscope with Parallel Beam Illumination  

NASA Astrophysics Data System (ADS)

The spatial resolution of an imaging transmission hard X-ray microscope has been greatly enhanced by the use of an X-ray phase zone plate with a numerical aperture five times larger than the previous one [Y. Kagoshima, T. Ibuki, K. Takai, Y. Yokoyama, N. Miyamoto, Y. Tsusaka and J. Matsui: Jpn. J. Appl. Phys. 39 (2000) L433]. An experiment was carried out at the photon energy of 10 keV to evaluate the performance of the microscope. It was confirmed that the spatial resolution was 230 nm and that a line-and-space pattern as fine as 100 nm could be imaged.

Kagoshima, Yasushi; Ibuki, Takashi; Yokoyama, Yoshiyuki; Takai, Kengo; Tsusaka, Yoshiyuki; Matsui, Junji

2002-01-01

394

The MPE X-ray test facility PANTER: Calibration of hard X-ray (1550 kev) optics  

Microsoft Academic Search

The Max-Planck-Institut fr extraterrestrische Physik (MPE) in Garching, Germany, uses its large X-ray beam line facility\\u000a PANTER for testing X-ray astronomical instrumentation. A number of telescopes, gratings, filters, and detectors, e.g. for\\u000a astronomical satellite missions like Exosat, ROSAT, Chandra (LETG), BeppoSAX, SOHO (CDS), XMM-Newton, ABRIXAS, Swift (XRT), have been successfully calibrated in the soft X-ray energy range (<15keV). Moreover, measurements

M. J. Freyberg; H. Bruninger; W. Burkert; G. D. Hartner; O. Citterio; F. Mazzoleni; G. Pareschi; D. Spiga; S. Romaine; P. Gorenstein; B. D. Ramsey

395

M Sub-Shell Cross Sections For 75-300 keV Proton Impact On W, Pt And Pb  

SciTech Connect

M sub-shell x-ray production cross sections from 75-300 keV proton bombardment of thick elemental targets of W, Pt, and Pb were measured and compared with ECPSSR and relativistic RPWBA-BC cross sections using different data bases of fluorescence yields, Coster-Kronig factors, and x-ray transition rates. With a few exceptions, the differences between the various data base comparisons were not significant. For different sub-shells, either ECPSSR or RPWBA-BC compared better with the measurements. In all cases, agreement with theory improved as the collision energy increased.

Cipolla, Sam J. [Physics Department, Creighton University, Omaha, NE 68178 (United States)

2011-06-01

396

Determination of HPGe detector response using MCNP5 for 20-150 keV X-rays.  

PubMed

The Monte Carlo method was used to calculate the efficiency, escape and Compton curves of a planar high-purity germanium detector (HPGe) in the 20-150 keV energy. These curves were used for the determination of photons spectra produced by an X-ray machine in order to allow a precise characterization of photon beams applied to medical diagnosis. The detector was modeled with the MCNP5 computer code and validated by comparison with experimental data. The air kerma calculated after the spectra stripping was compared with ionization chamber measurements. PMID:16427294

Salgado, Csar Marques; Conti, Claudio C; Becker, Paulo H B

2006-01-19

397

Multiple ionization of diatomic molecules in collisions with 50-300-keV hydrogen and helium ions  

SciTech Connect

Measurements of relative multiple ionization cross sections have been performed for 50-300-keV H{sup +}, D{sup +}, and He{sup +} impact on N{sub 2}, O{sub 2}, CO, and NO molecules. Fragment ions with total charges up to Q=q{sub 1}+q{sub 2}=5 have been detected in coincidence using a position- and time-sensitive detector. Dependence of the cross section on the molecular orientation with respect to the ion beam is observed for all targets. The experimental data are compared with theoretical calculations based on the statistical energy deposition model.

Siegmann, B.; Werner, U.; Kabachnik, N.M.; Lutz, H.O. [Fakultaet fuer Physik, Universitaet Bielefeld, D-33615 Bielefeld (Germany); Kaliman, Z. [Faculty of Philosophy, University of Rijeka, 51000 Rijeka (Croatia); Roller-Lutz, Z. [Institute of Physics, Faculty of Medicine, University of Rijeka, 51000 Rijeka (Croatia)

2002-11-01

398

Elastic scattering of 22.1-keV photons by elements in the atomic region 12<=Z<=92  

NASA Astrophysics Data System (ADS)

Differential cross sections for the elastic scattering of 22.1-keV photons by 30 elements in the atomic region 12<=Z<=92 have been measured at an angle of 117. The measurements were performed under vacuum using Si(Li) detector and 109Cd radioisotope as photon source. The intensity of incident photons, detector efficiency, and other geometrical factors was determined by measuring the K x-ray yields from targets of various elements with 30<=Z<=52 excited by photons from 109Cd and 241Am radioactive sources and from the knowledge of K x-ray fluorescence cross sections. The present measured elastic scattering cross sections have been compared with those obtained in the independent-particle approximation through calculations of modified-relativistic form factors (MF's), a combination of MF"s and angle-independent 'anomalous' scattering factors (ASF's), and the relativistic second-order S matrix. The MF values are found to be enormously larger than the measured ones in case of elements with K-shell or L1-subshell binding energy in the vicinity of 22.1-keV incident photon energy, and exhibit general agreement for other elements. The MF values in combination with ASF's and the S-matrix values are found to be on an average higher by 9% and 12%, respectively, than the measured values. These deviations increase up to 20% in case of elements with K-shell or L1-subshell binding energy just below the incident photon energy, and further decrease to ~5% in case of elements with K-shell binding energy above the incident photon energy. The measured values for Al and Mg having electron binding energies far away from the incident photon energy show good agreement with different calculations.

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

1997-05-01

399

Silicon photodiode characterization from 1 eV to 10 keV  

SciTech Connect

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

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

1997-10-01

400

Experimental Study of the 91Zr(n,gamma) Reaction Up to 26 keV  

SciTech Connect

The neutron capture cross sections of the Zr isotopes are relevant to studies in nuclear structure, nuclear astrophysics, and nuclear technology. The valence neutron of {sup 91}Zr with respect to the neutron magic nucleus {sup 90}Zr has interesting implications for the statistical analysis in the proximity of shell closures. In stellar nucleosynthesis, the Zr isotopes are important for the s-process reaction flow between the Fe seeds and the heavier isotopes. Because of its relatively small (n,{gamma}) cross sections, Zr represents also an interesting structural material for nuclear reactors. For the same reason, these cross sections are difficult to measure and reliable data are sparse. Therefore, the (n,{gamma}) cross sections of the Zr isotopes have been remeasured at the CERN n{_}TOF facility. Thanks to its high instantaneous flux, good energy resolution, and low background, this facility is particularly suited for the determination of small, resonance-dominated cross sections. In this work, results for the {sup 91}Zr(n,){sup 92}Zr reaction are reported in the neutron energy range from thermal to 26 keV. In this region, accurate data of 157 resonances could be obtained, 33 of these resonances are not present in the main databases and/or were observed for the first time.

Tagliente, G. [Instituto Nazionale di Fisica Nucleare, Bari, Italy; Koehler, Paul Edward [ORNL

2009-01-01

401

Experimental study of the Zr91(n,?) reaction up to 26 keV  

NASA Astrophysics Data System (ADS)

The neutron capture cross sections of the Zr isotopes are relevant to studies in nuclear structure, nuclear astrophysics, and nuclear technology. The valence neutron of Zr91 with respect to the neutron magic nucleus Zr90 has interesting implications for the statistical analysis in the proximity of shell closures. In stellar nucleosynthesis, the Zr isotopes are important for the s-process reaction flow between the Fe seeds and the heavier isotopes. Because of its relatively small (n,?) cross sections, Zr represents also an interesting structural material for nuclear reactors. For the same reason, these cross sections are difficult to measure and reliable data are sparse. Therefore, the (n,?) cross sections of the Zr isotopes have been remeasured at the CERN n_TOF facility. Thanks to its high instantaneous flux, good energy resolution, and low background, this facility is particularly suited for the determination of small, resonance-dominated cross sections. In this work, results for the Zr91(n,?)Zr92 reaction are reported in the neutron energy range from thermal to 26 keV. In this region, accurate data of 157 resonances could be obtained, 33 of these resonances are not present in the main databases and/or were observed for the first time.

Tagliente, G.; Milazzo, P. M.; Fujii, K.; Aerts, G.; Abbondanno, U.; lvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Be?v?, F.; Belloni, F.; Berthoumieux, E.; Calvio, F.; Calviani, M.; Cano-Ott, D.; Capote, R.; Carrapio, C.; Cennini, P.; Chepel, V.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Furman, W.; Goncalves, I.; Gonzalez-Romero, E.; Gramegna, F.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Jericha, E.; Kppeler, F.; Kadi, Y.; Karadimos, D.; Karamanis, D.; Kerveno, M.; Koehler, P.; Kossionides, E.; Krti?ka, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marrone, S.; Martnez, T.; Massimi, C.; Mastinu, P.; Mengoni, A.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Pigni, M. T.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Praena-Rodriguez, J.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Santos, C.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Terlizzi, R.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wiescher, M.; Wisshak, K.

2008-10-01

402

Production of ^13N Using a 400keV Van de Graaff Positive Ion Accelerator  

NASA Astrophysics Data System (ADS)

A target system has been developed to study the production and extraction of ^13N, a short-lived radioisotope of nitrogen (t1/2 9.6 minutes), formed via the ^12C(d,n)^13N reaction. The target is comprised of a graphite rod positioned in a custom-built target chamber where it is irradiated by a deuteron beam. Post irradiation, the target is flushed with H2 or CO2 gas, and heated via a large applied current producing ^13NH3 or HC^13N and ^13NO2 respectively. Radiolabeled ^13N compounds are used for physiological imaging using Positron Emission Tomography (PET). The production system used the 400keV Van de Graaff Positive Ion Accelerator housed in the Applied Nuclear Science Lab at Minnesota State University, Mankato. While this energy, slightly above threshold, is too low to make sufficient amounts of ^13N for imaging work, the system and procedure can be implemented on higher energy machines. Preliminary system results will be presented as well as accelerator calibration and reaction data.

Prokop, Christopher; Clymer, John; Compton, Nicholas; Dam, Henry; Hanson, Adam; Pautzke, Justen; Roberts, Andrew

2011-04-01

403

High-efficiency multilevel zone plates for keV X-rays  

NASA Astrophysics Data System (ADS)

The development of high brilliance X-ray sources coupled with advances in manufacturing technologies has led to significant improvements in submicrometre probes for spectroscopy, diffraction and imaging applications. The generation of a small beam spot size is commonly based on three principles: total reflection (as used in optical elements involving mirrors or capillaries), refraction (such as in refractive lenses) and diffraction. The latter effect is employed in Bragg-Fresnel or Soret lenses, commonly known as Fresnel zone plate lenses. These lenses currently give the best spatial resolution, but are traditionally limited to rather soft X-rays-at high energies, their use is still limited by their efficiency. Here we report the fabrication of high-efficiency, high-contrast gold and nickel multistep (quaternary) Fresnel zone plates using electron beam lithography. We achieve a maximum efficiency of 55% for the nickel plate at 7keV. In addition to their high efficiency, the lenses offer the advantages of low background signal and effective reduction of unwanted diffraction orders. We anticipate that these lenses should have a significant impact on techniques such as microscopy, micro-fluorescence and micro-diffraction, which require medium resolution (500-100nm) and high flux at fixed energies.

di Fabrizio, E.; Romanato, F.; Gentili, M.; Cabrini, S.; Kaulich, B.; Susini, J.; Barrett, R.

1999-10-01

404

INTEGRAL observations of Scorpius X-1: evidence for Comptonization up to 200 keV  

NASA Astrophysics Data System (ADS)

We have analyzed a long-term database for Sco X-1 obtained with the telescope IBIS onboard the INTEGRAL satellite in order to study the hard X-ray behavior of Sco X-1 from 20 up to 200 keV. Besides the data used for producing of the INTEGRAL catalog of sources, this is the longest (412 ks) database of IBIS on Sco X-1 up to date. The production of hard X-ray tails in low-mass X-ray binaries is still a matter of debate. Since most of the fits to the high-energy part of the spectra are done with powerlaw models, the physical mechanism for the hard X-ray tail production is unclear. The purpose of this study is to better constrain those possible mechanisms. Our main result shows a strong correlation between the fluxes in the thermal and nonthermal part of Sco X-1 spectra. We, thus, suggest that comptonization of lower energy photons is the mechanism for producing hard X-ray tails in Sco X-1.

Maiolino, T.; D'Amico, F.; Braga, J.

2013-03-01

405

LUCIA - a new 1-7 keV {mu}-XAS Beamline  

SciTech Connect

LURE-SOLEIL (France) and the Swiss Light Source (SLS) are building together a new micro focused beamline for micro x-ray absorption spectroscopy and micro imaging. This line is designed to deliver a photon flux of the order of 1012 ph/sec on a 1 x 1 {mu}m spot within the energy domain of 0.8 to 7 keV. This beam line is being installed on the X07M straight section of SLS. The source is an APPLE II undulator with a period of 54 mm. The main advantage of this device lies in the delivery of any degree of polarization, linear or circular, over the whole energy range, without the need of a sample-position change. The monochromator will be a fixed exit double crystal equipped with 5 sets of crystals, thanks to the very narrow photon beam from the undulator ( Beryl, KTP, YB66, InSb(111), Si(111) ). The optics includes a first horizontal focusing mirror (spherical), which produces an intermediate source for the horizontal mirror of a Kirkpatrick-Baez (KB) system. The vertical mirror of the KB directly images the source. Finally, a low-pass double mirror filter insures a proper harmonic rejection.

Janousch, M.; Schmidt, Th.; Wetter, R.; Grolimund, G.; Scheidegger, A.M. [Paul Scherrer Institute (PSI), CH-5232 Villigen PSI (Switzerland); Flank, A.-M.; Lagarde, P.; Cauchon, G.; Bac, S. [LURE, Bat 209d, Centre Universitaire Paris-Sud, BP 34, 91898 Orsay Cedex (France); Dubuisson, J.M. [Synchrotron SOLEIL, L'Orme de Merisiers, Saint-Aubin, BP 48, 91192 Gif-sur-Yvette Cedex (France)

2004-05-12

406

MULTI-KEV X-RAY YIELDS FROM HIGH-Z GAS TARGETS FIELDED AT OMEGA  

SciTech Connect

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

Kane, J O; Fournier, K B; May, M J; Colvin, J D; Thomas, C A; Marrs, R E; Compton, S M; Moody, J D; Bond, E J; Davis, J F

2010-11-04

407

H- ion source development for the FNAL 750keV injector upgrade  

NASA Astrophysics Data System (ADS)

The new FNAL 750keV injector upgrade for the replacement of the 40 year old Fermi National Laboratory (FNAL) Cockcroft-Walton accelerators with a new ion source and 200MHz Radio Frequency Quadrupole (RFQ), Low Energy Beam Transport (LEBT) and Medium Energy Beam Transport (MEBT) [1], has been built and is now being tested prior to installation during the 2012 shutdown. The new H- ion source is a round aperture magnetron which was developed at Brookhaven National Lab (BNL) by Jim Alessi[2]. Operational experience from BNL has shown that this type of source is more reliable with a longer lifetime (on the order of 6 to 9 months) due to better power efficiency. With a similar duty factor to BNL, we expect to have a comparable lifetime between source changes. The new source design reliably produces 90mA of H- beam current at 15Hz rep-rate, 250?s pulse width, and a duty factor of 0.38%. The measured emittances at the end of the LEBT are horizontally ?H = 0.21? mm* mrad and vertically ?V = 0.17? mm* mrad. With 35kV extraction the power efficiency is 60mA/kW. The source design, along with data from a test stand and the LEBT, will be presented in this paper.

Bollinger, D. S.

2013-02-01

408

Global 30-240 keV proton precipitation in the 17-18 April 2002 geomagnetic storms: 1. Patterns  

NASA Astrophysics Data System (ADS)

Global 30-240 keV proton precipitation patterns during the 17-18 April 2002 magnetic storm events were generated using newly developed 3-hour data products of the medium energy proton and electron detector (MEPED) on board the NOAA-15 and -16 satellites. The observational data set was sorted in 1-degree corrected magnetic latitude (CML) and 8-min magnetic local time (MLT) bins. To achieve global coverage, the missing MLT data were filled by interpolation techniques in each 1-degree CML interval. The resulting global 30-240 keV proton precipitation maps, available on a 3-hour cadence, provide new information on the development and variability in the structure of incident high-energy protons on a timescale commensurate with the growth and decay of the plasma sheet and ring current. The change of energetic proton precipitation patterns in the April 2002 storms is quantified in terms of three aspects: hemispheric integrated total particle energy input, midnight proton oval equatorward boundary, and position of proton precipitation peak. In a general sense, as magnetospheric activity intensified, the midnight equatorward boundary tended to move to the lower latitude, while the precipitation peak moved equatorward and westward away from midnight, in agreement with ring current motion. It is well illustrated that energetic proton precipitation patterns can serve as a valuable diagnostic tool for investigating the inner magnetospheric activity.

Fang, Xiaohua; Liemohn, Michael W.; Kozyra, Janet U.; Evans, David S.; Dejong, Anna D.; Emery, Barbara A.

2007-05-01

409

3-10 keV Xe+ ion beam machining of ultra low thermal expansion glasses for EUVL projection optics: Evaluation of surface roughness  

NASA Astrophysics Data System (ADS)

In order to obtain surface figure error of 0.15 nm rms and surface roughness (Rrms) of 0.12 nm rms for aspherical substrates in EUVL tools, ion beam figuring may be adopted to final surface figure error correction of aspherical substrates. During figure error correction, machined surface of the substrate becomes rougher than the pre-finished one. Therefore, we investigated the machined depth and ion energy dependences of Rrms (measured by an AFM) of substrates machined by 3-10 keV Xe+ ion beam, and compared them with the results obtained for Ar+ ion beam. Result shows that the R of CLEARCERAM-Z, Zerodur and ULE substrates machined to the depth of 50 nm by 3-10 keV Xe+ ion beam at the normal ion incidence angle become approximately 0.25, 0.28 and 0.15 nm rms, respectively. Those values are larger than the pre-finished substrates (0.07-0.09 nm rms), but smaller than that (0.60 nm rms for CLEARCERAM-Z, 0.61 nm rms for Zerodur and 0.18 nm rms for ULE) of the substrates machined by Ar+ ion beam. Moreover, the R merely increase with increasing ion energy. The R of the ULE substrate machined by 3-10 keV Xe+ ion beam rapidly increase with increasing machined depth, then saturate at machined depth of 10-50 nm. The saturated values of the R are 0.12 and 0.15 nm rms for 3 and 10 keV Xe+ ion beam respectively. We suggest that the 3 keV Xe+ ion beam machining can be applicable for final shape correction of ULE substrates for EUVL projection optics in association with considering further ultra smoothing process such as Si deposition or low energy ion beam smoothing.

Morikawa, K.; Kamijo, K.; Morijiri, K.; Pahlovy, S. A.; Aikawa, N.; Miyamoto, I.

2012-02-01

410

Single-photon ionization of helium from 4.5 to 12 keV by Compton scattering and the photoelectric effect  

NASA Astrophysics Data System (ADS)

We have measured the ratio of the cross sections for double-to-single ionization in helium for several monoenergetic photon energies between 4.5 and 12 keV using time-of-flight ion charge state spectroscopy. In this energy range, both the photoelectric effect and inelastic (Compton) scattering contribute significantly to the total cross section. The ionization states caused by Compton scattering were distinguished from those caused by the photoelectric effect by the different recoil energies of the helium ion associated with the two processes. The ratios of the double-to-single ionization cross sections of helium for the photoelectric effect (Rp) and for Compton scattering (Rc) are given, and compared with previous measurements and theoretical calculations. The measured value for Rc at 12 keV is (1.21+/-0.27)%, which agrees well with the theoretical calculations of Andersson and Burgdrfer [Phys. Rev. A 50, R2810 (1994)].

Morgan, D. V.; Bartlett, R. J.

1999-05-01

411

Evidence for a 17 keV level in /sup 168/Tm  

SciTech Connect

The spectrum of neutrons following the /sup 169/Tm(..gamma..,n)/sup 168/Tm reaction induced by 8999 keV neutron capture gamma rays has been investigated with a /sup 3/He spectrometer. The data obtained, when combined with a Q value of 8032.5 +- 2.3 keV quoted in the most recent atomic mass table, provide unambiguous evidence for the existence of a level at 17 keV. This level had not been clearly established in charged-particle reaction studies.

Tsai, J.; Prestwich, W.V.; Kennett, T.J.

1986-11-01

412

The gyromagnetic ratio of the 589 keV 3\\/2 ? state of 117 In  

Microsoft Academic Search

Theg-factor of the 589 keV state of117In has been determined by a measurement of the rotation of the 1,303273 keV? ? directional correlation in an external magnetic field of 9.55(1) T. The result,g3\\/2(589 keV)=+0.068(39), contradicts the usual interpretation of the state as the 2p3\\/2 single proton hole configuration for which the Schmidt value isg3\\/2-(Schmidt)=+2.53. It favours the interpretation as the

A. Alzner; E. Bodenstedt; B. Gemnden; H. Reif

1985-01-01

413

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

NASA Astrophysics Data System (ADS)

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 [Drr 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.

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

2012-07-01

414

High Resolution, 20-100 keV X-ray Backlighters for ICF and HEDS Experiments  

NASA Astrophysics Data System (ADS)

We are studying the feasibility of high resolution radiography using short pulse high intensity lasers. Specifically we wish to better characterize and optimize the Kalpha X-ray production and brightness created by relativistic electron plasma interactions in the target material. We plan to utilize this Kalpha source as a backlighter to image various stages of implosions and planar driven high Z materials. Particularly interesting are the production of Kalpha's in the range 20 100 keV. In order to assess in detail the characteristics of such high energy X-ray backlighters, we are performing experiments using the 10 J, 100 fs JanUSP laser at LLNL. We will measure Kalpha source generation efficiency as function of laser beam parameters such as pulse duration, spot size and laser beam energy. We are also developing a high resolution hard X-ray imaging detector system. This paper will present initial results from the JanUSP experiments. Reference:D.K. Bradley, O.L. Landen, A.B. Bullock, S.G. Glendinning, and R.E. Turner, "Efficient, High Spatial-Temporal Resolution, 1-100 keV X-ray Radiography," Opt. Lett. 27(2002) 134.

Park, Hye-Sook; Koch, J. A.; Landen, O. L.; Phillips, T. W.; Schmid, G. J.

2002-11-01

415

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

NASA Astrophysics Data System (ADS)

We report measurements of the transmission of 1 - 6-keV energy positrons through films of Al, Cu, and Si up to 3000 thick. When the thickness is expressed in terms of mass per unit area, the transmission of Cu and Al is found to be the same within 10%. Within a 20% precision we observe no effect having to do with the crystallinity of the materials. The median penetration depth of positrons in Al and Cu is found to vary with the energy E as En, with n=1.60+0.15-0.08and1.43+0.07-0.11, respectively. Our measured median penetration depths are significantly less than one would have expected from the calculation of Nieminen and Oliva [R. M. Nieminen and J. Oliva,

Phys. Rev. B 22, 2226 (1980)
] which seems to indicate the importance of large-angle scattering effects. Our measurements can be combined with independent measurements of the energy dependence of the yield of positronium at a surface [K. G. Lynn,
Phys. Rev. Lett. 44, 1330 (1980)
and K. G. Lynn and D. O. Welch,
Phys. Rev. B 22, 99 (1980)
] to obtain values for the positron diffusion constant D+ in single-crystal metal samples. For example, we find D+(Al)=(0.760.14) cm2 sec-1 and D+(Cu)=(1.060.20) cm2 sec-1. The former is in agreement with the deformation-potential calculation of Bergersen et al. B. Bergersen, E. Pajanne, P. Kubica, M. J. Stott, and C. H. Hodges,
[Solid State Commun. 15, 1377 (1974)]
if the positron effective mass in Al is m+=(1.590.12)me. Finally, we use our measurements to calculate the optimum thickness of transmitting positron moderators for enhancing the brightness of slow positron beams.

Mills, Allen P., Jr.; Wilson, Robert J.

1982-07-01

416

A Database of >20 keV Electron Green's Functions of Interplanetary Transport at 1 AU  

NASA Astrophysics Data System (ADS)

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.

Agueda, N.; Vainio, R.; Sanahuja, B.

2012-10-01

417

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

SciTech Connect

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.

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

418

Characterization of 1 MW, 40 keV, 1 s neutral beam for plasma heating  

SciTech Connect

Neutral beam with geometrical focusing for plasma heating in moderate-size plasma devices has been developed in Budker Institute of Nuclear Physics, Novosibirsk. When operated with hydrogen, the neutral beam power is 1 MW, pulse duration is 1 s, beam energy is 40 keV, and angular divergence is 1.2 deg. Initial ion beam is extracted and accelerated by triode multiapertures ion-optical system. To produce 1 MW neutral beam, about 40 A proton current is extracted with nominal current density of 320 mA/cm{sup 2}. Ion-optical system has 200 mm diameter grids with 44% transparency. The grids have inertia cooling and heat is removed between the pulses by water flowing in channels placed on periphery of the grids. A plasma emitter for ion extraction is produced by rf-plasma box. Ion species mix of rf plasma source amounts to 70%, 20%, and 10% of H{sup +}, H{sub 2}{sup +}, and H{sub 3}{sup +} ions, respectively, by current. Heavy impurities contribute less than 0.3%.

Sorokin, A.; Belov, V.; Davydenko, V.; Deichuli, P.; Ivanov, A.; Podyminogin, A.; Shikhovtsev, I.; Shulzhenko, G.; Stupishin, N.; Tiunov, M. [Budker Institute of Nuclear Physics, Lavrentev Ave. 11, Novosibirsk 630090 (Russian Federation)

2010-02-15

419

Characterization of 1 MW, 40 keV, 1 s neutral beam for plasma heating  

NASA Astrophysics Data System (ADS)

Neutral beam with geometrical focusing for plasma heating in moderate-size plasma devices has been developed in Budker Institute of Nuclear Physics, Novosibirsk. When operated with hydrogen, the neutral beam power is 1 MW, pulse duration is 1 s, beam energy is 40 keV, and angular divergence is 1.2. Initial ion beam is extracted and accelerated by triode multiapertures ion-optical system. To produce 1 MW neutral beam, about 40 A proton current is extracted with nominal current density of 320 mA/cm2. Ion-optical system has 200 mm diameter grids with 44% transparency. The grids have inertia cooling and heat is removed between the pulses by water flowing in channels placed on periphery of the grids. A plasma emitter for ion extraction is produced by rf-plasma box. Ion species mix of rf plasma source amounts to 70%, 20%, and 10% of H+, H2+, and H3+ ions, respectively, by current. Heavy impurities contribute less than 0.3%.

Sorokin, A.; Belov, V.; Davydenko, V.; Deichuli, P.; Ivanov, A.; Podyminogin, A.; Shikhovtsev, I.; Shulzhenko, G.; Stupishin, N.; Tiunov, M.

2010-02-01

420

Ion Sputtering from Organic Liquid Matrices Bombarded by KEV Metal Ions.  

NASA Astrophysics Data System (ADS)

Ion sputtering from organic liquid matrices bombarded by 7-66 keV metal ions has been systematically studied as a function of the properties of the primary ions (species, energy etc.) and of the chemical environment on the target's surface. Yields of deprotonated mononucleotides (dAMP or dGMP) from a glycerol matrix, doped with the surfactant hexadecylpyridinium acetate (HDPA), as a function of stopping power (dE/dX) can be explained by models, such as the cylindrical thermal spike model with Y = k(dE/dX - S_0)^2 (S _0 = threshold stopping power), that predict particle ejection essentially from the surface. Moreover, yields of deprotonated dAMP or dGMP generated by bombardment with polyatomic ions (Bi_3^{+2 }, Bi_2^+, Au _2^+, Au _3^+) exhibit a nonlinear enhancement over those generated by bombardment with monoatomic ions (Au^+, Bi^+). Nonlinear in this case means that the number of ions ejected by a given number of atoms colliding with a liquid matrix at essentially the same point in space and time, as is the case when the atoms are clustered into a single ion, is much greater than that produced by an equal number of atoms impacting individually on the same target at different positions and times. This enhancement can also be explained by, for example, the cylindrical thermal spike model.

Yen, Ten-Yang

421

D- PRODUCTION BY CHARGE TRANSFER OF 0.3-10 keV D+, D0, AND D- IN CESIUM, RUBIDIUM, AND SODIUM VAPOR TARGETS  

SciTech Connect

Equilibrium charge-state fractions for 0.3-10-keV D ions and atoms in cesium-, rubidium-, and sodium-vapor targets are reported. The D{sup -} yield from charge transfer in a thick cesium-vapor target exceeds 30 percent at energies below 800 eV. The high D{sup -} yield in cesium vapor is consistent with recent calculations of the cross sections {sigma}{sub 0-} and {sigma}{sub -0} at low energies; at energies above 2.5 keV, the D{sup -} yield is consistent with our measurements of {sigma}{sub 0-} and {sigma}{sub -0}. The D{sup -} yield from charge transfer in rubidium vapor is similar to that for cesium vapor. For sodium vapor, however, there is a broad maximum of about 10 percent D{sup -} yield at about 3 keV, with slight structure at lower energies, implying structure in one of the charge-transfer cross sections.

Schlachter, A.S.; Stalder, K.R.; Stearns, J.W.

1980-04-01

422

Operating experience with a 100-keV, 100-mA H/sup -/ injector  

SciTech Connect

According to beam dynamics calculations it should be possible to accelerate a high-perveance beam in a radio-frequency quadrupole (RFQ) accelerator with low emittance growth and nearly 100% capture efficiency. A 100-mA, 100-keV H/sup -/ ion injector with a 5-Hz, 1-ms duty factor was built for use with this accelerator, but the beam emittance at 100 keV was found to be two to four times the value previously determined at 20 keV. This emittance growth was traced to the 20-keV beam transport, where an instability occurred in the background plasma created by beam ionization of the residual gas. The injector has been rebuilt with a shorter transport length, resulting in greatly reduced emittance growth.

Allison, P.W.; Sherman, J.D.

1983-01-01

423

Radiation damage distributions for 300 keV antimony ions implanted into silicon  

NASA Astrophysics Data System (ADS)

Two well-known theories of Brice and of Winterbon and one simplified theory of radiation damage distributions are statistically compared with RBS data for room temperature 300 keV antimony ion implantation of silicon.

Tatarkiewicz, Jakub; Krynicki, Janusz; Grtzschel, Rainer; Paprocki, Krzysztof

1985-01-01

424

SPECT imaging (140-364 keV): Influence of photon scattering and penetration on backprojected noise within tomographic plane  

SciTech Connect

In functional imaging with SPECT, differential uptake measurements within the tomographic plane are important. In many investigations, a distributed source or multiple sources within this plane are imaged. Backprojected noise may be significant, influencing differential uptake. Noise factors, apart from backprojection algorithms include photon scattering and collimator photon penetration. The influence of noise on differential uptake within the transverse plane was empirically evaluated for Tc-99m (140 keV), Ga-67, 993,184 keV) and I-131 (364 keV). A Picker International SPECT system, equipped with LEC and thick septa MEC and Iodine collimators (theoretical leakage for both<3%), was employed, to minimize photon penetration. A dual concentric ring (contrast) phantom was scanned and results of higher photon emitters compared to Tc-99m data. The activity in the outer/inner ring was 3:1, to critically evaluate noise within the transverse plane. Acquired counts were large (>20 x 10/sup 6/) to minimize statistical (unstructed) noise. For given acquisition and filter parameters, the noise level for Ga-67 was approximately three times greater than the Tc-99m, the latter attributed to scatter contribution to the lower energy window. This noise was non-uniform and degraded differential uptake measurements. The noise level for I-131 was approximately twice that for Tc-99m and was more uniform than Ga-67. The noise was attributed, in part, to photon penetration. Despite difference in collimation, data suggest that provided collimator sensitivity can be reduced, the limiting noise factor is photon scattering where multiple peaks are involved.

Saw, C.B.; Clarke, L.P.; Hourani, M.; Leong, L.; Gentili, A.; Sfakianakis, G.; Serafini, A.

1984-01-01

425

10100 keV electron acceleration and emission from solar flares  

Microsoft Academic Search

We present an analysis of spacecraft observations of non-thermal X-rays and escaping electrons for 5 selected small solar flares in 1967. OSO-3 multi-channel energetic X-ray measurements during the non-thermal component of the solar flare X-ray bursts are used to derive the parent electron spectrum and emission measure. IMP-4 and Explorer-35 observations of > 22 keV and > 45 keV electrons

R. P. Lin; H. S. Hudson

1971-01-01

426

The Search for 17KEV Neutrino Emission in the Beta-Decay Spectrum of SULFUR35  

Microsoft Academic Search

For this work, the electron momentum spectrum resulting from the beta-decay of ^{35}S, ^{35}{rm S} to ^ {35}{rm Cl} + {rm e }^- + |nu_{rm e}quad (E_0 - m_{e} = 167 {rm keV, T}_{1\\/2 } = 87.4 {rm days}), has been measured in order to search for the presence of 17-keV electron neutrino emission. Originally observed by J. Simpson in

Gregg Evan Berman

1994-01-01

427

17-keV neutrino in a left-right model  

SciTech Connect

We examine the possibility of embedding a 17-keV neutrino in a left-right model with three generations of left- and right-handed neutrinos. In particular, we study scenarios where the 17-keV neutrino is a pseudo Dirac neutrino and its mass is generated radiatively. Two heavy right-handed neutrinos have their mass scale set by the SU(2)[sub [ital R

Whisnant, K.; Woodside, J.; Young, B. (Physics Department and Ames Laboratory, Iowa State University, Ames, Iowa 50011 (United States))

1993-01-01

428

Measurements of keV neutron capture cross sections with a 4. pi. barium fluoride detector: Examples of sup 93 Nb, sup 103 Rh, and sup 181 Ta  

SciTech Connect

A new experimental method has been implemented for precise measurements of neutron capture cross sections in the energy range from 3 to 200 keV. Neutrons are produced via the {sup 7}Li({ital p},{ital n}){sup 7}Be reaction using a pulsed 3-MV Van de Graaff accelerator. The neutron energy is determined by the time-of-flight (TOF) technique using flight paths of less than 1 m. Capture events are detected with a 4{pi} barium fluoride detector. This detector is characterized by a resolution in gamma-ray energy of 14% at 662 keV and 7% at 2.5 MeV, a time resolution of 500 ps, and a peak efficiency of 90% at 1 MeV. Capture events are registered with {similar to}95% probability above a gamma-ray threshold of 2.5 MeV. The combined effect of the relatively short primary flight path, the 10-cm inner radius of the detector sphere, and of the low capture cross section of BaF{sub 2} shifts the background due to capture of sample scattered neutrons in the scintillator to later TOF and therefore leaves the high-energy portion of the TOF spectrum undisturbed. The high efficiency and good energy resolution for capture gamma-rays yields a further reduction of this background by using only the relevant energy channels for data evaluation. In the first measurements with the new detector, the neutron capture cross sections of {sup 93}Nb, {sup 103}Rh, and {sup 181}Ta were determined in the energy range from 3 to 200 keV relative to gold as a standard. The cross-section ratios could be determined with overall systematic uncertainties of 0.7 to 0.8%; statistical uncertainties were less than 1% in the energy range from 20 to 100 keV, if the data are combined in 20-keV wide bins. This represents an improvement of factors 5--10 compared to existing experimental methods. The necessary sample masses were of the order of one gram.

Wisshak, K.; Voss, F.; Kaeppeler, F. (Kernforschungszentrum Karlsruhe, Institut fuer Kernphysik, D-7500 Karlsruhe (Federal Republic of Germany)); Reffo, G. (Comitato Nazionale dell'Energia Nucleare e dell'Energie Alternative, I-40138 Bologna (Italy))

1990-10-01

429

Development of an 18 keV X-Ray Thomson Scattering Source for the Characterization of Dense States of Matter  

NASA Astrophysics Data System (ADS)

The accurate characterization of material properties under extreme conditions is an important issue for the understanding of high energy density states of matter, from planetary interiors to capsule implosions relevant to inertial confinement fusion. High energy x-ray Thomson Scattering at 18 keV will make it possible to characterize very dense states of matter such as 50x compressed beryllium, ICF-like ablator materials, aluminum compressed up to 4x by a single shock, and isochorically heated mid-Z elements (such as Ti). Here we present results from a backscattering experiment carried out at the Omega Laser Facility, performed on aluminum, the highest-Z material probed to this date. We will also demonstrate the viability of molybdenum He-alpha (18 keV) as a suitable backlighter probe source.

Ma, Tammy; Lee, Haeja; Doeppner, Tilo; Falcone, Roger; Fortmann, Carsten; Kritcher, Andrea; Landen, Otto; Glenzer, Siegfried

2010-11-01

430

Scattering of 7.3 keV conversion electrons from a 57Co source covered gradually by gold absorbers of various thicknesses  

NASA Astrophysics Data System (ADS)

The conversion electrons emitted with initial energy of 7.3 keV from the K-shell of 57Fe atoms were measured with an electrostatic spectrometer set to the instrumental resolution of 7 eV. The source /- 57Co on an Al backing /- was covered in successive steps by six evaporated Au layers and changes of the line shapes were recorded. The thicknesses of the Au absorbers determined by neutron activation analysis varied from 2.7 to 21 nm, i.e. up to about three times the inelastic mean free path of the 7.3 keV electrons. The individual elastic and inelastic scattering events in the Al backing, Au absorbers and carbonaceous contamination overlayer were simulated by the Monte Carlo method. When the Au energy loss function derived by Yoshikawa et al. was applied in MC simulations, a reasonable agreement with measured line shapes was reached even for the thickest Au absorbers.

Dragoun, O.; palek, A.; Kovalk, A.; Yakushev, E. A.; Ryav, M.; Frna, J.; Brabec, V.; Novgorodov, A. F.; Liljequist, D.

2002-08-01

431

State-resolved study of keV sputtered neutral atoms by resonance ionization spectroscopy  

SciTech Connect

We have performed simultaneous measurements of energy-, and angle-resolved distributions of Ni atoms desorbed from a single crystal Ni{l_brace}100{r_brace} surface bombarded by 5 keV Ar{sup +} ions. Ground state and six low-lying excited states from the {ital a}{sup 3}{ital F}{sub {ital J}} ({ital J}=4,3,2) and {ital a}{sup 3}{ital D}{sub {ital J}} ({ital J}=3,2,1) manifolds as well as {ital a}{sup 1}{ital D}{sub 2} have been investigated along different azimuths. Both {ital a}{sup 3}{ital F}{sub {ital J}} and {ital a}{sup 1}{ital D}{sub 2} states have closed shell electronic structure, 3{ital d}{sup 8}4{ital s}{sup 2}, while the {ital a}{sup 3}{ital D}{sub {ital J}} states are open shell electronic states, 3{ital d}{sup 9}4{ital s}{sup 1}. Angle-integrated energy distributions demonstrate a strong dependence on the electronic structure while the magnitude of the excitation energy does not significantly alter the results. This is the first conclusive evidence that electronic structure rather than excitation energy is the primary factor in determining kinetic energy distributions of sputtered neutral species. Population distribution among the seven electronic states are obtained through two sets of measurements performed on two experimental apparati: one measures the energy- and angle-integrated resonance ionization signal intensities of the sputtered Ni; the other measures the resonance ionization signal intensities of thermally evaporated Ni atoms with a known heating temperature. The experiment results show that the population distribution is very different from Boltzman-type distribution with {ital a}{sup 3}{ital D}{sub 3} and {ital a}{sup 3}{ital D}{sub 2} states more intensely populated. The work also illustrates the power of RIS to perform quantum state specific measurements on fast moving atoms. {copyright} 1995 {ital American} {ital Institute} {ital of} {ital Physics}

He, C.; Postawa, Z.; Rosencrance, S.; Chatterjee, R.; Garrison, B.J.; Winograd, N. [Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

1995-04-01

432

Electron collisional detachment processes for a 250 keV D/sup -/ ion beam in a partially ionized hydrogen target  

SciTech Connect

Neutral atom beams with energies above 200 keV may be required for various purposes in magnetic fusion devices following TFTR, JET and MFTF-B. These beams can be produced much more efficiently by electron detachment from negative ion beams than by electron capture by positive ions. We have investigated the efficiency with which such neutral atoms can be produced by electron detachment in partially ionized hydrogen plasma neutralizers.

Savas, S.E.

1980-09-01

433

Electron elastic scattering cross sections from 1 keV to 100 MeV for elements Z = 1 to 100  

SciTech Connect

Tables of electron elastic scattering differential cross sections of elements (Z = 1 to 100) are given for electron energies in the range of 1 keV to 100 MeV and scattering angles in the range of 1 to 179$sup 0$. The function describing the asymmetry of a polarized electron beam after the scattering process is also included in the tables. (auth)

Storm, E.; Hancock, J.H.

1975-04-01

434

Measuring the absolute sensitivity of an X-ray electron-optical image converter in the range 7-20 keV  

Microsoft Academic Search

The absolute sensitivity of an X-ray electron-optical image converter with a MCP used as both photocathode and amplifier has been investigated using synchrotron radiation from the VEPP-3 storage ring (INP, Novosibirsk) in the energy range of 7 to 20 keV. In this spectral range the response of the converter increases from 1200 to 2200 blue photons at the output per

I. P. Dolbnya; B. A. Knyazev; V. P. Simonov; G. G. Feldman

1991-01-01

435

950 keV, 3.95 MeV and 6 MeV X-band linacs for nondestructive evaluation and medicine  

Microsoft Academic Search

We are developing compact X-band linac X-ray sources for nondestructive evaluation and medicine. First, we develop a portable X-ray system by a 950keV 9.4GHz X-band linac to realize on-site inspection. We use a low power (250kW) magnetron as an RF source for compactness of the whole system. Since the RF power source is quite small and the stored energy in

Mitsuru Uesaka; Takuya Natsui; Kiwoo Lee; Katsuhiro Dobashi; Tomohiko Yamamoto; Takeshi Fujiwara; Haito Zhu; Kazuyuki Demachi; Eiji Tanabe; Masashi Yamamoto; Naoki Nakamura; Joichi Kusano; Toshiyasu Higo; Shigeki Fukuda; Mitsuhiro Yoshida; Shuji Matsumoto

2011-01-01

436

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

Microsoft Academic Search

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

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

2008-01-01

437

A Medium Survey of the Hard X-Ray Sky with the ASCA Gas Imaging Spectrometer: The (2--10 keV) Number Counts Relationship  

Microsoft Academic Search

In this paper, we report the first results of a medium survey program conducted in the 2-10 keV energy band using data from the GIS2 instrument onboard the ASCA satellite. We have selected from the ASCA public archive (as of 1996 February 14) 87 images suitable for this project. Sixty serendipitous X-ray sources with a signal-to-noise ratio greater than 3.5

I. Cagnoni; R. della Ceca; T. Maccacaro

1998-01-01

438

Sterilization of foods with low-energy electrons (soft-electrons)  

Microsoft Academic Search

Electrons with an energy of 300 keV or lower were defined as Soft-electrons, which showed several advantages over conventional irradiation with gamma-rays or high-energy electrons in decontamination of grains and spices. Energies of electrons necessary to reduce microbial loads to levels lower than 10 CFU\\/g were 60 keV for brown rice, 75 keV for wheat, 100 keV for white pepper,

Toru Hayashi; Yoko Takahashi; Setsuko Todoriki

1998-01-01

439

The INTEGRAL View Of The 511 keV Annihilation Line In Our Galaxy  

NASA Astrophysics Data System (ADS)

It is well know from theory and laboratory practice that an electron-positron pair can annihilate into a couple of 511 keV (the electron rest mass) gamma ray photons. The first detection of 511 keV photons from the Galactic center region dates back to early seventies. Soon after, a continuum gamma ray emission due to 3 gamma ortho-positronium decay was also measured. A 511 keV line in the Galactic gamma ray emission gives a unique proof that a large number of positrons are injected in the astrophysical environments, but nowadays we still do not know where these particles are generated. Positrons can be generated by a number of processes, in particular beta+ decays of unstable isotopes produced by stars and supernovae and energetic outflows from compact objects, but the few claimed detections of a 511 keV line from compact galactic sources are quite controversial. This fact could be explained by propagation of positrons in the intergalactic medium before they annihilate away from the birth place. The measure made with the spectrometer SPI aboard INTernational Gamma RAy Laboratory (INTEGRAL), launched on October 17 2002, confirms that about 10E43 positrons per second annihilate in the bulge of our Galaxy. Moreover, there is some evidence of an asymmetry of the 511 keV emission along the Galactic longitude, possibly correlated with the spacial distribution of the hard X (E > 20 keV) Low Mass X-ray Binaries detected by the imager IBIS aboard INTEGRAL. With IBIS, using about 5 years of observations, we find no evidence of 511 keV point sources. With an exposure of 10 Ms, in the center of the Galaxy we estimate a 1.6 x 10E-04 ph/cm2/s flux 2 sigma upper limit; a similar limit is given in a wide area in the Galactic center region with similar exposures.

De Cesare, G.

2011-09-01

440

Millimeter-order imaging technique from 100 keV to MeV based on germanium Compton camera  

NASA Astrophysics Data System (ADS)

A prototype molecular imaging system that features wide-band imaging capability from 100 keV to MeV was developed based on a germanium Compton camera. In this system, radiotracer imaging is performed through the Compton imaging technique above 300 keV and through the coded mask imaging technique below 200 keV. For practical use, small animal imaging requires spatial resolution of the order of millimeters. We conducted tests with a multiple-well phantom containing 99mTc (140 keV) and 54Mn (834 keV), and confirmed the spatial resolution of better than 3.2 mm for the phantom placed 35 mm above the detector. We also report imaging results of a living mouse into which we injected 99mTc (140 keV) and 54Mn (834 keV).

Takeda, Shin'ichiro; Fukuchi, Tomonori; Kanayama, Yousuke; Motomura, Shinji; Hiromura, Makoto; Takahashi, Tadayuki; Enomoto, Shuichi

2010-08-01

441

2-gamma decay of the 662-keV isomer in ^137Ba  

NASA Astrophysics Data System (ADS)

2-gamma decay of the 662-keV ^137Ba isomer following ^137Cs beta decay has been observed using two 3"x3" NaI detectors, a 20.5-?Ci source, and a Pb shielding geometry designed to minimize direct and sequential Compton scattering backgrounds. In runs totaling 144 days, a 662-keV peak has been observed in the profile across the diagonal connecting 662-keV axis points in a 2-dimensional coincidence pulse-height spectrum. A preliminary value of 2.0(6)x10-6 is derived for the 2-gamma/1-gamma intensity ratio. The distribution of 662-keV events along the 2D diagonal is a continuum centered at 331-331 keV with a shape favoring a double quadrupole E2-M2 or M2-E2 decay sequence. Our result compares with upper limits of < 10-5, our assessment of the Beusch experiment [1], and < 2.2x10-6 by Basenko et al. [2]. It will be compared with theoretical estimates. [4pt] [1] W. Beusch, Helv Phys. Acta 33, 363 (1960)[0pt] [2] V.K. Basenko, A.N. Berlizov, and G.A. Prokopets, Bull. Russ. Acad. Sci. 56, 94 (1992)

Millener, D. J.; Sutter, R. J.; Alburger, D. E.

2011-10-01

442

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

SciTech Connect

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

AJ Peurrung; RJ Arthur; BD Geelhood; RD Scheele; RJ Elovich; SL Pratt

2000-03-22

443

Suprathermal (E greater than 5 keV) ENA images of the Heliosphere from Cassini and in situ Voyager measurements: Is there pressure balance?  

NASA Astrophysics Data System (ADS)

The Ion and Neutral Camera (INCA), part of the Magnetospheric Imaging Instrument(MIMI) sensor suite on the Cassini orbiter at Saturn, is an ENA imager designed to obtain measurements of magnetospheric phenomena, and has done so for more than five years. When not pointing at the planet, INCA can sense ENA from other sources, notably those traversing the interplanetary medium from all directions. Maps of such emissions (Krimigis et al, 2009) have now been constructed spanning the energy range 5 < E < 55 keV, and show a "Belt" in the sky of about 100 FWHM. Similarly, maps < 6 keV have been obtained by the IBEX mission (McComas et al, 2009) and show a "Ribbon" that is narrower than the Belt and inclined to it in both ecliptic latitude (25 ) and longitude (30 ). Measurements of energetic ions by Voyagers 1, 2 in the heliosheath (Decker et al, 2009) show pressures 28 keV about 0.2 pdynes/cm2 vs 0.04 pdynes/cm2 for the local B about 0.1nT (Burlaga et al, 2009), i.e. ? > 5. The overlap in energy between Voyager ions and Cassini ENA intensities (averaged over the ENA line of sight) enables us to deduce ion fluxes in the heliosheath, thus providing a continuous spectrum 5 < E < 4000 keV. These measurements are then used to estimate the thickness of the heliosheath (about 50 AU) and the local pressure ( 1.3 pdynes/cm2 ), suggesting ? > 33. The pressure at < 6 keV is more difficult to estimate because appropriate Voyager normalization between the IBEX ENA and in situ heliosheath ions is currently unavailable. Nevertheless, pick up ions (PUI) dominate the heliosheath at > 5 keV, at least at the location of the two Voyagers. Based on the symmetrical distribution of ENA intensities in galactic coordinates, it is hypothesized that the local interstellar magnetic field plays an important role in determining the shape of the heliospheric cavity and it must have a central role in global pressure balance of heliosheath plasma and the local interstellar flow. >>

Krimigis, Stamatios; Krimigis, Stamatios M.; Mitchell, Donald; Roelof, Edmond; Decker, Robert

444

A method to obtain a Maxwell-Boltzmann neutron spectrum at kT=30 keV for nuclear astrophysics studies  

NASA Astrophysics Data System (ADS)

A method based on shaping the proton beam energy in order to shape the neutron beam energy to a desired form for accelerator-based neutron sources is proposed. An application to a superconductive RFQ proton accelerator of 5 MeV and 50 mA for the production of a stellar neutron spectrum at thermal energy equal to 30 keV using the 7Li(p,n)7Be reaction is investigated. The chosen energy beam shaper is a carbon foil which shapes the quasi-monochromatic proton beam to a quasi-Gaussian distribution: after the carbon foil, the beam is still shaped by chopping the Gaussian distribution at the reaction energy threshold. The obtained proton beam is impinged in a metallic lithium target. The concepts of the energy shaper, the proposed lithium target and the calculations performed to remove their power load are presented. Calculations show that a power density of 3 kW/cm2 can be sustained by the target which produces a forward-directed neutron source of 7.31010 neutrons/s. The obtained neutron spectrum resembles a Maxwell-Boltzmann distribution at kT=30 keV with a coefficient of determination of 0.997. The method is intended to be applied in activation analysis for measuring the Maxwellian-averaged neutron capture cross-section of elements of interest for astrophysics and validation of integral neutron data in the epithermal energy range.

Mastinu, P. F.; Martn Hernndez, G.; Praena, J.

2009-04-01

445

Measurement of the 183 keV Resonance in 17O(p,alpha)14N using a Novel Technique  

SciTech Connect

We have developed a novel technique for measurements of low energy (p,alpha) reactions using heavy ion beams and a differentially-pumped windowless gas target. We applied this new approach to study the 183 keV resonance in the 17O(p,alpha)14}N reaction. We report a resonance energy (center-of-mass) of 183.5{+0.1}{-0.4} keV, a resonance strength of 1.70 +/- 0.15 meV, and set an upper limit (95\\% confidence) on the total width of the state of < 0.1 keV. This resonance is important for the 17O(p,alpha)14}N reaction rate, and we find that 18F production is significantly decreased in low mass ONeMg novae but less affected in more energetic novae. We also report the first determination of the stopping power for oxygen ions in hydrogen gas near the peak of the Bragg curve (E=193 keV/u) to be (63+/-1)e-15 eV-cm2.

Moazen, Brian H [ORNL; Bardayan, Daniel W [ORNL; Blackmon, Jeff C [ORNL; Chae, Kyung Yuk [ORNL; Chipps, Kelly A [ORNL; Domizioli, Carlo P [ORNL; Fitzgerald, Ryan [ORNL; Greife, Uwe [ORNL; Hix, William Raphael [ORNL; Grzywacz-Jones, Kate L [ORNL; KOZUB, RAYMOND L [ORNL; Lingerfelt, Eric J [ORNL; Livesay, Jake [ORNL; Nesaraja, Caroline D [ORNL; Pain, Steven D [ORNL; Roberts, Luke F [ORNL; Shriner, Jr., John F [ORNL; Smith, Michael Scott [ORNL; Thomas, Jeffrey S [ORNL

2007-01-01